9781119312369

Provides an excellent balance between theory and applications in the ever-evolving field of water and wastewater treatment

Completely updated and expanded, this is the most current and comprehensive textbook available for the areas of water and wastewater treatment, covering the broad spectrum of technologies used in practice today—ranging from commonly used standards to the latest state of the art innovations. The book begins with the fundamentals—applied water chemistry and applied microbiology—and then goes on to cover physical, chemical, and biological unit processes. Both theory and design concepts are developed systematically, combined in a unified way, and are fully supported by comprehensive, illustrative examples.

Theory and Practice of Water and Wastewater Treatment, 2nd Edition:

Addresses physical/chemical treatment, as well as biological treatment, of water and wastewater
Includes a discussion of new technologies, such as membrane processes for water and wastewater treatment, fixed-film biotreatment, and advanced oxidation
Provides detailed coverage of the fundamentals: basic applied water chemistry and applied microbiology
Fully updates chapters on analysis and constituents in water; microbiology; and disinfection
Develops theory and design concepts methodically and combines them in a cohesive manner
Includes a new chapter on life cycle analysis (LCA)

Theory and Practice of Water and Wastewater Treatment, 2nd Edition is an important text for undergraduate and graduate level courses in water and/or wastewater treatment in Civil, Environmental, and Chemical Engineering.

RONALD DROSTE, PHD, is an Emeritus Professor in the Department of Civil Engineering at the University of Ottawa, and a Fellow of the Canadian Society for Civil Engineering (CSCE).

RONALD GEHR, PHD, is an Associate Professor (Post-retirement) in the Department of Civil Engineering and Applied Mechanics at McGill University and a Fellow of the Canadian Society for Civil Engineering (CSCE).

