Contents
1. Introduction
1.1Purpose and Scope
1.2Organization
2. Need for and Benefits of Nitrogen and Phosphorus Removal...... 2-1
2.1Introduction...... 2-1
2.2Sources of Nitrogen and Phosphorus in Wastewater...... 2-2
2.2.1Nitrogen...... 2-2
2.2.2Phosphorus...... 2-3
2.3Status of Wastewater Treatment in the U.S...... 2-3
2.4Nutrient Impairment of U.S. Waterways...... 2-5
2.4.1Northern Gulf of Mexico...... 2-6
2.4.2Chesapeake Bay...... 2-6
2.4.3Great Lakes...... 2-6
2.4.4Long Island Sound...... 2-7
2.5Climate Change Impacts...... 2-7
2.6Federal and State Regulations and Initiatives to Reduce Nutrient Pollution....2-8
2.6.1Water Quality Standards...... 2-8
2.6.2Total Maximum Daily Loads (TMDLs)...... 2-10
2.6.3NPDES Permitting...... 2-10
2.6.4Water Quality Trading...... 2-11
2.6.5Technology Evaluation and Guidance...... 2-12
2.7Industry Initiatives – The WERF Nutrient Removal Challenge...... 2-13
2.8Benefits of Nutrient Removal...... 2-14
2.8.1Improved Plant Performance...... 2-14
2.8.2Co-Removal of Emerging Contaminants...... 2-14
2.8.3Nutrient Recovery and Reuse...... 2-15
2.9Challenges of Nutrient Removal...... 2-15
2.9.1Energy Requirements...... 2-15
2.9.2Release of Nitrous Oxide...... 2-17
2.10References...... 2-17
3. Principles of Phosphorus Removal by Chemical Addition...... 3-1
3.1Introduction...... 3-1
3.2Available Forms of Metal Salts and Lime...... 3-1
3.3Equations and Stoichiometry...... 3-2
3.3.1Removable Phosphorus...... 3-2
3.3.2Reactions of Metal Salts and Phosphorus...... 3-2
3.3.3Reactions of Lime with Phosphorus...... 3-4
3.4Points of Application...... 3-5
3.5Solids Separation Processes...... 3-6
3.6Effect on Sludge Production and Handling...... 3-7
3.7Limits of Removal...... 3-8
3.8References...... 3-9
4. Principles of Biological Nitrogen Removal...... 4-1
4.1Introduction...... 4-1
4.2Nitrogen Removal by Biomass Synthesis...... 4-2
4.3Microbiology of Nitrification...... 4-3
4.4Reactions and Stoichiometry of Nitrification...... 4-5
4.5Nitrification Kinetics...... 4-6
4.6 Inhibitory Effects of Environmental Conditions on Nitrification...... 4-16
4.7Denitrification Fundamentals...... 4-19
4.8Microbiology of Denitrification...... 4-19
4.9 Metabolism and Stoichiometry of Heterotrophic Denitrification...... 4-20
4.10Biological Denitrification Kinetics with Influent Wastewater...... 4-21
4.11Denitrification Carbon Sources and Relative Consumption Ratios...... 4-23
4.12Denitrification Kinetics of Exogenous Carbon Sources...... 4-26
4.13Specific Denitrification Rates...... 4-30
4.14Simultaneous Nitrification-Denitrification...... 4-32
4.15Metabolism and Stoichiometry and Kinetics of ANAMMOX®...... 4-33
4.16Impacts on Sludge Production and Handling...... 4-33
4.17References...... 4-34
5. Principles of Biological Phosphorus Removal...... 5-1
5.1Overview of the Biological Phosphorus Removal Process...... 5-1
5.2 Substrate Requirements...... 5-3
5.3Sources of Volatile Fatty Acids...... 5-5
5.3.1Fermentation 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
5.4Environmental Conditions...... 5-9
5.5Kinetics...... 5-12
5.6Important Design and Operational Considerations...... 5-13
5.6.1 Avoiding Secondary Release of Phosphorus...... 5-13
5.6.2 Avoiding Backmixing...... 5-15
5.6.3Flow and Load Balancing...... 5-15
5.7Impacts on Sludge Processing and Handling...... 5-15
