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BIOLOGICAL SLUDGE MINIMIZATIONAND BIOMATERIALS/BIOENERGYRECOVERY TECHNOLOGIES

BIOLOGICAL SLUDGEMINIMIZATIONAND BIOMATERIALS/BIOENERGYRECOVERY TECHNOLOGIES

Edited by

ETIENNE PAUL

YU LIU

Copyright � 2012 by John Wiley & Sons, Inc. All rights reserved.

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Library of Congress Cataloging-in-Publication Data:

Biological sludge minimization and biomaterials/bioenergy recovery technologies / edited by

Etienne Paul and Yu Liu.

p. cm.

Includes index.

ISBN 978-0-470-76882-2 (cloth)

1. Water treatment plant residuals—Purification. 2. Waste products as fuel. 3. Water—

Purification. 4. Biochemical engineering. I. Paul, Etienne, 1964- II. Liu, Yu, 1964-

TD899.W3B56 2012

628.3—dc23

2011045240Printed in the United States of America

10 9 8 7 6 5 4 3 2 1

CONTENTS

Preface xvii

Contributors xxi

1 Fundamentals of Biological Processes for Wastewater Treatment 1

Jianlong Wang

1.1 Introduction, 1

1.2 Overview of Biological Wastewater Treatment, 2

1.2.1 The Objective of Biological Wastewater Treatment, 2

1.2.2 Roles of Microorganisms in Wastewater Treatment, 3

1.2.3 Types of Biological Wastewater Treatment Processes, 4

1.3 Classification of Microorganisms, 4

1.3.1 By the Sources of Carbon and Energy, 4

1.3.2 By Temperature Range, 6

1.3.3 Microorganism Types in Biological Wastewater

Treatment, 7

1.4 Some Important Microorganisms in Wastewater Treatment, 8

1.4.1 Bacteria, 8

1.4.2 Fungi, 12

1.4.3 Algae, 15

1.4.4 Protozoans, 16

1.4.5 Rotifers and Crustaceans, 18

1.4.6 Viruses, 20

v

1.5 Measurement of Microbial Biomass, 21

1.5.1 Total Number of Microbial Cells, 21

1.5.2 Measurement of Viable Microbes on Solid Growth

Media, 22

1.5.3 Measurement of Active Cells in Environmental

Samples, 23

1.5.4 Determination of Cellular Biochemical Compounds, 24

1.5.5 Evaluation of Microbial Biodiversity by Molecular

Techniques, 24

1.6 Microbial Nutrition, 24

1.6.1 Microbial Chemical Composition, 25

1.6.2 Macronutrients, 27

1.6.3 Micronutrients, 28

1.6.4 Growth Factor, 29

1.6.5 Microbial Empirical Formula, 31

1.7 Microbial Metabolism, 31

1.7.1 Catabolic Metabolic Pathways, 32

1.7.2 Anabolic Metabolic Pathway, 38

1.7.3 Biomass Synthesis Yields, 39

1.7.4 Coupling Energy-Synthesis Metabolism, 41

1.8 Functions of Biological Wastewater Treatment, 42

1.8.1 Aerobic Biological Oxidation, 42

1.8.2 Biological Nutrients Removal, 45

1.8.3 Anaerobic Biological Oxidation, 50

1.8.4 Biological Removal of Toxic Organic Compounds

and Heavy Metals, 55

1.8.5 Removal of Pathogens and Parasites, 58

1.9 Activated Sludge Process, 59

1.9.1 Basic Process, 60

1.9.2 Microbiology of Activated Sludge, 61

1.9.3 Biochemistry of Activated Sludge, 66

1.9.4 Main Problems in the Activated Sludge Process, 67

1.10 Suspended- and Attached-Growth Processes, 69

1.10.1 Suspended-Growth Processes, 69

1.10.2 Attached-Growth Processes, 70

1.10.3 Hybrid Systems, 71

1.10.4 Comparison Between Suspended- and Attached-Growth

Systems, 72

1.11 Sludge Production, Treatment and Disposal, 74

1.11.1 Sludge Production, 74

1.11.2 Sludge Treatment Processes, 76

vi CONTENTS

1.11.3 Sludge Disposal and Application, 78

References, 79

2 Sludge Production: Quantification and Prediction for

Urban Treatment Plants and Assessment of Strategies

for Sludge Reduction 81Mathieu Sperandio, Etienne Paul, Yolaine Bessiere, and Yu Liu

