1 Wastewater Engineering:An Overview 1
1-1 Terminology 3
1-2 Impact of Regulations on Wastewater Engineering 3
1-3 Health and Environmental Concerns in Wastewater Management 7
1-4 Wastewater Characteristics 9
Improved Analytical Techniques 10
Importance of Improved Wastewater Characterization 10
1-5 Wastewater Treatment 10
Treatment Methods 11
Current Status 12
New Directions and Concerns 15
1-6 Wastewater Reclamation and Reuse 20
Future Trends in Wastewater Treatment 20
Current Status 21
New Directions and Concerns 21
Future Trends in Technology 21
1-7 Biosolids and Residuals Management 22
Current Status 22
New Directions and Concerns 23
Future Trends in Biosolids Processing 23
2 Constituents in Wastewater 27
Sampling 29
2-2 Sampling and Analytical Procedures 29
Constituents of Concern in Wastewater Treatment 29
Constituents Found in Wastewater 29
2-1 Wastewater Constituents 29
Methods of Analysis 34
Units of Measurement for Physical and Chemical Parameters 35
Useful Chemical Relationships 35
2-3 Physical Characteristics 42
Solids 42
Particle Size Distribution 48
Turbidity 51
Color 52
Absorption/Transmittance 52
Temperature 54
Conductivity 56
Density, Specific Gravity, and Specific Weight 56
2-4 Inorganic Nonmetallic Constituents 57
pH 57
Chlorides 59
Alkalinity 59
Nitrogen 60
Phosphorus 63
Sulfur 64
Gases 64
Odors 70
Sampling and Methods of Analysis 77
Sources of Metals 77
Importance of Metals 77
2-5 Metallic Constituents 77
Typical Effluent Discharge Limits for Metals 78
2-6 Aggregate Organic Constituents 80
Measurement of Organic Content 81
Biochemical Oxygen Demand(BOD) 81
Total and Soluble Chemical Oxygen Demand(COD and SCOD) 93
Total and Dissolved Organic Carbon(TOC and DTOC) 94
UV-Absorbing Organic Constituents 95
Theoretical Oxygen Demand(ThOD) 96
Interrelationships between BOD, COD,and TOC 96
Surfactants 98
Oil and Grease 98
2-7 Individual Organic Compounds 99
Priority Pollutants 99
Analysis of Individual Organic Compounds 100
Volatile Organic Compounds(VOCs) 100
Disinfection Byproducts 102
Pesticides and Agricultural Chemicals 102
Emerging Organic Compounds 102
2-8 Biological Characteristics 104
Microorganisms Found in Surface Waters and Wastewater 104
Pathogenic Organisms 109
Use of Indicator Organisms 115
Enumeration and Identification of Bacteria 118
Enumeration and Identification of Viruses 126
Polymerase Chain Reaction (PCR) 129
Development of Microorganisms Typing Techniques 130
New and Reemerging Microorganisms 130
2-9 Toxicity Tests 130
Toxicity Terminology 131
Toxicity Testing 133
Analysis of Toxicity Test Results 134
Application of Toxicity Test Results 136
Identification of Toxicity Components 137
3 Analysis and Selection of Wastewater Flowrates and Constituent Loadings 153
3-1 Components of Wastewater Flows 154
3-2 Wastewater Sources and Flowrates 154
Domestic Wastewater Sources and Flowrates 155
Strategies for Reducing Interior Water Use and Wastewater Flowrates 158
Water Use in Developing Countries 162
Sources and Rates of Industrial(Nondomestic)Wastewater Flows 162
Infiltration/Inflow 163
Exfiltration from Collection Systems 167
Combined System Flowrates 168
3-3 Statistical Analysis of Flowrates,Constituent Concentrations, and Mass Loadings 170
Common Statistical Parameters 170
Graphical Analysis of Data 171
3-4 Analysis of Wastewater Flowrate Data 178
Definition of Terms 178
Variations in Wastewater Flowrates 179
Wastewater Flowrate Factors 180
Wastewater Constituent Concentrations 181
3-5 Analysis of Constituent Mass Loading Data 181
Variations in Constituent Concentrations 185
Flow-Weighted Constituent Concentrations 192
Calculation of Mass Loadings 194
Effect of Mass Loading Variability on Treatment Plant Performance 197
3-6 Selection of Design Flowrates and Mass Loadings 197
Design Flowrates 199
Design Mass Loadings 205
4 Introduction to Process Analysis and Selection 215
4-1 Reactors Used for the Treatment of Wastewater 218
Types of Reactors 218