Acknowledgments XXI

Preface XXIII

Abbreviations and Acronyms Used in the Text XXV

About the Companion Website XXXIII

Section I: Chemistry 1

1 Basic Chemistry 3

1.1 Definitions 3

1.2 The Expression of Concentration 4

1.3 Ions and Molecules in Water 5

1.3.1 Oxidation Number 5

1.4 Balancing Reactions 9

1.5 Oxidation–Reduction Reactions 10

1.6 Equilibrium 12

1.7 Conductivity and Ionic Strength 13

1.7.1 Conductance 14

1.7.2 Ionic Strength 14

1.8 Chemical Kinetics 15

1.8.1 Other Formulations 16

Consecutive or Series 16

Parallel 17

Retardant 17

Autocatalytic 17

Catalysis 18

1.8.2 The Effect of Temperature on Rate of Reaction 19

1.9 Gas Laws 19

1.10 Gas Solubility: Henry’s Law 20

1.11 Solubility Product 23

1.12 Complexes 25

1.13 Nuclear Chemistry 27

1.13.1 Radioactivity Units 27

Questions and Problems 30

References 33

2 The Thermodynamic Basis for Equilibrium 35

2.1 Thermodynamic Relations 35

2.1.1 Free Energy 35

Expression of Concentration in Equilibrium Expressions 39

2.1.2 Enthalpy and Temperature Effects on the Equilibrium Constant 42

2.2 Redox Potentials 43

2.2.1 Cell or Couple Potential 46

2.2.2 Oxidation–Reduction Potential and System Potential 48

2.3 Corrosion 49

2.3.1 Microbial Corrosion 51

2.3.2 Corrosion Prevention from External Environmental Factors 52

Galvanic Cathodic Protection 52

Electrolytic (or Impressed Current) Cathodic Protection 53

Questions and Problems 53

References 55

3 Acid–Base Chemistry 57

3.1 pH 57

3.2 Acids and Bases 58

3.2.1 Conjugate Acids and Bases 61

3.3 Equivalents and Normality 61

3.4 Solution of Multiequilibria Systems 62

3.5 Buffers 63

3.5.1 Dilution of a Buffered Solution 65

3.5.2 The Most Effective pH for a Buffer 65

3.6 Acid–Base Titrations 66

3.6.1 Titration of Strong Acids and Bases 66

3.6.2 Titration of Weak Acids and Bases 68

3.6.3 Indicating the Endpoint of an Acid–Base Titration 71

3.7 Natural Buffering of Waters from Carbon Dioxide and Related Compounds 73

3.7.1 Acidity and Alkalinity 74

Questions and Problems 76

References 78

4 Organic and Biochemistry 81

4.1 Carbon 81

4.2 Properties of Organic Compounds 81

4.3 Functional Groups 82

4.4 Types of Organic Compounds 83

4.4.1 Aliphatic Compounds 83

Aldehydes and Ketones 83

Alcohols, Esters, and Ethers 83

4.4.2 Nitrogen-containing Compounds 83

4.5 Aromatic Compounds 84

4.5.1 Compounds of Sulfur 85

4.6 Naturally Occurring Organic Compounds 85

4.6.1 Carbohydrates 85

4.6.2 Proteins 86

4.6.3 Fats and Oils 86

4.7 Biochemistry 86

4.8 Glycolysis 87

4.9 The Tricarboxylic Acid Cycle 88

4.10 Enzyme Kinetics 89

Questions and Problems 91

References 93

5 Analyses and Constituents in Water 95

5.1 Titration 95

5.1.1 Complex and Precipitate Formation Titrations 95

5.1.2 Redox Titrations and Potentiometric Analyses 96

5.1.3 Indicators for Potentiometric Analysis 98

5.2 Colorimetric Analyses 99

5.2.1 The Beer–Lambert Laws for Light Transmittance 99

5.3 Physical Analyses 99

5.3.1 Solids 99

5.3.2 Turbidity and Color 101

5.4 Determination of Organic Matter 102

5.4.1 Chemical Oxygen Demand 103

General Reaction for COD 104

Interferences with the COD Test 105

5.4.2 Biochemical Oxygen Demand 105

Effects of Temperature on BOD Exertion 108

Carbonaceous and Nitrogenous BOD 109

Laboratory Methods for Determining BOD 110

Limitations of the BOD Test for Biological Wastewater Treatment Process Design 110

