Contents
1.
Introduction
1.1
Purpose and Scope
1.2
Organization
2.
Need for and Benefits of Nitrogen and Phosphorus Removal.............................................. 2-1
2.1
Introduction
....................................................................................................... 2-1
2.2
Sources of Nitrogen and Phosphorus in Wastewater .............................................. 2-2
2.2.1 Nitrogen ...................................................................................................... 2-2
2.2.2 Phosphorus ................................................................................................. 2-3
2.3
Status of Wastewater Treatment in the U.S. ........................................................... 2-3
2.4
Nutrient Impairment of U.S. Waterways ................................................................. 2-5
2.4.1 Northern Gulf of Mexico ............................................................................. 2-6
2.4.2 Chesapeake Bay ......................................................................................... 2-6
2.4.3 Great Lakes ................................................................................................. 2-6
2.4.4 Long Island Sound ....................................................................................... 2-7
2.5
Climate Change Impacts .......................................................................................... 2-7
2.6
Federal and State Regulations and Initiatives to Reduce Nutrient Pollution .......... 2-8
2.6.1 Water Quality Standards ............................................................................ 2-8
2.6.2 Total Maximum Daily Loads (TMDLs) ......................................................... 2-10
2.6.3 NPDES Permitting ....................................................................................... 2-10
2.6.4 Water Quality Trading ................................................................................ 2-11
2.6.5 Technology Evaluation and Guidance......................................................... 2-12
2.7
Industry Initiatives – The WERF Nutrient Removal Challenge ................................. 2-13
2.8
Benefits of Nutrient Removal .................................................................................. 2-14
2.8.1 Improved Plant Performance...................................................................... 2-14
2.8.2 Co-Removal of Emerging Contaminants ..................................................... 2-14
2.8.3 Nutrient Recovery and Reuse ..................................................................... 2-15
2.9
Challenges of Nutrient Removal .............................................................................. 2-15
2.9.1 Energy Requirements.................................................................................. 2-15
2.9.2 Release of Nitrous Oxide ............................................................................ 2-17
2.10 References
....................................................................................................... 2-17
3.
Principles of Phosphorus Removal by Chemical Addition .................................................... 3-1
3.1
Introduction
....................................................................................................... 3-1
3.2
Available Forms of Metal Salts and Lime ................................................................. 3-1
3.3
Equations and Stoichiometry ................................................................................... 3-2
3.3.1 Removable Phosphorus .............................................................................. 3-2
3.3.2 Reactions of Metal Salts and Phosphorus .................................................. 3-2
3.3.3 Reactions of Lime with Phosphorus............................................................ 3-4
3.4
Points of Application ................................................................................................ 3-5
3.5
Solids Separation Processes ..................................................................................... 3-6
3.6
Effect on Sludge Production and Handling .............................................................. 3-7
3.7
Limits of Removal..................................................................................................... 3-8
3.8
References
....................................................................................................... 3-9
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4.
Principles of Biological Nitrogen Removal ............................................................................ 4-1
4.1
Introduction
....................................................................................................... 4-1
4.2
Nitrogen Removal by Biomass Synthesis ................................................................. 4-2
4.3
Microbiology of Nitrification.................................................................................... 4-3
4.4
Reactions and Stoichiometry of Nitrification........................................................... 4-5
4.5
Nitrification Kinetics................................................................................................. 4-6
4.6
Inhibitory Effects of Environmental Conditions on Nitrification ............................. 4-16
4.7
Denitrification Fundamentals .................................................................................. 4-19
4.8
Microbiology of Denitrification ................................................................................ 4-19
4.9
Metabolism and Stoichiometry of Heterotrophic Denitrification ........................... 4-20
4.10 Biological Denitrification Kinetics with Influent Wastewater .................................. 4-21
4.11 Denitrification Carbon Sources and Relative Consumption Ratios.......................... 4-23
4.12 Denitrification Kinetics of Exogenous Carbon Sources ............................................ 4-26
4.13 Specific Denitrification Rates ................................................................................... 4-30
4.14 Simultaneous Nitrification-Denitrification............................................................... 4-32
4.15 Metabolism and Stoichiometry and Kinetics of ANAMMOX® ................................. 4-33
4.16 Impacts on Sludge Production and Handling ........................................................... 4-33
4.17 References
....................................................................................................... 4-34
5.