Hydraulic Characteristics of Reactors 220
Application of Reactors 220
4-2 Mass-Balance Analysis 222
The Mass-Balance Principle 222
Preparation of Mass Balances 224
Application of the Mass-Balance Analysis 224
Steady-State Simplification 225
4-3 Modeling Ideal Flow in Reactors 226
Ideal Flow in Complete-Mix Reactor 226
Ideal Flow in Plug-Flow Reactor 227
4-4 Analysis of Nonideal Flow in Reactors Using Tracers 229
Factors Leading to Nonideal Flow in Reactors 229
Conduct of Tracer Tests 231
Types of Tracers 231
Need for Tracer Analysis 231
Analysis of Tracer Response Curves 233
Practical Interpretation of Tracer Measurements 242
4-5 Modeling Nonideal Flow in Reactors 245
The Distinction between Molecular Diffusion, Turbulent Diffusion, and Dispersion 245
Plug-Flow Reactor with Axial Dispersion 246
Complete-Mix Reactors in Series 252
4-6 Reactions, Reaction Rates, and Reaction Rate Coefficients 257
Types of Reactions 257
Rate of Reaction 258
Reaction Order 259
Types of Rate Expressions 260
Effects of Temperature on Reaction Rate Coefficients 261
Rate Expressions Used in Environmental Modeling 261
Analysis of Reaction Rate Coefficients 264
4-7 Modeling Treatment Process Kinetics 269
Batch Reactor with Reaction 269
Complete-Mix Reactor with Reaction 270
Complete-Mix Reactors in Series with Reaction 271
Ideal Plug-Flow Reactor with Reaction 274
Comparison of Complete-Mix and Plug-Flow Reactors with Reaction 275
Ideal Plug-Flow Reactor with Retarded Reaction 277
Plug-Flow Reactor with Axial Dispersion and Reaction 279
Other Reactor Flow Regimes and Reactor Combinations 281
Basic Principle of Mass Transfer 283
4-8 Treatment Processes Involving Mass Transfer 283
Gas-Liquid Mass Transfer 284
Liquid-Solid Mass Transfer 293
4-9 Introduction to Process Selection 297
Important Factors in Process Selection 297
Process Selection Based on Reaction Kinetics 299
Process Selection Based on Mass Transfer 300
Process Design Based on Loading Criteria 301
Bench Tests and Pilot-Plant Studies 301
Reliability Considerations in Process Selection 301
5 Physical Unit Operations 311
Classification of Screens 315
5-1 Screening 315
Coarse Screens(Bar Racks) 316
Fine Screens 322
Microscreens 326
Screenings Characteristics and Quantities 327
5-2 Coarse Solids Reduction 330
Comminutors 331
Macerators 332
Grinders 333
Design Considerations 333
5-3 Flow Equalization 333
Description/Application 333
Design Considerations 335
5-4 Mixing and Flocculation 344
Continuous Rapid Mixing in Wastewater Treatment 345
Continuous Mixing in Wastewater Treatment 345
Energy Dissipation in Mixing and Flocculation 347
Timescale in Mixing 350
Types of Mixers Used for Rapid Mixing in Wastewater Treatment 350
Types of Mixers Used for Flocculation in Wastewater Treatment 355
Types of Mixers Used for Continuous Mixing in Wastewater Treatment 359
New Developments in Mixing Technology 361
5-5 Gravity Separation Theory 361
Description 362
Particle Settling Theory 363
Discrete Particle Settling 367
Flocculent Particle Settling 372
Inclined Plate and Tube Settling 374
Hindered(Zone)Settling 378
Compression Settling 383
Gravity Separation in an Accelerated Flow Field 383
5-6 Grit Removal 384
Types of Grit Chambers 385
Horizontal-Flow Grit Chambers 385
Aerated Grit Chambers 386
Vortex-Type Grit Chambers 392
Solids(Sludge)Degritting 392
Grit Characteristics, Quantities,Processing, and Disposal 394
5-7 Primary Sedimentation 396
Description 397
Sedimentation Tank Performance 405
Design Considerations 406
Characteristics and Quantities of Solids(Sludge)and Scum 411
5-8 High-Rate Clarification 411
Enhanced Particle Flocculation 412
Analysis of Ballasted Particle Flocculation and Settling 412
Process Application 414
5-9 Large-Scale Swirl and Vortex Separators for Combined Wastewater and Stormwater 417
5-10 Flotation 419
Description 419
Design Considerations for Dissolved-Air Flotation Systems 422
5-11 Oxygen Transfer 425
Description 425
Evaluation of Oxygen Transfer Coefficient 425
