A COMPARATIVE STUDY OF SEWERAGETREATMENT PLANTS WITH DIFFERENT

TECHNOLOGIES IN THE VICINITY OF CHANDIGARHCITY

A DISSERTATION

SUBMITTED TO THE PANJAB UNIVERSITY, CHANDIGARH IN THE

PARTIAL FULFILLMENT OF THE REQUIREMENT FOR

THE AWARD OF THE DEGREE OF

MASTER OF ENGINEERING

IN

ENVIRONMENTAL ENGINEERING

SUBMITTED BY

PRERNA SHARMA

POST GRADUATE ENVIRONMENTAL ENGINEERING DEPARTMENT

PEC UNIVERSITY OF TECHNOLOGY

CHANDIGARH – 160012

2013

I

CERTIFICATE

This is to certify that the thesis entitled “A comparative study of seweragetreatment plants with different technologies in the vicinity of Chandigarh”which is being submitted herewith by Prerna Sharma (Roll no. 11201009) in partialfulfillment for the award of the degree of Master of Engineering (EnvironmentalEngg.) of PEC University of Technology Chandigarh is an authentic record of thestudent’s own work carried out under our supervision and guidance. The matterpresented in the thesis has reached the standards fulfilling the requirements of theregulation for the award of said degree.

Dr. R.K Khitoliya Dr. Shakti Kumar

Professor and Head Associate Professor

Deptt. Of Civil Engineering Deptt. Of Civil Engineering

PEC University of Technology PEC University of Technology

Chandigarh Chandigarh

II

ACKNOWLEDGEMENT

The present shape of this study has come forth only after contribution from differentspheres. Had this encouragement and support not been forth coming, it would havebeen extremely difficult to complete the thesis work in time.

I acknowledge my sincere thanks to my main guide Dr. R.K. Khitoliya, Professorand Head, Deptt. Of Civil Engineering, PEC, Chandigarh for his continuous supportin my thesis work. Mere words can never encompass the profound gratitude. I feelfor his guidance, valuable critism and constant inspiration that never let me waverduring the course of my thesis.

I am also highly thankful to my Co-Guide Dr. Shakti Kumar, Associate Professor,Civil Engineering department, Chandigarh without whose timely help andsuggestions my thesis work would never have been possible. I express my sincerethanks to him for providing me the necessary guidance throughout my thesis work.

I would like to thank Mr. Harish Kumar Saini, S.D.O, Sewerage Treatment Plant,Diggian, Mohali and Sewerage Treatment Plant Raipur Kalan for providing accessto these plants and for providing me the information i needed.

I own my special thanks to Mr. Pandey, Scientist, Chandigarh Pollution ControlCommittee for providing relevant information regarding my thesis work.

I am very thankful to Mr. Baljeet Singh, Mr. Bhardwaj and Mr. K. S. P Rana forproviding a pleasant atmosphere and necessary facilities in the laboratory.

Last but not the least, i am deeply grateful to my beloved parents for their moralsupport, love and encouragement without which it would not have been possible toreach this stage of my life.

Prerna Sharma

III

III

LIST OF TABLES

TABLE NO. CONTENTS PAGE NO.

1.1Comparison between Raipur Kalan,Raipur Khurd and Mohali STP 10

3.1 Parameters and Methods for their Analysis 34

3.2

Central Pollution Control Board (CPCB)

General Standards for the discharge of

Environmental Pollutants according to The

Environment (Protection) Rules, 1986

Schedule-VI Part–A : Effluents

49

4.1Characteristics of Influent and Effluent ofall the 3 STP’S in the month of FEB 54

4.2Characteristics of Influent and Effluent of

all the 3 STP’S in the month ofMARCH

55

4.3Characteristics of Influent and Effluent ofall the 3 STP’S in the month ofAPRIL

56

IV

4.4Average Characteristics of Influent andEffluent of all the 3 STP’S 57

4.5Comparison of all the three STP’s Effluentwith CPCB Effluent Discharge Standardsinto Inland Surface Water

63

4.6Overall Performance orRemoval/Reduction Efficiency of all the3 STP’s

66

4.7

Comparison of Mohali STP, (MBBR)

Technology, Average Effluent With the

CPCB Effluent Discharge Standards into

Land for Irrigation

72

V

LIST OF FIGURES

FIGURE NO. CONTENTS PAGE NO.

1.1Typical Stages in the Conventional

Treatment of Sewage2

1.2General diagram showing variousparts of an Sewerage Treatment

Plant3

1.3 Tube Chip Shaped Bio-Carriers 5

1.4Flow diagram showing MBBRtechnology at STP “Diggian”,

Mohali6

1.5Flow diagram showing UASB

technology at STP Raipur Kalan8

1.6Flow diagram showing ASP

technology at STP Raipur Khurd9

3.1 pH apparatus 35

3.2 Digital Thermometer 36

3.3 Soxhlet Apparatus 38

3.4 Glass Fibre Apparatus for TSS 40

3.5 BOD Incubator 42

3.6 Spectrophotometer 45

3.7Spectrophotometer Showing

Standard Curve46

4.1Graphical Representation of pH of

all the 3 STP’s 58

VI

4.2Graphical Representation of

Temperature of all the 3 STP’s 58

4.3Graphical Representation of TSS of

all the 3 STP’s 59

4.4Graphical Representation of TDS

of all the 3 STP’s 59

4.5Graphical Representation of Oil

and Grease of all the 3 STP’s 60

4.6Graphical Representation of BOD

of all the 3 STP’s 60

4.7Graphical Representation of COD

of all the 3 STP’s 61

4.8Graphical Representation of Cl- of

all the 3 STP’s 61

4.9Graphical Representation NO3-N of

all the 3 STP’s 62

4.10Graphical Representation of NH3 -

N of all the 3 STP’s 62

4.11Graphical Representation of of

PO4- OF all the 3 STP’s 63

4.12Graphical representation ofParameter exceeding CPCB

Standard65

4.13

Graphical representation of TSS forOverall Performance or

Removal/Reduction Efficiency of3 all the STP’s

67

4.14

Graphical representation of TDSfor Overall Performance or

Removal/Reduction Efficiency of3 all the STP’s

68

VII

4.15

Graphical representation of CODfor Overall Performance or

Removal/Reduction Efficiency of3 all the STP’s

69

4.16

Graphical representation of BODfor Overall Performance or

Removal/Reduction Efficiency of3 all the STP’s

70

4.17

Graphical representation of BODfor Overall Performance or

Removal/Reduction Efficiency of3 all the STP’s

71

VIII

LIST OF ABBREVIATIONS

BOD Biochemical Oxygen Demand

COD Chemical Oxygen Demand

FIG Figure

CPCB Central Pollution Control Board

mg/L Milligram Per Litre

TDS Total Dissolved Solids

TSS Total Suspended Solids

NO3 -N Nitrate Nitrogen

NH3 –N Ammonia Nitrogen

Cl- Chloride

PO4- Phosphate

Temp Temperature

MPN Most Probable Number

STP Sewerage Treatment Plant

ASP Activated Sludge Process

UASB Upflow Anaerobic Sludge Blanket

MBBR Moving Bed Biofilm Reactor

C Degree Celsius

IX

ABSTRACT

Chandigarh city has a well planned underground network of pipes for the disposal of sewerage

generated in the city. The sewerage system of the city has been designed by taking into account the

natural slope of the city, which is from north to south. Chandigarh city hosts three Sewerage Treatment

Plants (STP’s) namely: STP “Diggian” located at sector 66 of S.A.S Nagar, Punjab Territory,

Mohali, based upon MBBR (Moving Bed Biofilm Reactor) technology which is at a distance of

about 4km from the nearest planned sector 47, STP Raipur Kalan located at a distance of 6km

from Chandigarh adjoining to railway station based upon UASB (Upflow Anaerobic Sludge

Blanket) technology and STP Raipur Khurd, based upon ASP (Activated Sludge Process)

technology located on Chandigarh-Ambala highway at a distance of approximately 8 km from

Interstate Bus Terminal sector 17, 1 km from Airport and 3 km from Railway Station. These

plants are designed and constructed with an aim to manage waste water so as to minimize or remove

organic matter, solids and other pollutants before it enters a water body.

In the present study various Physico-Chemical and Biological Parameters are evaluated and are

compared with the Central Pollution Control Board (CPCB) General Standards for the

Discharge of Environmental Pollutants Part–A : Effluents, into Inland Surface Water according

to The Environment (Protection) Rules, 1986 Schedule-VI because the Effluent from these

STP’s enters river Ghaggar. Also the performance of each STP was evaluated in terms of

Removal/Reduction Efficiency.

Since out of 30 MGD of STP, Mohali 10 MGD treated waste water is reused for Irrigation

purpose in various gardens and lawns of Sector : 19, 20, 21, 29, 30, 33, 34, 36, 40, 42, 43, 44, 46,

47, 48, 51 and 52 of Chandigarh city therefore Average Effluent of this STP is compared with

the CPCB Effluent Discharge Standards into Land for Irrigation.

It was observed according to the results obtained that BOD value of the Effluent of STP Raipur Kalan

and Raipur Khurd was not under permissible limit during the duration of study and Average Phosphate

value of Raipur Khurd was exactly upto permissible limit according to Central Pollution Control Board

X

(CPCB) General Standards for the Discharge of Environmental Pollutants Part –A: Effluents, into

Inland Surface Water according to The Environment (Protection) Rules, 1986 Schedule-VI.

According to the results obtained it was also revealed that all the Physico-Chemical and Biological

Parameters evaluated for STP Mohali was under permissible limit according to CPCB Effluent

Discharge Standards into Land for Irrigation and also into Inland Surface water.

Also it was revealed from the performance study that efficiency of the three STP’s mentioned above

was poor with respect to removal of TDS (Total Dissolved Solids) in contrast to the removal

/reduction efficiency in other parameters like TSS (Total Suspended Solids), BOD (Biochemical

Oxygen Demand) and COD (Chemical Oxygen Demand).

The order of removal/reduction efficiency was 1.TDS(39%) 2.COD(56%) 3.TSS(76%)

4.BOD(79%), 1.TDS(46%) 2.TSS(51%) 3.BOD(73%) 4.COD(78%) and 1.TDS(55%) 2.COD(75%)

3.TSS(78%) 4.BOD(88%) respectively in Raipur Kalan STP, Raipur Khurd STP and “Diggian”

Mohali STP. In comparison with each other, out of the three STP’s, “Diggian” STP Located at

Mohali showed better results for the effluent, its reduction efficiency for BOD is 88% and is

highest among Raipur Kalan STP and Raipur Khurd STP which is 79% and 73% respectively.

From the evaluation it is further revealed that Mohali STP based upon MBBR technology have more

stable results than Raipur Kalan STP, based upon UASB technology and Raipur Khurd STP, based

upon ASP technology. The order of overall performance for the technologies studied in different

STP’s are: 1.MBBR 2.UASB 3.ASP which proves that MBBR technology is ahead to UASB and ASP

technology in the treatment of sewage.

Additionally, the working principle, problems associated with the operation and maintenance of all the

three STP’s is also discussed.

CONTENTS

CERTIFICATE I

ACKNOWLEDGEMENT II

LIST OF TABLES III

LIST OF FIGURES V

LIST OF ABBREVIATIONS VIII

ABSTRACT IX

CHAPTER 1

INTRODUCTION

1.1 General 1

1.2 30 MGD Sewerage Treatment plant, “DIGGIAN” 4based upon MBBR technology, at sector66 S.A.S Nagar, Phase 11, Mohali

1.3 5 MGD sewerage treatment plant based upon 7UASB technology at Raipur Kalan, Chandigarh

1.4 1.25 MGD Sewerage Treatment Plant based upon 9ASP technology at Raipur Khurd, Chandigarh

1.5 Objectives of the study 11

1.6 Significance of the study 11

CHAPTER 2

REVIEW OF LITERATURE

2.1 The innovative Moving Bed Biofilm Reactor/ solids contact 12

reaeration process for secondary treatment of municipal wastewater

2.2 Biological Fixed Film Systems 12

2.3 The Moving Bed Bio film Reactor 13

2.4 Treatment of pesticide wastewater by Moving-Bed Biofilm 13

Reactor combined with Fenton-coagulation pretreatment

2.5 Performance comparison of a pilot-scale UASB and DHS system 14

and activated sludge process for the treatment of municipal wastewater

2.6 Efficiency evaluation of sewage treatment plant with different 14

technologies in Delhi (India)

2.7 Treatment of domestic wastewater in an Up-Flow Anaerobic Sludge 15

Blanket reactor followed by Moving Bed Biofilm Reactor

2.8 Assessment of the efficiency of Sewerage Treatment Plants 16

2.9 Performance Evaluation of Moving Bed Bio-Film Reactor Technology 16

for Treatment of Domestic Waste Water in Industrial Area at MEPZ

(Madras Exports Processing Zone), Tambaram, Chennai, India

2.10 Biofilms in Water and Wastewater treatment 16

2.11 A review: The anaerobic treatment of sewage in UASB and EGSB 17

Reactors

2.12 Comparison of overall performance between "Moving-Bed" 18

and "Conventional" Sequencing Batch Reactor

2.13 Anaerobic sewage treatment in a one-stage UASB reactor and a 18

Combined UASB-Digester system

2.14 Performance evaluation of a UASB – activated sludge system 19

treating municipal wastewater

2.15 Combined Anaerobic/Aerobic Secondary Municipal Wastewater 20

Treatment: Pilot-Plant Demonstration of the UASB/Aerobic Solid

Contact System

2.16 Improvements in Biofilm Processes for Wastewater Treatment 21

2.17 Fluidized Bed Biofilm Reactor for wastewater treatment 22

2.18 Integrated application of Upflow Anaerobic Sludge Blanket 23

Reactor for the treatment of wastewaters

2.19 Potential of a Combination of UASB and DHS Reactor as a 23

Novel Sewage Treatment System for Developing Countries:

Long-Term Evaluation

2.20 A review of the upflow anaerobic sludge blanket reactor 24

2.21 Removal of Slowly Biodegradable COD in Combined Thermophilic 25

UASB and MBBR Systems

2.22 Technical review on the UASB process 26

2.23 Wastewater Treatment in Baghdad City Using Moving Bed 27

Biofilm Reactor (MBBR) Technology

2.24 The performance enhancements of Upflow Anaerobic Sludge 28

Blanket (UASB) reactors for domestic sludge treatment – A State of the

art review

2.25 Treatment of raw domestic sewage in an UASB reactor 28

2.26 Upgrading Activated Sludge Systems and reduction in excess sludge 29

2.27 Developments in wastewater treatment methods 29

2.28 Microbial attachment and growth in Fixed-Film Reactors: Process 30

startup considerations

2.29 Small wastewater treatment plants: A challenge to wastewater engineers 31

2.30 Sustainable options of post treatment of UASB effluent treating 31

sewage: A review

CHAPTER 3

MATERIALS AND METHODOLOGY

3.1 Selection of Sites and Sampling Points 33

3.2 Collection of Samples 33

3.3 Parameters Analyzed 33

3.4 Methods for Analysis 35

CHAPTER 4

RESULTS AND DISCUSSIONS

4.1 Results 54

4.2 Discussions 73

CHAPTER 5

CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions 84

5.2 Recommendations 85

5.3 Future Scope of Work 86

REFERENCES 88

1

CHAPTER 1

INTRODUCTION

1.1 General

In early days waste products of the society including human excreta were been collected, carried &

disposed of manually by the human beings and this system is called dry conservancy system. This

system leads to bad smell and health hazard. Now a day with the march of civilization &

development proper disposal of waste done by a new system called sewerage system that had

replaced the old dry conservancy system. In the sewerage system, the waste mixed with water is

called sewage. Sewage carried through close pipes or lines called sewers to the place away from

the residential area under the force of gravity to Sewerage Treatment Plant (STP). Here sewage

treated before disposing in environment. Sewage includes dissolved and suspended organic solids,

number of living microorganism, which lead into bad condition, odour and appearance.

