TREATMENT OF TRACES OF OIL FROM ELECTROPLATING INDUSTRY

WASTEWATER BY USING MEMBRANE BIOREACTOR

MOHAMED GHENGESH

Universiti Teknologi Malaysia

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TREATMENT OF TRACES OF OIL FROM ELECTROPLATING INDUSTRY

WASTEWATER BY USING MEMBRANE BIOREACTOR

MOHAMED GHENGESH

A thesis submitted in partial fulfillment of the requirements for the award

of the degree of Master of Engineering (Chemical)

Faculty of Chemical Engineering

Universiti Teknologi Malaysia

January, 2011

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Specially dedicated to my beloved father, Khalifa Ghenghesh , my beloved mother, Pauline Ghenghesh

and those who have guided and inspired me throughout my journey of education

Thanks for your love

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ACKNOWLEDGEMENT

In the name of Allah, Most Gracious, Most Merciful

All praises and thanks are first due to Almighty Allah for giving me the opportunity to

complete this work.

First and foremost, I would like to express my sincere thanks to my thesis supervisor

Assoc. Prof. Dr Mohd Ariffin bin Abu Hassan for his inspiration, suggestions, valuable

comments and encouragement thought the period of my research.

I would like to thank all Faculty members and staff at Chemical Engineering

Department. Overall thanks go to technicians of Pollution Control Laboratory, Pn.

Noraidah and En Azri, who have contributed to the successful completion of this project.

I would like to be grateful to Mr. Adhi Yuniarto of IPASA Institute for his personal

initiatives to solve different problems related to my experiments.

Finally, I am grateful to my parents and all family members for their prayers, mental

support, inspiration and sacrifice which helped me to complete this research work.

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ABSTRACT

Membrane bioreactor (MBR) is a modification of an activated sludge process

and is considered as a novel technology for treating wastewater. MBR process combines

the activated sludge process with membrane filtration, which allows for a high effluent

quality in terms of removal efficiency of oil and grease (O&G) and chemical oxygen

demand (COD). In this study, performance of a laboratory-scale submerged hollow fibre

membrane to treat oily wastewater from an electroplating plant in Johor was

investigated. The degradation of raw oily wastewater at a hydraulic retention time

(HRT) of 12.7 hours was studied. The experimental work was divided into three runs;

the sludge retention time was one week prior to each run. Results of the three runs

showed that O&G was biodegraded in the MBR treatment system with high extent, with

removal efficiency between 91.1 to 98.7%. Results also showed a high removal

efficiency of COD and BOD. The removal efficiency was 97.8% to 99.1% for COD and

77.8% to 86.1% for BOD. During the three runs membrane separation played an

important role in providing a stable and excellent final effluent quality. The higher

mixed liquor suspended solids (MLSS) concentration in Run 3 lead to higher

biodegradability of O&G and COD in the biological tank, as a result the removal

efficiency for this run was higher then for Runs 1 and 2, with a removal efficiency of

98.7% and 99.1% for O&G and COD respectively.

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ABSTRAK

Bioreaktor membran (MBR) adalah modifikasi proses lumpur teraktif yang

dipertimbangkan sebagai teknologi unggul untuk merawat sisa air buangan. Proses MBR

menggabungkan proses lumpur teraktif dengan penurasan bermembran, menjamin sisa

air buangan yang berkualiti tinggi selepas rawatan, dari segi kecekapan pengurangan

minyak dan gris dan juga pengurangan kepade keperluan oksigan terkimia (COD).

Dalam kajian ini, kecekapan membran jenis fiber berongga dalam yang ditenggelamkan

dengan skala makmal, telah digunakan untuk merawat air buangan daripada industri

pengelektrosaduran di Johor telah dikaji. Pengurangan minyak dalam air buangan pada

masa penahanan hidraulik 12.7 jam telah dikaji. Eksperimen ini telah dibahagikan

kepada 3 tahap ujikaji; dan masa penahanan lumpur adalah seminggu sebelum setiap

ujikaji. Keputusan daripada 3 ujikaji menunjukkan pengurangan kepekatan minyak dan

gris dalam rawatan system MBR dengan sempurna, dengan kecekapan perpindahan dari

91.1 kepada 98.7%. Keputusan juga menunjukkan kecekapan yang tinggi dalam

pengurangan COD dan BOD. Kecekapan perpindahan adalah dari 97.8% kepada 99.1%

untuk COD dan, dari 77.8% kepada 86.1% untuk BOD. Pemisahan membran pada

ketiga-tiga ujikaji memainkan peranan yang penting dalam pemberian kualiti air

buangan yang stabil dan berkualiti tinggi. Kekotoran membran telah didapati tidak

ketara dalam eksperimen MBR. Kepekatan MLSS yang tinggi dalam ujikaji ketiga

memberi tahap biodegradasi minyak dan gris dan juga COD yang lebih tinggi dalam

tangki biologi, disebabkan kecekapan perpindahan yang lebih tinggi bagi ujikaji ketiga

berbanding dengan ujikaji pertama dan kedua, kecekapan pengurangan bagi ujikaji

ketiga adalah 98.7% untuk minyak dan gris, dan 99.1% untuk COD.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