5-12 Aeration Systems 430
Types of Aeration Systems 430
Diffused-Air Aeration 430
Mechanical Aerators 443
Energy Requirement for Mixing in Aeration Systems 448
Generation and Dissolution of High-Purity Oxygen 448
Postaeration 452
5-13 Removal of Volatile Organic Compounds(VOCs)by Aeration 456
Emission of VOCs 456
Mass Transfer Rates for VOCs 457
Mass Transfer of VOCs from Surface and Diffused-Air Aeration Processes 459
Control Strategies for VOCs 463
6 Chemical Unit Processes 475
6-1 Role of Chemical Unit Processes in Wastewater Treatment 476
Application of Chemical Unit Processes 477
Considerations in the Use of Chemical Unit Processes 478
6-2 Fundamentals of Chemical Coagulation 478
Basic Definitions 479
Nature of Particles in Wastewater 480
Development and Measurement of Surface Charge 481
Particle-Particle Interactions 482
Particle Destabilization with Potential-Determining Ions and Electrolytes 483
Particle Destabilization and Aggregation with Polyelectrolytes 485
Particle Destabilization and Removal with Hydrolyzed Metal Ions 486
6-3 Chemical Precipitation for Improved Plant Performance 493
Chemical Reactions in Wastewater Precipitation Applications 493
Enhanced Removal of Suspended Solids in Primary Sedimentation 497
Independent Physical-Chemical Treatment 498
Estimation of Sludge Quantities from Chemical Precipitation 499
6-4 Chemical Precipitation for Phosphorus Removal 500
Chemistry of Phosphate Precipitation 501
Strategies for Phosphorus Removal 503
Phosphorus Removal Using Metal Salts and Polymers 505
Phosphorus Removal Using Lime 507
Comparison of Chemical Phosphorus Removal Processes 508
Phosphorus Removal with Effluent Filtration 508
Estimation of Sludge Quantities from Phosphorus Precipitation 509
6-5 Chemical Precipitation for Removal of Heavy Metals and Dissolved Inorganic Substances 514
Precipitation Reactions 514
Coprecipitation with Phosphorus 517
6-6 Chemical Oxidation 517
Fundamentals of Chemical Oxidation 517
Applications 522
Chemical Oxidation of BOD and COD 523
Chemical Oxidation of Ammonia 524
pH Adjustment 526
6-7 Chemical Neutralization, Scale Control,and Stabilization 526
Analysis of Scaling Potential 528
Scaling Control 532
Stabilization 532
6-8 Chemical Storage, Feeding, Piping,and Control Systems 532
Chemical Storage and Handling 533
Dry Chemical-Feed Systems 533
Liquid Chemical-Feed Systems 536
Gas Chemical-Feed Systems 537
Initial Chemical Mixing 540
7 Fundamentals of Biological Treatment 545
7-1 Overview of Biological Wastewater Treatment 547
Some Useful Definitions 548
Role of Microorganisms in Wastewater Treatment 548
Objectives of Biological Treatment 548
Types of Biological Processes for Wastewater Treatment 551
7-2 Composition and Classification of Microorganisms 555
Cell Components 555
Cell Composition 557
Environmental Factors 558
Microorganism Identification and Classification 559
Use of Molecular Tools 561
7-3 Introduction to Microbial Metabolism 563
Carbon and Energy Sources for Microbial Growth 563
Nutrient and Growth Factor Requirements 565
7-4 Bacterial Growth and Energetics 565
Bacterial Growth Patterns in a Batch Reactor 566
Bacterial Reproduction 566
Bacterial Growth and Biomass Yield 567
Measuring Biomass Growth 567
Estimating Biomass Yield and Oxygen Requirements from Stoichiometry 568
Estimating Biomass Yield from Bioenergetics 571
Stoichiometry of Biological Reactions 578
Biomass Synthesis Yields for Different Growth Conditions 579
Observed versus Synthesis Yield 580
7-5 Microbial Growth Kinetics 580
Microbial Growth Kinetics Terminology 581
Rate of Utilization of Soluble Substrates 581
Other Rate Expressions for the Utilization of Soluble Substrate 582
Rate of Soluble Substrate Production from Biodegradable Particulate Organic Matter 583
Kinetic Coefficients for Substrate Utilization and Biomass Growth 584
Rate of Biomass Growth with Soluble Substrates 584
Rate of Oxygen Uptake 585
Effects of Temperature 585
Total Volatile Suspended Solids and Active Biomass 586