Microorganism may contain disease-producing (pathogenic) bacteria and viruses that can be

readily transferred by sewage from sick individuals to well ones. So by removing it properly

environment can be maintained in an acceptable and safe condition.

State and Local authorities with statutory authority in pollution control have established standards

of purity that are necessary to prevent pollution of natural waters. When waste is discharged into

controlled amount, the standards set by State and Local authorities are maintained. Domestic

sewage consists of waste from toilets, lavatories, urinals, bathtubs, showers, home laundries and

kitchens. It also includes similar wastes from medical dispensaries and hospitals.

Treatment Methods Generally Followed at an STP

Sewerage Treatment Plant is a facility designed to receive the waste from domestic, commercial

and industrial sources and to remove materials that damage water quality and compromise public

health and safety when discharged into water receiving systems.

It works on the objective to allow human, domestic and industrial effluents to be disposed of

without danger to human health or unacceptable damage to the natural environment.

Conventional wastewater treatment consists of a combination of physical, chemical, and biological

processes and operations to remove solids, organic matter and nutrients from wastewater.

2

Fig 1.1: Typical stages in the Conventional Treatment of Sewage

3

Fig 1.2: General diagram showing various parts of a Sewerage Treatment Plant

3

Fig 1.2: General diagram showing various parts of a Sewerage Treatment Plant

3

Fig 1.2: General diagram showing various parts of a Sewerage Treatment Plant

4

1.2 30 MGD Sewerage Treatment Plant, “DIGGIAN” based upon MBBR

Technology, at Sector 66 S.A.S Nagar, Phase 11, Mohali

This Sewerage Treatment Plant, spread over an area of 48 acres, is located at Sector 66 of S.A.S.

Nagar in Punjab Territory which is at a distance of about 4 km from the nearest planned Sector 47.

The present capacity of the Sewerage Treatment Plant is 30 MGD. The sewage received at this

STP is subjected to primary, secondary and tertiary treatment. 30 MGD is treated upto tertiary

level and out of 30 MGD, 10 MGD treated waste water or sewage is recycled back to the city for

irrigation of open spaces/ gardens. The 20 MGD treated sewage is disposed off in an open Nallah

and finally it meets river Ghaggar.

The main components of STP “DIGGIAN”, Mohali Primary Treatment

Components (MBBR Technology)

1. Raw Sewage Sump : 4

2. Inlet Channel

3. Settling Chamber

4. Mechanical Screens : 4

5. Grid Separators : 4

Secondary Treatment Components

1. Fluidized Aerobic Bioreactor Media

2. MBBR units (Moving Bed Bio Film Reactors) : 2 (MBBR-I and MBBR- II)

3. Claritube settlers: 2

Tertiary Treatment Components

1. Disinfection (Chlorine contact), Chlorine Contact Tank : 1

2. Filtration: Dual filter Media, one coconut shell filter media & other coarse fine aggregates

as the other media.

5

Fig. 1.3: Tube Chip Shaped Bio-Carriers used in MBBR technology

The above Fig shows tube chip shaped bio-carriers .The bio-carriers were made of organic

polymer (high density polyethylene) that was mixed with nano sized inorganic ingredients (cokes

powder, zeolite and so on); the nano-sized inorganic ingredients were purposely mixed to enlarge

the surface area and roughness of the carrier for microorganism better accommodation.

6

Fig 1.4: Flow diagram showing MBBR technology at STP Mohali

7

1.3 5 MGD Sewerage Treatment Plant based upon UASB Technology

Raipur Kalan, Chandigarh

STP Raipur Kalan is located at a distance of 6km from Chandigarh adjoining to railway station and

is based upon UASB (Upflow Anaerobic Sludge Blanket) technology.

The main components of STP Raipur Kalan (UASB Technology)

1. Inlet channel

2. Inlet chamber

3. Mechanical screens : 2

4. Manual Screen : 1

5. Grit Channel : 2

6. Parshal Flume : 2

7. Collection Chamber : 1

8. Divison Box : 1

9. Distribution Box : 4

10. UASB Reactor : 2

11. Final Polishing Unit

12. Sludge Drying Beds

8

Fig 1.5: Flow diagram showing UASB technology at STP Raipur Kalan

IINLET CHANNEL

INLET CHAMBER

SCREENS

GRIT CHANNEL

PARSHAL FLUME

COLLECTION CHAMBER

DIVISON BOX

DISTRIBUTION BOX

UASB REACTORS

EFFLUENT CHANNEL

FINAL POLISHING UNIT

SLUDGEWITHDRAWALPIT

SLUDGE DRYINGBEDS

9

1.4 1.25 MGD Sewerage Treatment Plant base upon ASP Technology at

Raipur Khurd, Chandigarh

STP Raipur Khurd, based upon ASP (Activated Sludge Process) technology is located on

Chandigarh-Ambala highway at a distance of approximately 8 km from Interstate Bus Terminal

sector 17, 1 km from Airport and 3 km from Railway Station, Chandigarh.

The main components of STP Raipur Khurd (ASP Technology)

1. Raw sewage Sump : 4

2. Inlet Channel :1

3. Mechanical Screens : 2

4. Grit Channel : 1

5. Aeration Tanks : 6

6. Secondary Sedimentation Tank: 1

7. Sludge Drying Beds

Fig 1.6: Flow diagram showing ASP technology at STP Raipur Khurd

IINLET CHANNEL

MECHANICAL SCREENS

GRIT CHANNEL

AERATION TANKS

SECONDARY SEDIMENTATION TANK

FINAL EFFLUENT

SLUDGE DRYINGBEDS

10

Table 1.1: Comparison between Raipur Kalan, Raipur Khurd and Mohali STP

S.NO PARAMETERSRAIPUR KALAN STP

(UASB TECHNOLOGY)

RAIPUR KHURD STP

(ASP TECHNOLOGY)

MOHALI STP

(FAB/MBBR

TECHNOLOGY)

1. Type of process Anaerobic Aerobic Aerobic, Attached growth

2. Expandability Very Limited Very Limited

High. Higher loads can be

accepted

with extra media

Filling.

3.Area required for

STP, in hectares3.825 2.925 0.5575

4.Total land cost,

Rs. Lacs45.9 35.1 6.69

5.

Total power

cost/annum, Rs.

Lacs1.77 47.56 36.5

6.

Maintenance cost

per annum, Rs.

Lacs

(Including

manpower, power,

chemicals)

72.47 156.03 47.71

7.Capital Cost, Rs.

Lacs600 922.5 585

8. Source of sewage

Manimajra township,

Modern Housing

Complex,Shivalik Enclave

and Mauli Jagran Colony

Raipur Khurd,

Hallomajra, Behlana,

Makhnanmajra and

Daria village

Sector 20,21,43,44,47,48,

36,50,51,52,49,61,62,64,8

0,81,83 of Chandigarh

city

11

1.5 Objectives of the Study

1. To analyze the physico-chemical parameters of influent and effluent of all the three STP’s

studied.

2. To study the biological parameters of influent and effluent of all the three STP’s.

3. To determine the Nutrient Load in each of the STP studied.

4. To determine the intensity and variation of pollution level in each of the STP studied.

5. To know practically about the working principle of all the three STP’s studied.

6. To determine the overall performance of each STP in terms of removal/reduction efficiency.

1.6 Significance of the Study

Proper treatment should be given to sewage in Sewerage Treatment Plant before their disposal into

inland surface water or for reuse of sewage effluent for irrigation purposes.

My study on the above three STP’s is done to check whether the effluent from the three STP’s

studied complies with the Central Pollution Control Board (CPCB) General Standards for the

discharge of environmental pollutants Part –A: Effluents, into Inland Surface Water according to

The Environment (Protection) Rules,1986 Schedule-VI , because the effluent from these STP’s

meet the river Ghaggar i.e the source of Inland Surface Water.

Also this study will help us to know that among ASP, MBBR and UASB which technology is

better for the treatment of sewage and producing effluent of good quality.

12

CHAPTER 2

REVIEW OF LITERATURE

2.1 Fluidized Bed Biofilm Reactor for wastewater treatment

Wen K. Shieh and John D. Keenan (1986) found that the fluidized bed biofilm reactor (FBBR)

represents a recent innovation in biofilm processes. Immobilization of microorganisms on the

small, fluidized particles of the medium results in a high reactor biomass holdup which enables the

process to be operated at significantly higher liquid throughputs with the practical absence of

biomass wash-out.

The process intensification (i.e., a reduction in process size while maintaining performance)

achieved in FBBRs makes this innovative technology particularly attractive in biological

wastewater treatment, commercial biomass conversion, and ethanol and biochemical production

applications. In this chapter, the present understanding of biofilm phenomena involved in the

operation of FBBRs is reviewed. Special emphasis is placed on the microbial and kinetic aspects of

FBBRs and practical design considerations and current applications are described.

2.2 Treatment of raw domestic sewage in an UASB reactor

R.A. Barbosa and G.L. Sant'Anna Jr (1989) carried out a study in which the treatment of raw

domestic sewage at ambient temperatures in an upflow anaerobic sludge blanket (UASB) reactor

with a volume of 120 l. and a height of 1.92 m was studied. The sewage had an average BOD5 of

357 mg l−1 and COD of 627 mg l−1. Approximately 75% of the organic materials were in the

suspended fraction.

The sewage temperature ranged from 18 to 28°C during the experimental period. The reactor

operated continuously for 9 months and assessed self-inoculation and raw domestic sewage

purification. The unit was started without inoculum and ran during the entire experimental period

with a hydraulic retention time of 4 h. During the experiment, a sludge bed build-up was observed.

At the end of the experimental period, the predominance of spherical granular particles up to 6–8

13

mm in diameter was evident. After a 4-month operation, it was observed that the

inoculation/acclimatization steps had been concluded. Removal efficiencies of BOD5 = 78%, COD

= 74% and TSS = 72% were obtained. A typical gas production factor of 80 l kg−1 COD added was

observed and the CH4 content of the biogas was 69%.

2.3 Technical review on the UASB process

Kwan‐Chow Lin et al. (1991) studied about a comprehensive review of the UASB wastewater

treatment process. Factors affecting granulation of the anaerobic sludge, start‐up of the process and

operation of UASB reactor are analyzed. Criteria about design and construction of the UASB

reactor are described, and studies on mathematical modeling of fluid flow pattern, sludge

distribution and biological conversion of substrate in the UASB reactor are reviewed. Finally,

applications of the process to the treatment of various types of wastewater are summarized.

2.4 Microbial attachment and growth in Fixed-Film Reactors: Process

startup considerations

A.P. Annachhatre and S.M.R. Bhamidimarri (1992) studied that Optimal steady-state performance

of any biofilm reactor requires a fully developed and mature biofilm. During fixed-film reactor

startup phase, biofilm is in process of development and accordingly, process performance is

difficult to quantify. Environmental, cellular and surface factors greatly influence the process of

biofilm formation during reactor startup.

Improved knowledge of nutritional, toxicological and environmental requirements of wastewater

degrading microorganisms has helped define optimal microbial growth conditions. In case of

anaerobic fixed film reactors the startup is hindered by low microbial growth rates, strict

environmental requirements and limited ability of methanogens to adhere and form fixed biofilms.

These obstacles could be overcome by proper support media selection and formulation of

appropriate inoculation procedures and startup strategies.

14

2.5 Small wastewater treatment plants — A challenge to wastewater

engineers

Markus Boller (1997) found that three conferences on “Small Wastewater Treatment Plants”

organized by the IAWQ Specialist Group demonstrate worldwide interest and activities in this

matter and the need to exchange experience concerning planning, design, construction, operation,

maintenance and control of small treatment plants. In near future, the number of small treatment

works will increase tremendously and will be accompanied by a strong demand for information on

appropriate procedures and technologies.

Pollution problems caused by small wastewater flows are usually restricted to small areas,

however, in view of the high per capita costs, treatment requirements and alternatives have to be

studied carefully. In comparison to larger plants, more pronounced and different boundary

conditions such as load fluctuations, operation and maintenance problems, per capita costs, and a

large variety of feasible treatment and disposal systems ask for experienced engineers with a broad

and sound knowledge in rural water quality management. The technical alternatives reaching from

mechanical and simple biological low rate systems such as ponds, sand filters and reed beds to

complex high rate suspended and fixed biomass reactors have to be evaluated regarding plant size,

operation safety, reliability, demand for skilled personnel, investment and operation costs.

In this respect, water engineers are increasingly challenged, not only to deal with a broad range of

present and future treatment technologies, but also to integrate economical and social aspects into

their evaluations.

2.6 A review: The anaerobic treatment of sewage in UASB and EGSB

Reactors

Lucas Seghezzo et al. (1998) conducted the study and observed that anaerobic treatment process is

increasingly recognized as the core method of an advanced technology for environmental

protection and resource preservation and it represents, combined with other proper methods, a

sustainable and appropriate wastewater treatment system for developing countries.

15

Anaerobic treatment of sewage is increasingly attracting the attention of sanitary engineers and

decision makers. It is being used successfully in tropical countries, and there are some encouraging

results from subtropical and temperate regions.

In this review paper, the main characteristics of anaerobic sewage treatment are summarized, with

special emphasis on the upflow anaerobic sludge blanket (UASB) reactor. The application of the

UASB process to the direct treatment of sewage is reviewed, with examples from Europe, Asia and

the Americas. The UASB reactor appears today as a robust technology and is by far the most

widely used high-rate anaerobic process for sewage treatment.

2.7 The innovative Moving Bed Biofilm Reactor/ solids contact

reaeration process for secondary treatment of municipal wastewater

Bjorn Rusten et al. (1998) carried out an study on the innovative moving bed biofilm reactor/solids

con tact reaeration (MBBR/SCR) process has been chosen for a new waste water treatment plant

serving a population of 200 000 at Moa Point, Wellington, New Zealand. Because the MBBR/SCR

combination was new, a pilot-scale demonstration project was made part of the contract.

Thorough pilot tests using a wide range of organic loads under both steady and transient-flow

conditions demonstrated that the MBBR/SCR process produced the required effluent quality at

loads higher than used in the original design. At 3 days mean cell residence time (MCRT) in the

SCR stage, a final effluent with a 5-day biochemical oxygen demand (BOD5) of less than 10 mg/L

was achieved at an organic load on the MBBR of 15 g BOD5/ m2-d (5.0 kg BOD5/m3-d). With

the same MCRT, a final effluent of less than 15 mg BOD5/L was achieved at an organic load on

the MBBR of 20 g BOD5/m2 d (6.7 kg BOD5/m3 d).

Dynamic loading tests demon started that a good-quality effluent was produced with a diurnal

peak hour load on the MBBR of more than 40 g BOD5/m2 d (13.3 kg BOD5/ m3-d). The

MBBR/SCR process was more compact and significantly cheaper than a conventional trickling

filter/solids contact or activated-sludge process at the Moa Point site. Water Environ. Res., 70,

1083 (activated-sludge process at the Moa Point site. Water Environ. Res., 70, 1083 (1998).