Analysis of a BOD Progression 111

5.4.3 Total Organic Carbon 113

Questions and Problems 113

References 118

Section II: Microorganisms in Water and Water Quality 119

6 Microbiology 121

6.1 Groups of Microorganisms and the Phylogenetic Tree 121

6.2 Bacteria and Archaea 121

6.2.1 Classification of Bacteria 124

Taxonomy 124

Metabolic Requirements 125

Oxygen Requirements 125

Temperature 126

Salt and Sugar Concentrations 127

pH 127

6.3 Eukaryotes 127

6.3.1 Algae 128

6.3.2 Fungi 129

6.3.3 Protists 129

6.4 Other Microorganisms 130

6.4.1 Viruses and Phages 130

6.4.2 Rotifers 131

6.4.3 Worms 131

6.5 Determining the Growth of Microorganisms 132

6.5.1 Growth of Pure Cultures 132

6.5.2 Growth of Mixed Cultures 135

6.5.3 Viability and Mass in Growing Cultures 136

6.5.4 Enumeration of Microorganisms 136

Plate Counts 136

Practical Considerations in Determining Mean Values 140

6.5.5 Microbial Genomics and Molecular Microbiology Tools 141

Phylogenetic Microbial Community Composition Analysis 141

Functional Analysis 142

Questions and Problems 143

References 145

7 Water, Wastes, and Disease 147

7.1 Agents of Disease 147

7.1.1 Bacterial Pathogens 147

7.1.2 Viral Pathogens 149

7.1.3 Protozoan Pathogens 150

7.1.4 Helminths 150

7.1.5 Insect and Animal Vectors of Disease 153

7.2 Indicator, Test, and Model Microorganisms 153

7.3 Indicators of Fecal Contamination 155

7.4 Indicator Microorganisms 156

7.4.1 Coliforms: Total, Thermotolerant, and E. coli 156

7.4.2 Enterococci 157

7.5 Surrogates 157

7.6 Survival of Microorganisms in the Aquatic Environment 159

7.7 Minimum Infective Dose 162

Questions and Problems 163

References 164

8 Water Constituents and Quality Standards 167

8.1 Toxicity of Elements and Compounds 167

8.2 Contaminants in Water 170

8.2.1 Emerging Contaminants 171

8.2.2 Common Contaminants 173

Aluminum 173

Nitrate 173

Fluoride 173

Detergents 174

8.2.3 Carcinogens 174

8.2.4 Radioactive Constituents 175

8.3 Taste and Odor 176

8.4 Bases for Standards 178

8.4.1 Risk Assessment for Microbial Infection 179

8.4.2 Determination of Carcinogenicity 180

8.4.3 Toxicity Determination 182

8.4.4 Environmental Water Quality Standards 184

8.5 Standards for Drinking Water 184

8.5.1 International Drinking Water Standards 185

8.5.2 US Safe Drinking Water Act 185

8.5.3 Canadian Water Quality Guidelines 186

8.6 Comparison of Drinking Water Standards 187

8.6.1 Microbiological Parameters 187

WHO Guidelines for Microbiological Quality 187

United States Standards for Microbiological Quality 187

Canadian Guidelines for Microbiological Quality 188

8.6.2 Chemical and Physical Qualities 188

8.6.3 Aesthetic Quality 188

8.6.4 Radiological Constituents 188

8.6.5 Other Water Standards 192

8.7 Water Consumption 192

8.8 Canadian Federal Wastewater Quality Guidelines 195

8.9 Wastewater Characteristics 195

Greywater 196

8.10 Wastewater Production 197

Questions and Problems 198

References 200

Section III: Water and Wastewater Treatment 205

9 Water and Wastewater Treatment Operations 207

9.1 Water Treatment Operations 207

Microbial Contaminants 212

Reservoirs 213

9.1.1 Home Water Treatment Units 216

9.2 Wastewater Treatment Unit Operations 216

9.3 Hydraulic Design of Water and Wastewater Treatment Plants 225

Flow in Pressurized Pipes 225

Flow in Open Channels 226

Other Losses 227

Questions and Problems 230

References 232

10 Mass Balances and Hydraulic Flow Regimes 235

10.1 Setup of Mass Balances 235

10.1.1 Mixing Characteristics of Basins 236

10.1.2 Mass Balances for PF Reactors 237

Method I 238

Method II 239

Method III 239

10.1.3 Mass Balances and Reaction for CM Basins 242

10.1.4 Batch Processes 244

10.2 Flow Analysis of CM and PF Reactors 245