Net Biomass Yield and Observed Yield 587
7-6 Modeling Suspended Growth Treatment Processes 588
Description of Suspended Growth Treatment Processes 589
Biomass Mass Balance 589
Substrate Mass Balance 592
Mixed Liquor Solids Concentration and Solids Production 592
Oxygen Requirements 595
The Observed Yield 595
Design and Operating Parameters 598
Process Performance and Stability 600
Modeling Plug-Flow Reactors 601
7-7 Substrate Removal in Attached Growth Treatment Processes 602
Substrate Flux in Biofilms 604
Substrate Mass Balance for Biofilm 605
Substrate Flux Limitations 606
7-8 Aerobic Biological Oxidation 607
Process Description 608
Microbiology 608
Stoichiometry of Aerobic Biological Oxidation 609
Environmental Factors 610
Growth Kinetics 610
7-9 Biological Nitrification 611
Process Description 611
Microbiology 611
Stoichiometry of Biological Nitrification 612
Growth Kinetics 614
Environmental Factors 615
7-10 Biological Denitrification 616
Process Description 616
Microbiology 618
Stoichiometry of Biological Denitrification 619
Growth Kinetics 621
7-11 Biological Phosphorus Removal 623
Environmental Factors 623
Process Description 624
Microbiology 625
Stoichiometry of Biological Phosphorus Removal 627
Growth Kinetics 629
Environmental Factors 629
7-12 Anaerobic Fermentation and Oxidation 629
Process Description 630
Microbiology 631
Stoichiometry of Anaerobic Fermentation and Oxidation 633
Growth Kinetics 634
7-13 Biological Removal of Toxic and Recalcitrant Organic Compounds 635
Development of Biological Treatment Methods 635
Environmental Factors 635
Anaerobic Degradation 637
Aerobic Biodegradation 638
Abiotic Losses 638
Modeling Biotic and Abiotic Losses 640
7-14 Biological Removal of Heavy Metals 644
8 Suspended Growth Biological Treatment Processes 659
8-1 Introduction to the Activated-Sludge Process 661
Historical Development 661
Description of Basic Process 661
Evolution of the Activated-Sludge Process 663
Recent Process Developments 664
Key Wastewater Constituents for Process Design 666
8-2 Wastewater Characterization 666
Measurement Methods for Wastewater Characterization 671
Recycle Flows and Loadings 676
8-3 Fundamentals of Process Analysis and Control 676
Process Design Considerations 677
Process Control 689
Operational Problems 694
Activated-Sludge Selector Processes 700
8-4 Processes for BOD Removal and Nitrification 703
Process Design Considerations 704
Complete-Mix Activated-Sludge Process 705
Sequencing Batch Reactor Process 720
Staged Activated-Sludge Process 734
Alternative Processes for BOD Removal and Nitrification 738
Process Design Parameters 740
Process Selection Considerations 740
8-5 Processes for Biological Nitrogen Removal 749
Overview of Biological Nitrogen-Removal Processes 750
Single-Sludge Biological Nitrogen-Removal Processes 750
Process Design Considerations 753
Anoxic/Aerobic Process Design 761
Step-Feed Anoxic/Aerobic Process Design 765
Intermittent Aeration Process Design 776
Postanoxic Endogenous Denitrification 780
Sequencing Batch Reactor Process Analysis 781
Postanoxic Denitrification with an External Carbon Source 784
Nitrogen Removal in Anaerobic Digestion Recycle Streams 788
Alternative Process Configurations for Biological Nitrogen Removal 789
Process Design Parameters 789
Process Selection Considerations 789
8-6 Processes for Biological Phosphorus Removal 799
Biological Phosphorus-Removal Processes 799
Process Design Considerations 801
Process Control 804
Solids Separation Facilities 805
Methods to Improve Phosphorus-Removal Efficiency in BPR Systems 805
Biological Phosphorus-Removal Process Performance 807
Process Design Parameters 809
Process Selection Considerations 809
Alternative Processes for Biological Phosphorous Removal 809
8-7 Selection and Design of Physical Facilities for Activated-Sludge Processes 816
Aeration System 816
Aeration Tanks and Appurtenances 816
Solids Separation 820
Design of Solids Separation Facilities 833