5.8References...... 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
6.2.1.1Modified Ludzck Ettinger (MLE) Process...... 6-4
6.2.1.24-Stage Bardenpho...... 6-4
6.2.1.3Sequencing Batch Reactor (SBR)...... 6-5
6.2.1.4Oxidation Ditch with Anoxic Zone...... 6-6
6.2.1.5Step Feed Biological Nitrogen Removal (BNR)...... 6-7
6.2.1.6The Schreiber Process...... 6-8
6.2.1.7Simultaneous Nitrification Denitrification (SNdN)...... 6-8
6.2.1.8Integrated Fixed Film Activated Sludge (IFAS)...... 6-9
6.2.1.9Moving Bed Biofilm Reactor (MBBR)...... 6-10
6.2.1.10Membrane Bioreactor (MBR)...... 6-11
6.2.2Separate Stage Processes - Nitrification...... 6-13
6.2.2.1Suspended Growth Nitrification...... 6-13
6.2.2.2Attached Growth Nitrification...... 6-13
6.2.3Separate Stage Processes - Denitrification...... 6-14
6.2.3.1Denitrification Filters...... 6-14
6.2.3.2Supplemental Carbon...... 6-16
6.2.4Side Stream Treatment Processes...... 6-16
6.3 Phosphorus Removal Technologies...... 6-18
6.3.1 Phosphorus Removal by Chemical Addition...... 6-18
6.3.2 Biological Phosphorus Removal...... 6-21
6.3.2.1Pho-redox (A/O)...... 6-21
6.3.2.2Oxidation Ditch with Anaerobic Zone...... 6-22
6.3.2.3Sludge Fermentation...... 6-23
6.4 Combined Nitrogen and Phosphorus Removal Technologies...... 6-24
6.4.1Biological...... 6-24
6.4.1.13 Stage Pho-redox (A2/0)...... 6-24
6.4.1.25-Stage Bardenpho...... 6-25
6.4.1.3University of Capetown (UCT), Modified UCT, and ...... Virginia Initiative Project (VIP) 6-26
6.4.1.4Westbank...... 6-27
6.4.1.5Oxidation Ditch...... 6-28
6.4.1.6Sequencing Batch Reactor...... 6-29
6.4.1.7Orange Water and Sewer Authority (OWASA)...... 6-29
6.4.2Hybrid Chemical / Biological and Emerging...... 6-30
6.4.2.1Blue Plains Process...... 6-30
6.4.2.2PhoStrip™...... 6-31
6.4.2.3Biological-Chemical Phosphorus and Nitrogen Removal ...... (BCFS) Process 6-31
6.5Effluent Filtration...... 6-32
6.5.1Conventional Down-flow Filters...... 6-33
6.5.2Continuous Backwashing Upflow Sand Filters (Dynasand)...... 6-33
6.5.3Pulsed Bed Filters...... 6-33
6.5.4Traveling-Bridge Filters...... 6-33
6.5.5Fuzzy Filters...... 6-34
6.5.6Discfilters...... 6-34
6.5.7Membranes...... 6-34
6.5.8Blue PROTM Process...... 6-34
6.6 Summary of Attainable Effluent Limits...... 6-35
6.7 Advantages and Disadvantages of Technology Types...... 6-40
6.8 Factors in Simultaneously Achieving Low Nitrogen and Phosphorus ...... Effluent Concentrations 6-44
6.9Summary of Case Studies...... 6-45
6.10 References...... 6-46
7.Establishing Design Objectives...... 7-1
7.1Introduction...... 7-1
7.2 Characterizing Existing Treatment...... 7-2
7.3 Design Flow Rates...... 7-3
7.3.1Characterizing Existing Flow...... 7-3
7.3.2Projecting Future Conditions...... 7-5
7.4 Wastewater characteristics...... 7-6
7.5Target Effluent Concentrations for Total Nitrogen and Total Phosphorus...... 7-7
7.6Goals for Reliability, Sustainability, and Process Flexibility...... 7-11
7.7Sludge Treatment Options...... 7-12
7.8Site Constraints...... 7-12
7.9Selecting an Overall Process Design Factor...... 7-13
7.10Design Examples...... 7-14
7.11References...... 7-14
8. Selecting Candidate Treatment Processes for Plant Upgrades...... 8-1
8.1Introduction...... 8-1
8.2Technology Selection Factors...... 8-1
8.2.1Footprint...... 8-1
8.2.2Hydraulic Considerations...... 8-2