2.1 Introduction, 81

2.2 Sludge Fractionation and Origin, 82

2.2.1 Sludge Composition, 82

2.2.2 Wastewater Characteristics, 83

2.3 Quantification of Excess Sludge Production, 88

2.3.1 Primary Treatment, 88

2.3.2 Activated Sludge Process, 90

2.3.3 Phosphorus Removal (Biological and

Physicochemical), 97

2.4 Practical Evaluation of Sludge Production, 99

2.4.1 Sludge Production Yield Variability with Domestic

Wastewater, 99

2.4.2 Influence of Sludge Age: Experimental Data Versus

Models, 100

2.4.3 ISS Entrapment in the Sludge, 103

2.4.4 Example of Sludge Production for a Different

Case Study, 104

2.5 Strategies for Excess Sludge Reduction, 106

2.5.1 Classification of Strategies, 106

2.5.2 Increasing the Sludge Age, 107

2.5.3 Model-Based Evaluation of Advanced

ESR Strategies, 109

2.6 Conclusions, 111

2.7 Nomenclature, 112

References, 114

3 Characterization of Municipal Wastewater and Sludge 117

Etienne Paul, Xavier Lefebvre, Mathieu Sperandio,

Dominique Lefebvre, and Yu Liu


3.2 Definitions, 119

CONTENTS vii

3.3 Wastewater and Sludge Composition and Fractionation, 120

3.3.1 Wastewater COD Fractions, 121

3.3.2 WAS COD Fractions, 122

3.3.3 ADS Organic Fractions, 122

3.4 Physical Fractionation, 123

3.4.1 Physical State of Wastewater Organic Matter, 123

3.4.2 Methods for Physical Fractionation of Wastewater

Components, 123

3.5 Biodegradation Assays for Wastewater and Sludge

Characterization, 124

3.5.1 Background, 124

3.5.2 Methods Based on Substrate Depletion, 125

3.5.3 Methods Based on Respirometry, 125

3.5.4 Anaerobic Biodegradation Assays, 128

3.6 Application to Wastewater COD Fractionation, 131

3.6.1 Global Picture of Fractionation Methods and

Wastewater COD Fractions, 131

3.6.2 Application of Physical Separation for Characterization

of Wastewater COD Fractions, 132

3.6.3 Biodegradable COD Fraction, 133

3.6.4 Relation Between Physical and Biological Properties

of Organic Fractions, 136

3.6.5 Unbiodegradable Particulate COD Fractions, 137

3.7 Assessment of the Characteristics of Sludge and Disintegrated

Sludge, 143

3.7.1 Physical Fractionation of COD Released from Sludge

Disintegration Treatment, 143

3.7.2 Biological Fractionation of COD Released from Sludge

Disintegration Treatment, 145

3.7.3 Biodegradability of WAS in Anaerobic Digestion, 145

3.7.4 Unbiodegradable COD in Anaerobic Digestion, 146


References, 149

4 Oxic-Settling-Anaerobic Process for Enhanced Microbial Decay 155

Qingliang Zhao and Jianfang Wang


4.2 Description of the Oxic-Settling-Anaerobic Process, 156

4.2.1 Oxic-Settling-Anaerobic Process, 156

4.2.2 Characteristics of the OSA Process, 157

viii CONTENTS

4.3 Effects of an Anaerobic Sludge Tank on the Performance

of an OSA System, 158

4.3.1 Fate of Sludge Anaerobic Exposure in an OSA

System, 158

4.3.2 Effect of Sludge Anaerobic Exposure on Biomass

Activity, 160

4.4 Sludge Production in an OSA System, 161

4.5 Performance of an OSA System, 162

4.5.1 Organic and Nutrient Removal, 162

4.5.2 Sludge Settleability, 163

4.6 Important Influence Factors, 164

4.6.1 Influence of the ORP on Sludge Production, 164

4.6.2 Influence of the ORP on Performance of an OSA

System, 164

4.6.3 Influence of SAET on Sludge Production, 166

4.6.4 Influence of SAET on the Performance of an OSA

System, 166

4.7 Possible Sludge Reduction in the OSA Process, 166

4.7.1 Slow Growers, 167

4.7.2 Energy Uncoupling Metabolism, 167

4.7.3 Sludge Endogenous Decay, 169

4.8 Microbial Community in an OSA System, 171

4.8.1 Staining Analysis, 172

4.8.2 FISH Analysis, 173

4.9 Cost and Energy Evaluation, 174

4.10 Evaluation of the OSA Process, 175

4.11 Process Development, 176

4.11.1 Sludge Decay Combined with Other Sludge Reduction

Mechanisms, 176

4.11.2 Improved Efficiency in Sludge Anaerobic Digestion, 177

4.11.3 Combined Minimization of Excess Sludge with

Nutrient Removal, 178

References, 179

5 Energy Uncoupling for Sludge Minimization: Pros and Cons 183

Bo Jiang, Yu Liu, and Etienne Paul


5.2 Overview of Adenosine Triphosphate Synthesis, 184

5.2.1 Electron Transport System, 184

CONTENTS ix

5.2.2 Mechanisms of Oxidative Phosphorylation, 185

5.3 Control of ATP Synthesis, 187

5.3.1 Diversion of PMF from ATP Synthesis to Other

Physiological Activities, 187

5.3.2 Inhibition of Oxidative Phosphorylation, 187

5.3.3 Uncoupling of Electron Transport and Oxidative

Phosphorylation, 188

5.4 Energy Uncoupling for Sludge Reduction, 189

5.4.1 Chemical Uncouplers Used for Sludge Reduction, 189

5.4.2 Uncoupling Activity, 198

5.5 Modeling of Uncoupling Effect on Sludge Production, 200

5.6 Sideeffects of Chemical Uncouplers, 202

5.7 Full-Scale Application, 204

References, 204

6 Reduction of Excess Sludge Production Using Ozonation

or Chlorination: Performance and Mechanisms of Action 209Etienne Paul, Qi-Shan Liu, and Yu Liu