16

2.8 Biological Fixed Film Systems

Mark W. Fitch et al. (1999) carried out a study in which the work reviewed here was published

during the catalogue/issue year 1999 and described research involving biofilms treating pollutants.

This review explicitly excludes research in medical biofilms, dental biofilms, biofilms causing

corrosion and biofilm formation in drinking water treatment and distribution systems. Anaerobic

biofilm treatment system research is not reviewed here although a set of references is provided.

However, the authors have included coverage of denitrification in traditional biofilm treatment

systems. Similarly, biofilm systems for the treatment of air pollutants is reviewed in the Gaseous

Emissions from Wastewater Facilities section of this issue.

2.9 The Moving Bed Bio film Reactor

H. Odegaard et al. (1999) studied a new biofilm reactor for wastewater treatment: The Moving

Bed Bio Film Reactor (MBBR). The result from the investigations of different applications

(Carbonaceous removal, nitrification removal and nitrogen removal) when used for municipal

wastewater treatment, are discussed, Design value are given and it is demonstrated that use of this

reactor results in very compact treatment plants.

2.10 Performance evaluation of a UASB – activated sludge system

treating municipal wastewater

M. von Sperling*, V.H. Freire and C.A. de Lemos Chernicharo (2001): Recent research has

indicated the advantages of combining anaerobic and aerobic processes for the treatment of

municipal wastewater, especially for warm-climate countries. Although this configuration is seen

as an economical alternative, is has not been investigated in sufficient detail on a worldwide basis.

This work presents the results of the monitoring of a pilot-scale plant comprising of an UASB

reactor followed by an activated sludge system, treating actual municipal wastewater from a large

city in Brazil. The plant was intensively monitored and operated for 261 days, divided into five

different phases, working with constant and variable inflows.

17

The plant showed good COD removal, with efficiencies ranging from 69% to 84% for the UASB

reactor, from 43% to 56% for the activated sludge system only and from 85% to 93% for the

overall system. The final effluent suspended solids concentration was very low, with averages

ranging from 13 to 18 mg/l in the typical phases of the research.

Based on the very good overall performance of the system, it is believed that it is a better

alternative for warm-climate countries than the conventional activated sludge system, especially

considering the total low hydraulic detention time (4.0 h UASB; 2.8 h aerobic reactor; 1.1 h final

clarifier), the savings in energy consumption, the absence of primary sludge and the possibility of

thickening and digesting the aerobic excess sludge in the UASB reactor itself.

2.11 Removal of slowly biodegradable COD in combined Thermophilic

UASB and MBBR System

M.Ji et al (2001) studied that Starch, cellulose and polyvinyl alcohol (PVA) are common substrates

of the slowly biodegradable COD (SBCOD) in industrial wastewaters. Removal of the individual

and mixed SBCOD substrates was investigated in a combined system of thermophilic upflow

anaerobic sludge blanket (TUASB) reactor (55°C) and aerobic moving bed biofilm reactor

(MBBR).

The removal mechanisms of the three SBCOD substrates were quite different. Starch-COD was

almost equally utilized and removed in the two reactors. Cellulose-COD was completely (97-98%)

removed from water in the TUASB reactor by microbial entrapment and sedimentation of the

cellulose fibers. PVA alone was hardly biodegraded and removed by the combined reactors.

However, PVA-COD could be removed to some extent in a binary solution of starch (77%) plus

PVA (23%).

The PVA macromolecules in the binary solution actually affected the microbial activity in the

TUASB reactor resulting accumulation of volatile fatty acids, which shifted the overall COD

removal from the TUASB to the MBBR reactor where SBCOD including PVA-COD was

removed. Since the three SBCOD substrates were removed by different mechanisms, the combined

reactors showed a better and more stable performance than individual reactors.

18

2.12 Anaerobic sewage treatment in a one-stage UASB reactor and a

combined UASB-Digester system

In an another study made by Nidal Mahmoud et al (2004) the treatment of sewage at 15°C was

investigated in a one-stage upflow anaerobic sludge blanket (UASB) reactor and a UASB-Digester

system. The latter consists of a UASB reactor complemented with a digester for mutual sewage

treatment and sludge stabilisation. The UASB reactor was operated at a hydraulic retention time of

6 h and a controlled temperature of 15°C, the average sewage temperature during wintertime of

some Middle East countries. The digester was operated at 35°C.

The UASB-Digester system provided significantly (significance level 5%) higher COD removal

efficiencies than the one-stage UASB reactor. The achieved removal efficiencies in the UASB-

Digester system and the one-stage UASB reactor for total, suspended, colloidal and dissolved

COD were 66%, 87%, 44% and 30%, and 44%, 73%, 3% and 5% for both systems, respectively.

The stability values of the wasted sludge from the one-stage UASB reactor and the UASB-Digester

system were, respectively, 0.47 and 0.36 g CH4-COD/g COD. Therefore, the anaerobic sewage

treatment at low temperature in a UASB-Digester system is promising.

2.13 Developments in wastewater treatment methods

Amit Sonune and Rupali Ghate (2004) studied that Wastewaters are waterborne solids and liquids

discharged into sewers that represent the wastes of community life. Wastewater includes dissolved

and suspended organic solids, which are “putrescible” or biologically decomposable. Two general

categories of wastewaters, not entirely separable, are recognized: domestic and industrial.

Wastewater treatment is a process in which the solids in wastewater are partially removed and

partially changed by decomposition from highly complex, putrescible, organic solids to mineral or

relatively stable organic solids. Primary and secondary treatment removes the majority of BOD

and suspended solids found in wastewaters. However, in an increasing number of cases this level

of treatment has proved to be insufficient to protect the receiving waters or to provide reusable

water for industrial and/or domestic recycling.

19

Thus, additional treatment steps have been added to wastewater treatment plants to provide for

further organic and solids removals or to provide for removal of nutrients and/or toxic materials.

There have been several new developments in the water treatment field in the last years.

Alternatives have presented themselves for classical and conventional water treatment systems.

Advanced wastewater treatments have become an area of global focus as individuals, communities,

industries and nations strive for ways to keep essential resources available and suitable for use.

Advanced wastewater treatment technology, coupled with wastewater reduction and water

recycling initiatives, offer hope of slowing, and perhaps halting, the inevitable loss of usable water.

Membrane technologies are well suited to the recycling and reuse of waste water. Membranes can

selectively separate components over a wide range of particle sizes and molecular weights.

Membrane technology has become a dignified separation technology over the past decennia.

The main force of membrane technology is the fact that it works without the addition of

chemicals, with relatively low energy use and easy and well-arranged process conduction. This

paper covers all advanced methods of wastewater treatments and reuse.

2.14 Potential of a Combination of UASB and DHS Reactor as a Novel

Sewage Treatment System for Developing Countries: Long-Term

Evaluation

In a study made by Madan Tandukar et al. (2006) A novel municipal wastewater treatment

system, consisting of a combination of an upflow anaerobic sludge blanket (UASB) and down-

flow hanging sponge (DHS) post treatment unit, was continuously evaluated for more than three

years with raw sewage as an influent. The system was installed at a sewage treatment site and

operated at 25±3°C.

This paper reports on the results of a long term monitoring of the system. The whole experimental

period was divided into three distinct phases with different operating conditions. Organic

pollutants were only partially removed in anaerobic UASB pretreatment unit. The remaining

organics as well as nitrogenous compounds were almost completely removed by the DHS post

treatment unit.

20

In all phases the system demonstrated removal efficiency consistently over 95% for unfiltered

biochemical oxygen demand (BOD), 80% for unfiltered-chemical oxygen demand and 70% for

suspended solids. The system produced an excellent effluent quality with only 4–9 mg∕L of

residual unfiltered BOD.

Dissolved oxygen in the final effluent was 5–7 mg∕L although no aeration was provided to DHS

system. Moreover, excess sludge production from DHS was negligible thus eliminating secondary

sludge that is troublesome to dispose off.

The system also exhibited substantial stability against twofold hydraulic shock load and fourfold

organic shock load. The results suggested that the proposed system may be a competitive solution

for municipal sewage treatment under variable conditions.

2.15 Treatment of pesticide wastewater by Moving-Bed Biofilm Reactor

combined with Fenton-coagulation pretreatment

Sheng et al.(2006), South Korea conducted the study In order to treat pesticide wastewater having

high chemical oxygen demand (COD) value and poor biodegradability, Fenton-coagulation

process was first used to reduce COD and improve biodegradability and then was followed by

biological treatment. Optimal experimental conditions for the Fenton process were determined to

be Fe2+ concentration of 40 mol/L and H2O 2 dose of 97 mol/L at initial pH 3.

The interaction mechanism of organophosphorous pesticide and hydroxyl radicals was suggested

to be the breakage of the P S double bond and formation of sulfate ions and various organic

intermediates, followed by formation of phosphate and consequent oxidation of intermediates. For

the subsequent biological treatment, 3.2 g/L Ca(OH)2 was added to adjust the pH and further

coagulate the pollutants.

The COD value could be evidently decreased from 33,700 to 9300 mg/L and the ratio of

biological oxygen demand (BOD5) to COD of the wastewater was enhanced to over 0.47 by

Fenton oxidation and coagulation. The pre-treated wastewater was then subjected to biological

21

oxidation by using moving-bed biofilm reactor (MBBR) inside which tube chip type bio-carriers

were fluidized upon air bubbling.

Higher than 85% of COD removal efficiency could be achieved when the bio-carrier volume

fraction was kept more than 20% by feeding the pretreated wastewater containing 3000 mg/L of

inlet COD at one day of hydraulic retention time (HRT), but a noticeable decrease in the COD

removal efficiency when the carrier volume was decreased down to 10%, only 72% was observed.

With the improvement of biodegradability by using Fenton pretreatment, also due to the high

concentration of biomass and high biofilm activity using the fluidizing bio-carriers, high removal

efficiency and stable operation could be achieved in the biological process even at a high COD

loading of 37.5 gCOD/(m2 carrier day).

2.16 Combined Anaerobic/Aerobic secondary municipal wastewater

treatment: Pilot-Plant demonstration of the UASB/Aerobic Solid

Contact System

Enrique J. La Motta et al. (2007) done a study in which Anaerobic pretreatment followed by

aerobic post treatment of municipal wastewater is being used more frequently. Recent

investigations in this field using an anaerobic fluidized bed reactor/aerobic solids contact

combination demonstrated the technical feasibility of this process. The investigation presented

herein describes the use of a combined upflow anaerobic sludge bed (UASB)/aerobic solids

contact system for the treatment of municipal wastewater and attempts to demonstrate the technical

feasibility of using the UASB process as both a pretreatment unit and a waste activated sludge

digestion system.

The results indicate that the UASB reactor has a total chemical oxygen demand removal efficiency

of 34%, and a total suspended solids removal efficiency of about 36%. Of the solids removed by

the unit, 33% were degraded by the action of microorganisms, and 4.6% accumulated in the

reactor. This low solids accumulation rate allowed operating the UASB reactor for three months

without sludge wasting.

22

The long solids retention time in this unit is comparable to the one normally used in conventional

sludge digestion units, thus allowing the stabilization of the waste activated sludge returned to the

UASB reactor.

Particle flocculation was very poor in the UASB reactor, and therefore, it required post aeration

periods of at least 100 min to proceed successfully in the aerobic unit. Polymer generation, which

is necessary for efficient biological flocculation, was practically nonexistent in the anaerobic unit;

therefore, it was necessary to maintain dissolved oxygen levels greater than 1.5 mg∕L in the aerobic

solids contact chamber for polymer generation to proceed at optimum levels. Once these

conditions were attained, the quality of the settled solids contact chamber effluent always met the

30 mg BOD/L, 30 mg SS/L secondary effluent guidelines.

2.17 Performance comparison of a pilot-scale UASB and DHS system and

activated sludge process for the treatment of municipal wastewater

Madan Tandukar et al. (2007), Japan made an study which compares the performance of a pilot-

scale combination of UASB and DHS system to that of activated sludge process (ASP) for the

treatment of municipal sewage. Both systems were operated in parallel with the same sewage as

influent. The study was conducted for more than 300 days, which revealed that organic removal

efficiency of UASB + DHS system was comparable to that of ASP. Unfiltered BOD removal by

both systems was more than 90%. However, UASB + DHS system outperformed ASP for

pathogen removal. In addition, volume of excess sludge production from UASB +DHS was 15

times smaller than that from ASP. Moreover, unlike ASP, there is no requirement of aeration for

the operation of UASB + DHS system, which makes it an economical treatment system.

Considering the above observations, it was concluded that UASB + DHS system can be a cost-

effective and viable option for the treatment of municipal sewage over ASP,

especially for low-income countries.

23

2.18 Efficiency evaluation of sewage treatment plant with different

technologies in Delhi (India)

Priyanka Jamwal and Atul k.Mittal (2008) carried out an study on Physical, chemical and

microbiological efficiencies of Sewage Treatment Plants (STPs) located in Delhi’s watershed in

context of different treatment technologies employed in these plants have been determined. There

were in all seventeen STPs treating domestic wastewater which were studied over a period of 12

months. These STPs were based on Conventional Activated sludge process (ASP), Extended

aeration (Ex. Aeration), physical, chemical and biological removal treatment (BIOFORE) and

oxidation pond treatment process.

Results suggests that except “Mehrauli” STP which was based on Extended aeration process and

“Oxidation pond”, effluents from all other STPs exceeded FC standard of 103 MPN/100 ml for

unrestricted irrigation criteria set by National river conservation directorate (NRCD). Actual

integrated efficiency (IEa) of each STP was evaluated and compared with the standard integrated

efficiency (IEs) based upon physical, biological and microbiological removal efficiencies

depending upon influent sewage characteristics. The best results were obtained for STPs

employing extended aeration, BIOFORE and oxidation pond treatment process thus can be safely

used for Irrigation purposes.

2.18 Treatment of domestic wastewater in an Up-Flow Anaerobic Sludge

Blanket reactor followed by Moving Bed Bio film Reactor

A.Tawfik et al. (2009), The Netherlands made an study to evaluate the performance of a

laboratory-scale sewage treatment system composed of an up-flow anaerobic sludge blanket

(UASB) reactor and a moving bed biofilm reactor(MBBR) at a temperature of (22–35 °C) . The

entire treatment system was operated at different hydraulic retention times (HRT’s) of 13.3, 10 and

5.0 h.

24

An overall reduction of 80–86% for COD total; 51–73% for COD colloidal and 20–55% for COD

soluble was found at a total HRT of 5–10 h, respectively. By prolonging the HRT to 13.3 h, the

removal efficiencies of COD total, COD colloidal and COD soluble increased up to 92, 89 and

80%, respectively.

However, the removal efficiency of COD suspended in the combined system remained unaffected

when increasing the total HRT from 5 to 10 h and from 10 to 13.3 h. This indicates that, the

removal of COD suspended was independent on the imposed HRT. Ammonia-nitrogen removal in

MBBR treating UASB reactor effluent was significantly influenced by organic loading rate (OLR).

62% of ammonia was eliminated at OLR of 4.6 g COD m-2 day-1.

The removal efficiency was decreased by a value of 34 and 43% at a higher OLR’s of 7.4 and 17.8

g COD m-2 day-1, respectively. The mean overall residual counts of faecal coliform in the final

effluent were 8.9 9 104 MPN per 100 ml at a HRT of 13.3 h, 4.9 9 105 MPN per 100 ml at a HRT

of 10 h and 9.4 9 105 MPN per 100 ml at a HRT of 5.0 h, corresponding to overall log10 reduction

of 2.3, 1.4 and 0.7, respectively.