8.2.3Sources of Biodegradable Carbon...... 8-3
8.2.4Chemical needs...... 8-3
8.2.5Available Sludge Treatment and Options...... 8-4
8.2.6Energy Considerations...... 8-4
8.2.7Staffing and Training Requirements...... 8-5
8.3Overview of Recommended Approach...... 8-5
8.4Considerations for Sidestream Treatment...... 8-6
8.5Selecting Alternative Carbon Sources...... 8-8
8.6Selecting Media for Integrated Fixed-Film Activated Sludge (IFAS) Systems.8-9
8.7Recommended Use of Advanced Tools...... 8-10
8.8Patent issues...... 8-11
8.9References...... 8-12
9.Design Approach for Phosphorus Removal by Chemical Addition...... 9-1
9.1Introduction...... 9-1
9.2Selecting a Chemical Precipitant...... 9-1
9.2.1Advantages and Disadvantages of Metal Salts...... 9-1
9.2.2Advantages and Disadvantages of Lime...... 9-3
9.2.3Costs...... 9-3
9.3Selecting Point(s) of Application...... 9-4
9.4Determining the Chemical Dose...... 9-6
9.5 Designing a Chemical Feed System...... 9-9
9.5.1Liquid feed systems...... 9-9
9.5.1.1Storage tanks...... 9-9
9.5.1.2Feed Methods...... 9-9
9.5.2Dry Feed Systems...... 9-12
9.5.2.1Storage...... 9-12
9.5.2.2Feed Methods...... 9-13
9.5.2.3Slaking (lime)...... 9-15
9.6Designing for Rapid Mix and Flocculation...... 9-16
9.6.1Types of Mixers...... 9-16
9.6.2Design Factors...... 9-18
9.6.2.1Velocity Gradient...... 9-18
9.6.2.2Power Requirements...... 9-18
9.6.2.3Hydraulic Retention Time...... 9-20
9.6.2.4Vessel Geometry...... 9-21
9.6.3Summary of Typical Design Parameters...... 9-21
9.7Solids Separation Processes...... 9-22
9.7.1Primary and Secondary Clarification...... 9-23
9.7.2Tertiary Processes...... 9-23
9.8 Operational Factors...... 9-24
9.8.1Dose Control...... 9-24
9.8.2Make-up Water...... 9-24
9.8.3Sludge Production and Handling...... 9-24
9.8.4pH Adjustment...... 9-24
9.8.5Effect on Biosolids Applications...... 9-25
9.9Design Examples...... 9-25
9.10References...... 9-26
10.Design Approach for Biological Nutrient Removal...... 10-1
10.1Introduction...... 10-1
10.2Overview of Recommended Approach...... 10-3
10.3Establishing Modeling Objectives and Requirements...... 10-3
10.3.1Intended Model Use...... 10-5
10.3.2Goals for Model Accuracy...... 10-5
10.3.3Dynamic vs. Steady State Simulation...... 10-5
10.4Selecting a Process Simulation Model...... 10-6
10.5Data Collection...... 10-9
10.5.1Process Configuration...... 10-10
10.5.2Operating Conditions...... 10-13
10.5.3Influent Loading and Wastewater Characteristics...... 10-13
10.5.4Data Verification...... 10-16
10.6Characterization of Organic Material...... 10-21
10.6.1Relationship of Organic Material and Suspended Solids in Wastewater.10-25
10.6.2Methods for Determining COD Fractions...... 10-26
10.6.3Data Checks...... 10-29
10.7 Characterization of Nutrient Fractions...... 10-30
10.7.1Nitrogen...... 10-30
10.7.2Phosphorus...... 10-33
10.8Kinetic and Stoichiometric Parameters...... 10-36
10.9Model Calibration...... 10-37
10.10 Model Validation...... 10-41
10.11Simulation of Design Alternatives for Nutrient Removal...... 10-42
10.12Additional Procedures for Design...... 10-43
10.12.2Denitrification Filters...... 10-44
10.13Design Checks for Biological Nitrogen and Phosphorus Removal...... 10-44
10.14Design Examples...... 10-48
10.15References...... 10-48
11. Design Approach for Effluent Filtration...... 11-1