8-8 Suspended Growth Aerated Lagoons 840
Types of Suspended Growth Aerated Lagoons 841
Process Design Considerations for Flow-Through Lagoons 843
Dual-Powered Flow-Through Lagoon System 853
8-9 Biological Treatment with Membrane Separation 854
Overview of Membrane Biological Reactors 854
Process Description 855
Membrane Fouling Control 857
Process Capabilities 858
8-10 Simulation Design Models 859
Model Matrix Format, Components,and Reactions 860
Model Applications 861
9 Attached Growth and Combined Biological Treatment Processes 888
9-1 Background 888
Evolution of Attached Growth Processes 888
Mass Transfer Limitations 890
9-2 Trickling Filters 890
Trickling Filter Classification and Applications 893
Design of Physical Facilities 896
Process Design Considerations 909
Nitrification Design 922
9-3 Rotating Biological Contactors 930
Process Design Considerations 932
Physical Facilities for RBC Process 935
RBC Process Design 937
9-4 Combined Aerobic Treatment Processes 940
Trickling Filter/Solids Contact and Trickling Filter/Activated-Sludge Processes 940
Activated Biofilter and Biofilter Activated-Sludge Processes 943
Series Trickling Filter-Activated-Sludge Process 944
Design Considerations for Combined Trickling Filter Activated-Sludge Systems 944
9-5 Activated Sludge with Fixed-Film Packing 952
Processes with Internal Suspended Packing for Attached Growth 952
Processes with Internal Fixed Packing for Attached Growth 955
9-6 Submerged Attached Growth Processes 957
Downflow Submerged Attached Growth Processes 957
Upflow Submerged Attached Growth Processes 959
Fluidized-Bed Bioreactors(FBBR) 961
9-7 Attached Growth Denitrification Processes 962
Downflow Packed-Bed Postanoxic Denitrification Processes 962
Upflow Packed-Bed Postanoxic Denitrification Reactors 967
Fluidized-Bed Reactors for Postanoxic Denitrification 967
Submerged Rotating Biological Contactors 969
Attached Growth Preanoxic Denitrification Processes 969
10 Anaerobic Suspended and Attached Growth Biological Treatment Processes 983
Advantages of Anaerobic Treatment Processes 984
10-1 The Rationale for Anaerobic Treatment 984
Summary Assessment 986
10-2 General Design Considerations for Anaerobic Treatment Processes 986
Disadvantages of Anaerobic Treatment Processes 986
Characteristics of the Wastewater 987
Solids Retention Time 991
Expected Methane Gas Production 992
Treatment Efficiency Needed 994
Sulfide Production 994
Ammonia Toxicity 995
Liquid-Solids Separation 996
10-3 Anaerobic Suspended Growth Processes 996
Anaerobic Contact Process 997
Complete-Mix Process 997
Anaerobic Sequencing Batch Reactor 999
Design of Anaerobic Suspended Growth Processes 999
10-4 Anaerobic Sludge Blanket Processes 1005
Upflow Sludge Blanket Reactor Process 1005
Design Considerations for UASB Process 1007
Anaerobic Baffled Reactor 1016
Anaerobic Migrating Blanket Reactor 1017
10-5 Attached Growth Anaerobic Processes 1018
Upflow Packed-Bed Attached Growth Reactor 1019
Upflow Attached Growth Anaerobic Expanded-Bed Reactor 1020
Attached Growth Anaerobic Fluidized-Bed Reactor 1020
Downflow Attached Growth Processes 1022
10-6 Other Anaerobic Treatment Processes 1024
Covered Anaerobic Lagoon Process 1024
Membrane Separation Anaerobic Treatment Process 1026
11 Advanced Wastewater Treatment 1035
11-1 Need for Advanced Wastewater Treatment 1037
11-2 Technologies Used for Advanced Treatment 1038
Residual Constituents in Treated Wastewater 1038
Classification of Technologies 1038
Removal of Organic and Inorganic Colloidal and Suspended Solids 1038
Removal of Dissolved Organic Constituents 1040
Removal of Dissolved Inorganic Constituents 1041
Removal of Biological Constituents 1043
Process Selection and Performance Data 1044
11-3 Introduction to Depth Filtration 1044
Description of the Filtration Process 1044
Filter Hydraulics 1050
Analysis of the Filtration Process 1057
11-4 Selection and Design Considerations for Depth Filters 1069