The discharged sludge from UASB–MBBR exerts an excellent settling property. Moreover, the

mean value of the net sludge yield was only 6% in UASB reactor and 7% in the MBBR of the total

influent COD at a total HRT of 13.3 h. Accordingly, the use of the combined UASB–MBBR

system for sewage treatment is recommended at a total HRT of 13.3 h.

2.20 Assessment of the efficiency of Sewerage Treatment Plants

In another study made by Ravi Kumar et al. (2010), Bangalore, Bangalore city hosts two Urban

Wastewater Treatment Plants (UWTPs) towards the periphery of Vrishabhavathi valley, located in

Nellakedaranahalli village of Nagasandra and Mailasandra Village, Karnataka, India. These plants

are designed and constructed with an aim to manage wastewater so as to minimize and/or remove

organic matter, solids, nutrients, disease-causing organisms and other pollutants, before it reenters

a water body.

25

It was revealed from the performance study that efficiency of the two treatment plants was poor

with respect to removal of total dissolved solids in contrast to the removal/reduction in other

parameters like total suspended solids, BOD and COD.

In Mailasandra STP, TDS, TSS, BOD, and COD removal efficiency was 20.01, 94.51, 94.98 and

76.26 % and respectively, while in Nagasandra STP, TDS, TSS, BOD, and COD removal

efficiency was 28.45, 99.0, 97.6 and 91.60 % respectively.

The order of reduction efficiency was

TDS < COD < TSS < BOD and TDS < COD < BOD < TSS respectively in Mailasandra and

Nagasandra STPs. Additionally, the problems associated with the operation and maintenance of

wastewater treatment plants is discussed.

2.21 Biofilms in Water and Wastewater treatment

Rakmi Abd.Rahman et.al (2010) studied that Biofilm reactors are increasingly used to treat

industrial effluents with difficult components, this type of process has been applied to wastewaters

containing various types of pollutants, such as those containing chlorinated organics. These have

not been effectively removed by conventional activated sludge types of processes due to their

recalcitrance. Biofilm reactors have biomass active even at very low concentrations of the target organics,

rendering the reactor more efficient for removing trace toxic compounds in wastewaters.

Biofilm processes, having high biomass concentrations, have also been found to be less sensitive

to the presence of toxic and inhibitory materials, and more resistant to shock loadings than the

dispersed growth systems. Such characteristics are essential where floor space is becoming

expensive and yet there is great need to treat and polish effluents before reuse.

With increasing pollution of rivers by trace industrial and household chemicals and

pharmaceuticals, and greater demands for water, the difference between effluent polishing and

water treatment is diminishing. With increasing knowledge of health effects of trace pollutants, a

more effective yet affordable water treatment system than the conventional system has to be

investigated. The conventional water treatment system of coagulation, settling and filtration,

26

removes mainly suspended solids; trace and recalcitrant organics would pass through the system.

Greater use of groundwater and stricter drinking water limits, such as the new EU Drinking Water

Directive (EU DWD), has established the use of biofilm processes in water treatment, such as in

northern Italy.

Results of on-going research on use of biofilm processes for water and wastewater treatment are

reported here. These are uses of biofilm columns for river water treatment and rainwater polishing,

and use of biofilm columns for removal of chloroorganics and heavy metals. In all these studies the

biofilm columns have been found very effective for treatment of river waters for removal of

organics and nutrients, and treatment of wastewaters, for removal of chloroorganics and heavy

metals.

Metabolite analysis indicated biodegradation of PCP reductive dechlorination had occurred in the

reactor, showing that biofilms offered both oxidative and reductive conditions. Besides these

special characteristics, no chemicals were employed in both water and wastewater biofilm

treatments. Thus no chemical sludge was generated, besides lowering treatment costs due to

chemicals. Biofilm processes as used here have potential to be further developed into cheaper,

environmentally friendlier processes for treating water and wastewaters containing organics and

heavy metals.

2.22 Comparison of overall performance between "Moving-Bed" and

"Conventional" Sequencing Batch Reactor

E. Hosseini Koupaie et al. (2011) carried out a studied in which the main objective of the work was

to compare the overall performances of "moving-bed" and "conventional" sequencing batch

reactor. For this purpose, different experimental parameters including COD and dye concentration,

turbidity, MLSS concentration, MLVSS/MLSS ratio, sludge volume index (SVI) and Oxidation-

Reduction Potential (ORP) were calculated.

27

One conventional sequencing batch reactor and three moving-bed sequencing batch reactors (MB-

SBR) were operated in this study. Each MB-SBR was equipped with a type of moving biofilm

carrier.

The results of dye, COD and turbidity analysis showed that there were no significant differences

between the moving-bed and conventional sequencing batch reactors in the matters of effluent

quality. A higher fluctuation of MLSS concentration and also higher SVI were observed in

moving-bed compared to that of the conventional sequencing batch reactor. Higher ORP values

which mean higher oxidation potential were measured in the reactors equipped with the moving

carriers in comparison with those measured in the conventional sequencing batch reactor.

2.23 Integrated application of Upflow Anaerobic Sludge Blanket Reactor

for the treatment of wastewaters

Muhammad Asif Latif et al (2011) observed that, the UASB process among other treatment

methods has been recognized as a core method of an advanced technology for environmental

protection. This paper highlights the treatment of seven types of wastewaters i.e. palm oil mill

effluent (POME), distillery wastewater, slaughterhouse wastewater, piggery wastewater, dairy

wastewater, fishery wastewater and municipal wastewater (black and gray) by UASB process. The

purpose of this study is to explore the pollution load of these wastewaters and their treatment

potential use in upflow anaerobic sludge blanket process.

The general characterization of wastewater, treatment in UASB reactor with operational

parameters and reactor performance in terms of COD removal and biogas production are

thoroughly discussed in the paper. The concrete data illustrates the reactor configuration, thus

giving maximum awareness about upflow anaerobic sludge blanket reactor for further research.

The future aspects for research needs are also outlined.

28

2.24 Sustainable options of post treatment of UASB effluent treating sewage:

A review

Abid Ali Khan et al. (2011) studied that upflow anaerobic sludge blanket (UASB) process is

reported to be a sustainable technology for domestic wastewaters treatment in developing countries

and for small communities. However, the inability of UASB process to meet the desired disposal

standards has given enough impetus for subsequent post treatment. In order to upgrade the UASB

based sewage treatment plants (STPs) to achieve desired effluent quality for disposal or for reuse,

various technological options are available and broadly differentiated as primary post-treatment for

the removal of organic and inorganic compounds and suspended matter; secondary post-treatment

for the removal of hardly degradable soluble matter, colloidal and nutrients; and polishing systems

for removals of pathogens.

Hence, this paper discusses the different systems for the treatment of UASB reactor effluent

treating sewage. Additionally, a comparative review, an economic evaluation of some of the

emerging options was conducted and based on the extensive review of different integrated

combination, i.e. UASB-different aerobic systems, a treatment concept based on natural biological

mineralization route recognized as an advanced technology to meet all practical aspects to make it

a sustainable for environmental protection, resource preservation and recovering maximum

resources.

2.25 Upgrading Activated Sludge Systems and reduction in excess sludge

Hossein Hazrati and Jalal Shayegan (2011) studied on activated sludge systems they found that

Most of 200 Activated Sludge Plant in Iran are overloaded and as a result, their efficiency is low.

In this work, a pilot plant is manufactured and put into operation in one of the wastewater

treatment plants in the west of Tehran.

Instead of conventional activated sludge, a membrane bioreactor and an upflow anaerobic sludge

blanket reactor used as a pretreatment unit in this pilot. For the sake of data accuracy and

precision, an enriched municipal wastewater was opted as an influent to the pilot. Based on the

attained result, the optimum retention time in this system was 4 h, and the overall COD removal

efficiency was 98%.

29

As a whole, the application of this retrofit would increase the plant’s capacity by a factor of 5 and

reducing the excess sludge by a factor of 10. The sludge volume index in the anaerobic reactor was

about 12 after granulation occurred.

2.26 Improvements in Biofilm Processes for Wastewater Treatment

Husham T. Ibrahim et al. (2012) made an effort in this review paper which intends to provide an

overall vision of biofilm technology as an alternative method for treating waste waters. This

technology has been gaining popularity through the years, mainly because many wastewater

treatment plants, which are still used Activated Sludge Process (AS) are present some

shortcomings when exposed to increased hydraulic and organic loads.

Fundamental research into biofilms is presented in three sections, Biofilm Types and

Characterization, Advantages and Drawbacks and Design Parameters. The reactor types covered in

this review are: un-submerged fixed film systems (trickling filters and rotating biological

contactors) and submerged fixed film systems (biological aerated flooded filters, submerged

aerated filters, biofilm up-flow sludge blanket, fluidized bed, expanded granular sludge blanket,

biofilm airlift suspension, internal circulation, moving bed biofilm and membrane biofilm)

reactors.

2.27 Performance evaluation of Moving Bed Bio-Film Reactor technology

for treatment of domestic waste water in Industrial Area at MEPZ

(Madras Exports Processing Zone), Tambaram, Chennai, India

Ravichandran.M and Joshua Amarnath.D (2012) carried out a study on MEPZ, an industrial unit

installed at Tambaram, Chennai, developed by the Ministry of Commerce and Industries,

Government of India is discharging domestic waste water generated by the workers and treated in

the 1.0MLD capacity Sewage Treatment Plant with Moving Bed Bio-film Reactor.

30

In this study, the performance of MBBR technology in removal of Biological Oxygen Demand

and suspended Solids have been evaluated by testing the raw sewage and treated effluent at various

situations like normal weather condition, heavy organic shock loading, dilution with storm water,

when artificial aeration is disturbed due to power failure.

The test results showed that the removal efficiency of BOD5 and SS from the domestic waste

water in normal weather condition in more than 98%, the efficiency of MBBR has not been

affected due to heavy Organic shock loading and the efficiency is about 90% in the disturbance of

artificial aeration.

The efficiency has been brought to this level by improving the surface area per unit volume of the

carrier element as designed by the M/s Anox Kaldnes, a Norway company. It is suggested that the

Moving Bed Bio-film Reactor technology could be used an ideal and efficient option for the

treatment of domestic waste water, when the available area is minimum.

2.28 The performance enhancements of Upflow Anaerobic Sludge Blanket

(UASB) reactors for domestic sludge treatment – A State of the art review

Siewhui Chong et al. (2012) made a study in which he found that Nowadays, carbon emission and

therefore carbon footprint of water utilities is an important issue. In this respect, we should

consider the opportunities to reduce carbon footprint for small and large wastewater treatment

plants.

The use of anaerobic rather than aerobic treatment processes would achieve this aim because no

aeration is required and the generation of methane can be used within the plant. High-rate

anaerobic digesters receive great interests due to their high loading capacity and low sludge

production. Among them, the upflow anaerobic sludge blanket (UASB) reactors have been most

widely used.

31

However, there are still unresolved issues inhibiting the widespread of this technology in

developing countries or countries with climate temperature fluctuations (such as subtropical

regions). A large number of studies have been carried out in order to enhance the performance of

UASB reactors but there is a lack of updated documentation.

2.29 Wastewater Treatment in Baghdad City Using Moving Bed

Biofilm Reactor (MBBR) technology

Mohammed A. Abdul-Majeed et al. (2012) conducted a study in which, a laboratory scale system

of Moving Bed Biofilm Reactor (MBBR) was used to treat municipal wastewater from a domestic

community in Baghdad City to get the water free from BOD for reuse in the irrigation or discharge

to the river.

The aim of the described experimentation was the comparison of a low cost MBBR and an

activated sludge system (AS); the other aim from this research is to derive successful MBBR

wastewater reuse projects in Iraq. Laboratory experiments were conducted in two parts, firstly at

BOD5 load of about (150-200) mg/l, filling ratio of plastic elements in the MBBR reactor was

40%. Aerobic reactor consumed most of the biodegradable organic matter.

The BOD5 removal efficiencies were 78 and 90% for MBBR & AS respectively. Second part when

BOD5 load about (900-1300) mg/l used (synthetic wastewater)، filling ratio is 67%. The removal

efficiencies of BOD reached 73 % for AS and about 88% for MBBR.

2.30 A review of the Upflow Anaerobic Sludge Blanket Reactor

Chidozie Charles Nnaji (2013) conducted a study in which the upflow anaerobic sludge blanket

(UASB) reactor has found wide acceptance in the treatment of industrial wastewaters since its

development in the Netherlands.

32

It has been applied to a wide spectrum of wastewaters on both domestic and industrial scales.This

acceptance stems from its simplicity, economy and the possibility of energy recovery. Studies

focusing on UASB reactors are numerous; and though conflicting results have been observed,

researchers are unanimous when it comes to the efficiency of the reactor in the treatment of high-

to medium-strength wastewaters with easily hydrolysable substrate.

It has also recorded a level of success in sewage treatment in tropical countries. As much, success

has not been recorded in cold climates and in the treatment of wastewaters containing complex or

toxic substance. The efforts of numerous researchers have given rise to many variants and

modifications of the UASB reactor, which have widened the scope of applicability of this very

important facility.

This paper presents a concise but comprehensive review of the UASB reactor and studies focusing

on it. Key operational issues such as granulation, methanogenesis, hydraulic retention time,

efficiency, toxicity, modifications of UASB reactors and biogas recovery were considered using

facts and data sieved from literature. This review shows that UASB reactors can be adapted for the

treatment of almost any type of wastewater if modified accordingly.

33

CHAPTER 3

MATERIALS AND METHODOLOGY

3.1 Selection of Sites and Sampling Points

Samples for analysis were collected from the three STP’s mentioned above namely:

1. Raipur Kalan STP

2. Raipur Khurd STP

3. “Diggian” Mohali STP

The major area from which samples were collected i.e the sampling points were:

1. Inlet and Final Outlet of Raipur Kalan STP

2. Inlet and Final Outlet of Raipur Khurd STP

3. Inlet and Final Outlet of “Diggian” Mohali STP

3.2 Collection of Samples

Grab Samples were collected as per APHA- Standard Methods for Examination of Water and

Wastewater. Samples were collected 3 times, one each, in month of FEBRUARY, MARCH and

APRIL during the duration of study.

3.3 Parameters Analyzed

1. Physico-chemical parameters

The parameters analyzed in this study were pH, Temp (Temperature), TSS (Total Suspended

Solids), TDS (Total Dissolved Solids), Oil and Grease, chlorides and Chemical Oxygen Demand

(COD).

2. Biological parameters

The biological parameters analyzed in present study included Biochemical Oxygen Demand

(BOD).

34

3. Nutrient Load

The Nutrients analysed in this study were Nitrate-Nitrogen (NO3 –N), Ammonical Nitrogen (NH3 –

N) and Phosphate (PO4-)

Table 3.1: Parameters and Methods for their Analysis

PARAMETER TEST METHOD

pH Electrometric

Temperature Digital Thermometer

Oil and Grease Soxhlet Extraction

Total Suspended Solids Membrane Filtration

Total Dissolved Solids Gravimetric

Biochemical Oxygen demand Winkler’s Titration

Chemical Oxygen Demand Closed Reflux Titrimetry

Chlorides Argentometric Titration

Nitrate – Nitrogen Acid Treatment followed by Spectrophotometry

Ammonical – Nitrogen Distillation Titrimetric

Phosphate Ascorbic Acid Spectrophotometry

35

Laboratories used for Parameters Analysis

1. STP “Diggian” Mohali Laboratory

2. Environ Tech Laboratories , Industrial Area, Phase -7, S.A.S. Nagar (Mohali

Punjab)

3. 39 - Water Works Laboratory, Sector – 39, Chandigarh

3.4 Methods for Parameters Analysis

pH

Method: Electrometric method was adopted for the determination.