Principles of Biological Phosphorus Removal ....................................................................... 5-1
5.1
Overview of the Biological Phosphorus Removal Process ....................................... 5-1
5.2
Substrate Requirements .......................................................................................... 5-3
5.3
Sources of Volatile Fatty Acids ................................................................................. 5-5
5.3.1 Fermentation in the Collection System ...................................................... 5-6
5.3.2 Anaerobic Fermentation of Primary or Return Activated Sludge ............... 5-7
5.3.3 Commercial Sources ................................................................................... 5-9
5.4
Environmental Conditions ....................................................................................... 5-9
5.5
Kinetics
....................................................................................................... 5-12
5.6
Important Design and Operational Considerations ................................................. 5-13
5.6.1 Avoiding Secondary Release of Phosphorus ............................................... 5-13
5.6.2 Avoiding Backmixing ................................................................................... 5-15
5.6.3 Flow and Load Balancing ............................................................................ 5-15
5.7
Impacts on Sludge Processing and Handling ........................................................... 5-15
5.8
References
....................................................................................................... 5-16
6.
Overview of Nitrogen and Phosphorus Removal Technologies ........................................... 6-1
6. 1
Introduction
....................................................................................................... 6-1
6.2
Nitrogen Removal Technologies .............................................................................. 6-2
6.2.1 Nitrogen Removal in Single Process Unit.................................................... 6-4
6.2.1.1 Modified Ludzck Ettinger (MLE) Process ....................................... 6-4
6.2.1.2 4-Stage Bardenpho ........................................................................ 6-4
6.2.1.3 Sequencing Batch Reactor (SBR).................................................... 6-5
6.2.1.4 Oxidation Ditch with Anoxic Zone ................................................. 6-6
6.2.1.5 Step Feed Biological Nitrogen Removal (BNR) .............................. 6-7
6.2.1.6 The Schreiber Process .................................................................... 6-8
6.2.1.7 Simultaneous Nitrification Denitrification (SNdN) ........................ 6-8
6.2.1.8 Integrated Fixed Film Activated Sludge (IFAS) ............................... 6-9
6.2.1.9 Moving Bed Biofilm Reactor (MBBR) ............................................. 6-10
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6.2.1.10 Membrane Bioreactor (MBR) ..................................................... 6-11
Separate Stage Processes - Nitrification ..................................................... 6-13
6.2.2.1 Suspended Growth Nitrification .................................................... 6-13
6.2.2.2 Attached Growth Nitrification ....................................................... 6-13
6.2.3 Separate Stage Processes - Denitrification ................................................. 6-14
6.2.3.1 Denitrification Filters ..................................................................... 6-14
6.2.3.2 Supplemental Carbon .................................................................... 6-16
6.2.4 Side Stream Treatment Processes .............................................................. 6-16
Phosphorus Removal Technologies ......................................................................... 6-18
6.3.1 Phosphorus Removal by Chemical Addition ............................................... 6-18
6.3.2 Biological Phosphorus Removal .................................................................. 6-21
6.3.2.1 Pho-redox (A/O) ............................................................................. 6-21
6.3.2.2 Oxidation Ditch with Anaerobic Zone ............................................ 6-22
6.3.2.3 Sludge Fermentation ..................................................................... 6-23
Combined Nitrogen and Phosphorus Removal Technologies ................................. 6-24
6.4.1 Biological ..................................................................................................... 6-24
6.4.1.1 3 Stage Pho-redox (A2/0)............................................................... 6-24
6.4.1.2 5-Stage Bardenpho ........................................................................ 6-25
6.4.1.3 University of Capetown (UCT), Modified UCT, and ......................
Virginia Initiative Project (VIP) ....................................................... 6-26
