the effectiveness of the andco electrochemical treatment ... · the effectiveness of the andco...

Aucjust , 1 9 8 9 .

THE SFFECTiVZ;TXSS O F TI-IE ANDCO ELECTROCHEMICAL

TREATMENT PROCESS AND I T S APPLICATION IN TEXTILE

i'r AS T Eli A T E R TR E A TI~I EN T

A T h e s i s by Xarla Kaye Weinburcj

Georcjia I n s t i t u t e of T e c h n o l o G y

2 6 7 5 c u m D c r 1 ; in ci 9 3 i i w a \ ~

S l l i t t . 2 0 0 4 t i J n t a , C e o ~ 1 1 i I ' 3 3 0

F a c s i m i l e k0.i 3 I9 7777

-- I/

4

THE EFFECTIVENESS OF THE ANDCO ELECTROCHEMICAL TREATMENT PROCESS AND ITS APPLICATION IN TEXTILE

WASTEWATER TREATMENT

A THESIS Presented to

The Academic Faculty

Marla Kaye Weinberg

In Partial Fulfillment of the Requirements for the Degree

Master of Science

Georgia Institute of Technology August, 1989.

THE EFFECTIVENESS OF AN ELECTROCHEWCAL TREATMENT PROCESS AND I T S APPLICATIONS IN TEXTILE WASTEWATER

TREATMENT

Approved:

Wayne C. Tincher, cbntrmrn.

M L . cook

Edward Chian

DEDICATION

iii

ACKNOWLEDGEMENTS

With deepest admiration and heart felt appreciation, I

would like to thank parents Milton Weinberg and Shirley

Stinard for all their love and guidance. They have always

inspired me and supported my decisions, being there for me in

my greatest times of need. I would also like to thank my

sister, Lisa, for all her encouragement and help with my

thesis.

My thesis advisor, Dr. Wayne C . Tincher, has helped me

to recognize my own capabilities. His relentless striving for

perfection has fostered a conviction for perfection in all

aspects of my work. His patience and advice throughout my

years at Georgia Tech, as both an undergraduate and graduate

student, have been deeply appreciated.

I would also like to acknowledge the help of my defense

committee, Dr. Tincher, Dr. Fred L. Cook, and Dr. Edward Chian

for all of their time, help, and advice.

Tremendous thanks to my friends, Deann Smith, Dee Ling,

Ani1 Saraf, Katherine Edman, P. Dastoor, Rajeev Maholtra and

Sukasem Tejatanalert for their unmatched support and

assistance with my thesis.

Finally, I would like to send my deepest thanks to Andco

Environmental Processes, Inc. of Amherst, NY for coordinating

iv

this study and providing a pilot unit for the experimentation.

Without their cooperation, assistance and advice this project

would not have been possible. Special thanks to Mike

Lassingher and Kevin Uhrich for their instruction on the

operation and use of the Andco pilot unit.

TABLE OF CONTENTS Pase

DEDICATION ii ............................................. iii

LIST OF TABLES ......................................... vi

LIST OF ILLUSTRATIONS .................................. X

S.Y ................................................ xii

Chapter

I . Introduction and Literature Review ............ 1

The Textile Industry .......................... 2 Wastewater Characterization ................... 4 Current Treatment Technologies ................ 11 Electrochemical Wastewater Treatment .......... 30 The Andco Treatment Process ................... 45

I1 . Research Objective and Experimental Details ... 61

Experimental Methods and Procedures ........... 61 Analytical Testing Procedures. Methods and Equipment ..................................... 67 Color Removal Study ........................... 77 Dyebath Water Reuse Study ..................... 79 Color Measurement Theory ...................... 92

I11 . Results and Discussion ........................ 105

Chemical Oxygen Demand Reduction .............. 105 Color Removal Results ......................... 119 Treated Djebath Water Rewe Results ........... 139 A Study of the Color Removal Process .......... 148 Cost Analysis ................................. 162

IV . Conclusions and Recommendations ............... 167

REFERENCES ............................................. 210

vi

Table

1-1.

1-2.

1-3.

1-4.

1-5.

1-6.

1-7.

1-8.

1-9.

1-10.

3-1.

3-2.

3-3.

LIST OF TABLES

.. Pase

EPA historical averages of wastewater 7 composition for various textile subindustries.

Percent contribution of various chemicals to 8 textile wastewater

EPA average effluent limits set for textile mills.

13

Dalton Riverbend Wastewater Treatment Plant 14 effluent limitations set for local industries including textile mills.

Electrochemical treatment BOD reduction. 50

Electrochemical treatment COD reduction. 51

COD reduction after electrochemical treatment. 53

Electrochemical treatment color removal. 56

Absorbance values before and after electro- 58 chemical treatment with percent reduction of absorbance.

Heavy metal removal with increasing levels of 59 electrochemically generated iron.

COD values and percent removal values for 107 Stainblocker Formulation l1Al1 at 0.6 g/1 and 1.0 g/1 sample concentrations with increasing iron addition.

COD values and percent removal values for'. 108 Stainblocker Formulation ltBl1 at 0.6 g/1 and 1.0 g/1 sample concentrations with increasing iron addition.

COD values and percent removal values for Stainblocker Formulation llC1l at 0.6 g/1 and 1.0 g/1 sample concentrations with increasing iron addition.

110

3-4.

3-5.

3-6.

3-7.

3-8.

3-9.

3-10.

3-11.

3-12.

3-13.

3-14.

COD values and percent removal values for Stainblocker Formulation at 0.6 g/1 and 1.0 g/1 sample concentrations with increasing iron addition. *Denotes sample in which-no polymer was used to achieve a floc.

v i i

1 1 2

COD values and percent removal values for 113 Irgalev A, an auxiliary chemical, at 0.6 g/1 and 0.8 g/1 sample concentrations with increasing iron addition.

COD values and percent removal values for 114 Guar Gum, an auxiliary chemical, at 0.3g/l sample concentration with increasing iron addition.

COD values for distilled water blanks treated with the Andco Process, and the corresponding polymer quantities required to produce a floc.

Average peak height, total carbon and percent removal values for Stainblocker Formulation IIDtl at 0.6 g/1 and 1.0 g/1 sample concentrations with increasing iron. * Denotes samples in which no polymer was used to achieve a floc.

COD values and percent removal for the acid dye mixture at 25 (mg/l) and 50 (mg/l) sample concentrations with increasing iron addition.

Required polymer (ml), COD values and percent removal values for A.R. 361 dye at 2 5 (mg/l) and 50 (mg/l) sample concentrations with increasing iron addition.

Required polymer (ml), COD values and percent removal values for Procion Blue MS-2G dye at 2 5 (mg/l) and 50 (mg/l) sample concentrations with increasing iron addition.

Average peak height and total carbon values A) before iron blank subtraction, B) after iron blank subtraction, for the acid dye mixture at 25 (mg/l) sample concentrations.

Average peak height and total carbon values A) before iron blank subtraction B) after iron blank subtraction, for A.B. 4 0 25 (mg/l) sample concentration.

Average peak height and total carbon values for the distilled water iron blanks.

116

118

1 2 1

1 2 2

1 2 3

125

126

1 2 7

viii

3-15.

3-16.

3-17.

3-18.

3-19.

3-20.

3-21.

3-22.

3-23.

3-24.

3-25.

3-26.

3-27.

Absorbance values for distilled water treated 130 with the Andco Process. The absorbance values represent the color contribution of the iron.

Acid dye mixture percent reduction values for 135 15 (mg/l) and 25 (mg/l) samples with increasing iron addition A) before iron color absorbance subtraction B) after iron color absorbance subtraction. * Represents percent increase in absorbance.

Corresponding color reduction percent for the 136 acid dye mixture at 25 (mg/l) and 50 (mg/l) sample concentrations with increasing iron addition.

Absorbance and percent color reduction values for A.B. 40 25 (mg/l) sample A) before iron color absorbance subtraction B) after iron color absorbance subtraction.

137

Absorbance with percent reduction values for 138 Procion Blue MX-2G at 25 (mg/l) and 50 (mg/l) sample concentrations.

CIE LAB color matching for A.B. 277 dyeing #1 141 and A.B.277/A.R.361 purple dyeing #l.

CIE LAB color matching values for A. B. 277 142 dyeing #2. ST = Stainblocker/auxiliary spiked sample.

CIE LAB color matching values for A. R. 361 14 3 dyeing #l. ST = Stainblocker spiked sample.

CIE LAB color matching values for A. R. 361 145 dyeing #2. ST = Stainblocker spiked sample.

CIE LAB color matching values for Procion Red 146 dyeing #l.

Percent change in absorbance for Acid Blue 151 277 standards and treated samples at selected wavelengths.

Percent change in absorbance for FD&C Food 154 Yellow #5 standards and treated samples at selected wavelengths.

Percent change in absorbance for FD&C Food 157 Blue #2 standards and treated samples at selected wavelengths.

ix

3-28. Percent change in absorbance for Azobenzene 159 standards and treated samples at selected wavelengths.

3-29. Percent change in absorbance f o r Azobenz-ene 160 34 mg/L degraded with sodium hydrosulfite at se1ecte.q wavelengths and absorbances for dilute Aniline.

X

LIST OF ILLUSTRATIONS

,

Fisure

1-1.

1-2.

1-3.

1-4.

1-5.

1-6.

1-7.

1-8.

1-9.

1-10.

1-11.

1-12.

1-13.

1-14.

1-15.

1-16.

1-17.

Number of mills using various degrees of wastewater treatment of 1092 responding mills.

Chemicals used in dyeing and finishing.

Main types of dyes, their main use and associated chemicals.

Origin points of effluent wastewater from various textile processes.

An anionic polyacrylamide coagulation polymer.

Combinations of water treatment processes used most frequently in industry.

Total organic carbon vs. ozone dose to study dye destruction of Acid Blue 40 .

Schematic representation of (A) a cation exchange resin and (B) an anion exchange resin.

Useful ranges of separation processes.

Schematic diagram of a bipolar pump cell.

Schematic diagram of the Chemelec cell.

Schematic diagram of the ECO cell.

Schematic diagram of the multicathode cell.

Schematic diagram of the Swiss-roll cell.

Schematic diagram of the porous flow- through cell.

Schematic diagram of the RETEC cell.

Pase

3

5

6

10

21

23

26

27

29

33 ’

35

36

38

39

41

42

Schematic diagram of the fluidized bed c e l l . 43

xi

1-18.

1-19.

1-20.

1-21.

2-1.

2-2.

2-3.

2-4.

2-5.

2-6.

3-1.

3-30

3-31

Schematic diagram of the Andco Electro- chemical Treatment Cell.

Solubility limits of some common metal ions.

Electrochemical treatment color removal from red reactive dye mixture.

Electrochemical treatment color removal from reactive dye mixture.

Sample calculations for electrochemical iron addition.

The Andco vlM1l Cell pilot unit.

Schematic of COD test apparatus.

Schematic of an ACS Spectro Sensor I1 Spectrophotometer.

CIE LAB 1976 equations used to quantify sample differences. D = Difference.

Structures for (A) FDtC Yellow # 5 , (B) FD&C Blue #2, and (C) Azobenzene.

Absorbance vs. Iron Level (mg/l) at 610 nm for three different sets of treated distilled water blanks used to measure iron color contribution.

46

48

54

55

63

68

71

93

95

102

131

Annual and daily operating costs for a mill 163 treating 1.0 million gallons per day for different iron treatment levels. Iron sludge production is also given. Values rounded to the nearest-whole number and annual values represent 355 days.

Comparisions of A) Capital cost,B) Annual 164 Operating costC) Daily Operating cost and-.D) Annual Sludge Production for 1.0 million gallon/day treatment system with different treatment methods.

xi i

SUMMARY

The concern over the condition of the environment has

grown tremendously in recent years. Efficient use of

resources and energy is a growing trend that will hopefully

improve environmental conditions for future generations. The

commercial and industrial sectors have made great progress in

about the last 15 to 2 0 years by increasing their process

efficiency, and reducing process impacts to the environment.

Most industries use water at some point in their processes

producing wastewaters of various composition and

concentration. The textile industry is no exception, using

extremely large volumes of water for various aspects of

production. The wastewater is highly varied in composition

and concentration due to the wide range of processes involved

in fiber, yarn and fabric preparation and finishing processes.

Most large textile plants use some form of biochemical

treatment system such as oxidation ponds or aerobic sludge to

provide an intefmediate level of treatment. Most textile

wastewater is treated, sufficiently by these processes,

although color removal (from dyes) is usually pobr. This

research studies the effectiveness of an electrochemical

treatment process and its applications in textile wastewater

treatment.

xiii

The research has been divided into four primary studies

to determine: 1) If chemical oxygen demand is reduced for

stainblocker and auxiliary chemicals, 2) The extent of color

removal, 3 ) If simulated dyebath water can be reused in dyeing

after treatment, and 4 ) If dolor is removed solely by some

form of dye precipitation and/or by dye degradation /

alteration. Also, a cost analysis was performed to compare

the Andco Electrochemical Treatment Process with other

wastewater treatment processes.

The results of the study show that chemical oxygen demand

is reduced by 2 5 % to 100% depending on the chemical being

treated, its concentration and, the iron addition level being

used. Color removal was very good in the range of 70% to 100%

mostly depending on the concentration of dye in the test

solution. High iron addition levels (500-650 mg/l) were

required for COD removal of finishing chemicals, while color

removal was sufficient at much lower iron addition levels

(100-250 mg/l). The treated dyebath water reuse study

indicated that water reuse was not out of the question, but

would require full-scale dyebath testing to optimize the dyebath to achieve more conclusive results. The

experimentation studying the mechanism of dye removal

indicated that azo bond containing dyes were very susceptible

to destruction, as were those containing aliphatic carbon-

carbon double bonds. The results indicated that aromatic

amines were produced in the destruction process. Also,

xiv

to destruction as were those containing aliphatic carbon-

carbon double bonds. The results indicated that aromatic

amines were produced in the destruction process. Also,

anthraquinone dyes appeared to be removed primarily by some

form of precipitation as opposed to destruction.

The cost analysis showed that the Andco Electrochemical

Treatment Process is economically competitive with other

wastewater treatment processes having similar capabilities.

1

CHAPTER I

INTRQDUCTION AND LITERATURE REVIEW

Introduction

As technology approaches the beginning of the 21st

century, the world races to keep up with it. The 20th century

has been revolutionary as It The Age of Technology.1t However,

many problems still plague the world - nuclear weapons,

disease, hunger and, of course, the deteriorating state of the

environment. Perhaps the 21st century will bring a new age

and way of thinking - perhaps It The Age of Responsibility."

The responsibility of the planet's welfare, once left to

nature, has now been accepted by the people who inhabit it.

People are trying to make amends for the careless treatment

of the planet and its resources. This study addresses the

environmental problem of water pollution reduction. Specific

focus is placed on the reduction of textile industry

wastewater constituents using an electrochemical removal

process developed and patented by Andco Environmental

-

Processes, Inc. of Amherst, New York.

Research was conducted to evaluate the effectiveness of

the Andco Treatment Process in the following applications:

chemical oxygen demand (COD) reduction, color removal and

treated dyebath water reuse. Also, a fourth study was

2

conducted to determine if color removal was totally a

consequence of dye removal or some combination of removal and

chemical alteration. Finally, a cost comparison was prepared

to determine the economic acceptability ofthe Andco Treatment

Process compared with other water treatment systems.

Background information on the textile industry, current

treatment technologies (including other electrochemical

treatment technologies), and the Andco Treatment Process is

provided for reference and comparison.

The Textile Industrv

The textile industry encompasses a wide range of sub-

industries that produce textile products, textile processing

chemicals and specialty products. There are approximately

7,000 textile mills nationwide, 77% in the mid and south-

Atlantic regions, 10% in New England and 6% in the Pacific

region [I). Nationwide, the textile industry produces

approximately 50-75 billion dollars/year of products which are

shipped worldwide. Large digit figures are not limited to

sales only. The water consumption required to process such

huge quantities of textile products is approximately 3xi08

m3/yr [l] . But the massive amount of water required is not

always as great a concern as the ability to treat it. Textile

wastewater is highly varied in pollutant composition and

concentration making treatment of certain types of textile

wastewater very expensive and sometimes difficult.

I

3

a

a

t

z

W

4

Fortunately, a variety of treatment systems are available

which can successfully treat most combinations of textile

wastewater - each with its own advantages and disadvantages as will be discussed later in this chapter. Some mills do not

treat their wastewater. Many textile mills discharge to

local waterways or local POTWs with little or no treatment.

Of the 1,092 textile mills responding to a 1982 EPA survey,

it was found that 504 discharged to a POTW with no treatment.

Of those providing treatment, 289 discharged with preliminary

treatment while only 18 direct and one indirect discharger

used some type of advanced treatment as shown in Figure 1-1

111

Wastewater Characterization

As previously stated, the major problem involved in

treating textile wastewater is the varied composition of the

wastewater. Figure 1-2 shows the approximate categories of

chemicals used in dyeing and finishing processes [2]. Figure

1-3 shows specific dye types, their main use and other

auxiliary chemicals used with them respectively [2].

Recently, however, the use of chromium has decreased due to

EPA restrictions and more stringent regulations set by OSHA

(Occupational Safety and Health Agency) to protect workers.

Continuing, Table 1-1 shows the EPA historical averages of

wastewater composition for various textile subindustries

The values are expressed as Kg pollutant/KKG of product. Of

all the subindustries, the wool industry leads in the amount

5

Acids - i n o r g a n i c and o r g a n i c (e .g . fo rmic and a c e t i c )

Alkalis

Bleaches ( c h l o r i n e , hydrogen pe rox ide )

F l u o r e s c e n t s h i t e n i n g a g e n t s

Soaps and d e t e r g e n t s

Dye carriers and o t h e r a d d i t i v e s (e.g. o-phenyl phenol , benzo ic a c i d , phenyl methyl c a r b i n o l )

O i l s

S t a r c h o r s u b s t i t u t e (e.g. ca rboxymethy lce l lu lose )

Res ins

F i r e - , r o t , and w a t e r p r o o f i n g a g e n t s

P e s t i c i d e s

S i l i c a t e s

S u l p h i d e s

Var ious i n o r g a n i c sa l ts

Organic s o l v e n t s

Figure 1-2 Chemicals used in dyeing and finishing [ 2 ] .

. .

6

Tjpe of'dyc s l a in USC Associatcd p rwcss chemicals

Acid \Vool, n_vIon

Azoic Cotton

nasic Acylic

Direct Cotton, synthetics

Dispcrsc Polyester

Mordant \Vml

Kcaccivc Cotton, wool

Sulphur Cotton, synthctin

Vat cot ton, synthctics

Sulphun'c acid Acctic acid Sodium sulph3tc Surfactants

Metal salts Formaldehydc Sodium h5drosidc Sodium nitrire Acids

__

Acctic acid Softcning agcnt

Sodium salts Fixing agcnt hlctal salts (coppcr or chromatcr.)

Gamer Sodium hy d rosidc Sodium hxdrosulphitc

Chromium and other mctal salts Acctic acid Sodium sulphatc

Sodium chloridc Sodium hydrosidc Ethylcnc diaminc

Sodium sulphidc and othcr salts Acctic acid

Sodium hFdrosidc Sodium hFdrosulphitc and othcr salts. S u rf3ctanrs

Figure 1-3 Main types of dyes, their main use and associated chemicals [ 2 ] .

7

Table 1-1

Subcategory

EPA historical averages of wastewater composition f o r various textile subindustries Cll-

1.

2.

3.

4.

5 .

6.

7.

a.

9 .

Wool Scouring

Wool Finisbing

Low Uater Use Processing a. General Processing b . Water Jet Weaving

Woven Fabric Finishing a . Simple Processing b. Complex Processing c. Desiring

Knit Fabric Finishing a. Simple Processing b. Complex Processing c. Hosiery Products

Carpet Finisbing

Stock L Yarn Finisbiog

Nonvoven Hanufacturiog

Felted Fabric Processing

1830 6900 2703 580

150

380 120

300 350 405-

205 260 325

440

190

175

205

650

1060 180

900 1170 1260

765 835

1300

1190

685

2360

555

sc, i

220 I 25 #

60 65 80 45

160 7 0 -

60 95 so 50 80 100

65 20

4 0 25

80 . a 1 IS 30

I

0

I I

55 100 130

55 155 560

175

2$5

a

a

0

50

I I

49 180 146

108 107 62

130

172

d

* 575

a

0

R f l -

1000 500

U

390 760 450

690

5 i o

V

c ~~

I Insuff ic ient data t o report value.

fource: 308 Survey Data, Table V-11.

8

Table 1-2 Percent contribution of various chemicals to textile wastewater [ 4 ] .

Source

F i b e r F i n i s h .

Dyeing Chemicals Dyes S t a i n Blockers

Contribution

50-65% 25-35%

2-5% 5-25%

9

of conventional pollutants (BOD,, TSS) produced. The carpet

industry comes in close behind the wool industry producing

very high concentrations of nonconventional pollutants like

COD (chemical oGgen demand). Tincher reports that fiber

finish contributes the greatest amount to the COD level,

nearly 50-65% as shown in Table 1-2 ( 4 1 . Tincher also

explains that COD levels have risen recently due to the advent

of stainblocking agents. The increased use of stainblocking

chemicals, the growing use of jet dyeing, as well as, the

recent growth in the carpet industry are some of the main

facters which have resulted in an increase in water demand

from an average of 5.6 gallons per pound of carpet in 1980 to

6 . 2 gallons per pound in 1988 [ 4 ] . In addition, further

demands are placed on-treatment systems not only due to the

varied wastewater from subindustry to subindustry, but also

within each subindustry. Figure 1-4 shows an example within

given subindustries of the different wastewater producing

processes [2]. Usually, each process employs a unique set of

processing chemicals. In most cases the wastewater from each

process is mixed as it travels through piping systems to a

central exit pipe or sewer line. When the water leaves the

plant it must meet limits set by the EPA and local authorities

for direct (discharging to a waterway) and indirect

(discharging to a sewer) dischargers.

10

Synthetics

Cording Q

- Scouring

Fulling c;?

- E

rirE Scouring

L

Bleaching

F+ [q--]+ Mercer i z i n g

Knit cf7 Dyeing o n d I f in i sh ing I-- E

FE Dyeing ond f i n i s h i n g

Dyeing qE Scouring ond bleoching

IE Finishing

Figure 1-4 origin points .of effluent wastewater from various textile processes [ 2 ] .