Procedure

Standardize the pH meter by immersing the electrode in a buffer solution of known pH,

normally 4 and 9.

Read the pH and calibrate, till it indicates the correct value for pH of buffer solution. Rinse

the electrode in distilled water and immerse them in sample.

Read the pH value.

Fig 3.1: pH Apparatus

36

Temperature (Temp)

Method: Digital Thermometer was used for analysis of temperature.

Procedure

Take 100 mL of sample in a beaker.

Put Digital Thermometer in the beaker containing sample.

The instrument will show the reading related to temperature in oC.

Fig 3.2: Digital Thermometer

Oil and Grease

Method: Soxhlet Extraction Method

Procedure

37

Prepare filter consisting of a Muslin cloth disc overlaid with filter paper. Wet the cloth and

paper.

Pass 100 mL of filter aid suspension through the prepared filter using vacuum and wash

with 1 litre of distilled water. Filter the acidified sample.

Apply vacuum until no more liquid sample passes through filter paper.

Using forceps transfer the filter paper to a watch glass. Add material adhering to edges of

muslin cloth disc.

Wipe sides and bottom of collection vessel and Buchner funnel with filter paper soaked in

solvent, taking care to remove all films caused by grease and to collect all the solids

material.

Add pieces of filter paper on watch glass. Roll all filter papers containing sample and put

into an extraction thimble.

Add any piece of material remaining on watch glass. Wipe the watch glass with filter paper

soaked in solvent and place it in the thimble.

Dry the thimble at 1030C for 30 minutes in an oven. Fill the thimble with glass whool or

small glass beads.

Weigh the extraction flask and extract oil and grease in Soxhlet Apparatus, using hexane at

a rate of 20 cycles per hour for 4 hours counting first cycle.

Place the flask on a water bath at 700C for 15 minutes and draw air through it by vacuum

for final 1 minute

Cool, in desiccators for 30 minutes and weigh.

Calculation

Oil and Grease, mg/L = M x 1000

Where,

M = Mass, in mg, of the residue

V = Volume in ml of the sample taken for test

V

38

Fig 3.3: Soxhlet Apparatus

Total Suspended Solids (TSS)

Method: Membrane filtration Method

Procedure

Take 50 mL of sample in Gooch crucible.

Place the Gooch crucible on the glass fiber apparatus.

Switch on the electrical supply.

39

Liquid passes in the glass fiber.

Solids remains on the Asbestos layer.

Weigh the empty Gooch crucible before the experiment and after drying the crucible at

about 1030c in a oven to 15 mins.

Calculation

Total Suspended Solids =

(Weight of Gooch Crucible + Residue) - (Weight of empty Gooch Crucible )

Volume of sample Taken

Gooch Crucible

Χ 1000

40

Fig 3.4: Glass Fibre apparatus for Total Suspended Solids (TSS)

Total Dissolved Solids (TDS)

Method: Gravimetrically after drying in an oven

Procedure

Filter paper is washed by inserting it in the filtration assembly and filtering 3 successive 20

mL portions of distilled water. Suction is continued to remove all traces of water. Washings

are discarded.

Evaporating dish is dried at 104 ± 10C for 1 h, cooled and stored in desiccator. It is weighed

immediately before use.

Sample is stirred with a magnetic stirrer and while stirring a measured volume is pipette on

to the filter using a wide bore pipette. Sample volume is chosen to yield between 10 and

200 mg dried residue. Then washed with three successive 10 mL volumes of distilled

water. Suction is continued for about 3 min after filtration is complete.

41

Total filtrate is transferred with washings to a weighed evaporating dish and evaporated to

dryness in an oven at 104 ± 10C. If necessary successive portions are added to the same

dish after evaporation in order to yield between 10 and 200 mg dried residue. To prevent

splattering oven temperature may be lowered initially by 20C below boiling point and

raised to 104 0C after evaporation for 1h. Then cooled in a desiccator and weighed.

Calculation

Where:

A = Weight of dried residue + dish, mg

B = Weight of dish, mg.

Biochemical Oxygen Demand (BOD)

METHOD: Winkler’s Titration

Procedure

Prepare dilution water by adding 1mL each of phosphate buffer, Magnesium

sulphate solution, Calcium chloride and ferric chloride solution to 1 liter distilled

water.

Determine the exact capacity of three BOD bottles. Find out the D.O of undiluted sample

and designate as DOS.

Prepare the desired percent mixture by adding samples in dilution water.

Fill up one bottle with the mixture and the other one with dilution water blank.

Incubate at a fix temperature for 27C, 3 days.

42

Find out DO in both bottles after incubation and designate mixture as DOi, blank as DOb.

Calculation

BOD3, 27 C (mg/L) = [(DOB - DOi) D.F – (DOb- DOS)]

Where,

DOB = DO of blank solution (dilution water)

DOb = DO of incubated blank solution

DOi = DO of incubated diluted sample

DOS = DO of undiluted sample (sample)

D.F = dilution factor = Total vol. of sample + Blank

mL of Sample

Fig 3.5: BOD Incubator

43

Chemical Oxygen Demand (COD)

METHOD: Closed Reflux Titrimetry

Procedure

Take 50 mL of sample or a smaller amount dilute to 50.0ml in a refluxing flask.

Add 1g of HgSO4 and 5 mL of H2SO4 (in which 1gm of silver sulphate is present in every

75ml acid).

Add slowly to dissolve HgSO4. Cool the mixture. Add 25.0 mL 0.25N K2Cr2O7 solution

and again mix. Attach the condenser and start the cooling water.

Add the remaining acid agent 70 mL through the open end of the condenser, mix the reflux

mixture. Apply the heat and reflux the mixture for 2hr and cool.

Dilute the mixture to about 300 mL and titrate excess of dichromate with standard ferrous

ammonium sulphate using Ferroin indicator. The color changes from yellow to green blue

and finally red. Record the mL of titrant used.

Reflux in the same manner a blank consisting of distilled water, equal to the volume of

sample and the reagents. Titrate as for sample. Record the ml of titrant used.

Calculation

COD = (A-B)C x 8x 1000

mL Sample

where, A = mL of Ferrous ammonium sulphate used for blank.

B = mL of Ferrous ammonium sulphate used for sample.

C = normality of ferrous ammonium sulphate solution.

44

Chloride (Cl -)

Method: Argentometric Titration

Procedure

Take 100 mL of sample in conical flask.

Add 1mL of Potassium chromate indicator. Sample colour turns Yellow.

Titrate with standard N/35.5 AgNO3 solution till the colour changes from yellow to brick

red. Note the amount of titrant used.

Calculation

Chlorides as Cl - = mL of AgNO3 used for sample x 1000

mL of sample

NITRATE – NITROGEN (NO3 –N)

Method: Acid Treatment followed by Spectrophotometry

Procedure

Treatment of sample: 1 mL HCl is added to 50 mL clear/filtered sample, mixed.

Preparation of standard curve: Calibration standards are prepared in the range of 0-7 mg

NO3--N/L, by diluting to 50 mL , 1 mL of HCl is added and mixed.

45

Spectrophotometric measurements: Absorbance or transmittance is read against re-distilled

water set at zero absorbance or 100 % transmittance. A wavelength of 220 nm is used to

obtain NO3- reading and a wavelength of 275nm to determine interference due to dissolved

organic matter.

Calculation

For sample and standards, 2 times the absorbance reading at 275nm is subtracted, from the

reading at 220nm to obtain absorbance due to NO3-. A standard curve is prepared by

plotting absorbance due to NO3- against NO3

--N concentration of standards. Sample

concentrations are obtained directly from standard curve, by using corrected sample

absorbance.

Fig 3.6: Spectrophotometer

46

Fig 3.7: Spectrophotometer Showing Standard Curve

Ammonical- Nitrogen (NH3 –N)

Method: Distillation Titrimetric Method

Procedure

Preparation of equipment: 500 mL water and 20 mL borate buffer are added,pH is adjusted

to 9.5 with 6N NaOH solution, and added to a distillation flask. A few glass beads or

boiling chips are added and this mixture is used to steam out distillation apparatus.

500 mL dechlorinated sample or a known portion diluted to 500 mL is used. The

following table is used to decide on sample volume.

47

25 mL borate buffer is added and pH is adjusted to 9.5 with 6N NaOH using a pH meter.

It is distilled at a rate of 6 to 10 mL/min with the tip of the delivery tube below the surface

of 50 mL indicting boric acid in a 500 mL Erlenmeyer flask. At least 200 mL distillate is

collected. The distillate-receiving flask is lowered in the last minute or two to clean

condenser and suction of the distillate is avoided into the condenser when the heater is

turned off.

Ammonia is titrated in distillate with 0.02 N H2SO4titrant until indicator turns pale

lavender.

A blank is carried through all steps and necessary correction is applied to the results.

Calculation

where:

A = mL H2SO4 titrated for sample

B = mL H2SO4 titrated for blank

48

Phosphate (PO4- )

Method: Ascorbic Acid Spectrophotometry

Procedure

Treatment of sample: 50 mL sample is taken into a 125 mL conical flask and 1 drop of

phenolphthalein indicator is added. Any red colour is discharged by adding 5N H2SO4. 8

mL combined reagent is added and mixed.

After 10 minutes, but no more than 30 minutes, absorbance of each sample is measured at

880nm. Reagent blank is used as reference.

Correction for turbid or coloured samples: A sample blank is prepared by adding all

reagents except ascorbic acid and potassium antimonyl tartrate to the sample. Blank

absorbance is subtracted from sample absorbance reading.

Preparation of calibration curve: Calibration from a series of standards between 0.15-1.30

mg P/L range (for a 1 cm light path) is prepared. Distilled water blank is used with the

combined reagent.

A graph with absorbance versus phosphate concentration is plotted to give a straight line.

At least one phosphate standard is tested with each set of samples.

Calculation

49

Table 3.2: Central Pollution Control Board (CPCB) General Standards for the

Discharge of Environmental Pollutants according to The Environment

(Protection) Rules, 1986 Schedule-VI Part –A: Effluents

Parameter

Inland

surface

water

Public

sewers

Land for

irrigation

Marine/Coastal

areas

Colour and

odour- - - -

Suspended

solids mg/l,

max.

100 600 200

(a) For process

waste water

(b) For cooling

water effluent 10

per cent above

total suspended

matter of

influent.

Particle size of

suspended

solids

shall pass

850 micron

IS Sieve

- -

(a) Floatable

solids, max. 3

mm

(b) Settleable

solids, max 856

microns

pH value 5.5 to 9.0 5.5 to 9.0 5.5 to 9.0 5.5 to 9.0

50

Temperature

shall not

exceed 5°C

above the

receiving

water

temperature

shall not exceed

5°C above the

receiving water

temperature

Oil and grease,

mg/l max,10 20 10 20

Total residual

chlorine, mg/l

max

1.0 - - 1.0

Ammonical

nitrogen as N;

mg/l, max.

50 50 - 50

Total kjeldahl

nitrogen (as

N);mg/l, max.

mg/l, max.

100 - - 100

Free ammonia

(as NH3),

mg/l,max.

5.0 - - 5.0

Biochemical

oxygen demand

(3 days at

27°C), mg/l,

max.

30 350 100 100

51

Chemical

oxygen demand,

mg/l, max.

250 - - 250

Arsenic (as As). 0.2 0.2 0.2 0.2

Mercury (As

Hg), mg/l, max.0.01 0.01 - 0.01

Lead (as Pb)

mg/l, max0.1 1.0 - 2.0

Cadmium (as

Cd) mg/l, max2.0 1.0 - 2.0

Hexavalent

chromium (as

Cr + 6), mg/l,

max.

0.1 2.0 - 1.0

Total chromium

(as Cr) mg/l,

max.

2.0 2.0 - 2.0

Copper (as Cu)

mg/l, max.3.0 3.0 - 3.0

52

Zinc (as Zn)

mg/l, max.5.0 15 - 15

Selenium (as

Se)0.05 0.05 - 0.05

Nickel (as Ni)

mg/l, max.3.0 3.0 - 5.0

Cyanide (as

CN) mg/l, max.0.2 2.0 0.2 0.2

Fluoride (as F)

mg/l, max.2.0 15 - 15

Dissolved

phosphates (as

P),mg/l, max.

5.0 - - -

Sulphide (as S)

mg/l, max.2.0 - - 5.0

Phenolic

compounds (as

C6H50H)mg/l,

max.

1.0 5.0 - 5.0

53

Radioactive

materials:

(a) Alpha

emitters micro

curie mg/l, max.

(b)Beta emitters

micro curie

mg/l

10 -7

10 -6

10 -7

10 -6

10 -8

10 -7

10 -7

10 -6

Bio-assay test

90%

survival of

fish after 96

hours in

100%

effluent

90%

survival

of fish

after 96

hours in

100%

effluent

90%

survival

of fish

after 96

hours in

100%

effluent

90% survival of

fish after 96

hours

in 100% effluent

Manganese 2 mg/l 2 mg/l - 2 mg/l

Iron (as Fe) 3mg/l 3mg/l - 3mg/l

Vanadium (as

V)0.2mg/l 0.2mg/l - 0.2mg/l

Nitrate Nitrogen 10 mg/l - - 20 mg/l

54

CHAPTER 4

RESULTS AND DISCUSSIONS

4.1 RESULTS

Concentration in mg/L, for all parameters except pH and Temp (C)

Table 4.1: Characteristics of INFLUENT and EFFLUENT of all the 3 STP’s in

the month of FEBRUARY

Parameters

Raipur Kalan STP

(UASB Technology)

Raipur Khurd STP

(ASP Technology)

Mohali STP

(MBBR

Technology)

Influent Effluent Influent Effluent Influent Effluent

Ph 7.9 8.6 7.8 8.4 7.6 8.1

Temp 18.4 18.1 18.6 18.0 18.3 17.9

TSS 159.0 38.0 168.0 63.0 172.0 30.0

TDS 283.0 160.0 285.0 169.0 291.0 106.0

Oil and Grease 3.7 0.4 4.5 0.3 5.2 0.2

BOD3, 27 C 154.0 34.0 140.0 37.0 184.0 17.0

COD 367.0 196.0 395.0 78.0 371.0 56.0

Cl- 192.0 88.0 118.0 98.8 168.0 106.0

NO3 -N 1.7 1.4 2.4 1.5 3.3 1.2

NH3 –N 28.7 30.3 25.3 28.1 19.7 24.5

PO4- 14.9 3.8 20.2 3.9 24.8 1.4

Temperature of Ghaggar river at the time of results calculated in February

was 19.2 C

55

Table 4.2: Characteristics of INFLUENT and EFFLUENT of all the 3 STP’s

in the month of MARCH

Parameters

Raipur Kalan STP

(UASB Technology)

Raipur Khurd STP

(ASP Technology)

Mohali STP

(MBBR

Technology)

Influent Effluent Influent Effluent Influent Effluent

pH 7.8 8.3 8.4 8.9 7.8 8.4

Temp 24.7 23.0 24.8 22.0 23.8 22.3

TSS 126.0 29.0 238.0 155.0 150.0 39.0

TDS 292.0 173.0 312.0 122.0 299.0 140.0

Oil and Grease 2.4 0.2 3.6 0.7 4.7 0.9

BOD3, 27 C 166.0 32.0 151.0 47.0 187.0 27.0

COD 349.0 105.0 379.0 99.0 357.0 63.0

Cl- 181.0 57.0 111.0 79.0 174.0 199.0

NO3 -N 2.8 1.3 4.1 1.4 4.9 1.4

NH3 –N 29.7 38.3 34.8 29.5 21.6 17.6

PO4- 19.4 5.2 15.2 7.8 15.9 1.96

Temperature of Ghaggar river at the time of results calculated in March was

27.4 C

56

Table 4.3: Characteristics of INFLUENT and EFFLUENT of all the 3 STP’s in

the month of APRIL

Parameters

Raipur Kalan STP

(UASB Technology)