TITLE PAGE i

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF FIGURES x

LIST OF TABLES xi

LIST OF ABBERVIATIONS xii

I INTRODUCTION 1

1.1 Research Background 1

1.2 Problem Statement 4

1.3 Objective of the Study 5

1.4 Scopes of the Study 6

II LITERATURE REVIEW 7

2.1 Introduction 7

2.2 Oily Wastewater 8

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2.3 Wastewater from Electroplating Industry 10

2.4 Oil Properties 10

2.5 Treating Technology for Oily Wastewater 11

2.5.1 Primary Treatment System 12

2.5.1.1 Skimming Process 12

2.5.1.2 Gravity Separation 13

2.5.2 Secondary Treatment System 14

2.5.2.1 Chemical Treatment 14

2.5.2.2 Dissolved Air Floatation 14

2.5.2.3 Membrane Filtration 15

2.6 Bio-treatment 16

2.7 Bio-treatment Processes 16

2.8 Microbiology 18

2.9 Membrane Bioreactor 20

2.9.1 Introduction 20

2.9.2 Membrane Configurations 21

2.9.3 Membrane Types 22

2.9.3.1 Flat Sheet Module (FS) 24

2.9.3.2 Hollow Fibre (HF) 25

2.9.3.3 Tubular (MT) 25

2.10 Effluent Quality 26

2.11 Membrane Fouling 28

2.12 Critical Flux 30

2.13 Application of MBR Process for Oily 32

Wastewater Treatment

III RESEARCH METHODOLOGY 35

3.1 Materials and Microorganisms 35

3.1.1 Feed Wastewater 35

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3.1.2 Microorganisms 36

3.2 Overall Experimental Course 36

3.3 Membrane Bioreactor Set-Up 39

3.4 Operational Conditions 42

3.4.1 pH Control 43

3.4.2 Dissolved Oxygen (DO) 44

3.4.3 Transmembrane Pressure (TMP) 44

3.5 Analytical Methods 44

3.5.1 Mixed Liquor Suspended Solids 45

3.5.2 Chemical Oxygen Demand (COD) 45

3.5.3 Oil and Grease Determination (O&G) 46

3.5.4 Biochemical Oxygen Demand (BOD) 46

3.6 Sampling Frequency 46

3.7 Membrane Cleaning 47

IV RESULTS AND DISCUSSION 48

4.1 Introduction 48

4.2 Membrane Module Configuration 49

4.3 Determination of Critical Flux 50

4.4 Biomass Growth 56

4.5 Membrane Fouling 61

4.5.1 Transmembrane Pressure 61

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4.5.2 Membrane Fouling Rate and 63

Membrane Permeability

4.6 Removal Efficiency 65

4.6.1 Oil and Grease Removal Efficiency 65

4.6.2 COD Removal Efficiency 68

4.6.3 BOD Removal Efficiency 70

4.6.4 COD/BOD Ratio 72

V CONCLUSIONS AND RECOMMENDATIONS 73

5.1 Conclusions 73

5.2 Recommendations 75

REFERENCES 76

APPENDIX A1 83

APPENDIX A2 88

APPENDIX A3 93

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LIST OF FIGURES

FIGURE NO TITLE PAGE

2.1 Conventional treatment unit operation displaced 17

by MBR

2.2 Ecology of activated sludge systems 19

2.3 MBR process configurations: (a) side-stream and 22

(b) immersed

2.4 (a) Dead-end and (b) cross flow filtration 24

2.5 Flux and pressure relationship for 15 min steps 31

3.1 Overall experimental course 38

3.2 Laboratory scale MBR system schematic diagram 40

3.3a Laboratory scale MBR system to treat oily 41

wastewater

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3.3b Biological tank (main tank) 41