11

Effluent Limitations

The textile industry until recently has been out of the

public eye and has received little attention concerning its

pollutant dischaege. However, recent media coverage of

chemical, petroleum, and environmentally related accidents

has lead to increased scrutiny oftextile wastewater effluents

and treatment systems [ 4 ] . Local POTWs are finding it more

difficult to treat the growing volumes of textile wastewater

along with higher COD levels. They are also beginning to find

it more and more difficult to meet their own effluent

limitations for water exiting the treatment plant. The

biological treatment systems used are also susceptible to

inhibition from textile process chemicals, Although POTWs

often fine or require a surcharge from companies discharging

excessive'volumes or wastewater over pollutant limits, they

still have a finite maximum of water they can treat. Also,

the public sector generally takes priority in that its water

must be handled first; the remainder of the POTW's capacity

can be used by industry. When this capacity is- reached the

responsibility to reduce volume and/or pollutant ccncentraticn

lies in the hands of the industry. In some cases industries

have coordinated their efforts with local POTWs by staggering

production periods to create a more even wastewater load on

the POTW. During the summer drought of 1988, Dalton Riverbend

Wastewater Treatment Plant coordinated a plan with local

industries where each was assigned a five days on two days off

12

production schedule - staggered against each other to lower water use and create a balance in f l o w over a seven day

period. The plan worked successfully to reduce the impact of

the drought for a l l parties [32]. The industries and their

materials suppliers have also worked to minimize waste at the

source by continually maximizing their processes and

reformulating chemical finishes to reduce pollutant content

and strength. By operating under such strategies, wastewater

treatment costs are generally reduced, not to mention the cost

savings associated with increased process efficiency and

materials utilization.

EPA effluent limits for the textile industry are given

in Table 1-3 [32]. The nonconventional pollutant, COD, and

the conventional pollutants, BOD and TSS have their limits

decided by local POTWs according to the EPA, which sets limits

on the other nonconventional pollutants as shown in Table 1-

3. The values given are average values which vary depending

on a company's size, water consumption, flow fluctuation,

location and position relative to other pollution souxces [I],

1301 The EPA has three main sets of regulations

corresponding to BCT, BAT and NSPS standards. The BCT - Best Control Technology standards given are the least stringent

followed by the BAT - Best Available Technology standards. The NSPS - New Source Performance Standards are the tightest standards placed on the textile industry. The previous terms

refer to the use of equipment and processes which provide

13

Table 1-3 EPA average effluent limits set for textile mills [32].

14

_.

Table 1-4 Dalton Riverbend Wastewater Treatment Plant effluent limitations set for local industries including textile mills [32].

15

necessary pollutant reduction to keep a process within the

given pollution limitations. Under such regulations, if a

company can afford and needs a given treatment system, then

the EPA requires'*.the acquisition of such technology. As

previously mentioned, local authorities may also have their

own limits and guidelines for wastewater discharge which may

be more stringent than EPA values. Table 1-4 shows

limitations set by the Dalton Riverbend Wastewater Treatment

Plant which treats large volumes of textile industry

wastewater [32]. These values are fairly representative of

treatment plants processing textile wastewater.

Current Treatment Technolosies

Before selecting a treatment system for a wastewater

stream, a thorough investigation should be made of all options

available, their respective efficiencies, disadvantages and

-

of course, the economics involved. The following section

contains summaries of long-standing treatment systems, as well

as, the latest high technology removal systems. Both

preliminary and intermediate systems are discussed, as well-

as advanced treatment systems.

Preliminary Treatment

Screeninq. Wastewater flows through a grid type screen

which may be stationary or rotating (for easier cleaning and

maintenance). Textile industry wastewater often requires some

type of screening to remove solid wastes such as fiber and

16

yarn masses which can clog pipes and j am equipment gears.

Also, much of the solid waste from carpet mills consists of

nylon fibers which are not readily biodegradable, so it is

best to screen out 'these materials before any wastewater exits

the plant [l], [2].

Neutralization. The wastewater stream is adjusted to pH

6-9 (the average pH range required by local POTWs) using NaOH,

Na,CO,, H2S0 , or by passing the flow over limestone

derivatives. Adjustment is required before the wastewater can

be released to a waterway to reduce impact to existing

biological systems which are very sensitive to pH changes.

Also, local POTWs cannot accept water out of the pH 6-9 range

because 'it will kill off or inhibit growth of their biological

treatmeht systems. Acidic waste from indirect dischargers is

the largest category requiring a neutralization process [l],

121, 1301.

Equalization. The practice of sanctioning all

wastewaters to a given holding tank or lagoon where the water

is allowed to mix and dilute. Thus, any heterogenous mixture

of pollutants becomes more uniformly mixed, and the overall

strength is decreased by dilution. Neutralization. may also

be combined with this phase of treatment. The final

wastewater is then easier to treat by more advanced methods

which are usually less efficient in processing unequalized

waste. There will also be reduced shock to biological

treatment systems if the water is to be released to a local

17

.POTW

Heat Exchanse. Large amounts of water are used at

elevated temperatures in many textile processes. Heated

wastewater emptied into a stream can have very adverse

effects; raising or lowering the temperature even 2-3OC can be

detrimental to most marine life by denaturing proteins and

enzymes, as well as, reducing the dissolved oxygen capacity

of the waterway. Higher temperatures cause increased

respiration in bacteria further reducing oxygen levels.

Warmer water also enhances algal growth which tends to kill

off other biological systems by depleting oxygen and blocking

out sunlight. To reduce biological temperature shock, the

water can be processed through a heat exchanger which can

recover some of -the heqt energy for reuse [l]., [30].

Sedimentation. Particulates, fiber waste and organic

Dissolved matter are allowed to settle out in a holding tank.

air floatation may be used to remove by-products of wool

processing like grease and oils. Lanolin is recovered from

the grease as a marketable item 111, [2].

Disinfection. In wastewater flows having a high natural

organic content such as wool or cotton processing waters, the

biological activity may be cite high. Chlorination may be

usedto reduce bacteria levels. Wastewater with high bacteria

levels can reduce the oxygen content and disrupt the bacterial

composition of the receiving stream [l], [ 2 ] , [30].

18

Intermediate Treatment

Treatment Lasoons. Also called oxidation or

stabilization ponds, treatment lagoons are generally shallow

ponds approximately 2 to 4 ft in depth. The ponds may be

aerated mechanically or simply by surface exposure to air.

The algae Chlorella pyrenoidosa also releases 0, during

photosynthesis which is used for biochemical oxidation of

waste products. Nutrients (nitrogen and phosphorous) are

usually required along with long residence times ranging from

3-8 days. Land requirements may be economically prohibitive

depending on the size of the lagoon required. Although BOD

is reduced, many toxic compounds are not reduced due to

biological inhibition, and color reduction is variable [I],

123, 131, ~273. Activated Sludse. May be carried out under aerobic or

anaerobic conditions. Aerobic sludge digestion is carried out

under vigorous aeration. Huge quantities of bacteria, as well

as, yeasts, molds and protozoa take part in breaking down

organics to highly oxidized products. Proteins and other

nitroger, compounds are broken down to amino acids and finally

to nitrates. Alcohols and organic acids are oxidized to .co,

and H,O, as are carbohydrates and fats. Many textile process

chemicals fall into the formentioned categories making them

easy targets for removal. Some chemicals like aromatic dyes

are not easily broken down by the biological systems in

-

19

activated sludge so color removal may be poor. Continuing, the

settling process involves small particals called floccules

which are formed as filamentous bacteria like Thiothrix and

Nocardia form networks among the waste aggregates and

microorganisms. Excess amounts of filamentous organisms may

cause bulking which leads to poor settling, The entire

process may take 4 to 8 hours with considerable removal of

- suspended solids and BOD ranging from 7 0 to 97 %. Extended

aeration may be needed for stronger or more complicated

wastestreams with 2 4 hour or longer retention times. Aerobic

digestion can also be combined with PAC (powdered activated

carbon). The carbon is added to the sludge to adsorb organic

compounds. Biological activity develops on the carbon as

microorganisms beg-in to feed on the adsorbed materials, The.

carbon is continually reactivated as the biological activity

reduces the organic content of the carbon allowing it to

maintain adsorption capacity. This combination of treatment

systems allows for better organic constituents removal.

Anaerobic sludge digestion is used to a lesser extent.

The wastewater is broken down to organic acids by facultative

bacteria like Enterobacter and Pseudomonas . The acids are

further degraded by anaerobes like Methanobacterium and

Methanococcus. The anaerobes degrade the acids to large amounts

of methane (60 - 70 % ) and carbon dioxide (20 - 30 % ) . The

methane can be recovered for heating and operating power.

20

Complete digestion may take 2 to 3 weeks or longer with the

final wastestream containing incompletely oxidized products

c11, [21, 133, r271

Chemical Coasulation. Lime, aluminum salts, ferric

chloride, ferric sulfate, or calcium ions are used as

coagulants to help settle out solids, Coagulation aids such

as synthetic polymers are used if needed to improve

flocculation and settling. Most polymers used in flocculation

have molecular weights greater than 200,000 and often up to

several million. Figure 1-5 [ 1 3 ] shows one monomer unit of

9 polyacrylamide anionic polymer. This polymer is closely

related to the polyacrylamide polymer used in the experiments

of this study, The x and y values represent the mole

fractions of each copolymer and n is the number of monomer

units. The x value is at least 5 0 % . The A- is an anion and

R is an alkyl group. This polymer is produced by American

Cyanamid Co. for raw water clarification. Alternatively, a

process described by American Color & Chemical Corp. [12]

causes precipitation of metals in metallized azo dyes by

addition of Fe" from finely divided iron (80 mesh) at 2% by

weight based on solution weight. Color reduction ranged from

a factor of 4 to 20. In general, coagulation processes reduce

BOD, COD, color, heavy metals and suspended solids. However,

color reduction depends on the dye class and dye process

employed. Many variables (pH, chemical addition/type) must

be controlled to achieve the best degree of coagulation and

2 1

. .

-CH,-CH I I I

- CH2 1

c=o NH

I

-

X

Figure 1-5 An anionic polyacrylamide coagulation polym*::- [ I 3 1 -

22

settling making this treatment option highly susceptible to

variation in degree of efficiency. Also, mixed wastewater is

difficult to treat as different wastes may require different

chemical coagulants. In addition, the final sediment is a

sludge which must be disposed of through a separate solid

waste system creating an additional cost 113, [2], [3], [12],

c131-

Advanced Treatment Systems

When stringent regulation levels must be met, or if water

recycling is desired, various combinations of preliminary,

intermediate and advanced treatment systems are employed.

Figure 1-6 shows a schematic of possible combinations that can

be used to attain reusable water [2]. The following are brief

descriptions of those asvanced treatment options available to

plants that need a polishing treatment system.

Granular Activated Carbon fGAC). Water is passed over

a bed of activated carbon on which organics and dyes adsorb.

The activated carbon adsorbs up to 1/3 of its weight in

contaminants before residual chemicals can be detected after

treatment. However, naturally occurring organics in water can

reduce GAC adsorption capacity according to Kavanaugh [31].

Also, high molecular weight and nonpolar compounds are most

effectively adsorbed: however, disperse dyes (a principal dye

type for polyester) adsorb poorly. When the adsorption

capacity is exhausted, the carbon must be replaced or

regenerated by furnace treatment or steam heat. GAC is an

23

Effluent I

F i g u r e 1-6

I C ) boloncing

sedimenlotion Sedimentof ion

lrcotmcnt

Oischorgc Oischorge

Comhi nations of w a t e r t r e a t m e n t processes LISP.^ most frequently in industry 121 -

24

expensive capital investment and if regeneration equipment is

used, the cost increases tremendously as can be seen in the

cost analysis section [l], [2], [ 3 ] , [ll]. -

Ozonation. .Kavanaugh points out that GAC processes

transfer pollutants from one environmental medium to another

creating further disposal requirements [31]. Oxidation

processes such as ozonation can convert toxic constituents to

innocuous by-products at costs comparable to GAC. Ozone

treatment is very efficient in oxidizing organics and killing

bacteria, only hydrogen peroxide in the presence of

ultraviolet radiation is a stronger alternative. Klien

reports that preozonation enhances flocculation, reducing

chemical coagulant requirements by as much as 1/3 and can

increase sand filtratiop rates up to 50% [lo]. Also, complete

oxidation of organics to CO, and H,O is possible but not

usually carried out due to prohibitive costs. Instead,

oxidation to carboxylic acids, ketones and aldehydes is most

cost effective. The oxidized organics can then be removed by

GAC which becomes biologically active as the products serve

as metabolites €or microorganisms, thus increasing the useful

lifetime of the carbon [lo]. In any case, ozonation requires

considerable investment as ozone must be generated on site by

passing 0, or air through a generator which produces a high

voltage electric field across the air stream. Power

consumption during generation is approximately 20-25 watts/g

ozone. Treatment tanks are needed ranging in size from 2 to

25

4 m3 with good mixing required. Ozone treatment at a level of

4 5 mg/l will decolorize dye wastes but some degradation

products may be produced as shown in Figure 1-7 [ 5 ] in which

Gould and SaunderS studied the effects of ozonation on dyes.

Also, as ozone is toxic and corrosive, it must be handled with

care and excess off-ozone must be destroyed. Lastly, heavy

metals and solids usually require separate treatment El], [ 2 ] ,

r31, [ S I , [ l o ] , 1311-

Ion Exchanse Resins. Ion exchange resins remove dyes

from wastewater at 93% removal efficiency, using a cation

cellulose exchanger followed by an anion exchange resin.

McRae [9] describes ion exchange as, Ita process in which small

ions in a first liquid solution are exchanged for other small

ions of likecharge sign from a solid or from a second liquid

insoluble in the first liquid solution.@I Two types of ion

exchange resins are shown in Figure 1-8 [ 9 ] . The fixed charge groups are the sulfonate (A) and quaternary ammonium (B)

groups which do not migrate according to McRae [9 3 . The M+

and X- counterions can migrate freely and carry -current

through the membrane. Mobile ions having the same charge as

the stationary charges do not easily permeate the membrane.

The exchangers can be regenerated by treatment with NaOH

solution. Macroreticulated resins can also be used, but

require a methanol rinse to clean the resin; the methanol can

be distilled off and recovered for reuse. A l s o , most dyes are

effectively removed except for disperse dyes. One advantage

..

26

. .

u 0 f-

0 40 . 80 120 hm 2c3C 240

Ozone a x e ( m q [-&) . .

Figure 1-7 Total organic carbon vs. ozone dose to study dye destruction of Acid B l u e 40 [ 5 ] .

27

F i g u r e 1-8 Schematic representation of ( A ) a cation exchange resin and (B) an a n i o n exchange resin [ 9 1 -

28

is that the final treated effluent can be reused for dyeing,

and that initial investment costs for an ion exchange system

are about 40% less than activated carbon with roughly 70% less

operating costs 123

Ultrafiltration - Water permeates through polymeric

membranes under pressure. The membranes usually have an

average pore size of 1 to 100 nanometers. Ultrafiltration can

be used for desalination, purification and or sterilization

according to Lanigan 163. The pore size is usually adequate

to remove large organic molecules, polymers and bacteria. The

waste stream is forced under pressure through the membrane

yielding purified water on the other side. Figure 1-9 shows

ranges of various separation processes as compared to

ultrafiltration [31]. Also shown are the primary factors

affecting separation [31] . Ultrafiltration reduces BOD, COD, and color. However, the membranes foul easily and must be

cleaned often, and they are not sufficient to remove heavy

metals 113, 123, 161, ~311.

Reverse Osmosis. Also called hyperfiltration - can remove smaller species than ultrafiltration. This process

works by the passage of impurities through a cellulose acetate

based non-porous membrane ackoss a pressure gradient. The

impurities are trapped on one side of the membrane where the

effluent begins to concentrate; on the other side emerges

purified water which can permeate through the membrane to be

reused or discharged. Organics with a molecular weight

29

PRIMARY FACTOR AFFECTING SEPARATION

I 1 1 MICROSCREENS

SIZE

I ULTRA FILTRATION 1 I I

I I

I 1 I GRANUALR MEDIA FILTRATION I I SURFACE CHARGE/ V O L T A G E

.4 .3 - 2 1 0 1 2 3 4

LOG SIZE @m)

F i g u r e 1-9 U s e f u l r a n g e s of s e p a r a t i o n processes [31].

30

greater than 100 g/mole are rejected by almost all reverse

osmosis membranes. For molecular weights of less than 100

g/mole, selectivity is based on molecular structure and the

membrane material. that is used according to Rautenbach and

Janisch [ 8 ] , Composite polymer membranes are currently being

developed. Most membranes have a lifetime of about 5-10

years, The process involves a very expensive capital

-

investment and membrane maintenance 113, [23, [ 4 ] , [ 8 ] ,

Electrochemical Wastewater Treatment

Electrochemical water treatment was developed approximately

20 years ago in response to the need for a method to remove

toxic metal ions from wastewater. Toxic metals are produced

as a waste material ,in such processes as electroplating,

battery production, photographic development, cellulose

acetate production and dye chemical production [7]. The

efficiency of an electrochemical reactor depends primarily on

the amount of specific electrode area and the mass transfer

possible. The larger both properties are, the more efficient

the reactor [7]. Also, because the concentration of metal

ions in wastewater is usually very small, the metal

electrodeposition reactions are mostly diffusion controlled

[7]. The equation governing diffusion controlled limiting

current density is as follows:

i = K v, Fc (1-1)

which gives rise to the main formula used in the design of

31

electrochemical treatment reactors:

-. p = O c M a e k c (1-2 1

which shows that f m treating low concentrations of metals in

wastewater, a high specific electrode area a, and large mass

transfer coefficient K are needed. The preceding parameters

are defined as follows:

i = current density (A/cm2) k = mass transfer coefficient (cm/sec) V,= F =

'p = a= M = a,=

c =

However, reactor

electron number (1) Faraday number (As/mole) concentrat ion (mole/cm3) space time yield (g/cm3*s) current efficiency (1) molar mass (g/mole) specific electrode area ( cm2/cm3)

performance cannot be effectively

measured unless it is studied along with wastewater properties

like inlet concentration and conversion on which it depends.

To meet this need a normalized space velocity eq?iation is

best suited to characterize the performance of the reactor and

which gives the volume of wastewater in 1.0 cm3 fo r which

impurities can be reduced by a factor of 10 during a'residence

time of 1.0 sec in a reactor volume of 1.0 cm3. The values ci

and c, represent inlet and exit concentrations while v is

equal to the'' voidage and I equal to the current (1).

32

There are three main types of electrochemical reactors

that are designed to produce a large mass transfer coefficient

and provide a high specific electrode area. Kreysa [7]

describes the reactor types as those which:

The mass transfer rate and the current density can be

enlarged by setting the electrodes in motion by using

turbulence promoters.

Have multiple cathodes or extended cathodes to create a

large surface area in a small cell volume.

Use a three dimensional electrode to achieve high mass

transfer coefficients and large specific electrode areas.

Because the use of electrochemical precipitators in the

textile.industry is a relatively new application, examples of

each type of reactor will be provided so that those with

minimum knowledge in this area may see what additional

processes are available and possibly applicable to textile

wastewater treatment.

TvDe A Cells

..

Type A reactor cells include the pump cell, the Chemelec

cell, and the ECO cell. Also included are cells with

vibrating electrodes or electrolytes.

The pump cell [19] is shpwn in Figure 1-10. It consists

of two stator disc electrodes, also acting as endplates with

electrical connections. A bipolar rotating disc electrode is

mounted on a rotating shaft which runs between the endplates.

The electrolyte or wastewater flows through the central tube

FLOW

FLOW

MAGNETICALLY DRIVEN ROTOR RUNNING ON CERAMIC SHAFT

Figure 1-10 Schematic diagram of a b i p o l a r pump ce l l [ 1 9 ) . 1

W W

34

to the outer circumference of the rotating electrode. The

rotation of the electrode creates a high mass transfer

coefficient which can be increased or decreased by changing

the rotation speed. The residence time is determined by the

radial flow rate.

The Chemelec cell [203 is shown in Figure 1-11. It uses

a fluidized bed of glass spheres (fluidized by electrolyte

flow) to promote turbulence around the numerous electrodes

increasing mass transfer. Several stationary monopolar plate

electrodes are employed along with glass spheres averaging 1.0

mm in diameter. According to Kreysa, the mass transfer can

be increased up to a factor of six compared to the same

processes using laminar flow [7]. Chemelec cells are

currently used by the electroplating industry to remove metal

ions from rinsing waters, thus maintaining a constant metal

concentration in the primary rinsing bath which is continually

..

reused.

Another cell which uses a rotating electrode is the ECO

cell shown in Figure 1-12 [21]. Many reactors can only attain

a limited degree of conversion in a single pass, butthe ECO

cell uses consecutive baffles which create mini reaction

chambers through the course of the cell. One rotating

cylinder of about 50 cm diameter acts as the cathode to all

chambers. The wastewater successively flows through each

chamber almost eliminating back mixing effects while achieving

high degrees of conversion.

35

MESH ELECJ

-INLETS I

Figure 1-11 Schematic diagram of t h e Chemelec cell [20].

36

- catholyte c a t h o l y t e :a..i-i-r r r T T

-

/ b a f f l e pl a t e s

-. --.

ro t a t ing cy1 inder cathode O Q

-.

F i g u r e 1-12 Schematic diagram of the ECO cell [21].

.-.. $0 A 1_11_1_1_LI_L-

I -

37

TvDe B Cells

Type B cells are designed to accommodate a large

electrode area in a small cell volume. The electrodes are

generally stationary, but their large surface area makes up

for lack of motion. The multicathode cell, Swiss roll cell

and the ESE cell are examples of type B cells.

Multicathode cells like the one pictured in Figure 1-13

[22] are used in gold recovery. However, multicathode

stacking is limited by the fact that ohmic losses occur inside

the stack, thus reducing the penetration depth of the current.

The thickness of the electrode stack is limited to 5-10

electrodes, any additional electrodes will have very little

electrochemical activity and thus merely serve to increase

space requirements.

Another type B cell employs an innovative design which

uses an electrode wrapped helically around a core, this cell

is appropriately named the Swiss-roll cell pictured in Figure

1-14 Metal foil sheets separated by a plastic mesh are

wrapped helically around a core. The wastewater flows along

the electrode roll axis; the metals being removed by

deposition on the cathode foil. An acid wash is used to

remove metals and regenerate the foil. Large space time

yields can be obtained due to the large specific electrode

area.

[23].

Like the Swiss-roll cell, the ESE (Extended Surface

Electrolysis) cell also uses a rolled electrode, only using

38

0- D S A mesh anode

ion exchange membrane /

I I I I I I I 1 I I 1

t

anoly te was te w a t e r

mult i-mesh cathode

Figure 1-13 Schematic diagram of the multicathode cell [ 2 2 1 -

39

F i g u r e 1 - 1 4 Schematic diagram of t h e Swiss-roll cell [ 2 3 ] .

40

mesh electrodes instead of foil. With a mesh electrode three

dimensional exposure and radial flow can be achieved.

Industrially this type of cell is used successfully to remove

copper from electcoplating wastewater [ 7 ] .

Type C Cells

Type C cells use a three dimensional electrode structure

to increase the cell capacity, the mass transfer and increase

the specific electrode areas.

One unique design shown in Figure 1-15 [ 2 4 ] depicts a

porous flow through cell which uses cylindrical packed beds

of conductive particulate matter for both the anode and the

cathode. The wastewater enters the cell between the

electrodes, and actually enters the two electrodes through

porous plastic. Operational valves are used to adjust flow

rates such that 99% of the effluent moves through the cathode

while only 1% moves through the anode. Once the cathode is

filled with waste metal, the whole unit is turned upside down

so that the loaded cathode becomes the anode. The trapped

waste metal is dissolved anodically, and the wastestream

produced is a concentrated metal salt solution. The cell can,

therefore, be continually operated. -. Another type C cell known as the RETEC cell [25] is shown

enlarged in Figure 1-16. The RETEC cell cathodes are metal

sponge electrodes with an active surface area 15 times greater

than their geometric area. It is used in closed loop rinse

water systems by the electroplating industry to maintain metal

41

inlet

1 ,( diluted product h

concentrated

€

product

Figure 1-15 Schematic diagram of the porous flow-through cell [ 2 4 ] .

