membrane filtration and polymer coagulation for …
TRANSCRIPT
The Pennsylvania State University
The Graduate School
College of Engineering
MEMBRANE FILTRATION AND POLYMER COAGULATION FOR WATER
REUSE IN LAUNDRY WASTEWATER TREATMENT FROM BENCH-SCALE
TO FULL-SCALE OPERATION
A Thesis in
Environmental Engineering
by
Xia Shang
copy 2012 Xia Shang
Submitted in Fulfillment
of the Requirements
for the Degree of
Master of Science
May 2012
II
The thesis of Xia Shang was reviewed and approved by the following
Brian A Dempsey
Professor of Environmental Engineering
Thesis Adviser
Rachel A Brennan
Associate Professor of Environmental Engineering
Fred S Cannon
Professor of Environmental Engineering
Peggy A Johnson
Professor of Civil Engineering
Head of the Department of Civil and Environmental Engineering
Signatures are on file in the Graduate School
III
ABSTRACT
Membrane filtration has been widely employed for treating potable water and wastewater
This thesis dealt with the use of microfiltration (MF) for treatment and reuse of laundry
wastewater The most important issues with respect to laundry water reuse are treated
water quality membrane fouling and cost and energy consumption Only the first two of
these issues were addressed in this thesis This thesis was focused on developing
methods to improve performance of the Armyrsquos full-scale Shower Water Reuse System
(SWRS) specifically for treating and reusing laundry wastewater The SWRS uses
pretreatment with pre- filtration (15 microm steel mesh) MF (02 microm PVDF) reverse osmosis
(RO) and Granular activated carbon (GAC) Based on the information from the Army
and their contractors the major problem in using the SWRS for laundry wastewater was
fouling of the MF Therefore the objectives were to investigate the effects of coagulants
for improving MF performance and for removal of contaminants
Coagulation has been used prior to MF for decreasing membrane fouling enhancing
MF flux and improving removal of contaminants There are problems in employing
conventional coagulants (eg alum and ferric chloride) for treating laundry wastewater due
to the difficulties in achieving effective coagulation at high pH high total suspended solids
(TSS) and high chemical oxygen demand (COD) In particular the very high doses of
inorganic coagulants that are required for these water quality conditions result in voluminous
sludge production which is inappropriate prior to membrane treatment As a result cationic
polyelectrolytes were investigated
The effects of different cationic polymers on laundry wastewater treatment were first
investigated using batch coagulationprecipitation with sedimentation (without membrane
filtration) evaluating Zeta Potential (ZP) changes and removal of COD TSS turbidity and
total phosphorus (TP) Subsequently the influence of cationic polymers on MF performance
was studied by measuring specific resistance and cake compressibility Based on these initial
experiments a commercial poly-quaternary amine containing epichlorohydrin
dimethylamine (Epi-DMA) was selected as the best polymer based on successful
neutralization of contaminant charge and low specific resistance on polyvinylidine
fluoride (PVDF) MF over a broad range of pH and coagulant dose The initial
experiments also demonstrated that Epi-DMA was effective for removal of contaminants
IV
after sedimentation eg 63 of COD 77 of TSS 96 of turbidity and 26 of TP
were removed
Subsequent bench-scale experiments focused on evaluating the effects of Epi-DMA
on reducing membrane fouling and increasing critical flux defined as the maximum flux
for which trans-membrane pressure (TMP) increased linearly with permeate flux Epi-
DMA coagulation significantly increased the critical flux from 50 L m-2h-1 for the raw
sample to 510 L m-2h-1 for the charge neutralization (CN) condition Epi-DMA additions
also substantially decreased resistance to filtration over a broad range of coagulant doses
including doses less than 50 of that required for CN
The effects of Epi-DMA on MF of laundry wastewater were further investigated by
conducting multi-cycle tests with backwashing every 15 min These bench-scale
experiments were run at 50 L m-2h-1 which is a typical membrane flux used in full-scale
MF operations The multi-cycle experiments demonstrated that increases in the trans-
membrane pressure (TMP) that occurred during each cycle were nearly eliminated by the
backwash for under-dosing (UD) and CN conditions but that TMP increases during over-
dosing (OD) coagulation conditions were not eliminated during backwash
Finally the use of Epi-DMA was tested on the full-scale SWRS which was set up
outside the Penn State laundry facility The setup included two 3000 gal bladders
Laundry wastewater was pumped from the laundry facility into the bladders and Epi-
DMA was introduced into the bladders prior to the pre-treatment The effects on the
down-stream membrane units were investigated The tests were performed over a range
of Epi-DMA doses including no coagulant UD CN and OD The tests demonstrated
that negligible fouling of the MF occurred but serious fouling was observed in the RO
unit Formation of inorganic precipitates was suspected as the main reason for RO failure
The full-scale MF without coagulant did not foul as much as the bench-scale MF
experiments had indicated This could have been due to more rigorous backwashing with
the SWRS or due to retention of partially coagulated solids in the bladders despite inter-
experiment flushing with tap water Issues regarding MF and RO behavior in the full-
scale SWRS are currently under investigation and some conclusions are reported in this
thesis
V
TABLE OF CONTENTS
LIST OF FIGURES X
LIST OF TABLES XIV
ACKNOWLEDGEMENTS XVI
DEDICATION XVII
ABBREVIATIONS XVIII
CHAPTER 1 INTRODUCTION 1
11 Project background 1
12 Objectives 4
13 Organization of the thesis 5
CHAPTER 2 MATERIALS AND METHODS 7
21 Laundry wastewater description 7
22 Zeta potential (COD TSS Turbidity TP) 8
221 Zeta Sizer Nano series 8
222 Zeta Compact 9
22 DI water 9
23 pH and conductivity 9
24 Total suspended solids 9
25 COD and Total phosphorus 9
26 Turbidity 10
27 SEM 10
28 TEM 10
29 Particle size distribution and particle images 10
210 Polymeric coagulants 11
VI
211 Membranes 13
2111 Membrane characteristics 13
2112 Preparation of membrane 13
2113 Hydraulic cleaning of membranes 14
2114 Flux recovery 14
212 Batch tests for zeta potential titration 14
213 Jar tests 15
214 Specific resistance and cake compressibility 15
215 Critical flux determination 18
2151 Sample pretreatment 18
2152 Microfiltration process 19
216 Multi-cycle filtration test 20
2161 Sample preparation 20
2162 Microfiltration process 20
217 Dead end microfiltration test 22
CHAPTER 3 IMPACT OF POLYMERS ON COAGULATION OF LAUNDRY
WASTEWATER 23
31 Batch tests 24
32 Jar tests 26
33 Specific resistance to filtration and cake compressibility 29
34 Summary 33
CHAPTER 4 IN-LINE COAGULATION AND MF CRITICAL FLUX AND
LONG-TERM MF OPERATION 34
41 Jar tests identifying dosing regimes 35
42 Critical Fluxes for the dosing regimes 36
43 Multi-cycle constant flux MF experiments 39
VII
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation 44
45 Contaminant removals in bench scale MF experiments 46
45 Summary 47
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE SHOWER WASTEWATER
REUSE SYSTEM 48
51 SWRS description 50
511 System overview 50
512 Microfiltration characteristics 53
513 RO filter 53
514 Chemical injection system 53
515 Air system 54
516 GAC filter and UV light 54
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy 54
52 SWRS setup and dosing strategy at Penn State Laundry Building 54
53 SWRS operation at various microfiltration permeate flux with clean
water 56
54 Results of long-term SWRS operation 57
55 Water quality changes 60
56 SWRS operation problems 61
561 Pre-filter fouling 61
562 RO scaling 61
563 Other problems 62
57 Hypotheses regarding differences between bench-scale experiments and
full-scale tests 62
VIII
571 Water quality 62
572 Pre-filter sequence 62
573 Cross-flow and backwash 62
574 Coagulated lint particle in the settlement 63
58 Additional multi-cycle bench-scale microfiltration tests on Penn State
laundry wastewater 63
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis 65
591 RO fouling during operation 65
592 RO membrane autopsy and sample preparation 65
593 SEM images 65
594 EDS analysis 66
595 TEM images 72
596 RO cleaning and cleaning solutions 74
597 Cleaning solution analysis 75
510 Summary 76
CHAPTER 6 CONCLUSIONS 77
61 Polymer selection for laundry wastewater treatment 77
62 Bench scale MF experiments 77
63 Full-scale tests and RO scaling 79
CHAPTER 7 RECOMMENDATIONS 80
REFERENCES 81
Appendix A Material and Water Quality changes in Bench Scale Experiments 86
Appendix B Example of Data Processing for Critical Flux Determination Experiment
100
Appendix C Example of Data Processing for a Multi-cycle Membrane Filtration
Experiment 104
IX
Appendix D Images of SWRS Components and Hose Connection 110
Appendix E Water Quality During SWRS Operation 112
Appendix F SWRS Backwash Strategy without Starting the High Pressure Pump 116
Appendix G RO Fouling Report 117
X
LIST OF FIGURES
Figure 21 Schematic diagram of critical flux determination setup 20
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane
filtration test (By Dr Hyunchul Kim) 21
Figure 23 Schematic diagram of dead-end microfiltration experimental setup 22
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH
108 25
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different
pH conditions (pH 72 on the left side) and (pH 11 on the right side)
using five polymers 28
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope)
during the membrane (022 microm PVDF) filtration of raw and coagulated
lint wastewaters (22ordmC) Two different coagulation regimes for each
polymer were employed ie charge-neutralizing (ZP between plusmn5 mV
and highest turbidity removal) and underdosing (more negative ZP
value and relatively poorer contaminant removal) conditions 32
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using
NALCOLYTE 8105 as the coagulant at pH 11 35
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux
determination after various pre-treatment by coagulation with
NALCOLYTE 8105 at pH 11 and constant temperature of 40 ˚C
Permeate flux was constant for 10 min and increased stepwise 38
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for charge
neutralization condition at pH 11 and constant temperature of 40 ˚C 40
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30
II
The thesis of Xia Shang was reviewed and approved by the following
Brian A Dempsey
Professor of Environmental Engineering
Thesis Adviser
Rachel A Brennan
Associate Professor of Environmental Engineering
Fred S Cannon
Professor of Environmental Engineering
Peggy A Johnson
Professor of Civil Engineering
Head of the Department of Civil and Environmental Engineering
Signatures are on file in the Graduate School
III
ABSTRACT
Membrane filtration has been widely employed for treating potable water and wastewater
This thesis dealt with the use of microfiltration (MF) for treatment and reuse of laundry
wastewater The most important issues with respect to laundry water reuse are treated
water quality membrane fouling and cost and energy consumption Only the first two of
these issues were addressed in this thesis This thesis was focused on developing
methods to improve performance of the Armyrsquos full-scale Shower Water Reuse System
(SWRS) specifically for treating and reusing laundry wastewater The SWRS uses
pretreatment with pre- filtration (15 microm steel mesh) MF (02 microm PVDF) reverse osmosis
(RO) and Granular activated carbon (GAC) Based on the information from the Army
and their contractors the major problem in using the SWRS for laundry wastewater was
fouling of the MF Therefore the objectives were to investigate the effects of coagulants
for improving MF performance and for removal of contaminants
Coagulation has been used prior to MF for decreasing membrane fouling enhancing
MF flux and improving removal of contaminants There are problems in employing
conventional coagulants (eg alum and ferric chloride) for treating laundry wastewater due
to the difficulties in achieving effective coagulation at high pH high total suspended solids
(TSS) and high chemical oxygen demand (COD) In particular the very high doses of
inorganic coagulants that are required for these water quality conditions result in voluminous
sludge production which is inappropriate prior to membrane treatment As a result cationic
polyelectrolytes were investigated
The effects of different cationic polymers on laundry wastewater treatment were first
investigated using batch coagulationprecipitation with sedimentation (without membrane
filtration) evaluating Zeta Potential (ZP) changes and removal of COD TSS turbidity and
total phosphorus (TP) Subsequently the influence of cationic polymers on MF performance
was studied by measuring specific resistance and cake compressibility Based on these initial
experiments a commercial poly-quaternary amine containing epichlorohydrin
dimethylamine (Epi-DMA) was selected as the best polymer based on successful
neutralization of contaminant charge and low specific resistance on polyvinylidine
fluoride (PVDF) MF over a broad range of pH and coagulant dose The initial
experiments also demonstrated that Epi-DMA was effective for removal of contaminants
IV
after sedimentation eg 63 of COD 77 of TSS 96 of turbidity and 26 of TP
were removed
Subsequent bench-scale experiments focused on evaluating the effects of Epi-DMA
on reducing membrane fouling and increasing critical flux defined as the maximum flux
for which trans-membrane pressure (TMP) increased linearly with permeate flux Epi-
DMA coagulation significantly increased the critical flux from 50 L m-2h-1 for the raw
sample to 510 L m-2h-1 for the charge neutralization (CN) condition Epi-DMA additions
also substantially decreased resistance to filtration over a broad range of coagulant doses
including doses less than 50 of that required for CN
The effects of Epi-DMA on MF of laundry wastewater were further investigated by
conducting multi-cycle tests with backwashing every 15 min These bench-scale
experiments were run at 50 L m-2h-1 which is a typical membrane flux used in full-scale
MF operations The multi-cycle experiments demonstrated that increases in the trans-
membrane pressure (TMP) that occurred during each cycle were nearly eliminated by the
backwash for under-dosing (UD) and CN conditions but that TMP increases during over-
dosing (OD) coagulation conditions were not eliminated during backwash
Finally the use of Epi-DMA was tested on the full-scale SWRS which was set up
outside the Penn State laundry facility The setup included two 3000 gal bladders
Laundry wastewater was pumped from the laundry facility into the bladders and Epi-
DMA was introduced into the bladders prior to the pre-treatment The effects on the
down-stream membrane units were investigated The tests were performed over a range
of Epi-DMA doses including no coagulant UD CN and OD The tests demonstrated
that negligible fouling of the MF occurred but serious fouling was observed in the RO
unit Formation of inorganic precipitates was suspected as the main reason for RO failure
The full-scale MF without coagulant did not foul as much as the bench-scale MF
experiments had indicated This could have been due to more rigorous backwashing with
the SWRS or due to retention of partially coagulated solids in the bladders despite inter-
experiment flushing with tap water Issues regarding MF and RO behavior in the full-
scale SWRS are currently under investigation and some conclusions are reported in this
thesis
V
TABLE OF CONTENTS
LIST OF FIGURES X
LIST OF TABLES XIV
ACKNOWLEDGEMENTS XVI
DEDICATION XVII
ABBREVIATIONS XVIII
CHAPTER 1 INTRODUCTION 1
11 Project background 1
12 Objectives 4
13 Organization of the thesis 5
CHAPTER 2 MATERIALS AND METHODS 7
21 Laundry wastewater description 7
22 Zeta potential (COD TSS Turbidity TP) 8
221 Zeta Sizer Nano series 8
222 Zeta Compact 9
22 DI water 9
23 pH and conductivity 9
24 Total suspended solids 9
25 COD and Total phosphorus 9
26 Turbidity 10
27 SEM 10
28 TEM 10
29 Particle size distribution and particle images 10
210 Polymeric coagulants 11
VI
211 Membranes 13
2111 Membrane characteristics 13
2112 Preparation of membrane 13
2113 Hydraulic cleaning of membranes 14
2114 Flux recovery 14
212 Batch tests for zeta potential titration 14
213 Jar tests 15
214 Specific resistance and cake compressibility 15
215 Critical flux determination 18
2151 Sample pretreatment 18
2152 Microfiltration process 19
216 Multi-cycle filtration test 20
2161 Sample preparation 20
2162 Microfiltration process 20
217 Dead end microfiltration test 22
CHAPTER 3 IMPACT OF POLYMERS ON COAGULATION OF LAUNDRY
WASTEWATER 23
31 Batch tests 24
32 Jar tests 26
33 Specific resistance to filtration and cake compressibility 29
34 Summary 33
CHAPTER 4 IN-LINE COAGULATION AND MF CRITICAL FLUX AND
LONG-TERM MF OPERATION 34
41 Jar tests identifying dosing regimes 35
42 Critical Fluxes for the dosing regimes 36
43 Multi-cycle constant flux MF experiments 39
VII
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation 44
45 Contaminant removals in bench scale MF experiments 46
45 Summary 47
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE SHOWER WASTEWATER
REUSE SYSTEM 48
51 SWRS description 50
511 System overview 50
512 Microfiltration characteristics 53
513 RO filter 53
514 Chemical injection system 53
515 Air system 54
516 GAC filter and UV light 54
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy 54
52 SWRS setup and dosing strategy at Penn State Laundry Building 54
53 SWRS operation at various microfiltration permeate flux with clean
water 56
54 Results of long-term SWRS operation 57
55 Water quality changes 60
56 SWRS operation problems 61
561 Pre-filter fouling 61
562 RO scaling 61
563 Other problems 62
57 Hypotheses regarding differences between bench-scale experiments and
full-scale tests 62
VIII
571 Water quality 62
572 Pre-filter sequence 62
573 Cross-flow and backwash 62
574 Coagulated lint particle in the settlement 63
58 Additional multi-cycle bench-scale microfiltration tests on Penn State
laundry wastewater 63
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis 65
591 RO fouling during operation 65
592 RO membrane autopsy and sample preparation 65
593 SEM images 65
594 EDS analysis 66
595 TEM images 72
596 RO cleaning and cleaning solutions 74
597 Cleaning solution analysis 75
510 Summary 76
CHAPTER 6 CONCLUSIONS 77
61 Polymer selection for laundry wastewater treatment 77
62 Bench scale MF experiments 77
63 Full-scale tests and RO scaling 79
CHAPTER 7 RECOMMENDATIONS 80
REFERENCES 81
Appendix A Material and Water Quality changes in Bench Scale Experiments 86
Appendix B Example of Data Processing for Critical Flux Determination Experiment
100
Appendix C Example of Data Processing for a Multi-cycle Membrane Filtration
Experiment 104
IX
Appendix D Images of SWRS Components and Hose Connection 110
Appendix E Water Quality During SWRS Operation 112
Appendix F SWRS Backwash Strategy without Starting the High Pressure Pump 116
Appendix G RO Fouling Report 117
X
LIST OF FIGURES
Figure 21 Schematic diagram of critical flux determination setup 20
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane
filtration test (By Dr Hyunchul Kim) 21
Figure 23 Schematic diagram of dead-end microfiltration experimental setup 22
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH
108 25
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different
pH conditions (pH 72 on the left side) and (pH 11 on the right side)
using five polymers 28
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope)
during the membrane (022 microm PVDF) filtration of raw and coagulated
lint wastewaters (22ordmC) Two different coagulation regimes for each
polymer were employed ie charge-neutralizing (ZP between plusmn5 mV
and highest turbidity removal) and underdosing (more negative ZP
value and relatively poorer contaminant removal) conditions 32
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using
NALCOLYTE 8105 as the coagulant at pH 11 35
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux
determination after various pre-treatment by coagulation with
NALCOLYTE 8105 at pH 11 and constant temperature of 40 ˚C
Permeate flux was constant for 10 min and increased stepwise 38
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for charge
neutralization condition at pH 11 and constant temperature of 40 ˚C 40
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30
III
ABSTRACT
Membrane filtration has been widely employed for treating potable water and wastewater
This thesis dealt with the use of microfiltration (MF) for treatment and reuse of laundry
wastewater The most important issues with respect to laundry water reuse are treated
water quality membrane fouling and cost and energy consumption Only the first two of
these issues were addressed in this thesis This thesis was focused on developing
methods to improve performance of the Armyrsquos full-scale Shower Water Reuse System
(SWRS) specifically for treating and reusing laundry wastewater The SWRS uses
pretreatment with pre- filtration (15 microm steel mesh) MF (02 microm PVDF) reverse osmosis
(RO) and Granular activated carbon (GAC) Based on the information from the Army
and their contractors the major problem in using the SWRS for laundry wastewater was
fouling of the MF Therefore the objectives were to investigate the effects of coagulants
for improving MF performance and for removal of contaminants
Coagulation has been used prior to MF for decreasing membrane fouling enhancing
MF flux and improving removal of contaminants There are problems in employing
conventional coagulants (eg alum and ferric chloride) for treating laundry wastewater due
to the difficulties in achieving effective coagulation at high pH high total suspended solids
(TSS) and high chemical oxygen demand (COD) In particular the very high doses of
inorganic coagulants that are required for these water quality conditions result in voluminous
sludge production which is inappropriate prior to membrane treatment As a result cationic
polyelectrolytes were investigated
The effects of different cationic polymers on laundry wastewater treatment were first
investigated using batch coagulationprecipitation with sedimentation (without membrane
filtration) evaluating Zeta Potential (ZP) changes and removal of COD TSS turbidity and
total phosphorus (TP) Subsequently the influence of cationic polymers on MF performance
was studied by measuring specific resistance and cake compressibility Based on these initial
experiments a commercial poly-quaternary amine containing epichlorohydrin
dimethylamine (Epi-DMA) was selected as the best polymer based on successful
neutralization of contaminant charge and low specific resistance on polyvinylidine
fluoride (PVDF) MF over a broad range of pH and coagulant dose The initial
experiments also demonstrated that Epi-DMA was effective for removal of contaminants
IV
after sedimentation eg 63 of COD 77 of TSS 96 of turbidity and 26 of TP
were removed
Subsequent bench-scale experiments focused on evaluating the effects of Epi-DMA
on reducing membrane fouling and increasing critical flux defined as the maximum flux
for which trans-membrane pressure (TMP) increased linearly with permeate flux Epi-
DMA coagulation significantly increased the critical flux from 50 L m-2h-1 for the raw
sample to 510 L m-2h-1 for the charge neutralization (CN) condition Epi-DMA additions
also substantially decreased resistance to filtration over a broad range of coagulant doses
including doses less than 50 of that required for CN
The effects of Epi-DMA on MF of laundry wastewater were further investigated by
conducting multi-cycle tests with backwashing every 15 min These bench-scale
experiments were run at 50 L m-2h-1 which is a typical membrane flux used in full-scale
MF operations The multi-cycle experiments demonstrated that increases in the trans-
membrane pressure (TMP) that occurred during each cycle were nearly eliminated by the
backwash for under-dosing (UD) and CN conditions but that TMP increases during over-
dosing (OD) coagulation conditions were not eliminated during backwash
Finally the use of Epi-DMA was tested on the full-scale SWRS which was set up
outside the Penn State laundry facility The setup included two 3000 gal bladders
Laundry wastewater was pumped from the laundry facility into the bladders and Epi-
DMA was introduced into the bladders prior to the pre-treatment The effects on the
down-stream membrane units were investigated The tests were performed over a range
of Epi-DMA doses including no coagulant UD CN and OD The tests demonstrated
that negligible fouling of the MF occurred but serious fouling was observed in the RO
unit Formation of inorganic precipitates was suspected as the main reason for RO failure
The full-scale MF without coagulant did not foul as much as the bench-scale MF
experiments had indicated This could have been due to more rigorous backwashing with
the SWRS or due to retention of partially coagulated solids in the bladders despite inter-
experiment flushing with tap water Issues regarding MF and RO behavior in the full-
scale SWRS are currently under investigation and some conclusions are reported in this
thesis
V
TABLE OF CONTENTS
LIST OF FIGURES X
LIST OF TABLES XIV
ACKNOWLEDGEMENTS XVI
DEDICATION XVII
ABBREVIATIONS XVIII
CHAPTER 1 INTRODUCTION 1
11 Project background 1
12 Objectives 4
13 Organization of the thesis 5
CHAPTER 2 MATERIALS AND METHODS 7
21 Laundry wastewater description 7
22 Zeta potential (COD TSS Turbidity TP) 8
221 Zeta Sizer Nano series 8
222 Zeta Compact 9
22 DI water 9
23 pH and conductivity 9
24 Total suspended solids 9
25 COD and Total phosphorus 9
26 Turbidity 10
27 SEM 10
28 TEM 10
29 Particle size distribution and particle images 10
210 Polymeric coagulants 11
VI
211 Membranes 13
2111 Membrane characteristics 13
2112 Preparation of membrane 13
2113 Hydraulic cleaning of membranes 14
2114 Flux recovery 14
212 Batch tests for zeta potential titration 14
213 Jar tests 15
214 Specific resistance and cake compressibility 15
215 Critical flux determination 18