Available Filtration Technologies 1069
Performance of Different Types of Filter Technologies 1078
Issues Related to Design and Operation of Treatment Facilities 1080
Importance of Influent Wastewater Characteristics 1081
Selection of Filtration Technology 1081
Filter-Bed Characteristics 1084
Filter Flowrate Control 1089
Filter Backwashing Systems 1091
Filter Appurtenances 1093
Filter Instrumentation and Control Systems 1093
Effluent Filtration with Chemical Addition 1095
Filter Problems 1096
Need for Pilot-Plant Studies 1096
11-5 Surface Filtration 1098
Discfilter? 1098
Cloth-Media Disk Filter? 1100
Performance Characteristics 1103
Membrane Process Classification 1104
Membrane Process Terminology 1104
11-6 Membrane Filtration Processes 1104
Membrane Configurations 1108
Membrane Operation 1111
Membrane Fouling 1117
Application of Membranes 1121
Electrodialysis 1131
Pilot Studies for Membrane Applications 1134
Disposal of Concentrated Waste Streams 1135
11-7 Adsorption 1138
Types of Adsorbents 1138
Fundamentals of Adsorption 1140
Activated Carbon Adsorption Kinetics 1146
Activated Carbon Treatment Process Applications 1149
Analysis and Design of Granular Activated Carbon Contactor 1152
Small-Scale Column Tests 1156
Analysis and Design of Powdered Activated Carbon Contactor 1159
Activated Sludge with Powdered Activated Carbon Treatment 1161
11-8 Gas Stripping 1162
Analysis of Gas Stripping 1163
Design of Stripping Towers 1174
Application 1178
11-9 Ion Exchange 1180
Ion-Exchange Materials 1181
Typical Ion-Exchange Reactions 1182
Exchange Capacity of Ion-Exchange Resins 1183
Ion-Exchange Chemistry 1185
Application of Ion Exchange 1189
Operational Considerations 1196
11-10 Advanced Oxidation Processes 1196
Theory of Advanced Oxidation 1196
Technologies Used to Produce Hydroxyl Radicals (HO ) 1197
Applications 1200
Operational Problems 1202
11-11 Distillation 1202
Distillation Processes 1202
Disposal of Concentrated Waste 1205
12 Disinfection Processes 1217
12-2 Disinfection Theory 1219
12-1 Regulatory Requirements for Wastewater Disinfection 1219
Characteristics of an Ideal Disinfectant 1220
Disinfection Methods and Means 1220
Mechanisms of Disinfectants 1223
Factors Influencing the Action of Disinfectants 1223
12-3 Disinfection with Chlorine 1231
Characteristics of Chlorine Compounds 1231
Chemistry of Chlorine Compounds 1234
Breakpoint Reaction with Chlorine 1237
Measurement and Reporting of Disinfection Process Variables 1241
Germicidal Efficiency of Chlorine and Various Chlorine Compounds 1242
Factors That Affect Disinfection Efficiency of Chlorine 1244
Modeling the Chlorine Disinfection Process 1248
Review of the CRt Concept 1252
Required Chlorine Dosage for Disinfection 1252
Formation and Control of Disnfection Byproducts 1255
Environmental Impacts 1257
12-4 Disinfection with Chlorine Dioxide 1258
Characteristics of Chlorine Dioxide 1258
Chlorine Dioxide Chemistry 1259
Effectiveness of Chlorine Dioxide as a Disinfectam 1259
Byproduct Formation and Control 1260
Need Jot Dechlorination 1261
Dechlorination of Wastewater Treated with Chlorine and Chlorine Compounds 1261
12-5 Dechlorination 1261
Environmental Impacts 1261
Dechlorination of Chlorine Dioxide with Sulfur Dioxide 1264
12-6 Design of Chlorination and Dechlorination Facilities 1264
Sizing Chlorination Facilities 1264
Application Flow Diagrams 1266
Dosage Control 1269
Injection and Initial Mixing 1270
Chlorine Contact Basin Design 1270
Chlorine Residual Measurement 1283
Chlorine Storage Facilities 1284
Chlorine Containment Facilities 1284
12-7 Disinfection with Ozone 1286
Dechlorination Facilities 1286
Ozone Properties 1287
Ozone Chemistry 1287
Ozone Disinfection Systems Components 1288
Effectiveness of Ozone as a Disinfectant 1290
Modeling the Ozone Disinfection Process 1290
Required Ozone Dosages for Disinfection 1293
Byproduct Formation and Control 1293
Environmental Impacts of Using Ozone 1295
Other Benefits of Using Ozone 1295