Raipur Khurd STP

(ASP Technology)

Mohali STP

(MBBR

Technology)

Influent Effluent Influent Effluent Influent Effluent

pH 6.8 7.7 6.9 7.7 7.2 7.6

Temp 26.3 27.4 26.9 27.7 26.1 26.5

TSS 134.0 30.0 141.0 51.0 149.0 32.0

TDS 237.0 157.0 229.0 147.0 254.0 131.0

Oil and grease 2.9 0.6 3.8 0.9 3.3 0.4

BOD3, 27 C 179.0 35.0 149.0 31.0 189.0 26.0

COD 299.0 144.0 358.0 72.0 312.0 84.0

Cl- 169.0 53.0 147.0 33.0 158.0 113.0

NO3 -N 4.7 3.2 5.9 2.3 5.2 2.4

NH3 –N 19.5 28.8 23.2 37.8 17.5 23.6

PO4- 11.6 5.5 17.3 4.1 13.5 2.9

Temperature of Ghaggar river at the time of results calculated in APRIL was

32.6 C

57

Table 4.4: Average characteristics of INFLUENT and EFFLUENT of all the 3

STP’s

Parameters

Raipur Kalan STP

(UASB Technology)

Raipur Khurd STP

(ASP Technology)

Mohali STP

(MBBR

Technology)

Influent Effluent Influent Effluent Influent Effluent

pH 7.5 8.2 7.7 8.3 7.5 8.0

Temp 23.1 22.8 23.4 22.5 22.7 22.1

TSS 139.6 32.3 182.3 89.6 157.0 33.6

TDS 270.6 163.3 275.3 146.0 281.3 125.6

Oil and grease 3.0 0.4 3.9 0.6 4.4 0.5

BOD3, 27 C 166.3 33.6 146.6 38.3 186.6 23.3

COD 338.3 148.3 377.3 83.0 346.6 67.6

Cl- 180.6 66.0 125.3 70.0 166.6 139.3

NO3 -N 3.1 1.9 4.1 1.7 4.4 1.6

NH3 –N 25.9 32.4 27.7 31.8 19.6 21.9

PO4- 15.3 4.8 17.5 5.0 18.1 2.1

Average Temperature of Ghaggar river at the time of results calculated in

FEB, March and APRIL was 26.4 C

58

Graphical Representation of Average characteristics of INFLUENT and

EFFLUENT of all the 3 STP’s

X- Axis: Influent and Effluent

Y- Axis: Concentration in mg/L, for all parameters except pH and Temp (C)

Fig 4.1: Graphical Representation of pH

Fig 4.2: Graphical Representation of Temp

7

7.2

7.4

7.6

7.8

8

8.2

8.4

Influent

Raipur Kalan STP(UASB Technology)

21

21.5

22

22.5

23

23.5

Influent

Raipur Kalan STP(UASB Technology)

58

Graphical Representation of Average characteristics of INFLUENT and

EFFLUENT of all the 3 STP’s

X- Axis: Influent and Effluent

Y- Axis: Concentration in mg/L, for all parameters except pH and Temp (C)

Fig 4.1: Graphical Representation of pH

Fig 4.2: Graphical Representation of Temp

Influent Effluent Influent Effluent Influent Effluent

Raipur Kalan STP(UASB Technology)

Raipur Khurd STP (ASPTechnology)

Mohali STP (MBBRTechnology)

Influent Effluent Influent Effluent Influent Effluent

Raipur Kalan STP(UASB Technology)

Raipur Khurd STP (ASPTechnology)

Mohali STP (MBBRTechnology)

58

Graphical Representation of Average characteristics of INFLUENT and

EFFLUENT of all the 3 STP’s

X- Axis: Influent and Effluent

Y- Axis: Concentration in mg/L, for all parameters except pH and Temp (C)

Fig 4.1: Graphical Representation of pH

Fig 4.2: Graphical Representation of Temp

Effluent

Mohali STP (MBBRTechnology)

pH

Effluent

Mohali STP (MBBRTechnology)

Temp

59

Fig 4.3: Graphical Representation of TSS

Fig 4.4: Graphical Representation of TDS

0

20

40

60

80

100

120

140

160

180

200

Influent

Raipur Kalan STP(UASB Technology)

0

50

100

150

200

250

300

Influent

Raipur Kalan STP(UASB Technology)

TSS

Conc

entr

atio

nin

mg/

LTD

SCo

ncen

trat

ion

inm

g/L

59

Fig 4.3: Graphical Representation of TSS

Fig 4.4: Graphical Representation of TDS

Influent Effluent Influent Effluent Influent Effluent

Raipur Kalan STP(UASB Technology)

Raipur Khurd STP(ASP Technology)

Mohali STP (MBBRTechnology)

Influent Effluent Influent Effluent Influent Effluent

Raipur Kalan STP(UASB Technology)

Raipur Khurd STP(ASP Technology)

Mohali STP (MBBRTechnology)

TSS

Conc

entr

atio

nin

mg/

LTD

SCo

ncen

trat

ion

inm

g/L

59

Fig 4.3: Graphical Representation of TSS

Fig 4.4: Graphical Representation of TDS

Effluent

Mohali STP (MBBRTechnology)

TSS

TDS

TSS

Conc

entr

atio

nin

mg/

LTD

SCo

ncen

trat

ion

inm

g/L

60

Fig 4.5: Graphical Representation of Oil and Grease

Fig 4.6: Graphical Representation of BOD

00.5

11.5

22.5

33.5

44.5

5

Influent

Raipur Kalan STP(UASB

Technology)

020406080

100120140160180200

Influent

Raipur Kalan STP(UASB Technology)

BOD

Conc

entr

atio

n in

mg/

LO

il an

d Gr

ease

Conc

entr

atio

nin

mg/

L

60

Fig 4.5: Graphical Representation of Oil and Grease

Fig 4.6: Graphical Representation of BOD

Influent Effluent Influent Effluent Influent Effluent

Raipur Kalan STP(UASB

Technology)

Raipur Khurd STP(ASP Technology)

Mohali STP(MBBR

Technology)

Oil and grease

Influent Effluent Influent Effluent Influent Effluent

Raipur Kalan STP(UASB Technology)

Raipur Khurd STP(ASP Technology)

Mohali STP (MBBRTechnology)

BOD3, 27 °C

BOD

Conc

entr

atio

n in

mg/

LO

il an

d Gr

ease

Conc

entr

atio

nin

mg/

L

60

Fig 4.5: Graphical Representation of Oil and Grease

Fig 4.6: Graphical Representation of BOD

Oil and grease

BOD3, 27 °C

BOD

Conc

entr

atio

n in

mg/

LO

il an

d Gr

ease

Conc

entr

atio

nin

mg/

L

61

Fig 4.7: Graphical Representation of COD

Fig 4.8: Graphical Representation of Cl-

0

50

100

150

200

250

300

350

400

Influent

Raipur Kalan STP(UASB Technology)

0

20

40

60

80

100

120

140

160

180

200

Influent Effluent

Raipur Kalan STP(UASB

Technology)

CI-

Conc

entr

atio

nin

mg/

LCO

DCo

ncen

trat

ion

inm

g/L

61

Fig 4.7: Graphical Representation of COD

Fig 4.8: Graphical Representation of Cl-

Influent Effluent Influent Effluent Influent Effluent

Raipur Kalan STP(UASB Technology)

Raipur Khurd STP(ASP Technology)

Mohali STP (MBBRTechnology)

Influent Effluent Influent Effluent Influent Effluent

Raipur Kalan STP(UASB

Technology)

Raipur KhurdSTP (ASP

Technology)

Mohali STP(MBBR

Technology)

Cl-

CI-

Conc

entr

atio

nin

mg/

LCO

DCo

ncen

trat

ion

inm

g/L

61

Fig 4.7: Graphical Representation of COD

Fig 4.8: Graphical Representation of Cl-

Effluent

Mohali STP (MBBRTechnology)

COD

CI-

Conc

entr

atio

nin

mg/

LCO

DCo

ncen

trat

ion

inm

g/L

62

Fig 4.9: Graphical Representation of NO3 –N

Fig 4.10: Graphical Representation of NH3 –N

00.5

11.5

22.5

33.5

44.5

5

Influent

Raipur Kalan STP(UASB Technology)

0

5

10

15

20

25

30

35

Influ

ent

Raipur KalanSTP (UASB

Technology)

NO

3–N

Conc

entr

atio

nin

mg/

LN

H 3–

NCo

ncen

trat

ion

inm

g/L

62

Fig 4.9: Graphical Representation of NO3 –N

Fig 4.10: Graphical Representation of NH3 –N

Influent Effluent Influent Effluent Influent Effluent

Raipur Kalan STP(UASB Technology)

Raipur Khurd STP(ASP Technology)

Mohali STP (MBBRTechnology)

Efflu

ent

Influ

ent

Efflu

ent

Influ

ent

Efflu

ent

Raipur KalanSTP (UASB

Technology)

Raipur KhurdSTP (ASP

Technology)

Mohali STP(MBBR

Technology)

NH3 –N

NO

3–N

Conc

entr

atio

nin

mg/

LN

H 3–

NCo

ncen

trat

ion

inm

g/L

62

Fig 4.9: Graphical Representation of NO3 –N

Fig 4.10: Graphical Representation of NH3 –N

NO3 -N

NO

3–N

Conc

entr

atio

nin

mg/

LN

H 3–

NCo

ncen

trat

ion

inm

g/L

63

Fig 4.11: Graphical Representation of PO4-

Table 4.5: Comparison of all the three STP’s Effluent with Central Pollution

Control Board (CPCB), General Standards for the Discharge of Environmental

Pollutants according to The Environment (Protection) Rules, 1986 Schedule-VI

Part –A: Effluents

Parameter

Raipur Kalan

STP (UASB)

Technology

Average

Effluent

Raipur

Khurd STP

(ASP)

Technology

Average

Effluent

Mohali STP

(MBBR)

Technology

Average

Effluent

Comparison Result

With CPCB

Effluent Discharge

Standards into

Inland Surface

Water

pH 8.2 8.3 8.0Lower than

Permissible Limit

0

2

4

6

8

10

12

14

16

18

20

Influent

Raipur Kalan STP(UASB Technology)

PO4

-Co

ncen

trat

ion

inm

g/L

63

Fig 4.11: Graphical Representation of PO4-

Table 4.5: Comparison of all the three STP’s Effluent with Central Pollution

Control Board (CPCB), General Standards for the Discharge of Environmental

Pollutants according to The Environment (Protection) Rules, 1986 Schedule-VI

Part –A: Effluents

Parameter

Raipur Kalan

STP (UASB)

Technology

Average

Effluent

Raipur

Khurd STP

(ASP)

Technology

Average

Effluent

Mohali STP

(MBBR)

Technology

Average

Effluent

Comparison Result

With CPCB

Effluent Discharge

Standards into

Inland Surface

Water

pH 8.2 8.3 8.0Lower than

Permissible Limit

Influent Effluent Influent Effluent Influent Effluent

Raipur Kalan STP(UASB Technology)

Raipur Khurd STP (ASPTechnology)

Mohali STP (MBBRTechnology)

PO4

-Co

ncen

trat

ion

inm

g/L

63

Fig 4.11: Graphical Representation of PO4-

Table 4.5: Comparison of all the three STP’s Effluent with Central Pollution

Control Board (CPCB), General Standards for the Discharge of Environmental

Pollutants according to The Environment (Protection) Rules, 1986 Schedule-VI

Part –A: Effluents

Parameter

Raipur Kalan

STP (UASB)

Technology

Average

Effluent

Raipur

Khurd STP

(ASP)

Technology

Average

Effluent

Mohali STP

(MBBR)

Technology

Average

Effluent

Comparison Result

With CPCB

Effluent Discharge

Standards into

Inland Surface

Water

pH 8.2 8.3 8.0Lower than

Permissible Limit

Effluent

Mohali STP (MBBRTechnology)

PO4-

PO4

-Co

ncen

trat

ion

inm

g/L

64

Temp 22.8 22.5 22.1Lower than

Permissible Limit

TSS 32.3 89.6 33.6Lower than

Permissible Limit

TDS 163.3 146.0 125.6Lower than

Permissible Limit

Oil and

Grease0.4 0.6 0.5

Lower than

Permissible Limit

BOD3, 27 C 33.6 38.3 23.3

Higher than

Permissible Limit for

Raipur Kalan STP

and Raipur Khurd

STP

COD 148.3 83.0 67.6Lower than

Permissible Limit

Cl- 66.0 70.0 139.3Lower than

Permissible Limit

NO3 -N 1.9 1.7 1.6Lower than

Permissible Limit

NH3 –N 32.3 31.8 21.9Lower than

Permissible Limit

PO4-

4.8 5.0 2.1

Lower than

Permissible Limit for

Raipur Kalan STP

and Mohali STP but

Exactly upto

Permissible Limit for

Raipur Khurd STP

65

Fig 4.12: Graphical Representation of Parameter BOD Exceeding

CPCB Standard

For evaluating overall Performance/Efficiency of an STP four major

parameters are considered which are TSS, TDS, COD and BOD

Removal / Reduction Efficiency is Calculated as:

Initial Amount – Reduced Amount

0

5

10

15

20

25

30

35

40

45

(UASB) Technology

Raipur Kalan STP

Initial AmountX 100Er =

BOD

Conc

entr

atio

nin

mg/

L

StandardValue

65

Fig 4.12: Graphical Representation of Parameter BOD Exceeding

CPCB Standard

For evaluating overall Performance/Efficiency of an STP four major

parameters are considered which are TSS, TDS, COD and BOD

Removal / Reduction Efficiency is Calculated as:

Initial Amount – Reduced Amount

(UASB) Technology (ASP) Technology (MBBR) Technology

Raipur Kalan STP Raipur Khurd STP Mohali STP

Initial AmountX 100Er =

BOD

Conc

entr

atio

nin

mg/

L

StandardValue

65

Fig 4.12: Graphical Representation of Parameter BOD Exceeding

CPCB Standard

For evaluating overall Performance/Efficiency of an STP four major

parameters are considered which are TSS, TDS, COD and BOD

Removal / Reduction Efficiency is Calculated as:

Initial Amount – Reduced Amount

(MBBR) Technology

BOD

Initial AmountX 100Er =

BOD

Conc

entr

atio

nin

mg/

L

StandardValue

66

Table 4.6: Overall Performance or Removal/Reduction Efficiency of all the 3

STP’s

Removal/Reduction

EfficiencyTSS TDS COD BOD3, 27 C

Raipur Kalan STP

(UASB) Technology76 % 39 % 56 % 79 %

Raipur Khurd STP

(ASP) Technology51% 46 % 78% 73 %

Mohali STP

(MBBR) Technology78% 55 % 75 % 88 %

67

Fig 4.13: Graphical Representation of TSS for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Raipur Kalan STP(UASB) Technology

TSS

Rem

oval

/Red

uctio

nPe

rcen

tage

67

Fig 4.13: Graphical Representation of TSS for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