6.2 Significant Operational Results for ESP Reduction with

Ozone, 210

6.2.1 Options for Combining Ozonation and Biological

Treatment, 210

6.2.2 ESP Reduction Performance, 212

6.2.3 Assessing Ozone Efficiency for Mineral ESP

Reduction, 215

6.3 Side Effects of Sludge Ozonation, 216

6.3.1 Outlet SS and COD, 216

6.3.2 N Removal, 218

6.4 Cost Assessment, 221

6.5 Effect of Ozone on Sludge, 222

6.5.1 Synergy Between Ozonation and Biological

Treatment, 222

6.5.2 Some Fundamentals of Ozone Transfer, 222

6.5.3 Sludge Composition, 224

6.5.4 Effect of Ozone on Activated Sludge: Batch Tests, 226

6.5.5 Effect of Ozone on Biomass Activity, 228

6.5.6 Competition for Ozone in Mixed Liquor, 231

x CONTENTS

6.6 Modeling Ozonation Effect, 233

6.7 Remarks on Sludge Ozonation, 236

6.8 Chlorination in Water and Wastewater Treatment, 236

6.8.1 Introduction, 236

6.8.2 Chlorination-Assisted Biological Process for Sludge

Reduction, 237

6.8.3 Effect of Chlorine Dosage on Sludge Reduction, 239

6.8.4 Chlorine Requirement, 240


References, 244

7 High-Dissolved-Oxygen Biological Process for Sludge Reduction 249

Zhi-Wu Wang


7.2 Mechanism of High-Dissolved-Oxygen Reduced Sludge

Production, 251

7.2.1 High-Dissolved-Oxygen Decreased Specific Loading

Rate, 251

7.2.2 High-Dissolved-Oxygen Uncoupled Microbial

Metabolism Pathway, 252

7.2.3 High-Dissolved-Oxygen Shifted Microbial

Population, 254

7.3 Limits of High-Dissolved-Oxygen Process for Reduced

Sludge Production, 255

References, 256

8 Minimizing Excess Sludge Production Through Membrane

Bioreactors and Integrated Processes 261Philip Chuen-Yung Wong


8.2 Mass Balances, 262

8.3 Integrated Processes Based on Lysis-Cryptic Growth, 266

8.3.1 Mass Balance Incorporating Sludge Disintegration

and Solubilization, 268

8.3.2 Thermal and Thermal-Alkaline Treatment, 274

8.3.3 Ozonation, 276

8.3.4 Sonication, 279

CONTENTS xi

8.4 Predation, 283

8.5 Summary and Concluding Remarks, 285

References, 286

9 Microbial Fuel Cell Technology for Sustainable Treatment

of Organic Wastes and Electrical Energy Recovery 291Shi-Jie You, Nan-Qi Ren, and Qing-Liang Zhao