2151 Sample pretreatment 18
2152 Microfiltration process 19
216 Multi-cycle filtration test 20
2161 Sample preparation 20
2162 Microfiltration process 20
217 Dead end microfiltration test 22
CHAPTER 3 IMPACT OF POLYMERS ON COAGULATION OF LAUNDRY
WASTEWATER 23
31 Batch tests 24
32 Jar tests 26
33 Specific resistance to filtration and cake compressibility 29
34 Summary 33
CHAPTER 4 IN-LINE COAGULATION AND MF CRITICAL FLUX AND
LONG-TERM MF OPERATION 34
41 Jar tests identifying dosing regimes 35
42 Critical Fluxes for the dosing regimes 36
43 Multi-cycle constant flux MF experiments 39
VII
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation 44
45 Contaminant removals in bench scale MF experiments 46
45 Summary 47
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE SHOWER WASTEWATER
REUSE SYSTEM 48
51 SWRS description 50
511 System overview 50
512 Microfiltration characteristics 53
513 RO filter 53
514 Chemical injection system 53
515 Air system 54
516 GAC filter and UV light 54
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy 54
52 SWRS setup and dosing strategy at Penn State Laundry Building 54
53 SWRS operation at various microfiltration permeate flux with clean
water 56
54 Results of long-term SWRS operation 57
55 Water quality changes 60
56 SWRS operation problems 61
561 Pre-filter fouling 61
562 RO scaling 61
563 Other problems 62
57 Hypotheses regarding differences between bench-scale experiments and
full-scale tests 62
VIII
571 Water quality 62
572 Pre-filter sequence 62
573 Cross-flow and backwash 62
574 Coagulated lint particle in the settlement 63
58 Additional multi-cycle bench-scale microfiltration tests on Penn State
laundry wastewater 63
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis 65
591 RO fouling during operation 65
592 RO membrane autopsy and sample preparation 65
593 SEM images 65
594 EDS analysis 66
595 TEM images 72
596 RO cleaning and cleaning solutions 74
597 Cleaning solution analysis 75
510 Summary 76
CHAPTER 6 CONCLUSIONS 77
61 Polymer selection for laundry wastewater treatment 77
62 Bench scale MF experiments 77
63 Full-scale tests and RO scaling 79
CHAPTER 7 RECOMMENDATIONS 80
REFERENCES 81
Appendix A Material and Water Quality changes in Bench Scale Experiments 86
Appendix B Example of Data Processing for Critical Flux Determination Experiment
100
Appendix C Example of Data Processing for a Multi-cycle Membrane Filtration
Experiment 104
IX
Appendix D Images of SWRS Components and Hose Connection 110
Appendix E Water Quality During SWRS Operation 112
Appendix F SWRS Backwash Strategy without Starting the High Pressure Pump 116
Appendix G RO Fouling Report 117
X
LIST OF FIGURES
Figure 21 Schematic diagram of critical flux determination setup 20
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane
filtration test (By Dr Hyunchul Kim) 21
Figure 23 Schematic diagram of dead-end microfiltration experimental setup 22
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH
108 25
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different
pH conditions (pH 72 on the left side) and (pH 11 on the right side)
using five polymers 28
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope)
during the membrane (022 microm PVDF) filtration of raw and coagulated
lint wastewaters (22ordmC) Two different coagulation regimes for each
polymer were employed ie charge-neutralizing (ZP between plusmn5 mV
and highest turbidity removal) and underdosing (more negative ZP
value and relatively poorer contaminant removal) conditions 32
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using
NALCOLYTE 8105 as the coagulant at pH 11 35
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux
determination after various pre-treatment by coagulation with
NALCOLYTE 8105 at pH 11 and constant temperature of 40 ˚C
Permeate flux was constant for 10 min and increased stepwise 38
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for charge
neutralization condition at pH 11 and constant temperature of 40 ˚C 40
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30
IV
after sedimentation eg 63 of COD 77 of TSS 96 of turbidity and 26 of TP
were removed
Subsequent bench-scale experiments focused on evaluating the effects of Epi-DMA
on reducing membrane fouling and increasing critical flux defined as the maximum flux
for which trans-membrane pressure (TMP) increased linearly with permeate flux Epi-
DMA coagulation significantly increased the critical flux from 50 L m-2h-1 for the raw
sample to 510 L m-2h-1 for the charge neutralization (CN) condition Epi-DMA additions
also substantially decreased resistance to filtration over a broad range of coagulant doses
including doses less than 50 of that required for CN
The effects of Epi-DMA on MF of laundry wastewater were further investigated by
conducting multi-cycle tests with backwashing every 15 min These bench-scale
experiments were run at 50 L m-2h-1 which is a typical membrane flux used in full-scale
MF operations The multi-cycle experiments demonstrated that increases in the trans-
membrane pressure (TMP) that occurred during each cycle were nearly eliminated by the
backwash for under-dosing (UD) and CN conditions but that TMP increases during over-
dosing (OD) coagulation conditions were not eliminated during backwash
Finally the use of Epi-DMA was tested on the full-scale SWRS which was set up
outside the Penn State laundry facility The setup included two 3000 gal bladders
Laundry wastewater was pumped from the laundry facility into the bladders and Epi-
DMA was introduced into the bladders prior to the pre-treatment The effects on the
down-stream membrane units were investigated The tests were performed over a range
of Epi-DMA doses including no coagulant UD CN and OD The tests demonstrated
that negligible fouling of the MF occurred but serious fouling was observed in the RO
unit Formation of inorganic precipitates was suspected as the main reason for RO failure
The full-scale MF without coagulant did not foul as much as the bench-scale MF
experiments had indicated This could have been due to more rigorous backwashing with
the SWRS or due to retention of partially coagulated solids in the bladders despite inter-
experiment flushing with tap water Issues regarding MF and RO behavior in the full-
scale SWRS are currently under investigation and some conclusions are reported in this
thesis
V
TABLE OF CONTENTS
LIST OF FIGURES X
LIST OF TABLES XIV
ACKNOWLEDGEMENTS XVI
DEDICATION XVII
ABBREVIATIONS XVIII
CHAPTER 1 INTRODUCTION 1
11 Project background 1
12 Objectives 4
13 Organization of the thesis 5
CHAPTER 2 MATERIALS AND METHODS 7
21 Laundry wastewater description 7
22 Zeta potential (COD TSS Turbidity TP) 8
221 Zeta Sizer Nano series 8
222 Zeta Compact 9
22 DI water 9
23 pH and conductivity 9
24 Total suspended solids 9
25 COD and Total phosphorus 9
26 Turbidity 10
27 SEM 10
28 TEM 10
29 Particle size distribution and particle images 10
210 Polymeric coagulants 11
VI
211 Membranes 13
2111 Membrane characteristics 13
2112 Preparation of membrane 13
2113 Hydraulic cleaning of membranes 14
2114 Flux recovery 14
212 Batch tests for zeta potential titration 14
213 Jar tests 15
214 Specific resistance and cake compressibility 15
215 Critical flux determination 18
2151 Sample pretreatment 18
2152 Microfiltration process 19
216 Multi-cycle filtration test 20
2161 Sample preparation 20
2162 Microfiltration process 20
217 Dead end microfiltration test 22
CHAPTER 3 IMPACT OF POLYMERS ON COAGULATION OF LAUNDRY
WASTEWATER 23
31 Batch tests 24
32 Jar tests 26
33 Specific resistance to filtration and cake compressibility 29
34 Summary 33
CHAPTER 4 IN-LINE COAGULATION AND MF CRITICAL FLUX AND
LONG-TERM MF OPERATION 34
41 Jar tests identifying dosing regimes 35
42 Critical Fluxes for the dosing regimes 36
43 Multi-cycle constant flux MF experiments 39
VII
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation 44
45 Contaminant removals in bench scale MF experiments 46
45 Summary 47
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE SHOWER WASTEWATER
REUSE SYSTEM 48
51 SWRS description 50
511 System overview 50
512 Microfiltration characteristics 53
513 RO filter 53
514 Chemical injection system 53
515 Air system 54
516 GAC filter and UV light 54
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy 54
52 SWRS setup and dosing strategy at Penn State Laundry Building 54
53 SWRS operation at various microfiltration permeate flux with clean
water 56
54 Results of long-term SWRS operation 57
55 Water quality changes 60
56 SWRS operation problems 61
561 Pre-filter fouling 61
562 RO scaling 61
563 Other problems 62
57 Hypotheses regarding differences between bench-scale experiments and
full-scale tests 62
VIII
571 Water quality 62
572 Pre-filter sequence 62
573 Cross-flow and backwash 62
574 Coagulated lint particle in the settlement 63
58 Additional multi-cycle bench-scale microfiltration tests on Penn State
laundry wastewater 63
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis 65
591 RO fouling during operation 65
592 RO membrane autopsy and sample preparation 65
593 SEM images 65
594 EDS analysis 66
595 TEM images 72
596 RO cleaning and cleaning solutions 74
597 Cleaning solution analysis 75
510 Summary 76
CHAPTER 6 CONCLUSIONS 77
61 Polymer selection for laundry wastewater treatment 77
62 Bench scale MF experiments 77
63 Full-scale tests and RO scaling 79
CHAPTER 7 RECOMMENDATIONS 80
REFERENCES 81
Appendix A Material and Water Quality changes in Bench Scale Experiments 86
Appendix B Example of Data Processing for Critical Flux Determination Experiment
100
Appendix C Example of Data Processing for a Multi-cycle Membrane Filtration
Experiment 104
IX
Appendix D Images of SWRS Components and Hose Connection 110
Appendix E Water Quality During SWRS Operation 112
Appendix F SWRS Backwash Strategy without Starting the High Pressure Pump 116
Appendix G RO Fouling Report 117
X
LIST OF FIGURES
Figure 21 Schematic diagram of critical flux determination setup 20
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane
filtration test (By Dr Hyunchul Kim) 21
Figure 23 Schematic diagram of dead-end microfiltration experimental setup 22
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH
108 25
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different
pH conditions (pH 72 on the left side) and (pH 11 on the right side)
using five polymers 28
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope)
during the membrane (022 microm PVDF) filtration of raw and coagulated
lint wastewaters (22ordmC) Two different coagulation regimes for each
polymer were employed ie charge-neutralizing (ZP between plusmn5 mV
and highest turbidity removal) and underdosing (more negative ZP
value and relatively poorer contaminant removal) conditions 32
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using
NALCOLYTE 8105 as the coagulant at pH 11 35
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux
determination after various pre-treatment by coagulation with
NALCOLYTE 8105 at pH 11 and constant temperature of 40 ˚C
Permeate flux was constant for 10 min and increased stepwise 38
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for charge
neutralization condition at pH 11 and constant temperature of 40 ˚C 40
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30
V
TABLE OF CONTENTS
LIST OF FIGURES X
LIST OF TABLES XIV
ACKNOWLEDGEMENTS XVI
DEDICATION XVII
ABBREVIATIONS XVIII
CHAPTER 1 INTRODUCTION 1
11 Project background 1
12 Objectives 4
13 Organization of the thesis 5
CHAPTER 2 MATERIALS AND METHODS 7
21 Laundry wastewater description 7
22 Zeta potential (COD TSS Turbidity TP) 8
221 Zeta Sizer Nano series 8
222 Zeta Compact 9
22 DI water 9
23 pH and conductivity 9
24 Total suspended solids 9
25 COD and Total phosphorus 9
26 Turbidity 10
27 SEM 10
28 TEM 10
29 Particle size distribution and particle images 10
210 Polymeric coagulants 11
VI
211 Membranes 13
2111 Membrane characteristics 13
2112 Preparation of membrane 13
2113 Hydraulic cleaning of membranes 14
2114 Flux recovery 14
212 Batch tests for zeta potential titration 14
213 Jar tests 15
214 Specific resistance and cake compressibility 15
215 Critical flux determination 18
2151 Sample pretreatment 18
2152 Microfiltration process 19
216 Multi-cycle filtration test 20
2161 Sample preparation 20
2162 Microfiltration process 20
217 Dead end microfiltration test 22
CHAPTER 3 IMPACT OF POLYMERS ON COAGULATION OF LAUNDRY
WASTEWATER 23
31 Batch tests 24
32 Jar tests 26
33 Specific resistance to filtration and cake compressibility 29
34 Summary 33
CHAPTER 4 IN-LINE COAGULATION AND MF CRITICAL FLUX AND
LONG-TERM MF OPERATION 34
41 Jar tests identifying dosing regimes 35
42 Critical Fluxes for the dosing regimes 36
43 Multi-cycle constant flux MF experiments 39
VII
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation 44
45 Contaminant removals in bench scale MF experiments 46
45 Summary 47
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE SHOWER WASTEWATER
REUSE SYSTEM 48
51 SWRS description 50
511 System overview 50
512 Microfiltration characteristics 53
513 RO filter 53
514 Chemical injection system 53
515 Air system 54
516 GAC filter and UV light 54
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy 54
52 SWRS setup and dosing strategy at Penn State Laundry Building 54
53 SWRS operation at various microfiltration permeate flux with clean
water 56
54 Results of long-term SWRS operation 57
55 Water quality changes 60
56 SWRS operation problems 61
561 Pre-filter fouling 61
562 RO scaling 61
563 Other problems 62
57 Hypotheses regarding differences between bench-scale experiments and
full-scale tests 62
VIII
571 Water quality 62
572 Pre-filter sequence 62
573 Cross-flow and backwash 62
574 Coagulated lint particle in the settlement 63
58 Additional multi-cycle bench-scale microfiltration tests on Penn State
laundry wastewater 63
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis 65
591 RO fouling during operation 65
592 RO membrane autopsy and sample preparation 65
593 SEM images 65
594 EDS analysis 66
595 TEM images 72
596 RO cleaning and cleaning solutions 74
597 Cleaning solution analysis 75
510 Summary 76
CHAPTER 6 CONCLUSIONS 77
61 Polymer selection for laundry wastewater treatment 77
62 Bench scale MF experiments 77
63 Full-scale tests and RO scaling 79
CHAPTER 7 RECOMMENDATIONS 80
REFERENCES 81
Appendix A Material and Water Quality changes in Bench Scale Experiments 86
Appendix B Example of Data Processing for Critical Flux Determination Experiment
100
Appendix C Example of Data Processing for a Multi-cycle Membrane Filtration
Experiment 104
IX
Appendix D Images of SWRS Components and Hose Connection 110
Appendix E Water Quality During SWRS Operation 112
Appendix F SWRS Backwash Strategy without Starting the High Pressure Pump 116
Appendix G RO Fouling Report 117
X
LIST OF FIGURES
Figure 21 Schematic diagram of critical flux determination setup 20
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane
filtration test (By Dr Hyunchul Kim) 21
Figure 23 Schematic diagram of dead-end microfiltration experimental setup 22
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH
108 25
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different
pH conditions (pH 72 on the left side) and (pH 11 on the right side)
using five polymers 28
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope)
during the membrane (022 microm PVDF) filtration of raw and coagulated
lint wastewaters (22ordmC) Two different coagulation regimes for each
polymer were employed ie charge-neutralizing (ZP between plusmn5 mV
and highest turbidity removal) and underdosing (more negative ZP
value and relatively poorer contaminant removal) conditions 32
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using
NALCOLYTE 8105 as the coagulant at pH 11 35
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux
determination after various pre-treatment by coagulation with
NALCOLYTE 8105 at pH 11 and constant temperature of 40 ˚C
Permeate flux was constant for 10 min and increased stepwise 38
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for charge
neutralization condition at pH 11 and constant temperature of 40 ˚C 40
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30
VI
211 Membranes 13
2111 Membrane characteristics 13
2112 Preparation of membrane 13
2113 Hydraulic cleaning of membranes 14
2114 Flux recovery 14
212 Batch tests for zeta potential titration 14
213 Jar tests 15
214 Specific resistance and cake compressibility 15
215 Critical flux determination 18
2151 Sample pretreatment 18
2152 Microfiltration process 19
216 Multi-cycle filtration test 20
2161 Sample preparation 20
2162 Microfiltration process 20
217 Dead end microfiltration test 22
CHAPTER 3 IMPACT OF POLYMERS ON COAGULATION OF LAUNDRY
WASTEWATER 23
31 Batch tests 24
32 Jar tests 26
33 Specific resistance to filtration and cake compressibility 29
34 Summary 33
CHAPTER 4 IN-LINE COAGULATION AND MF CRITICAL FLUX AND
LONG-TERM MF OPERATION 34
41 Jar tests identifying dosing regimes 35
42 Critical Fluxes for the dosing regimes 36
43 Multi-cycle constant flux MF experiments 39
VII
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation 44
45 Contaminant removals in bench scale MF experiments 46
45 Summary 47
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE SHOWER WASTEWATER
REUSE SYSTEM 48
51 SWRS description 50
511 System overview 50
512 Microfiltration characteristics 53
513 RO filter 53
514 Chemical injection system 53
515 Air system 54
516 GAC filter and UV light 54
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy 54
52 SWRS setup and dosing strategy at Penn State Laundry Building 54
53 SWRS operation at various microfiltration permeate flux with clean
water 56
54 Results of long-term SWRS operation 57
55 Water quality changes 60
56 SWRS operation problems 61
561 Pre-filter fouling 61
562 RO scaling 61
563 Other problems 62
57 Hypotheses regarding differences between bench-scale experiments and
full-scale tests 62
VIII
571 Water quality 62
572 Pre-filter sequence 62
573 Cross-flow and backwash 62
574 Coagulated lint particle in the settlement 63
58 Additional multi-cycle bench-scale microfiltration tests on Penn State
laundry wastewater 63
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis 65
591 RO fouling during operation 65
592 RO membrane autopsy and sample preparation 65
593 SEM images 65
594 EDS analysis 66
595 TEM images 72
596 RO cleaning and cleaning solutions 74
597 Cleaning solution analysis 75
510 Summary 76
CHAPTER 6 CONCLUSIONS 77
61 Polymer selection for laundry wastewater treatment 77
62 Bench scale MF experiments 77
63 Full-scale tests and RO scaling 79
CHAPTER 7 RECOMMENDATIONS 80
REFERENCES 81
Appendix A Material and Water Quality changes in Bench Scale Experiments 86
Appendix B Example of Data Processing for Critical Flux Determination Experiment
100
Appendix C Example of Data Processing for a Multi-cycle Membrane Filtration
Experiment 104
IX
Appendix D Images of SWRS Components and Hose Connection 110
Appendix E Water Quality During SWRS Operation 112
Appendix F SWRS Backwash Strategy without Starting the High Pressure Pump 116
Appendix G RO Fouling Report 117
X
LIST OF FIGURES
Figure 21 Schematic diagram of critical flux determination setup 20
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane
filtration test (By Dr Hyunchul Kim) 21
Figure 23 Schematic diagram of dead-end microfiltration experimental setup 22
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH
108 25
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different
pH conditions (pH 72 on the left side) and (pH 11 on the right side)
using five polymers 28
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope)
during the membrane (022 microm PVDF) filtration of raw and coagulated
lint wastewaters (22ordmC) Two different coagulation regimes for each
polymer were employed ie charge-neutralizing (ZP between plusmn5 mV
and highest turbidity removal) and underdosing (more negative ZP
value and relatively poorer contaminant removal) conditions 32
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using
NALCOLYTE 8105 as the coagulant at pH 11 35
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux
determination after various pre-treatment by coagulation with
NALCOLYTE 8105 at pH 11 and constant temperature of 40 ˚C
Permeate flux was constant for 10 min and increased stepwise 38
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for charge
neutralization condition at pH 11 and constant temperature of 40 ˚C 40
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30
VII
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation 44
45 Contaminant removals in bench scale MF experiments 46
45 Summary 47
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE SHOWER WASTEWATER
REUSE SYSTEM 48
51 SWRS description 50
511 System overview 50
512 Microfiltration characteristics 53
513 RO filter 53
514 Chemical injection system 53
515 Air system 54
516 GAC filter and UV light 54
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy 54
52 SWRS setup and dosing strategy at Penn State Laundry Building 54
53 SWRS operation at various microfiltration permeate flux with clean
water 56
54 Results of long-term SWRS operation 57
55 Water quality changes 60
56 SWRS operation problems 61
561 Pre-filter fouling 61
562 RO scaling 61
563 Other problems 62
57 Hypotheses regarding differences between bench-scale experiments and
full-scale tests 62
VIII
571 Water quality 62
572 Pre-filter sequence 62
573 Cross-flow and backwash 62
574 Coagulated lint particle in the settlement 63
58 Additional multi-cycle bench-scale microfiltration tests on Penn State
laundry wastewater 63
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis 65
591 RO fouling during operation 65
592 RO membrane autopsy and sample preparation 65
593 SEM images 65
594 EDS analysis 66
595 TEM images 72
596 RO cleaning and cleaning solutions 74
597 Cleaning solution analysis 75
510 Summary 76
CHAPTER 6 CONCLUSIONS 77
61 Polymer selection for laundry wastewater treatment 77
62 Bench scale MF experiments 77
63 Full-scale tests and RO scaling 79
CHAPTER 7 RECOMMENDATIONS 80
REFERENCES 81
Appendix A Material and Water Quality changes in Bench Scale Experiments 86
Appendix B Example of Data Processing for Critical Flux Determination Experiment
100
Appendix C Example of Data Processing for a Multi-cycle Membrane Filtration
Experiment 104
IX
Appendix D Images of SWRS Components and Hose Connection 110
Appendix E Water Quality During SWRS Operation 112
Appendix F SWRS Backwash Strategy without Starting the High Pressure Pump 116
Appendix G RO Fouling Report 117
X
LIST OF FIGURES
Figure 21 Schematic diagram of critical flux determination setup 20
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane
filtration test (By Dr Hyunchul Kim) 21
Figure 23 Schematic diagram of dead-end microfiltration experimental setup 22
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH
108 25
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different
pH conditions (pH 72 on the left side) and (pH 11 on the right side)
using five polymers 28
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope)
during the membrane (022 microm PVDF) filtration of raw and coagulated
lint wastewaters (22ordmC) Two different coagulation regimes for each
polymer were employed ie charge-neutralizing (ZP between plusmn5 mV
and highest turbidity removal) and underdosing (more negative ZP
value and relatively poorer contaminant removal) conditions 32
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using
NALCOLYTE 8105 as the coagulant at pH 11 35
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux
determination after various pre-treatment by coagulation with
NALCOLYTE 8105 at pH 11 and constant temperature of 40 ˚C
Permeate flux was constant for 10 min and increased stepwise 38
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for charge
neutralization condition at pH 11 and constant temperature of 40 ˚C 40
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30
VIII
571 Water quality 62
572 Pre-filter sequence 62
573 Cross-flow and backwash 62
574 Coagulated lint particle in the settlement 63
58 Additional multi-cycle bench-scale microfiltration tests on Penn State
laundry wastewater 63
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis 65
591 RO fouling during operation 65
592 RO membrane autopsy and sample preparation 65
593 SEM images 65
594 EDS analysis 66
595 TEM images 72
596 RO cleaning and cleaning solutions 74
597 Cleaning solution analysis 75
510 Summary 76
CHAPTER 6 CONCLUSIONS 77
61 Polymer selection for laundry wastewater treatment 77
62 Bench scale MF experiments 77
63 Full-scale tests and RO scaling 79
CHAPTER 7 RECOMMENDATIONS 80
REFERENCES 81
Appendix A Material and Water Quality changes in Bench Scale Experiments 86
Appendix B Example of Data Processing for Critical Flux Determination Experiment
100
Appendix C Example of Data Processing for a Multi-cycle Membrane Filtration
Experiment 104
IX
Appendix D Images of SWRS Components and Hose Connection 110
Appendix E Water Quality During SWRS Operation 112
Appendix F SWRS Backwash Strategy without Starting the High Pressure Pump 116
Appendix G RO Fouling Report 117
X
LIST OF FIGURES
Figure 21 Schematic diagram of critical flux determination setup 20
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane
filtration test (By Dr Hyunchul Kim) 21
Figure 23 Schematic diagram of dead-end microfiltration experimental setup 22
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH
108 25
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different
pH conditions (pH 72 on the left side) and (pH 11 on the right side)
using five polymers 28
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope)
during the membrane (022 microm PVDF) filtration of raw and coagulated
lint wastewaters (22ordmC) Two different coagulation regimes for each
polymer were employed ie charge-neutralizing (ZP between plusmn5 mV
and highest turbidity removal) and underdosing (more negative ZP
value and relatively poorer contaminant removal) conditions 32
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using
NALCOLYTE 8105 as the coagulant at pH 11 35
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux
determination after various pre-treatment by coagulation with
NALCOLYTE 8105 at pH 11 and constant temperature of 40 ˚C