42

' AIR SPARGER THE RETEC-50 CELL

F i g u r e 1-16 Schematic diagram of the RETEC cell [ 2 5 ] .

4 3

particle inlct

P Onode

cathode fecdcr electrode

CQ t holy ie oui lei

I I cat holyt c o noly te

anolyte outlet

membra t-4 e

Figure 1-17 Schematic diagram of the fluidized bed cell [ 2 6 1 -

4 4

' concentrations at a reasonably low level.

Lastly, an example of a three dimensional exposure,

fluidized bed cell is shown in Figure 1-17 [26]. This cell

was designed by Goodridge and Fleischmann. The wastewater

flows from bottom to top fluidizing the loose bed of particles

as it passes through. The particles are charged cathodically

by a feeder electrode and metal ions are deposited

cathodically on the particles. The particles grow large and

heavy as they collect metal ions, thus causing them to migrate

to the lower part of the bed where they are removed. Fresh

particles are fed into the top of the bed. So, as the inlet

water flows upward, its metal content decreases. For

hydraulic reasons, the height of the cell is usually

restricted to about 2 m. To increase residence time, the

wastewater can be recycled through the unit or several beds

may be connected in a series.

Although electrochemical wastewater treatment is

primarily used for metals removal, interest has recently been

directed toward the study of its applications in textile

wastewater treatment. Andco Environmental Processes, Inc. of

Amherst, New York has recently begun research to determine the

effectiveness of their electrochemical treatment process and

its applications in textile wastewater treatment.

45

The Andco Treatment Process

Andco’s electrochemical treatment unit is most closely

A diagram related to the type B reactors described earlier.

of the Andco reactor is shown in Figure 1-18 1141. It

contains multiple electrodes, the exact number depending on

the reactor size. Andco produces several different size

treatment units depending on an individual’s treatment needs

determined the volume of wastewater produced. The Andco

Process uses sacrificial iron electrodes to produce ferrous

ions which are continually entering the wastewater as it

passes through the reactor. The ferrous ions co-precipitate

heavy metals as metal hydroxides. If present, dyes and

pigments are also adsorbed onto the iron matrix. A small

amount of high molecular weight, high charge density anionic

polymer is added to assist in floc formation by helping to

form large particles which settle out easier. A bottom sludge

of 1-2% solids forms: this sludge requires additional disposal

cost. Sludge production and investment costs will be

discussed later.

As a type B reactor, the influent enters at the bottom

of the Andco cell and is pumped upward between the egectrodes.

As the current flows from electrode to electrode, they begin

to dissolve into ferrous ions as given in the electrochemical

reactions below:

Anode: Fe ---- > Fe” + 2e-

46

Figure 1-18 Schematic diagram of the Andco Electrochemical Treatment cell [14].

47

Cathode: 2H,O + 2e- = H, + 20H- The sum of the reactions are as follows:

Fe + 2H,O + Electrical Energy = Fe(OH), + H, ..

The Fe(OH), forms HM'Fe(OH), where HM = Heavy Metals, and

pollutant'Fe(OH),. It is observed that like the process

occurring in electroplating baths, the anode dissolves as the

current is applied; however, instead of the metals plating out

of solution at the cathode, hydrogen gas production occurs at

the cathode. The hydrogen produced is not directly involved

in the flocculation process, but may interfere with the

flocculation process if it is not allowed to escape. For this

reason a hydrogen gas vent is built into the Andco reactor

design.

Heavy metals and organics adsorb well onto the ferrous

hydroxide matrix, because it has such an active surface.

Also, the process can be carried out at one pH. The ,Andco

Process is operated with the influent wastewater adjusted to

pH 7-9. The upper limit pH is actually determined by local

regulations on pH discharge limits. Figure 1-19 [14] shows

the solubility limits of some common metal ions. The given

values are for metals in pure water so their solubilities may

vary significantly in a mixed wastewater stream. Because each

individual metal has a minimum solubility at a different pH,

pH adjustment to force one metal to precipitate may adversely

effect the precipitation of another metal [14]. Ferrous

4 8

10

1.c

2- 0 e7

0.0 I

.I 0.031

4 i

/ €e+! It -\

/ v

- I O

1 \

I

- I

Figure 1-19 Solubility limits of some common metal ions [14I

49

hydroxide, fortunately, increases the span of pH's at which

metals will precipitate. It also disrupts the equilibrium

between dissolved and precipitated metals. As the ferrous

hydroxide removes. the metals, the dissolved metals remaining

are pushed to become insoluble to meet equilibrium

requirements.

The simplicity of this process and its ability to treat

highly variable waste streams make it a formidable candidate

among the forementioned variety of treatment systems

available.

Initial testing performed by Andco Co. at several pilot

operations using the Andco Electrochemical Treatment Process

has shown that several types of textile pollutants are reduced

to various degrees depending on the operational values used.

The following data are the results which Andco Co. has

obtained to date. These values will later be compared with

test values observed in this study.

Andco Environmental Processes, Inc. has reported that

their process efficiently reduces color, BOD, COD and heavy

metals in textile wastewater. Demmin and Uhrich of Andco have

reported efficiencies of 50-70% for BOD and COD reduction,

greater than 90% for color reduction, and 80-100% for heavy

metals reduction [ 3 ] .

Specific results have shown that BOD levels were reduced

by 30-55% as shown in Table 1-5 [ 3 ] . Additionally, COD values

were reduced 50-70% as shown in Table 1-6 [ 3 ] . As observed,

50

Table 1-5 Electrochemical treatment BOD reduction [ 3 ] .

Source Description Influent Electrochemical Effluent % Reduction BOD5(mdL) Iron(mg/L) BODS(mg/L)

Nylon dye mixture 96 100 containing GJ

sulfur, Md reactive

Cotton dye mixture 108 150 of vat, disperse,

Nylon carpet Mill # I 377 acid dyes Nylon carpet Mill d 2 41 I acid dyes Nylon carpet Mill 1 3 455 acid dyes

100

100

300

38

. 78

60

28

09 19 1

190 54

2 0 0 5 2

e .

51

Table 1-6 Electrochemical treatment COD reduction 133.

Source Description

Nylon carpet Mill # 1 acid dyes Nylon carpet Mil l 112 acid dyes Nylon carpet Mill 6 3 acid dyes Nylon carpet Mill Lc4 acid dyes

Nylon carpet Mil l 115 acid dyes Nylon dye mixture containing Cu Cotton dye mixture of vat, disperse, sulfur, and reactive dyes

Influent COD(mg/L)

1012

1017

11s1

1776 .

560

9 50

E lec t rochem ica I Iron(mg/L)

100

100

IO0 300

IO0

IO0

IO0

Effluent COD(mg/L)

436

556

526 466

685

174

332

% Reduction

57

4s

54 60 . 61

69

65

57s 150 205 .64

52

these values can be compared to data from Tincher [17] in

Table 1-7. The values in Table 1-7 were acquired from the

Dalton Riverbend Wastewater Treatment Plant, and they show the

percent reduction. in COD after treatment with the Andco

Process. Reduction values average 45-60%. Reduction levels

depend on the type of chemical being removed, its

concentration and the iron (mg/l) level added. It must be

pointed out that part of the tests were performed on actual

textile mill effluents, while the remainder were performed on

laboratory simulated mixtures and isolated stock chemicals.

A Color Graph double beam spectrophotometer was used to

test for color reduction. Color removal was demonstrated in

Figures 1-20 and 1-21 [ 3 ] . These two figures represent two

different reactive dye mixtures treated from different cotton

textile manufacturer's effluents. It was observed that the

% transmittance increased as the iron treatment level

increased. An increase in % transmittance corresponds to a

decrease in color intensity. Care should be taken to observe

the % transmittance at any given iron treatment level in the

region where the dye normally has its highest absorbance (or

lowest transmittance). In this way color removal is not

confused with the normal increases in % transmittance that

occur at various points in a spectrum characteristic for each

dye or colored constituent. Table 1-8 [ 3 ] provides an

absorbance reduction % for a variety of dyes and dye mixtures.

Absorbance readings were taken at the approximate maximum

53

Table 1-7

D y e h o u s e E f f l u e n t WTP I n f l u e n t WTP F f f l u e n t

COD reduction after electrochemical treatment ~ 1 7 1 .

C h e m i c a l Oxygen '6ZEiand

Before T r e a t . A f t e r T r e a t .

1017 1 1 5 1 575

5 5 6 5 2 6 223

X Red.

4 5 54 61

54

H I

MI

V

Figure 1-20 Electrochemical treatment color removal from red reactive dye mixture [ 3 ] .

55

..

l a

Ui.1

m.0

W.0 ,

a.0

I - /

F i g u r e 1 - 2 1 Electrochemical t r e a t m e n t co lo r r e m o v a l f r o a reactive dye m i x t u r e [ 3 ] .

56

Table 1-8

Source Description

1.

2.

3.

4.

5.

6.

Nylon dye mixture containing heavy metals

Cotton dye mixture of vat, diJperse, sulfur, and reacrive dyes

Beverage product natural coloring agenrs

Brilliant blue, fiber reactive dye (1: 1000 dilution)

Brilliant red. fiber reactive dye (1:lOOO dilution)

Acid red 106

7. Basic red 2

Electrochemical treatment color removal [ 3 ] .

Influent Color: Absorbance ( n d , pr-co Units o r mg/L

0.227 (400 nm)

0.373 (400 nm) 0.318 (465 nm) 0.418 (525 nm) 0.535 (600 nm)

7412 P t C o Units (465 nm) 7412 ”

180 ”

0.695 (400 nm)

6.00 (525 nm)

5.48 (532 nm)

100 mgIL

Electrochemical Resulting K Reduction Iron (mg/L) Effluent Color in Calor

(same units)

mo

I so

104 212 200

500

208

100 200

50 SO0

0.020

0.033 0.019 0.0 It 0.023

6769 770 SO

0.026

0.0 I I

1.72 0.069

62 m g h 10 mg/l

91

91 94 96 96

‘ 9

56

96

9o

99+

69 98

38 90

57

absorbance wavelength (nm) for each respective sample. The

iron treatment levels were varied resulting in different

degrees of color reduction. In general, the highe-r the iron

level added, the.higher the color removal. Also, color was

measured in Pt-Co Units or mg/l. These values can be compared

to Tincher's 1171 values for color reduction from dyehouse

effluent, WTP influent and WTP effluent in Table 1-9. It is

observed that at a certain maximum of iron treatment the color

removal does begin to "bottom off" and further treatment

produces no further pollutant or color reduction. Iron levels

of 200-500 mg/l remove color by approximately 90-98%.

However, at high iron addition levels, large amounts of iron

sludge are produced.

The original testing of textile wastewater performed by

Andco was done to test the efficiency of heavy metal removal

from rinse water containing premetalized dyes from the

manufacture of automotive upholstery. It was during this

testing that Andco discovered its process had possible

applications in the treatment of other textile wastewater

components like BOD, COD and color. Table 1-10 [ 3 ] shows the

increasing degree of heavy metal removal of Cr, Cu and Co with

increasing levels of electrochemically generated iron. At 4 0 6

mg/l of iron, reduction values were 98%-99.9%. At very low

concentrations of the metals, analytical error increases due

to the detection limits for the metals.

58

...

Table 1-9 Absorbance values before and after electrochemical treatment with percent reduction of absorbance 1171.

Absorbance Before Treatment

6 1 0 - 5 10 - 4 1 0 - 250 220

Dyehouse E f f l u e n t WTP I n f l u e n t WTP E f f l u e n t

Dyehouse E f f l u e n t WTP I n f l u e n t WTP E f f l u e n t

Dyehouse E f f l u e n t WTP I n f l c e n t WTP E f f l u e n t

0.050 0 . 0 7 2 0 . 1 3 3 0 . 8 8 1 2 .23 0 .056 0 . 0 8 1 0 . 1 4 4 1 . 3 1 2 .80

2.85 0 . 0 5 3 0 . 0 7 9 0 . 1 4 4 1 . 2 5

Absorbance A f t e r Treatment

- 610 - 5 1 0 ' 410 - 2 5 0 - 220

0 . 0 0 0 0.000 0 . 0 1 8 0 . 3 3 1 0 . 8 6 0.031 0 . 0 5 4 0.102 0 . 8 3 0 1.71 0.006 0.016 0 . 0 3 6 0 . 5 6 2 1 . 1 9

Per Cent Reduct ion i n Adsorbance

610 - 5 1 0 - 4 1 0 2 5 0 220 ..

100 1 0 0 86 6 2 61

8 9 8 0 7 5 55 5 8 4 5 3 3 2 9 3 4 39

59

Table 1-10 Heavy metal removal w i t h increasing l e v e l s of electrochemically generated iron 131.

Table VI: Heavy metal removal with increasing levels of electrochemically generated iron

I !

Electrochemical Iron (mg/L)

0 142 174 206 273 318 406

Cr g l s m

1920 370 260 260 210 150 50

cu o l d )

820.0 2.0 3.6 3.6 4.0 2.2 1.8

co @€!A)

1090 20 10 10 4 3 2

60

Demmin and Uhrich report that the mechanism for removal

of contaminants from wastewater by electrochemical treatment

is not fully understood. It is thought that various organic

and inorganic species adsorb onto the ferrous hydroxide matrix

as it forms in the electrochemical cell. Assuming that

equilibrium is attained during treatment, Demmin and Uhrich

report that "data from adsorption phenomena often follow the

Freundlich isotherm equation1# [ 3 ] . Mathematically the

Freundlich isotherm equation is given by

q, = KFCe""

where q, is the weight of contaminant adsorbed/weight of

adsorbent (the reduction of contaminant per mg/l iron added.

Also, Ce is the final equilibrium of contaminant (the final

contaminant level), KF and n are constants.

In Ce yields a straight line relation [3].

Plotting In q, vs.

Demmin and Uhrich explain that although not all

contaminants are necessarily removed by adsorption, data

support that heavy metals are removed in this manner. They

also emphasize that to konclusively prove that adsorption is

occurring, extensive and controlled laboratory tests will need

to be performed [ 3 ] .

CHAPTER I1

RESEARCH.OBJECTIVE AND EXPERIMENTAL DETAILS

The goal of this research was to evaluate the

effectiveness of the Andco Electrochemical Treatment Process

and its applications in textile wastewater treatment. A pilot

unit was set-up in the Textile Engineering Department and test

samples were developed by using laboratory simulated textile

wastewater. The research was divided into four principal

sections. First, a study to determine how effectively the

Andco Process reduces chemical oxygen demand (COD)

concentrations for certain types of textile wastewater.

Second, a study using an absorption spectrophotometer to

determine the extent of color removal of various acid dyes.

Third, a study to determine if exhausted dyebath water can be

reused after treatment by the Andco Process. And fourth, a

study to determine whether dyes are removed by adsorption

alone, or if they are chemically altered in sdme manner by the

treatment system.

Experimental Methods and Procedures

Andco Pilot Unit (M-Cell) Operation Procedure

The M-Cell is a small portable test unit used to simulate

the operation of full scale systems. The M-Cell contains an

electrochemical cell consisting of two 1/8 inch cold rolled

62

steel plates separated by an 1/8 inch gap. The steel plates

act as electrodes which carry a current provided by a D.C.

power supply, which is connected across the end electrodes.

The current passes from electrode to electrode through the

wastewater stream that flows through the 1/8 inch gap. As the

current flows, the electrodes dissolve putting ferrous ions

into the wastewater [14]. For the duration of this study, the

wastewater was continually recycled through the unit instead

of making a single pass. This allowed greater freedom to

study efficiencies at different iron levels. The circulation

time required to achieve a given iron level was calculated

using the following equation [14]:

Time = Volume (sal) rDesired Iron Level ms/ll .2175 (min) Current (AMPS) (2-1)

Any value calculated having a decimal value such as 3.50 can

be changed to minutes and seconds by multiplying the number

following the decimal by 60 sec (ie 3.50 = 3 min 30 sec)

This value is the recirculation time required to put the ..

desired amount of iron into the sample. Care must be taken

to account for the volume loss after each sampling. One must

also remember that the iron accumulating in the sample is

additive. Sample calculations for iron levels from 50 to 650

mg/l are shown in Figure 2-1. The volumes are given in

gallons. The quantity of each sample taken is approximately

500 ml and the amperage is kept constant at 13 Amps (although

6 3

FORA C0N"OUS SERIES OF IRON IEVELS FROM 50 MG/L TO 650 MG/L IRON LZVEL

1) [( 3.16 gal )( 50 mg/Liron )( 0.2175 11 / 13 amps = 2.64 --> 2min.. 39 sec

2) [( 3.03 @)(lo0 *Limn)( 02175 )I / 13 amps = 5.07 ---> 5min.. 4 sec

3)[( 2.89gal )(lo0 mg/Liron )( 0.2175 11 / 13 amps = 4.84 -> 4min.. 51 sec

4)[( 2.79@)(100 mg/Liron)( 0.2175 )I / 13 amps = 4.62 ---> 41Ilin.. 32 sec

5)[( 2.63@)(100 mg/Liron )( 0.2175 I1 / 13 amps = 4.40 -> 4min.. 24 sec

6)[(2.5Ogal)(100mg/Liron)(0.2175)] / 13 amps =4.18 ---> 4min.. 11 sec

7)[( 237gal )(lo0 mg/Liron)( 02175 )I / 13 amps = 3.96 -> 3min.. 58 sec

nrrALTLME . 29MIN..39SEC

FORA SIN= SAMPIE WITH A RJ3QUlRED IRON UXEL OF 6!5OMG/L :

8)[(3.16gal)(650mg/Liron)(O.2175)1/ 13amps =34.37 --> 34mh.22sec

Figure 2-1 Sample calculations for electrochemical iron addition.

64

the amperage value can be changed if desired). Lowering the

value of the amperage increases the waiting time required for

each sample to reach a given iron level. The ttM1l-cell should

not be operated at a current higher than 15 Amps. The water

flows through the reactor cell from bottom to top at a rate

controlled by a flow control valve. Exiting water appears as

a muddy dark-green liquid due to the ferrous ion; however,

after exposure to air during the recirculation process, a

portion of the ferrous ion oxidizes to the ferric state giving

the water a dark black and finally a rust colored appearance.

After flocculation and clarification, the water will be clear

and the metal hydroxides will be collected as a sludge.

The amperage of the ttMtl-cell can be adjusted using the

voltage knob which is calibrated in percent of maximum output

voltage. The maximum output is 4 5 volts. An ammeter and

voltmeter are provided on the control panel so that the

current and voltage across the cell can be monitored. The

voltage at a given amperage depends on the conductivity of the

wastestream. The higher the conductivity, the lower the

voltage requirement needed to attain a given amperage. A

small amount of salt (approximately 1-3 grams) may be added

to low conductivity waste streams to reduce voltage

requirements or to attain a higher amperage. Lastly, the I 1 M 1 l

cell requires a 120 volt, 1 phase, sump power connection.

Before any samples are passed through the machine, it

Large scale units require one ten minute must be acid washed.

65

acid wash everyday; however, due to the nature of the

analytical tests being performed, the pilot unit was acid

washed between each major chemical change (ie between two

different dyes or chemicals) and tapwater rinsed between each

concentration change within 'a series of tests on any one

chemical. The acid wash consists of 15-17% hydrochloric acid

solution totaling 6.0 1 which is pumped through the machine

for 10 minutes at 13 amps. The acid wash is followed by a

tapwater rinse lasting about 2-3 minutes.

Sample Preparation for the llM1l-Cell Unit

Through the entire course of this research, the sample

volume used in each experiment was 12 liters or 3.16 gallons

unless otherwise indicated. The sample bucket which is

attached at the base of the llM1t-cell was calibrated and marked

at 12 liters for testing convenience. Each sample treated by

the unit was calculated for concentration in mg/l. Sample

chemicals were mixed directly into the 12 liters of distilled

water in the sample bucket (distilled water was used for all

samples tested except when otherwise indicated). In each

case, a small aliquot (approximately 50 ml) of stock solution

was taken as a control sample future testing and comparison

with treated samples.

The operation manual [14] suggests pH adjustment of the

sample prior to treatment in the range of pH 7-9 [14].

Caustic NaOH solution and H2S0, solution were used for pH

adjustment; for consistency of test procedures each sample was

66

adjusted to pH 8.3-8.5 before treatment. Also, in almost all

cases some salt ( ' about 1 to 3 g NaC1) was required to

increase the conductivity, and thus, achieve the desired

amperage. The flow was started and water circulated before

the voltage is applied- This allows for flow adjustment (1.5

- 2 gallons/minute was used as the procedure flow rate). A

stopwatch was used to monitor the recycle time. The start up

time actually began when the amperage was turned on and the

electrodes began to dissolve. All times were monitored

starting at this point. When the first iron level was

reached, the amperage was cut off and the water allowed to

circulate for 1 minute to create a uniform iron level in the

sample bucket. A 500 ml sample was collected in an Erlenmyer

flask directly from the exit tube. The amperage was turned

on and recycling continued until the next iron level was

attained, at which time the next sample was collect as above

and so on until samples of all desired iron levels had been

acquired-

Each flask was labeled with its sample type and iron

level. After the sample was taken from the machine, its

llexitvv pH was recorded using a digital pH meter. Also,

hydrogen bubbles created during the treatment process were

allowed to degas, occasional mixing accelerated the degassing

process.

Once no bubbles were visually present, the sample was pH

adjusted to approximately pH 8.8-9.2 before polymer addition.

67

During the course of experimentation it was found that

different chemical samples flocced best at a characteristic

pH which was determined through trial and error. The polymer

used for all samples was an anionic polyacrylamide copolymer

type 3640 manufactured by Aries Chemical, Inc. A 0.2%

solution of the polymer was used to flocculate the samples.

Roughly 0 . 2 5 to 2 . 5 ml of polymer was required to flocculate

a 500 ml sample. The amount of polymer added was not closely

monitored until it became suspect in contributing

significantly to COD and TOC measurements, after which exact

polymer additions (ml) were recorded. After polymer addition,

floc formation was usually observed followed by a settling out

process. The clear surface water was decanted into a beaker

and then filtered through glass wool to remove iron

particulates. Filtered samples were stored in glass bottles

and refrigerated until applicable tests could be performed.

Also, the machine was rinsed out with tapwater after sample

collection was complete. A- picture of the Andco 18Mt8-cell unit

is shown in Figure 2-2 [14]. -.

Analytical Testins Procedures, Methods and Equirsment

Chemical Oxysen Demand Studv -.

One of the main tests performed on almost all of the

samples was a COD or chemical oxygen demand test. This test

measures the amount of oxygen needed to oxidize any organics

or oxidizable inorganics to CO, and H,O. This is not to be

69

confused with the BOD or biological oxygen demand which

measures the amount of oxygen required by microorganisms to

break down biodegradable compounds in a standard time of

usually 5 days. The COD is a more comprehensive value taking

into account both biodegradable and nonbiodegradable

..

oxidizable constituents. CODtests were performed on both the

sample stock solution before treatment and the samples taken

after treatment as described earlier. COD tests were run on

stainblocker chemicals, dyes, auxiliary chemicals, distilled

water and blank samples.