9.2 Fundamentals, Evaluation, and Design of MFCs, 293

9.2.1 Principles, 293

9.2.2 Performance Evaluation, 293

9.2.3 MFC Configurations, 294

9.3 Performance of Anodes, 295

9.3.1 Electrode Materials, 295

9.3.2 Microbial Electron Transfer, 296

9.3.3 Electron Donors, 298

9.4 Cathode Performances, 299

9.4.1 Electron Acceptors, 300

9.4.2 Electrochemical Fundamentals of the Oxygen

Reduction Reaction, 302

9.4.3 Air-Cathode Structure and Function, 303

9.4.4 Electrocatalyst, 304

9.5 Separator, 306

9.6 pH Gradient and Buffer, 307

9.7 Applications of MFC-Based Technology, 309

9.7.1 Biosensors, 309

9.7.2 Hydrogen Production, 310

9.7.3 Desalination, 310

9.7.4 Hydrogen Peroxide Synthesis, 312

9.7.5 Environmental Remediation, 312

9.8 Conclusions and Remarks, 314

References, 315

10 Anaerobic Digestion of Sewage Sludge 319

Kuan-Yeow Show, Duu-Jong Lee, and Joo-Hwa Tay


10.2 Principles of Anaerobic Digestion, 320

10.2.1 Hydrolysis and Acidogenesis, 321

10.2.2 Methane Formation, 323

xii CONTENTS

10.3 Environmental Requirements and Control, 324

10.3.1 pH, 324

10.3.2 Alkalinity, 325

10.3.3 Temperature, 326

10.3.4 Nutrients, 326

10.3.5 Toxicity, 327

10.4 Design Considerations for Anaerobic Sludge Digestion, 329

10.4.1 Hydraulic Detention Time, 329

10.4.2 Solids Loading, 330

10.4.3 Temperature, 331

10.4.4 Mixing, 331

10.5 Component Design of Anaerobic Digester Systems, 331

10.5.1 Tank Configurations, 331

10.5.2 Temperature Control, 333

10.5.3 Sludge Heating, 333

10.5.4 Auxiliary Mixing, 334

10.6 Reactor Configurations, 336

10.6.1 Conventional Anaerobic Digesters, 336

10.6.2 Anaerobic Contact Processes, 338

10.6.3 Other Types of Configurations, 340

10.7 Advantages and Limitations of Anaerobic Sludge Digestion, 343

10.8 Summary and New Horizons, 344

References, 345

11 Mechanical Pretreatment-Assisted Biological Processes 349

Helene Carrere, Damien J. Batstone, and Etienne Paul


11.2 Mechanisms of Mechanical Pretreatment, 350

11.2.1 From Sludge Disintegration to Cell Lysis and

Chemical Transformation, 350

11.2.2 Specific Energy, 350


11.2.4 Grinding, 353

11.2.5 Shear-Based Methods: High-Pressure and Collision

Plate Homogenization, 353

11.2.6 Lysis Centrifuge, 353

11.3 Impacts of Treatment: Rate vs. Extent of Degradability, 353


11.3.2 Ultrasonication, 354

CONTENTS xiii

11.4 Equipment for Mechanical Pretreatment, 354



11.4.3 Shear-Based Methods: High-Pressure and Collision

Plate Homogenization, 358

11.4.4 Lysis Centrifuge, 359

11.5 Side Effects, 359

11.6 Mechanical Treatment Combined with Activated Sludge, 360

11.7 Mechanical Treatment Combined with Anaerobic Digestion, 361

11.7.1 Performances, 361

11.7.2 Dewaterability, 363

11.7.3 Full-Scale Performance and Market Penetration, 364

11.7.4 Energy Balance, 365

11.7.5 Nutrient Release and Recovery/Removal, 366

11.8 Conclusion, 367

References, 368

12 Thermal Methods to Enhance Biological Treatment Processes 373

Etienne Paul, Helene Carrere, and Damien J. Batstone


12.2 Mechanisms, 374

12.2.1 Effects of Heating on Cells, 374

12.2.2 Effect of Heating on Sludge, 376

12.2.3 Mechanisms of Thermal Pretreatment, 388

12.3 Devices for Thermal Treatment, 388

12.3.1 Low-Temperature Pretreatment, 389

12.3.2 High-Temperature Pretreatment, 390

12.4 Applications of Thermal Treatment, 390

12.4.1 Thermal Treatment Combined with Activated Sludge, 390

12.4.2 Thermal Pretreatment to Anaerobic Digestion, 394

12.5 Conclusions, 398

References, 399

13 Combustion, Pyrolysis, and Gasification of Sewage Sludge for

Energy Recovery 405Yong-Qiang Liu, Joo-Hwa Tay, and Yu Liu


13.2 Characteristics and Dewatering of Sewage Sludge, 406

xiv CONTENTS

13.3 Energy Recovery from Sludge, 408

13.3.1 Incineration, 408

13.3.2 Pyrolysis and Gasification, 416

13.3.3 Wet Oxidation, 419

13.3.4 Thermal Plasma Pyrolysis and Gasification, 420

References, 421

14 Aerobic Granular Sludge Technology for Wastewater Treatment 429

Bing-Jie Ni and Han-Qing Yu


14.2 Technological Starting Points: Cultivating Aerobic

Granules, 431

14.2.1 Substrate Composition, 431

14.2.2 Organic Loading Rate, 433

14.2.3 Seed Sludge, 433

14.2.4 Reactor Configuration, 433

14.2.5 Operational Parameters, 434

14.3 Mechanisms of the Aerobic Granulation Process, 436

14.3.1 Granulation Steps, 436

14.3.2 Selective Pressure, 437

14.4 Characterization of Aerobic Granular Sludge, 438

14.4.1 Biomass Yield and Sludge Reduction, 438

14.4.2 Formation and Consumption of Microbial

Products, 440

14.4.3 Microbial Structure and Diversity, 441

14.4.4 Physicochemical Characteristics, 442

14.5 Modeling Granule-Based SBR for Wastewater

Treatment, 447

14.5.1 Nutrient Removal in Granule-Based SBRs, 447

14.5.2 Multiscale Modeling of Granule-Based SBR, 450

14.6 Bioremediation of Wastewaters with Aerobic Granular Sludge

Technology, 452

14.6.1 Organic Wastewater Treatment, 452

14.6.2 Biological Nutrient Removal, 452

14.6.3 Domestic Wastewater Treatment, 454

14.6.4 Xenobiotic Contaminant Bioremediation, 454

14.6.5 Removal of Heavy Metals or Dyes, 455

14.7 Remarks, 456

References, 457

CONTENTS xv

15 Biodegradable Bioplastics from Fermented Sludge, Wastes,

and Effluents 465Etienne Paul, Elisabeth Neuhauser, and Yu Liu


15.1.1 Context of Poly(hydroxyalkanoate) Production

from Sludge and Effluents, 465

15.1.2 Industrial Context for PHA Production, 467

15.2 PHA Structure, 469

15.3 Microbiology for PHA Production, 469

15.4 Metabolism of PHA Production, 471

15.4.1 PHB Metabolism, 472

15.4.2 Metabolism for Other PHA Production, 475

15.4.3 Nutrient Limitations, 476

15.4.4 PHA Metabolism in Mixed Cultures, 477

15.4.5 Effect of Substrate in Mixed Cultures, 478

15.5 PHA Kinetics, 479

15.6 PHA Storage to Minimize Excess Sludge Production in

Wastewater Treatment Plants, 481

15.7 Choice of Process and Reactor Design for PHA

Production, 482

15.7.1 Criteria, 482

15.7.2 Anaerobic–Aerobic Process, 483

15.7.3 Aerobic Dynamic Feeding Process, 485

15.7.4 Fed-Batch Process Under Nutrient Growth

Limitation, 486

15.8 Culture Selection and Enrichment Strategies, 487

15.9 PHA Quality and Recovery, 489

15.10 Industrial Developments, 490

References, 492

Index 499

xvi CONTENTS

PREFACE

Activated sludge systems have been employed to treat a wide variety of wastewaters,

and most municipal wastewater treatment plants use it as the core of the treatment

process. The basic function of a biological treatment process is to convert organics

to carbon dioxide, water, and bacterial cells. The cells can then be separated from

the purified water and disposed of in a concentrated form called excess sludge.

Assuming that activated sludge has a conversion growth yield efficiency of 0.3 to

0.5mg dry weight per milligram of chemical oxygen demand (COD), 1 kg of COD

removed will generate 0.3 to 0.5 kg of dry excess sludge. As a result, a large amount

of sewage sludge is currently generated annually: around 10 million tons of dry

solids in the European Union, and 8 million tons of dry solids in the United States in

2010. In China, due to improvements in wastewater treatment systems, sludge

production is expected to increase radically and should have reached more than

11 million tons of dry solids in 2010. With the expansion of population and industry,

the increased excess sludge production is generating a real global challenge.