Permeate flux was constant for 10 min and increased stepwise 38
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for charge
neutralization condition at pH 11 and constant temperature of 40 ˚C 40
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30
IX
Appendix D Images of SWRS Components and Hose Connection 110
Appendix E Water Quality During SWRS Operation 112
Appendix F SWRS Backwash Strategy without Starting the High Pressure Pump 116
Appendix G RO Fouling Report 117
X
LIST OF FIGURES
Figure 21 Schematic diagram of critical flux determination setup 20
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane
filtration test (By Dr Hyunchul Kim) 21
Figure 23 Schematic diagram of dead-end microfiltration experimental setup 22
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH
108 25
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different
pH conditions (pH 72 on the left side) and (pH 11 on the right side)
using five polymers 28
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope)
during the membrane (022 microm PVDF) filtration of raw and coagulated
lint wastewaters (22ordmC) Two different coagulation regimes for each
polymer were employed ie charge-neutralizing (ZP between plusmn5 mV
and highest turbidity removal) and underdosing (more negative ZP
value and relatively poorer contaminant removal) conditions 32
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using
NALCOLYTE 8105 as the coagulant at pH 11 35
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux
determination after various pre-treatment by coagulation with
NALCOLYTE 8105 at pH 11 and constant temperature of 40 ˚C
Permeate flux was constant for 10 min and increased stepwise 38
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for charge
neutralization condition at pH 11 and constant temperature of 40 ˚C 40
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30
X
LIST OF FIGURES
Figure 21 Schematic diagram of critical flux determination setup 20
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane
filtration test (By Dr Hyunchul Kim) 21
Figure 23 Schematic diagram of dead-end microfiltration experimental setup 22
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH
108 25
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different
pH conditions (pH 72 on the left side) and (pH 11 on the right side)
using five polymers 28
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope)
during the membrane (022 microm PVDF) filtration of raw and coagulated
lint wastewaters (22ordmC) Two different coagulation regimes for each
polymer were employed ie charge-neutralizing (ZP between plusmn5 mV
and highest turbidity removal) and underdosing (more negative ZP
value and relatively poorer contaminant removal) conditions 32
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using
NALCOLYTE 8105 as the coagulant at pH 11 35
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux
determination after various pre-treatment by coagulation with
NALCOLYTE 8105 at pH 11 and constant temperature of 40 ˚C
Permeate flux was constant for 10 min and increased stepwise 38
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for charge
neutralization condition at pH 11 and constant temperature of 40 ˚C 40
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30
XI
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration
(022microm) for ten cycles at various constant permeate flux of polymer
pre-treated laundry lint wastewater with NALCOLYTE 8105 for
overdosing condition at pH 11 and constant temperature of 40 ˚C 41
Figure 45 Transmembrane pressure to permeate volume in the PVDF
microfiltration (022microm) for ten cycles at various constant permeate
flux of polymer pre-treated laundry lint wastewater with NALCOLYTE
8105 for underdosing condition at pH 11 and constant temperature of
40 ˚C 42
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration
(022microm) for multi-cycles at various constant permeate flux for raw
laundry wastewater at pH 11 and constant temperature of 40 ˚C 43
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm)
for ten cycles at 50 L m-2h-1 of polymer pre-treated laundry lint
wastewater with NALCOLYTE 8105 for zero-dosing underdosing
charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C 44
Figure 48 Contaminant removal () for different treatment methods (pre-filtration
MF and the suspension collected after coagulation and precipitation)
and different dosing conditions on Cintas laundry wastewater 46
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State
University 50
Figure 52 SWRS flowchart under standard operation 52
Figure 53 SWRS front site overview and the main treating components 52
Figure 54 SWRS set-up at Penn State Laundry Building 55
Figure 55 Hose connection a sequential way used in Penn State Laundry
wastewater treatment by SWRS The SWRS unit is on treatment with
wastewater in Bladder 2 which has been coagulated before and
bladder 1 is filling with laundry wastewater at the same time 56
XII
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS
operation using tap water 57
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1120 gpm using tap water 58
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a
constant permeate flow rate of 1055 gpm using tap water 58
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using
laundry wastewater when the flow rate declined due to the fouling on
the mesh filter 59
Figure 510 Contaminants residual and water quality changes during SWRS
operation 60
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10
μm mesh filter after coagulation 64
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k
x b) 10 kx 67
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583
kx d) 845 kx 68
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311
kx d) 612 kx 69
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx
b) 938 kx 70
Figure 516 SEM images of the fouled RO membrane where there may have been
less fouling a) 574 kx d) 1157 kx The membrane was pre-treated by
Au sputtering 71
Figure 517 TEM images of the cross-section of the fouled RO membrane 73
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and
chemical injection pump controller c) MF d) RO vessels 110
XIII
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of
the sump pump from Laundry Building c) hose connection to two 3K
bladders d) 3K bladders and SWRS unit 111
XIV
LIST OF TABLES
Table 21 General characteristics of the laundry wastewater in this study 7
Table 22 The characteristics of polymers provided by manufacturers 12
Table 23 Membrane properties used in this study 13
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11
for the five polymers used in the jar tests 29
Table 51 RO cleaning solution and cleaning procedures for sample being shipped 74
Table 52 Concentration of the inorganic elements left in the cleaning solution after
the fouled RO membrane was cleaned 75
Table A1 General characteristics of membranes (Stephenson et al 2000) 86
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments 86
Table A3 Polymers from Cintas Company 87
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater 88
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 Plus in treating Penn State Laundry Wastewater 89
Table A6 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 90
Table A7 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 91
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 92
Table A9 Data obtained from the coagulationprecipitation experiment by
ULTIMER 1460 in treating Cintas Laundry Wastewater 93
XV
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater 94
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-
FLOC 8108 PLUS in treating Cintas Laundry Wastewater 95
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater 96
Table A13 Data obtained from the coagulationprecipitation experiment by NACO
2490 in treating Cintas Laundry Wastewater 97
Table A14 Data obtained from the coagulationprecipitation experiment by
NALCOLYTE 8105 in treating Cintas Laundry Wastewater 99
Table B1 Data processing for critical flux determination experiment 101
Table C2 Data processing for multi-cycle membrane experiments 105
Table E1 Water quality changes by coagulation MF RO and finished water 112
Table E2 Water quality changes by MF in SWRS operation (1) 113
Table E3 Water quality changes by MF in SWRS operation (2) 114
Table E4 Water quality changes by MF in SWRS operation (3) 115
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min
operation with laundry water (RO scaling) 117
Table F2 SWRS data on the tap water after RO scaling 118
XVI
ACKNOWLEDGEMENTS
I am deeply indebted to my advisor Prof Brian A Dempsey who gave me the
opportunity to pursue higher learning and provided the continual support time advice
and guidance throughout this project and study at Penn State
I would like to thank Dr Hyunchul Kim who led me to the area of science and research
hand by hand for his generous support and guidance
I would also like to thank the committee member Prof Rachel A Brennan for her
suggestions from one of the best courses I have ever taken and Prof Fred S Cannon for
his valuable hints and the time on reviewing this thesis
The following peopleorganizations are also acknowledged and thanked for performing
specific analyses and supports Harry Su for providing the Energy-dispersive X-ray
spectroscopy (EDS) tests Bangzhi Liu (Material Research Institute) for coaching in the
use of the Field Emission Scanning Electron Microscope (FESEM) Missy Hazen for
supports in the use of Transmission electron microscopy (TEM) Henry Gong for
conducting the analysis of Inductively Coupled Plasma (ICP) and Albert Matyasovsky
for his encouragement and support
My family members and friends are deeply thanked for their encouragement and
continual support throughout my study
XVII
DEDICATION
This thesis is dedicated to my mother Qingping Ma for her support encouragement
and constant love that sustained me throughout my life
XVIII
ABBREVIATIONS
BOD Biological oxygen demand
CN Charge neutralization
Coag Coagulation
COD Chemical oxygen demand
DI De-ionized
EC Electrocoagulation
EDS Energy dispersive spectroscopy
Epi-DMA Epichlorohydrin dimethylamine
ETS Expeditionary tricon system
FESEM Field emission scanning electron microscope
GPM Gallon per minute
ICP Inductively coupled plasma
LMH L m-2h-1
MF Micro-filtration
MFI Micro-flow imaging
MW Molecular weight
NOM natural organic matter
OD Over-dosing
PA Polyamide
PACl Polyaluminum chloride
PDADMAC Poly-diallyldimethylammonium chloride
PP Polypropylene
XIX
PPM Part per million
PSD Particle size distribution
PVA Polyvinyl alcohol derivative
PVDF Polyvinylidene fluoride
RO Reverse osmosis
Sed Sedimentation
SEM Scanning electron microscope
SWRS Shower wastewater reuse system
TMP Trans-membrane pressure
TP Total phosphorus
TSS Total suspended solids
TEM Transmission electron microscopy
UD Under-dosing
UF Ultrafiltration
VFD Variable frequency drive
ZP Zeta potential
1
CHAPTER 1 INTRODUCTION
11 Project background
The increasing demand for usable water has focused attention on alternative sources
of water as well as water recycling and water re-use concepts Grey water which
contains water captured from sinks baths showers and laundries has traditionally been
considered a potential water source for re-use In industrialized countries approximately
150 liters of water are consumed per person per day and 60-70 of this water becomes
grey water (SHOMERA 2008)
Water is regarded as the second biggest logistic issue for military bases second only
to fuel Therefore conservation and reuse of grey water are important This is especially
true for military forward operating bases (FOBs) in Iraq and Afghanistan where water
supplies are limited and most bases do not have access to large water treatment facilities
Therefore an effective efficient reliable and flexible system for water recyclingreuse
system is particularly necessary to be investigated
Generally laundry effluents contain high levels of total suspended solids (TSS)
chemical oxygen demand (COD) total phosphorus (TP) and biological oxygen demand
(BOD) The pH of laundry waste water varies over a broad range from neutral to pH125
depending on what kind of detergent and other chemicals were used in the laundering
process (Sostrar-Turk et al2005) The most widely used methods for treatment of
laundry waste water are coagulation flotation precipitation adsorption and chemical
oxidation or a combination of these (Janpoor et al 2011) However the traditional
methods are insufficient for a small scale shower and laundry waste water treatment at
FOBs due to the inconstant water quality the need for simultaneous removal of TSS
surfactants and TP and especially the requirement for a small footprint and flexible
treatment unit that can be easily equipped and shipped
Besides conventional laundry wastewater treatment new technologies such as
membranes and electrocoagulation (EC) have been studied in recent years for the
2
treatment of laundry wastewater EC methods for laundry waste water treatment were
studied by several researchers ( Janpoor et al 2011 Can et al 2003 and Wang et al
2009) using aluminum plates Compared to conventional coagulants EC with aluminum
plates yielded better contaminant removal under some conditions However the product
water quality still failed to meet the minimum water quality guidelines for water re-use
In addition the effect of EC highly depends on the operating conditions so that the
application of EC will be challenging for laundries that have variable water quality and
high pH
In recent years membrane filtration has become widely used in wastewater
reclamation and recycling The study of potential water reuse by membrane filtration and
combined technologies has been conducted in areas of municipal wastewater effluent
(Wintgens et al 2005) municipal secondary effluents (Acero et al 2010) textile
effluents (Marcucci et al 2001) textile dyehouse wastewater (Soacutejka-Ledakowicz et al
1999) rural wastewater (Hyun et al 2009) and industrial wastewater (Sanchez et al
2010) Membrane filtration is an increasingly important technique for removal of
particulate suspensions in areas such as biotechnology water and wastewater treatment
and several industrial manufacturing processes For laundry wastewaters membrane
processes may have several advantages compared to conventional treatment including
better effluent quality reduced environmental impact of sludge reduced footprint
enhanced flexibility and increased tolerance of variable water quality (Baker 2004)
The main practical problems of membrane filtration are the reduction of permeate
flux with time or increase of transmembrane pressure (TMP) for constant permeate flux
caused by membrane fouling ie the accumulation of feed components in the pores and
on the membrane surface Membrane fouling involves specific interactions between the
membrane and adsorbed solutes and other solutes in the feed stream Fouling is
characterized by a time dependent decline in flux that can be irreversible in some cases
Thus fouling directly influences lifecycle costs for membrane treatment systems
Guilbaud et al (2010) used a direct nanofiltration (NF) process to treat grey waters
from washing machines in ships The results showed the tubular polyamide
3
nanofiltration membrane produced a quality of permeate that permitted recycling of 80
of the grey water when the NF was operated at 35 bar and 25 degC Pre-treatment was
needed to reduce the energy consumption and the cost Lee et al (2000) applied a pre-
treatment with the conventional coagulants polyaluminum chloride (PACl) and ferric
chloride (FeCl3) to test the flux enhancement in ultrafiltration (UF) and MF They
showed that the permeate flux was greatly enhanced by adding aluminum and ferric salts
whereas for the MF the flux decreased
Coagulation is a well-known traditional treatment with a long history in potable water
treatment industry The usage of coagulation as the pre-treatment step before other
technologies is also widely applied in all kinds of water treatment areas For most
wastewater the contaminants in the raw wastewater are negatively charged Similar
particles with negative surface charges repel each other and tend to remain stable without
adding a coagulant Al3+ and Fe3+ coagulant salts such as alum or ferric chloride can be
added resulting in destabilization and aggregation of particles in the waste water
Various organic polymers can also be added in order to coagulate including cationic
polymers that can also assist in neutralizing the negative charge on the contaminant
particles Charge neutralization (CN) means that just enough positively charged
coagulant has been added to neutralize the negatively charged contaminants Other
coagulation mechanisms may also be important including sweep floc and bridging For
MF treatment it is important to minimize the total mass and volume of added coagulant in
order to prevent excessive buildup of materials on the membrane CN by cationic
polymers has been used in potable water treatment in order to minimize production of
sludge
Most of the research dealing with laundry wastewater reuse by the combination of
coagulation and membrane filtration has been carried out in a lab or on a small pilot scale
(Hoinkis et al 2007) and no work has been reported on the use of cationic organic
polymers for the enhancement of MF and RO performance for laundry wastewater
4
12 Objectives
The objectives of this study were to investigate the application of coagulation plus
membrane filtration for the treatment of laundry wastewater for re-use Tests included
scales ranging from bench-scale lab experiments to full-scale operation In preliminary
studies it was discovered that very high doses of the conventional metallic coagulants
(eg alum and ferric chloride) were required due to the high pH of laundry water and the
generally high coagulant demand in laundry water High doses of conventional
coagulants resulted in membrane fouling during lab tests and it was anticipated that filed
application of metallic coagulants would result in severe logistic problems associated
with large volumes of chemicals and with disposal of sludge Consequently various
cationic polymers were investigated The effects of each polymer on contaminant
removal and on reducing membrane fouling were compared Furthermore the study was
also to provide a better understanding about the problems faced in full scale operation
and the fouling of RO which occurred during operation Since coagulation is usually
applied as the pre-treatment for membrane filtration this study can be also regarded as
guidance in coagulant selection and processing optimizing in all kinds of water treatment
facilities equipped with a membrane filtration section
The steps designed to achieve this aim were to
1 Broadly evaluate the zeta potential profiles in coagulation
2 Determine the removal rate of the contaminants in coagulationsedimentation
3 Investigate the membrane performance via specific resistance and compressibility
tests
4 Evaluate the performance at different pH and coagulant dosages
5 Determine the dosing regimes for the final selected polymer
6 Determine the critical flux of MF under each dosing regime
7 Compare the membrane performance in long-term operation of multi-cycles with
hydraulic cleaning for different dosing and flux conditions
5
8 Conduct full scale operation based on the optimized polymer dosage
9 Diagnose the effects of coagulant dosing during full scale operation
10 Develop hypotheses about successes and failures during full-scale operation and test
the hypotheses in the lab and
11 Investigate the physical and chemical characteristics of the RO fouling that was
observed during full-scale operations
13 Organization of the thesis
This thesis addresses several aspects of the polymer coagulation process in laundry
wastewater treatment and PVDF membrane performance in this hybrid filtration process
Laundry wastewater for these studies was obtained from a local commercial laundry
(CINTAS Inc) and from the Penn State laundry facility
The experimental materials and methods are contained in Chapter 2 The
experimental results are presented in the following three chapters
Chapter 3 is primarily related to the polymer selection and screening process In this
chapter 9 polymers supplied by the Nalco Company (Naperville Illinois United States)
were investigated in batch tests to evaluate the coagulation performance of laundry
wastewater Zeta potential (ZP) was measured as a function of coagulant dose The
selection criteria were low required coagulant dose and broad range of doses producing
ZP in the range -10 to +10 mV Based on the batch test results five polymers were
selected for further investigation of contaminant removal and membrane performance
Jar tests (20 min of mixing followed by 60 min of settling) were performed to evaluate
the polymer effects on ZP TSS COD TP turbidity and pH At the same time a dead-
end filtration system with PVDF membranes was used to measure specific resistance to
filtration and coefficient of cake compressibility After comparing the performances of
these five cationic polymers NALCOLYTE 8105 (a polymerized epichlorohydrin
dimethylamine Epi-DMA) was selected for further study as was effective over a broad
coagulant dose and at high pH Some of the work reported in this chapter especially
6
specific resistance to filtration and cake compressibility tests were done by Dr Kim and
that is acknowledged in the chapter
In Chapter 4 membrane filtration test results are reported that allowed identification
of critical flux values as a function of coagulant dose Especially three dosing regimes
(under-dosing charge neutralization and over-dosing) were studied using NALCOLYTE
8105 Subsequently multi-cycle constant permeate flux experiments were run in order to
investigate longer term effects of NALCOLYTE 8105 on operation and fouling of PVDF
MF membranes
Chapter 5 includes reports regarding the use of NALCOLYTE 8105 as a pre-
treatment to the membrane processes in the full-scale SWRS which was located adjacent
to the Penn State laundry facility In this part of the study it was discovered that RO
fouling was a serious problem That and other issues associated with full-scale
implementation of the treatment strategy are currently under further investigation
The conclusions and recommendations drawn from this work are in Chapter 6 and 7
respectively
7
CHAPTER 2 MATERIALS AND METHODS
21 Laundry wastewater description
Laundry wastewater samples were randomly collected from two locations One was
from a discharge pipe of a local industrial laundry ndash Cintas which is a private company
categorized under Uniform Rental Service in State College PA And the other one was
obtained from a sump inside of the Laundry Building of Penn State The sample was
collected during the laundry process Temperature and pH of raw water sample were
measured on site and the sample was stored at 4 ˚C prior to use Table 21 shows the
general characteristics of raw wastewater sample collected for this study
Table 21 General characteristics of the laundry wastewater in this study
Parameter Cintas Laundry (N=3)
Penn State Laundry Building (N=3)
pH 122plusmn05 1056plusmn02
Temperature (ordmC) 41plusmn10 38
ZP (mV) -61plusmn70 -296plusmn33
Conductivity (μS cm-1
) 1240plusmn267 2020
Turbidity (NTU) 735plusmn130 110plusmn56
COD (mg L-1) 1196plusmn72 414plusmn105
TP (mg PO43-L) 704plusmn8 729plusmn29
TP (mg TPL) 23plusmn4 235plusmn96
TSS (mg L-1
) 319plusmn90 168plusmn96
The temperature and turbidity of raw sample from Penn State Laundry Building were
measured once
8
22 Zeta potential (COD TSS Turbidity TP)
Zeta potential is the measurement of the net charge of the particles by determining the
electrophoretic mobility The development of a net charge at the particle surface affects
the distribution of ions in the surrounding interfacial areas resulting in an electrical
double layer around each particle The inner region which is called Stern layer contains
opposite charged ions that are strongly bound to the particle and move with it The ions
in the outer diffuse region are less firmly attached and any ions beyond the boundary
between the two layers do not travel with the particle The boundary is called the surface
of hydrodynamic shear or slipping plane and the zeta potential indicates the potential that
exists at this boundary (Malvern Instrument 2003)
The technique measures the displacement of particles when subjected to an electrical
field in a polar medium The two technologies listed below were applied to measure the
zeta potential in this study
221 Zeta Sizer Nano series
Zeta Sizer (ZEN 3600 Malvern Instrument) was applied in most of the ZP
measurements including raw water batch tests jar tests and the determination of
coagulation regimes The electrophoresis experiment on the sample is obtained by
measuring the velocity of the particles using laser Doppler velocimetry The ZP can be
obtained by application of the Henry equation (Eq 1) Four measurements were taken
and the results were averaged
UE= [ ]( ) Eq (1)
Where = Zeta potential
UE
= Electrophoretic mobility
= Dielectric constant
= Viscosity
f = Henryrsquos function
9
222 Zeta Compact
The Zeta Compact supplied by CAD Instrumentation was used for the precise
measurement such as determining the ZP of the MF filtrate Three measurements were
taken and the results are averaged
22 DI water
The high purity DI water used in dilution and membrane filtration tests was generated
by Milli-Q (Millipore Gradient A10) The DOC and resistivity of this water were less
than 005 mg L-1and 182 MΩcm-1 respectively The DI water for all the other purposes
was obtained in the lab using a research-grade water system
23 pH and conductivity
The pH and conductivity were measured by a Hach Sension 156 pHconductivity
meter The instrument was calibrated with Hach pH and conductivity standards every
month
24 Total suspended solids
A glass fiber filter (01 microm Whatman GF) was used in TSS measurement The
weight of the original filter was measured by a digital balance before 30 ml of water
sample was filtered After the filter was completely dried in the drying oven overnight at
60 degC the weight was measured again The difference between the two measurements
was the TSS of the 30 ml sample