The COD test is a titration experiment. Titrants of

varying degrees of strength were prepared in an attempt to be

"in range" for the variety of chemicals used and their

respective COD ranges. The COD test -method was taken directly

from the EPA manual Methods For Chemical Analvsis of Water and

Wastes [15]. For samples having high COD'S the titrants used

in the method were strengthened to increase the COD test

range. Likewise, for low COD samples, the titrants were

diluted to increase the accuracy of the volume determination.

Stainblocker chemical samples and auxiliary chemicals required

medium to high strength titrants while dyes and distilled

water required low strength titrants.

COD Method and Procedure. Organic constituents in the

sample are 'oxidized by potassium dichromate in a 50% (by

volume) silver sulfuric acid solution. Silver sulfate serves

as a catalyst and mercuric sulfate is added to remove any

70

chloride interference. The excess potassium dichromate is

titrated with standardized ferrous ammonium sulfate using

orthophenanthroline ferrous complex (ferroin) as an indicator .. 1151 .

High level COD tests were used for older stainblocker

chemicals and auxiliary chemicals. The high level test has

a maximum range of 1000 mg/l COD. The high level titrants

were prepared as follows:

1 ) Potassium dichromate titrant 0.25 N was prepared by

baking 12.84 g of K2Cr,07 at 14OoC for two hours to remove

moisture and then dissolving in a 1000 ml volumetric

flask with distilled water and mixing.

2 ) Ferrous ammonium sulfate tirant 0.10N was prepared by

adding 39.00 g of ferrous ammonium sulfate to a small

amount of distilled water in a 1000 ml volumetric flask

9

with swirling and addition of 20 .0 ' ml of concentrated

sulfuric acid. The titrant was then diluted to the mark.

COD SamDle PreDaration

1) In a clean 500 ml ground glass Erlenmyer flask was placed

U.4g Of Hg2S04 (mereuriz: Sulfate) fclllowed by 20.0 ml Of

sample water and 10.0 ml of K2Cr207 0.25 N titr'ants.

The flask was placed in'.an ice bath to reduce fuming as 2 )

3 0 . 0 ml of H2S04.AgS04 solution was added.

boileezers were added and the solution was mixed.

Several

3 ) The flask was connected to a condenser over a hot plate

as shown in Figure 2 - 3 . The solution was slowly brought

71

Outlet

. . , ,I1(.Reflux Cond I .

ensor

+Water I n J e t

\ 500 ml Erlenmyer Flask

,g Hot Plate

Figure 2-3 Schematic of COD test appara tus .

72

to a boil and allowed to reflux for 2 hours before being

allowed to cool to room temperature.

4 ) Once the oxidized solution was removed from the COD ..

apparatus, the volume was brought up to 150 ml with

distilled water.

5) Six drops of ferroin indicator was added and the sample

was titrated with ferrous ammonium sulfate 0.10 N

titrant.

blue-green to a reddish hue was recorded.

The ml needed to achieve the color change from

With each set of COD tests performed, a blank of

distilled water was tested. The blank was prepared in

the exact manner as a normal sample except that the 10.0

ml of sample volume was substituted with 10.0 ml of

distilled water. The blank was titrated and the volume

included in the final COD calculation to subtract off

background contamination. The equation used to calculate COD

concentration is given below [15]:

COD, mg/l = 1A-B) N x 8000 c2 -21 S

C .

Where

A = Milliliters of Fe(NH,),(SO,), required for titration of the blank.

B = Milliliters of Fe(NH,),(SO,), required for titration of the sample.

N = The Normality of the Fe(NH,)2(S0,)2 titrant.

S = Sample volume used in the test (ie 10.0 ml)

8,000 is a constant value

7 3

The medium level COD test used for reduced COD

stainblocker chemicals has a maximum range of 500 mg/l COD.

All sample preparation for this test is identical to the high

level test except that the titrants used are 0.05 N ..

Fe(NH,)2(S0,)2 and 0.125 N K2Cr207.

The low level COD test used for dyes and distilled water

blanks (run through the rrMrt cell with polymer addition) has

a maximum range of 250 mg/l COD. Note must be made that the

distilled water blanks run through the IrMrr cell are test

samples which are not to be confused with COD distilled water

reference blanks. As above, all sample preparation remains

the same except that the titrant strengths used are 0.025 N

Fe(NH,)2(S0,)2 and 0 . 0 6 2 5 N K2Cr20,.

The titrants were kept refrigerated and were used for no

more than two weeks before discarding and preparing fresh

titrants. A standardization of the titrants was carried out

before the titrants were used in any COD tests. ACS grade

0.025 N K,Cr,O, standard solution was used to standardize the

Lab prepared ferrous ammonium sulfate. A back titration wag

then carried out to determine the normality of the lab

prepared K,Cr,07. The normality was calculated 'using the

following relation [15]:

where N = Normality. ( 2 - 2 )

7 4

tests were run on the following samples:

Stainblocker A - 0.1 g/l, 0.3 g/l, and 0.6 g/l, solutions. The high level test was used.

Stainblocker A - 0.6 g/1 stock solution and 0.6 g/1 solutions treated at 200, 400, 500 and 650 mg/l iron addition. The high level test was used.

Stainblocker A - 1.0 g/1 stock solution and 1.0 g/1 solutions treated at 500 and 650 mg/l iron addition. The high level test was used.

Stainblocker D - 1.0 g/1 stock solution and 1.0 g/1 solutions treated at 150, 250, 350, 450, 550 and 650 mg/l iron addition. The high level test was used.

Stainblocker D - 0.6 g/1 stock solution and 0.6 g/1 solutions treated at 550 and 650 mg/l iron addition for each. The high level test was used.

Stainblocker D - 0.6 g/1 solutions treated at 550 and 650 mg/l iron addition, however, with only settling (no polymer addition to achieve floc). The high level test was used.

Stainblocker B - 0.6 g/1 stock solution and 0.6 g/1 solutions treated at 450, 550, and 650 mg/l iron addition. The medium level test was used.

Stainblocker B - 1.0 g/1 stock solution and 1.0 g/1 solutions treated at 450, 550 and 650 mg/l iron addition. The medium level test was used.

Stainblocker B - 0.6 g/1 stock solution and 0.6 g/1 solutions treated at 450, 550 and 650 mg/l iron addition. the medium level test was used.

Stainblocker C - 1.0 g/1 stock solution and 1.0 g/1 solutions treated at 450, 550 and 650 mg/l iron

Stainblocker C - 0.6 g/1 stock solution and 0.6 g/1 solutions treated at 450, 550 and 650 mg/l iron addition. The medium level test was used.

Irgalev A - 0.3 g/1 stock solution. was used.

Irgalev A - 0.6 g/1 stock solution and 0.6 g/1 solutions treated at 250, 350, 450, 550 and 650 mg/l iron addition. The high level test was used.

addition. The medium level test was used.

The high level test

75

Irgalev A - 0.9 g/1 stock solution and 0.9 g/1 solutions treated at 250, 350, 450, 550 and 650 mg/l iron addition. The high level test was used.

Irgalev A - 0 . 8 g/1 stock solution and 0.8 g/1 solutions treated at 25.0, 350, 450, 550 and 650 mg/l iron addition. The high level test was,used.

Guar Gum - 0.6 g/1 stock solution and 0.6 g/1 solutions treated at 250, 350, 450, 550 and 650 mg/l iron addition. (This test was performed twice). The high level test was used.

Guar Gum - 0.3 g/1 stock solution and 0.3 g/1 solutions treated at 250, 350, 450, 550 and 650 mg/l iron addition. The high level test was used.

Distilled Water - Distilled water treated at 50, 150, 250, 350, 450, 550 and 650 mg/l iron addition with carefully measured polymer addition (to assess residual polymer COD contribution to treated samples). The low level test was used.

Acid Dye Mixture - Acid Blue 277, Acid Red 361, Acid Orange 156, 25 mg/l stock solution and 25 mg/l solutions treated at 50, 150, 250, and 350 mg/l iron addition. The low level test was used.

Acid Dye Mixture - Acid Blue 277, Acid Red 361, Acid Orange 156, 50 mg/l stock solution and 50 mg/l solutions treated at 50, 150, 250 and 350 mg/l iron addition. The low level test was used,

Acid Red 361 25 mg/l stock solution and 25 mg/l solutions treated at 50, 100, 150, 250, 350 and 450 mg/l iron addition. The low level test was used.

Acid Red 361 50 mg/l stock solution and 50 mg/l solutions treated at 50, 100, i50, 250, 350 and 450 mg/i iron addition, The low level test was used.

Procion Blue MX-2G 25 mg/l stock solution and 25 mg/l solutions treated at 50,;100, 150, 250, 350 and 450 mg/l iron addition. The low level test was used.

Procion Blue MX-2G 50 mg/l stock solution and 50 mg/l solutions treated at 50, 100, 150, 250, 350 and 450 mg/l iron addition. The low test was used.

76

All samples were prepared from 1.0 g/1 stock solutions of the

desired chemicals. Concentrations were calculated as the

number of ml of 1.0 g/1 stock in the 12 liter volume required

for each lot to be run through the Andco "M" cell. Before

treatment, a small sample of the mixture was recovered and

stored to serve as the standard. So, for a 25 mg/l dye l o t ,

300 ml of 1.0 g/1 dye solution is diluted in the Andco bucket

to 12 1. The sample taken before treatment is approximately

25 mg/l and serves as the standard stock solution.

In addition to the COD test, the total carbon (TC) test

was run on several selected samples of stainblockers, dyes,

and blanks. The TC apparatus uses very high temperatures,

( 1600°F in this set of tests) to oxidize carbon containing

organics and inorganics to carbon dioxide which passes through

an infrared light detector similar to an IR spectrophotometer

except instead of scanning a field of wavelengths there is

only one wavelength studied. That wavelength corresponds to

the carbon dioxide stretch and so senses and quantifies the

amount of carbon present as CO,. The amount present is

proportional to the peak height and must be compared to peak

heights produced using potassium hydrogen phthalate -standard.

Peaks of the same sample that are within & 2 chart divisions

of each other denote good reproducibility within the data.

The chemicals used and the TC values obtained are given in the

results and discussion section.

77

Both stock solutions and treated samples were tested to

observe total carbon reduction with treatment.

Total carbon testing was performed on the following samples:

Acid Dye Mixture - Acid Blue 277, Acid Red 361 and Acid Orange 15 mg/l stock solution and 25 mg/l solutions treated at 50, 150, 250 'and 350 mg/l iron addition.

Acid Dye Mixture - Acid Blue 277, Acid Red 361 and Acid Orange 25 mg/l stock solution and 50 mg/l solutions treated at 50, 150, 250 and 350 mg/l iron addition.

Distilled Water run at 0, 50, 150, 250 and 350 mg/l iron addition with polymer addition.

Acid Blue 40 25 mg/l stock solution and 25 mg/l solutions treated at 50, 150, 250 and 350 mg/l iron addition.

Stainblocker D - 0.6 g/1 stock solution and 0.6 g/1 stock solutions treated at 550 and 650 mg/l iron addition, two sets were tested, one with just settling (no polymer addition) and one with floccing.

Color Removal Study

A Varian Cary 219 spectrophotometer was used to perform the

color removal evaluation tests. Only dye samples were tested

as they are the major color contributors in textile

wastewater. In addition to the dye samples, distilled 'water

blanks were run through the Andco Treatment Process following

the selected procedures. In this case, the spectrophotometer

was used to detect color contribution from the iron

hydroxides. An attempt was made to subtract off this color

from dye color measurements obtained at the same iron

treatment levels.

Absorbance values were recorded at the principal

These wavelengths used in dye detection 410, 510 and 610 nm.

78

are the maximum absorbance wavelengths of yellow, red and blue

dyes respectively. Initial testing was performed on four

different dyes, Acid Blue 277, Acid Blue 40, Acid Red 361 and

Acid Orange 156. . Standards were prepared of each dye at 5

mg/l, 10 mg/l and 20 mg/l. Using the recorded absorbance

values, a linear regression was done by computer and formulas

were developed for each dye. The formulas can be used tc

calculate the existing concentration of any one of the four

dyes in a mixture given the absorptions at the three

wavelengths. This is very useful in observing the individual

reduction percents of dyes in a mixture as they pass through

a treatment system. Alternatively, dye mixtures of the three

acid dyes were also prepared at 15, 25 and 50 mg/l

concentrations and formulas were developed to study overall

dye reduction (color removal) as opposed to individual dye

concentrations. The mixtures were run through the Andco Unit

and absorbance values were measured at 410, 510 and 610 nm.

These values were used in the previously calculated formulas

to determine remaining dye concentration in mg/l. The Acid

Blue 4 0 dye was treated separately, at 25 mg/l sample

concentration, and its own calibration curve and emation was

developed. Absorbance value's were measured at 610 nm, the

maximum absorbance for blue. The Acid Blue 40 dye was tested

individually to observe its treatment behavior with the Andco

Process because it has recently been added to the Interagency

Testing Committee Priority List [ 4 ] . Also, Procion Blue MX-

79

2G was treated in the Andco Unit at sample concentrations of

25 and 50 mg/l with varying iron levels, Lastly, through the

course of this study, several sets of distilled water blanks

were run through the Andco Unit for various comparisons of

iron color contribution. Although some of the iron levels

used in treatment varied from lotto lot, the distilled water

lots were compared to check reproducibility of iron color,

Dvebath Water Reuse Studv

In recent years the southeast has experienced record

setting droughts. Textile industries in the southeast have

experienced strains on production as they have been plagued

with water restrictions and higher pollution standards. Water

conservation and reuse pethods for all aspects of the textile

industry are being developed and put to practical use, One

possibility existing with the Andco Treatment Process is that

the treated water has reuse potential. Chemical removal with

the Andco Process ranges from about 50-100% depending on the

type or combination, as well as, the concentration of

chemicals present. Any residuai chemicals, iron or polymer

remaining in the treated water may have a significant effect

on the dyeability of process materials. This study

investigated the effects of dyeing materials with exhausted

dyebath water treated with the Andco Process. The iron

treatment levels were varied to study variation in dye uptake

and shade matching with control samples dyed in tapwater.

80

Also, some dyeings used treated dyebath water containing

residual dyes, stainblocker chemicals and other- auxiliary

chemicals, these samples were ref erred to as ltspikedll samples.

During the residual dyebath water testing, the absorbance

spectrophotometer was employed to test absorbances of the

exhausted dyebaths. The absorbances were compared to see if

the material samples had taken up equal amounts of dye from

the dyebaths. However, in most cases the exhausted dyebath

was still so concentrated with dye as to be off scale. At

this point, the most likely alternative for testing dyeing

similarity was the colorimeter. This method is more accurate,

in any case, for the type of test to be done. That is,

reflectance measurement of the material samples would be a

more accurate and direct method of color measurement than

measuring residual dyebath color. After all, dye removed from

the bath may come off the sample during rinsing. Color

measurements using an ACS Spectro Sensor I1 spectrophotometer

were taken of the samples to determine how close the

experimental materials were in shade to the standard materials

dyed in untreated tap water. Procedure *.

Two acid dyes used previbusly in this study were used for

the dyebath reuse tests, as well as one direct dye. The three

dyes were Acid Blue 277, Acid Red 361 and Procion Red MX-5B

RR-2. Stock solutions of 1.02 g/1 were prepared and 20 mg/l

solutions of each were treated with the Andco Process at

81

various iron levels. The Acid Blue 277 was treated at 197

mg/l and 283 mg/l of iron; 1800 ml samples were taken at each

iron level for the first dyeing set. A second sample of A.B.

277 was treated at'121, 207 and 287 mg/l of iron and 20 mg/l

dye concentration. Again, 1800 ml samples were taken and the

treated water was used in the second set of A.B. 277 dyeings.

The Acid Red 361 and Procion Red MX-5B RR-2 were treated at

121, 207 and 287 mg/l of iron and 1800 ml samples were taken

at each iron level. An identical sample of A.R. 361 as above

was treated at the same iron levels and the treated water was

used in the second set of A.R. 361 dyeings. Also, 100 ml

samples of each 20 mg/l dye solution were taken before

treatment as references and for absorption measurement.

Absorption data was collected on all sample stock solutions

and iron level samples at 410, 510 and 610 nm.

The Beer-Lambert equation was used to calculate the

concentration of dye present after treatment at each iron

level. The equation is given as follows:

A = abc (2-3)

Where A is the absorbance, a is the absorptivity coefficient

at a given wavelength, b is the path length (cm) and c is the

concentration of the sample. The lat value was calculated

using the absorbance value of the stock solution for each

sample at its primary absorbance wavelength which corresponds

to 510 nm for the red dyes and 610 nm for the blue dye. The

82

use of a single data point from one concentration to calculate

the absorptivity is not a standard procedure. A -chemical Is

absorbance may not increase linearly with concentration so a

single measurement at one concentration mat not be valid. ..

Therefore, there is a considerable error that may be

introduced in this particular experiment, After realizing the

procedural error, an attempt was made to determine if the

absorptivities calculated in this experiment were valid.

Solutions of 3, 10 and 2 0 mg/l of both the red and blue dyes

were prepared respectively and their absorbance values

recorded at the forementioned wavelengths. The absorptivities

were calculated using a computer generated linear regression.

The calculated absorptivities were then compared with the

original absorptivities to see how much the initial

measurement varied and how it affected the calcultions that

followed. It was found that the error in the original

measurement was off by approximately 0.1 to 0.2% which was

considered to be negligible. Given the measured absorbance

values for the treated water and using the less precisely

calculated l a o value, t h e existing concentration of residiral

dye was calculated. Knowing the existing resldual dye

concentration of the treated water allowed the development of

a reconstituted dyebath which incorporated the residual dye

with the add:ition of fresh dye and auxiliary chemicals. Nylon

6,6 270'F Superba heatset carpet yarn (5.0 t 0. lg) was used in

the experiments using the acid dyes, while scoured cotton

83

fabric (10.0 2 0.1s) was used with the Procion dye. All

dyeings were carried out in 600 ml beakers started at 60 C , with heating to 100 C and dyed for 30 minutes with stirring.

The samples were ‘.‘removed, rinsed with tapwater and labeled.

All nylon yarn dyeings had a p H of 10.2 except those that were

spiked, which had a dyebath p H of 10.4. The cotton dyeings

had a p H of 7.4. Also, all volumes were measured with

graduated pipets and/or volumetric flasks to increase volume

accuracy; however, the small dyebaths used were by nature,

very susceptible to large variance in final chemical

concentration. Even a small drop of unintentionally added

chemical or dye can greatly affect the final dyebath

concentration. Full-scale dyebaths would have been affected

much less by small differences in chemical addibon and would

have produced much more conclusive information about dyebath

reuse; however, the Andco ttM1t cell was not practical for use

in large scale testing due to its small size. The small-scale

beaker dyeings were used as an indicator to determine if

further testing and/or full-scale dyeing tests should be

pursued. The following dyebaths were prepared:

A . B . 277 Dyeinq #1

Control Dvebath.

30 : 1 Liquor Ratio for 5.0 + 0.1 g nylon 6,6 Superba

270°F heatset yarn = 150.0 total volume

4 . 0 % ammonium sulfate owf = 0.2 g = 10.0 ml of 2 0 g/1

stock soh.

84

1.0% ammonium hydroxide (28%) owf = 1.5 ml (1.0% X

150ml)

Tapwater to make 150 ml volume (= 88.5 ml)

Residual Dve.Content Calculation*. ..

Iron Level

Sample mg/l

197 mg/l : 0.0246 = (0.0095) (1 cm) (c)

c = 2.59 mg/l -->0.003 mg/ml --> .

0.003 mg/m1(88.5 ml treated water) = 0.30 mg

283 mg/l : -0221 = (0.0095) (1 cm) (c)

c = 2.33 mg/l - ->0.002 mg/ml -->

0.002 mg/m1(88.5 ml treated water) = 0.20 mg

Dve Rewired - Residual Dve = Needed Dye.

197 mg/l :

50.0 mg (=50.0 ml A . B . 277 1.0 g/1 stock soln.) - 0.30mg = 49.7 mg (=49.7 ml A.B. 277 l.Og/l stock soln.)

.

Also, 0.3 ml tapwater to make 50.0 ml dye volume.

283 mg/l :

5 0 . 0 mg (=50.0 ml A . B . 277 1.0 g/1 stock soln.) - 0.20mg = 49.8 mg (49.8 ml A . B . 277 1.0 g/l. stock soln.)

Also, 0.2 ml tapwater to make 50.0 ml dye voltrme.

* The more precisely calculated absorptivity value was 0.0076. Using this value in the above calculations resulted

in only a 022% difference in dye volumes. Consequently, the

small error in absorptivity calculation had little effect on

this experiment.

85

A.R. 361 Dveins #2

Control Dvebath.

30:l Liquor Ratio f o r 5.0 2 0.lg nylon 6,6 Superba 270'F

heatset yarn.= 150 ml

4.0% ammonium sulfate owf = 10 ml

1.0% ammonium hydroxide owf 1.5ml

1.0% dye owf = 50 ml

Tapwater to make 150 ml volume (88.5 ml tapwater)

Residual Dye Content Calculation *. Iron Level : A = abc

..

Sample

121 mg/l

207 mg/l

287 mg/l

: 0.0908 = 0.0103 (1 cm)(c)

c = 8.8 mg/l ---> 0.0088mg/ml --- >

0.0088 mg/m1(88.5 ml) = 0.8 mg

: 0.0718 = 0.0103 (1 cm)(c)

c = 7.0 mg/l ---> 0.0070 mg/l --- >

0.0070 mg/m1(88.5 ml) = 0.6 mg

: 0.0824 = 0.0103 (1 cm) (c)

c = 8.0 mg/l ---> 0.0080 mg/ml --- >

0.0080 mg/m1(88.5 mlj = 0.3 mg

Dye Rewired - Residual Dye = Needed Dye.

121 m g / l :

50 mg ( = 50 ml of AR 361 1.0 g/1 stock soln.) - 0.8 mg = 49.2Img (= 49.2 ml of AR 361 1.0 g/1 stock soln.)

Also, 0.8 ml of tapwater to make 50.0 ml dye volume

207 mg/l :

86

50 mg - 0.6 mg = 4 9 . 4 mg (=49.4 ml)


287 mg/l :

50 mg - 0.7 mg = 4 9 . 3 mg (=49 .3 ml)


* The more precisely calculated absorptivity value was 0.0119. Using this value in the above calculations resulted

in only a 0.2% difference in dye volumes. Consequently, the

small error in absorptivity had little effect on this

experiment.

..

Sgiked Dvebath.

The three iron level treated samples 121, 207, and 287

mg/l for A.R. 361 were each used in a spiked dyeing. Also,

for this set of dyeings, residual dye content was not taken

into consideration. The dyebath consisted of the following:

- ,

5 0 . 0 ml A.R. 361 1.0 g/1 stock solution

10.0 ml (+ 1.0 ml additional) ammonium sulfate = 11.0 ml

1.5 ml (+ 0.5 ml additional) ammonium hydroxide = 2.0 ml

25 ml Stainblocker "Btl (15 g/1 stock solution>)

Treated water to make 150 ml total volume (62.5 ml)

A.B. 277/A.R. 361 Purple Mixture Dveinq

Control Dvebath.