It should be realized that the excess sludge generated from the biological treatment

process is a secondary solid waste that must be disposed of in a safe and cost-

effective way. The ultimate disposal of excess sludge has been and continues to be

one of the most expensive problems faced by wastewater utilities; for example, the

treatment of the excess sludge may account for 25 to 65% of the total plant operation

cost. So far, sludge production and disposal are entering a period of dramatic change,

driven mainly by stringent environmental legislation. Sludge disposal to all the

established outlets could become increasingly difficult or, in the case of sea disposal,

will become illegal. Environmental pressures on sludge recycling to land may lead to

restrictions on applications in terms of nitrogen content and more stringent limits for

metals in soils.

xvii

At least four technical approaches have been seriously considered with respect

to excess sludge handling: (1) conversion of excess sludge to value-added materials

(e.g, construction materials and activated carbon); (2) recovery of useful resources

from sludge (e.g., production of fuel by-products through sludge melting or sludge

pyrolysis and extraction of useful chemicals from sludge (e.g. poly(hydroxyalk-

anoate)]; (3) reduction of sludge production from the wastewater treatment process

rather than the post-treatment or disposal of the sludge generated; and (4) sludge

incineration. In the past, sewage sludge was considered as a waste, today, it is treated

as amisplaced resource. Reducing sludge production can be done through a variety of

technologies targeting microbial growth yield or the biodegradability of the matter

accumulated. In most cases, mechanisms behind these technologies have not been

well understood, leading to limited full-scale applications. The waste-to-energy or

waste-to-useful materials strategies have received extensive attention. Energy recov-

ery from sewage sludge can be realized through anaerobic digestion for biogas

production (e.g., methane or hydrogen), pyrolysis and gasification for generating

syngas, and potentially, biochar or incineration with optimal drying for direct

production of electricity. Production of bioplastics from sewage sludge using a

mixed culture has attracted intensive research effort and indeed represents a new

option for sludge-to-high value material. Therefore, in this book we provide up-to-

date and comprehensive coverage of sludge reduction and valorization technologies

which are important for sustainable development of the global wastewater industry.

The book is organized into 15 chapters. Chapter 1 provides a comprehensive

review of the fundamentals of biological processes for wastewater treatment,

covering wastewater microbiology, microbial metabolism, and biological processes

that are the basis for better understanding of how excess sludge is produced. Chapter 2

is more focused on sludge production mechanisms and prediction. Prediction of

primary sludge and waste activated sludge production is one of the major tasks and

challenges in the design and operation of a wastewater treatment plant. Such

prediction is based on detailed characterization of influent organic and inorganic

components. Therefore, in Chapter 3, detailed characterization methods of waste-

water and sludge are presented.

Technologies for sludge reduction are discussed in Chapters 4 to 8, with the

primary focus on strategies to reduce microbial growth yield as well as to enhance

sludge disintegration in various biological processes, such as the oxic-settling-

anaerobic process for enhanced microbial decay (Chapter 4), the energy uncou-

pling-assisted activated sludge process (Chapter 5), the reduction of excess sludge

production through ozonation and chlorination (Chapter 6), the high-dissolved-

oxygen biological process for sludge reduction (Chapter 7), and membrane bior-

eactors as an alternative for minimizing excess sludge production (Chapter 8).

Microbial fuel cells for sustainable treatment of organic wastes and electrical

energy recovery are discussed in Chapter 9. For decades, in-plant anaerobic digestion

of sewage sludge has been employed for biogas recovery. Anaerobic digestion in

terms of process fundamentals, design, and operation is discussed in detail in

Chapter 10. During anaerobic digestion of sewage sludge, cell hydrolysis has

been identified as a limiting step in the overall process. In Chapter 11 we look

xviii PREFACE

into mechanical pretreatment of sewage sludge for enhanced biological treatment,

including ultrasonication, grinding, high-pressure homogenization, collision plate

homogenization, and lysis centrifuging.

Thermal treatment of sludge has been used in main activated sludge treatment

plants (sidestream treatment) or as a pretreatment in anaerobic sludge digestion.

Chapter 12 covers the representative thermal treatment technologies that have been

used successfully for the reduction of waste activated sludge as well as for enhanced

conversion of sludge to biogas. Waste sludge conversion to energy can be realized

through gasification, pyrolysis, and combustion of sewage sludge, as detailed in

Chapter 13. In Chapter 14, aerobic granulation technology, a novel biological process

for wastewater treatment, is discussed with a focus on its potential in sludge

reduction. Chapter 15 offers an excellent overview and technical details regarding

the production of biodegradable bioplastics from fermented sludge, wastes, and

effluents.

The audience for the book includes scientists, engineers, graduate students, and

everyone who has an interest in sludge reduction and valorization technologies.

We extend our gratitude to Ya-Juan Liu for her invaluable editorial assistance.

ETIENNE PAUL

YU LIU

PREFACE xix

CONTRIBUTORS

Damien J. Batstone, INRA, UR050, Advanced Water Management Centre, The

University of Queensland, Brisbane St Lucia, Queensland, Australia

Yolaine Bessiere, Universite de Toulouse; INSA, UPS, INP; LISBP, Toulouse,

France; INRA, UMR792, Ingenierie des Systemes Biologiques et des Procedes,

Toulouse, France; CNRS, UMR5504, Toulouse, France

Helene Carrere, INRA, UR050, Laboratoire de Biotechnologie de

l’Environnement, Narbonne, France

Bo Jiang, Division of Environmental and Water Resources Engineering, School of

Civil and Environmental Engineering, Nanyang Technological University,

Singapore

Duu-Jong Lee, Department of Chemical Engineering, National Taiwan University

of Science and Technology, Taipei, Taiwan

Dominique Lefebvre, Universite Paul Sabatier, Laboratoire de Biologie Appliquee

�a l’Agroalimentaire et �a l’Environnement, Auch, France

Xavier Lefebvre, Universite de Toulouse; INSA,UPS,INP; LISBP, 135 Avenue de

Rangueil, F-31077 Toulouse, France; INRA, UMR792, Ingenierie des Systemes

Biologiques et des Procedes, F-31400 Toulouse, France; CNRS, UMR5504,

F-31400 Toulouse, France

Qi-Shan Liu, School of Architecture and the Built Environment, Singapore Poly-

technic, Singapore

Yong-Qiang Liu, Institute of Environmental Science and Engineering, Nanyang

Technology University, Singapore

xxi

YuLiu, Division ofEnvironmental andWaterResources Engineering, School ofCivil

and Environmental Engineering, Nanyang Technological University, Singapore

Elisabeth Neuhauser, Universite de Toulouse; INSA, UPS, INP; LISBP, 135

Avenue de Rangueil, F-31077 Toulouse, France; INRA, UMR792, Ingenierie

des Systemes Biologiques et des Procedes, F-31400 Toulouse, France; CNRS,

UMR5504, F-31400 Toulouse, France

Bing-Jie Ni, Department of Chemistry, University of Science and Technology of

China, Hefei, China

Etienne Paul, Universite de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de