25 COD and Total phosphorus
The COD and TP were measured according to the standard methods in the Standard
Methods for Water and Wastewater Measurement (21st edition)
10
26 Turbidity
Turbidity was measured using a Hach 2100P turbidimeter which was calibrated using
Hach turbidity standards before use Samples were measured twice and the results were
averaged
27 SEM
The physical nature of the membrane surface and the foulant layer was examined by
field emission scanning electron microscope (FESEM) (Leo 1530) Samples were
completely dried before tests In order to increase the resolution of scanning electron
microscope (SEM) images some samples were pretreated by Au sputtering due to the
low electric conductivity of the membrane polymer Images were obtained under 05-10
kV at a magnification range of 300-12000x The SEM test was conducted with the
assistance of Dr Bangzhi Liu
28 TEM
The structure of RO membrane was viewed in the cross-sectional images which were
obtained by transmission electron microscopy (JEOL JEM 1200 EXII)
The samples were completely dried placed in the cryoultramicrotome at -120degC and
cut into 70 nm sections before Transmission electron microscopy (TEM) test These
sections were placed on 400 mesh copper grids and viewed in the microscope The TEM
was conducted with the assistance of Missy Hazen
29 Particle size distribution and particle images
The Micro-Flow Imaging (MFI) DPA4200 (Brightwell technologies Inc Canada)
was used to determine the particle size distribution (PSD) and to collect particle images
The procedures are listed below
11
1 Prior to each sample run particle-free fluid (DI water) was flushed through the
system to provide a clean baseline and to optimize the illumination
2 The samples and controls were allowed to stand for 10 min at atmospheric
pressure and room temperature in order to assist in removing any air bubbles
which might have formed after sample preparation Then the samples and
controls were gently inverted and swirled taking care not to introduce air bubbles
3 1ml of each sample and control was gently drawn up into the pipette tip (100-
1000microL sterile aerosol pipet tip VWR) and placed in the inlet port Stirring was
set to the lowest setting
4 Data for the first 02 ml was discarded in order to purge any fluid that had been
left in the fluid path
5 During the run successive frames were displayed in screen This provided visual
feedback on the nature of the particle population as well as visual confirmation of
the data obtained
6 For each test PSD particle images circularity and mean intensity were collected
7 After each test the system was flushed with DI water soaked in 2 detergent
solution overnight flushed with DI water and preserved with 5-6 mL of DI water
remaining in the syringe barrel to wet and protect the system
210 Polymeric coagulants
Polymers are water soluble long-chain organic molecules which are widely used as
coagulants coagulant aids or flocculants in water treatment industry The properties of
polymers are affected by specific functional groups within the small chemical unit which
makes up the polymer with a molecular weight (MW) ranging from 50000 to over
10000000 (Mangravite Intertech 2002) The positive or negative charge exhibited by
the polymer the formation of H-bonds and hydrophobic interactions or charge transfer
interactions are also determined by the functional groups and result in various
performances in coagulationflocculation process
12
The majority of the reported cationic polymers are covered by quaternary ammonium
containing structures (Jaeger et al 2010) Epichlorohydrin dimethylamine (Epi-DMA)
and poly (diallyldimethylammonium chloride) (PDADMAC) have been applied in water
treatment since late 1980s (Dentel 1991) and proven to be the best selected coagulants
for treating laundry discharges to enhance the downstream MF performance in this
Four packages of commercial polymers (Appendix A Table A3) were purchased
from Nalco Company and nine of them were independently introduced in the coagulation
process All polymers were diluted to 1 (vv) with DI water before use and the dosage
of the polymers in this study was expressed as part per million (PPM) micro-liter of
undiluted polymer per liter of solution The characteristics of polymers used in this study
are shown in Table 22
Table 22 The characteristics of polymers provided by manufacturers
Polymer Ionicity Charge density Molecular weight Composition Form
Ultimer 1460
Ultimer 7752
Core shell 71301
Core shell 71303
Core shell 71305
Cat-Floc 8102 Plus
Cat-Floc 8108 Plus
NALCOLYTE
8105
Nalco 2490
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Cationic
Amphoteric
50-80
50-80
50-80
20-50
1-30
Unknown
Prime
Prime
Prime
High
Very high
(gt20MM)
Very high
Very high
Low (lt50 K)
Medium (1-3
MM)
Low (lt50 K)
AcAmDADMAC
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
AcAmDMAEAMCQ
PolyDADMAC
PolyDADMAC
EpiDMA
AADMAEAMCQ
Liquid
Emulsion
Prime
Prime
Prime
Liquid
Prime
Prime
Prime
AcAm = acrylamide DADMAC = diallyldimethyl-ammonium chloride DMAEAMCQ = dimethylaminoethylacrylate
methyl chloride salt polyDADMAC = polydiallyldimethyl-ammonium chloride EpiDMA = epichlorohydrin and
dimethylamine (asymp polyquaternary amines) AA = acrylic acid
13
211 Membranes
2111 Membrane characteristics
Flat mesh-filters were obtained by cutting a 10 microm polypropylene (PP) bag filter
(Serfilco) into pieces for sample pre-filtration
A general characteristic of membranes concluded by Stephenson et al (2000) are
listed in Appendix A (Table A1) Hydrophobic symmetric Polyvinylidene fluoride
(PVDF) MF membrane (022 μm Millipore) was selected in this study PVDF is a
highly non-reactive and pure thermoplastic and the membrane has an excellent durability
chemical and temperature tolerance and biological resistance The general
characteristics are listed in Table 23
Table 23 Membrane properties used in this study
Manufacturer Millipore
Material Polyvinylidene fluoride (PVDF)
Type Flat sheet
pore size 022 μm
Effective filtration area (cm2) 113
Pure water permeability (at 20 degC 10 Psi)
(lm2 h) 2020a
Intrinsic membrane resistance Rm 119 times 1011 mminus1
Phobicity Hydrophobic
Protein Binding Capacity as Insulin (microgcm2) 262 a The pure water permeability was obtained with DI water using constant pressure
membrane filtration experiment described in Section 217
2112 Preparation of membrane
New membranes were soaked for 10 min in methyl alcohol to increase the
hydrophility then flushed and soaked overnight in DI water prior to filtration tests The
membrane pure water permeability was measured with Milli-Q water in the constant
pressure filtration test at 10 psi for 10 min
14
2113 Hydraulic cleaning of membranes
Hydraulic cleaning of the fouled membranes involves surface flushing and backwash
using Milli-Q The surface flushing was performed manually and the backwash was
conducted by 20 seconds filtration of pure water by a pressurized vessel (Model 720340
Advantec MFS Inc CA) at 10 psi regulated by nitrogen gas after flipping the membrane
upside down in the membrane module
2114 Flux recovery
After hydraulic cleaning pure water permeability was measured with Milli-Q water
by conducting a constant pressure MF test (Section 217) for 10 min to determine the
irreversible fouling indicated by flux recovery rate JWJ0 (JW the pure water flux after
hydraulic cleaning J0 the initial pure water flux of the membrane without fouling)
212 Batch tests for zeta potential titration
Laundry wastewater (1 L) was filtered with 10 μm PP mesh filters transferred to a
12 L glass beaker the pH was adjusted to desired conditions (pH 7 for neutralized
condition pH 11 for the other measurements) using diluted HCl and NaOH solutions and
a given volume of each polymer (started with a small dosage) was added into the beaker
with agitation corresponding to approximately 200 s-1 of velocity gradient (G-value) by a
magnetic stirrer (cylindrical 25mm x 8mm) Polymer was step dosed after each 7-min
agitation and 15 mL sample was collected at the end of every stirring stage to
measurement the ZP changes of the coagulated sample until the ZP showed positive
values The variation in pH and conductivity of the sample solution was also monitored
during ZP titration tests Nine commercial polymers were investigated under each pH
condition and five of them were selected for further experiments
15
213 Jar tests
A series of jar test runs were performed to compare the coagulants effect on the
removal of contaminants in terms of turbidity TSS COD and TP by
coagulationsedimentation Laundry wastewater was pre-filtered with 10 μm
polypropylene (PP-10) mesh filter and the pH of the filtrate was adjusted to desired
conditions using diluted HCl and NaOH solutions prior to jar test After the pretreatment
25 L water sample was equally transferred into five 600 mL glass beakers before the
addition of targeted polymer at the same time The mixing (220 s-1 as G-value) was
introduced by the Phipps amp Bird stirrer with conventional blades (Model 7790-400) for
20 min immediately after polymers were added and the suspended particles were then
allowed to settle for 1 hour At the end of the agitation 20 L of the mixture was collected
from each of the beakers and the ZP was measured using Zeta Sizer (ZEN 3600 Malvern
Instrument) Supernatant was collected at about 1 cm beneath the water surface to
determine the residual turbidity TSS COD pH and TP after settling
In some experiments the 600 mL glass beaker which contained laundry waste water
was individually located in a 24 L water bath beaker during jar tests to maintain the
temperature of suspension in the range of 40plusmn20 degC by replacing the water in the 24 L
beaker continuously In the other experiments the temperature of laundry waste water
was equivalent to the room temperature (asymp22 ordmC)
214 Specific resistance and cake compressibility
Specific resistance to filtration identifies the increase in hydraulic resistance as a
function of the incrementally increasing mass of filter cake This measurement has been
used by numerous investigators (Tiller 1990 Farizoglu et al 2006 Kim et al 2006) to
determine the effects of coagulant addition on filter performance or to identify
filterability of untreated or treated wastewater samples Experiments were conducted by
measuring permeate volume versus time with a constant TMP applied Additional tests
can be performed using a range of TMP conditions Data were manipulated as described
in the following equations The author of this thesis assisted in these measurements but
Dr Hyunchul Kim was in charge of these measurements
16
tV = [(μαC)(2A2ΔP)]V+(μRm)(AΔP) Eq (2)
α = ([slope]times2A2ΔP)(μC) Eq (3)
α = αoΔP n Eq (4)
where tV is the filtration time per the cumulative permeate volume (sec m-3) μ
the fluid viscosity calibrated by temperature (kg m-1 s-1) C the particle concentration of
sample suspension (kg m-3) A the effective membrane surface area (m2) ΔP the trans-
membrane pressure (TMP Pa) Rm the intrinsic membrane resistance (m-1) α the specific
resistance (m kg-1) and n is compressibility
The slope can be obtained by plotting the data as tV versus V and α is measured
from the slope assuming that other physical parameters are known from Eq (3)
Compressibility is then estimated from the slope in logarithmic plots between α and ΔP
from Eq (4) Specific resistance (α) values obtained in the equations typically represent
an average value of the compressed cake since most of the compress ion of cake occurs in
the first few minutes of operation (Lee et al 2005) Moreover the pressure drop ΔPm by
filter itself is not deducted from total pressure drop (ΔP) caused by both cake and filter
To overcome these limitations in use of the classic equation an alternate method
was used in this study for highly compressible cakes In both dead-end and cross-flow
operation the permeate flux (J) is given by
J = ΔP[(Rm+Rc)μ] Eq (5)
where the total pressure drop (ΔP) is attributed to both the filter (ΔPm) and the
cake (ΔPc) Rc is the cake resistance (m-1) which is related to the cake load (m) and the
specific cake resistance (αc) by
Rc = mtimesαc Eq (6)
where m equals to the cake mass (CV kg) divided by effective filtration area (A
m-2) In dead-end operation m and Rc grow with filtration time which results in
decrease of permeate flux at constant ΔP or increase of ΔP at constant flux In dead-end
17
filtration the cake resistance tends to dominate so that the filtration cycle depends on the
specific resistance of cake formed onto the surface of filter (Lee et al 2005) The
cumulative permeate volume (V measurable in real time) and particle concentration
retained onto filter (C representable as difference in total suspended solid concentration
between feed and permeate samples) can be used Therefore equations (5) and (6) can
be expressed in terms of Rc and αc respectively as follows
Rc = ΔP(μJ) ndash Rm Eq (7)
αc = A(CV) times [ΔP(μJ) ndash Rm] Eq (8)
These equations were used to determine time-varying specific cake resistance in
this study Intrinsic filter resistance (Rm) was measured using particle-free solution (eg
deionized water) to determine specific cake resistance using Eq (8) Cake resistance (Rc)
is to be zero for particle- free solution and Rm can be obtained by examining the trans-
filter pressure (ΔPm) as a function of permeate pure-water flux (J) In general Rm has
been obtained by determining the total pressure drop (ΔP) at the initial water flux (Jo) on
the assumption that cake resistance (Rc) is to be zero when filtration begins and no cake is
deposited on the filter surface (Lee et al 2005 Farizoglu and Keskinler 2006)
The pressure drop across cake (ΔPc) can be also calculated by subtracting the
pressure drop caused by the intrinsic filter resistance (Rm) from total pressure drop (ie
ΔPc = ΔP ndash ΔPm) thus Eq (4) can be modified as follows
αc = αoΔPcn Eq (9)
where αo is an empirical constant that represents specific cake resistance in the
absence of applied pressure Cake compressibility (n) can be obtained by examining the
specific cake resistance (αc m kg-1) as a function of trans-cake pressure (ΔPc Pa) and it
varies between zero for an incompressible layer to greater than a value of one for very
highly compressible layer
Determination of specific cake resistance and cake compressibility consists of two
steps ie (step-I) formation of cake layer by passing a given volume of sample solution
18
includes particles or flocs through a filter or membrane under low trans-cake pressure and
(step-II) compression of cake mass by step-wisely elevating feed pressure The filtration
experiment is conceptually divided into two groups but no suspension occurs in the
filtration of the sample solution between step-I and step-II Using the derived equations
and continuous filtration method it is possible to not only present the variation in
hydraulic resistance from cake itself as a function of trans-cake pressure but also
calibrate resistance to filtration due to additional accumulation o f particles or flocs while
the cake is being compressed by filtering the sample solution
215 Critical flux determination
2151 Sample pretreatment
Critical flux determination tests were conducted with dead-end microfiltration system
as reported (Choi and Dempsey 2004) after sample pretreatment which includes pH and
temperature adjustment and sample pre-filtration by 10 microm PP filter Then targeted dose
of diluted polymer was added into 2 L pretreated wastewater sample which was located
in a 25 L-volume beaker prior to mixing The polymer dosage was determined from the
previous results in jar tests Mixing for coagulation was provided by a laboratory stirrer
(RW20 digital IKA) at 240 rpm for 10 min and by a magnetic stirrer (oval 32mm x
16mm) at minimum rate to prevent the sample from settling during the filtration process
A water bath was applied in some tests to keep the temperature of sample at
40plusmn20 degC by continuously replacing the water left in the water bath with fresh warm tap
water
19
2152 Microfiltration process
A schematic diagram of the experimental setup is shown in Figure 21 After
pretreatment the coagulated laundry discharges were connected to the membrane module
(47 mm In-Line Polycarbonate Filter Holder Pall Corporation) driven by a peristaltic
pump (6~600 rpm Cole-Parmer Instrument Co) which operated at a constant flow rate
of 00147 gpm by a solid state speed controller (Master Flex Cole-Parmer Instrument
Co) The feed pressure was controlled to remain around 10 psi by adjusting a pressure
control valve at the retentate line from where one part of water was diverted back to the
feed tank The critical flux was achieved by stepwise increasing the permeate flux which
was controlled by another peristaltic pump until prominent membrane fouling occurred
in terms of TMP rise in this case The permeate flux was set at a small value at the first
stage and remained constant for 10 min then increased slightly (varied form 25 L m-2 h-1
to 100 L m-2 h-1 depending on membrane performance and water quality) to the next 10
min stage TMP was recorded every seconds by two pressure meters (VWR Traceable
pressure gauge) at the feed and permeate lines and the permeate flux was obtained with
equation 10 by continuously recording the permeate volume using a digital electronic
balance (Ohaus Navigator balance accuracy plusmn 01g) The TMP and permeate flux were
averaged in each stage
J = ∆V(A∆t) Eq (10)
Where J = permeate flux (L m-2 h-1)
∆V = volume of permeate (L)
A = effective filtration area of membrane (m-2)
∆t = time (h)
The experiment was stopped after the TMP of 15 psi was reached An example of the
data processing for the critical flux determination is shown in Appendix B
20
Figure 21 Schematic diagram of critical flux determination setup
216 Multi-cycle filtration test
2161 Sample preparation
Laundry wastewater samples in the multi-cycle MF tests were pretreated using the
same procedures as described in section 2161 However some tests that were operating
at high permeate flux required another 2 L feed water to fill the feed tank when the water
level was running low
2162 Microfiltration process
A schematic diagram of the multi-cycle microfiltration experimental setup is shown
in Figure 22 8-10 cycles of MF tests were applied for each multi-cycle experiment to
investigate the performance of 022 microm flat sheet PVDF micro-filter in the longer term
coagulationMF process After coagulation the sample was immediately connected to
the system and feed at 00147 gpm for 10 min with no permeate flux after both of the
pressure gauges reached and stabilized around 10 psi for system calibration Each cycle
21
contained a filtration (15 min) process followed by hydraulic cleaning which included
surface flush and backwash (Section 2111) Permeate flux was controlled by a
peristaltic pump and was maintained constantly for membrane filtration During filtration
the pressure in both of the pressure gauges should stay in a reasonable range
(approximately 8~12 psi) and not exceed the limit (20 psi) by adjusting the pressure
control valve in the retentate line The MF experiment was stopped when the TMP was
higher than 20 psi The data was recorded the same way as described in section 2152
An example of the data processing is shown in Appendix C
Figure 22 Experimental set-up for a hybrid coagulationcross-flow membrane filtration
test (By Dr Hyunchul Kim)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
1 Feed tank
2 Feed pump
3 Dampener
4 Membrane module
5 Pressure control valve
6 Digital pressure gauge
7 Permeate pump
8 Digital balance
9 Pressure vessel for backwash
10 Nitrogen gas cylinder
11 Precision pressure regulator
Discharge
DIWDIW
1 2 3 4
56
6
7 8
9 10
11
Polymer
(1 Nalcolyte 8105)
22
217 Dead end microfiltration test
A schematic diagram of the dead-end MF experimental setup is shown in Figure 23
The membrane module was connected to the pressurized vessel (Model 720340
Advantec MFS Inc CA) and operated at a targeted feed pressure regulated by nitrogen
gas The pure water flux experiments were conducted with DI water at a constant
pressure of 10 psi A magnetic stirrer (oval 32mm x 16mm) was applied in coagulated
water sample at a minimum rate to prevent the sample from settling during filtration tests
The permeate flux was determined using a digital electronic balance (Ohaus Navigator
balance accuracy plusmn 01g) and calculated by equation 10 (section 2152) All
experiments were conducted at room temperature (asymp22 degC)
Figure 23 Schematic diagram of dead-end microfiltration experimental setup
23
CHAPTER 3 IMPACT OF POLYMERS ON
COAGULATION OF LAUNDRY WASTEWATER
The aim of this chapter was to provide an insight to the coagulation process of
laundry wastewater and to select the best polymers and the optimum polymer dosing for
coagulation Trends of zeta potential and removal of contaminants (COD turbidity TP
and TSS) by sedimentation were investigated for several cationic polymers at different
pH conditions In addition the specific resistances to filtration and the coefficients of
cake compressibility were investigated
Dr Hyunchul Kim was primarily responsible for the specific resistance and cake
compressibility work that is described in section 33 Those data are included in this
chapter because I was involved in these experiments (and will be a co-author on the
manuscript) and because those data are important for providing a comprehensive logic
about the process that was used to identify the best polymer and the optimized
operational conditions for treatment of laundry wastewater
24
31 Batch tests
Batch titration tests (Section 212) were conducted to identify the ability of different
polymers to neutralize the anionic charge on the particulate and dissolved materials in
laundry wastewater The ZP of raw laundry waste water was highly negative In the
coagulation process cationic polymer was added to reduce the particle negative surface
charge destabilize the suspension create agglomeration and form highly porous loosely
bonded aggregate (floc) (Kim et al 2001) Previous research shows the performance of
precipitation and membrane filtration is favored when the zeta potential after coagulation
is in the range of -10mV to +3mV (Sharp et al 2006) The surface charge on the solid
particle also depends on the pH in the solution (Stumm 1992) As the pH increases the
surface charge becomes increasing negative Therefore the goal in this part of the
experimental work was to find coagulants for which the required dose was low and that
would be effective over a broad range of doses Therefore we wanted to find polymers
that could bring ZP to gt-10 mV with a low coagulant dose and maintain ZP within the
range -10 to +3 mV over a broad range of coagulant doses
Since laundry wastewater usually is alkaline the ZP was determined as a function of
coagulant dose at both high and neutralized pH conditions Nine cationic polymers were
selected from four categories (packages) of commercial polymeric coagulant (Table A3
in Appendix A) in this test The selections were made based on recommendations by
technical personnel and from the polymer manufacturer
25
Figure 31 Effect of polymer dose on zeta potential at (top) pH 72 and (bottom) pH 108
Results from the batch tests are shown in Figure 31 In general ZP increased rapidly
with the lowest coagulant doses and the ZP stabilized near 0 mV for some of the
coagulants More chemical dosage was needed for high pH than for the pH neutralized
condition and some polymers (ULTIMER 1460 CORE SHELL 71303) failed to fully
neutralize the wastewater with moderate coagulant doses The failure to completely
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Zeta
po
ten
tial (m
V)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 72plusmn01
-80
-60
-40
-20
0
20
0 100 200 300 400 500 600 700 800
Polymer dose (microL L-1
)
Ze
ta p
ote
nti
al
(mV
)
ULTIMER 1460
ULTIMER 7752
CORE SHELL 71301
CORE SHELL 71303
CORE SHELL 71305
CAT-FLOC 8102 PLUS
CAT-FLOC 8108 PLUS
NALCOLYTE 8105
NALCO 2490
pH 108plusmn03
26
neutralize could indicate that the cationic functional groups of some of the polymers were
weakly basic and that the cationic charge on the polymer might be lower at pH 108
In addition to the ability to neutralize negative charge on the contaminants the
following aspects should be taken into account in polymer selection
1 It should be easy to prepare diluted solutions
2 The concentrated and diluted solutions should be stable over a range of
temperatures and easy to apply in the desired dosage
3 The best polymer should result in low absolute ZP values over a broad range
of coagulant doses
4 Application of the polymer should result in reduced concentrations of
contaminants after sedimentation or membrane filtration
5 The polymer should be effective at low doses compared to conventional
coagulants
6 The coagulant should be relatively inexpensive
7 Application should result in reduced fouling and in improved long-term
operation in MF
8 The polymer should be effective for both neutral and high pH conditions
Ultimer 1460 Core shell 71301 Cat-Floc 8108 NALCOLYTE 8105 and Nalco
2490 seemed to satisfied many of the selection criteria (further evaluation of some of
these criteria is reported later in this thesis) and were selected for further testing
32 Jar tests
Zeta potential and contaminant removal profiles for the five selected coagulants were
obtained from coagulation-precipitation experiments Results from these batch tests are
shown in Figure 32 Generally the highest contaminant removals occurred at the CN
27
condition but removals were good for coagulant doses close to the CN dose Most of the
polymers achieved 90 removal of turbidity and TSS and 60 removal of COD after
precipitation at both pH conditions However jar test results showed that coagulation-
sedimentation of laundry wastewater with cationic polymers resulted in poor P removal
(less than 30 ) Similar results were also found by some other researchers Trejo-
Gaytan et al (2006) suggested that the poor P removal might be due to a lack of a
subsequent low-intensity mixing flocculation phase It should be noted that use of
cationic polymers in potable water treatment also often results in poor removal of anionic
contaminants especially natural organic matter (NOM)
The results showed that 160 microLL dosage of Ultimer 1460L was sufficient to achieve