30:l Liquor Ratio = 150 ml total volume

4 . 0 % ammonium sulfate owf = 10 ml

1.0% ammonium hydroxide owf = 1.5 ml

87

1.0% dye owf = 50 ml (35 ml AR 361 1.0 g/1 stock solution

+ 15 ml AB 277 1.0 g/1 stock solution)

Tapwater to make 150 ml volume (88.5 ml tapwater)

Treated Water Mixture.

The 197 mg/l A . B . 277 and 207 mg/l A.R. 361 iron level

treated samples were mixed in equal volumes of 44.25 ml to

total the 88.5 ml water requirement. The 283 mg/l A . B . 277

and 287 mg/l A.R. 361 iron level treated samples were mixed

in the above proportions. The forementioned iron level

treated samples were mixed in the given manner because their

iron addition levels were considered to be approximately the

same. Previous calculations showed that the residual dye

contents were 0.0026 and 0.0023 mg/ml for A.B. 277 197 mg/l

and 283 mg/l treated water samples respectively, and 0.0069

and 0.0080 mg/l for A.R. 361 207 mg/l and 287 mg/l treated

water samples respectively.

.

Residual Dve Content Calculation*.

A . B . 277 197 mg/l: 0.0026 mg/1(44.25 ml) = 0.1 mg

--> 15 mg (715 ml AB 277 l.Og/l stock soln.) - 0.1 mg =

14.9 mg (=14.9 ml AB 277 1.0 g/l stock soinj

AR 361 207 mg/l: 0.0069 mg/1(44.25 ml) = 0.3 mg

--> 35 mg (=35 ml AR 361 1.0 g/1 stock soln) - 0.3 mg =

34.7 mg (=34.7 ml A.R. 361 1.0 g/1 stock soln)

AB 277'283 mg/l: 0.0023 mg/1(44.25 ml) = 0.1 mg

--> 15 mg (=15 ml AB 277 1.0 g/1 stock soln) - 0.1 mg =

14.9 mg (=14.9 ml A . B . 277 1.0 g/1 stock soln)

88

AR 361 287 mg/l: ).0080 mg/1(44.25 ml) = 0.4 mg .

--> 35 mg (=35 ml AR 361 1.0 g/1 stock soln) -- 0.4 mg =

34.6 mg (=34.6 ml AR 361 1.0 g/1 stock s o h )

For the AB 277 197 mg/l : A.R. 361 207 mg/l mixture,

total dye required = 34,7ml(AR 361) - 14.9ml(AB 277)

= 49.6 ml, + 0.4 ml tapwater For the A.B. 277 283 mg/l : A.R. 361 287 mg/l mixture,

total dye required = 34.6ml(A.R. 361) - 14.9ml(A.B. 277)

= 49.5 ml, + 0.5 ml tapwater

* The more precisely calculated absorptivity for A.R. 361

was 0.0119 as compared to the determined value of 0.0103. The

final difference in the dye volumes calculated for the two

absorptivity values was less than 0.1%. This small difference

in dye volumes was considered negligible. Thus, the error in

the procedure for determining the absorptivity value did not

result in a great error in the experiment.

.

Procion Red MX-5B Dveinq

Control Dvebath.

40:l Liquor Ratio for 10.0 g of scoured cotton fabric =

400 mi total volume

20% NaCl owf = 2.0g

1.0% dye owf = 0.1 g = 100 ml of Procion Red l.Og/l

stock solution

Tapwater to make 400 ml volume (300 ml of tapwater)

89

Residual Dye Content*.

Iron Level :

Sample

121 mg/l

207 mg/l

287A mg/l

287B mg/l

.

A = abc

0.0360 = 0.02 (1 cm) (c)

c = 1.8 mg/l ---> 0.002 mg/ml --- >

0.002 mg/m1(300 ml) = 0.60 mg

0.0526 = 0.02 (1 cm) (c)

c = 2.63 mg/l ---> 0.003 mg/ml --- >

0.003 mg/m1(300 ml) = 0.90 mg

0.0460 = 0.02 (1 cm) (c)

c = 2.3 mg/l ---> 0.002 mg/ml --- >

0.002 mg/m1(300 ml) = 0.60 mg

0.0540 = 0.02 (1 cm) (c)

'- c = 2.7 mg/l ---> 0.003 mg/ml -->

0.003 mg/m1(300 ml) = 0.90 mg

Dye Recruired - Residual Dve = Needed Dye.

121 mg/l:

100 mg (=lo0 ml of Procion Red 1.0 g/1 stock soh) - 0.6 mg = 99.4 mg (=99.4 ml of Procion Red 1.0 g/1

stock SOPXIj w i t h 9.6 nl tapwater = 100 AI dye volume

207 mg/l:

100 mg - 0.9 mg = 99';l mg (=99.1 ml) with 0.9 ml H20

287A mg/l:

100 mg - 0.6 mg = 99.4 ml (=99.4 ml) with 0.6 ml H20

287B mg/l:

100 mg - 0.9 mg = 99.1 mg (=99.1 ml) with 0.9 ml H20

90

* The precise absorbance was not calculated for this experiment. Hence, the error in the less precisely determined

absorbance was not known, but it was believed to be very

small ,

A.B. 277 Dveina #2

Control Dvebath.

30:l Liquor Ratio for 5 . 0 2 0.1 g nylon 6,6 Superba

270oF heatset yarn = 150 ml total volume.

4 . 0 % ammonium sulfate owf = 10 ml

1.0% ammonium hydroxide = 1.5 ml

1.0% dye owf = 50 m g = 50 ml

Tapwater to make 150 ml volume ( 8 8 . 5 ml tapwater)

Unspiked Dvebath.

Same as the control except that 8 8 . 5 ml of treated water

was used instead of tapwater.

not taken into consideration.

Also, residual dye content was

Dyebaths were prepared for 121,

207, and 287 mg/l iron level treated samples of A.B.

mg/l stock sample for a total of three unspiked samples,

277 20

Spiked Dvebath:

The spiked dyebaths used t'ne contol dyebath famulation

with the addition of some auxiliary and stahblocker

chemicals. The additional chemicals were addedto the dyebath

with water that had already gone through the treatment

process. If the chemicals had been added before treatment,

the removal levels of each chemical treated would have been

extremely complicated to determine. By adding the chemicals

91

after treatment, exact concentrations of each was known and

their affects on the dyeing were simplier to determine. It

was estimated that a mixed wastestream containing a 1.0 g/1

stainblocker concentration would contain approximately 0.3-

0.5 g/1 residual concentration of stainblocker after treatment

by the Andco Process. For this reason, each spiked sample

contained 25.0 ml of 15 g/1 stainblocker lrBlt stock solution

(0.375 9). An additional 1.0 ml of ammonium sulfate and 0.5

ml of ammonium hydroxide was added to simulate residual

process chemicals in the treated dyebath water. Again,

dyebaths were prepared for the 121, 207, and 287 mg/l iron

level treated samples.

The spiked dyebath contained the following:

50.0 ml of A . B . 277 1.0 g/1 stock solution

10.0 ml ( + 1.0 ml additional) ammonium sulfate = 11.0 ml

1.5 ml ( + 0.5 ml additional) ammonium hydroxide = 2.0 ml

25.0 ml of Stainblocker llB1l (from a 15 g/1 stock solution)

Treated water to make 150.0 ml total volume (62.5 ml)

A.R. 361 Dveins #2

The A.R. 351 dyeing #2 consisted of one con t ro l samples

three unspiked samples and three spiked samples corresponding

to 121, 207 and 287 mg/l iron level treated water samples.

The procedure and dyebaths were exactly the same as for the

A . B . 277 dyeing #2. Again, residual dye content was not taken

into consideration.

. . I , . - . , - . .. ... . - . . I . . , ’. . , -;” ’-. . . . , .

92

Color Measurement Theorv

Instrumental assessment of color (hue), saturation and

lightness components is based on the same principles as human

assessment, Both evaluate radiant energy reflected off an ..

object or emanating from a source. The instrumental

assessment converts detected radiant energy into quantifiable

numerical data in a manner similar to the way the human brain

converts radiant energy into visual perception.

For this study, visual comparison was used because the

trained human eye is still an incredibly sensitive method for

distinguishing differences between samples, However, the

visual observation was limited to the assessment of large

differences in color and shade because the observer did not

have a trained eye (in the textile industry and other

industries there are people specifically trained to

distinguish between very small differences in color) ,

i

However, convert human visualization into quatifiable

. differences an instrumental method is required. An ACS

Spectro Sensor II using the Chroma Calc Color Lab program was

employed in addition to visual observation. A schematic of

an ACS Spectro Sensor type colorimeter is shown in’Figure 2-

4 . The sample is placed in front of the sample port where it

is illuminated with light from the tungsten lamp. The

reflectancezfrom the sample passes through a rotating filter

disc to a photo detector. An amplifier receives the signal

and sends it to an IBM PS/2 digital computer system which

93

ANALOG To DIGITAL

CONVERTER - --

..

..

DATA TO COMPUTER

-

ACS SPECTRO-SENSOR SCHEMATIC

Figure 2-4 Schematic of an ACS SpectroSensor Colorimeter.

. - - . . , . . , .

94

computes the measurement data. The CIE LAB measurement system

was used to calculate the data given in the results section.

The subject of colorimetry is very extensive and many other

methods like the CZE system have been developed, each with its

own advantages. However, for the scope of this research only

the CIE LAB 1976 method was employed.

..

The CIE WIB system was developed by the Commission

Internationale de 1'Eclairage (CIE) as a method to calculate

color differences between two samples. In the CIE LAB system

the a and b values represent color differences in redness-

greenness and yellowness-blueness respectively while the L

value represents the lightness-darkness. The total color

difference is given by DE ( the change in E between two

samples), The &7 Yn', and 2, values represent tristimulus

values of the standard illwinant (typically A or DC5 CIE

standard il1uminants)under which the samples are prepared.

A set of sample calculations is given f o r comparison of two

samples in Figure 2-5. In general, it is found that dye

aciditfion tends to increase absorbance or decrease reflectance

while reducing dye concentration decreases absorbance,

therefore, increasing reflectance values. The matedal sample

itself has a great effect on measured values. Sample yarns

with many voids tend to scatter light increasing reflectance

values. Increasing the diameter of a fiber reduces light

scattering by decreasing the surface to volume ratio, this

increases absorbance therefore reducing reflectence.

95

Samrsle 1 Samrsle 2 &< Standard Illuminant

X = 6.94 X = 7.69 Y = 7.19 Y = 8.24 Z = 7.42 z = 7.93

X, = 94.825

Z, = 107.381 Y , = 100

L* = 116 L, = 116 Lz = 116 DL = 34.47 - 32.23 = 2.84

( Y / Y , ) ’ l 3 - 16 (7.19/100)1’3 - 16 = 32.23 (8.24/100)1’3 - 16 = 34.47

a* = 500 [ ( X / % ) l l 3 - 16 = 34.47 a, = 500 [(6.94/94.825)lI3 - (7.19/100.0~~~~] = 1.23 a2 = 500 [(7.96/94.825)’13 - (8.24/100)” J = 1.35

b* = 200 (Y/Y,) - jz/zn) J b, = 200 [ (7.19/100)1 - (7.19/107.381)1’3] = 1.09 b2 = 200 [ (8.24/100)1’3 - (7.93/107.381)1’3J = 3.12 DB = 3.12 - 1.09 = 2.03

D, = 1.35 - 1.23 = 0.08

C = [(a)2 + (b)2]1/2 C, = [(1.23)2 + (1.0939)2a1’2 = 1.65 C2 = [(1.35)2 + (3.12)2J1’ = 3.39 DC = 3.39 - 1.65 = 1.74

DE = [(DL)2 + (Da)2 + (Db)’]1/2 DE = [(3.02)2 + (.08)2 + (2.03)2]1/2 = 3.02

DH = [ (DE)2 - (0Ll2 - iDC)2]1’2 DH = [(3.02)’ - (2.24) - (1.75)2]1’2 = 1.04

Figure 2-5 CIE LAB 1976 equations used to quantify sample differences. D = Difference

96

Each of the samples dyed in the recycled water was

measured against the control sample which was dyed by the

conventional method. Yarn samples were tested after mounting

on white poster. board bys wrapping the surface with

approximately 2 x 2 inches of yarn. The cotton fabric samples

that were used in the Procion Red dyeing did not require

mounting and were placed directly in the porthole for color

measurement. Each sample was scanned from 400-700 nm. The

%Reflectance vs. Wavelength was obtained for each sample and

compared to see how much the samples dyed conventionally

varied with samples dyed alternatively with treated water.

This is very important because visual inspection is limited

to the color sensitivity of the eye and the ability to

distinguish between v e b minute changes in color or depth of

shade. Also, the light source used w i l l change the color

perception. The ACS Spectro Sensor I1 spectrophotometer has

the ability to provide color differences in terms of

quantifiable numerical data. Also, the differences in

lightness, saturation, and hue were measured between the

treated water samples and the control samples.

The Mechanism of Electrochemical Color Removal

The results collected in the color removal study showed

excellent color removal and in the later study on dye water

reuse results collected indicated promising reuse

capabilities. However, one concern remained - how was the color being removed? It has been suggested that the dye

97

molecules may be removed by adsorption onto the iron matrix

created as the ferrous hydroxide precipitates. The ferric

hydroxide exists in an octahedral form, forming a ladder type

matrix with other: molecules of ferric hydroxide [36]. Part

of the color removal process may involve the dye molecule

adsorbing onto this matrix by both electrostatic attraction

and physical entrapment (363. Also, the dye actually may be

complexing with the ferrous hydroxide forming ionic bonds.

However, because the reaction within the treatment cell is a

reductive process (ie hydrogen gas is produced), it is

possible that the some dye molecules are degraded by a

reduction mechanism. Particular concern is placed on the

reactions of acid dyes with azo bonds which are susceptible

to reduction [16]. The electrochemical treatment involves the

production of ferrous iron Fe” which is very unstable and

tends to quickly oxidize to ferric iron Fd3. In the treatment

unit the azo bond can act as an electron acceptor obtaining

electrons from Fe” as it oxidizes to Fe+3. Using azobenzene

as an example, upon accepting 2 e- and 2H+, hydrazobenzene is

forned, and under the hi3hly reductive environment of the

treatment system with large electron availability.from the

continual production and oxidation of ferrous iron, the

hydrazobenzene would likely be reduced further to two

molecules of aniline [16]. Generally, aniline is only

produced when ortho-para activating groups like -OH or ether

groups and other amines are present on the ring making the azo

98

bond more susceptible to complete reduction [16]. However,

given the highly reductive environment existing in the

treatment cell, it is highly likely that aniline is produced.

The aniline is veky susceptible to air oxidation, oxidizing

to various products like nitrobenzene, azobenzene, and the

aniline can even be oxidized back to azobenzene [16]. Because

the treated water is continually recirculated through the

machine, the treated solution is exposed to air which promotes

further oxidation. For this reason it seems reasonable to

assume that if aniline is produced, that it is also likely

that some of its oxidation products are also present in the

treated sample. If such degradation products are produced,

a dual system using the Andco Process followed by oxidative

aerobic sludge digestion may reduce any threat to man or the

environment by further oxidizing the reduction products,

Lastly, color removal can also take place if some of the

substituents which determine the color of the dye are altered

in some manner, Examples of substituent groups are NO,, NO,

N=N and CO groups. Other chemical groups .. which impart-dyeing

properties to a colored substance and intensify the action of

the other color contributing substituents are called

auxochromes. They are usually weakly salt forming substances:

examples of auxochromes are SO,-Na+ and COO-Na+. The absorption

spectra are laffected by acid, base and changes in solvent.

Isomerism, tautomerism and transitions between electronic

states also affect absorption spectra. A great effort can be

99

made to obtain a pure chemical to study its spectra, but the

presence of isomers can cause differences in spectra compared

to that of an isomerically pure chemical. This is because the

spectrophotometer ‘:is measuring the absorption of light by a

chemical species which is raised to a state of higher energy

[ 3 4 ] . The energy, angle and strain on a given bond may affect

how it absorbs light energy. This is why isomers of the same

chemical may produce spectra with some absorption differences

1 3 4 1

Of course, the Andco Process may remove color by any one

of the above processes or any combination of the above. An

attempt was made to determine if dyes were removed totally by

adsorption or by another process or combination of the two.

It was determined by visual observation of the residual iron

sludge, that some amount of adsorption was likely taking

place. In some cases dye color was observed to increase in

the treated water if the water was not removed from the beaker

shortly after the flocculation procedure. In one case a blue

food dye contained in the sludge of a treated sample was

observed to migrate out of the sludge back into the treated

effluent over a period of about 2 4 hours.

To determine whether 3r not processes other than

adsorption were taking place, it was suggested that high

performance ,‘liquid chromotography (HPLC) be used. HPLC has

the ability to separate different chemical species in a

mixture. Each species has its own characteristic retention

100

time and peak height for a given solvent and column system

allowing it to be compared with standards to confirm its

identity. This method would allow a more detailed elucidation

of exactly what dye degradation products are produced - if any. However, due to limited time a detailed study of dye

degradation products using HPLC was not possible and a

quicker, but more general method of analysis was employed.

Absorption spectrophotometry was used to observe the change

in characteristic absorption peaks of the treated samples as

an indication of dye molecule alteration. This method is

sufficient to determine if dye molecule alteration is

occurring and to give a general indication of what degradation

products might be produced. However, specific and decisive

information cannot be accurately determined, as many of the

degradation products have absorption peaks that overlap.

Several sets of absorption experiments were performed using

the Cary 219 absorption spectrophotometer.

..

The following samples were treated with the

elect'rochemical treatment process:

1) Acid Blue 277 at 20 mg/l solution concentration

with 121, 207, and 287 mg/l iron treatlnent

levels.

2) FD&C Yellow # 5 food dye at 30 m g / l solution

concentration with 151, 237, and 337 mg/l iron

treatment levels.

101

3) FD&C Blue #2 food dye at 28 mg/l solution

concentration with 151, 237, and 337 mg/l iron

treatment levels,

4) Azob&zene at 34 mg/l solution concentration

in approximately 3.5% methanol/water at 154 , 302 ,

and 345 mg/l iron treatment levels.

All samples were prepared in the following manner.

Sample volumes of 1800 ml were taken; the pH was adjusted to

9.0-9.1; the samples were flocculated with the 0.2% polymer

solution (about 5 ml); and, then, the samples were filtered

through Pyrex glass wool into storage bottles. Next, each

sample was p H adjusted to 6.5 to reduce the solubility of

carbonate, and each was bubbled with pure oxygen for 3-5

minutes to oxidize any.residua1 soluble ferrous Fe” to ferric

Fe+3. This would reduce errors in absorbance measurement

caused by the presence of FeiZ and carbonate, The samples were

then filtered a second time with Pyrex glass wool before

taking any absorbance measurements.

The structures of FD&C Yellow #5, FD&C Blue #2, and

azobenzene are given in Figure 2-6. The structure of A . B . 277

is proprietary and has not been released. As a result of

this, no prediction of the altered products was possible, only

observation of spectral changes was carried out. A l s o , the

A . B . 277 is a commercial textile dye of unknown purity so the

changes in solution may be masked by the existence of

impurities, which have their own absorptions at characteristic

102

F i g u r e 2-6 S t r u c t u r e s f o r (A) FD&C Y e l l o w 95, (B) FD&C B l u e #2 , and (C) Azobenzene.

103

wavelengths. For this reason, food dyes of high purity

(approximately 9 5 % ) were obtained. The selection of the

yellow and blue dyes .. was based on their structures. The

yellow dye had an'azo bond and was selected because the azo

bond is frequently found in textile dyes. The blue dye had

a carbon-carbon double bond and was selected to see how it

behaved in comparison to the azo bonded yellow dye. To

further study the azo bond, azobenzene was selected as a model

compound. The azobenzene was 9 6 . 7 % pure and was treated in

a 3.5 % methanol/water solution to achieve acceptible

solubility of the azobenzene.

Color removal would indicate either removal by

adsorption/complexing or by destruction/alteration of the azo

bond. If the color removal was accompanied by corresponding

removal in the aromatic region of the spectra, then adsorption

9

would seem the likely mechanism for color removal. However,

color removal accompanied by a smaller decrease in absorbance

in the aromatic region would indicate some type of dye

molecule alteration, as the actual chemical content of the

solution may still be present, only not producing color due

to alteration of the chromophore.

In addition to the specba run on the treated azobenzene

samples and its standards, a spectrum of dilute aniline was

also obtained. Lastly, part of the azobenzene control stock

solution (about 50 ml of 34 mg/l stock solution) was degraded

with 1.0 g of sodium hydrosulfite, and a spectrum was recorded

104

for comparison with the stock solution, the aniline and the

treated samples. Also, for each sample of dye and azobenzene,

lower concentrations of 3 and 10 mg/l were prepared. _.

Additionally, concentrations of 20, 30, 30, and 35 mg/l

corresponding to the approximate concentrations of the control

samples for A.B. 277, Food Yellow #5, Food Blue #2, and

azobenzene, respectively, were prepared, Spectra of each were

obtained to calculate the absorptivity values at the given

selected wavelengths and to simulate how spectra would appear

if the dye chemical content was actually removed with no

alterations.

Spectra were measured from 195 to 622 nm for A.B. 277,

195 to 618 nm for FD&C Food Blue #2, 195 to 520 nm for FD&C

Food Yellow #5, and 195 to 555 nm for azobenzene. The scan

rate for all spectra was 0.5 nm/sec with a 1.0 second period.

The ABS range was 0-2 for each sample except for the A.B. 277

which was 0-1. Absorptivity values were calculated at

wavelengths of interest by using the absorbance values for

each of’ the three different concentrations prepared of each

sample. The Sadtler Handbook of Ultraviolet Spectra [ 3 3 3 was

used to select wavelengths of interest. Values for absorption

maxima of possible dye alteration products were obtained from

this source.

reduce degradation.

All samples were refrigerated between tests to

105

CHAPTER I11

RESULTS AND DISCUSSION

Chemical Oxvsen Demand Reduction

One of the purposes of this section was to determine how

effectively the electrochemical treatment process reduced COD

levels for the auxiliaries involved in dyeing and the

stainblocking chemicals recently introduced to the textile

industry. Throughout the experiments in this section, three

types of COD tests were used and referred to as high, medium

and low level tests. These simply corresponded to the

strength of the titrants used for each chemical tested.

Chemicals with a high COD content (up to 1000 mg/l COD)

required the use of high strength titrants, while medium range

chemicals (up to 500 mg/l COD) used titrants with half the

strength of the high level tests. Dyes had low COD values and

so low strength titrants had to be used to increase volume

accuracy. Details on the COD experimentation are given in the

experimental section (Chapter 11).

Stainblocker Chemicals

During experimentation it was found that COD values were

reduced anywhere from 25% to 100% depending on the chemical

being tested and the iron treatment level used. Stainblocker

chemicals generally had a maximum COD reduction of 80-90%.