11.1Introduction...... 11-1
11.2Selection of Filtration Technology...... 11-2
11.3Granular Media Filters...... 11-3
11.3.1Influent Water Quality...... 11-4
11.3.2Media Specifications...... 11-5
11.3.3Filter Loading Rate...... 11-6
11.3.4Filtration Rate...... 11-6
11.3.5Headloss...... 11-6
11.3.6Flow Control...... 11-11
11.4Compressible Media Filters (CMF)...... 11-12
11.5Cloth Media Filters...... 11-13
11.6 Low-Pressure Membranes...... 11-14
11.6.1Membrane Material...... 11-15
11.6.2Membrane Configuration...... 11-15
11.6.3Process Considerations...... 11-16
11.6.4Pressure Drop...... 11-17
11.6.5Flux Determination...... 11-18
11.6.6Performance Data...... 11-19
11.7Emerging Filters for Phosphorus Removal to Low Levels...... 11-19
11.7.1Two-Stage Filtration...... 11-19
11.7.2Iron Oxide Coated Media...... 11-20
11.8Design Examples...... 11-22
11.9 References...... 11-22
12. Operation and Optimization to Enhance Nutrient Removal...... 12-1
12.1Introduction...... 12-1
12.2Analysis of Existing Operations...... 12-1
12.2.1Data Analysis...... 12-2
12.2.2Use of Process Simulation Models...... 12-5
12.3Incorporating SCADA and instrumentation...... 12-6
12.4Common Operational Changes...... 12-6
12.4.1Adjust SRT...... 12-6
12.4.2Adjust Aeration Rates...... 12-7
12.4.3Add Baffles to Create High Food to Microorganism (F/M) Conditions...12-7
12.4.4Change Aeration Settings in Plug Flow Basins...... 12-7
12.4.5Minimize Impact of Recycle Streams...... 12-8
12.4.6Reconfigure Flow through Existing Units...... 12-8
12.4.7Increase VFA for Biological Phosphorus Removal...... 12-9
12.5References...... 12-9
13.Instrumentation and Controls
13.1Introduction...... 13-1
13.2Factors in Selecting Instrumentation...... 13-1
13.3 Basic Online Instrumentation...... 13-2
13.3.1Flow...... 13-3
13.3.2TSS...... 13-4
13.3.3Sludge Blanket Depth...... 13-5
13.3.4Dissolved Oxygen...... 13-5
13.3.5pH...... 13-5
13.3.6ORP...... 13-6
13.4Instrumentation for Nutrient Control...... 13-6
13.4.1Ammonia...... 13-7
13.4.2Nitrate and Nitrite...... 13-7
13.4.3Phosphate and Total Phosphorus...... 13-8
13.4.5Turbidity...... 13-8
13.4.6Total Organic Carbon...... 13-8
13.4.7NADH (active biomass)...... 13-9
13.5Types of Control...... 13-9
13.5.1Feed-forward...... 13-9
13.5.2Feedback...... 13-10
13.5.3Feed-forward and feedback...... 13-10
13.5.4Cascade...... 13-10
13.6Automated Control and Optimization for Basic Parameters...... 13-11
13.6.1Dissolved Oxygen...... 13-11
13.6.2Solids Retention Time...... 13-11
13.6.3ORP...... 13-12
13.7Advanced Automated Control for Nutrient Removal...... 13-12
13.7.1Nitrogen (various forms)...... 13-12
13.7.2Orthophosphate...... 13-13
13.7.3Respirometry...... 13-13
13.8Control Equipment – SCADA...... 13-13
13.9References...... 13-14
14.Sustainable Nutrient Recovery and Reuse...... 14-1
14.1Introduction...... 14-1
14.2Separating and Treating Waste On-Site...... 14-1
14.3Using Wastewater Treatment By-Products...... 14-2
14.3.1Durham (OR) Advanced Wastewater Treatment Facility...... 14-3
14.3.2East Bay Municipal Utility District (CA)...... 14-3
14.3.3Stamford (CT) Water Pollution Control Agency...... 14-4
14.4References...... 14-4
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
DRAFT Nutrient Control Design Manual 1March 2009
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