Raipur Kalan STP(UASB) Technology

Raipur Khurd STP(ASP) Technology

Mohali STP (MBBR)Technology

TSS

Rem

oval

/Red

uctio

nPe

rcen

tage

67

Fig 4.13: Graphical Representation of TSS for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

Mohali STP (MBBR)Technology

TSS

TSS

Rem

oval

/Red

uctio

nPe

rcen

tage

68

Fig 4.14: Graphical Representation of TDS for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

0%

10%

20%

30%

40%

50%

60%

Raipur Kalan STP(UASB) Technology

TDS

Rem

oval

/Red

uctio

nPe

rcen

tage

68

Fig 4.14: Graphical Representation of TDS for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

Raipur Kalan STP(UASB) Technology

Raipur Khurd STP(ASP) Technology

Mohali STP (MBBR)Technology

TDS

Rem

oval

/Red

uctio

nPe

rcen

tage

68

Fig 4.14: Graphical Representation of TDS for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

Mohali STP (MBBR)Technology

TDS

TDS

Rem

oval

/Red

uctio

nPe

rcen

tage

69

Fig 4.15: Graphical Representation of COD for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Raipur Kalan STP(UASB) Technology

COD

Rem

oval

/Red

uctio

nPe

rcen

tage

69

Fig 4.15: Graphical Representation of COD for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

Raipur Kalan STP(UASB) Technology

Raipur Khurd STP(ASP) Technology

Mohali STP (MBBR)Technology

COD

Rem

oval

/Red

uctio

nPe

rcen

tage

69

Fig 4.15: Graphical Representation of COD for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

Mohali STP (MBBR)Technology

COD

COD

Rem

oval

/Red

uctio

nPe

rcen

tage

70

Fig 4.16: Graphical Representation of BOD3, 27 C for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Raipur Kalan STP(UASB) Technology

BOD

Rem

oval

/Red

uctio

nPe

rcen

tage

70

Fig 4.16: Graphical Representation of BOD3, 27 C for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

Raipur Kalan STP(UASB) Technology

Raipur Khurd STP(ASP) Technology

Mohali STP (MBBR)Technology

BOD

Rem

oval

/Red

uctio

nPe

rcen

tage

70

Fig 4.16: Graphical Representation of BOD3, 27 C for Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

BOD3, 27 °C

BOD

Rem

oval

/Red

uctio

nPe

rcen

tage

71

Fig 4.17: Graphical Representation of Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

TSS

Rem

oval

/Red

uctio

nPe

rcen

tage

71

Fig 4.17: Graphical Representation of Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

TSS TDS COD BOD

Raipur Kalan STP (UASB)Technology

Raipur Khurd STP (ASP)Technology

Mohali STP (MBBR)Technology

Rem

oval

/Red

uctio

nPe

rcen

tage

71

Fig 4.17: Graphical Representation of Overall Performance or

Removal/Reduction Efficiency of all the 3 STP’s

Raipur Kalan STP (UASB)Technology

Raipur Khurd STP (ASP)Technology

Mohali STP (MBBR)Technology

Rem

oval

/Red

uctio

nPe

rcen

tage

72

Since out of 30 MGD of STP, Mohali 10 MGD treated waste water is reused for Irrigation purpose

in various gardens and lawns of Sector: 19, 20, 21, 29, 30, 33, 34, 36, 40, 42, 43, 44, 46, 47, 48, 51

and 52 of Chandigarh city therefore Average Effluent of this STP is compared with the CPCB

Effluent Discharge Standards into Land for Irrigation.

Table 4.7: Comparison of Mohali STP, (MBBR) Technology, Average Effluent

with the CPCB Effluent Discharge Standards into Land for Irrigation

Parameter

Mohali STP

(MBBR) Technology

Average Effluent

Comparison Result With CPCB

Effluent Discharge Standards

into Land for Irrigation

pH 8.0 Lower than Permissible Limit

Temp 22.1 _

TSS 33.6 Lower than Permissible Limit

TDS 125.6 _

Oil and Grease 0.5 Lower than Permissible Limit

BOD3, 27 C 23.3 Lower than Permissible Limit

COD 67.6 _

Cl- 139.3 _

NO3 -N 1.6 _

NH3 –N 21.9 _

PO4- 2.1 _

73

4.2 DISCUSSIONS

pH

The pH value of sewage indicates the negative log of hydrogen ion concentration present in

sewage. It is thus, an indicator of the alkalinity or acidity of sewage. If the pH value is less than 7,

the sewage is acidic, and if the pH value is more than 7, the sewage is alkaline. The

determination of pH value is important because of the fact that efficiency of certain treatment

methods depends upon the availability of a suitable pH value. The PH directly affects the

performance of a secondary treatment process because the existence of most biological life is

dependent upon the narrow and critical range of pH. Thus, pH is also an indicator of biological

life since most of them thrive in a quite narrow and critical pH range. In addition to all above,

Chemical processes used to coagulate wastewater, dewater sludge or oxidize certain substances,

such as cyanide ion requires that the pH be controlled within a narrow range. Thus, any variation

beyond acceptable range could be fatal to a particular organism.

During the course of the study it was recorded that pH varies from acidic to alkaline i.e 6.8-7.9,

6.9-8.4 and alkaline i.e 7.2-7.8 for Influent of STP Raipur Kalan, Raipur Khurd and Mohali

respectively. Maximum pH value was recorded in the month of February, March and March for

Influent of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average pH value of the

Influent was recorded as 7.5, 7.7 and 7.5 for STP Raipur Kalan, Raipur Khurd and Mohali

respectively indicating that the Influent was alkaline in nature for all the three STP’s.

Also during the course of the study it was recorded that pH varies from 7.7-8.6, 7.7-8.9 and 7.6-8.4

for Effluent of STP Raipur Kalan, Raipur Khurd and Mohali respectively which indicates that for

all the above mentioned STP’s the Effluent during the duration of study was alkaline in nature.

Maximum pH value was recorded in the month of February, March and March for effluent of STP

Raipur Kalan, Raipur Khurd and Mohali respectively. Average pH value of the Effluent was

recorded as 8.2, 8.3 and 8.0 for STP Raipur Kalan, Raipur Khurd and Mohali respectively which

clearly shows that the Effluent from above three STP’s were alkaline in nature. Also Average pH

74

value of the Effluent for all the three STP’s were under Permissible Limit according to CPCB

Effluent Discharge Standards into Inland Surface water.

Since out of 30 MGD of STP, Mohali 10 MGD treated waste water is reused for Irrigation purpose

in various gardens and lawns of Sector: 19, 20, 21, 29, 30, 33, 34, 36, 40, 42, 43, 44, 46, 47, 48, 51

and 52 of Chandigarh city, Average Effluent value of pH recorded for this STP was also under

permissible limit according to CPCB Effluent Discharge Standards into Land for Irrigation.

Temperature (Temp)

The determination of temperature is also important because temperature has an effect on the

biological activity of bacteria present in sewage, and also it affects the solubility of gases in

sewage. In addition, temperature also affects the viscosity of sewage, which in turn affects the

sedimentation process in its treatment.

In the present study temperature varies from 18.4-26.3oC, 18.6-29.9oC and 18.3-26.1oC for Influent

of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Maximum temperature value of

influent was recorded in the month of April for all the three STP’s. Average temperature was

recorded as 23.1oC, 23.4oC and 22.7oC for Influent of STP Raipur Kalan, Raipur Khurd and

Mohali respectively. Not much variation was found in temperature of Influent for all the three

STP’s.

Also it was recorded that temperature varies from 18.1-27.4oC, 18.0-27.7oC and 17.7-26.5oC for

Effluent of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Maximum temperature

value of Effluent was recorded in the month of April for all the three STP’s. Average temperature

was recorded as 22.8oC, 22.5oC and 22.1oC for Effluent of STP Raipur Kalan, Raipur Khurd and

Mohali respectively. Not much variation was found in temperature of Effluent for all the three

STP’s.

Also Average temperature value of the Effluent for all the three STP’s were under Permissible

Limit according to CPCB Effluent Discharge Standards into Inland Surface water

75

Total Suspended Solids (TSS) and Total dissolved Solids (TDS)

Sewage normally contains very small amount of solids in relation to the huge quantity of water

(99.9%). Solids in the sewage comprise of both: Organic as well as Inorganic solids. As a general

rule, the presence of inorganic solids in sewage is not harmful. They require only mechanical

appliances for their removal in the treatment plant. On the other hand suspended and dissolved

organic solids are responsible for creating nuisance, if disposed of untreated.

Total Solids (TS) have great implications in the control of biological and physical waste water

treatment processes. Total solids (TS), is a sum of two terms namely Total Suspended Solids

(TSS) and Total Dissolved Solids (TDS). TDS and TSS are common indicators of polluted water

and wastewater therefore these to parameters are must to determine. Also in overall performance

of an STP they are considered as important parameters. More over TDS of the wastewater is of

concern as it affects the reuse of wastewater for agricultural purposes, by decreasing the hydraulic

conductivity of irrigated land.

TSS

In the present study it was recorded that TSS varies from 126-159 mg/L, 141-238 mg/L and 149-

172 mg/L for the Influent of STP Raipur Kalan, Raipur Khurd and Mohali respectively.

Maximum TSS value was recorded in the month of February, March and February for Influent of

STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average TSS value of the Influent was

recorded as 139.6 mg/L, 182.3 mg/L and 157.0 mg/L for STP Raipur Kalan, Raipur Khurd and

Mohali respectively. Average TSS value for the Influent of all the three STP’s indicated much

variation among the three STP’s in terms of TSS value for the Influent, which is attributed to

large difference in the organic and inorganic loading of solids with liquid content in all the three

STP’s.

In the present study it was recorded that TSS varies from 29-38 mg/L, 51-155 mg/L and 30-39

mg/L for the Effluent of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Maximum

TSS value was recorded in the month of February, March and March for Effluent of STP Raipur

Kalan, Raipur Khurd and Mohali respectively.

76

Average TSS value of the Effluent was recorded as 32.3 mg/L, 89.6 mg/L and 157.0 mg/L for

STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average TSS value for the Effluent of

all the three STP’s indicated much variation among the three STP’s in terms of TSS value for the

Effluent, which is again attributed to large difference in the organic and inorganic loading of

solids with liquid content in all the three STP’s.

Also Average TSS value of the Effluent for all the three STP’s were under Permissible Limit

according to CPCB Effluent Discharge Standards into Inland Surface water.

Since out of 30 MGD of STP, Mohali 10 MGD treated waste water is reused for Irrigation purpose

in various gardens and lawns of Sector: 19, 20, 21, 29, 30, 33, 34, 36, 40, 42, 43, 44, 46, 47, 48,

51 and 52 of Chandigarh city, Average Effluent value of TSS value recorded for this STP was also

under permissible limit according to CPCB Effluent Discharge Standards into Land for Irrigation.

TDS

In the present study it was recorded that TDS varies from 237-292 mg/L, 229-312 mg/L and 254-

299 mg/L for the Influent of STP Raipur Kalan, Raipur Khurd and Mohali respectively.

Maximum TDS value of Influent was recorded in the month of March for all the three STP’s.

Average TDS value of the Influent was recorded as 270.6 mg/L, 275.3 mg/L and 281.3mg/L for

STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average TDS value for the Influent

of all the three STP’s indicated not much variation among the three STP’s in terms of TDS value

for the Influent, which is attributed to less difference in the organic and inorganic loading of

solids with liquid content in all the three STP’s.

In the present study it was recorded that TDS varies from 157-173 mg/L, 122-169 mg/L and 106-

140 mg/L for the Effluent of STP Raipur Kalan, Raipur Khurd and Mohali respectively.

Maximum TDS value was recorded in the month of March, February and March for Effluent of

STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average TDS value of the Effluent

was recorded as 163.3 mg/L, 146.0 mg/L and 125.6 mg/L for STP Raipur Kalan, Raipur Khurd

and Mohali respectively. Average TDS value for the Effluent of all the three STP’s indicated

much variation among the three STP’s in terms of TDS value for the Effluent, which is again

77

attributed to large difference in the organic and inorganic loading of solids with liquid content in

all the three STP’s. Also Average TDS value of the Effluent for all the three STP’s were under

Permissible Limit according to CPCB Effluent Discharge Standards into Inland Surface water.

Oil and grease

Oil and Grease are derived in sewage from the discharges of animals and vegetable matter, which

mainly come from kitchens, hotels and restaurants and many other places. The determination of

Oil and Grease in sewage is important because such matter forms scum on the top of the

sedimentation tanks and clogs the voids of the filtering media. They thus interfere with the normal

treatment methods, and hence need proper detection and removal.

In the present investigation it was recorded that Oil and Grease varies from 2.4-3.7 mg/L, 3.6-4.5

mg/L and 3.3-5.2 mg/L for the Influent of STP Raipur Kalan, Raipur Khurd and Mohali

respectively. Also was recorded that Oil and Grease varies from 0.2-0.6 mg/L, 0.3-0.9 mg/L and

0.2-0.9 mg/L for the Effluent of STP Raipur Kalan, Raipur Khurd and Mohali respectively.

Not much variation was observed in Influent and Effluent value of Oil and Grease for all the three

STP’s which shows that the discharge from the various sources of Oil and Grease contain less

amount of oily and greasy material during the duration of study.

Also Average Oil and Grease value of the Effluent for all the three STP’s were under Permissible

Limit according to CPCB Effluent Discharge Standards into Inland Surface water.

Since out of 30 MGD of STP, Mohali 10 MGD treated waste water is reused for Irrigation purpose

in various gardens and lawns of Sector: 19, 20, 21, 29, 30, 33, 34, 36, 40, 42, 43, 44, 46, 47, 48, 51

and 52 of Chandigarh city, Average Effluent value of Oil and Grease recorded for this STP was

also under permissible limit according to CPCB Effluent Discharge Standards into Land for

Irrigation.

78

Biochemical Oxygen Demand (BOD)

Biochemical Oxygen Demand (BOD) is the measure of biodegradable organic matter present in a

water sample and can be defined as the amount of oxygen required by the microbes in stabilizing

the biologically degradable organic matter under aerobic condition. Determination of BOD is

considered very important because BOD value can be used as a measure of waste strength in terms

of oxygen required. The quantity of oxygen required may be taken as a measure of its content of

decomposable organic matter. The rate of BOD exertion is governed by the characteristics of

sewage, its decomposable organic matter, bacterial population and temperature. Moreover BOD is

the most essential parameter which is considered to define the overall performance or efficiency of

an STP.

During the study it was recorded that BOD varies from 154-169 mg/L, 140-151 mg/L and 184-189

mg/L for the Influent of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Maximum

BOD value of Influent was recorded in the month of April, March and April for Influent of STP

Raipur Kalan, Raipur Khurd and Mohali respectively. The highest value of BOD for Influent of the

above three STP’s noticed clearly indicates that this highest value is attributed to heavy organic

and inorganic loading with less amount of water in the above mentioned months. Average BOD

was recorded as 166.3 mg/L, 146.6 3 mg/L and 186.6 3 mg/L for the Influent of STP Raipur

Kalan, Raipur Khurd and Mohali respectively, high average value of BOD for all the three STP’s

indicates the degree of pollution of Influent in each STP. Also DO was very less at inlet for all

three STP’s which is further stimulated by oxidation of sewage ammonia to nitrates, septic

condition and heavy organic loadings, therefore high BOD value are obtained at inlet in all the

three STP’s . Out of all the three STP’s mentioned above the average BOD value was maximum in

Mohali STP

BOD value for Effluent was in the range of 32-35 mg/L, 31-47 mg/L and 17-27 mg/L of STP

Raipur Kalan, Raipur Khurd and Mohali respectively. Average BOD value for Effluent recorded

was 33.6 mg/L, 38.3 mg/L and 23.3 mg/L of STP Raipur Kalan, Raipur Khurd and Mohali

respectively.