106

Alternatively, dye COD reduction was less well defined because

the dyes had such low COD'S to begin with compared to the

stainblockers. The low values added to the error because they

approached background levels-associated with distilled water

blanks. The stainblockers on the other hand, were usually

easy to test with consistent and expected COD values. Table

..

3-1 shows the COD test values in mg/l and

for the Stainblocker rtAtt formulation.

0.1, 0.3, 0.6 and 1.0 g/1 were tested for

the percent removal

Stock solutions of

COD values and were

found to increase linearly with concentration. Removal levels

for the 0.6 g/1 stock solution'at 550 and 650 mg/l were

slightly higher than the corresponding 1.0 g/1 samples. It

was observed that increasing the iron addition from 550 to 650

Iron mg/l did not significantly change removal levels.

addition levels less than 550 mg/l would not floc for unknown'

reasons so only treatment levels of 550 mg/l and 650 mg/l were

used. Although greater amounts of iron can be added, the

economics are prohibitive and sludge disposal costs increase.

Due to the additional strain on local POTWs from the

increasing CODs of the stainblocker chemicals, manufacturers

began to develop formulations with lower COD valugs. During

the course of experimentation one of the stainblocker

producers sent two additional lower COD formulations known as

ltBtt and ltCtt'for testing. It can be observed by comparing COD

values from Table 3-2 for Stainblocker t tBtt with the

Stainblocker trAtt values in Table 3-1 that initial COD values

107 - -

Table 3-1 COD values and percent removal values for Stainblocker Formulation tlAtt at 0.6 g/1 and 1.0 g/1 sample concentrations with increasing iron addition.

0.1 g/1 stock (0) 0.3 g/1 stock (0)

0.6 g/1 stock (0) Iron Level 5 5 0

( m g / l ) - 650

1.0 g/1 stock (0) 5 5 0 650

COD (mcr/l)

112 253

693 471 471

1158 840 859

32.0 32.0

-- 27.5 25.8

108

Table 3-2 COD values and percent removal values for Stainblocker Formulation lrBrr at 0.6 g/1 and 1.0 g/1 sample concentrations with increasing iron addition.

0.6 g/1 stock (0) 4 5 0 550

Iron Level 6 5 0

1.0 g/1 stock ( 0 ) 4 5 0 5 5 0 6 5 0

"/l)

COD (ms/l)

240 34 16 4 4

401 85 107 77

-- 85.8 93.3 81.7

-- 78.8 73.3 80.8

109

had been reduced by 65% for both the 0.6 and 1.0 g/1 stock

solutions. In addition, Stainblocker I I B I 1 unlike Stainblocker

I1A1@ flocced at 450 mg/l iron addition allowing for lower

treatment levels.. Furthermore, the new formulation yielded

higher removal values (Table 3-2) from 80 - 93%. Once again,

it was observed that an increase in iron level from 450 to 650

mg/ldid not significantly yield further removal. It appeared

as though once an optimal treatment level was reached, further

treatment accomplished little more than increasing treatment

costs and sludge production., The third sample tested, known

as formulation 18C11, had initial COD values reduced by only 49%

and 56% of the Stainblocker I1Al1 sample at 0.6 and 1.0 g/1

stock solutions respectively. Not only was initial COD

removal less than for Stainblocker l tBt l , but COD removal after

treatment was also less, Table 3-3 shows COD values and

percent removal for Stainblocker I1C1l. The COD values for the

0.6 g/1 sample were reduced roughly 74-79% while the 1.0 g/1

sample had poor removal at only 42-49%. The removal values

decreased with increasing iron addition past the optimum level

(450 m g / l ) , Given that removal. percent decreased only a few

percent, it seemed likely that the decrease in removal with

increased iron addition could be taken to be part of the error

within the COD test. That is, for all intents and purposes

COD values of 73 and 92 mg/l for instance, can be considered

to be essentially the same. The final stainblocker tested

was a stainblocker formulation referred to as Stainblocker

110

Table 3-3 COD values and percent removal values f o r Stainblocker Formulation rtCrt at 0.6 g/1 and 1.0 g/1 sample concentrations with increasing iron addition.

0.6 g/1 stock (0) 450 5 5 0

I ron L e v e l 650

1.0 g/l stock ( 0 ) 450 5 5 0 650

"/l)

353 73 73 92

508 260 270 293

-- 79.3 79.4 73.9

-- 48.8 46.8 42.3

111

t rDt t . Initial COD values as shown in Table 3-4 are slightly

lower than the lowest COD for formulation tlBtl. Once again,

removal values were highest for the 0.6 g/1 stock solution

sample ranging from 60-100%. The 1.0 g/1 stock solution

sample achieved removal values of only approximately 40-55%.

A special test was performed on the Stainblocker t lDtt 0.6 g/1

stock solution sample. One set of 550/650 mg/l treated

solutions was flocced with polymer addition, the other was

allowed to settle without polymer addition. The COD removal

percents were compared in Table 3-4 and it was observed that

the polymer flocced samples achieved significantly higher

removal levels nearly 20% greater than the unflocced samples.

The degree and quality of the floc and its settling quality

appeared to have significant effects on the degree of removal

of COD and color. The process was very p H sensitive and

samples had to be adjusted to pH 8.9 - 9.1 before polymer addition to achieve any flocculation at all. In some cases

no amount of pH adjustment or polymer addition would cause a

floc and those samples that did not floc were discarded as

they were not considered representative of successful

electrochemical treatment. Problems with flocculation seemed

to plague the laboratory scale tests, but these problems were

attributed to the small sample size and the limited time

available to optimize the system to each individual chemical.

It was observed near the end of the experimentation that

larger volume samples like those used in the dyebath water

112

Table 3-4

Iron Level ( m g / l )

. I

COD values and percent removal values fo r Stainblocker Formulation **Dlf at 0.6 g/1 and 1.0 g/1 sample concentrations with increasing iron addition. * Denotes sample in which no polymer was used to achieve a floc.

0.6 g/1 stock (0) * 5 5 0 * 6 5 0

5 5 0 6 5 0

1.0 g/1 stock (0) 550 650

COD (ms/l)

196 77 61

31 0

326 147 196

-- 60.7 68.9

84.2 100.0

-- 54.9 39.9

113

Table 3-5 COD values and percent removal values f o r Irgalev A, an auxiliary chemical, at 0.6 g/1 and 0.8 g/1 sample concentrations with increasing iron addition.

Iron Level (mg/l)

0.6 g/1 stock (0) 250 3 5 0 450 550 650

0.8 g/1 stock (0) 250 350 450 550 650

604 294 171 184 175 143

673 370 331 257 362 405

-- 50.0 71.6 69.6 71.0 76.3

45.1 49.1 61.9 46.2 40.0

114

Table 3-6

Iron Level “/l)

COD values and percent removal values for Guar Gum, an auxiliary chemical, at 0.3 g/1 sample concentration with increasing iron addition.

0.3 g/1 stock ( 0 ) 250 350 450 5 5 0 6 5 0

298 104 84 58 58 96

-- 65.2 71.7 80.7 80.7 67.8

115

reuse tests (volume = 1800 ml) flocced much easier than those

of the 500 ml volume size.

Auxiliarv Chemicals

A set of tests were run on Irgalev A anionic surfactant.

The CODs were very high at 600 mg/l COD for the 0.6 g/1 stock

solution and 673 mg/l COD for the 0.8 g/1 stock solutions.

A 0 . 9 g/1 sample was run but the sample would not floc and

much of the solids floated on the top. As shown in Table 3-

5 removal values were mostly consistent with approximately 70%

removal for the 0.6 g/1 stock solution sample and 40-60% for

the 0.8 g/1 stock solution. As in the past, the higher the

concentration of the stock, the lower the removal level

achieved. A sample of Guar Gum (a thickening agent) was run

at 0.3 g/1 and 0.6 g/1 stock solutions; however, the 0.6g/l

sample would not floc. A repeat test of the 0.6 g/1 sample

was conducted with the same results and had to be discarded.

Table 3-6 shows the COD values and respective removal percents

for the 0.3 g/l. Maximum removal was observed at 450-550 mg/l

iron addition giving roughly 81% removal.

Flocculation Polvmer Contribution To COD

In response to a concern that the polymer addition may

have been contributing to the sample COD, standards of

distilled water were treated at frequently used iron levels

with monitored polymer addition. A low level COD test was

performed and it was found that COD values were more or less

random from one iron level to another. Table 3-7 shows the

116

Table 3-7

Iron Level "/l)

COD values for distilled water blanks treated with the Andco Process, and the corresponding polymer quantities required to produce a floc.

5 0 150 2 5 0 3 5 0 450 5 5 0 650

Polymer (ml)

0.24 0.26 0.95 1.00 1.40 0.25 0.65

COD (ms/ll

4 0 0

109 0

23 26

1 1 7

distilled water samples’ COD values and it can be seen that

at the two highest polymer additions, the lower 1.0 ml

addition has a COD of roughly 110 mg/l while the higher

addition level, 1;4 ml, has a COD of zero. Questions still

remain on the nature of these distilled water samples, such

as whether or not the high COD values are caused by poor

flocculation or free polymer in solution. Poor flocculation

may result in the presence of more Fe” ferrous iron in

solution. This may also result in a contribution to COD as

Fe+2 oxidizes to Fe+3. Background distortion is not out of the

question as a cause of the random results, especially since

the low level COD test was used. The low level COD test

involves the use of diluted titrants used to increase the

volume accuracy when .testing chemicals with low chemical

oxygen demand values approaching the background error for the

test. In any case, the COD values for the polymer and iron

contribution should be negligible when high COD containing

chemicals like auxiliaries and stainblocker chemicals are

being tested.

Another method investigated for use in determining the

organic content of a sample was the TC - Total Carbon Analyzer. The detector measures carbon dioxide produced by

an organic, or inorganic carbon containing compounds upon

oxidation under extreme heat (1600OF) with units of mgC/1 , while chemical oxygen demand measures the oxygen necessary to

oxidize organics to CO, and H,O given in units of mgOJl.

118

Table 3-8 Average peak height, total carbon and percent removal values for Stainblocker Formulation rrDrl at 0.6 g/1 and 1.0 g/1 sample concentrations with increasing iron. * Denotes samples in which no polymer was used to achieve a floc.

Average Peak Heiqht

0.6 g/1 stock (0) 51.2

* 550 13.5 * 650 21.5

5 5 0 8.5 Iron Level 650 6.7

1.0 g/1 stock ( 0 ) 70.1 5 5 0 34.1 650 55.3

"1)

TC 0 88.6

1.2 19.7

-10 . 4 -14.6

132.4 48.9 98.1

98.6 77.8

> l o o > l o o -- 63.1 25.9

119

\

After CODs were tested for on Stainblocker oD1l, the same

sample was tested on a TC Analyzer. Table 3-8 shows the total

carbon in mgC/1 and the percent removal with increasing iron

addition. Samples were tested at 0.6 g/1 stock solution with

both flocced and settle samples, and at 1.0 g/1 with just

flocced samples. The settled 0 . 6 g/1 samples had very high

removal levels between 77-99% and the flocced samples measured

out below background levels indicating near 100% removal. The

1.0 g/1 stock solution had good removal at 550 mg/l iron

addition but that removal dropped to 26% when the iron

addition was increased to 650 mg/l. It was decided that this

method would be sufficient for future tests on high COD

materials like the stainblockers or auxiliary chemicals, but

would not be a wise choice for low COD materials whose

response tends to be obscured by background noise and CO,

naturally dissolved in water. The TC did support the COD

measurements on the Stainblocker llD1l including the observation

that polymer floccing increases organic reduction more than

settling alone as shown in Figure 3-8.

Color Removal Results

Dve COD And TC Test Results

During the beginning of this study, it was thought that

COD reduction in dye solutions would serve as an indicator of

actual dye removal and therefore color removal. However,

several attempts were made to adjust the COD test to

120

accurately determine the COD of

not very successful as the dyes

results were often masked in the

the dye solutions, this was

had such low COD values that

error range of the COD test.

The first set of ‘CODs run on dyes used the high level COD

test. The COD values and removal percents for the 25 mg/l and

50 mg/l acid dye mixtures (A0156, A R 3 6 1 , AB277) are shown in

Table 3-9. As can be seen, the numbers are scattered and

inconclusive, fluctuating and showing no linear relation with

increasing iron level as might be expected. The low level test

was employed to increase the volume accuracy of the test.

Samples of 25 mg/l and 50 mg/l Acid Red 361 were tested with

the low level COD test. The corresponding COD values in Table

3-10 showed improvement with less scattered results. The COD

was observed to increase with an increase in concentration as

expected and somewhat consistent reductions in COD were

observed at most iron levels. Polymer addition levels were

recorded to see if they had any effect on COD. Average

removals were in the 0-100% range for the 25 mg/l stock

solution and between 25 to 6.0% for the 50 mg/l stock solution.

Similar results were obtained from Procisn Blue MS-2G run at

25 mg/l and 50 mg/l sample concentrations. The amount of

polymer necessary to achieve a floc is given along with

corresponding COD values and percent removal for the Procion

Blue samples in Table 3-11. The polymer used appeared to have

no apparent bearing on the level of COD. The Procion Blue

sample at the higher concentration of 50 mg/l had the greatest

121

Table 3-9

I r o n Level

COD values and percent removal for the acid dye mixture at 25 (mg/l) and 50 (mg/l) sample concentrations with increasing iron addition.

25 (mg/l) stock ( 0 ) 50

150 250 350

"/l) 50 (mg/l) stock ( 0 )

50 150 250 350

93 27 89 0

85

40 566 89 85 0

70.8 4.2

100.0 8.3

-- + + +

100.0

122

Table 3-10 Required polymer (ml), COD values and percent removal values for A.R. 361 dye at 25 (mg/l) and 50 (mg/l) sample concentrations with increasing iron addition.

25 (mg/l) stock ( 0 ) 50

100 150 250

Iron Level 350 "/l) 450

50 (mg/l) stock ( 0 ) 50

100 150 250 350 450

Polvmer (ml)

-- 0.10 0.17 0.10 0.21 0.17 0.42

0.40 0.24 0.52 0.31 0.36 0.43

COD (ms/l)

10 0 2 6 2 12 0

102 ,69 94 75 43 74 67

-- loo. 0 80.0 40.0 80.0 +20.0 100.0

-- 32.4 7.8 26.5 57.8 27.5 34.3

123

. .

Table 3-11 Required polymer ( m l ) , COD values and percent removal values for Procion Blue MS-2G dye at 25 (mg/l) and 50 (mg/l) sample concentrations with increasing iron addition.

25 (mg/l) stock

Iron Level “/l)

50 (mg/l) stock

( 0 ) 50 100 150 250 350 450

( 0 ) 50 100 150 250 350 450

Polymer (ml)

-- 0.4 0.4 0.6 0.5 0.4 0.4

-- 0.4 0.6 0.6 0.7 0.5 0.5

COD (ms/l)

40 32 39 30 31 19 19

64 13 33 61 31 20 46

20.0 2.5 25.0 22.5 52.5 52.5

-- 79.7 48.4 4.7 51.6 68.8 28.1

124

removal ranging from 5 to 8 0 % while the lower concentration

of 25 mg/l had lesser removal from 3 to 50%. Removal levels

fluctuated among the different iron levels, with no one iron

level appearing to be significantly better than any other iron

level. Due to the inconsistency of the results obtained, the

use of the COD test for dyes was discontinued.

The total carbon test was attempted to see if it could

be applied to the dyes, but once again, the carbon content in

the dilute (25, 50 mg/l) solutions of the dyes was below the

background noise associated with the TC test. Values came out

negative for carbon content in samples, known to have carbon

content. Tables 3-12 and 3-13 show the scattered and negative

results obtained for the 25 mg/l and 50 mg/l acid dye mixtures

and the Acid Blue 40 25 mg/l test solution respectively. An

attempt was made to subtract off TC values obtained from the

distilled water blanks treated at corresponding iron levels

(TC ttBa). However, almost all values came out negative after

subtraction, even for samples known to have residual dye from

absorption measurements. For this reason, the "puret1 values

without blank subtraction for TC of the dyes are given under

TC "Atf. In any case, the TC appeared to increase after

treatment, possibly from polymer addition. Also, the treated

water churns as it recycles through the machine possibly

increasing dissolved gases such as 0, and CO,. The values used

for iron blank subtraction are given in Table 3-14. In

addition, a negative value was observed for untreated

125

Table 3-12 Average peak height and total carbon values A) before iron blank subtraction, B) after iron blank subtraction, for the acid dye mixture at 25 (mg/l) and 50 (mg/l) sample concentrations.

25 (mg/l) stock ( 0 ) 5 0

1 5 0 Iron Level 2 5 0

"1) 3 5 0

50 (mg/l) stock ( 0 ) 5 0

1 5 0 2 5 0 3 5 0

Average Peak TC "1) Heisht A B

--- 10.8 -5.2 16.6 8.4 -24.1 18.7 13.1 -19.3 13.5 0.4 -31.0 16.7 8.5 -17.5

--- 15.6 6.1 31.9 43.8 11.3 27.9 33.6 - 3.9 27.2 32.9 '1.6 8.3 -10.9 -23.4

126

Table 3-13 Average peak height and total carbon values A) before iron blank subtraction B) after iron blank subtraction, for A.B. 40 25 (mg/l) sample concentration.

Average Peak TC “1) Heicrht A B

--- 25 (mg/l) stock ( 0 ) 10.5 -5.9 50 18.5 12.8 -19.7

Iron Level 150 21.9 20.6 -16.9

350 17.0 9.3 -16.7 “/l) 250 17.0 9.3 -22 . 0

Table 3-14

I r o n Level “/l)

Average peak height and total carbon values fo r the distilled water iron blanks.

0 5 0

150 2 5 0 3 5 0

Average Peak H e i c r h t

8 . 8 14.0 16.2 13.5 11.2

Tc tm/ 1)

-10.3 2.3 7 . 4 1.2

- 4 . 2

128

distilled water. It was decided that this method would not

be a wise choice for low COD materials whose response tends

to be obscured by background noise and CO, naturally dissolved

in water. ..

Absomtion SDectroDhotometer Color Removal Results

The COD and TC tests did not provide a very clear picture

concerning dye removal. However, the absorption

spectrophotometer (Cary 219 model) turned out to be several

magnitudes greater in sensitivity to changes in dye

concentration (actually color concentration) as an indicator

of dye behavior with the Andco Process. The absorption tests

were used to determine color removal. The color removal could

represent actual dye removal, dye alteration or a combination

of the two. This topic was studied further in the fourth

study on the mechanism of dye removal in the Andco Process.

Preliminary absorbance data were collected at absorbance

wavelengths of 410, 510 and 610 nm for the dyes used in

testing as shown in Table A-1 of the Appendices. Four

principal acid dyes were tested - CI Acid Red 361, CI Acid Blue 277, CI Acid Orange 156 and CI Acid Blue 4 0 . The CI Acid

Blue 40 was tested individually. The preliminary absorbance

values given in Table A-1 have corresponding concentration

calculation equations given in Figure A-1 of the Appendices.

The formulas can be used to calculate the concentration y of

any one of the dyes individually or in a mixture given the

absorbance x value. The formulas were not used in subsequent

129

calculations because (0,O) was used as the first point in the

linear regression which may have had a large effect on the

calibration curve. More accurate formulas were calculated for

the various dyes and dye mixtures used during the

experimentation which did not use (0,O) as a data point.

Additionally, absorbance values were recorded for

distilled water samples treated at the principal iron addition

levels , These values were used to assess the color

contribution of the iron in each sample. However, iron color

contribution was not linear as expected, Table 3-15 shows the

maximum iron color contribution at 354 mg/l iron addition

after which color contribution decreases. Also, several sets

of distilled water were treated throughout the experimentation

for the purpose of iron color subtraction, Different iron

treatment levels were used between sets to match treatment

levels used in sample testing. Figure 3-1 shows three sets

of distilled water samples treated at various iron levels and

absorbance values at 610 nm. Much fluctuation was observed

in absorbance values from set to set although color did

increase in each set with increases in iron addition to about

350 mg/l iron after which color contribution dropped o f f .

This phenomena is not understood, but it is possible that some

equilibrium is offset forcing more iron out of solution at

iron levels in excess of 350 mg/l or perhaps that flocculation

is maximized at that point decreasing the iron in solution and

therefore the color. Incidently, the ferric iron is a rust

130

Table 3-15 Absorbance values for distilled water treated with the Andco Process. The absorbance values represent the color contribution of the iron.

..

Absorbance

5 0 7 5 9 1

Iron Level 1 5 0 ( m g / l ) 3 0 0

3 5 4 450

4 1 0 n.m 510 nm

0.0094 0.0042 0.0212 0.0096 0.0297 0,0144 0.0113 0.0053 0.0476 0,0268 0.0533 0,0392 0.0428 0.0261

610 m

0.0033 0.0085 0.0075 0.0027 0.0193 0.0337 0.0188

131

0.12

0 100 200 300 4 0 0 500

IronLevel (mg)

F i g u r e 3-1 A b s o r b a n c e v s . I r o n L e v e l ( m q / l ) a t 610 nm f o r t h r e e d i f f e r e n t s e t s of t r e a t e d d i s t i l l e d wa te r b l a n k s u s e d t o m e a s u r e i r o n c o l o r c o n t r i b u t i o n .

132

color, but a mixture of ferric and ferrous is nearly black;

the proportion of each present in solution would likely have

an effect on the absorbance. This factor may be significant

as the ferrous iron is continually oxidizing to ferric iron,

changing their respective proportions in solution until all

of the ferrous iron is oxidized, which may take several days

or longer. The amount of iron in solution may also depend on

what other species are present. A dye in water may cause more

iron to precipitate or flocculate than with distilled water

alone, where the iron may stay in solution, Because the

behavior of the iron color at low iron addition levels was

mostly linear but at higher iron levels was non-linear, it was

not decided whether or not iron color subtraction would be a

valid practice. For this reason, two sets of absorbance and

percent removal values are given, one set with iron color

contribution (from Table 3-15) subtracted off and one with the

original data. Except with very pale samples, iron color

contribution could probably be considered negligible.

Betore and after iron color subtraction absorbance values

are given in Table A-2 in the Appendices for the 15 mg/l and

25 mg/l acid dye mixture (AR361, A0156, A B 2 7 7 ) . -The stock

solution absorbance value& were used to develop the

corresponding concentration calculation equations shown in

Figure A - 2 . ' These equations were used to calculate remaining

total dye concentration at each treatment level, the resulting

percent removal values are shown in Table 3-16. Percent

134 - *

reduction ranged from a few percent up to roughly 99%.

Increasing iron addition appeared to consistently increase

color removal until removal was achieved around 95% after

which further iron addition showed little improvement.