10.2.1 Tracer Analysis of Complete Mixed Reactors 245

10.2.2 Tracer Analysis of Plug Flow 247

10.2.3 Complete Mixed Reactors in Series 247

10.2.4 Other Flow Irregularities: Dead Volume and Short-circuiting 248

10.2.5 Typical Flow Characteristics of Basins 249

10.2.6 Measurement of Dispersion 250

10.3 Detention Time in Vessels 250

10.3.1 Average Detention Time 251

10.3.2 The Effects of Flow Recycle on Detention Time 251

10.3.3 The Effects of Recycle on Mixing 253

10.4 Flow and Quality Equalization 253

10.5 System Material Balances 256

Questions and Problems 266

References 271

Section IV: Physical–Chemical Treatment Processes 273

11 Screening and Sedimentation 275

11.1 Screens and Bar Racks 275

11.1.1 Screens for Water Treatment Plants 276

11.1.2 Screens at Wastewater Treatment Plants 277

11.1.3 Microstrainers 277

11.2 Sedimentation 278

11.2.1 Particle Settling Velocity 279

11.3 Grit Chambers 281

11.3.1 Horizontal Flow Grit Chambers 282

Channel with Varying Cross Section 283

Design Notes for a Parabolic Grit Chamber 284

11.3.2 Aerated Grit Chambers 290

11.3.3 Square Tank Degritter 292

11.3.4 Vortex Grit Removal Devices 293

Grit Washing 294

11.4 Type I Sedimentation 294

11.4.1 Theory 294

11.5 Type II Sedimentation 297

11.5.1 Laboratory Determination of Settling Velocity Distribution 298

11.5.2 Type II Sedimentation Data Analysis 298

11.5.3 Alternative Method for Calculating Total Removal 302

11.5.4 Sizing the Basin 303

11.6 Tube and Lamella Clarifiers 303

11.7 Weir–Launder Design 309

11.8 Clarifier Design for Water and Primary Wastewater Treatment 313

11.8.1 Design Ranges for Typical Clarifiers for Water and Wastewater Treatment 313

11.8.2 Chemically Enhanced Primary Treatment 315

11.8.3 Depth in Sedimentation Basins 318

11.9 Inlet Hydraulics for Sedimentation Basins 319

11.9.1 Flow Distributions 319

11.9.2 Inlet Baffling 322

Questions and Problems 323

References 328

12 Mass Transfer and Aeration 331

12.1 Fick’s Law 331

12.2 Gas Transfer 332

12.2.1 Calculating the Mass Transfer Coefficient 335

12.2.2 The Effects of pH on Mass Transfer 336

12.3 Aeration in Water and Wastewater Treatment 336

12.3.1 Hazards Associated with Oxygen, Carbon monoxide, and Hydrogen sulfide 338

12.4 Design of Aeration Systems 339

12.4.1 Gravity Aerators 339

12.4.2 Spray Aerators 341

12.4.3 Diffused Aerators 344

Questions and Problems 346

References 348

13 Coagulation and Flocculation 351

13.1 Coagulation 351

Recovery of Alum and Iron Coagulants 355

13.2 Mixing and Power Dissipation 356

13.3 Mixers 358

13.3.1 Mechanical Mixers 359

13.3.2 Pneumatic Mixers 362

13.3.3 Hydraulic Mixers 363

Venturi Sections and Hydraulic Jumps 363

13.4 Flocculators 368

13.4.1 Paddle Flocculators 369

13.4.2 Vertical-Shaft Turbine Flocculators 375

13.4.3 Pipes 376

13.4.4 Baffled Channels 376

13.4.5 Upflow Solids Contact Clarifier 377

13.4.6 Alabama Flocculator 377

13.4.7 Spiral Flow Tanks 378

13.4.8 Pebble Bed Flocculators 379

13.4.9 Ballasted Flocculation 380

Questions and Problems 382

References 384

14 Filtration 387

14.1 Slow Sand Filters and Rapid Filters 388

14.2 Filtering Materials 389

14.2.1 Grain Size and Distribution 389

14.3 Headloss in Filters 394

14.3.1 Grain Size Distribution and Headloss 397

14.4 Backwashing Filters 398

14.4.1 Total Head Requirements for Backwashing 400

Losses in the Expanded Media 400

14.4.2 Backwash Velocity 401

Method 1 401

Method 2 402

Headloss and Expansion in a Stratified Bed 405

14.5 Support Media and Underdrains in Rapid Filters 409

Other Design Features of Filters 411

Auxiliary Wash and Air Scour Systems 411

14.6 Filter Beds for Water and Wastewater Treatment 412

14.7 Air Binding of Filters 415