Rangueil, F-31077 Toulouse, France; INRA, UMR792, Ingenierie des Systemes

Biologiques et des Procedes, F-31400 Toulouse, France; CNRS, UMR5504,

F-31400, Toulouse, France

Nan-Qi Ren, State Key Laboratory of Urban Water Resource and Environment,

School of Municipal and Environmental Engineering, Harbin Institute of Tech-

nology, Harbin, China

Kuan-Yeow Show, Department of Environmental Engineering, Faculty of Engi-

neering and Green Technology, University Tunku Abdul Rahman, Jalan Univer-

sity, Bandar Barat, Kampar, Perak, Malaysia

Mathieu Sperandio, Universite de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue

de Rangueil, F-31077 Toulouse, France; INRA, UMR792, Ingenierie des Sys-

temes Biologiques et des Procedes, F-31400 Toulouse, France; CNRS,UMR5504,

F-31400 Toulouse, France

Joo-Hwa Tay, Department of Environmental Science and Engineering, Fudan

University, Shanghai, China

Jianfang Wang, School of Environmental Science and Engineering, Suzhou Uni-

versity of Science and Technology, Suzhou, China

Jianlong Wang, Laboratory of Environmental Technology, INET, Tsinghua Uni-

versity, Beijing, China

Zhi-Wu Wang, Bioscience Division, Oak Ridge National Laboratory, Oak Ridge,

Tennessee

Philip Chuen-Yung Wong, Division of Environmental and Water Resources Engi-

neering, School of Civil and Environmental Engineering, Nanyang Technological

University, Singapore

Shi-Jie You, State Key Laboratory of Urban Water Resource and Environment,

School of Municipal and Environmental Engineering, Harbin Institute of Tech-

nology, Harbin, China

Han-Qing Yu, Department of Chemistry, University of Science and Technology of

China, Hefei, China

Qing-Liang Zhao, State Key Laboratory of Urban Water Resource and Environ-

ment, School of Municipal and Environmental Engineering, Harbin Institute of

Technology, Harbin, China

xxii CONTRIBUTORS

1FUNDAMENTALS OF BIOLOGICALPROCESSES FOR WASTEWATERTREATMENT

JIANLONG WANG

Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, China

1.1 INTRODUCTION

In this chapter we offer an overview of the fundamentals and applications of

biological processes developed for wastewater treatment, including aerobic and

anaerobic processes. Beginning here, readers may learn how biosolids are even-

tually produced during the biological treatment of wastewater. The fundamentals of

biological treatment introduced in the first six sections of this chapter include (1) an

overview of biological wastewater treatment, (2) the classification of microorgan-

isms, (3) some importantmicroorganisms inwastewater treatment, (4)measurement

of microbial biomass, (5) microbial nutrition, and (6) microbial metabolism.

Following the presentation of fundamentals, the remaining four sections introduce

applications of biological wastewater treatment, including the functions of waste-

water treatment, the activated sludge process, the suspended and attached-growth

processes, and sludge production, treatment, and disposal. The topics covered

include (1) aerobic biological oxidation, (2) biological nitrification and denitrifi-

cation, (3) anaerobic biological oxidation, (4) biological phosphorus removal,

(5) biological removal of toxic organic compounds and heavy metals, and (6) bio-

logical removal of pathogens and parasites.

Biological Sludge Minimization and Biomaterials/Bioenergy Recovery Technologies, First Edition.Edited by Etienne Paul and Yu Liu.� 2012 John Wiley & Sons, Inc. Published 2012 by John Wiley & Sons, Inc.

1

1.2 OVERVIEW OF BIOLOGICALWASTEWATER TREATMENT

Biological treatment processes are the most important unit operations in wastewater

treatment. Methods of purification in biological treatment units are similar to the self-

purification process that occurs naturally in rivers and streams, and involve many of

the same microorganisms. Removal of organic matter is carried out by heterotrophic

microorganisms, which are predominately bacteria but also, occasionally, fungi. The

microorganisms break down the organic matter by two distinct processes, biological

oxidation and biosynthesis, both of which result in the removal of organic matter

from wastewater. Oxidation or respiration results in the formation of mineralized end

products that remain in wastewater and are discharged in the final effluent, while

biosynthesis converts the colloidal and soluble organic matter into particulate

biomass (new microbial cells) which can subsequently be separated from the treated

liquid by gravity sedimentation because it has a specific gravity slightly greater than

that of water.

The fundamental mechanisms involved in biological treatment are the same for all

processes. Microorganisms, principally bacteria, utilize the organic and inorganic

matter present in wastewater to support growth. A portion of materials is oxidized,

and the energy released is used to convert the remainingmaterials into new cell tissue.

The aim in this chapter will help students and technicians in environmental science

and engineering to recognize the role that environmental microbiology plays in

solving environmental problems. The principal purposes of this chapter are (1) to

provide fundamental information on themicroorganisms used to treat wastewater and

(2) to introduce the application of biological process fundamentals for the biological

treatment of wastewater.

