Ronald L. Droste, Ronald L. Gehr

Theory and Practice of Water and Wastewater Treatment (eBook, ePUB)

• Format: ePub

Produktbeschreibung

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.

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Produktdetails

• Verlag: John Wiley & Sons
• Seitenzahl: 992
• Erscheinungstermin: 31. Juli 2018
• Englisch
• ISBN-13: 9781119312383
• Artikelnr.: 53698992

Autorenporträt

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).

Inhaltsangabe

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