14.8 Rapid Filtration Alternatives 417

14.8.1 Single-medium and Multimedia Filters 417

14.8.2 Constant- and Declining-rate Filtration 417

14.8.3 Direct Filtration 418

14.9 Pressure Filters 419

14.10 Slow Sand Filters 419

14.10.1 Slow Sand Filters for Tertiary Wastewater Treatment 421

14.11 Biological Filtration for Water Treatment 421

Questions and Problems 424

References 427

15 Physical–Chemical Treatment for Dissolved Constituents 431

15.1 Water Softening 431

15.2 Lime–Soda Softening 433

15.2.1 Treatment Methods for Lime–Soda Hardness Removal 434

15.2.2 Bar Graphs 439

Lime Recovery and Sludge Reduction 441

15.3 Corrosion Prevention in Water Supply Systems 441

15.3.1 The Langelier Index Misconception 443

15.4 Iron and Manganese Removal 447

15.4.1 Greensand 448

15.4.2 Aeration 449

15.4.3 Sequestering Iron and Manganese 449

15.4.4 Biological Removal of Iron and Manganese 449

15.5 Phosphorus Removal from Wastewater by Chemical Precipitation 450

15.5.1 Removal of Phosphorus by Chemically Reactive Species 452

15.6 Removal of Arsenic and Metals 453

15.6.1 Metals Removal 453

15.6.2 Arsenic Removal 454

15.7 Advanced Oxidation Processes 455

15.8 Ion Exchange 456

15.8.1 Activated Alumina 457

15.8.2 Ammonia and Nitrate Removal by Ion Exchange 458

15.9 Fluoridation and Defluoridation 458

15.10 Membrane Processes 460

15.10.1 Assessment of Water Suitability for Membrane Treatment 466

15.10.2 Concentrate Disposal 468

15.10.3 Membranes for Water Treatment 468

Microfiltration and Ultrafiltration Systems 468

Nanofiltration and Reverse Osmosis Treatment 469

Electrodialysis 472

15.11 Activated Carbon Adsorption 472

15.11.1 Activated Carbon – Preparation and Characteristics 473

15.11.2 Adsorption Isotherms 474

15.11.3 Granular Activated Carbon Adsorbers 477

15.12 Design of Fixed-bed Adsorbers 478

15.12.1 Rate Formulation for Adsorption 479

15.12.2 Theory of Fixed-bed Adsorber Systems 480

The Capacity Utilized in the Adsorption Zone 481

Competitive Adsorption 490

15.12.3 Bed-depth Service Time Method 490

15.12.4 Rapid Small-Scale Column Tests 494

15.12.5 Granular Activated Carbon Reactors in Series 498

15.12.6 Design of a Suspended Media PAC or GAC Continuous Flow Reactor 498

Questions and Problems 499

References 503

16 Disinfection 509

16.1 Kinetics of Disinfection 510

16.2 Chlorination 512

16.2.1 Chemistry of Chlorine 512

16.2.2 Measurement of Free and Residual Chlorine 516

16.2.3 Chlorine Decay 517

16.2.4 Drinking Water Disinfection by Chlorine 518

16.2.5 Wastewater Disinfection by Chlorine 519

16.2.6 Design of Contacting Systems for Chlorine 521

16.2.7 Disinfection as the Sole Treatment of Surface Water 521

16.2.8 Other Applications of Chlorine 522

16.2.9 Dechlorination 522

16.3 Chloramines 523

16.4 Chlorine Dioxide 524

16.4.1 Chlorine Dioxide Doses as a Primary Disinfectant 525

16.4.2 Chlorine Dioxide for Pre-disinfection or for Residual Disinfection 525

16.4.3 Generation of Chlorine Dioxide 526

16.5 Peracids: Peracetic Acid (PAA) and Performic Acid (PFA) 527

16.5.1 Peracetic Acid 527

Kinetics of Disinfection Using PAA 528

Measuring PAA Residuals 529

Applications for Wastewater Disinfection 530

Chemical Disinfection Process Control 530

16.5.2 Performic Acid 531

16.6 Ozone 531

16.6.1 Determining the Appropriate Ozone Dose 532

16.6.2 Ozone Generation 533

16.6.3 Ozone Dissolution Systems 534

16.6.4 Ozone Contactor Basins 535

16.6.5 Ozone Chemistry: Mass Transfer Coefficients and Radicals Production 536

16.6.6 Ozone for Wastewater Disinfection 537

16.6.7 Ozone for Destruction of Micropollutants 538

16.7 Ultraviolet Radiation 538

16.7.1 Mechanism of UV Disinfection 538

16.7.2 Repair of UV Damage 539