1.2.1 The Objective of Biological Wastewater Treatment

From a chemical point of view, municipal wastewater or sewage contains (1) organic

compounds, such as carbohydrates, proteins, and fats; (2) nitrogen, principally in the

form of ammonia; and (3) phosphorus, which is principally in the form of phosphate

from human waste and detergents. In addition, municipal wastewater contains many

other types of particulate and dissolvedmatter, such as pathogens, plastics, sand, grit,

live organisms, metals, anions, and cations. All these constituents have to be dealt

with at wastewater treatment plants. However, not all of these are important for the

modeling and design of a wastewater treatment plant. Usually, the carbonaceous,

nitrogenous, and phosphorus constituents are mainly objects to be considered

because they influence biological activity and eutrophication in the receiving water.

Whenmunicipal wastewater is discharged to awater body, the organic compounds

will stimulate the growth of the heterotrophic organisms, causing a reduction in the

dissolved oxygen. When oxygen is present, the ammonia, which is toxic to many

higher life forms, such as fish and insects, will be converted to nitrate by the nitrifying

microorganisms, resulting in a further demand for oxygen. Depending on the volume

of wastewater discharged and the amount of oxygen available, the water body can

become anoxic. If the water body does become anoxic, nitrification of ammonia to

2 FUNDAMENTALS OF BIOLOGICAL PROCESSES FOR WASTEWATER TREATMENT

nitrate by the autotrophic bacteria will cease. However, some of the heterotrophic

bacteria will use nitrate instead of oxygen as a terminal electron acceptor and

continue their metabolic reactions. Depending on the relative amount of organics and

nitrate, the nitrate may become depleted. In this case, the water will become

anaerobic and transfer to fermentation. When the organic compounds of the

wastewater have been depleted, the water body will begin to recover, clarify, and

again becomes aerobic. But most of the nutrients, nitrogen (N) and phosphorus (P),

remain and stimulate aquatic plants such as algae to grow. Only when the nutrients N

and P are depleted and the organic compounds sufficiently reduced can the water

body became eutrophically stable again.

From these considerations, the overall objectives of the biological treatment of

domestic wastewater are to (1) transform (i.e., oxidize) dissolved and particulate

biodegradable constituents into acceptable end products that will no longer sustain

heterotrophic growth; (2) transform or remove nutrients, such as ammonia, nitrate,

and particularly phosphates; and (3) in some cases, remove specific trace organic

constituents and compounds. For industrial wastewater treatment, the objective is to

remove or reduce the concentration of organic and inorganic compounds. Because

some of the constituents and compounds found in industrial wastewater are toxic to

microorganisms, pretreatment may be required before industrial wastewater can be

discharged to a municipal collection system.

1.2.2 Roles of Microorganisms in Wastewater Treatment

The biological wastewater treatment is carried out by a diversified group of

microorganisms. It is the bacteria that are primarily responsible for the oxidation

of organic compounds. However, fungi, algae, protozoans, and higher organisms all

have important roles in the transformation of soluble and colloidal organic pollutants

into carbon dioxide and water as well as biomass. The latter can be removed from the

liquid by settlement prior to discharge to a natural watercourse.

Many water pollution problems and solutions deal with microorganisms. To solve

water pollution problems, environmental scientists require a background in micro-

biology. By understanding how microbes live and grow in an environment, envi-

ronmental engineers can develop the best possible solution to biological waste

problems. After construction of the desired treatment facilities, environmental

engineers are responsible to operate them properly to produce the desired results

at the least cost.

Learning to use mixtures of microorganisms to control the major environmental

systems has become a major challenge for environmental engineers. Environmental

microbiology should help operators of municipal wastewater and industrial waste

treatment plants gain a better understanding of how their biological treatment unit

work and what should be done to obtain maximum treatment efficiency. Design

engineers should gain a better understanding of how microbes provide the desired

treatment and the limitations for good design. Even regulatory personnel can obtain a

better understanding of the limits of their regulations and what concentration of

contaminants can be allowed in the environment.

OVERVIEW OF BIOLOGICAL WASTEWATER TREATMENT 3

The stabilization of organic matter is accomplished biologically using a variety of

microorganisms, which convert the colloidal and dissolved carbonaceous organic

matter into various gases and into protoplasm. It is important to note that unless the

protoplasm produced from the organic matter is removed from the solution, complete

treatment will not be accomplished because the protoplasm, which itself is organic,

will be measured as biological oxygen demand (BOD) in the effluent.

1.2.3 Types of Biological Wastewater Treatment Processes

Biological treatment processes are typically divided into two categories according

to the existing state of the microorganisms: suspended-growth systems and

attached-growth systems. Suspended systems are more commonly referred to as

activated sludge processes, of which several variations and modifications exist.

Attached-growth systems differ from suspended-growth systems in that microor-

ganisms attached themselves to a medium, which provides an inert support.

Trickling filters and rotating biological contactors are most common forms of

attached-growth systems.

The major biological processes used for wastewater treatment are typically

divided into four groups: aerobic processes, anoxic processes, anaerobic processes,

and a combination of aerobic/anoxic or anaerobic processes. The individual pro-

cesses are further subdivided into two categories: suspended-growth systems and

attached-growth systems, according to the existing state of microorganisms in the

wastewater treatment systems.

1.3 CLASSIFICATION OF MICROORGANISMS

Conventional taxonomic methods used to identify a bacterium rely on physical

properties of the bacteria and metabolic characteristics. To apply this approach, a

pure culture must first be isolated. The culture may be isolated by serial dilution and

growth in selective growth media. The cells are harvested and grown as pure culture

using sterilization techniques to prevent contamination. Historically, the types of

tests that are used to characterize a pure culture include (1) microscopic observations,

to determine morphology (size and shape); (2) Gram staining technique; (3) the type

of electron acceptor used in oxidation–reduction reactions; (4) the type of carbon

source used for cell growth; (5) the ability to use various nitrogen and sulfur sources;

(6) nutritional needs; (7) cell wall chemistry; (8) cell characteristics, including

pigments, segments, cellular inclusions, and storage products; (9) resistance to

antibiotics; and (10) environmental effects of temperature and pH. An alternative

to taxonomic classification is a newer method, termed phylogeny.