12-8 Other Chemical Disinfection Methods 1295
Peracetic Acid 1295
Ozone/Hydrogen Peroxide(Peroxone) 1297
Combined Chemical Disinfection Processes 1297
Source of UV Radiation 1298
12-9 Ultraviolet(UV)Radiation Disinfection 1298
UV Disinfection System Components and Configurations 1301
Germicidal Effectiveness of UV Radiation 1304
Modeling the UV Disinfection Process 1309
Estimating UV Dose 1311
Ultraviolet Disinfection Guidelines 1316
Selection and Sizing of a UV Disinfection System 1324
Troubleshooting UV Disinfection Systems 1326
Environmental Impacts of UV Radiation Disinfection 1329
2-10 Comparison of Alternative Disinfection Technologies 1329
Germicidal Effectiveness 1330
Advantages and Disadvantages 1330
13 Water Reuse 1345
13-1 Wastewater Reclamation and Reuse:An Introduction 1347
Definition of Terms 1347
The Role of Water Recycling in the Hydrologic Cycle 1347
Historical Perspective 1349
Wastewater Reuse Applications 1351
Need for Water Reuse 1354
13-2 Public Health and Environmental Issues in Water Reuse 1356
Constituents in Reclaimed Water 1356
Public Health Issues 1358
Environmental Issues 1358
The Evolution of Water Reuse Guidelines in the United States 1358
Water Reclamation Criteria in Other Countries 1362
What Level of Treatment Is Necessary? 1365
Risk Assessment 1366
13-3 Introduction to Risk Assessment 1366
Risk Management 1372
Ecological Risk Assessment 1373
Risk Assessment for Water Reuse 1373
Limitations in Risk Assessment for Water Reuse 1374
13-4 Water Reclamation Technologies 1376
Constituent Removal Technologies 1376
Conventional Wastewater Treatment Process Flow Diagrams for Water Reclamation 1377
Advanced Wastewater Treatment Process Flow Diagrams 1379
Performance Expectations for Water Reclamation Processes 1379
Predicting the Performance of Treatment Process Combinations 1387
13-5 Storage of Reclaimed Water 1391
Treatment Process Reliability 1391
Need for Storage 1392
Meeting Water Quality Discharge Requirements 1392
Operation of Storage Reservoirs 1393
Problems Involved with Storage of Reclaimed Water 1397
Management Strategies for Open and Enclosed Reservoirs 1399
13-6 Agricultural and Landscape Irrigation 1401
Evaluation of Irrigation Water Quality 1401
Other Problems 1410
13-7 Industrial Water Reuse 1412
Industrial Water Use 1413
Cooling Tower Makeup Water 1413
Water and Salt Balances in Cooling Tower 1414
Common Water Quality Problems in Cooling Tower Systems 1416
13-8 Groundwater Recharge with Reclaimed Water 1422
Groundwater Recharge Methods 1423
Pretreatment Requirements for Groundwater Recharge 1426
Fate of Contaminants in Groundwater 1427
Groundwater Recharge Guidelines 1429
13-9 Planned Indirect and Direct Potable Water Reuse 1429
Planned Indirect Potable Water Reuse 1431
Planned Direct Potable Water Reuse 1432
Planned Potable Water Reuse Criteria 1432
3-10 Planning for Wastewater Reclamation and Reuse 1433
Planning Basis 1433
What is the Ultimate Water Reuse Goal? 1433
Market Assessment 1434
Monetary Analyses 1435
Other Planning Factors 1436
Planning Report 1437
3-11 Epilogue on Water Reuse Issues 1438
14 Treatment, Reuse,and Disposal of Solids and Biosolids 1447
14-1 Solids Sources, Characteristics,and Quantities 1451
Sources 1451
Characteristics 1451
Quantities 1454
14-2 Regulations for the Reuse and Disposal of Solids in the United States 1460
Pathogen and Vector Attraction Reduction 1461
Land Application 1461
Surface Disposal 1461
Incineration 1464
14-3 Solids Processing Flow Diagrams 1465
14-4 Sludge and Scum Pumping 1465
Pumps 1465
Headloss Determination 1475
Sludge Piping 1481
14-5 Preliminary Operations 1482
Grinding 1482
Screening 1482
Blending 1484
Degritting 1484
Storage 1485
14-6 Thickening 1488
Application 1488
Description and Design of Thickeners 1489
14-7 Introduction to Stabilization 1499
14-8 Alkaline Stabilization 1500
Chemical Reactions in Lime Stabilization 1500
Heat Generation 1502
Application of Alkaline Stabilization Processes 1502
14-9 Anaerobic Digestion 1505