It was observed that average BOD value for Effluent of STP Raipur Kalan and Raipur Khurd was

not under permissible limit according to CPCB Effluent Discharge Standards into Inland Surface

79

water. But average BOD value for Effluent of STP Mohali was under permissible limit according

to CPCB Effluent Discharge Standards into Inland Surface water.

Since out of 30 MGD of STP, Mohali 10 MGD treated waste water is reused for Irrigation purpose

in various gardens and lawns of Sector: 19, 20, 21, 29, 30, 33, 34, 36, 40, 42, 43, 44, 46, 47, 48, 51

and 52 of Chandigarh city, Average Effluent value of BOD recorded for this STP was also under

permissible limit according to CPCB Effluent Discharge Standards into Land for Irrigation.

Chemical Oxygen Demand (COD)

Chemical Oxygen Demand (COD) is a measure of oxygen equivalent to the organic matter content

of the water susceptible to oxidation by a strong chemical oxidant and thus is an index of organic

pollution in the river. The test measures the amount of oxygen required for chemical oxidation of

organic matter in the sample to carbon dioxide and water. COD is also an important parameter of

water indicating the health scenario of freshwater bodies.

COD determination is considered important because it is widely used for measuring the pollution

strength of wastewater. All organic compounds except few exceptions can be oxidized to carbon

dioxide and water by the action of strong oxidizing agents regardless of biological assimilability of

substances.

In the present study COD value varies from 299-367 mg/L, 358-395 mg/L and 312-371 mg/L for

the Influent of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Maximum COD value of

Influent was recorded in the month of February for Influent of all the three STP’s. Highest value

of COD in the month of February was due to the heavy organic loading with less amount of water.

Average Influent value of COD recorded was 338.3 mg/L, 377.3 mg/L and 346.6 mg/L for the

Influent of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Not much variation was

found in COD value for the Influent of STP Raipur Kalan, Raipur Khurd and Mohali.

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COD value recorded in the range of 105-196 mg/L, 72-99 mg/L and 56-84 mg/L for the Effluent of

STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average COD value was recorded as

148.3 mg/L, 83 mg/L and 67.6 mg/L for the Effluent of STP Raipur Kalan, Raipur Khurd and

Mohali respectively.

It has been observed that average COD value for Effluent of STP Raipur Kalan, Raipur Khurd and

Mohali was under permissible limit according to CPCB Effluent Discharge Standards into Inland

Surface water.

Chloride (Cl-)

Chlorides are generally found in municipal sewage, and are derived from human feces and urinary

discharges etc. Determination of Cl- is important because Cl- is one of the major inorganic anions

in water and wastewater. Chloride is not strictly a pollutant but high concentration may harm

agriculture crops and corrode the metallic pipes.

However, large amounts of chloride content may enter from industries like ice cream plants, meat

salting, etc thus increasing the chloride contents of sewage. Hence, when the chloride content of a

given sewage is found to be high, it indicates the presence of industrial wastes or infiltration of sea

water, thereby indicating the strength of sewage.

In the present study Cl- value varies from 169-192 mg/L, 11-147 mg/L and 158-174mg/L for the

Influent of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average Influent value of

Cl- recorded was 180.6 mg/L, 125.3 mg/L and 166.6 mg/L for the Influent of STP Raipur Kalan,

Raipur Khurd and Mohali respectively. Not much variation was found in Cl- value for the Influent

of STP Raipur Kalan, Raipur Khurd and Mohali which indicates that there is no presence of

industrial waste or infiltration of sea water which generally attributes to the strength of sewage.

Cl- value recorded in the range of 53-88 mg/L, 33-98 mg/L and 106-199 mg/L for the Effluent of

STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average Cl- value was recorded as 66.0

mg/L, 70.0 mg/L and 139.3 mg/L for the Effluent of STP Raipur Kalan, Raipur Khurd and Mohali

respectively. Average Cl- value of Effluent for the three STP’s indicates much variation among the

three with respect to the chloride content.

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It was observed that average Cl- value for Effluent of STP Raipur Kalan, Raipur Khurd and Mohali

was under permissible limit according to CPCB Effluent Discharge Standards into Inland Surface

water.

Nutrient Load

The presence of nitrogen in sewage indicates the presence of organic matter, and may occur in one

or more of the following forms: Free ammonia, Ammonical nitrogen, Nitrites and Nitrates. Source

of nitrogenous organic matter for sewage are mainly animal and human waste. Ammonical

nitrogen (NH3 –N) indicates quantity of nitrogen present in sewage before the decomposition of

organic matter is started. Nitrates indicates the presence of fully oxidized organic matter in sewage.

Therefore the determination of Ammonical nitrogen (NH3 –N) and Nitrate nitrogen (NO3 –N) are

important in sewage.

Ammonical nitrogen (NH3 –N)

NH3 –N in the present study varies from 19.5-29.7 mg/L, 23.2-34.8 mg/L and 17.5-21.6 mg/L for

the Influent of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average Influent value

of NH3 –N recorded was 25.9 mg/L, 27.7 mg/L and 19.6 mg/L for the Influent of STP Raipur

Kalan, Raipur Khurd and Mohali respectively indicating little bit variation in NH3 –N Influent for

the above three STP’s.

Effluent value for NH3 –N was recorded in the range of 28.8-38.3 mg/L, 28.1-3.8 mg/L and 17.6-

24.5 mg/L for STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average Effluent value

for NH3 –N recorded was 25.9 mg/L, 27.7 mg/L and 19.6 mg/L of STP Raipur Kalan, Raipur

Khurd and Mohali respectively. Effluent value of increases than the influent value in all the

months during the duration of study of STP Raipur Kalan, indicating that nitrogenous organic

matter is decomposed properly and and NH3 is evolved as an end product. Moreover Average

Effluent value for NH3 –N of all the three STP’s was under permissible limit according to CPCB

Effluent Discharge Standards into Inland Surface water.

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Nitrate nitrogen (NO3 –N)

Nitrate is made in the human body, the rate of production being influenced by factors such as

exercise. Therefore presence of nitrates in the wastewater is one of the indicators of contact with

human wastes.

NO3 –N value was recorded in the range of 1.7-4.7 mg/L, 2.4-5.9 mg/L and 3.3-5.2 mg/L for the

Influent of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average Influent value of

NO3 –N recorded was 3.1 mg/L, 4.1 mg/L and 4.4 mg/L for the Influent of STP Raipur Kalan,

Raipur Khurd and Mohali respectively indicating that NO3 –N content in the inlet of all the three

STP’s were almost the same as same amount of nitrogenous organic matter entered in all the above

three STP’s.

In the present study it was recorded that Effluent value for NO3 –N varies from 1.3-3.2 mg/L, 1.4-

2.3 mg/L and 1.2-2.4 mg/L for the Effluent of STP Raipur Kalan, Raipur Khurd and Mohali

respectively. Average Effluent value for NO3 –N recorded was 1.9 mg/L, 1.7 mg/L and 1.6 mg/L

of STP Raipur Kalan, Raipur Khurd and Mohali respectively indicating that NO3 –N content in the

outlet of all the three STP’s were almost the same. Moreover Average Effluent value for NO3 –N

of all the three STP’s was under permissible limit according to CPCB Effluent Discharge

Standards into Inland Surface water.

Phosphate (PO4- )

Phosphorous occurs in wastewater as phosphates. The source of phosphates to sewage are mainly

due to detergents, they are added during laundering or other cleaning, because these materials are

major constituents of many commercial cleaning preparations. Organic phosphates are formed

primarily by biological processes. They are contributed to sewage by body wastes and food

residues, and may be formed from orthophosphates in the biological treatment processes or by

receiving water biota. Phosphates also occur in bottom sediments and biological sludge, both as

precipitated inorganic forms and incorporated into organic compounds.

PO4- value varies from 11.6-14.9 mg/L, 15.2-20.2 mg/L and 13.5-24.8 mg/L for the Influent of

STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average Influent value of PO4-

recorded was 15.3 mg/L, 17.5 mg/L and 18.1 mg/L of STP Raipur Kalan, Raipur Khurd and

83

Mohali respectively indicating that phosphates content entering the inlet of all the above three

STP’s was near about the same.

In the present study PO4- value varies from 3.8-5.5 mg/L, 3.9-7.8 mg/L and 1.4-2.9 mg/L for the

Effluent of STP Raipur Kalan, Raipur Khurd and Mohali respectively. Average Effluent value of

PO4- recorded was 15.3 mg/L, 17.5 mg/L and 18.1 mg/L of STP Raipur Kalan, Raipur Khurd and

Mohali respectively. Average Effluent value of PO4- recorded was 4.8 mg/L, 5.0 mg/L and 2.1

mg/L of STP Raipur Kalan, Raipur Khurd and Mohali respectively.

Moreover Average Effluent value for PO4- of STP Raipur Kalan and Mohali was under permissible

limit according to CPCB Effluent Discharge Standards into Inland Surface water, but Average

Effluent value for PO4- of STP Raipur Khurd was exactly upto permissible limit according to

CPCB Effluent Discharge Standards into Inland Surface water.

Determination of all the above the three nutrients were important also from the point of view that

there increased concentration in effluent may cause eutrophication of river Ghaghar, in which the

effluent of all the above three STP’s is disposed of. Hence proper concentration of all the above

three nutrients should be maintained before discharging the sewage effluent into the water body.

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CHAPTER 5

CONCLUSIONS AND RECOMMENDATIONS

5.1 CONCLUSIONS

From the study conducted for the comparison of 3 STP’s in the vicinity of Chandigarh city

following conclusions are made:

Physico-Chemical and Biological Parameters evaluated for STP Mohali was under

permissible limit according to CPCB Effluent Discharge Standards into Inland Surface

Water during the course of study.

Since out of 30 MGD of STP, Mohali 10 MGD treated waste water is reused for Irrigation

purpose in various gardens and lawns of Sector: 19, 20, 21, 29, 30, 33, 34, 36, 40, 42, 43,

44, 46, 47, 48, 51 and 52 of Chandigarh city therefore after evaluating various Physico-

Chemical and Biological Parameters for this STP it was revealed that all the parameters

evaluated were under permissible limit according to CPCB Effluent Discharge Standards

into Land for Irrigation during the course of study. Hence Effluent from this STP is safer for

agricultural use.

BOD value of the Effluent of STP Raipur Kalan and Raipur Khurd was not under

permissible limit during the course of study and Average Phosphate value of Raipur Khurd

was exactly upto permissible limit during the duration of study according to Central

Pollution Control Board (CPCB) General Standards for the Discharge of Environmental

Pollutants Part –A: Effluents, into Inland Surface Water according to The Environment

(Protection) Rules, 1986 Schedule-VI.

Also it was revealed from the performance study that efficiency of the three STP’s

mentioned above was poor with respect to removal of TDS (Total Dissolved Solids) in

contrast to the removal /reduction efficiency in other parameters like TSS (Total Suspended

Solids), BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand).

85

The order of removal/reduction efficiency was 1.TDS(39%) 2.COD(56%) 3.TSS(76%)

4.BOD(79%), 1.TDS(46%) 2.TSS(51%) 3.BOD(73%) 4.COD(78%) and 1.TDS(55%)

2.COD(75%) 3.TSS(78%) 4.BOD(88%) respectively in Raipur Kalan STP, Raipur Khurd

STP and “Diggian” Mohali STP.

In comparison with each other, out of the three STP’s, “Diggian” STP Located at Mohali

showed better results for the effluent, its removal /reduction efficiency for BOD is 88% and

is highest among Raipur Kalan STP and Raipur Khurd STP which is 79% and 73%

respectively. The greater removal /reduction efficiency for STP Mohali is attributed to the

chemical treatment employed at this STP in the form of Tertiary Treatment of sewage.

From the evaluation it is further concluded that Mohali STP based upon MBBR technology

have more stable results than Raipur Kalan STP, based upon UASB technology and Raipur

Khurd STP, based upon ASP technology.

The order of overall performance for the technologies studied in different STP’s are:

1.MBBR 2.UASB 3.ASP which proves that MBBR technology is ahead to UASB and

ASP technology in the treatment of sewage

5.2 RECOMMENDATIONS

MBBR technology is recommended over ASP and UASB technology because of the

following reasons (Advantages of MBBR technology over ASP and UASB technology):

It has established itself as a well proven, robust and compact reactor for the wastewater

treatment.

The efficiency of the reactor has been demonstrated in many process combination, both

for BOD removal and nutrient removal.

It can be used for small as well as large plants. The primary advantage of the process as

compared to ASP technology is its compactness and no need for sludge recirculation.

The advantages over other biofilm processes, is its flexibility, one can use almost any

reactor shape and one can choose different operating loads in a reactor volume, simply

86

by choice of carrier filling. This technology can also be used for industrial waste water,

particularly in the food industry and paper and pulp industry.

UASB technology is recommended over ASP technology because of the following reasons:

It is simple and offer reasonable performance at presumably low cost of operation and

maintenance.

No electrical energy and mechanical equipments are required in UASB.

It does not require any external aeration and thus the cost associated with energy and

devices required for aeration and their maintenance are cut to zero.

Excess sludge production from this system is negligible compared to ASP, again

significantly reducing the cost for sludge handling as treatment as treatment and

disposal of sewage sludge is technically cumbersome and economically a heavy

burden.

The UASB technology can be cost effective and viable option for the treatment of

municipal sewage over ASP, especially for low-income countries.

Final Recommendation for treatment of sewage:

1. MBBR Technology

2. UASB Technology

3. ASP Technology

5.3 Future Scope of Work

Future Scope for UASB Technology:

The system helps to lower only two parameters of wastewater which are BOD and

Suspended Solids (SS). Eventually, the system does not help in the removal of toxic

pollutants, like heavy metals, which may present in some of the wastewater. The

UASB system will therefore have to be supported by subsidiary disposal systems to

remove the toxic pollutants, if present in the wastewater.

87

Like all other anaerobic high rate systems, UASB reactors also require larger quantity

of organic matter as compared to the aerobic reactors, because the growth of aerobic

bacteria per unit of organic matter is about 10-20 times the growth of anaerobes. In

order to support microbial growth and metabolism in UASB systems, therefore, 20 to

30 times more of organic matter has to be metabolized, as compared to that in Aerobic

systems. For the success of UASB, it therefore becomes necessary to ensure the

presence of at least 10% of suspended solids in the wastewater.

Future Scope for ASP Technology:

The treatment systems must be properly operated and maintained, source of raw

sewage need to be identified, and existing facilities should be upgraded accordingly.

As for proper operation and maintenance, there is a need for trained and experienced

workers to analyze the treatment performance at defined time interval and also the

handle the machinery properly.

STP should be utilized to full capacity so as to control the quality of final effluent.

Bulking of sludge is a common trouble which has to be controlled, especially when

industrial wastewater with high carbohydrate content or antiseptic properties are

present.

The quantity of returned sludge has to be adjusted every time, as and when there is a

change in the quantity of sewage flow for the proper efficiency of the plant.

Future Scope for MBBR Technology:

The most important recommendation for MBBR technology is that Design criteria

should be well established for its proper functioning.

Since energy production is not there in MBBR technology hence measures should

be taken to enhance the production of energy in these technologies.

88

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