a high removal of contaminants (90 of turbidity 78 of TSS 60 of COD) (Figure
32 a) The contaminant removals declined to approximately 40 of turbidity 12 of
TSS and 47 of COD when the dosage of Ultimer 1460 was increased to 291 microLL
which was an OD condition for which the ZP was +8mv ie the particles were re-
stabilized due to too charge reversal Similar results were found for the other polymers
The data regarding water quality changes as a function of coagulant doses are provided in
Table A4-13
28
Figure 32 Coagulation-sedimentation of lint wastewaters (22ordmC) with two different pH
conditions (pH 72 on the left side) and (pH 11 on the right side) using five polymers
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Nalcolyte 8105 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Ultimer 1460 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Core shell 71301 dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
20
40
60
80
100
0 100 200 300 400 500
Cat-Floc 8108 plus dose (microL L-1
)
Res
idu
al
()
-80
-60
-40
-20
0
20
Ze
ta p
ote
nti
al
(mV
)
Turbidity TSS TCOD T-P Zeta potential
0
30
60
90
120
150
0 100 200 300 400 500
Nalco 2490 dose (microL L-1
)
Resid
ual (
)
-80
-60
-40
-20
0
20
Zeta
po
ten
tial
(mV
)
Turbidity TSS TCOD T-P Zeta potential
a)
b)
c)
d)
i)
j)
e)
f)
g)
h)
29
To further investigate the impacts of cationic polymeric coagulants on the
downstream MF membranes and to optimize the chemical usage for membrane filtration
the coagulant doses needed to achieve CN (dose to raise ZP around 0 mv) and lowest
effective UD (dose to raise ZP to -10 mV) based on the jar test results are shown in Table
31 Maximum contaminant removals were achieved at CN conditions In most cases the
polymer dosage for lowest effective UD was around half of the dosage of CN while still
yielding acceptable performance in contaminant removal
Table 31 Coagulant doses required for charge neutralization and lowest effective
underdosing (zeta potential raised to around -10 mV) at pH 7 and pH 11 for the five
polymers used in the jar tests
pH pH 7 pH 11
Dosing Condition CN (μLL) UD (μLL) CN (μLL) UD (μLL)
Ultimer 1460 196 60 234 79
Core shell 71301 119 60 119 60
Cat-Floc 8108 plus 291 138 291 99
NALCOLYTE 8105 157 40 157 79
Nalco 2490 157 40 157 79
33 Specific resistance to filtration and cake compressibility
The feasibility of using the five selected cationic polymeric coagulants for pre-
treatment prior to MF in laundry wastewater treatment was also evaluated in terms of
specific resistance to filtration and cake compressibility CN and minimum effective UD
dosage conditions for each polymeric coagulant at different pH values were described in
section 32
At pH 7 with cationic polymers addition a lower specific resistance to MF compared
to the raw sample was found for all the five tested polymers at CN condition (Figure 33
30
a) while specific resistance increased for the water after pre-filtration by PP-10 mesh
filter NALCOLYTE 8105 (Epi-DMA) showed the lowest specific resistance among the
five polymers for CN condition at both pH 7 and pH 11(Figure 33 a b) Interestingly
Cat-Floc 8108 plus (PDADMAC) resulted in a nearly horizontal line (slope=01) in the
plot of specific resistance vs applied pressure (Figure 33 a) which means the cake
compression (represented by the slope) on the membrane was negligible as feed pressure
increased At pH 11 NALCOLYTE 8105 and Cat-Floc 8108 plus also showed a
prominent effect in decreasing specific resistance at CN condition because of their
function group were both quaternary amine
Cat-Floc 8108 plus and Ultimer 1460 were the only two polymers that decreased the
specific resistance for the UD condition at pH 7 (Figure 33 c) With Core Shell 71301
(high MW long-chain polymer) dosed in the pretreatment an increase of specific
resistance was found in Figure 33 (b) (c) and (d) which might due to the formation of
long-chain highly adhesive floc with both hydrophilic and hydrophobic functional
groups that could easily adsorb to the PVDF membrane
A substantial decrease in specific resistance was achieved only by NALCOLYTE
8105 for UN condition at pH 11 (Figure 33 d) which was a promising result since
minimum dosage and high pH was the ideal condition for application Combined with its
favorable effect listed about at pH 7 NALCOLYTE 8105 was selected as the best
polymer for further treatment
31
(a) charge-neutralizing condition at pH 7
(b) charge-neutralizing condition at pH 11
y = 06x + 123
y = 07x + 114
y = 06x + 105
y = 06x + 110
y = 01x + 131
y = 09x + 88
y = 10x + 89
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (196 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
y = 07x + 116
y = 07x + 112
y = 05x + 129
y = 08x + 111
y = 05x + 113 y = 09x + 87
y = 05x + 122
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (234 microLL)
Core shell 71301 (119 microLL)
Cat-Floc 8108 plus (291 microLL)
Nalcolyte 8105 (157 microLL)
Nalco 2490 (157 microLL)
32
(c) under-dosing condition at pH 7
(d) under-dosing condition at pH 11
Figure 33 Specific resistance to filtration and cake compressibility (shown as slope) during the
membrane (022 microm PVDF) filtration of raw and coagulated lint wastewaters (22ordmC) Two
different coagulation regimes for each polymer were employed ie charge-neutralizing (ZP
between plusmn5 mV and highest turbidity removal) and underdosing (more negative ZP value and
relatively poorer contaminant removal) conditions
y = 06x + 123
y = 07x + 114
y = 08x + 105
y = 06x + 127
y = 08x + 101
y = 08x + 110
y = 08x + 112
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Lint wastewater prefiltered w PP-10
Ultimer 1460 (60 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (138 microLL)
Nalcolyte 8105 (40 microLL)
Nalco 2490 (40 microLL)
y = 07x + 116
y = 07x + 112
y = 07x + 117
y = 08x + 117
y = 08x + 105
y = 07x + 96
125
135
145
155
165
38 43 48 53 58
log (ΔPc) [Pa N m-2
]
log
(s
pe
cif
ic r
es
ista
nc
e α
c)
[m
kg
-1] Raw lint wastewater
Raw lint wastewater (pH 7)
Ultimer 1460 (79 microLL)
Core shell 71301 (60 microLL)
Cat-Floc 8108 plus (99 microLL)
Nalcolyte 8105 (79 microLL)
33
34 Summary
The addition of cationic polymers into laundry wastewater resulted in substantial
changes in ZP and in removal of contaminants after sedimentation Several of the
coagulants were effective for both neutral and high pH conditions Removal of over 80
of turbidity and TSS and over 60 removal of COD were achieved for both pH
conditions However the removal of TP was not as significant as the removal of COD
TSS and turbidity
NALCOLYTE 8105 (Epi-DMA) was judged to be the most effective of the tested
polymers for neutralization of the negative charges on contaminants in laundry
wastewater based on a rapid increase in ZP for low coagulant doses and maintenance of
ZP that was good for destabilization of contaminant particles over a broad range of
coagulant doses
Additional experiments were conducted in collaboration with Dr Hyunchul Kim that
showed that NALCOLYTE 8105 also was the most effective polymeric coagulant for
reducing specific resistance to filtration and for reducing cake compressibility At pH 11
the specific resistance using a PVDF MF membrane (022 μm) with Epi-DMA addition
was one order of magnitude less than the resistance obtained by other polymers for both
CN and UD conditions NALCOLYTE 8105 also resulted in the lowest specific
resistance to filtration at pH 7 Since the pH of the commercial laundry wastewater from
Cintas was around 12 and the UD condition was favored for chemical saving
consideration the NALCOLYTE 8105 coagulant was selected for further testing
34
CHAPTER 4 IN-LINE COAGULATION AND MF
CRITICAL FLUX AND LONG-TERM MF OPERATION
In Chapter 3 it was shown that the Epi-DMA coagulant NALCOLYTE 8105 was
effective for removal of contaminants and for reducing specific resistance to filtration and
cake compressibility during MF treatment of laundry wastewater In particular the
specific resistance for the UD condition at pH 11 was one order of magnitude less than
the other polymers This result was significant because it indicated that UD with
NALCOLYTE 8105 at high pH could result in effective treatment without pH adjustment
and at a dose that would not require large storage capacity for the coagulant and that
would be unlikely to result in residual cationic polymer in the MF discharge
The following experimental issues are dealt with in this chapter First the coagulant
dosing conditions to achieve UD CN and OD were re-defined by conducting the
coagulationprecipitation tests with fresh wastewater samples from the Cintas facility
Then the effect of NALCOLYTE 8105 on increasing the critical flux was studied over a
broad range of dosing conditions where critical flux was defined as the maximum
permeate flux that can be maintained without causing excessive membrane fouling and
exponentially increasing TMP It will be shown that Epi-DMA additions increased the
critical flux from 50 L m-2 hr-1 (raw sample) to 510 L m-2 hr-1 (CN) when evaluated using
sequentially increasing permeate flux driving force with PVDF MF with 10 min cycles
for each flux Finally the longer-term performance of the coagulantMF system was
evaluated using multi-cycle bench-scale MF experiments in which permeate flux was
held constant and a hydraulic cleaning operation was initiated after every 15 min
filtration cycle (commercial MF systems typically initiate hydraulic backwashes every 15
to 60 min)
35
41 Jar tests identifying dosing regimes
Fresh laundry wastewater was collected from Cintas during laundry processing and
stored at 4 ˚C prior to use After pH and temperature adjustment 25 L of this laundry
wastewater was equally transferred into five 600ml-glass beakers Jar tests were
conducted as described in section 26 to observe the trend of ZP and contaminant
removals (turbidity TSS COD and TP after sedimentation) with coagulant dosage
(Figure 41) In order to duplicate typical conditions for laundry wastewater the pH was
adjusted to 11 and the temperature was pre-heated to 40 ˚C and ept constant by water
bath during the tests
Figure 41 Coagulation-sedimentation of laundry waste water (40ordmC) using NALCOLYTE 8105
as the coagulant at pH 11
Once mixing stopped 20 mL of coagulated water were collected for ZP measurement
by Zeta Sizer (ZEN 3600) It showed that the ZP rose from -643 mV of raw water
sample to -48 mV with 118 microL L-1coagulant addition and then the ZP smoothly
-80
-60
-40
-20
0
20
40
0
20
40
60
80
100
120
140
0 200 400 600 800
Ze
ta p
ote
nti
al (m
V)
Re
sid
ua
l (
)
Polymer dose (microL L-1)
Turbidity TSS TCOD T-P Zeta potential
36
increased to +111 mv for a coagulant concentration of 566 microL L-1 The mixture was
allowed to settle for one hour and the supernatant was taken for turbidity TSS COD
and TP measurement Compared to the raw sample the turbidity and TSS increased
slightly at the polymer dosage of 40 microL L-1 where the ZP was -339 mv Effective
coagulation occurred at the polymer concentration of 118 microL L-1 and this dosage was
selected as the UD regime where removal rate of turbidity TSS and COD were 86
74 and 60 respectively The highest contaminant removals (96 of turbidity 77
of TSS and 63 of COD) were obtained for the CN condition when the polymer dosage
was 196 microL L-1 The over-dosing (OD) condition was at 385 microL L-1 (ZP of 71 mV) The
contaminant removals for the OD condition were decreased to 90 of turbidity 85 of
COD and 46 of TP due to particle restabilization These observations were consistent
with the earlier jar test results that were described in Figure 32 The data was presented
in Appendix A 14
42 Critical Fluxes for the dosing regimes
One of the major operational problems in MF is a decrease in permeate flux for
constant pressure operation or an increase in TMP for constant flux operation due to
membrane fouling The definition of critical flux has been widely discussed and studied
since the early 1990s Field et al first defined critical flux in 1995 as the highest
permeate flux in constant pressure operation for which there was no decrease in flux with
operating time Kwon and Vigneswaran mentioned in 1998 that the critical flux is the
highest permeate flux which no deposition of colloidal matter took place Both of those
definitions are based on theoretical concepts of particle deposition in which no deposition
occurs when back-transport exceeds transport towards the membrane Those concepts of
critical flux typically assume mono-disperse suspensions of particles and no change in
particle size (eg due to flocculation) over time
In these experiments critical flux is based on an operational definition and describes
the maximum permeate flux for which there is a continuing (same slope) increase in TMP
with increasing permeate flux These experiments are run using a peristaltic pump to
37
control the permeate flux (and another pump for recirculation of retentate) The
experimental methods are described in Section 216 Equation 3-5 was also used to
calculate the hydraulic resistances to filtration based on permeate flux TMP and the
solvent viscosity
Figure 42 shows the results of the critical flux determinations The results showed
negligible increases in TMP at sub-critical flux (permeate flux less than the critical flux)
and serious TMP increases at super-critical flux (permeate flux values greater than the
critical flux) The critical flux values for the three dosing conditions were approximately
300 L m-2 hr-1 (OD) 450 L m-2 hr-1 (CN) 180 L m-2 hr-1 (UD) and 50 L m-2 hr-1 (raw
sample) These short-term experiments indicated that the CN coagulation condition might
allow operation at approximately seven times higher permeate flux than in the absence of
coagulant without causing serious fouling The engineering significance is that operation
at higher permeate flux would allow more water production from a smaller-footprint MF
facility and therefore the capital costs for treatment would be less and the logistic
problems of transporting a laundry wastewater treatment unit to a remote location would
be decreased
38
Figure 42 Dead-end microfiltration of laundry wastewater for critical flux determination after
various pre-treatment by coagulation with NALCOLYTE 8105 at pH 11 and constant temperature
of 40 ˚C Permeate flux was constant for 10 min and increased stepwise
0
5
10
15
20
0 50 100 150 200 250 300 350
Me
an T
MP
(p
si)
Over-dosing Condition
0
5
10
15
20
0 100 200 300 400 500
Me
an T
MP
(p
si)
Charge Neutrilization Condition
0
5
10
15
20
0 50 100 150 200 250
Me
an T
MP
(p
si)
UD Condition
0
5
10
15
20
0 20 40 60 80 100
Me
an T
MP
(p
si)
Mean permeate flux (L m-2 hr-1)
Zero-dosing Condition
39
43 Multi-cycle constant flux MF experiments
Multi-cycle membrane filtration tests were employed to quantify the changes in TMP
at constant permeate flux and when a backwash was operated every 15 min The
procedures for sample pre-treatment membrane filtration membrane flush and backwash
and the methods for data collection were described in Chapter 2 The multi-cycle MF
results for CN UD OD and zero-dosing conditions are shown in Figure 53 Figure 54
Figure 55 and Figure 56 respectively
For every dosing regime one or two sets of sub-critical permeate flux and one set of
slight super-critical permeate flux were selected for multi-cycle MF based on the critical
flux determination tests For CN condition (196 microL L-1) the initial TMP in multi-cycle
MF increased slightly from 045 psi at permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a))
057 psi at permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) to 074 psi at permeate flux
of 510 plusmn 20 L m-2h-1 (Figure 43 (c)) Similar results were found in the other dosing
regimes that the initial membrane resistant was proportionate to the flux
For the CN condition negligible TMP increases were found after the first two cycles
at the permeate flux of 200 plusmn 15 L m-2h-1 (Figure 43 (a)) indicating that no fouling was
formed on the membrane surface when the permeate flux was less than half of the critical
flux (asymp 450 L m-2h-1) At the permeate flux of 385 plusmn 8 L m-2h-1 (Figure 43 (b)) the
TMP increased in an increasing saw-tooth pattern with increasing cycles of operation
There was recovery with each hydraulic backwash but the TMP did not return to the
original baseline value The clean TMP increased from 057 psi at the beginning of the
experiments to 123 psi at the beginning of the last cycle which meant the fouling was
occurring that could not be removed by the hydraulic cleaning procedure even though
the permeate flux was still controlled to be sub-critical Chemical cleaning would be
required to further recover the membrane performance
40
Figure 43 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for charge neutralization condition at pH 11 and constant temperature
of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600
TM
P (
psi
)
Charge-neutralization condition Flux=200plusmn15 (L m-2h-1)
a)
0
1
2
3
0 200 400 600 800 1000 1200
TM
P (
psi
)
Charge-neutralization condition Flux=385plusmn8 (L m-2h-1)
b)
0
1
2
3
0 200 400 600 800 1000 1200 1400
TM
P (
psi
)
Specific permeate volumn (L m-2)
Charge-neutralization condition Flux=510plusmn20 (L m-2h-1)
c)
41
Similar results were found for the OD condition TMP increased slightly at a flux of
240plusmn10 L m-2h-1 (Figure 44 a) but exponential increases occurred within each 15-min
cycle and the post-cleaning TMP was higher at the beginning of each sequential cycle for
a permeate flux of 420plusmn15 L m-2h-1 (Figure 44 b) It was also observed that a cake layer
was produced with the OD condition and that most of the cake was removed with
backwashing
Figure 44 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for overdosing condition at pH 11 and constant temperature of 40 ˚C
0
1
2
3
0 100 200 300 400 500 600 700
TM
P (
psi
)
Over-dosing condition Flux=240plusmn10 (L m-2h-1)
a)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
TM
P (
psi
)
Specific permeate volumn (L m-2)
Over-dosing condition Flux=420plusmn15 (L m-2h-1)
b)
42
Figure 44 (a) shows that negligible membrane fouling occurred for the UD condition
at a sub-critical 100plusmn5 (L m-2h-1) The TMP difference between the beginning of the first
cycle and the end of the last cycle was 02 psi Using the permeate flux of 180plusmn8 L m-2h-
1 (Figure 44 b) which was near the critical flux for UD the TMP increased sharply after
the first cycle and the experiment had to be interrupted in the third cycle The hydraulic
cleaning was not as effective for the UD critical flux conditions as it was for the CN or
OD critical flux conditions
Figure 45 Transmembrane pressure to permeate volume in the PVDF microfiltration (022microm)
for ten cycles at various constant permeate flux of polymer pre-treated laundry lint wastewater
with NALCOLYTE 8105 for underdosing condition at pH 11 and constant temperature of 40 ˚C
The multi-cycle MF experiments on the raw wastewater at sub-critical around critical
and super-critical flux are shown in Figure 46 (a) Figure 46 (b) and Figure 46 (c)
respectively Negligible TMP increase was shown during the whole test at 25plusmn4 L m-2h-1
0
1
2
3
0 50 100 150 200 250 300
TM
P (
psi
)
UD condition Flux=100plusmn5(L m-2h-1)
a)
0
3
6
9
12
15
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
UD condition Flux=180plusmn8 (L m-2h-1)
Over range stop testing
b)
43
(Figure 46 (a)) When the permeate flux was around the critical flux (50plusmn3 L m-2h-1)
obvious membrane fouling occurred in each cycle However around 100 TMP
recovery was achieved by hydraulic backwashing (Figure 46 (b)) The TMP increase
after hydraulic cleaning at super-critical permeate flux for raw water was also negligible
compared to the sample with polymer addition
Figure 46 Transmembrane to permeate volume in the PVDF microfiltration (022microm) for multi-
cycles at various constant permeate flux for raw laundry wastewater at pH 11 and constant
temperature of 40 ˚C
0
1
2
3
0 10 20 30 40 50 60 70 80
TM
P (
psi
)
Zero-Dosing Condition Flux=25plusmn4 (L m-2h-1)
a)
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
psi
)
Zero-Dosing Condition Flux=50plusmn3 (L m-2h-1)
b)
0
4
8
12
16
20
0 20 40 60 80 100 120 140
TM
P (
psi
)
Specific permeate volumn (L m-2)
Zero-Dosing Condition Flux=75plusmn3 (L m-2h-1)
c)
44
44 Multi-cycle microfiltration tests at 50 L m-2h-1 for simulating the full-
scale operation
To investigate the impact by coagulation with NALCOLYTE 8105 on microfiltration
membrane under the simulation of SWRS four dosing conditions were used for the pre-
treatment of feed water to the multi-cycle MF model while the permeate flux were
maintained at 50 L m-2h-1 which was the suggested permeate flux for the MF in SWRS
New water samples were collected from Cintas and refrigerated at 4 ˚C prior to use in this
study
Figure 47 Transmembrane pressure to time in the PVDF microfiltration (022microm) for ten cycles
at 50 L m-2
h-1
of polymer pre-treated laundry lint wastewater with NALCOLYTE 8105 for zero-
dosing underdosing charge neutralization and overdosing conditions at pH 11and constant
temperature of 40 ˚C
0
1
2
3
0 20 40 60 80 100 120 140 160
TMP
(psi
)
Time (min)
Raw Sample 0 umL
UD 79umL
CN 196 microLL
OD 385 umL
45
The results of multi-cycle MF for various dosing conditions at 50 L m-2h-1 are
presented in Figure 47 The tests for UD and CN conditions developed the similar TMP
profile TMP increased from 004 psi to 016 psi in the first cycle then remained constant
till the end of experiments for ten filtration cycles TMP increase in each cycle was
shown for raw water and OD condition The hydraulic cleaning was excellent in TMP
recovery for raw water since the TMP at the beginning of each cycle was even lower than
the CN and UD conditions The irreversible fouling was building up as the positively
charged wastewater kept passing through the membrane The result of OD condition at
50 L m-2h-1 was contrary to the multi-cycle result for OD to a certain degree which was
probably due to the water quality changed in this experiment and the particle was more
re-stabilized in this condition
46
45 Contaminant removals in bench scale MF experiments
The contaminant removals by filtration through the PP-10 bag filter by coagulation
followed by sedimentation (coagsed) and by coagulation followed by MF (coagMF) are
compared in Figure 48 UD CN and OD conditions were evaluated for the treatments
that included coagulant addition
The PP-10 bag filter removed about 15 of TSS and negligible amounts of the other
contaminants Coagulation and sedimentation removed more than half of turbidity COD
(except for the OD coagsed treatment) and TSS Coagulation MF produced 100
removals of TSS and turbidity and slightly increased removals of COD (65plusmn45 )
compared to coagulation sedimentation None of the treatments removed more than 25
of TP In fact coagulationMF removed less TP than coagulationsedimentation
Figure 48 Contaminant removal () for different treatment methods (pre-filtration MF and the
suspension collected after coagulation and precipitation) and different dosing conditions on
Cintas laundry wastewater
0
20
40
60
80
100
Filtrate ofpp-10
Coagsed(UD)
Coagsed(CN)
Coagsed(OD)
CoagMF(UD)
CoagMF(CN)
CoagMF(OD)
Con
tam
inan
t re
mo
val (
)
Treating method
Turbidity
COD
T-P
TSS
47
45 Summary
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicate that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
The multi-cycle MF experiments using the UD and CN conditions showed almost no
membrane fouling at 50 L m-2 hr-1 which was the suggested permeate flux value for full-
scale operation with SWRS For the raw water membrane fouling was observed and
kept building up within each 15 min filtration cycle but a high TMP recovery (almost
100) occurred after flushing and backwashing with DI water Better removal of
turbidity TSS and COD were achieved using coagulationMF than had been observed
using coagulationsedimentation Neither procedure resulted in more than 25 removal
of TP
The experiments in this chapter were also designed to guide and simulate the
operation of SWRS at the bench-scale before moving to the full-scale tests described in
the next chapter The results in this chapter showed that pre-treatment with coagulant
addition was needed to decrease MF fouling and process higher permeate volumes The
chemical dosage should be controlled in the range from UD to slightly OD conditions
48
CHAPTER 5 FULL-SCALE EXPERIMENTS ON THE
SHOWER WASTEWATER REUSE SYSTEM
In Chapter 3 it was shown that NALCOLYTE 8105 was the most effective of the
tested has polymeric coagulants for removal of contaminants removal as well as
improving MF performance for laundry wastewater treatment at high pH Three dosing
regimes (UD CN and OD) of coagulation were also defined for studies on longer time
operation system
In Chapter 4 the critical flux in microfiltration of treated laundry wastewater in
different dosing regimes was determined first Those studies showed that pre-treatment
by NALCOLYTE 8105 (Epi-DMA) had a significant potential to increase the permeate
flux in MF without membrane fouling
To simulate the low pressure MF operation part in SWRS a multi-cycle
microfiltration with hydraulic cleaning mode was employed and the results were
described in Chapter 4 Those tests were designed to test the long-term MF performance
in different dosing and permeate flux conditions The results showed that the UD and CN
conditions could be effective and efficient for MF operation with negligible TMP
increases Those tests were performed using laundry wastewater from Cintas
The main aim of this chapter was to set up and test the operation of SWRS unit with
the discharge from Penn State Laundry Building The opportunity to use the SWRS
evolved late in the research when it became apparent that the Army was unable to
establish a populated base camp at which laundry wastewater was generated The Army
requested that we set up the full-scale SWRS near Penn State The earlier tests were
performed using wastewater from Cintas but permission was not granted to set up the
SWRS at Cintas Luckily we received permission to set up the SWRS adjacent to the
Penn State laundry facility Thus the full-scale SWRS was tested on a different
wastewater than was used for the earlier bench-scale tests Since earlier tests had shown
49
that there was a possibility of irreversible MF membrane fouling without the addition of