6.4.1.4 Westbank ....................................................................................... 6-27
6.4.1.5 Oxidation Ditch .............................................................................. 6-28
6.4.1.6 Sequencing Batch Reactor ............................................................. 6-29
6.4.1.7 Orange Water and Sewer Authority (OWASA) .............................. 6-29
6.4.2 Hybrid Chemical / Biological and Emerging ................................................ 6-30
6.4.2.1 Blue Plains Process......................................................................... 6-30
6.4.2.2 PhoStrip™....................................................................................... 6-31
6.4.2.3 Biological-Chemical Phosphorus and Nitrogen Removal ..............
(BCFS) Process................................................................................ 6-31
Effluent Filtration ..................................................................................................... 6-32
6.5.1 Conventional Down-flow Filters ................................................................. 6-33
6.5.2 Continuous Backwashing Upflow Sand Filters (Dynasand)......................... 6-33
6.5.3 Pulsed Bed Filters........................................................................................ 6-33
6.5.4 Traveling-Bridge Filters ............................................................................... 6-33
6.5.5 Fuzzy Filters................................................................................................. 6-34
6.5.6 Discfilters .................................................................................................... 6-34
6.5.7 Membranes ................................................................................................. 6-34
6.5.8 Blue PROTM Process ................................................................................... 6-34
Summary of Attainable Effluent Limits .................................................................... 6-35
Advantages and Disadvantages of Technology Types ............................................. 6-40
Factors in Simultaneously Achieving Low Nitrogen and Phosphorus .....................
Effluent Concentrations ........................................................................................... 6-44
Summary of Case Studies......................................................................................... 6-45
References
....................................................................................................... 6-46
6.2.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
6.10
7.
Establishing Design Objectives.............................................................................................. 7-1
7.1
Introduction
....................................................................................................... 7-1
7.2
Characterizing Existing Treatment ........................................................................... 7-2
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7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
Design Flow Rates .................................................................................................... 7-3
7.3.1 Characterizing Existing Flow ....................................................................... 7-3
7.3.2 Projecting Future Conditions ...................................................................... 7-5
Wastewater characteristics ..................................................................................... 7-6
Target Effluent Concentrations for Total Nitrogen and Total Phosphorus.............. 7-7
Goals for Reliability, Sustainability, and Process Flexibility ..................................... 7-11
Sludge Treatment Options ....................................................................................... 7-12
Site Constraints ....................................................................................................... 7-12
Selecting an Overall Process Design Factor ............................................................. 7-13
Design Examples ...................................................................................................... 7-14
References
....................................................................................................... 7-14
8. Selecting Candidate Treatment Processes for Plant Upgrades..................................................... 8-1
8.1
Introduction....................................................................................................... 8-1
8.2
Technology Selection Factors ............................................................................ 8-1
8.2.1
Footprint ........................................................................................ 8-1
8.2.2
Hydraulic Considerations ............................................................... 8-2
8.2.3
Sources of Biodegradable Carbon ................................................. 8-3
8.2.4
Chemical needs .............................................................................. 8-3
8.2.5
Available Sludge Treatment and Options ...................................... 8-4
8.2.6
Energy Considerations ................................................................... 8-4
8.2.7
Staffing and Training Requirements .............................................. 8-5
8.3
Overview of Recommended Approach ............................................................. 8-5
8.4
Considerations for Sidestream Treatment ........................................................ 8-6
8.5
Selecting Alternative Carbon Sources ............................................................... 8-8
8.6
Selecting Media for Integrated Fixed-Film Activated Sludge (IFAS) Systems.... 8-9
8.7
Recommended Use of Advanced Tools............................................................. 8-10
8.8
Patent issues...................................................................................................... 8-11
8.9
References ....................................................................................................... 8-12
9.
Design Approach for Phosphorus Removal by Chemical Addition ....................................... 9-1
9.1
Introduction
....................................................................................................... 9-1
9.2
Selecting a Chemical Precipitant.............................................................................. 9-1
9.2.1 Advantages and Disadvantages of Metal Salts ........................................... 9-1
9.2.2 Advantages and Disadvantages of Lime ..................................................... 9-3
9.2.3 Costs ....................................................................................................... 9-3
9.3
Selecting Point(s) of Application .............................................................................. 9-4
9.4
Determining the Chemical Dose .............................................................................. 9-6
9.5
Designing a Chemical Feed System ......................................................................... 9-9
9.5.1 Liquid feed systems .................................................................................... 9-9
9.5.1.1 Storage tanks ................................................................................. 9-9
9.5.1.2 Feed Methods ................................................................................ 9-9
9.5.2 Dry Feed Systems ........................................................................................ 9-12
9.5.2.1 Storage ........................................................................................... 9-12
9.5.2.2 Feed Methods ................................................................................ 9-13
9.5.2.3 Slaking (lime).................................................................................. 9-15
9.6
Designing for Rapid Mix and Flocculation ............................................................... 9-16
9.6.1 Types of Mixers ........................................................................................... 9-16
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9.6.2
9.7
9.8
9.9
9.10
10.