Photo Repair 539

Dark Repair 540

16.7.3 Interferences 540

16.7.4 Generation of Ultraviolet Light and Ultraviolet Reactors 541

16.7.5 Disinfection Kinetics 541

16.7.6 Disinfection Doses (or Fluences) 542

16.7.7 Determination of UV Fluence 542

16.7.8 Ultraviolet Reactors 545

16.8 Point-of-use Disinfectants: Solar Disinfection (SODIS), with or without Photoreactants such as TiO2 547

16.9 Disinfection Byproducts 548

16.9.1 Chlorine 549

16.9.2 Chloramines 549

16.9.3 Chlorine Dioxide 550

16.9.4 Peracids 550

16.9.5 Ozone 550

16.9.6 Ultraviolet 551

16.9.7 Comparative Risks 551

16.10 Disinfection to Combat Invasive Species 551

Questions and Problems 553

References 556

Section V: Biological Wastewater Treatment 565

17 Aerobic Biological Treatment: Biotreatment Processes 567

17.1 Microorganisms in Aerobic Biological Treatment 567

17.2 The Activated Sludge Process 568

17.3 Substrate Removal and Growth of Microorganisms 569

17.3.1 Substrate Removal 569

Temperature Dependence of Rate Coefficients 571

BOD, COD, and TOC Removal 571

17.3.2 Growth of Microorganisms and Biological Sludge Production 572

Sludge Composition and Nutrient Requirements 573

17.4 Activated Sludge Configurations 574

17.4.1 Definition of Symbols for the Activated Sludge Process Models 575

17.4.2 Reactor 577

17.4.3 System Effluent and Waste Sludge Line 577

17.4.4 Clarifier 577

17.5 Process Analysis 578

17.5.1 Physical Concentration of Solids in the Bioreactor 578

17.5.2 Solids Retention Time 580

17.5.3 Sludge Volume Index 580

17.5.4 CM Reactor Without Recycle 582

Substrate Balance 582

Biomass Balance 583

17.5.5 CM Reactor with Recycle 585

Biomass Balance 585

17.5.6 Application of the Basic Model in the Historical Context 586

Frailties of the Historical Models 590

17.5.7 Matrix Representation of the Basic (Soluble Substrate) Model 591

17.5.8 The Rate of Recycle 593

17.5.9 Food-to-Microorganism Ratio and SRT 594

17.6 Advanced Model for Carbon Removal 596

17.6.1 Total Effluent COD from the Process 599

17.6.2 Removal of Influent Particulate Organic Matter 599

17.6.3 Estimation of Parameters and Calibration of the Advanced Model 600

17.6.4 Calibration of Models to Existing Data 602

17.7 Sludge Production in Activated Sludge Systems 604

17.8 Plug Flow Activated Sludge Treatment 607

17.9 Variations of the Activated Sludge Process 609

17.9.1 Sequencing Batch Reactors 609

17.9.2 Extended Aeration 612

17.10 Other Activated Sludge Process Variations 613

17.10.1 Pure Oxygen Activated Sludge Process 615

17.10.2 Powdered Activated Carbon Activated Sludge Process 615

Design Parameters and Operating Conditions for Activated Sludge Processes 615

17.11 Design of Activated Sludge Processes for Nitrogen and Phosphorus Removal 616

17.11.1 Nitrogen Transformations 616

Nitrogen Removal–Denitrification 621

17.11.2 Advanced Denitrification Processes 626

SHARON Process 626

Anammox Process 627

Other Processes 628

17.11.3 Enhanced Phosphorus Uptake 628

Fermentation of Primary or Activated Sludge 630

Phostrip and Bardenpho Bio-P Processes 632

17.12 Operating Characteristics of Activated Sludge Processes 632

17.12.1 SRT and Characteristics of Waste Activated Sludge 632

17.13 Granular Activated Sludge and Membrane Processes 634

17.13.1 Granular Activated Sludge Processes 634

17.13.2 Membrane Activated Sludge Processes 635

Design of Submerged Membrane Reactors 637

17.14 Fixed-Film Activated Sludge Processes 639

17.14.1 Integrated Fixed-Film Activated Sludge and Moving Bed Bioreactor Processes 639

Design of MBBRs 641

17.14.2 Biologically Activated Filters 645

Design of Biological Active Filters 647

17.14.3 Rotating Biological Contact Units 648

17.15 Fixed-Film Trickling Filter Processes 650