1.3.1 By the Sources of Carbon and Energy

Microorganisms may be classified by their trophic levels, that is, by their energy and

carbon source and their relationship to oxygen. Energy is derived principally from


two sources and carbon from two sources, and these form convenient criteria to

categorize organisms, in particular the microorganisms involved in water quality

control and wastewater treatment. Microbes can be grouped nutritionally on the basis

of how they satisfy their requirements for carbon, energy, and electrons or hydrogen.

Indeed, the specific nutritional requirements of microorganisms are used to distin-

guish one microbe from another for taxonomic purposes.

Microorganismsmay be grouped on the basis of their energy sources. Two sources

of energy are available to microorganisms. Microbes that oxidize chemical com-

pounds (either organic or inorganic) for energy are called chemotrophs; those that use

sunlight as their energy sources are called phototrophs. A combination of these terms

with those employed in describing carbon utilization results in the following

nutritional types:

1. Chemoautotrophs. microbes that use inorganic chemical substances as a

source of energy and carbon dioxide as the main source of carbon.

2. Chemoheterotrophs. microbes that use organic chemical substances as a

source of energy and organic compounds as the main source of carbon.

3. Photoautotrophs. microbes that use light as a source of energy and carbon

dioxide as the main source of carbon.

4. Photoheterotrophs. microbes that use light as a source of energy and organic

compounds as the main source of carbon.

Microorganisms also have two sources of hydrogen atoms or electrons. Those that

use reduced inorganic substances as their electron source are called lithotrophs.

Those microbes that obtain electrons or hydrogen atoms (each hydrogen atom has

one electron) from organic compounds are called organotrophs.

A combination of the terms above describes four nutritional types of

microorganisms:

1. Photolithotrophic autotrophs. also called photoautotrophs, they use light

energy and carbon dioxide as their carbon source, but they employ water as

the electron donor and release oxygen in the process, such as cyanobacteria,

algae, and green plants.

2. Photo-organotrophic heterotrophs. also called photoheterotrophs, they use

radiant energy and organic compounds as their electron/hydrogen and carbon

donors, such as purple and green non-sulfur bacteria.

3. Chemolithotrophic autotrophs. also called chemoautotrophs, they use

reduced inorganic compounds, such as nitrogen, iron, or sulfur molecules,

to derive both energy and electrons/hydrogen. They use carbon dioxide

as their carbon source, such as the nitrifying, hydrogen, iron, and sulfur

bacteria.

4. Chemo-organotrophic heterotrophs. also called chemoheterotrophs, they use

organic compounds for energy, carbon, and electrons/hydrogen, such as

animals, most bacteria, fungi, and protozoans.

CLASSIFICATION OF MICROORGANISMS 5

Chemotrophs are important in the transformations of the elements, such as the

conversion of ammonia to nitrate and sulfur to sulfate, which occur continually in

nature. Usually, a particular species of microorganism belongs to only one of the four

nutritional types. However, some microorganisms have great metabolic flexibility

and can alter their nutritional type in response to environmental change. For example,

many purple non-sulfur bacteria are photoheterotrophs in the absence of oxygen, and

they can become chemoheterotrophs in the presence of oxygen. When oxygen is low,

photosynthesis and oxidative metabolism can function simultaneously.

In the biosphere, the basic source of energy is solar radiation. The photosynthetic

autotrophs (e.g., algae) are able to fix some of this solar energy into complex organic

compounds (cell mass). These complex organic compounds then form the energy

source for other organisms––the heterotrophs. The general process whereby the

sunlight energy is trapped and then flows through the ecosystem (i.e., the process

whereby life forms grow) is a sequence of reduction–oxidation (“redox” reactions).

In chemistry the acceptance of electrons by a compound (organic or inorganic) is

known as reduction and the compound is said to be reduced, and the donation of

electrons by a compound is known as oxidation and the compound is said to be

oxidized. Because the electrons cannot remain as entities on their own, the electrons

are always transferred directly from one compound to another so that the reduction–

oxidation reactions, or electron donation–electron acceptance reactions, always

operate as couples. These coupled reactions, known as redox reactions, are the

principal energy transfer reactions that sustain temporal life. The link between redox

reactions and energy transfer can best be illustrated by following the flow of energy

and matter through an ecosystem.

1.3.2 By Temperature Range

Temperature has an important effect on the selection, survival, and growth of

microorganisms. Microorganisms may also be classified by their preferred temper-

ature regime. Each species of bacteria reproduces best within a limited range of

temperatures. In general, optimal growth for a particular microorganism occurs

within a fairly narrow range of temperature, although most microorganisms can

survive within much broader limits. Temperatures below the optimum typically have

a more significant effect on growth rate than do temperatures above the optimum.

The microbial growth rates will double with approximately every 10�C increase in

temperature until the optimum temperature is reached. According to the temperature

range in which they function best, bacteria may be classified as psychrophilic,

mesophilic, or thermophilic. Typical temperature ranges for microorganisms in each

of these categories are presented in Table 1.1.

Three temperature ranges are used to classify them. Those that grow best at

temperatures below 20�C are called psychrophiles. Mesophiles grow best at tem-

peratures between 25 and 40�C. Between 55 and 65�C, the thermophiles grow best.

The growth range of facultative thermophiles extends from the thermophilic into the

mesophilic range. These ranges are qualitative and somewhat subjective. Bacteria

will grow over a range of temperatures and will survive at a very large range of


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