Design Factors ............................................................................................. 9-18
9.6.2.1 Velocity Gradient ........................................................................... 9-18
9.6.2.2 Power Requirements ..................................................................... 9-18
9.6.2.3 Hydraulic Retention Time .............................................................. 9-20
9.6.2.4 Vessel Geometry ............................................................................ 9-21
9.6.3 Summary of Typical Design Parameters ..................................................... 9-21
Solids Separation Processes ..................................................................................... 9-22
9.7.1 Primary and Secondary Clarification........................................................... 9-23
9.7.2 Tertiary Processes ....................................................................................... 9-23
Operational Factors ................................................................................................ 9-24
9.8.1 Dose Control ............................................................................................... 9-24
9.8.2 Make-up Water ........................................................................................... 9-24
9.8.3 Sludge Production and Handling ................................................................ 9-24
9.8.4 pH Adjustment ............................................................................................ 9-24
9.8.5 Effect on Biosolids Applications .................................................................. 9-25
Design Examples ...................................................................................................... 9-25
References
....................................................................................................... 9-26
Design Approach for Biological Nutrient Removal ............................................................... 10-1
10.1 Introduction
....................................................................................................... 10-1
10.2 Overview of Recommended Approach .................................................................... 10-3
10.3 Establishing Modeling Objectives and Requirements ............................................. 10-3
10.3.1 Intended Model Use ................................................................................... 10-5
10.3.2 Goals for Model Accuracy ........................................................................... 10-5
10.3.3 Dynamic vs. Steady State Simulation.......................................................... 10-5
10.4 Selecting a Process Simulation Model ..................................................................... 10-6
10.5 Data Collection ....................................................................................................... 10-9
10.5.1 Process Configuration ................................................................................. 10-10
10.5.2 Operating Conditions .................................................................................. 10-13
10.5.3 Influent Loading and Wastewater Characteristics...................................... 10-13
10.5.4 Data Verification ......................................................................................... 10-16
10.6 Characterization of Organic Material ...................................................................... 10-21
10.6.1 Relationship of Organic Material and Suspended Solids in Wastewater ... 10-25
10.6.2 Methods for Determining COD Fractions ................................................... 10-26
10.6.3 Data Checks................................................................................................. 10-29
10.7 Characterization of Nutrient Fractions .................................................................... 10-30
10.7.1 Nitrogen ...................................................................................................... 10-30
10.7.2 Phosphorus ................................................................................................. 10-33
10.8 Kinetic and Stoichiometric Parameters ................................................................... 10-36
10.9 Model Calibration .................................................................................................... 10-37
10.10 Model Validation ..................................................................................................... 10-41
10.11 Simulation of Design Alternatives for Nutrient Removal ........................................ 10-42
10.12 Additional Procedures for Design ............................................................................ 10-43
10.12.2 Denitrification Filters .................................................................................. 10-44
10.13 Design Checks for Biological Nitrogen and Phosphorus Removal ........................... 10-44
10.14 Design Examples ...................................................................................................... 10-48
10.15 References
....................................................................................................... 10-48
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11. Design Approach for Effluent Filtration ....................................................................................... 11-1
11.1 Introduction
....................................................................................................... 11-1
11.2 Selection of Filtration Technology ........................................................................... 11-2
11.3 Granular Media Filters ............................................................................................. 11-3
11.3.1 Influent Water Quality ................................................................................ 11-4
11.3.2 Media Specifications ................................................................................... 11-5
11.3.3 Filter Loading Rate ...................................................................................... 11-6
11.3.4 Filtration Rate ............................................................................................. 11-6
11.3.5 Headloss ...................................................................................................... 11-6
11.3.6 Flow Control................................................................................................ 11-11
11.4 Compressible Media Filters (CMF) ........................................................................... 11-12
11.5 Cloth Media Filters ................................................................................................... 11-13
11.6 Low-Pressure Membranes ....................................................................................... 11-14
11.6.1 Membrane Material.................................................................................... 11-15
11.6.2 Membrane Configuration ........................................................................... 11-15
11.6.3 Process Considerations ............................................................................... 11-16
11.6.4 Pressure Drop ............................................................................................. 11-17