the Epi-DMA coagulant the strategy was adopted to run the first SWRS tests using tap
water from a nearby fire hydrant followed by coagulated laundry wastewater that had
been dosed with CN then UD conditions then OD conditions and finally no coagulant
It was anticipated that this sequence might allow more tests to be run before the MF
filters were fouled The TMP changes in MF were continuously recorded and the water
quality changes were also investigated
50
51 SWRS description
511 System overview
The Shower Water Reuse System (SWRS) is a fully self-contained water purification
system which is designed to recycle 75 of shower wastewater and recover up to 10000
gallons per day The SWRS is part of the Expeditionary Tricon System (ETS) where a
tricon is a unit that occupies a third of a flatbed load Tricon units are also available to
provide for laundry shower latrine and other required services needed at 150-man Force
Provider camps
One SWRS unit was shipped to state college PA in late October 2011 and set up at
the northeast side of the Penn State laundry building Figure 51 shows the SWRS tricon
and two 3000 gal (3K) storage bladders
Figure 51 SWRS setup outside of the Laundry Building in the Pennsylvania State University
Laundry wastewater inject
3K bladder 1
3K bladder 2
SWRS unit
Diverter box
Water discharge from SWRS
Water inlet
51
The inlet of unit was connected to each of the 3K bladders Laundry wastewater was
pumped from a sump inside the laundry building to the 3K bladders Epi-DMA polymer
was dosed directly into the bladders in a batch fashion In typical operation one 3K
bladder was feeding the SWRS while the other bladder was filled and dosed The
flowchart of SWRS under standard operation is shown in Figure 52 The sequence of
treatment was self-cleaning 15 microm steel mesh pre-filter MF RO granular activated
carbon (GAC) and ultraviolet (UV) disinfection Storage containers hold calcium
hypochlorite for disinfection at several points within the treatment and after treatment
and sodium bisulfate to generate reducing conditions within the RO unit sequence
Other components of the SWRS are also shown in Figure 52 The low-pressure
pump typically operates at between 105 and 12 gpm The recycle tank receives the water
from the MF filtrate and is the feed for the high-pressure pump for the RO The high
pressure pump draws water from the recycle tank at 30 gpm and feeds the three
sequential RO canisters arranged in series Most of the RO feed water is recirculated back
to the recycle tank or wasted producing only 80 gpm of RO filtrate which passes
through the GAC column UV disinfection and post chlorination in series Of the
remaining 22 gpm of concentrated water from RO 205 gpm flows back to the recycle
tank and 15 gpm is discharged to the waste tank
52
Figure 52 SWRS flowchart under standard operation
Figure 53 SWRS front site overview and the main treating components
MF filter RO vessels
UV light
GAC filter
Pre-filter
Recycle tank
53
512 Microfiltration characteristics
The MF (Figure A4 c) in the SWRS contains PVDF porous hollow-fibers with an
average pore size of 02 microm When filtering all of the wastewater passes from the
outside into a hollow core in each fiber According to the operator and field maintenance
manual a backwash is performed automatically every 15 min to remove the trapped dirt
and bacteria and to prevent the TMP from increasing which may result in MF fouling as
well as flux decline In operation we discovered that the unit automatically backwashed
every 60 min The filtered water flows to the recycle tank Backwashing includes a high
cross-flow on the outside of the hollow fibers to remove accumulated materials followed
by a pneumatic inside-out cleaning The low-pressure pump uses water from the recycle
tank for the backwash procedure
513 RO filter
The water pressurized (100 to 350 psi) from the high pressure pump passes through
three RO vessels (Figure D4 bd) in series from the top vessel to the middle vessel and
then to the bottom vessel A pressure control valve automatically adjusts the pressure
needed at the end of RO to drive 8 gpm of final reuse water through the RO membrane
The remaining 22 gpm passes through a pressure control valve to give the required RO
pressure to yield the 8 gpm reuse water flow Then 205 gpm of concentrated wastewater
flows back to the recycle tank and the flow of 15 gpm is discharged to the waste tank
514 Chemical injection system
Calcium Hypochlorite solution is injected at two locations One is injected into the
MF inlet for chlorine soak and the other one is injected into the reuse water to provide 2
to 5 mgL of free chlorine to prevent later biological activity in the finished water
Sodium bisulfite is injected into the discharge of MF to neutralized any chlorine
before the water enters the recycle tank since the active layer of the downstream RO
membrane will be harmed and lose their ability to reject salts and organic material during
long contact time with chlorine
54
515 Air system
The air system provides pressure of 128 to 142 psi to drive the pre-filter cleaning disc
and for backwashing of the MF during SWRS operation The air system consists of an air
compressor air drier air tank and various controls and instruments
516 GAC filter and UV light
Images of the GAC filter and the UV light are shown in Figure D4 (b) The product
water collected from the RO vessels passes through carbon filters which filter out any
taste and odor that may be present Downstream of the carbon filters the reuse water
passes through a high-intensity UV disinfection station
517 Microfiltration operating without high pressure pump set-up and
backwashing strategy
Operation of the SWRS for treatment of laundry water resulted in fouling of the RO
system This result might be expected due to the high hardness alkalinity and
temperature of laundry wastewater However our task was to evaluate the performance of
the MF components (the Army is evaluating reuse options for laundry water that do not
require RO such as laundry water reuse or flushing latrines) The SRWS is highly
automated and we had to develop a strategy for operation of the unit without using the
RO component In order to investigate the MF performance and prevent water passing
through the high-pressure section the operation and backwashing strategy was designed
and listed in Appendix F
52 SWRS setup and dosing strategy at Penn State Laundry Building
Figure 54 shows the flowchart and the dosing strategy of SWRS in treating the
laundry wastewater from the Laundry Building in the Pennsylvania State University The
wastewater was pumped to the two 3k bladders in turns through a sump pump installed at
the drainage sump where the laundry discharge was the only water source The inlet of
55
the sump pump was maintained approximately one foot below the water surface and two
feet from the bottom to prevent too many lint particles drawing into the pump which may
result in pump clogging Nonetheless there was a large accumulation of lint (from the
bottom of the sump) that accumulated on the sump pump intake Some of these lint
clumps passed into the bladders
After filling a 3K bag coagulant (Epi-DMA diluted to 1 (vv) before use)
sufficient to achieve the desired condition (UD CN OD) was added from the top of
bladder followed by 10 min of mixing (pushing and jumping on the bladder to achieve
internal mixing) After coagulation and mixing the filled bladder was fed to the SWRS
unit and the operation started At the same time the other empty bladder was charging
with laundry wastewater and was coagulated in the same manner The filling polymer
dosing and treatment procedures using the two 3K bladders were conducted in sequence
by switching connection between bladders and the sump pump (at the sump pump side)
and the tee (at the inlet of SWRS as shown in Figure 55) Other images for hose
connections and other physical setups are shown in Appendix D
Figure 54 SWRS set-up at Penn State Laundry Building
56
Figure 55 Hose connection a sequential way used in Penn State Laundry wastewater treatment
by SWRS The SWRS unit is on treatment with wastewater in Bladder 2 which has been
coagulated before and bladder 1 is filling with laundry wastewater at the same time
53 SWRS operation at various microfiltration permeate flux with clean
water
The performance of the different components in the SWRS was first tested with tap
water obtained from a fire hydrant nearby By adjusting the flow rate control valve at the
MF inlet the performance of the dead-end MF was studied at various flow rates The
system operation was maintained for at least 30 min under each flow rate from 53 gpm
to 121 gpm The TMP and the flow rate were manually observed and these values were
recorded for the MF component Data were also manually recorded for other SWRS
functions (TMP of RO TMP of pre-filter conductivity of feed and reuse water and the
Bladder 1
Bladder 2 SWRS unit
SWRS inlet
Tee
57
incomeoutput flow rate) The TMP for the MF component did not increase within each
30min-filtration period when using tap water as the feed The TMP increased linearly
with the flow within a realistic operating range of 6~12gpm (approximately 30 to 60 L m-
2 h-1 permeate flux) These results indicate that no MF fouling occurred when using tap
water and that the whole system was functioning well (Figure 56 and Appendix G)
Figure 56 Transmembrane pressure to flow rate for microfiltration of SWRS operation using
tap water
54 Results of long-term SWRS operation
In order to investigate the performance of the SWRS during long-term operation a 24
hour non-stop operation was conducted with tap water feed and with a relatively constant
MF flow of 112 gpm TMP values were recorded and the result is shown in Figure 57
The performance of MF during the treatment of laundry wastewater was also
investigated at a range of flows TMP data from several laundry wastewater experiments
that used UD CN and slight OD coagulant doses at relatively constant MF flow of 1055
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12 14
Tran
sme
mb
ran
e p
ress
ure
(psi
)
Flow (gpm)
58
gpm are shown in Figure 58 In most cases the TMP and permeate flux readings for the
first 10 min of operation after coagulation were excluded because there were frequently
flow upsets associated with accumulation of lint in the pre-filter during the first few
minutes The TMP results at constant permeate flux also showed that there was negligible
increase of TMP during long-term operation with coagulated laundry wastewater No
difference in MF was found for different dosing conditions The TMP data for both tap
water and for laundry wastewater long-term operation were also consistent with the TMP
versus flow data presented in Figure 56
Figure 57 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1120 gpm using tap water
Figure 58 Transmembrane pressure to time for microfiltration of SWRS at a constant permeate
flow rate of 1055 gpm using tap water
In addition to comparisons of tap water and laundry wastewater filtration at constant
permeate flux experiments were conducted at variable permeate fluxes for laundry
wastewater that received a range of coagulant doses from no coagulant to OD conditions
Data for no coagulant extreme UD conditions and UD conditions are shown in Figure
59 The data show scatter but the linear regressions of TMP versus permeate flux
indicated that the TMP data for uncoagulated to UD coagulated laundry wastewater were
consistent with TMP data for tap water This finding appeared to be different than the
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
3
5
7
0 5 10 15 20 25 30
TMP
(psi
)
Time (h)
59
previously-reported results obtained from the bench-scale lab work This apparently
different result will be discussed later in this chapter and is also the subject of on-going
research
Figure 59 Transmembrane pressure to flow rate for microfiltration of SWRS using laundry
wastewater when the flow rate declined due to the fouling on the mesh filter
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Tran
smem
bra
ne
pre
ssu
re (
psi
)
Flow Rate (gpm)
Raw sample 1222
Super underdosed 1215
underdosed sample 1216
Clean water baseline
Linear (Raw sample 1222)
Linear (Super underdosed 1215)
Linear (underdosed sample 1216)
60
55 Water quality changes
Figure 510 Contaminants residual and water quality changes during SWRS operation
Removals of contaminants during the treatment of laundry wastewater by SWRS are
shown in Figure 510 for an UD condition The MF resulted in 100 removal of
turbidity and 75 removal of COD These results were consistent with results from the
bench-scale coagulation and filtration experiments More TP was removed (55) using
the full-scale SWRS-MF than was observed with the bench-scale coagulation RO
reduced the COD from 25 of influent concentration in the MF filtrate to 2 of influent
concentration in the RO filtrate 100 removal of COD was achieved in the finished
water with the help of the downstream GAC and UV light which also slightly increased
removal of TP
109
36
0
20
40
60
80
100
120
AfterCoagulation
MF Feed MF Permeate Ro Filtrate FinishedWater
Con
tam
inan
ts r
esid
ual
()
Treating method
Turbidity
TCOD
T-P
61
56 SWRS operation problems
However several problems some caused by wastewater quality and chemical
addition and some caused by system errors were observed during SWRS operation
561 Pre-filter fouling
Fouling occurred on the pre-filter and occasionally resulted in flow rate decline at the
beginning of treatment (decline time 10~30min) when SWRS processed raw laundry
wastewater or super under-dosed laundry wastewater where effective coagulation had not
been introduced
Since the pre-filter with a cylindrical screen (15 microm) conducted a self-cleaning
process in which a disc travelling down the inside of the screen and scrapping the debris
from the screen every minute The flow rate normally recovered after the automatic
cleaning However there was one time when the flow rate did not recover from the self-
cleaning thus the pre-filter fouling accumulated and resulted in system shut-down At
that time the SWRS was processing water at the bottom of the bladder which apparently
contained sludge from the bottom or the laundry sump or previously coagulated lint
particles
562 RO scaling
RO scaling occurred at the first time when SWRS started to process laundry
wastewater The pressure flow rate and conductivity changes of pre-filter MF and RO
at normal operation during RO scaling and after RO scaling are listed in Appendix G
During RO fouling the TMP of RO increased from 110 psi to 287 psi after coagulated
laundry wastewater was treating for 30 min (Table G1) which resulted in flow rate
decline from 8 gpm (normal condition) to 58 gpm The declined flow rate in RO also
triggered the decrease of both flow rate and TMP in the pre-filter and MF which was
probably automatically adjusted by the system since the incoming flow rate did not
change by adjusting the flow rate control manual valve
62
The RO fouling did not recover by switching the water source from the laundry
wastewater back to the tap water (Table G2)
563 Other problems
Sometimes the ldquoTemporary shutdownrdquo process could not be completed since the
system would be stuck in the ldquo15min chlorine soa rdquo unless SWRS had to be shut down
manually
57 Hypotheses regarding differences between bench-scale
experiments and full-scale tests
Several hypotheses were developed to explain why the SWRS MF membrane was not
fouled as much compared to the bench-scale experiments The following are possible
reasons for this discrepancy
571 Water quality
The Laundry Building at the Pennsylvania State University is responsible for the
laundry business inside the university The raw water quality varied and the turbidity and
COD were 90 and 70 respectively (Table 21) less than the laundry wastewater
collected from Cintas which was used as the water source in the bench-scale tests
572 Pre-filter sequence
In the lab experiment the PP filter was applied prior to coagulation However the
polymer addition was in front of pre-filtration in SWRS which could remove the
particles that had been grown in the coagulation process before the water passed through
MF In addition the coagulated particles also might be the reason leading to pre-filter
fouling during SWRS operation
573 Cross-flow and backwash
63
SWRS operated in a larger scale and at a much higher flow rate (105 gpm) than the
lab experiments (2810-4 gpm) even though the permeate flux was the same The higher
flow rate could create a more intense turbulent cross-flow across the membrane surface
thus decreased membrane fouling in the filtration process
Compared to backwash in the lab work (section 2113) SWRS conducted a more
rigid backwash provided by compressed air at 128 to 142 psi and could have resulted in a
better membrane flux recovery
574 Coagulated lint particle in the settlement
The two 3K bladders were continuously running without a thorough cleaning during
all the tests A significant amount of lint particles and floc generated during coagulation
were settled and accumulated at the very bottom (less than 1 foot in height) of the bladder
The compressed lint particles that were trapped below the draining hole were found until
we started to clean and pack up after fulfilling the tests
The last few tests which were designed to treat laundry wastewater at UD or zero-
dosing conditions could have been influenced and may have resulted in a higher dosed
coagulated wastewater when contacting with the settled particles which contained some
of the remaining cationic polymers
58 Additional multi-cycle bench-scale microfiltration tests on Penn
State laundry wastewater
To investigate the influence on MF by water quality (section 551) and pre-filtration
(section 552) the multi-cycle (8 cycles) tests were conducted on Penn State laundry
wastewater as described in section 2162 The water sample was prepared the same way
as the multi-cycle tests on Cintas laundry wastewater except that pre-filtration was
applied after coagulation The permeate flux was maintained at 50 L m-2h-1 which was
consistent with the flux in SWRS The results are shown in Figure 511
64
Figure 511 Multi-cycle test on Penn State laundry water with pre-filtration by 10 μm mesh
filter after coagulation
No dramatic TMP increase occurred for all the tests For the raw sample TMP
increased steadily from 008 psi at the beginning to 038 psi at the fifth cycle and
maintained constant to the end of test Compared to the multi-cycle results of raw water
of Cintas (Figure 47) the Penn State laundry wastewater showed a less membrane
resistance probably due to its better water quality in terms of turbidity COD and TSS
For the CN sample no TMP increase was found throughout the experiment which
indicated that the pretreatment with Epi-DMA had improvement in reducing membrane
fouling The pre-filter after coagulation resulted in a better flux profile in MF compared
to the pre-filter applied before chemical dosing
0
1
2
3
0 20 40 60 80 100 120 140
TM
P (
ps
i)
Specific permeate volume (L m-2)
Raw sample
Super Underdosing (5ppm)
Charge Neutralization (40ppm)
65
59 SWRS RO Membrane cleaning procedure and SEMEDS analysis
591 RO fouling during operation
RO scaling was found the first day to process Penn State laundry wastewater in
SWRS while the whole system was in good condition in dealing with tap water at
various flow rates in the previous tests The pre-treatment of RO included coagulation
pre-filtration (15 μm) and MF (022 μm) Both of the TMP and flow rate of MF stayed
constant during operation However TMP of RO increased from 180 psi to around 290
psi within the first half an hour treatment and the permeate flow rate of RO decreased
from 8 gpm to 4 gpm (Appendix G Table G1 G2 ) Targeted dosage (UD) of Epi-
DMA was applied in the pre-treatment by conducting a coagulation process to enhance
the MF performance The ZP of the water passing through was maintained slightly
negative based on a titration test on the same water which was performed before chemical
addition into the bladder
592 RO membrane autopsy and sample preparation
One RO element (the middle one in the three-RO-vessel series) was dismantled from
SWRS based on the instruction of SWRS manual
Approximate 2 inches section (in width) of RO was cut out perpendicular to the water
flow direction by a miter saw The fouled RO membrane culled around the core was
easily drawn out and cut into pieces for the following experiments
593 SEM images
One section of fouled RO membrane was removed from the unit for an autopsy to
identify the foulants on the membrane FESEM was applied to analyze the surface
characteristics of raw membrane at Penn State without any cleaning pre-treatment
Various shapes of the foulants were observed on the fouled membrane Figure 512-514
shows certain kinds of foulants with similar physical characteristics In order to increase
the resolution of SEM images one set of the fouled membrane was pretreated by Au
sputtering to increase the electric conductivity of the organic membrane polymer
66
However the results showed little enhancement in the image resolution compared to that
found in the iron sputtered sample (Figure 515 Figure 516)
594 EDS analysis
To better understand the reason of fouling EDS was applied to analyze the elements
of the foulants In addition to the general area where membrane fouling was more
homogenous (Figure 515 b) the EDS test should also target specific materials that were
widely seen across the membrane surface such as the ball-shaped particles in Figure 513
and Figure 514 Inorganic elements (calcium silica etc) are anticipated to be seen on
the membrane surface
67
Figure 512 SEM images of the fouled RO membrane without Au sputtering a) 03 k x b) 10
kx
a)
b)
68
Figure 513 SEM images of the fouled RO membrane without Au sputtering c) 583 kx d) 845
kx
d)
c)
69
Figure 514 SEM images of the fouled RO membrane without Au sputtering a) 311 kx d) 612
kx
b)
a)
70
Figure 515 SEM images of the fouled RO membrane with Au sputtering a) 442 kx b) 938 kx
b)
a)
71
Figure 516 SEM images of the fouled RO membrane where there may have been less fouling a)
574 kx d) 1157 kx The membrane was pre-treated by Au sputtering
b)
a)
72
595 TEM images
The cross-section of the fouled RO membrane was viewed by TEM and the images
are shown in Figure 518 In general the structure of RO membrane consists of (1) a
thin-film (several nanometers) composite active layer of polyamide (PA) or polyvinyl
alcohol derivative (PVA) (2) a supportive layer (micrometers) of polysulfone or
polyethersulfone and (3) polyester backing fabric (Ghosh et al 2008) (Jeong et al
2007) In this study only two polymer layers with distinguished structure characters
were found in the cross-section image (Figure 518 d) Figure 518 (c) showed a pure and
homogeneous layer and indicated this layer which consisted of one type of polymer
probably was the supportive layer A composite layer of copolymers or other mixtures
(Figure 518 a b) was attached to the supportive layer The thickness for both of the two
layers was larger than 1 microm However additional information (ICP EDS etc) about the
RO fouling is needed for further analysis on the cross-section characteristics
73
Figure 517 TEM images of the cross-section of the fouled RO membrane
c)
a)
b)
b)
Supportive layer
Composite layer
2000 nm
74
596 RO cleaning and cleaning solutions
The membrane samples in pieces with a weight of 004 g per section were cleaned by
chemical soak (Table 51) prior to EDS tests and the solution after chemical soak (sample
1-4) was delivered for Ca Mg Fe Al and Si measurement using inductively coupled
plasma (ICP)
Sample 1 and 2 were treated with citric acid and hydrochloric acid for removing
inorganic scale (eg calcium carbonate calcium sulfate barium sulfate strontium sulfate)
and metal oxideshydroxides (eg iron manganese nickel copper zinc) and inorganic-
based colloidal material Hydrochloric acid solution (pH 25) used in sample 2 is
considered a harsher chemical solution than citric acid solution in sample 1 Sodium
hydroxide solution (pH 115) for sample 3 is a harsh cleaning solution to remove
polymerized silica and organic foulants
After chemical cleaning all samples were separately kept in petri dishes which were
sealed with plastic film wrapped with aluminum foil and prepared for shipping in a
hard plastic container
Table 51 RO cleaning solution and cleaning procedures for sample being shipped
Sample Quantity Cleaning Solution Cleaning procedure
0 2 NA No cleaning
1 1 Citric Acida Soak overnight
2 1 HClb Soak overnight 3 1 NaOHc Soak overnight
4 1 DI water Soak overnight
5 1 Citric Acid+NaOH Citric Acid 2hr + NaOH soak overnight 6 1 HCl+NaOH HCl 2hr + NaOH soak overnight
7 1 NaOH+Citric Acid NaOH 2hr + HCl soak overnight 8 1 NaOH+HCl NaOH 2hr + Citric Acid soak overnight a A low pH solution of 20 (w) citric acid (C6H8O7) b A low pH cleaning solution (target pH of 25) of 20 (w) of HCL (hydrochloric) acid c A high pH cleaning solution (target pH of 115) of 01 (w) of NaOH (sodium hydroxide)
Samples 1-8 are flushed with DI water then dried at 45degC for 2hr before packed and shipped
75
597 Cleaning solution analysis
After chemical cleaning the concentration of inorganic elements (Al Ca Fe Mg Si)
left in the solution are shown in Table 52 The concentrations of Ca (246 ugmL) and
Mg (019 ugmL) from NaOH solution were clearly less than the concentration in the
other three solutions The highest concentration for Ca (738 ugmL) was the found in
the HCl (pH 25) compared to other solution The concentration of Al Fe and Si were
insignificant in all the samples
The results indicated that the inorganic fouling by CaCO3 probably was the main
reason for RO fouling since the highest concentration of Ca was shown in the strongest
acid cleaning solution (HCL pH 25) for RO
Table 52 Concentration of the inorganic elements left in the cleaning solution after the
fouled RO membrane was cleaned
Sample number
Soak Solution
Al (ugmL)
Ca (ugmL)
Fe (ugmL)
Mg (ugmL)
Si (ugmL)
1
Citric
Acid lt02 71 005 045 027
2 HCl lt02 738 003 046 024
3 NaOH lt02 246 lt02 019 029
4 DI water lt02 7 lt02 035 024
76
510 Summary
The full-scale tests for laundry wastewater reuse were conducted by SWRS which
consisted pre-filter (15 μm mesh) MF (02 μm PVDF) RO GAC filter and UV light