4.1 Membrane module configuration 49

4.2 Critical flux determination at (MLSS = 4000 mg/L) 51

4.3 Critical flux determination at (MLSS = 8000 mg/L) 52

4.4 Relationship between TMP and flux 54

4.5 Permeability and fouling rate as function of flux 55

at MLSS of 4000 mg/L

4.6 Permeability and fouling rate as function of flux 56

at MLSS of 8000 mg/L

4.7 Biomass growth for Run 1, Run 2 and Run 3 Vs 58

running time

4.8 DO and pH for Run 1 (FMNS stream) at 4 LMH 59

4.9 DO and pH for Run 2 (ONS stream) at 4 LMH 59

4.10 DO and pH for Run 3 (ONS stream) at 4 LMH 60

4.11 TMP increase for Run 1, Run 2 and Run 3 Vs 62

running time

4.12 Membrane Fouling for Run 1, Run 2 and Run 3 Vs 63

Running Time

4.13 Membrane permeability for Run 1, Run 2 and Run 3 Vs 64

running time

4.14 O&G removal efficiency for Run 1 (FMNS), at 65

MLSS of 4000 mg/L

4.15 O&G removal efficiency for Run 2 (ONS), at 66

MLSS of 4000 mg/L

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4.16 O&G removal efficiency for Run 3 (ONS), at 67

MLSS of 8000 mg/L

4.17 COD removal efficiency for Run 1 (FMNS), at 68

MLSS of 4000 mg/L

4.18 COD removal efficiency for Run 2 (ONS), at 69

MLSS of 4000 mg/L

4.19 COD removal efficiency for Run 3 (ONS), at 70

MLSS of 8000 mg/L

4.20 BOD removal efficiency for Run 1, Run 2 and Run 3 71

VS running time

4.21 COD/BOD ratio for Run 1, Run 2 and Run 3 Vs 72

running time

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LIST OF TABLE

TABLE NO TITLE PAGE

2.1 Environmental quality act 1974, industrial effluents 9

2.2 Characteristics of membrane modules 26

2.3 Performance comparison between MBR and AS systems 28

3.1 Characteristics of feed wastewater for three runs 36

3.2 Characteristics of the membrane module 39

3.3 Operating conditions for the MBR system 43

4.1 TMP gradient values for clean water and activated sludge 53

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LIST OF ABBERVIATION

AC - Activated Carbon

API - American Petroleum Institute

AS - Activated Sludge

ASP - Activated Sludge Process

BOD - Biochemical Oxygen Demand (mg/L)

COD - Chemical Oxygen Demand (mg/L)

DAF - Dissolved Air Floatation

DO - Dissolved Oxygen

DOC - Dissolved Organic Carbon

EPS - Extracellular Polymeric Substance

FMNS - Free Metals Non Solids

FS - Flat Sheet

HF - Hollow Fibre

HRT - Hydraulic Retention Time (hr)

J - Permeate Flux

MBR - Membrane Bioreactor

MF - Microfiltration

MLSS - Mixed Liquor Suspended Solids (mg/L)

MT - Multi Tube

NF - Nano-filtration

O&G - Oil and Grease concentration (mg/L)

ONS - Organics Non Solids

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PAC - Powdered Activated Carbon

PES - Polyethersulfone

RO - Reverse Osmosis

SRT - Solid Retention Time (day)

T - Temperature (oC)

TDS - Total Dissolved Solids

TMP - Transmembrane Pressure (kpa)

TN - Total Nitrogen

TOC - Total Organic Carbon

UF - Ultra-filtration

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CHAPTER 1

INTRODUCTION

1.1 Research Background

Oily wastewater is known as one of the highly concerned pollution sources. Oil

and grease (O&G) are common pollutants in many industries such as steel, aluminum,

food processing, textile, leather, petrochemical and electroplating. These industries

report a high level of oil and grease in their effluent wastewater (Cheryana and

Rajagopalanb, 1998). There are several forms of oil and grease present in oily

wastewater: free, dispersed or emulsified (Rhee et al., 1987), in an oil-water mixture, oil

is classified based on its droplet size, free oil is characterized with droplets sizes > 150

μm. While dispersed oil has a droplet size between 20-150 μm and emulsified oil has a

droplet size < 20 μm. Oily wastewater is considered as a hazardous wastewater, due to

containing toxic substances, which include: petroleum hydrocarbons, polyaromatic

hydrocarbons and phenols.

Electroplating process involves the deposition of a thin layer onto a surface of

metal, by using electrochemical processes. Electroplating involves several steps such as:

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pretreatment, plating, rinsing, and drying. The overall wastewater stream generated from

electroplating process is extremely variable (1-500 liters per square meter) of surface

plated (World Bank Document, 1996). This produced wastewater is usually high in

heavy metals, oil and grease contents, these substances can be found in wastewater via

rinsing the finished parts or due to spillage and dumping of the process bath.