11.6.5 Flux Determination ..................................................................................... 11-18
11.6.6 Performance Data ....................................................................................... 11-19
11.7 Emerging Filters for Phosphorus Removal to Low Levels ........................................ 11-19
11.7.1 Two-Stage Filtration.................................................................................... 11-19
11.7.2 Iron Oxide Coated Media ............................................................................ 11-20
11.8 Design Examples ...................................................................................................... 11-22
11.9 References
....................................................................................................... 11-22
12. Operation and Optimization to Enhance Nutrient Removal........................................................ 12-1
12.1 Introduction
....................................................................................................... 12-1
12.2 Analysis of Existing Operations ................................................................................ 12-1
12.2.1 Data Analysis ............................................................................................... 12-2
12.2.2 Use of Process Simulation Models.............................................................. 12-5
12.3 Incorporating SCADA and instrumentation ............................................................. 12-6
12.4 Common Operational Changes ................................................................................ 12-6
12.4.1 Adjust SRT ................................................................................................... 12-6
12.4.2 Adjust Aeration Rates ................................................................................. 12-7
12.4.3 Add Baffles to Create High Food to Microorganism (F/M) Conditions....... 12-7
12.4.4 Change Aeration Settings in Plug Flow Basins ............................................ 12-7
12.4.5 Minimize Impact of Recycle Streams .......................................................... 12-8
12.4.6 Reconfigure Flow through Existing Units .................................................... 12-8
12.4.7 Increase VFA for Biological Phosphorus Removal ...................................... 12-9
12.5 References
....................................................................................................... 12-9
13.
Instrumentation and Controls
13.1 Introduction
....................................................................................................... 13-1
13.2 Factors in Selecting Instrumentation ....................................................................... 13-1
13.3 Basic Online Instrumentation .................................................................................. 13-2
13.3.1 Flow
....................................................................................................... 13-3
13.3.2 TSS
....................................................................................................... 13-4
13.3.3 Sludge Blanket Depth.................................................................................. 13-5
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13.4
13.5
13.6
13.7
13.8
13.9
14.
13.3.4 Dissolved Oxygen ........................................................................................ 13-5
13.3.5 pH
....................................................................................................... 13-5
13.3.6 ORP
....................................................................................................... 13-6
Instrumentation for Nutrient Control ...................................................................... 13-6
13.4.1 Ammonia..................................................................................................... 13-7
13.4.2 Nitrate and Nitrite....................................................................................... 13-7
13.4.3 Phosphate and Total Phosphorus ............................................................... 13-8
13.4.5 Turbidity ...................................................................................................... 13-8
13.4.6 Total Organic Carbon .................................................................................. 13-8
13.4.7 NADH (active biomass) ............................................................................... 13-9
Types of Control ....................................................................................................... 13-9
13.5.1 Feed-forward .............................................................................................. 13-9
13.5.2 Feedback ..................................................................................................... 13-10
13.5.3 Feed-forward and feedback........................................................................ 13-10
13.5.4 Cascade ....................................................................................................... 13-10
Automated Control and Optimization for Basic Parameters ................................... 13-11
13.6.1 Dissolved Oxygen ........................................................................................ 13-11
13.6.2 Solids Retention Time ................................................................................. 13-11
13.6.3 ORP
....................................................................................................... 13-12
Advanced Automated Control for Nutrient Removal .............................................. 13-12
13.7.1 Nitrogen (various forms)............................................................................. 13-12
13.7.2 Orthophosphate ......................................................................................... 13-13
13.7.3 Respirometry .............................................................................................. 13-13
Control Equipment – SCADA .................................................................................... 13-13
References
....................................................................................................... 13-14
Sustainable Nutrient Recovery and Reuse............................................................................ 14-1
14.1 Introduction
....................................................................................................... 14-1
14.2 Separating and Treating Waste On-Site................................................................... 14-1
14.3 Using Wastewater Treatment By-Products ............................................................. 14-2
14.3.1 Durham (OR) Advanced Wastewater Treatment Facility ........................... 14-3
14.3.2 East Bay Municipal Utility District (CA) ....................................................... 14-3
14.3.3 Stamford (CT) Water Pollution Control Agency .......................................... 14-4
14.4 References
....................................................................................................... 14-4
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Appendices
Appendix M.
Recommendations for Methanol Safety
Appendix N.
Organic Compounds and Inhibitory Concentrations to Nitrification
Appendix Y.
Mathematical Models for Wastewater Treatment
Appendix Z.
Case Studies
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