17.15.1 Trickling Filters 650

Sludge Production from Trickling Filters 656

Air Supply in Trickling Filters 656

Operation of Trickling Filters 660

17.15.2 Hydraulic Design of Distributors for Trickling Filters 660

17.16 Oxygen Uptake in Activated Sludge Processes 663

17.17 Metals Removal in Activated Sludge Processes 664

17.18 Aerobic Sludge Digestion 664

17.18.1 Model for Aerobic Sludge Digestion 665

Oxygen Uptake in Aerobic Digestion 668

Rate Constants and Sludge Degradability 668

17.18.2 Thermophilic Aerobic Digestion 669

Pre-treatment for Aerobic Sludge Digestion 672

17.18.3 Indicator Microorganism Reduction in Aerobic Digestion 672

Questions and Problems 673

References 680

18 Aerobic Biological Treatment: Other Process Operations 689

18.1 Aeration in Biological Wastewater Treatment 689

18.1.1 Aeration Devices in Wastewater Treatment 692

Diffused Aerators 692

Surface and Other Aerators 692

18.2 Post-aeration Systems for Wastewater Treatment 697

18.2.1 Diffused Aeration Systems 697

18.2.2 Cascades 699

18.2.3 Weirs 699

18.3 Type III Sedimentation: Zone Settling 700

18.3.1 Design of a Basin for Type III Sedimentation 703

Gravity Flux 703

Underflow Flux 704

18.3.2 Secondary Clarifier Design 708

18.3.3 Modeling for Secondary Clarifier and Operation 709

18.3.4 Membrane Separation of Solids 711

Lamella Clarifiers 712

18.4 Sludge Settling Problems and Foaming 712

18.4.1 Microorganisms 712

18.4.2 Selectors and Process Operating Conditions 713

Questions and Problems 715

References 718

19 Anaerobic Wastewater Treatment 721

History 721

19.1 Anaerobic Metabolism 722

19.1.1 Hydrolysis 722

19.1.2 Acid Formation: Acidogenesis and Acetogenesis 723

19.1.3 Methanogenesis 724

19.1.4 Other Metabolic Pathways 725

19.1.5 Environmental Variables 725

Oxidation–Reduction Potential 725

Temperature 725

pH 725

Mixing 726

Ammonia and Sulfide Control 726

Nutrient Requirements 727

19.2 Process Fundamentals 727

19.2.1 Solids Yield and Retention Time 727

19.2.2 Biogas Potential 729

Biochemical Methane Potential and Anaerobic Toxicity Assay 729

Methane Production in Anaerobic Treatment 730

Dissolved Methane 731

Biogas Utilization 732

19.3 Process Analysis 732

19.3.1 Definition of Symbols for the Anaerobic Models 733

19.3.2 General Model for an Anaerobic Process 734

Anaerobic Reactor Receiving Only Particulate Substrate 734

Anaerobic Reactor Receiving Only Soluble Substrate 737

The Traditional Digester Sizing Equation for Anaerobic Sludge Digesters 737

19.3.3 Advanced Model for an Anaerobic Process 740

Substrate Removal and Biomass Accumulation 741

Temperature Effects on Rate Coefficients 747

19.4 Misconceptions and Barriers about Anaerobic Treatment 747

19.5 Anaerobic Treatment Processes 750

19.5.1 Conventional Anaerobic Treatment 750

19.5.2 Contact Process 753

19.5.3 Upflow Anaerobic Sludge Blanket Reactor 754

19.5.4 Fixed-Film Reactors 756

Upflow Fixed-Film Reactors 757

Downflow Fixed-Film Reactors 758

Fluidized Bed Reactors 759

19.5.5 Two-Phase Anaerobic Digestion 759

19.5.6 Thermophilic Digestion 760

19.5.7 Membrane Anaerobic Treatment 760

19.5.8 Pre-treatment of Sludge for Anaerobic Digestion of Biosolids 760

19.6 Anaerobic Digestion of Municipal Solid Waste 762

19.7 Process Stability and Monitoring 763

19.7.1 Chemical Precipitation Problems in Anaerobic Digesters 764

19.7.2 Recovery of Nutrients through Struvite Harvesting 764

19.7.3 Sludge Production 766

19.7.4 Anaerobic Treatment of Low-Strength Wastes 766

19.8 Comparison of Anaerobic and Aerobic Treatment Processes 767

19.8.1 Pollutant Removal Efficiency 768

19.8.2 Number and Size of Operations 768

19.8.3 Energy and Chemical Inputs 769

19.8.4 Heat Exchanger 770