Maximum removal seemed to occur from 150 to 350 mg/l iron

addition. A second run of the acid dye mixture was made with

25 mg/l and 50 mg/l stock solutions; however, iron color was

not subtracted out as shown in Table 3-17. Once again,

maximum removal occurred around 250-350 mg/l iron addition

although with noticeably less removal than the first acid dye

mixture results had shown. Unlike COD treatment, higher

initial dye concentrations appeared to have better removal

than lower concentration samples. The Acid Blue 4 0 was tested

..

for absorbance values at 5, 10 and 20 mg/l sample

concentrations to develop a concentration calculation equation

as shown in Table A-3 in the Appendices. The absorbances were

taken only at 610 nm as it is the principal absorbance

wavelength for blue, and because the Acid Blue 4 0 was to be

tested individually. Excellent color removal was observed for - Acid Blue 40 at 250-350 m g / l iror? addition in the range of

roughly 80-97% as shown in Table 3-18. Iron colo2 was also

subtracted out revealing even higher color reduction (in the

event that iron color subtraction is valid). Another dye was

tested at 25 mg/l and 50 mg/l stock solution concentrations,

Procion Blue MX-2G. Absorbance values were recorded at 610

nm and removal percents provided as shown in Table 3-19. The

135

Table 3-16 Acid dye mixture percent reduction values f o r 15.(mg/l) and 25 (mg/l) samples with increasing iron addition ~ A ) before iron color absorbance subtraction B) after iron color absorbance subtraction. * Represents percent increase in absorbance.

Percent Reduction

A) 410 mu 510 nm

15 (mg/l) 7 5 45.9 44.0 150 58.9 48.6 300 * +29.3 18.0 450 27.0 53.3

Iron Level ( m g / l )

25 (mg/l) 9 1 4.1. 0 150 76.2 354 68.7 450 78.3

B)

15 (mg/l) 7 5 150 300 450

I r o n Level ( m g / l )

9 1 150 354 450

- 55.5 66.9 76.2 79.0

Percent Reduction

4 1 0 mu 510 nm

61.8 67.4 6.3

59.0

52.5 50.6 42.1 76.4

54.3 81.0 92.6 97.5

63.2 69.7 96.9 92.9

610 nm

* +19.0 29.7

* +15.5 25.9

26.5 68.4 55.6 65.3

610 nm

* + 1.0 35.4 25.5

** 66.2

36.0 71.8 98.8 89.3

136

Table 3-17

25 (mg/l) 50 150 250 350

Iron Level "/I)

50 (mg/l) 50 150 250 350

Corresponding color reduction percent for the acid dye mixture at 25 (mg/l) and 50 (mg/l) sample concentrations with increasing iron addition.

Percent Reduction

4 1 0 nm 510 nm

21.0 69.3 68.0 77.6

+1.0 56.8 66.2 74.0

29.4 72.0 65.6 76.5

+2.5 58.9 68.3 70.2

610

17.6 44.3 63.6 75.4

+15.0 + 8.8 44.4 42.9

137

Table 3-18 Absorbance and percent color reduction values for A . B . 40 25 (mg/l) sample A) before iron color absorbance subtraction B) after iron color absorbance subtraction.

A) 610 nm % Reduction

2 5 ( m g / l ) stock ( 0 ) 0.4044 50 0 3510

Iron Level 150 0.3302 "/l) 250 0.0960

350 0 . 0 3 0 2

- 13.0 18.3 77.6 94.2

B) 610 nm % Reduction

2 5 . ( m g / l ) stock ( 0 ) 0.4044 50 0 . 3456

Iron Level 150 0.3198 "1) 250 0.0810

350 0.0192

14.6 21.1 81.4 97.0

138

Table 3-19

Iron Level "/l)

Absorbance with percent reduction values for Procion Blue MX-2G at 25 (mg/l) and 50 (mg/l) sample concentrations.

2 5 (ms/l)

3

Stock (0) 0.1255 - 610 nm Reduction

50 0.1132 9.8 100 0,0700 44.2 150 0.0800 36.3 250 0.0536 57.3 350 0.0550 56.3 450 0.0555 55.8

50 (ms/l)

31 610 nm Reduction

0.2121 - 0.0531 75.0 0.0531 73.5 0.0580 72.7 0,0483 77.3 0.0455 78.5 0.0574 72-9

139

percent color reduction was good but not exceptional with

maximum values around 7 8 % .

Treated Dvebath Water Reuse Results

The treated dyebath water reuse tests involved the use

of both nylon heatset carpet yarn and scoured cotton fabric.

Only one set of dyeings was done with the cotton fabric, using

a Procion direct cotton dye. All other sets of dyeings used

acid dyes and the nylon carpet yarn. The carpet yarn dyeings

were done using two types of dyebath constitutions. The first

type, referred to as Wnspiked,Ir were prepared in the same

conventional manner as the control sample except that treated

water (a dye solution simulating an exhausted dyebath, treated

electrochemically to remove color such that the water can be

reused in dyeing) was used in place of the tapwater required

in the dyebath. The second type, referred to as llspiked,lt had

additional auxiliary chemicals and stainblocker chemicals

added directly to the dyebaths to simulate residual chemical

content remaining in the dyebath water after treatment.

Details on the constitution of both types of dyebaths are

given in the experimental section (Chapter 11).

Also, in the dyeings referred to as A.B. 277 dyeing #1,

A . R . 361 dyeing #1 (for unspiked samples) and the A . B . 2 7 7 /

A . R . 361 purple mixture, residual dye content in the treated

water was accounted for by reconstituting the dyebaths;

however, this did not seem to improve or effect the color

140

matching results and so was not taken into account in

subsequent dyeings. Also, the iron treatment level used

appeared to have no noticeable effect on the dyeing behavior

of the samples as::long as color removal was better than 60%.

The results of the dyebath reuse tests appeared to

indicate at best, the possibility of dyebath reuse after

treatment. Tables 3-20 through 3-24 show color matching data

for several sets of dyeings. Values are given for the control

standard and samples dyed with water treated at various levels

of iron addition (the number at the top of each column

represents the iron addition level in mg/l used to treat the

water used in that particular dyeing). A spiked sample is

denoted when the letters 88ST88 appear after the iron addition

level, and a dyeing carried out in the same manner twice is

denoted by the iron level followed by an I8Att and then a I1BI8.

The color matching values f o r each sample are L* = lightness-

darkness, a* = redness-greenness, b* = yellowness-blueness,

C* = saturation, and h = hue. The I8Dl8 values represent the

differences -in the above variables between the control

standard sample and the treated water sample, with DE being

the total color difference. Table 3-20 summariees color

matching values for the first;set of dyeings for Acid Blue 277

and the Acid Blue 277/Acid Red 361 purple dyeing. The values

of the first A.B. 277 dyeing can be compared to the values

given in Table 3-21 for the second set of A.B. 277 dyeings.

Table 3-22 gives color matching values for the first A.R. 361

141

T a b l e 3-20 CIE LAB color matching for A.B. 2 7 7 - d y e i n g 81 and A.B. 277/A.R. 361 purple dyeing #1.

A.B. 277 Dveinq

S t a n d a r d - 197 - 283

L* 41.37 40.57 37 . 70 a* -2.57 -2.87 -1.16 b* -44.45 -43 . 50 -44.37 C* 44.52 43 . 59 44 . 38 h* 266.69 266.23 268.50

DL* --- -0.79 -3 . 67 D a * --- -0.30 1 . 4 1 Db* --- 0.95 0.08 DC* --- -0.93 -0.14 DH* --- -0.36 1.40 DE* --- 1.27 3.93

Pumle Dveinq

Standard 207A

L* 31.62 34 .71 a* 28.11 26.87 b* -21 .41 -21.95 c* 35.34 34 . 69 h* 322.70 320.76

DL* --- 3.09 D a * --- -1.24 Db* --- -0.53 DC* --- -0.64 DH* --- -1.18 DE* --- 3.37

- 207B

33.32 27.30

-22.50 35.37

320.51

1.70 -0.81 -1.08 -0.04 -1.35

2.17

32.15 26.80

-23.35 35.54

318.94

0.53 -1.31 -1.93

0 . 2 1 -2.33 -2.39

142

Table 3-21 CIE LAB color matching values for-A.B. 277 ST = stainblocker/auxiliary spiked dyeing #2 .

sample.

Standard - 1 2 1

L* 4 2 . 1 9 42 .37 a* -3.19 -3.28 b* -43.70 -43 .95 C* 43 .82 4 4 . 0 8 h 265 .82 265 .74

DL* --- 0 . 1 8 'Da* --- -0 .19

Db* --- -0 .25 DC* --- 0 . 2 6 DH* --- -0 .07 DE* --- 0 .32

1 2 1ST

4 3 . 6 1 4 .22

-42 .86 4 3 . 0 7

2 6 4 . 3 7

1 . 4 3 -1.03

0 .84 -0 .75 -1.10

1 . 9 5

- 207

40 .55 -2.08

-44 .81 44 .86

267 .34

-1.64 1.11

-1.11 1.04 1.17 2 .27

207ST 287

4 4 . 9 8 42 .34 -4 .70 -3.10

-42 .71 4 4 ; 0 7 42 .97 44 .18

2 6 3 . 7 1 265 .98

2 .79 0.16 -1.51 0.09

0 . 9 9 -0.36 -0.85 0 .36 -1.60 0.12

3.33 0 . 4 1

287ST

4 3 . 9 5 -4.20

-43 .30 4 3 . 5 0

2 6 4 . 4 5

1 . 7 6 -1.01

0 . 4 0 0 .32

-1.04 2 .07

143

Table 3-22

Standard

L* 45.54 a* 54.20 b* -1.77 C* 54.23 h 358.13

CIE LAB color matching values f o r A.R.361 dyeing

121

46.71 53.86 -2.20 53.90 357 . 66

1.17 -0.34 -0.42 -0.32 -0.44 2.07

#1. ST =stainblocker spiked sample

121st

43.89 54.09 -0.52 54.09 359.45

-1.65 -0.11 1.24

-0.13 1.24 1.29

- 207

42.99 54.51 0.05

54.51 0.06

-2.54 0.32 1.82

-0.29 -1.83 3.14

207ST

46.64 53.70 -1.61 53.72

358.29

1.10 -0.50 0.16

-0.51 0.15 1.22

- 287

46.12 53.57 -1.76 53.60 358.12

-0.58 -0.62 0.01

-0.62 -0.01 0.85

2875t

45.06 54.29 -0.99 54.30

358.96

-0.48 0.09 0.78 0.07 0.78 0.92

144

dyeing including

matching values

including spiked

somewhat higher

first .

spiked samples. Table 3-23 gives color

for the second set of A.R. 361 dyeings

samples . Overall color difference was

n the second A.R. 361 dyeing than in the

The Procion Red dyed set was the only set done on scoured

cotton, all other sets used nylon 6 , 6 270°F Superba heatset

yarn. Visual observation of the samples showed that samples

had poor leveling. This was no doubt due to the small scale

beaker dyeing process in which the sample was folded or

crumpled into a ball in the dyebath. Stirring did not seem

to help dye diffusion very much. Color differences as given

in Table 3-24 were very large, although the 121 sample had a

smaller'color difference as compared to the other samples.

For the most part, samples within a given set of unspiked

samples came closest to the tapwater dyed control sample.

Spiked samples did not come nearly as close, and in most cases

were quite far from a match with the control sample. In fact,

of the ten spiked samples only one had a DE value less than

1.00 (A good color match has a DE value less than or equal to

1.00). However, within a given set of spiked samples, the

dyeing similarities were much,closer when comparing one spiked

sample to another within the same set. In fact, of all the

spiked samples, the DE values ranged from approximately 0.30

to 1.70 with an average value of about 1 corresponding to

color matches within the sets of spiked samples. One of the

145

Table 3-23 CIE LAB color matching values f o r AR 361 dyeing #2. ST = stainblocker spiked sample.

Standard 121 - 207 - 287

L* 40.43 40.82 42.05 41.56 a* 56.06 55.84 55.93 55.59 b* 2.96 2.28 1.60 1.85 C* 56.14 55.89 55.96 55.62 h 3.03 2.34 1.64 0.74

L* a* b* C* h

DL* Da* Db DC DH DE

Standard

40.43 56.06 2.96 56.14 3.03

0.39 1.62 1.13 -0.22 -0.13 -0.48 -0.68 -1.36 -1.11 -0.25 -0.19 0.52 -0.67 -1.36 -1.09 0.82 2.12 1.66

121ST

42.47 56.19 1.75

56.21 1.79

2.04 0.12

-1.21 Q.07 -1.22 2.37

207STA 207STB 2875t

43.54 55.93 0.73

55 . 94 0.74

3.11 -0 . 13 -2.24 -0.20 -2 . 23 3.84

44 . 15 56.14 0.41

56.14 0.42

3.72 0.08

-2 . 55 0.00

-2.55 ' 4.51

43.90 55.88 0.34

55.88 0.35 '

3.47 -0.18 2.62 0.26

-2. 62 4.35

146

Table 3-24

L* a* b* C* h DL* Da* Db* DC* DH* DE*

CIE LAB color matching values f o r Procion Red dyeing #l.

Standard

62.64 45.85 -4.14 46.03 354.85 ---

62.18 46.73 -4.81 46.98 354.12 -0.06 0.89 0.68 0.95

-0.59 1.12

64.25 42.80 -5.15 43.11 354.12 2.01

-3.04 -1.02 -2.92 -1.33 3.79

60.59 47.60 -5.12 47.88

353.87 -1.65 1.76

-0.98 1.84

-0.80 2.60

147

major causes of color difference between the spiked samples

and the control was probably due primarily to the stainblocker

chemical addition, as opposed to the excess auxiliary

chemicals, as the ',ispiked samples generally appeared lighter

than the unspiked samples. Of a total of ten spiked dyeings

eight were lighter and two darker than the control sample.

It was observed during the experiments that a noticeably

larger amount of dye washed off the spiked samples during the .

tapwater rinse. This would seem realistic since the

stainblocker chemical present in the spiked dyebaths very

probably competed with the dye for dye sites, reducing the

amount of dye uptake onto the fiber.

A color match may possibly be achieved by compensating

f o r the effects of the stainblocker chemical by increasing the

dye concentration in the bath. Also, the presence of a

stainblocker chemical in the dyebath may reduce the amount of

fresh stainblocker chemical needed in the finishing process.

On the other hand, the presence of stainblocker chemicals in

the dyebath may also inhibit or alter the usual uptake of

fresh stainblocker chemicals. In any case, the fact that

initial dyeings showed consistency within each set .(even if

there were no color matches) suggests that optimization of the

dyebath with chemical compensation might be all that is

necessary tox reduce color differences. If the exhausted

dyebath water is segregated from the wastewater containing the

stainblocker, the optimization of the recycled dyebath water

148

would likely be much easier. Also, the color differences

occurring in the samples may be partially due to the small

beaker dyeings which were used. Chemical concentration

differences are much more likely in the small volume beaker

dyeings than in full-scale dyeings. A one drop difference in

dye solution addition is significant in beaker dyeings and can

cause measurable color differences between samples, However,

the purpose of these experiments was not to achieve exact

color matches, but rather to observe the general behavior of

the treated dyebath water in reuse tests, and to determine if

full-scale dyeing tests would be worthwhile to attempt,

A Studv of the Color Removal Process

The purpose of this section was to determine if dyes were

removed, totally by adsorption onto the ferrous hydroxide or

by dye alteration or some combination of the two. The scope

of this research was not necessarily to determine what

degradation products were present so much as to determine if

there were degradation products. However, where ever

possible, details on’possible destruction/altered products are

given. It is also possible that if there are degradation

products that the concern for safety may be negligible as the

degradation products may further degrade at such a fast rate

as to make over concern unjustifiable. Camp [16] found that

anilines degraded by photolysis and oxidation within a few

days after preparation and weeks old samples had no measurable

149

traces of aniline or its oxidation products. Camp [16] also

indicated that sulfonated

water soluble keeping them

molecules of the hody thus

type degradation products.

An attempt was made to

degradation products were quite

from bioaccumulating in the fatty

reducing the threat of sulfanilic

calculate the actual concentration

of the remaining chemical content at each wavelength studied.

Standard solutions of known concentratiorl were measured for

absorbance values at each wavelength for each chemical tested,

and linear regression was used to develop calibration

equations. However, the use of these equations was found to

be invalid as they were only useful for calculating the

residual concentration of pure starting material (i.e. Food

'Blue #2 ) at the selected wavelengths, Unfortunately, after

electrochemical treatment the solution consisted of not a pure

starting material, but rather, a mixture of starting material

and degradation products. Because the absorptivity values

were calculated for the pure starting material, they were not

applicable to the mixture, as each degradation product would

have its own absorptivity value at each wavelength. For this

reason results are given as percent change in absorbance

relative to the absorbance o:f the starting material before

treatment (i.e. the control sample) at the selected

wavelengths and arrows indicate whether there was an increase

or decrease in absorbance. Also, the absorbance spectra for

the control, standard and treated samples of each set are

150

given in Appendix B, Figures B-1 through B-26.

Results For Acid Blue 277

The Acid Blue 277 control sample was a 20 mg/l

concentration solution treated with 121, 207, and 287 mg/l

iron addition levels. The A.B. 277 was the first sample

tested in this series of experiments, and was used to observe

the behavior of a major carpet dye with electrochemical

treatment. The structure of A.B. 277 is proprietary but is

believed to be an anthraquinone type dye. The anthraquinone

structure is not nearly as susceptible to reduction as azo

bonded structures due to the stabilized conjugated bonds in

the multiple ring system of the dye. It should show

significantly less indication of alteration and/or

destruction. The results in Table 3-25 show the percent

change in absorbance for selected wavelengths for each treated

sample and standard stock solution measured with the

spectrophotometer. The higher wavelengths, 556 and 604 nm

represent the visible region in which blue dye has its

absorption maxima. The A.B. 277 turned out to be a weak

absorber even in the blue region; however, its absorption in

this region was strong enough to show color removal with

electrochemical treatment. T.pe spectra of the 3.0 mg/l and

10.0 mg/l standards were very useful in determining what

approximate reductions at each wavelength could be expected.

The 3.0 mg/l standard was very consistent having absorption

reductions of approximately 88 to 92 % on the average (

Table 3-25 Percent change in absorbance for ACID BLUE 277 standards and treated samples at 8 deet e d wavelengths.

Wavelengths (nm)

Stimdnrds 220 254 284 332 386 556 604

3" 5. 86.7% J. 89.7% 4 91,3% 5. 97:9% 3. 91.5% L 88.2% 3. 89.1%

10mg/L J. 49.0% .L 59.9% 5. 62.0% 4 62.7% .1.47.1% $ 54.6% 5. 58.9% . --

Iron Levels ------ 121mg/L 5. 30.0% 3. 57.3% 4 50.0% 0.00% I' 3.53% L 44.0% 3. 82.1%

207mg/L 4 52.0% 4 55.5% 4 82.6% 3.1 74.2% 4 58.8% 4 92.0% \1. 94.9%

287mg/L .L 28.5% 5. 55.5% 4 46.1% 3. 6.45% .& 459% J, 60.0% 5. 66.6% '*

152

relative to the spectral absorptions measured for the A . B . 277

control solution of 20 mg/l ) . However, with an increase in

concentration to 10.0 mg/l the percent decrease in absorption

was fairly consistent values for 254, 332, 556 and 604 nm but

was roughly 10 - 12% less at 220 and 386 nm. Since this was a standard solution these observations had to be taken into

account when observing the corresponding treated samples'

spectra. In order to suggest dye alteration with some amount

of confidence, the differences between the color removal

absorption reductions and the aromatic region absorption

reductions would need to be greater than 10 to 12 % to account

forthe variabilitywithinthe standards. The treated samples

showed significantly more variability in absorption decreases

allowing for conclusions to be drawn. The 121 mg/l treatment

level shows nearly the same color removal as the 3.0 mg/l

standard but 25% less reduction at 254 nm, the maximum

absorption wavelength for benzene and 30 % less at 284 nm, the

substituted benzene region. The absorption is 50 % less at

220 nm, but the 10 to 12 % difference observed for the

standard must be taken into account. This gives an actual

difference of about 40 %. The 207 and 287 mg/l samples did

not exhibit as great a variability in absorption reduction

from wavelength to wavelength. For instance, the color

removal was 94.9% at 604 nm for the 207 mg/l treated sample

and 88.5% at 254 nm indicating a closely corresponding

aromatic content reduction. The 207 and 287 mg/l treated

153

samples had noticeably less absorbance reduction at 386 nm

ranging from 2 0 to 35%. The 386 nm is at the lower end of the

visible wavelengths corresponding to absorbance of the color

yellow. After studying the different absorbance reductions,

it was decided that adsorption/complexing was probably

predominating, but that the areas of remaining aromatic

content at high color removal levels indicated color

substituents alteration as opposed to dye molecule

destruction. It is not unlikely that the carbonyl group(s)

could have been reduced to alcohol groups causing the removal

of color without aromatic content removal (or anthraquinone

structure destruction). If the anthraquinone had been broken

into aromatic fragments a much lower or even an increase in

absorbance reduction would have been observed in the aromatic

absorption region (molecule destruction would have resulted

in a molar increase in benzene type derivatives).

Resuzts For FD&C Food Yellow #5

The Food Yellow #5 dye control sample was a 30 mg/l

concentration solution treated at 151, 237, and 337 mg/l iron

addition levels. The Food Yellow #5 was tested because of its

purity and because it had an azo bond incorporated. into its

structure. The results in Table 3-26 indicated that actual

dye destruction of some type was occurring. Again, the 3.0

and 10.0 mg/l standards were used to observe the variability

in absorbance reduction from wavelength to wavelength. The

3.0 mg/l sample was fairly consistent in percent absorbance

154

Table 3-26 Percent change in absorbance for FDBrC Food Yellow #5 standards and treated samples at selected wavelengths.

Wavelengths (nm)

standards 220 229 254 266 433

Iron ]Levels

151 q / L 4 31.3%

237 mg/L J. 39.4%

337 mg/L J. 43.8%

\t 72.3%

f 29.4%

?' 17.6%

r 9.8 yo

& 62.5% & 73.3%

4 17.7?? 4 62.3%

5. 13.6% $ 64.9%

4 23.6% 4 67.4%

.. .

4 90.0?/0

J. 68.4%

& 88.6%

6 88.9%

.L 90.00!

155

reduction, but the 10.0 mg/l standard

not exceeding 20 %. For this reason a

greater than 20 % would be needed to

showed some fluctuation

variation in absorbance

support the possibility

of dye destruction. Fortunately, there was a large difference

between color removal for each of the treated samples (89 to

90 % decrease at 433 nm yellow absorption wavelength) and the

corresponding aromatic region removal (31to 44 % decrease at

220 nm, 10 to 30 % increase at 229 nm, 14 to 24 % decrease at

254 nm and 62 to 67 % decrease at 266 nm). These values are

significantly different from the color removal values such

that they support actual dye destruction. Characteristic

absorption wavelengths for the possible degradation products

obtained from the Sadtler Handbook [33] also support the

conclusions. One likely degradation product of Food Yellow

#5 would be sulfanilic acid which has absorption maxima at 253

nm and 266 nm where 14-24% and 25-30% less reduction in

absorbance is observed respectively comparedtothat for color

removal. Also, aniline would be a likely product and it has

absorption maxima in the r-egion of 230 nm and 254 nm where an

increase in absorption is observed from 10 to 30 % and a

decrease of only 14 to 24% respectively . Also,-.residual

amines and carbonyl groups absorb strongly at 195 nm to 220

nm; the values at 220 nm would be at the beginning of this

region and they show a decrease of only 31 to 44%. Visual

observation of the treated samples showed that their color was

significantly different fromthat of dilute standard solutions

156

of Food Yellow #5. The treated samples were pale beige/tan

as compared to pale yellow for the diluted standards

(incidentally, dilute aniline appears beige/tan in color) . The data support':-that dye destruction is occurring in this

case with likely reduction of the azo bond predominating.