Before the water flew into the treatment unit targeted polymer dosage was directly added
into the 3K bladder which contained laundry wastewater from Penn State Laundry
Building
The whole system was in good condition in processing tap water first at various flow
rates for calibration During laundry wastewater treatment negligible membrane fouling
was observed on MF for CN UD OD and raw water conditions Compared to the lab
results the difference of MF performance in the full-scale tests might due to (1) the water
sample applied in SWRS was different in quality (TSS COD pH turbidity) from the
water sample collected from Cintas in the lab experiments (2) the pre-filter reduced the
load on the downstream MF in SWRS (3) the backwashing conducted by SWRS was
more rigorous than applied in the lab work (4) a significant amount of lint particles and
floc which contained remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an extra coagulation process to the low dosed or
raw water sample conducted at the end of test and might lead to an imprecise dosing
condition
However for raw water and super UD condition where the effective coagulation had
not been triggered severe fouling was found in pre-filter and resulted in flow rate drops
at the beginning 10-30 min of the test
In addition RO scaling was observed on the first day for laundry wastewater
treatment The precipitation of CaCO3 was considered as the main reason of RO fouling
The foulant identification and RO recovery study is still under investigation
77
CHAPTER 6 CONCLUSIONS
The primary objective of this study was to systematically evaluate the application of
the combined technologies of coagulation and membrane filtration for re-use of laundry
wastewater from bench scale experiments to full scale operation The potential of using
cationic polymeric coagulants to reduce membrane fouling in laundry wastewater (with
high pH high TSS and high COD) treatment was investigated The full scale
experiments were conducted by SWRS an Armyrsquos full-scale unit which included pre-
filter (15 microm) MF (022 microm) RO and GAC etc Additional work was carried out to
discuss the problems which might be faced during the application of the hybrid treatment
as well as to develop a better understanding of the interactions between the residual
foulants and RO scaling
61 Polymer selection for laundry wastewater treatment
In the coagulationsedimentation tests compared to the conventional coagulants and
certain kinds of polymeric coagulants NALCOLYTE 8105 (Epi-DMA) and CAT-FLOC
8108 Plus (PDADMAC) were proven to be the most favourable coagulants in
contaminants removal (COD TSS turbidity) for laundry wastewater treatment in both
high and neutralized pH conditions However only 10-30 TP removal rate was
observed in the coagulationsedimentation tests for all polymers The polyquaternary
amine Epi-DMA was selected as the targeted polymer for further tests because it
showed the best effect on MF in reducing the specific resistance and cake compressibility
during MF (022 microm) directly after coagulation by several of polymers
62 Bench scale MF experiments
In order to determine the effects of the selected polymeric coagulant (Epi-DMA) on
MF performance over longer-term membrane filtration operating cycles with
backwashing multi-cycle MF experiments were conducted after targeted dosage of Epi-
DMA was added to the wastewater sample prior to MF to provide a broad range of
coagulation regimes (UD CN OD) The dead-end MF tests were applied first to identify
the critical flux for each dosing condition
78
Compared to the CN (ZP raised to zero by polymer dosing) condition which had the
best coagulation performance in terms of removal of COD (63) TSS (77) turbidity
(96) and TP (26) the UD regime save the chemical usage by 40 while maintaining
a similar removal rates of COD (60) TSS (74) turbidity (86) and TP (8)
Pre-coagulation using the Epi-DMA polymer NALCOLYTE 8105 resulted in large
increases in the measured critical flux values from 50 L m-2 hr-1 for the raw sample to
around 450 L m-2 hr-1 for the CN condition The critical flux was 300 L m-2 hr-1 for the
OD condition where the dosage was twice as high as for the CN condition These results
indicated that pre-coagulation MF could result in significantly higher permeate flux thus
decreasing the required MF footprint for a given wastewater flow
Taking into account of the effect of backwashing the long-term MF filtration tests
with multi-cycles showed that membrane fouling was still building up with filtration time
even though the permeate flux was controlled below the critical flux Negligible
membrane fouling was observed for UD and CN conditions at 50 L m-2 hr-1 (permeate
flux) which was the suggested permeate flux value for full-scale operation with SWRS
OD condition should be avoided since irreversible fouling might be accumulated on the
PVDF membrane and resulted in TMP increase over long-term operation For the raw
water membrane fouling was observed and kept building up within each 15 min filtration
cycle but a high TMP recovery (almost 100) occurred after flushing and backwashing
with DI water Better removal of turbidity TSS and COD were achieved using
coagulationMF than had been observed using coagulationsedimentation
The results showed the pre-treatment with coagulant addition was needed to decrease
MF fouling and for higher permeate volume The chemical dosage should be controlled
in the range from UD to slightly OD conditions
79
63 Full-scale tests and RO scaling
The full-scale tests by SWRS demonstrated that negligible MF fouling was occurred
in treating the wastewater from Penn State Laundry Building for a range of dosing
conditions (UD CN and slight OD) including raw water sample However the results
showed the pre-treatment with coagulant addition was needed to decrease pre-filter
fouling and to increase permeate volume because fouling occurred on the pre-filter and
led to significant decline in flow rate when the water passing through SWRS was
untreated or the coagulant addition was too small to produce effective coagulation
The reason for the differences in performance in MF between the bench-scale
experiments and the full-scale operation could be (1) the laundry wastewater applied in
SWRS was collected from a smaller scale laundry with better water quality (lower
turbidity TSS and COD) than the water sample collected from Cintas (2) the pre-filter
reduced the load on the downstream MF in SWRS (3) the backwashing conducted by
SWRS was more rigorous than applied in the lab work (4) a significant amount of lint
particles and floc with remaining polymeric coagulants had been accumulated at the
bottom during operation and introduced an additional coagulation to the low dosed or raw
water sample which was applied in the last few tests and might lead to an imprecise
dosing condition
Serious fouling was observed in the RO unit and the formation of inorganic
precipitates was suspected as the main reason for RO failure Issues regarding MF and
RO behavior in the full-scale SWRS are still under investigation
80
CHAPTER 7 RECOMMENDATIONS
This study showed that over-dosed of the cationic polymer Epi-DMA increased the
irreversible fouling on the PVDF membrane Long time operation (couple of days) with
backwash for UD and CN conditions is recommended to investigate the application of
cationic polymer to enhance MF performance in laundry wastewater treatment
Future studies could be conducted with
Chemical cleaning and flux recovery test on the MF membrane
Long-time filtration experiment
Other types of coagulant and pH conditions in the pre-treatment
Other types of membrane and filtration configuration (eg cross-flow hollow fiber
etc)
RO foulant determination RO cleaning and flux recovery
This study was conducted with high alkalinity laundry wastewater It is also
recommended to test on other water sources or the water combined with laundry and
shower discharges
81
REFERENCES
Acero JL Benitez FJ Leal AI Real FJ Teva F 2010 ldquoMembrane filtration
technologies applied to municipal secondary effluents for potential reuserdquo J
Hazard Mater 177 390-398
APHA 2005 ldquoStandard methods for the examination of water and wastewaterrdquo
American Public Health Association 21st ed Washington
Ba er RW 2004 ldquoMembrane Technology and Applicationrdquo Wiley Chichester
Can OT Bayramoglu M Kobya M 2003 ldquoDecolorization of reactive dye
solutions by electrocoagulation using aluminum electrodesrdquo Ind Eng
ChemRes 42 3391-3396
Chang IS Clech PL Jefferson B Judd S 2002 ldquoMembrane fouling in
membrane bioreactors for wastewater treatmentrdquo Journal of environmental
engineering 128 1018
Choi KYJ Dempsey BA (2004) ldquoIn-line coagulation with low-pressure
membrane filtrationrdquo Water Research 38 (19) 4271-4281
Dentel SK 1991 ldquoCoagulant control in water treatmentrdquo Environmental Science
and Technology 21 (1) 41-135
Elzo D Elzo D Huisman I Middelink E Gekas V 1998 ldquoCharge effects on
inorganic membrane performance in a cross-flow microfiltration processrdquo
Colloids and Surfaces A Physicochemical and Engineering Aspects 138 (2-3)
145ndash159
Farid NR Anderson J (1972) ldquoA low pressure system for membrane filtration for
use in micronephelometryrdquo Clinica chimica acta international journal of
clinical chemistry 39 (1) 263-265
82
Field RW et al 1995 ldquoCritical flux concept for microfiltration foulingrdquo Journal
of Membrane Science 100 (3) 259ndash272
Greywater in General SHOMERA for a better environment Retrieved on 20th
March 2012 from
httpwwwshomeraorgengreywater-generalhtm
Ghosh AK Jeong BH Huang X Hoe EM 2008 ldquoImpacts of reaction and
curing conditions on polyamide composite reverse osmosis membrane
propertiesrdquo Journal of Membrane Science 34-45
Guibaud J Masse A Andres Y Combe F Jaouen P 2010 ldquoLaundry water
recycling in ship by direct nanofiltration with tubular membranesrdquo Resources
Conservation and Recycling 55 148-154
Hoin is J Panten V 2007 ldquoWastewater recycling in laundries-From pilot to large-
scale plantrdquo Chemical Engineering and Processing 47 (7) 1159ndash1164
Howell John A (1995) ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Howell JA 1995 ldquoSub-critical flux operation of microfiltrationrdquo Journal of
Membrane Science 107 (1-2) 165-171
Huang H Young TA Jacangelo JG (2008) ldquoUnified membrane fouling index
for low pressure membrane filtration of natural waters principles and
methodologyrdquo Environmental science technology 42 (3) 714-720
Jaeger W Bohrisch J Laschews y A 2010 ldquoSynthetic polymers with quaternary
nitrogen atoms-Synthsis and structure of the most used type of cationic
polyelectrolytesrdquo Progress in Polymer Science 35 511-577
83
Janpoor F Torabian A and Khatibi amal V 2011 ldquoTreatment of Laundry
Waste-water by Electrocoagulationrdquo Journal of Chemical Technology and
Biotechnology 86 1113-1120
Jeong BH Hoek EM Yan Y Subramani A Huang X Hurwitz G (2007)
ldquoInterfacial polymerization of thin film nanocomposites A new concept for
reverse osmosis membranesrdquo Journal of Membrane Science 1-7
Kim HC Dempsey BA (2008) ldquoEffects of wastewater effluent organic materials
on fouling in ultrafiltrationrdquo Water research 42 (13) 3379ndash3384
Kim HC Dempsey BA (2010) ldquoRemoval of organic acids from EfOM using
anion exchange resins and consequent reduction of fouling in UF and MFrdquo
Journal of Membrane Science 364 (1-2) 325-330
Kim J DiGiano FA 2006 ldquoDefining critical flux in submerged membranes
Influence of length-distributed fluxrdquo J Membr Sci 280 752-761
Kim S H Moon B H and Lee H I 2001 ldquoEffects of pH and Dosage on
Pollutant Removal and Floc Structure during Coagulationrdquo Microchem J 68
197-203
Lee B Choo K Chang D Choi S 2009 ldquoOptimizing the coagulant dose to
control membrane fouling in combined coagulationultrafiltration systems for
textile wastewater reclamationrdquo Chem Eng J 155 101-107
Lee JD Lee SH Jo MH Park PK Lee CH Kwak JW 2000 ldquoEffect of
coagulation conditions on membrane filtration characteristics in coagulation-
microfiltration process for water treatmentrdquo Environmental science amp
technology 34 (17) 3780ndash3788
84
Lipp p Muumlller U Hetzer B Wagner T (2009) ldquoCharacterization of
nanoparticulate fouling and breakthroughduring low-pressure membrane
filtrationrdquo Desalination and Water Treatment 9 234-240
Marcucci M Nosenzo G Capannelli G Ciabatti I Corrieri D Ciardelli G
2001 ldquoTreatment and reuse of textile effluents based on new ultrafiltration and
other membrane technologiesrdquo Desalination 138 75-82
Field RW Wu D Howell JA Gupta BB (1995) ldquoCritical flux concept for
microfiltration foulingrdquo Journal of Membrane Science 100 (3) 259-272
Ripperger S Altmann J (2002) ldquoCrossflow microfiltration-state of the artrdquo
Separation and Purification Technology 26 (1) 19ndash31
Rossini M Garrido JG Galluzzo M (1999) ldquoOptimization of the coagulation
flocculation treatment influence of rapid mix parametersrdquo Water Research 33
(8) 1817-1826
Sanchez Sanchez A Garrido JM Mendez R 2010 ldquoA comparative study of
tertiary membrane filtration of industrial wastewater treated in a granular and
flocculent sludge SBRrdquo Desalination 250 810-814
Sharp E L Parsons S A and Jefferson B 2006 ldquoThe Impact of Seasonal
Variations in DOC Arising from a Moorland Peat Catchment on Coagulation
with Ironandaluminium Saltsrdquo Environ Pollut 140 (2) 436-443
Sojka-Ledakowicz J Koprowski T Machnowski W Knusdsen HH (1998)
ldquoMembrane filtration of textile dye-house wastewater for technological water
reuserdquo Desalination 119 1-10
85
Sostarturk I P Simonic M (2005) ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resources Conservation and Recycling
44 (2) 185-196
Sostar-Tur S Petrinic I Simonic M 2005 ldquoLaundry wastewater treatment using
coagulation and membrane filtrationrdquo Resou Conse Recyc 44 185-196
Stephen T Judd SJ Brindle K 2000 ldquoMembrane Bioreactors for Wastewater
Treatmentrdquo IWA Publishing London UKStumm W 1992 ldquoChemistry of the
Solid-Water Interfacerdquo John Wiley and Sons New York
Termonia Y (1995) ldquoFundamentals of polymer coagulationrdquo Journal of Polymer
Science Part B Polymer Physics 33 (2) 279-288
Tiller FM 1990 ldquoTutorial interpretation of filtration data Irdquo FluidParticle
Separation Journal 90 85-94
Timmes TC Kim HC Dempsey BA (2010) ldquoElectrocoagulation pretreatment of
seawater prior to ultrafiltration Pilot-scale applications for military water
purification systemsrdquo Desalination 250 (1) 6-13
Trejo-Gaytan JT P Bachard and J Darby 2006 ldquoTreatment runoff at La e Tahoe
Low-intensity chemical dosingrdquo Water Env Res78 2498-2500
Wang C Chou W Kuo Y 2009 ldquoRemoval of COD from laundry wastewater by
electrocoagulationelectroflotationrdquo J Hazard Mater 164 81-86
Wintgens T Melin T Schafer A Khan S Muston S Bixio D Thoeye C
2005 ldquoThe role of membrane processes in municipal wastewater reclamation
and reuserdquo Desalination 178 1-11
86
Appendix A Material and Water Quality changes in Bench
Scale Experiments
Table A1 General characteristics of membranes (Stephenson et al 2000)
Membrane
Operation
Pore Size
Range
(Microns)
Operating
Pressure
(kPa)
Molecular
Weight Cutoff
Range (Da)
Mechanism
Separation
Driving
Force
Microfiltration 01-10 7-208 gt100 000 Sieve Pressure or
vacuum
Ultrafiltration 001-01 21-551 gt2000-100 000 Sieve Pressure
Nanofiltration 0001-001 283-1516 300-1000
Sieve + Solution
Diffusion +
Exclusion
Pressure
Reverse
Osmosis lt0001 6612-8268 100-200
Solutiondiffusion
+ Exclusion Pressure
Table A2 Cintas laundry wastewater quality changes by MF with different pre-
treatments
The TSS tests for the filtrate of MF were negligible by using a 01 microm glass filter and not shown
in the list
Parameter
Raw
Waste
water
Pretreated
with 10 um
PP filter
Filtrate
(UD)
Filtrate
(CN)
Filtrate
(OD)
pH 1103 1103 1102 1096 1087
Conductivity (μS cm-1
) 1360 1390 1193 1040 1139 Turbidity(NTU) 658 638 023 071 022
COD(mg L-1) 1196 1162 356 406 488
TP (mg PO43-L) 704 698 604 624 64
TP (mg TPL) 100 99 86 89 90
TSS (mg L-1
) 300 260
87
Table A3 Polymers from Cintas Company
Name Description Name Description
Pack (10) 480-P291588
4 ULTIMERreg 1470 acrylic polymer
1 NACOLYTEreg 8100 EPI DMA 5 ULTIMERreg 1460 MW-high water-based cationic polyacrylamide
2 NACOLYTEreg 8105 EPI DMA Pack (2) unknown
3 NACOreg 8190 amphoteric 1 IronGUARDreg 2495 Amphoteric acrylic polymer
4 CAT-FLOC 8102 PLUS DADMAC 2 NACOreg 2490 Amphoteric acrylic polymer
5 CAT-FLOC 8103 PLUS DADMAC Pack (9) 480-P612088
6 CAT-FLOC 8108 PLUS DADMAC 1 71300 FLOCCULANT 50 cationic
7 8799 LS COAGULANT DADMAC 2 CORE SHELLreg 71301 50 cationic
8 CAT-FLOCreg 8799 PLUS DADMAC 3 CORE SHELLreg 71303 30 cationic
9 CAT-FLOCreg LS DADMAC 4 CORE SHELLreg 71305 10 cationic
10 NACOreg 71257 polymer 5 CORE SHELLreg 71306 65 cationic
Pack (5) 480-P289788 6 CORE SHELLreg 71307 65 cationic
1 ULTIMERreg 7757 acrylic polymer 7 CORE SHELLreg 71315 5 cationic
2 ULTIMERreg 7751 charge-medium MW-high 8 CORE SHELLreg 71325 30 anionic
3 ULTIMERreg 7752 charge-high MW-high 9 CORE SHELLreg 71321 50 cationic
88
Table A4 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Penn State Laundry Wastewater
RPM Time (min) G (s-1
)
Sample PennState Laundry
WW 500 mL Rapid mix 120 20 asymp 240
Temperature 223 Co
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 025 05 15 25 45
Concentration microLL 0 5 10 30 50 89
AFTER RAPID MIX
pH aadjustment 1042 1038 1038 1036 1036 1032
Zeta potential mV -29 -152 -821 105 351 617
-302 -163 -906 078 371 667
-319 -149 -989 06 374 64
-316 -183 -10 092 337 62
Average mV -307 -162 -93 08 36 64
STD mV 13 15 08 02 02 02
AFTER SETTLING
Turbidity NTU 724 828 539 378 426 474
71 829 547 384 408 474
Average NTU 72 83 54 38 42 47
STD NTU 1 0 1 0 1 0
Residual AVE 100 116 76 53 58 66
STD 28 15 22 20 32 14
TSS bfiltration g 0081 0086 00867 0086 00871 00847
afiltration g 00881 00886 00893 0088 00878 0087
sample vol mL 30 30 30 30 30 30
mgL 237 87 87 67 23 77
Residual AVE 100 37 37 28 10 32
COD mgL 332 312 249 232 263 238
Dilution times 1 332 312 249 232 263 238
Residual AVE 100 94 75 70 79 72
TP mg PO43-
L 243 235 232 229 232 231
Dilution times 40 972 94 928 916 928 924
Residual AVE 100 97 95 94 95 95
mg TPL 079 077 076 075 076 075
Dilution times 40 316 308 304 30 304 30
Residual AVE 100 97 96 95 96 95
89
Table A5 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 Plus in treating Penn State Laundry Wastewater
RPM Time (min) G (s
-1)
Sample PSU Laundry WW 500 mL Rapid mix 120 20 asymp 240
Polymer CAT-FLOC 8108 Plus 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 05 1 15 2 25
Concentration microLL 0 10 20 30 40 50
AFTER RAPID MIX
pH aadjustment 1042 1039 104 1039 1039 1038
Zeta potential mV -29 -151 -529 0322 624 133
-302 -159 -699 0321 571 125
-319 -166 -722 -03 544 123
-316 -171 -727 0168 591 121
Average mV -307 -162 -67 01 58 126
STD mV 13 09 09 03 03 05
AFTER SETTLING
Turbidity NTU 724 749 254 199 279 489
71 783 253 197 283 511
Average NTU 72 77 25 20 28 50
STD NTU 1 2 0 0 0 2
Residual AVE 100 107 35 28 39 70
STD 28 47 15 16 18 36
TSS bfiltration g 0081 00895 0089 00874 00864 00855
afiltration g 00881 00916 00896 00874 00876 00878
sample vol mL 30 30 30 30 30 30
mgL 237 70 20 0 40 77
Residual AVE 100 30 8 0 17 32
COD mgL 332 287 188 189 211 251
Dilution times 1 332 287 188 189 211 251
Residual AVE 100 86 57 57 64 76
TP mg PO43-
L 242 231 231 229 231 232
Dilution times 40 968 924 924 916 924 928
Residual AVE 100 95 95 95 95 96
mg TPL 078 075 075 075 075 076
Dilution times 40 312 30 30 30 30 304
Residual AVE 100 96 96 96 96 97
90
Table A6 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 16 20
Concentration microLL 0 79 157 234 310 385
AFTER RAPID MIX pH aadjustment 1103 1088 1094 1093 1091 109
Zeta potential mV -576 -276 -167 207 123 185
-586 -27 -175 -274 108 174
-61 -269 -184 175 107 166
-576 -283 -182 155 944 168
Average mV -587 -275 -177 07 108 173
STD mV 16 06 08 23 12 09
AFTER SETTLING Turbidity NTU 332 213 12 108 534 401
332 212 11 108 535 402
Average NTU 332 213 12 108 535 402
STD NTU 0 1 1 0 1 1
Residual AVE 100 64 3 33 161 121
STD 00 02 02 00 02 02
TSS bfiltration g 00917 00914 00923 00913 0091 00887
afiltration g 00972 0095 00946 0094 00987 00954
sample vol mL 30 30 30 30 30 30
mgL 183 120 77 90 257 223
Residual AVE 100 65 42 49 140 122
COD mgL 380 280 164 235 394 425
Dilution times 2 760 560 328 470 788 850
Residual AVE 100 74 43 62 104 112
TP mg PO43-
L 244 237 24 224 219 239
Dilution times 20 488 474 48 448 438 478
Residual AVE 100 97 98 92 90 98
mg TPL 08 077 078 073 071 078
Dilution times 20 16 154 156 146 142 156
Residual AVE 100 96 98 91 89 98
91
Table A7 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 4 8 12 20 20
Concentration microLL 0 79 157 234 385 385
AFTER RAPID MIX
pH aadjustment 1101 106 1043 1022 996 996
Zeta potential mV -573 -397 -12 -568 -125 -125
-598 -363 -12 -465 -143 -143
-612 -406 -109 -486 -139 -139
-579 -378 -129 -43 -156 -156
Average mV -591 -386 -120 -49 -14 -14
STD mV 18 19 08 06 01 01
AFTER SETTLING
Turbidity NTU 475 146 95 63 240 240
475 146 95 62 240 240
Average NTU 475 146 95 63 240 240
STD NTU 0 0 0 1 0 0
Residual AVE 100 31 20 13 51 51
STD 00 00 00 01 00 00
TSS bfiltration g 00911 0092 0092 00907 0093 0093
afiltration g 00964 00942 00945 00928 00989 00989
sample vol mL 30 30 30 30 30 30
mgL 177 73 83 70 197 197
Residual AVE 100 42 47 40 111 111
COD mgL 466 319 265 225 330 350
Dilution times 2 932 638 530 450 660 700
Residual AVE 100 68 57 48 71 75
TP mg PO43-
L 265 255 25 243 237 234
Dilution times 20 53 51 50 486 474 468
Residual AVE 100 96 94 92 89 88
mg TPL 087 085 082 079 077 076
Dilution times 20 174 17 164 158 154 152
Residual AVE 100 98 94 91 89 87
92
Table A8 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 21 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 6 9 12 15
Concentration microLL 0 60 119 177 234 291
AFTER RAPID MIX
pH aadjustment 1096 1063 1065 1064 1062 1057
Zeta potential mV -57 -442 -711 -391 -287 -273
-565 -464 -77 -5 -408 -35
-617 -499 -799 -546 -479 -443
-59 -501 -679 -571 -558 -498
Average mV -586 -477 -74 -50 -43 -39
STD mV 24 29 05 08 12 10
AFTER SETTLING
Turbidity NTU 492 87 13 26 35 35
491 87 13 26 35 34
Average NTU 492 87 13 26 35 35
STD NTU 1 0 0 0 0 1
Residual AVE 100 18 3 5 7 7
STD 03 01 01 01 01 03
TSS bfiltration g 00927 00914 00919 00928 00927 00924
afiltration g 00962 00918 00923 00932 00933 00933
sample vol mL 30 30 30 30 30 30
mgL 117 13 13 13 20 30
Residual AVE 100 11 11 11 17 26
COD mgL 496 235 161 164 160 150
Dilution times 2 992 470 322 328 320 300
Residual AVE 100 47 32 33 32 30
TP mg PO43-
L 313 264 25 231 249 242
Dilution times 20 626 528 50 462 498 484
Residual AVE 100 84 80 74 80 77
mg TPL 102 086 081 075 081 079
Dilution times 20 204 172 162 15 162 158
Residual AVE 100 84 79 74 79 77
93
Table A9 Data obtained from the coagulationprecipitation experiment by ULTIMER
1460 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 223 Co
Rapid mix 130 30 asymp 240
Polymer ULTIMER 1460 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 5 8 10 15
Concentration microLL 0 60 99 157 196 291
AFTER RAPID MIX
pH aadjustment 72 74 744 747 747 745
Zeta potential mV -557 -497 -241 -801 -164 699
-589 -516 -242 -759 -119 731
-584 -496 -233 -811 -128 751
-587 -484 -243 -727 -155 801
Average mV -579 -498 -240 -77 -14 75
STD mV 15 13 05 04 02 04
AFTER SETTLING
Turbidity NTU 730 263 254 86 54 510
729 261 251 76 59 511
Average NTU 730 262 253 81 57 511
STD NTU 1 1 2 7 4 1
Residual AVE 100 36 35 11 8 70
STD 02 03 04 11 06 02
TSS bfiltration g 00832 00885 00909 00905 00901 00884
afiltration g 00921 00941 00945 00934 00934 00996
sample vol mL 30 30 30 30 30 30
mgL 297 187 120 97 110 373
Residual AVE 100 63 40 33 37 126
COD mgL 846 618 590 404 378 545
Dilution times 2 1692 1236 1180 808 756 1090
Residual AVE 100 73 70 48 45 64
TP mg PO43-
L 368 363 361 362 358 351
Dilution times 20 736 726 722 724 716 702
Residual AVE 100 99 98 98 97 95
mg TPL 12 118 118 118 117 115
Dilution times 20 24 236 236 236 234 23
Residual AVE 100 98 98 98 98 96
94
Table A10 Data obtained from the coagulationprecipitation experiment by CORE
SHELL 71301 in treating Cintas Laundry Wastewater
Date 10212010 Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CORE SHELL 71301 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 3 4 5 6
Concentration microLL 0 40 60 79 99 119
AFTER RAPID MIX
pH aadjustment 717 749 76 767 767 766
Zeta potential mV -576 -491 -359 -193 -416 232
-603 -508 -37 -195 -41 211
-604 -509 -347 -22 -467 108
-595 -519 -35 -21 -526 149
Average mV -595 -507 -357 -205 -45 18
STD mV 13 12 10 13 05 06
AFTER SETTLING
Turbidity NTU 619 253 193 139 30 6
619 252 193 139 29 6
Average NTU 619 253 193 139 30 6
STD NTU 0 1 0 0 1 0
Residual AVE 100 41 31 22 5 1
STD 00 01 00 00 01 00
TSS bfiltration g 00921 00891 00902 00879 00903 00919
afiltration g 00962 00931 00921 00922 00915 00919
sample vol mL 30 30 30 30 30 30
mgL 137 133 63 143 40 0
Residual AVE 100 98 46 105 29 0
COD mgL 763 543 378 274 205 161
Dilution times 2 1526 1086 756 548 410 322
Residual AVE 100 71 50 36 27 21
TP mg PO43-
L 389 357 35 348 33 325
Dilution times 20 778 714 70 696 66 65
Residual AVE 100 92 90 89 85 84
mg TPL 127 116 114 113 108 106
Dilution times 20 254 232 228 226 216 212
Residual AVE 100 91 90 89 85 83
95
Table A11 Data obtained from the coagulationprecipitation experiment by CAT-FLOC
8108 PLUS in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s
-1)
Temperature 251 Co
Rapid mix 130 30 asymp 240
Polymer CAT-FLOC 8108
PLUS 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 3 7 10 15 20
Concentration microLL 0 60 138 196 291 385
AFTER RAPID MIX
pH aadjustment 711 75 753 76 759 759
Zeta potential mV -529 -292 -109 -503 -106 086
-524 -299 -108 -501 -077 085
-534 -305 -111 -523 -112 07
-501 -294 -108 -471 -119 08
Average mV -522 -298 -109 -50 -10 08
STD mV 15 06 01 02 02 01
AFTER SETTLING
Turbidity NTU 650 627 254 90 80 115
648 626 253 91 80 112
Average NTU 649 627 254 91 80 114
STD NTU 1 1 1 1 0 2
Residual AVE 100 97 39 14 12 17
STD 04 03 03 03 02 05
TSS bfiltration g 0090
4 0090
7 00905 0090
5 00906 0090
4
afiltration g 0095
2 0095
6 00946 0093 00925 0093
6
sample vol mL 30 30 30 30 30 30
mgL 160 163 137 83 63 107
Residual AVE 100 102 85 52 40 67
COD mgL 798 765 419 327 336 344