Conventional processes of treating oily wastewater include gravity separation,

skimming process, dissolved air floatation, coagulation and flocculation (Beisinger et

al., 1974). The physical treatment of oily wastewater such as gravity separator and

dissolved air flotation does not remove the pollutants completely but just transfers them

to a more concentrated waste (Scholz & Fuchs., 2000). Gravity separation is considered

the most common primary treatment of oily wastewater. This treatment is primarily used

to separate floatable oils from water. If the permeate from this process does not meet the

target limits, secondary treatment steps are required to reduce the levels of dissolved

emulsified and dispersed breaking of emulsions with chemicals followed by

sedimentation to reduce additional oil and grease. Some of the shortcomings of

conventional approaches are:

(i) The system is highly susceptible to changes in influent quality.

(ii) Skilled operators are required to achieve normal operation.

(iii) The equipment has a large footprint.

(iv) It produces a large volume of sludge.

(v) Mechanical problems due to clogging of chemical feeding line.

Therefore, there is a need to develop a more efficient treatment process based on

biological treatment to treat the oily wastewater.

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Membrane bioreactor (MBR) treatment system is one of the novel processes for

wastewater treatment in recent years. The first MBR system was commercially

developed in 1969 (Smith, 1969), for wastewater treatment and since then, the MBR

technology has evolved, and research on MBR system has increased, especially in the

past 5 years (Aileen et al., 2006). MBR treatment system combines both the activated

sludge process with a membrane filtration process. The bioreactor is operated similarly

to the conventional activated sludge system without the need for secondary clarification

steps like sand filtration.

Low pressure membrane filtration, either microfiltration (MF) or ultra-filtration

is used to separate effluent from activated sludge. The two MBR process configurations

are: submerged membrane (internal) and external circulation (side stream configuration).

The submerged MBR configuration is more widely used for wastewater treatment.

MBR treatment systems have many advantages over conventional processes

with their highly improved effluent quality which allows for water reuse. MBR process

can typically operate at higher mixed liquor suspended solid concentration (MLSS),

which results in less sludge production and stability against shock loading. Another

advantage for MBR system is that it eliminates the requirement for clarifying basins to

settle the biomass, allowing the system to be more compact.

Membrane fouling remains the most serious problem affecting the MBR system

performance. Fouling leads to a decline in effluent flux and higher energy consumption,

requiring more frequent membrane cleaning. A number of studies have been conducted

to find out the causes of membrane fouling phenomenon. Recent efforts have been done

to modify the MBR treatment system to make it more efficient in wastewater treatments.

Various techniques have been developed to minimize membrane fouling, such as

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periodic back washing and membrane aeration. Ueda et al., 1997, studied the effect of

aeration on membrane fouling. It was concluded that air bubbles prevent the deposition

on the membrane surface, therefore reducing fouling and providing better filterability

(Ueda et al., 1997).

1.2 Problem Statement

Basically there are 14 wastewater streams generated by the electroplating plant

in Skudai, Johor. The method of treatment depends on the type of wastewater generated.

The electroplating plant has reported a higher level of oil and grease in the effluent

wastewater of the FMNS (Free Metal Non Solids) and ONS (Organics Non Solids)

streams.

One of the latest worldwide interests for treating water and wastewater is by

membrane technology (MBR), MBR is a good option to treat industrial wastewater

because of the high effluent quality. This study will cover the removal of oil traces from

the FMNS and ONS wastewater streams in the electroplating plant using an MBR

treatment system, in order to meet the Malaysian standards for effluent wastewater

(Standard A, Environmental Quality Act, 1974).

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1.3 Objectives of the Study

This study aims to develop an MBR treatment system to treat the oily wastewater

from the FMNS and ONS streams in the operation of an electroplating plant in Skudai,

Johor, effectively to meet the effluent standards for electroplating industry in Malaysia.

Aerobic submerged membrane bioreactor (MBR) will be used for this study. This will

significantly increase the final water discharge quality of wastewater streams.

Specific objectives of this study for achieving the above purpose are:

(i) To determine the critical flux and operation flux for the MBR treatment

system to treat the oily wastewater.

(ii) To evaluate the performance of the MBR treatment system to treat the

oily wastewater in terms of removal efficiency of O&G, COD and BOD,

for both biological tank and final effluent.

(iii) To investigate the effects of MLSS concentration on MBR system

performance and fouling phenomena.

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1.4 Scopes of the Study

The scopes of this study are as follows:

(i) Determination of the critical flux was performed by using short-term

flux-step method. The operation flux was determined by considering the

critical flux value.

(ii) The effluent quality and removal efficiency were mainly determined in

terms of O&G, COD and BOD concentrations.

(iii) MLSS concentration was varied to investigate its effect on MBR system

performance to treat oily wastewater from ONS stream.