Results For FD&C Food Blue #2

The Food Blue #2 control sample was a 28 mg/l

concentration solution treated with 1 5 4 , 237 and 337 mg/l iron

addition levels. The Food Blue #2 was selected out of

curiosity to observe the behavior of a dye with a carbon-

carbon double bond as compared to the behavior of the azo-

bond. The results in Table 3-27 indicate dye destruction as

with the Food Yellow #5. The 3.0 and 10.0 mg/l standard

samples were very consistent in percent absorbance reduction

with no more than a 12% difference between any two

wavelengths. The treated samples were also fairly consistent

in percent absorbance reductions from wavelength to

wavelength. Color removal is given at 612 nm ranging from 78

to 90%. A 5% to 11 % less reduction in absorbance is observed

at 286 nm, another characteristic absorbance region for

aniline. At 2 5 4 nm a 59 % to 69 % reduction in absorbance

occurs corresponding to benzene, benzene sulfonic acid, and

sulfanilic acid-sodium salt (i.e. 254, 253, 252.5 nm

respectively) , all of which are possible degradation products of 'Food Blue #2. Absorption decreases at 232 nm were very low

at 3 to 28 %. Aniline has an absorption maxima at 233 nm.

157

Table3-27 Percent change in absorbance for FD&C Food Blue ff2 Seandards'and treated samples at selected wavelengths.

Wavelengths (nm)

L O e / L J, 69.6% .L 65.7% J. 61.1% .L 58.8% & 57.5%

Iron Levels

237efL & 46.0?! 28.3% .L 68.6% 5-- 81.6% 86-8om

337mg/L J. 39.0?! 5- 16.7% 4 58.6% & 70.8% J. 78.1%

158

Absorption was also found to increase at 220 nm going off-

scale in most cases by 210 nm and continuing strong to 195 nm.

As discussed earlier, amine, aldehyde, ketone and nitro groups

absorb strongly Pn this region. The data indicate the ..

production of aniline and sulfanilic acid products which would

only be possible if the carbon-carbon double bond was reduced

during the treatment process.

Results For Azobenzene

The azobenzene control sample was a 34 m g / l concentration

solution treated with 154, 302 and 345 mg/l iron treatment

levels. The azobenzene was treated in a 3.5% methanol/

distilled water solution to achieve sufficient solubility.

More supportive data could be collected by running a high

purity solution of azobenzene through the electrochemical

treatment unit for the simple reason that it has a limited

number of possible degradation products, Azobenzene in

solution is a bright yellow color which lends itself to this

type of study by allowing color removal to be compared with

aromatic content removal, Color removal, if not by

adsorption, would be caused by destruction bf the azo bond

which is the main chemical substituent responsible'for color

of the azobenzene. The results in Table 3-28 indicate azo

bond destruction, also Table 3-29 shows percent change in

absorbance r for the azobenzene degraded with sodium

hydrosulfite and absorbance values for dilute aniline. The

3.0 and 10.0 m g / l standards were very consistent in percent

Table 3-28 Percent change h .absorbance for Azobenzene standards and treated samples at selectcd wavelengths.

Wavelengths (nm)

3mg/L

IOmg/L

Iron Levcts

151mg/L

302mg/L

-------

345mg/L

J. 83.8%

5. 52.4%

'l' 85.0%

'? 197,%

'l' 69.3%

4 84.1%

-& 53.6%

'I' 150.%

'I' 149.%

1' 145,%

.I 87.6%

$. 5,8.9%

T 190.%

?' 259.%

'T' 219,%

$ 84.1%

5. 53.0%

1' 4,20%

'P 22.6%

J. 9.80%

3. 82.4% 8&5%

5. 50.6% '4 60.6%

J. 59.3% 4' 1.57%

3. 53.0% It\ 200.?40

3. 65.4% + 85.0% I

160

Table 3-29 Percent change in absorbance for Azobenzene 34 mg/L degraded w i t h sodium hydrosulfite at selected wavelengths and absorbances for dilute Aniline.

Azobenzene degraded with sodium hydrosulfite

Wavelengths (nm)

220 230 254. 285 3 s 4L9

T42.9% 1'51.1% T124Yo 452.0% +84.8% 498.2%

Anfline (unknown wnceniration - dilute)

0.67 1.18 0.14 0.20 0.00 0.00

. .

I

f

reduction of absorbance, varying no more than 10 % betwc

two wavelengths. The strongest absorption maxima f

azobenzene control sample was at 319 nm (compared with

for the Stadtler. value 1331). The percent reduct

absorbance at this wavelength (319nm) for the treated

was 53 % to 65 %.

(the same as the treated sample) reduced with

i

< The identical concentration of azo

c

rl

c

hydrosulfite, had a corresponding 85% absorbance reduc

319 nm. On the other hand, at 285 nm the 150 and 3

iron treated samples increased 4 to 23 % in abs

respectively while the 345 mg/l treated sample decrea:

10%. It also happens that aniline has an absorptior

at 286 nm being a likely cause of the absorbance inc

In addition, absorbance increased dramatically from 22

nm for all treated samples; this was also the case

azobenzene degraded with sodium hydrosulfite. The ot

absorption maxima for aniline is 233 nm which might co

to the 150% increase at 230 nm for the treated samp

addition, benzene absorbs strongly at 254 nm; where

a 190 to 250 % increase in absorption for the treated

One other supporting observation was made. The spe'c

dilute aniline was observed to be nearly superimpose;

the spectra of the treated samples and that of th

hydrosulfite reduced azobenzene. One unexplained

observed only with the treated samples was an inc

absorption at 419 nm ranging from 2 to 200 %. This

1 6 2

the aromatic absorption region and in the visible region.

This indicates a possible change in the chemical molecule

separate from destruction. This might be caused by incomplete

reduction of the..azo bond to form hydrazobenzene which may

have some color contributing characteristics. This may also

be supported by the fact that the color of the treated samples

was beige/tan as opposed to pale yellow for dilute azobenzene

and clear/transparent for the sodium hydrosulfite degraded

sample. The chemically degraded azobenzene was probably more

completely reduced as indicated by the clear transparent

color. Regardless of the actual destruction mechanism or

degree of destruction, the data do support that azo bonded

species are highly susceptible to some form of alteration

and/or destruction during the electrochemical treatment

process employed in these experiments.

Cost Analysis

Electrochemical treatment appears to have good potential

as an textile wastewater treatment system. A cost analysis

was performed to compare the Andco Treatment System's daily

annual operating costs and capital investment costs with other

wastewater treatment systems. Figure 3-30 [ 3 8 ] shows a cost

break-down that includes consumables (chemicals, iron etc.),

and power requirements. The power requirements for iron

generation, as well as, the iron used are the largest

contributors to the operating cost for the Andco Process.

The daily and annual operating costs are given for each of the

Iron Addition Level mg/l

Consumables' 150 200 250 300 350 450 550 650 $/day

1,119.315 Annual opr. cost 269.800 354,645. 439.845 524,690 609,535 78 1 ,OOO 949,270

p s p e 3-30 Annuatand W y operating costs for a mill treating 1.0 million gallons per day for Werent b n treatment levels, Iron sludge production is also given. Values rounded to the nearest whole number and annual values represent 355 days.

a Lui. 135 S1.162 9J470-17,OOo tons 2500 tans

165

standard iron addition levels most commonly used. The values

given are representative for a plant treating one million

gallons per day. Annual operating costs range from $ 270,000

for a plant using. 150 mg/l iron addition to $ 1,120,000 for

a plant using 650 mg/l iron addition. For a plant treating

dyebath water, the lower iron treatment levels would be

sufficient, thus costing less than a plant treating a high COD

wastestream containing auxiliaries and stainblockers, which

would require higher iron addition levels greater than 300mg/l

Figure 3-31 [1],[38] gives A) The capital cost, B) The annual

operating cost, C) The daily operating cost and D) The annual

sludge production in tons, for several selected water

treatment systems including the Andco Treatment Process. Each

has been calculated for plants treating one million gallons

per day. At iron treatment levels of 300 mg/l, the Andco

Process is comparable in capital investment cost to chemical

coagulation/precipitation, powdered activated carbon. with

extended activated aerobic sludge, and granular activated

carbon (without regeneration) . Although the capital costs are similar, the annual operating costs for the Andco Process are

up to twenty-five times less than chemical precipitation and

activated carbon. However, both chemical precipitation and

activated carbon have several times greater sludge production.

On the other hand, at iron treatment levels greater than

300mg/l the Andco Process is comparable in operating cost to

ozonation. Ozonation, which has considerably less annual

166

operating cost and no sludge production, would seem like the

better option, as it is very effective at destroying

wastewater constituents. Ozonation also has no sludge

disposal cost, although . I the ozone must be generated at the

treatment site, requiring its own generation equipment.

Although, the initial capital investment for ozonation is

roughly 2 to 2 1/2 times greater than for the Andco Process,

the cost differential can be recovered within about two years.

Even at lower iron addition levels, the Andco Process is still

more expensive to operate than ozone. Other than ozone, all

of the intermediate and advanced treatment systems listed are

considerably more expensive to operate than the Andco Process.

Although activated carbon and membrane systems may be the most

effective systems for actual chemical removal, in some cases

actual removal is not necessary and only adds to the expense

of wastewater treatment. For this reason, processes like

ozonation and the Andco Electrochemical Treatment Process

which destroy (and/or remove and destroy in the case of the

Andco Process) a chemical's structure may be sufficient. The

final selection of a wastewater treatment system is determined

by an individual plant's water treatment needs and available

investment and operating capital.

167

CHAPTER IV

CONCLUSIONS AND RECOMMENDATIONS

Chemical Oxysen Demand Reduction

The Andco Electrochemical Treatment Process appears to

be a potential prospect for use in textile industry wastewater

treatment. Through the first portion of this study it war

found that the Andco Process effectively removed chemical

oxygen demand levels by 25% to 95% depending on the chemical,

its concentration and the iron treatment level. The newer

stainblocker formulations achieved removal levels' averaging

80%. Industry should be applauded for the quick response time

in reformulating their stainblockers to reduce threat to the

environment and meet effluent standards. Chemical oxygen

demand values were not very conclusive as far as dyes were

concerned, as their COD values approached the background error

for the COD test. Polymer addition used in the flocculation

process was found-to contribute negligible amounts of COD to

the treated samples. However, the polymer COD in the

distilled water blanks was not easily determined. as the

results were often masked in Bhe background error for the COD

test. A better method of assessing the polymer COD would have

been to prepare more concentrated solutions of polymer and

168

determine the COD with increasing concentration. In this

manner, the COD of the dilute polymer added to flocculate a

sample could be calculated from a calibration equation

developed from the COD values determined for the higher

concentration polymer solutions. The COD contributed to the

sample could then be estimated to be no more than the COD for

the corresponding volume of dilute polymer used to flocculate

the sample. One other possible contributer to the COD of the

treated samples was the ferrous hydroxide from the

electrochemical treatment. The amount of COD contribution

would be proportional to the amount of ferrous hydroxide

present in the sample, which would depend on how fast it

oxidizes to ferric hydroxide before the COD test is performed

on the sample. A more accurate experiment would have employed

the use of treated samples bubbled with oxygen to oxidize the

ferrous iron to ferric iron before running the COD test. The

contribution to COD would probably be very small as a large

portion of ferrous iron oxidizes to ferric iron during the

electrochemical treatment, due to air exposure and constant

solr-ltior. mixingi

Also , auxiliary chemicals were reduced by about 40 %

to 70 &. Chemicals like Guar Gum were difficult to floc at

concentrations higher than 0.3 g/1 because the chemical

floated to ‘the surface away from the iron. The anionic

surfactant tested had good removal as long as the concentation

of the stock solution was less than 0.8 g/1 after which

169

flocculation became difficult due to excessive foaming of the

surfactant. The total carbon tests appeared to work best for

testing higher COD samples like stainblockers as opposed to

dyes. The TC tksts confirmed increased organic (carbon)

reduction with polymer flocculation, as opposed to settling

alone without polymer addition. The COD and TC results for the

dyes were too inconsistent and variable to draw any

conclusions on dye removal, The absorption testingturned out

to be a much better method for studying color removal.

Color Removal

The color removal study showed very high removal levels

approaching 100% in some cases, Average color removal values

ranged from 75% to 95%. Mid-range concentrations around 25

mg/l of dyes were removed the best, while concentrations that

were lower (i,e. 15 mg/l) or higher (i.e. 50 mg/l) generally

had lesser removal values. Also, iron levels from 150 mg/l

to 2 5 0 mg/l had the best removal values. Higher iron addition

did not appear to significantly increase removal percents.

In addition, iron color contribution was studied and was found

to fluctuate from one treated set to another. Iron color

contribution within a given test set was found to. increase

until an iron level of 300-3.50 mg/l was reached after which

the color level dropped off. The cause of this phenomena was

not known but thought to be a consequence of several factors.

One possibility was that at higher iron levels the iron

flocculated better removing more iron , thus reducing iron

170

color contribution. Another possiblity was that the

proportion of ferrous (greenish yellow in color) to ferric

(reddish color) iron changed significantly (for unknown

reasons) at higher ‘iron addition levels, thus causing a change

in color contribution. At higher iron levels the sample would

have been exposed to air and mixing longer allowing for more

oxidation of the ferrous iron. Dye samples reaching high

levels of removal at high treatment levels appeared to take

on the characteristic color increase and drop-offs associated

with iron blanks. The iron may also behave differently when

a chemical species (i.e. dye) is present as opposed to when

it is in a distilied water soultion, Due to the unusual

behavior of the iron color, its subtraction from dye samples

for iron color contribution may not be valid. The color

contribution of the iron was very small in relation to

absorbance values of treated samples except at very high

treatment levels and so could be considered to be negligible,

Treated Dvebath Water Reuse

The results of the dyebath water reuse study indicated

that electrochemically treated dyebath water might be

acceptable for reuse with further optimization.,’*Further

experiments using full-scale’dyeings would be necessary to

optimize the dyebath for use with treated water. Full-scale

testing wou‘ld greatly reduce the concentration errors

associated with the small beaker dyeings and give more

conclusive results as to how close a color match could be

1 7 1

obtained between control and treated samples. Also, a

treatment system set up for treated dyebath water reuse should

be positioned in the process such that it receives segregated

water coming directly from the dyebath with no further

finishing chemical content (i.e. stainblockers). A mixed

wastestream would increase the difficulty in adjusting the

recycled dyebath. Also, a company investing in such a

treatment system with water reuse capabilities would be

foolish not to use the system to its fullest potential.

Although the recent year has seen precipitation levels above

average, the trend until recently has been drought. By merely

adjusting some of the plumbing within the plant water reuse

capability would at least be available during times of water

limitations, minimizing impact on production during droughts,

even if the system was not utilized in such a capacity on a

permanent basis.

Mechanism of Dye Removal

Results of the mechanism of dye removal study showed that

dyes containing azo bonds are highly susceptible to

alteration/destruction. Depending on the exact structure of

the dye, various degradation products were indicated in the

results including: 1) aniline, 2) sulfanilic acid, 3 ) benzene

sulfonic acid, 4 ) benzene, and 5) hydrazobenzene. Also, it

appeared that dyes with carbon-carbon double bonds were also

highly susceptible to destruction at the double bond. The

anthraquinone dye that was tested appeared to be primarily

172

removed by some precipitation process, possibly adsorption or

complexin2. The anthraquinone was less susceptible to

destruction in the electrochemical treatment process most

likely due to the, stabilized anthraquinone ring structure.

To determine the exact degradation products and their

various content proportions, a further study should be

performed using a more sophisticated analytical method. One

possibility would be to use high performance liquid

chromatography (HPLC) to separate the degradation products

present in the treated water samples. Having some idea of the

identities of the degradation products from the present study,

standards of the suspected degradation products could be

prepared and run through the HPLC to determine retention times

and characteristic peak heights. This information could then

be compared with HPLC chromatograms for the mixture of

degradation products to see if there are any identical

retention times and peak heights. The HPLC could also be

combined with mass spectrophotometry (Mass Spec) which can

give the exact structure of a chemical by matching the

unknown's spectrum with a computer library of spectra,

eliminating all but a few possibilities for chemical

identification. In addition, HPLC could also be combined with

electrochemical detection as used by Camp [16] in her research

work on azo dye/degradation product identification. The HPLC

would be used to separate the mixture of degradation products

in the treated water samples. The electrochemical detection

173

would measure the reduction potential of the separated

degradation products using a mercury dropping electrode.

Although dyes may have more than one reduction potential, (due

to the existence in some cases of more than one electroactive

site where reduction occurs), usually the reduction potential

is an identification characteristic for each dye and

degradation product.

Some modification of the treatment process may be

necessary if certain known toxins are identified in the

treated wastewater. Strategically combining the

electrochemical treatment process with another complimentary

process may eliminate the threat of degradation products. As

mentioned earlier, the Andco Process could be followed by

. oxidative aerobic sludge L digestion to further degrade any

degradation products produced in the Andco Electrochemical

Treatment Process. Other more expensive options could follow

this treatment system producing approximately the' same

results. Ozonation or carbon adsorption would work well in

this capacity, but aeEobic sludge or an oxidation pond would

no doubt be the less expensive route. Also, as suggested by

Camp [16] , the dye degradation products of azo bonded dyes appear to degrade rapidly by air oxidation and photolysis.

This may make over concern unjustifiable, as they may not

exist in the environment long enough to be a threat. However,

due to the serious nature of a possible health or

environmental threat being created, further work needs to be

174

done to determine the lifetimes of the different degradation

products in the environment. Should a further study on

degradation product identification be done, a corresponding

study on the biodegradation of the degradation products (that

is, any products that should be identified) should also be

done. The biodegradation study would identify those products

which do not readily degrade in the environment.

Additionally, toxicity (and/or carcinogenity and mutagenity)

of the degradation products that do not readily degrade may

have to be determined if they are not already known, so that

assessment of the threat of such degradation products to

health and the environment may be complete,

Cost Analysis

..

The results of the costs analysis show that the Andco

Process is comparable to ozonation in terms of its treatment

capabilities. However, ozonation has considerably less

operating costs even though the initial investment may ‘be

higher.

less operating costs than the advanced treatment systems

studied. The final decision in selecting a water treatment

system depends on the degree of treatment required’and the

available investment and opedating capital. The Andco

Process would work well as a pretreatment process most likely

preceding oxidative aerobic sludge. The electrochemical

treatment would effectively remove color and reduce COD, while

the aerobic sludge would most likely further degrade any

The Andco Process still has up to twenty-five times

175

degradation products produced by the Andco Process. If future

studies show that the degradation products produced are not

a threat to health or the environment, the aerobic sludge

treatment may not.be necessary.

The Andco Electrochemical Treatment Process appears to

have definite applications in textile wastewater treatment.

Other electrochemical treatment systems as described earlier

in the introduction, may also work well treating textile

wastewater. One drawback of the electrochemical treatment

processes in general is the production of large amounts of

iron sludge, which contains various pollutants collected

during the treatment process. The iron sludge itself may need

to be studied for its leaching characteristics with textile

wastewater contaminants. Depending on these characteristics,

the iron sludge may or may not be disposable in a municipal

landfill.

176

APPENDICES

177

Appendix b

Absorbance Values and Calibration Equations f o r the Color Removal Study

178

Table A-1 Absorbance values for the prominent carpet mill dyes used in the dye removal tests.

A.B. 277 5.0 10.0 20.0

A.R. 361 5.0 10.0 20.0

A.O. 156 5.0 10.0 20.0

A.B. 40 5.0 10.0 20.0

ABSORBANCE

410 nm 510 610 nm

0.0090 0.0084 0,0457 0.0203 0.0204 0 . 0912 0,0422 0.0448 0.1802

0.0140 0,0492 -0.0018 0.0301 0.1201 0 , 0019 0.0620 0.2284 0.0026

0.0056 0,0445 -0,0006 0.2194 0.0826 0.0005 0,4175 0.1750 0.0019

0.0250 0.0235 0.0872 0.0471 0.0400 0,1673 0.0752 0.0695 0.3270

A.B. 277

179

410 nm 510 nm 610 nm

A.R. 361

410 nm 510 nm 610 nm

A.O. 156

410 nm 510 n m 610 nm

y = 0.883 + 452.461 x y , = 1.565 + 411.758 x y = -0.134 + 111.639 X

y = 0.609 + 312.638 X y = 0.475 + 84.420 X y = 9.211 + 2728.086 x

y = -0.302 + 48.359 x y = 0.218 + 113.640 x y = 8.036 + 6050.950 x

A . B . 4 0

410 nm y = -3.129 + 301.338 X 510 nm y = -2.%57 + 327.605 x 610 nm y = -0.459 + 62.561 x

Figure A-1 Dye concentration calculation equations developed from absorbance and concentration values in Table 3-15 by linear regression. x = absorbance, y = concentration ((mg/l))

180

Table A-2 Acid dye mixture absorbance ( m g / l ) and 25 ( m g / l ) samples color absorbance subtraction. color absorbance subtraction. ..

15 ( m g / l ) stock 75 150 300 450

Iron Level “/I)

25 ( m g / l ) stock 91

150 354 450

15 ( m g / l ) stock 75 150 300 450

Iron Level “/I 1

25 ( m g / l ) stock 91

150 354 450

Absorbance

values for 15 A) before iron B) after iron

4 1 0 nm 510 nm 610 rm

0,1315 0,1096 0.0474 0.0716 0.0623 0.0563 0 , 0542 0,0571 0.0332 0.1722 0,0913 0.0545 0.0969 0.0518 0.0348

0.2230 0.1889 0.0785 0,1308 0,0828 0.0578 0.0530 0.0613 0.0244 0.0692 0.0439 0.0349 0,0477 0.0385 - 0.0273

Absorbance

4 1 0 nll~ 510 nm 610 rm 0,1315 0.1096 ‘ 0.0474 0.0504 0.0527 0.0478 0.0429 0.0548 0.0305 0.1246 0.0645 0.0352 0 , 0541 0.0257 0.0160

0.2230 0.1889 0.0785 0.1011 0.0684 0.0503

0.0159 0.0047 0.0012 0.0049 0.0124 0.0085

0.0417 0.0560 0.0222

181

Acid D y e Mixture

410 nm y = 6.9 x + 112.24 x 510 nm y = 0.137 + 132.60 x 610 nm y = - 2 . 5 x + 318.30 x

Figure A-2 Acid dye mixture concentration calculation equations developed from absorbance and concentration values in Table A. x = absorbance y = concentration ((mg/l))

182

Table A-3 Concentration and absorbance values fo r A c i d Blue 40 and corresponding dye concentration c a l c u l a t i o n equation.

0 5 10 20

Absorbance 610 nm

0 0.0872 0.1673 0.3270

y = -3.3 x + ( 4 . 4 1 9 ) X

183

Appendix B

Absorption Spectra f o r the Mechanism of Dye Removal Study

i I - i

184

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185

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186

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187

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the effectiveness of the andco electrochemical treatment ... · the effectiveness of the andco...

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