Dilution times 2 1596 1530 838 654 672 688
Residual AVE 100 96 53 41 42 43
TP mg PO43-
L 379 359 342 327 286 281
Dilution times 20 758 718 684 654 572 562
Residual AVE 100 95 90 86 75 74
mg TPL 124 117 112 107 093 092
Dilution times 20 248 234 224 214 186 184
Residual AVE 100 94 90 86 75 74
96
Table A12 Data obtained from the coagulationprecipitation experiment by
NACOLYTE 8105 in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature
Co
Rapid mix 130 30 asymp 240
Polymer NACOLYTE 8105 1 Settling NA 60 NA
Item
Raw 1 2 3 4 5
Polymer dose mL 0 2 4 6 8 11
Concentration microLL 0 40 79 119 157 215
AFTER RAPID MIX
pH aadjustment 716 795 797 799 797 797
Zeta potential mV -463 -22 -952 -376 -152 002
-474 -225 -104 -361 -16 002
-464 -213 -104 -373 -189 001
-458 -23 -982 -42 -186 0
Average mV -465 -222 -100 -38 -17 00
STD mV 07 07 04 03 02 00
AFTER SETTLING
Turbidity NTU 647 701 298 68 43 40
646 699 300 68 40 39
Average NTU 647 700 299 68 42 40
STD NTU 1 1 1 0 2 1
Residual AVE 100 108 46 11 6 6
STD 02 03 03 01 04 02
TSS bfiltration g 00886 00904 00906 00904 00913 00904
afiltration g 00957 00968 00943 00918 00926 00919
sample vol mL 30 30 30 30 30 30
mgL 237 213 123 47 43 50
Residual AVE 100 90 52 20 18 21
COD mgL 818 760 443 344 307 338
Dilution times 2 1636 1520 886 688 614 676
Residual AVE 100 93 54 42 38 41
TP mg PO43-
L 368 378 341 337 318 323
Dilution times 20 736 756 682 674 636 646
Residual AVE 100 103 93 92 86 88
mg TPL 12 123 111 11 104 105
Dilution times 20 24 246 222 22 208 21
Residual AVE 100 103 93 92 87 88
97
Table A13 Data obtained from the coagulationprecipitation experiment by NACO 2490
in treating Cintas Laundry Wastewater
Sample CINTAS Laundry WW 500 mL
RPM Time (min) G (s-1
)
Temperature 252 Co
Rapid mix 130 30 asymp 240
Polymer NACO 2490 1 Settling NA 60 NA
Item Raw 1 2 3 4 5
Polymer dose mL 0 2 5 8 10 13
Concentration microLL 0 40 99 157 196 253
AFTER RAPID MIX
pH aadjustment 72 746 753 754 756 754
Zeta potential mV -476 -35 -133 -311 -155 08
-452 -347 -132 -35 -177 085
-455 -339 -128 -33 -144 083
-451 -351 -129 -339 -129 071
Average mV -459 -347 -131 -33 -15 08
STD mV 12 05 02 02 02 01
AFTER SETTLING
Turbidity NTU 645 435 62 83 59 43
647 436 60 83 59 43
Average NTU 646 436 61 83 59 43
STD NTU 1 1 1 0 0 0
Residual AVE 100 67 9 13 9 7
STD 04 03 04 02 02 02
TSS bfiltration g 00913 00908 00913 00909 00932 00925
afiltration g 01 00951 00923 00924 00947 00936
sample vol mL 30 30 30 30 30 30
mgL 290 143 33 50 50 37
Residual AVE 100 49 11 17 17 13
COD mgL 762 643 302 280 271 226
Dilution times 2 1524 1286 604 560 542 452
Residual AVE 100 84 40 37 36 30
TP mg PO43-
L 371 366 353 348 341 339
Dilution times 20 742 732 706 696 682 678
Residual AVE 100 99 95 94 92 91
mg TPL 121 12 115 113 111 111
Dilution times 20 242 24 23 226 222 222
Residual AVE 100 99 95 93 92 92
98
Sample CINTAS Laundry
WW 500 mL
RPM Time (min) G (s-1) Temperature 40 degC
Rapid mix 130 30 asymp 240
Polymer NALCOLYTE 8105 1 Settling NA 60 NA Item Raw 1 2 3 4 5 6 7 8 9
Polymer dose mL 0 2 4 6 8 10 14 20 30 40
Concentration microLL 0 40 79 119 157 196 272 385 566 741
AFTER RAPID MIX pH aadjustment 72 74 744 747 747 745
Zeta potential mV -607 -318 -131 -446 -195 075 511 702 114 172
-638 -344 -128 -497 -184 0755 484 703 112 17
-667 -347 -135 -474 -193 0821 471 716 112 179
-659 -347 -139 -498 -219 0867 482 7 106 166
Average mV -643 -339 -133 -48 -20 08 49 71 111 172
STD mV 27 14 05 02 01 01 02 01 03 05
AFTER SETTLING Turbidity NTU 783 1000 506 106 50 30 35 82 161 539
785 1000 505 106 48 28 34 82 166 551
Average NTU 784 1000 506 106 49 29 35 82 164 545
STD NTU 1 0 1 0 1 1 1 0 4 8
Residual AVE 100 128 64 14 6 4 4 10 21 70 STD 04 02 03 02 04 04 03 02 06 13
TSS bfiltration g 00888 00882 00865 00885 00881 00866 00882 00882 00871 00885
afiltration g 00961 00971 00917 00904 00901 00883 00891 00893 00888 00937
sample vol mL 30 30 30 30 30 30 30 30 30 30
mgL 243 297 173 63 67 57 30 37 57 173
Residual AVE 100 122 71 26 27 23 12 15 23 71
COD mgL 589 608 357 237 227 216 250 320 372 549
Dilution times 2 1178 1216 714 474 454 432 500 640 744 1098
Residual AVE 100 103 61 40 39 37 42 54 63 93
TP mg PO43-L 356 379 321 326 291 265 267 274 279 299
Dilution times 20 712 758 642 652 582 53 534 548 558 598
Residual AVE 100 106 90 92 82 74 75 77 78 84
mg TPL 116 124 105 106 093 086 088 095 097 103
Dilution times 20 232 248 21 212 186 172 176 19 194 206
99
Table A14 Data obtained from the coagulationprecipitation experiment by NALCOLYTE 8105 in treating Cintas Laundry Wastewater
Residual AVE 100 107 91 91 80 74 76 82 84 89
100
Appendix B Example of Data Processing for Critical Flux
Determination Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 2 L
pH 11plusmn03
Temperature 22 degC
Sample Type 385 ppm (OD) with Epi-DMA
101
Table B1 Data processing for critical flux determination experiment
No Real
sampling Time
Cumulated
filtration time (sec)
Calibrated
filtration time-A (sec)
Calibrated
filtration time-B (min)
Unit
filtration time (min)
Feed
pressure (psi)
Permeate
pressure (psi)
TMP
(psi)
Calibrated
TMP (psi)
Mean
TMP (psi)
Permeate
weight (g)
Permeate
volume (mL)
Unit
permeate volume (mL)
Permeate
flux (L m
-2 hr
-1)
c
Mean
permeate flux (L m
-2 hr
-1)
0 162616 1128
1004 1000 004 002
0 1 162716 1188
1006 1004 002 000
0
2 162816 1248
1012 1010 002 000
0 3 162916 1308
1014 1012 002 000
0
4 163016 1368
1020 1018 002 000
0 5 163116 1428
1024 1024 000 -002
0
6 163216 1488
1026 1026 000 -002
0 7 163317 1548
1030 1026 004 002
0
8 163416 1608
1030 1030 000 -002
0 9 163517 1668
1030 1030 000 -002
0 Total Vol (mL)
10 163616 1728 1038 1032 006 004 002a 0 -142
0b 163717 1788 0 0
1038 1032
0 00 142
1 163816 1848 60 1 1 1036 1030 006 004
0 00 06 317
2 163917 1908 120 2 1 1036 1026 010 008
0 00 06 317
3 164016 1968 180 3 1 1036 1026 010 008
03 03 05 265
4 164117 2028 240 4 1 1036 1026 010 008
09 09 06 318
5 164216 2088 300 5 1 1030 102 006 004
15 15 06 318
6 164317 2148 360 6 1 1030 1026 004 002
2 20 05 265
7 164417 2208 420 7 1 1030 1026 004 002
26 26 06 318
8 164517 2268 480 8 1 1036 1026 010 008
32 32 06 318
9 164617 2328 540 9 1 1030 1026 004 002
38 38 06 318
10 164717 2388 600 10 1 1038 1030 008 006 005d 44 44 06 318 3075d
0 164817 2448 600 10
1026 1012
003 55 55
224
1 164917 2508 660 11 1 1006 992 014 012
82 82 27 1433
102
2 165017 2568 720 12 1 1000 982 018 016
107 107 25 1327 3 165117 2628 780 13 1 998 980 018 016
134 134 27 1433
4 165217 2688 840 14 1 994 978 016 014
159 159 25 1327 5 165317 2748 900 15 1 992 978 014 012
186 187 27 1433
6 165417 2808 960 16 1 992 974 018 016
21 211 24 1274 7 165517 2868 1020 17 1 998 980 018 016
237 238 27 1433
8 165617 2928 1080 18 1 998 980 018 016
263 264 26 1380 9 165717 2988 1140 19 1 998 980 018 016
29 291 27 1433
10 165817 3048 1200 20 1 1000 982 018 016 015 315 316 25 1327 13796
0 165917 3108 1200 20
992 962
002 345 346
613
1 170017 3168 1260 21 1 1044 1012 032 030
389 390 44 2335 2 170117 3228 1320 22 1 1046 1012 034 032
43 431 41 2176
3 170217 3288 1380 23 1 1046 1012 034 032
475 476 44 2328 4 170317 3348 1440 24 1 1046 1012 034 032
516 518 41 2176
5 170417 3408 1500 25 1 1046 1012 034 032
56 562 44 2335 6 170517 3468 1560 26 1 1050 1012 038 036
602 604 42 2229
7 170617 3528 1620 27 1 1046 1012 034 032
646 648 44 2335 8 170717 3588 1680 28 1 1046 1010 036 034
688 690 42 2229
9 170817 3648 1740 29 1 1044 1006 038 036
73 732 42 2229
10 170917 3708 1800 30 1 1040 1006 034 032 032 773 775 43 2282 22628
0 171017 3768 1800 30
1038 988
002 819 821
787
1 171117 3828 1860 31 1 1020 974 046 044
874 877 55 2918
2 171217 3888 1920 32 1 1018 966 052 050
928 931 54 2865
3 171317 3948 1980 33 1 1014 960 054 052
983 986 55 2918
4 171417 4008 2040 34 1 1014 954 060 058
1039 1042 56 2972
5 171517 4068 2100 35 1 1012 946 066 064
1093 1096 54 2865
6 171617 4128 2160 36 1 1010 930 080 078
1147 1150 54 2865
7 171717 4188 2220 37 1 1010 920 090 088
1202 1206 55 2918
8 171817 4248 2280 38 1 1012 904 108 106
1256 1260 54 2865
9 171917 4308 2340 39 1 1012 882 130 128
1311 1315 55 2918
10 172017 4368 2400 40 1 1018 850 168 166 083 1367 1371 56 2972 29078
0 172117 4428 2400 40
1098 750
040 1422 1426
419
1 172217 4488 2460 41 1 1522 586 936 934
1482 1486 60 3184
103
2 172317 4548 2520 42 1 1746 278 1468 1466
1542 1547 60 3184 3 172417 4608 2580 43 1 2720 060 2660 2658
1597 1602 58 3068
a The system was running with no permeate flux in the first 12 minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to twelfth minute (No1-10 in the spreadsheet) were averaged into the mean TMP for calibration by
deducting the value
b The data (one minute) at the beginning of each filtration process (increased flux) was disregarded
c Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2
)
d TMP and flux were averaged in each cycle and plotted in the plot
104
Appendix C Example of Data Processing for a Multi-cycle
Membrane Filtration Experiment
Membrane
Effective filtration surface area 000113 m2
Effective diameter of filtration cell 0038 m
Material polyvinylidene fluoride (PVDF)
Pore size 022 microm
Operation condition
Viscosity 000066 kg m-1 s-1
Specific gravity of water 099206 g mL-1
Nominal cross-flow velocity 37 m s-1
Flow rate 708 mLmin
Sample type Cintas Laundry wastewater
Volume 4 L
pH 11plusmn03
Temperature 40plusmn2 degC
Sample Type 85 ppm (CN) with Epi-DMA
105
Table C2 Data processing for multi-cycle membrane experiments
No Real
sampling Time
Cumul
ated filtration time
(sec)
Calibr
ated filtration time-A
(sec)
Calibr
ated filtration time-B
(min)
Calibra
ted filtration time-C (hr)
Unit
filtration time (min)
Feed
pressure (psi)
Perme
ate pressure (psi)
TM
P (psi)
Calibr
ated TMP (psi)
Mea
n TMP (psi)
TM
P at point (psi)
Perme
ate weight (g)
Permeat
e volume (mL) -Accumulated-
Unit
permeate volume (mL)
Specifi
c permeate (L m
-2)
c
Perme
ate flux (L m
-2 hr
-
1)
d
Mean
permeate flux (L m
-2 hr
-
1)
1 162505 273
1102 1050 052 002
0 2 162606 333
1122 1070 052 002
0
3 162705 393
1040 988 052 002
0 4 162806 453
1026 980 046 -004
0
5 162905 513
1058 1010 048 -002
0 6 163006 573
1030 980 050 000
0
57 Lmh
7 163105 633 1046 998 048 -002 050a 0 3 plusmn
0 163206 693 0 0 1056 998 058 008 0 0 00
1 163305 753 60 1 002 1 1078 1020 058 008 12 12 12 11 640
2 163406 813 120 2 003 1 1032 974 058 008
22 22 10 20 533 3 163505 873 180 3 005 1 1038 982 056 006
32 32 10 28 533
4 163606 933 240 4 007 1 1046 992 054 004
43 43 11 38 587 5 163706 993 300 5 008 1 1068 1006 062 012 008 012 53 53 10 47 533 565
6 163806 1053 360 6 010 1 1076 1018 058 008
64 65 11 57 587 7 163906 1113 420 7 012 1 1088 1030 058 008
74 75 10 66 533
8 164006 1173 480 8 013 1 1026 968 058 008
85 86 11 76 587 9 164106 1233 540 9 015 1 1052 994 058 008
96 97 11 85 587
10 164206 1293 600 10 017 1 1056 998 058 008 008 008 106 107 10 94 533 565
11 164306 1353 660 11 018 1 1030 978 052 002
117 118 11 104 587 12 164406 1413 720 12 020 1 1032 974 058 008
128 129 11 114 587
13 164506 1473 780 13 022 1 1044 986 058 008
138 139 10 123 533 14 164606 1533 840 14 023 1 1050 994 056 006
149 150 11 132 587
15 164706 1593 900 15 025 1 1052 994 058 008 007 008 159 160 10 141 533 565
106
16b 165350 1997 1304 16 0 1 994 940 058 008 0 164 165 155
17 165450 2057 1364 17 028 1 992 934 058 008 174 175 10 155 533
18 165550 2117 1424 18 030 1 1000 940 060 010
184 185 10 164 533 19 165650 2177 1484 19 032 1 1010 952 058 008
195 197 11 173 587
20 165750 2237 1544 20 033 1 1020 962 058 008
205 207 10 182 533 21 165850 2297 1604 21 035 1 1026 966 060 010 009 010 216 218 11 192 587 555
22 165950 2357 1664 22 037 1 1032 972 060 010
227 229 11 202 587 23 170050 2417 1724 23 038 1 1040 980 060 010
237 239 10 211 533
24 170150 2477 1784 24 040 1 1040 982 058 008
248 250 11 220 587 25 170250 2537 1844 25 042 1 1038 978 060 010
259 261 11 230 587
26 170350 2597 1904 26 043 1 1040 980 060 010 010 010 269 271 10 239 533 565
27 170450 2657 1964 27 045 1 1044 986 058 008
279 281 10 248 533 28 170550 2717 2024 28 047 1 1046 988 058 008
29 292 11 258 587
29 170650 2777 2084 29 048 1 1052 994 058 008
301 303 11 268 587 30 170750 2837 2144 30 050 1 1062 1000 062 012
312 314 11 277 587
31 170850 2897 2204 31 052 1 1058 994 064 014 010 014 322 325 10 286 533 565
32 171556 3324 2631 32 1 1006 948 062 012 0 33 333 08 303
33 171656 3384 2691 33 055 1 1004 942 062 012 341 344 11 303 587
34 171756 3444 2751 34 057 1 1014 954 060 010
351 354 10 312 533 35 171856 3504 2811 35 058 1 1030 968 062 012
363 366 12 323 640
36 171956 3564 2871 36 060 1 1038 978 060 010
373 376 10 332 533 37 172056 3624 2931 37 062 1 1046 986 060 010 011 010 383 386 10 340 533 565
38 172156 3684 2991 38 063 1 1052 988 064 014
394 397 11 350 587 39 172256 3744 3051 39 065 1 1058 994 064 014
405 408 11 360 587
40 172356 3804 3111 40 067 1 1062 998 064 014
416 419 11 370 587 41 172456 3864 3171 41 068 1 1070 1006 064 014
427 430 11 380 587
42 172556 3924 3231 42 070 1 1082 1014 068 018 015 018 437 440 10 388 533 576
43 172656 3984 3291 43 072 1 1088 1024 064 014
448 452 11 398 587 44 172756 4044 3351 44 073 1 1098 1032 066 016
459 463 11 408 587
45 172856 4104 3411 45 075 1 1020 960 060 010
469 473 10 417 533 46 172956 4164 3471 46 077 1 1026 966 060 010
48 484 11 427 587
47 173056 4224 3531 47 078 1 1046 982 064 014 013 014 491 495 11 436 587 576
48 173714 4602 3909 48 1 1020 960 060 010 496 500 450
107
49 173815 4662 3969 49 082 1 1020 960 060 010 506 510 10 450 533
50 173914 4722 4029 50 083 1 1024 960 064 014
517 521 11 460 587 51 174015 4782 4089 51 085 1 1024 960 064 014
528 532 11 469 587
52 174114 4842 4149 52 087 1 1024 962 062 012
538 542 10 478 533 53 174215 4902 4209 53 088 1 1026 962 064 014 013 014 549 553 11 488 587 565
54 174314 4962 4269 54 090 1 1030 962 068 018
56 564 11 498 587 55 174415 5022 4329 55 092 1 1024 960 064 014
57 575 10 507 533
56 174515 5082 4389 56 093 1 1024 960 064 014
58 585 10 516 533 57 174615 5142 4449 57 095 1 1024 960 064 014
591 596 11 525 587
58 174715 5202 4509 58 097 1 1026 960 066 016 015 016 602 607 11 535 587 565
59 174815 5262 4569 59 098 1 1030 966 064 014
613 618 11 545 587 60 174915 5322 4629 60 100 1 1030 968 062 012
623 628 10 554 533
61 175015 5382 4689 61 102 1 1032 968 064 014
634 639 11 564 587 62 175115 5442 4749 62 103 1 1032 972 060 010
645 650 11 573 587
63 175215 5502 4809 63 105 1 1038 974 064 014 013 014 655 660 10 582 533 565
64 175715 5803 5110 64 1 1014 962 066 016 659 664 595
65 175816 5863 5170 65 108 1 1032 966 066 016 669 674 10 595 533 5599
66 175915 5923 5230 66 110 1 1038 972 066 016
681 686 12 605 640 67 180016 5983 5290 67 112 1 1044 980 064 014
691 697 10 614 533
68 180115 6043 5350 68 113 1 1050 986 064 014
701 707 10 623 533 69 180216 6103 5410 69 115 1 1052 988 064 014 015 014 712 718 11 633 587 565
70 180315 6163 5470 70 117 1 1058 994 064 014
723 729 11 643 587 71 180416 6223 5530 71 118 1 1058 994 064 014
733 739 10 651 533
72 180516 6283 5590 72 120 1 1058 994 064 014
744 750 11 661 587 73 180616 6343 5650 73 122 1 1014 954 060 010
755 761 11 671 587
74 180716 6403 5710 74 123 1 1006 942 064 014 013 014 766 772 11 681 587 576
75 180816 6463 5770 75 125 1 986 924 062 012
777 783 11 691 587 76 180916 6523 5830 76 127 1 1004 936 068 018
787 793 10 699 533
77 181016 6583 5890 77 128 1 1004 936 068 018
798 804 11 709 587 78 181116 6643 5950 78 130 1 1000 934 066 016
809 815 11 719 587
79 181216 6703 6010 79 132 1 988 922 066 016 016 016 819 826 10 728 533 565
80 181814 7062 6369 80 1 1010 946 064 014 823 830 741
81 181914 7122 6429 81 135 1 978 914 064 014 834 841 11 741 587
108
82 182014 7182 6489 82 137 1 966 902 064 014
844 851 10 750 533 83 182114 7242 6549 83 138 1 1006 940 066 016
854 861 10 759 533
84 182214 7302 6609 84 140 1 1004 934 070 020
866 873 12 770 640 85 182314 7362 6669 85 142 1 1000 934 066 016 016 016 876 883 10 779 533 565
86 182414 7422 6729 86 143 1 1000 934 066 016
887 894 11 788 587 87 182514 7482 6789 87 145 1 998 934 064 014
897 904 10 797 533
88 182614 7542 6849 88 147 1 1000 934 066 016
908 915 11 807 587 89 182714 7602 6909 89 148 1 998 930 068 018
918 925 10 816 533
90 182814 7662 6969 90 150 1 1000 934 066 016 016 016 929 936 11 826 587 565
91 182914 7722 7029 91 152 1 998 934 064 014
94 948 11 835 587 92 183014 7782 7089 92 153 1 998 930 068 018
951 959 11 845 587
93 183114 7842 7149 93 155 1 998 930 068 018
961 969 10 854 533 94 183214 7902 7209 94 157 1 998 930 068 018
972 980 11 864 587
95 183314 7962 7269 95 158 1 998 930 068 018 017 018 983 991 11 874 587 576
96 184126 8454 7761 96 1 1050 982 070 020 986 994 886
97 184226 8514 7821 97 162 1 1052 982 070 020 997 1005 11 886 587
98 184326 8574 7881 98 163 1 1052 986 066 016
1007 1015 10 895 533 99 184426 8634 7941 99 165 1 1056 988 068 018
1018 1026 11 905 587
100 184526 8694 8001 100 167 1 1056 988 068 018
1029 1037 11 915 587 101 184626 8754 8061 101 168 1 1058 992 066 016 018 016 1039 1047 10 923 533 565
102 184726 8814 8121 102 170 1 1026 960 066 016
105 1058 11 933 587 103 184826 8874 8181 103 172 1 1012 946 066 016
1061 1069 11 943 587
104 184926 8934 8241 104 173 1 1006 940 066 016
1071 1080 10 952 533 105 185026 8994 8301 105 175 1 1004 934 070 020
1082 1091 11 962 587
106 185126 9054 8361 106 177 1 1004 936 068 018 017 018 1093 1102 11 971 587 576
107 185226 9114 8421 107 178 1 1004 936 068 018
1104 1113 11 981 587 108 185326 9174 8481 108 180 1 1004 934 070 020
1114 1123 10 990 533
109 185426 9234 8541 109 182 1 1004 936 068 018
1125 1134 11 1000 587 110 185526 9294 8601 110 183 1 1004 934 070 020
1135 1144 10 1009 533
111 185626 9354 8661 111 185 1 1006 940 066 016 019 016 1147 1156 12 1019 640 576
112 190429 9836 9143 112 1 1014 946 068 018 1158 1167 1038
113 190529 9896 9203 113 188 1 1014 946 068 018 1168 1177 10 1038 533
114 190629 9956 9263 114 190 1 1020 948 072 022
1179 1188 11 1048 587
109
115 190729 10016 9323 115 192 1 1024 954 070 020
1189 1199 10 1057 533 116 190829 10076 9383 116 193 1 1026 954 072 022
120 1210 11 1067 587
117 190929 10136 9443 117 195 1 1030 956 074 024 021 024 1211 1221 11 1076 587 565
118 191029 10196 9503 118 197 1 1030 960 070 020
1221 1231 10 1085 533 119 191129 10256 9563 119 198 1 1032 966 066 016
1232 1242 11 1095 587
120 191229 10316 9623 120 200 1 1038 968 070 020
1243 1253 11 1105 587 121 191329 10376 9683 121 202 1 1096 1024 072 022
1253 1263 10 1114 533
122 191429 10437 9744 122 203 1 1098 1026 072 022 020 022 1264 1274 11 1123 587 565
123 191529 10496 9803 123 205 1 1098 1026 072 022
1275 1285 11 1133 587 124 191629 10557 9864 124 207 1 974 910 064 014
1286 1296 11 1143 587
125 191729 10616 9923 125 208 1 928 866 062 012
1297 1307 11 1153 587 126 191829 10677 9984 126 210 1 982 910 072 022
1307 1317 10 1162 533
127 191929 10736 10043 127 212 1 1020 948 072 022 019 022 1317 1328 10 1171 533 565 a The system was running with no permeate flux in the first ten minutes to calibrate TMP The data collected in the first two minutes was
disregarded The TMP from the third to ninth minute (No1-7 in the spreadsheet) were averaged into the mean TMP for calibration by deducting
the value
b The data (one minute) between each cycle was disregarded
c Specific permeate was obtained by accumulated permeate volume divided by effective filtration area (00013 m
2 in this situation)
d Permeate flux (L m
-2 hr
-1) J= ∆V ∆tA) where ∆V=unit permeate volume L ∆t=unit permeate time hr A= membrane effective
filtration area (m-2)
110
Appendix D Images of SWRS Components and Hose Connection
Figure D1 SWRS components a) diverter box b) RO GAC filter UV light and chemical
injection pump controller c) MF d) RO vessels
a)
c)
b)
d)
111
Figure D2 Laundry water inlet connections a) sump and sump pump b) outlet of the sump
pump from Laundry Building c) hose connection to two 3K bladders d) 3K bladders and
SWRS unit
a)
c)
b)
d)
112
Appendix E Water Quality During SWRS Operation
Table E1 Water quality changes by coagulation MF RO and finished water
Sample position Raw Water
After Coagulation
MF Feed
MF Permeate
RO Filtrate
Finished Water
pH 1044 1059 106 1042 1049 94
Zeta potential mV -272 512 385 -466 -117 -118
-265 527 395 -222 241 -193
-254 465 393 -168 -209 -0566
-293 491 372 -142 003 319
Average mV -271 50 39 -25 -02 -01
STD mV 16 03 01 15 19 23
Turbidity NTU 892 417 423 046 019 024
87 417 241 045 021 02
Average NTU 88 42 33 0 0 0
STD NTU 2 0 13 0 0 0
Residual AVE 100 47 38 1 0 0
STD 35 18 164 18 18 18
COD mgL 546 263 275 134 9 2
Dilution times 1 546 263 275 134 9 2
Residual AVE 100 48 50 25 2 0
TP mg PO43-
L 022 025 024 01 01 008
Dilution times 50 11 125 12 5 5 4
Residual AVE 100 114 109 45 45 36
113
Table E2 Water quality changes by MF in SWRS operation (1)
Sample position MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate MF Feed MF Permeate
Date 20121214 20121214 20121214 20121214 20121215 20121215 20121216 20121216
Time 1220 PM 1220 PM 1250 PM 1250 PM 1240 PM 1240 PM 950 AM 950 AM
Bladder 2 2 2 2 1 1 1 1
pH 1047 94 1053 963 936 881 1185 1118
Zeta potential mV 0177 -119 0136 -149 -798 -181 -211 -989
-211 -843 -268 -145 -884 -213 -215 -17
-426 -792 -384 -168 -102 -196 -213 -164
-355 -106 -363 -171 -922 -198 -197 -212
Average mV -24 -70 -25 -158 -91 -197 -209 -161
STD mV 20 41 18 13 09 13 08 47
Turbidity NTU 354 198 346 197 215 114 790 121
345 193 357 2 205 121 798 122
Average NTU 35 2 35 2 21 1 794 12
STD NTU 1 0 1 0 1 0 6 0
Residual AVE 6 6 6 2
STD 19 23 36 07
COD mgL 255 61 261 84 115 44 1466 544
Dilution times 1 255 61 261 84 115 44 1466 544
Residual AVE 24 32 38 37
TP mg PO43-
L 1 058 1 055 1 087 6 374
Dilution times 5 5 29 5 275 1 8 29 187
Residual AVE 58 58 91 65
114
Table E3 Water quality changes by MF in SWRS operation (2)
Sample position Raw
After Coagulation Bladder 1 MF Feed MF Permeate Raw MF Feed MF Permeate
Date 20121219 20121219 20121219 20121219 20121220 20121220 20121220
Time 1140 AM 129 PM 130 PM 130 PM 430PM 1200 PM 1200 PM
Bladder 1 1 1 1 2 2 2
pH 1085 1112 1112 1115 1041 1033 98
Zeta potential mV -107 -122 -102 -106 43 293 -607
-129 -101 -113 -122 412 277 -562
-135 -135 -119 -134 392 303 -687
-146 -144 -112 -128 399 073 -529
Average mV -129 -126 -112 -123 41 24 -60
STD mV 16 19 07 12 02 11 07
Turbidity NTU 192 175 176 254 816 176 864
195 180 176 255 817 176 852
Average NTU 194 178 176 25 82 18 9
STD NTU 2 4 0 0 0 0 0
Residual AVE 92 91 13 22 11
STD 29 11 11 01 02
COD mgL 454 430 403 917 170 141 141
Dilution times 1 454 430 403 917 170 141 141
Residual AVE 95 89 202 83 83
TP mg PO4
3-
L 4 318 319 789 5 241 235
Dilution times 5 22 159 1595 3945 27 1205 1175
Residual AVE 73 74 182 45 44
115
Table E4 Water quality changes by MF in SWRS operation (3)
Sample position
Raw in Bladder 1
After coagulation in
bladder 1 MF Feed MF
Permeate Raw MF Feed MF
Permeate MF Feed MF
Permeate
Date 20121220 20121220 20121220 20121220 20121221 20121221 20121221 20121222 20121222
Time 1230 PM 220 PM 220 PM 220 PM 340 PM 340 PM 1240 PM 1240 PM
Bladder 1 1 1 1 1 1 1 1 1
pH 1055 1066 107 1047 10 1007 1006 1093 1061
Zeta potential mV -294 -132 -116 -117 -177 -0502 -00327 -25 -232
-328 -15 -129 -177 -179 -35 -511 -277 -243
-32 -164 -134 -206 -171 -269 -375 -28 -235
-303 -175 -132 -175 -158 -321 -167 -279 -278
Average mV -311 -155 -128 -169 -171 -25 -26 -272 -247
STD mV 16 19 08 37 09 14 22 14 21
Turbidity NTU 849 160 152 83 532 313 119 833 374
867 161 151 799 512 306 123 784 348
Average NTU 86 161 152 8 52 31 1 81 36
STD NTU 1 1 1 0 1 0 0 3 2
Residual AVE 187 177 9 59 2 45
STD 23 23 17 37 28 66
COD mgL 325 333 345 173 221 168 147 239 151
Dilution times 1 325 333 345 173 221 168 147 239 151
Residual AVE 102 106 53 76 67 63
TP mg PO4
3-L 6 595 593 228 1 124 072 7 41
Dilution times 5 30 2975 2965 114 7 62 36 36 205
Residual AVE 99 99 38 93 54 56
116
Appendix F SWRS Backwash Strategy without Starting the
High Pressure Pump
In order to operate SWRS without the high pressure components (high pressure pump
RO GAC filter UV light and post chlorination) start-up the following procedures were
carefully designed to keep the water only go through the first two treatment sections (pre-
filtration and MF) as well as conducting backwashing during operation
Low pressure start-up procedures
1 In the start-up screen go through the low pressure start
2 When the system is in the ldquotan fillingrdquo stage the last stage in low pressure start-
up) open the manual valve below the recycling tank
3 Then the water in the recycling tank is drained into the waste tank
4 Watch the water level in recycling tank from the screen and keep the water level
constant below the full- filled line by adjusting the value
5 The system will be in low pressure start-up status until the recycling tank is filled
Manual backwash
Before the system start-up close the chlorine feed pump (CT-03) by turning the
ldquospeedrdquo to ldquo0rdquo
Close the drainage manual valve below the recycling tank then the water level in
recycling tank goes up
Change the system to ldquotemporary shutdownrdquo in the main screen
The unit will automatically fill the recycling tank and go through the following
processes
Pre-Filter Flush
Micro-filter Flush
Backwash
Once backwash complete the screen shows micro-filter is in a 15 min chlorine
soa process Because this process is going to be in ldquochlorine soa rdquo status forever
shut down the system by turning off the system switch
Restart the system and go through the low pressure start-up procedures as listed
before
117
Appendix G RO Fouling Report
Table F1 SWRS data of all treatment units with tap water (normal operation) during
the first 10 min operation with laundry water and after 30 min operation with laundry
water (RO scaling)
Main Screen Clean Water
First 10min operation with laundry Water
After 30 min operation of laundry water
Output (gpm) 81plusmn03 8 58
Conductivity (microscm) 172 418 116
Pre-filter
Feed (psi) 55-60 56 24
Permeate (psi) 15 1371 11
MF
Flow Rate (gpm) 1047 994 800
TMP (psi) 483 458 320
RO
Feed Flow rate (gpm) 28-30 2985 1673
Permeate rate (gpm)
Feed pressure (psi)
78-84
193
8
1295
53
29708
Permeate Pressure (psi)
CIT-201 (Conductivity)a 2142
3370
1958
NAb
994
3313
CIT-501 (Conductivity)a 172 NAb 118 a The unit of conductivity could be microScm (unidentified) Data was not captured during test
118
Table F2 SWRS data on the tap water after RO scaling
a The unit of conductivity could be microScm (unidentified)
Main Screen 10min after start 1 hour after start
Output 35 26
Conductivity 30 30
Pre-filter Feed 56 25
Permeate 15 11
MF
Flow Rate 1030 83
TMP 450 3
RO Permeate rate 35 26
TMP 289 310
CIT-201 (Conductivity)a 1550 1550
CIT-501 (Conductivity)a 30 30