19.9 Energy Assessment of Anaerobic and Aerobic Treatment 774

Anaerobic Versus Aerobic Treatment 776

Calculation of the Energy Potential of a Waste 777

19.10 Pathogen Reduction in Anaerobic Processes 777

Questions and Problems 778

References 781

20 Treatment in Ponds and Land Systems 789

20.1 Overview of Stabilization Ponds 789

20.1.1 Pond Operation 790

20.1.2 Pond Effluent Quality 791

20.2 Pond Types 792

20.3 Design of Pond Systems 795

20.3.1 Design of Ponds in the Far North 796

20.3.2 Models for Facultative Ponds 798

20.3.3 Nitrogen and Phosphorus Removal 798

20.3.4 Heat Balance for Ponds 799

20.4 Removal of Suspended Solids from Pond Effluents 800

20.5 Indicator Microorganism Die-off in Ponds 801

20.6 Aerated Lagoons 802

20.7 Treatment of Wastewater in Land Systems 804

20.7.1 Land Treatment of Wastewater 804

Measurement of Hydraulic Conductivity 805

Wastewater Constituents Influencing Land Treatment 807

20.7.2 Slow Rate Land Application Systems 807

20.7.3 Soil Aquifer Treatment 814

20.7.4 Overland Flow Systems 815

Questions and Problems 817

References 819

Section VI: Final Disposal and Impact Analysis 823

21 Sludge Processing and Land Application 825

21.1 Sludge Characteristics and Conditioning 825

Sludge Density 825

Sludge Viscosity 827

21.2 Sludge Generation and Treatment Processes 828

21.3 Sludge Conditioning 833

21.4 Sludge Thickening 836

21.4.1 Gravity Thickening 836

21.4.2 Flotation Thickening 837

21.5 Mechanical Sludge Dewatering 839

21.5.1 Centrifugation 840

21.5.2 Vacuum Dewatering 843

21.5.3 Plate Pressure Filters 846

21.6 Land Application of Sludge 847

Questions and Problems 854

References 856

22 Effluent Disposal in Natural Waters 859

22.1 Pollutants in Natural Waters 859

22.1.1 Water Quality Indices 859

Fish Survival and Temperature 862

Nutrient Loadings to Lakes 864

22.2 Loading Equations for Streams 865

22.2.1 Pollutant Decay in Streams 865

22.2.2 Conservative Substance 866

Point Source 866

Distributed Source 866

22.2.3 Substances That Are Transformed by One Reaction 866

Point Source 866

Distributed Source 867

22.3 Dissolved Oxygen Variation in a Stream 870

22.3.1 Nitrification in Natural Waters 873

22.3.2 Factors Affecting the Dissolved Oxygen Sag Curve 874

22.3.3 The Reaeration Rate Coefficient 877

22.3.4 Reaeration at Dams 878

22.4 Combined Sewer Overflows Abatement 878

Questions and Problems 881

References 883

23 Life Cycle Analysis 887

23.1 Historical Development of LCA 888

23.2 Why Use LCA; What Are the Objectives; What Are Its Benefits and What Does It Not Do? 888

23.3 ISO Standards 14040 and 14044 889

23.4 Definitions of Terms in ISO 14040 and 14044 889

23.5 Principles Established by ISO 14040 890

23.6 Key Components of the ISO Standards 891

23.6.1 Goal and Scope 892

23.6.2 System Boundaries 892

Life Cycle Inventory Analysis 893

23.6.3 Life Cycle Impact Assessment 894

Selection of Impact Categories, Category Indicators, and Characterization Models 894

Assignment of LCI Results to the Selected Impact Categories (Classification) 895

Calculation of Category Indicator Results (Characterization) 895

Characterization Factors, Midpoints and Endpoints 896

Optional Elements of the LCIA 897

23.6.4 Limitations of LCIA 898

23.6.5 Interpretation 898

23.7 Software and Databases 899

23.8 Examples of Case Studies of LCA in Water and Wastewater Treatment Projects 899

Questions and Problems 906

References 909

Appendix A 913

Author Index 927

Subject Index 937

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Theory and Practice of Water and Wastewater Treatment

Theory and Practice of Water and Wastewater Treatment

1119312361

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