Process Fundamentals 1506
Description of Mesophilic Anaerobic Digestion Processes 1507
Process Design for Mesophilic Anaerobic Digestion 1509
Selection of Tank Design and Mixing System 1516
Methods for Enhancing Solids Loading and Digester Performance 1522
Gas Production, Collection, and Use 1523
Digester Heating 1525
Thermophilic Anaerobic Digestion 1529
Two-Phased Anaerobic Digestion 1531
14-10 Aerobic Digestion 1533
Process Description 1534
Conventional Air Aerobic Digestion 1535
Dual Digestion 1541
Autothermal Thermophilic Aerobic Digestion(ATAD) 1541
High-Purity Oxygen Digestion 1545
14-11 Composting 1546
Process Microbiology 1547
Process Description 1547
Design Considerations 1550
Cocomposting with Municipal Solid Wastes 1551
Public Health and Environmental Issues 1554
14-12 Conditioning 1554
Chemical Conditioning 1555
Other Conditioning Methods 1557
14-13 Dewatering 1558
Centrifugation 1559
Belt-Filter Press 1563
Filter Presses 1565
Sludge Drying Beds 1570
Reed Beds 1578
Lagoons 1578
14-14 Heat Drying 1579
Heat-Transfer Methods 1579
Process Description 1580
Product Characteristics 1584
Product Transport and Storage 1585
Fire and Explosion Hazards 1585
Air Pollution and Odor Control 1585
14-15 Incineration 1586
Fundamental Aspects of Complete Combustion 1587
Multiple-Hearth Incineration 1588
Fluidized-Bed Incineration 1590
Coincineration with Municipal Solid Waste 1592
Air-Pollution Control 1592
14-16 Solids Mass Balances 1592
Preparation of Solids Mass Balances 1593
Performance Data for Solids-Processing Facilities 1593
Impact of Return Flows and Loads 1594
14-17 Application of Biosolids to Land 1608
Site Evaluation and Selection 1609
U.S. EPA Regulations for Beneficial Use and Disposal of Biosolids 1610
Design Loading Rates 1613
Application Methods 1617
Application to Dedicated Lands 1619
Landfilling 1621
14-18 Biosolids Conveyance and Storage 1621
Conveyance Methods 1622
Storage 1622
15 Issues Related to Treatment-Plant Performance 1633
15-1 Need for Upgrading Treatment-Plant Performance 1634
Meeting Current and Future Needs 1634
Meeting More Stringent Discharge Requirements 1635
Discharge Limits for Wastewater Treatment Plants 1635
15-2 Treatment Process Reliability and Selection of Design Values 1636
Variability in Wastewater Treatment 1636
Selection of Process Design Parameters to Meet Discharge Permit Limits 1640
Performance of Combined Processes 1647
Development of Input-Output Data 1649
15-3 Odor Management 1650
Types of Odors 1650
Sources of Odors 1650
Movement of Odors from Wastewater Treatment Facilities 1654
Strategies for Odor Management 1654
Odor-Treatment Methods 1658
Selection and Design of Odor-Control Facilities 1668
Design Considerations for Chemical Scrubbers 1668
Design Considerations for Odor-Control Biofilters 1670
15-4 Introduction to Automatic Process Control 1677
Process Disturbances 1678
Control Systems for Wastewater Treatment Plants 1679
Control Algorithms 1682
Process Control Diagrams 1690
Description of Automatic Control System Elements 1693
15-5 Energy Efficiency in Wastewater Treatment 1703
Overview of the Use of Electricity in Wastewater Treatment 1704
Measures for Improving Energy Efficiency 1705
15-6 Upgrading Wastewater Treatment-Plant Performance 1708
Process Optimization 1708
Upgrading Existing Wastewater Treatment Facilities 1712
Process Design Considerations for Liquid Streams 1721
Process Design Considerations for Solids Processing 1721
15-7 Important Design Considerations for New Wastewater Treatment Plants 1721
Odor Control 1723
Appendixes 1729
A Conversion Factors 1729
B Physical Properties of Selected Gases and the Composition of Air 1737
C Physical Properties of Water 1741
D Solubility of Dissolved Oxygen in Water as a Function of Salinity and Barometric Pressure 1745
E MPN Tables and Their Use 1749
F Carbonate Equilibrium 1753
G Moody Diagrams for the Analysis of Flow in Pipes 1757
Indexes 1759
Name Index 1759
Subject Index 1771