MOP 109 & WEF MOP 30 describes the theory, equipment, and practical techniques needed to optimize BNR in varied environments.

Increasing energy costs and climate change necessitate an optimization of energy use at wastewater treatment plants for a sustainable future. Aeration within the biological nutrient removal (BNR) process accounts for a large portion of energy consumption at a wastewater treatment plant. As such, reducing the aeration input is considered a primary solution to reducing the energy required for wastewater treatment. While successful BNR at lower than conventional dissolved oxygen (DO) concentrations has been demonstrated, challenges remain before reduced aeration can be implemented at full-scale. In Chapter 1, we first compared two automated aeration control strategies under low-DO conditions in two pilot-scale treatment systems. We showed that effective, year-round BNR can be achieved with both strategies by increasing the solids retention time. However, both pilot-scale processes experienced poor solids settleability during the winter. While settleability was recovered during warmer temperatures, improving settling quality under low-DO remains a challenged to be resolved. In Chapter 2, we investigated the short- and long-term effect of DO reductions on the production and emission of nitrous oxide, a potent greenhouse gas. We found that while increases in nitrous oxide production and emission immediately followed DO reductions, long-term emissions decreased after prolonged operation under low-DO conditions. Process nuisances and performance deviations (e.g. nitrite accumulation) also corresponded with increased emissions. Finally, in Chapter 3, we used genome-resolved metagenomics and metatranscriptomics to explore the diversity and dynamics of the Candidatus Accumlibacter lineage, key organisms contributing to phosphorus removal from wastewater. We found that Accumulibacter community was highly diverse across time in multiple pilot-scale low-DO systems, supporting evidence that most members of this lineage have a high affinity for oxygen. The information gained in these studies expands on the feasibility and implications of low-DO wastewater treatment at full-scale and adds to our understanding of the microbial community carrying out BNR under these conditions.

Contents - List of Tables - List of Figures - PART ONE: NITRIFICATION - Chapter 1 Introduction - Chapter 2 Nitrogenous and Phosphorous Compounds - Chapter 3 Nitrification: The Basics - Chapter 4 Nitrifying Bacteria - Chapter 5 Nitrification and Limiting Factors - Chapter 6 Promoting Nitrification - PART TWO: DENITRIFICATION - Chapter 7 Denitrification: The Basics - Chapter 8 Denitrifying Bacteria - Chapter 9 Denitrification and Limiting Factors - PART THREE: BIOLOGICAL PHOSPHORUS REMOVAL - Chapter 10 Biological Phosphorus Removal: The Basics - Chapter 11 EBPR: Process Control - Abbreviations and Acronyms - Glossary - Bibliography - Biological nutrient removal (BNR), the removal of nitrogen and phosphorus from wastewater, is a complex process. Although the activated sludge process is an efficient technology for the removal of biochemical oxygen demand (BOD) and total suspended solids (TSS), it provides less-than-optimal conditions for the removal of nitrogen and phosphorus, and presents numerous challenges to the operator trying to satisfy the many requirements for several different groups of bacteria. In addition to satisfying the requirements there are numerous, highly variable operational conditions that impact BNR. These conditions include: changes in strength and composition of the wastewater, alkalinity and pH, temperature, and presence of inhibitory and toxic wastes. Even fluctuations in flows, especially from inflow and infiltration, can adversely impact the aerobic, anoxic, and anaerobic conditions needed for successful BNR. Of the three treatment processes, nitrification, denitrification, and enhanced biological removal, nitrification is often the most difficult to achieve. Therefore, a large portion of this book reviews nitrification. Operators of the activated sludge process need to understand the basic biological, chemical, and physical requirements for BNR in order to improve the performance of these treatment processes. An Operator's Guide to Biological Nutrient Removal (BNR) in the Activated Sludge Process is intended to help operators in the monitoring, troubleshooting, and process control of BNR. Numerous tables and figures are included in the book to help the operator understand the biological and chemical reactions that are involved in BNR processes and how the reactions can be monitored for process control. Design of BNR processes is not addressed in this book. Design is addressed in numerous engineering publications. The book serves to help operators achieve permit compliance for nitrogen and phosphorus discharge limits and obtain cost-effective operation. -

BNR is a fast-growing method of removing biological pollutants (bacteria, etc.) from wastewater. Experts from both the Water Environment Federation and the American Society of Civil Engineers have collaborated on this definitive work which is intended to be a practical manual for plant managers and operators who needed current information on BNR.

This book presents information that can be used for the design and operation of wastewater treatment plants that utilize biological nutrient removal processes, i.e., processes that utilize biological mechanisms instead of chemical mechanisms, to remove phosphorus and nitrogen from wastewaters. The book provides: basic fundamentals, concepts, and theories; design of prefermentation units, various types of BNR systems, and secondary clarifiers; retrofitting conventional activated sludge plants; modeling considerations; and special considerations for BNR systems. It includes full-scale and pilot plant case histories, design examples, and retrofit of existing plants.

Annotation This manual is ideal for plant managers, operators, design engineers, and regulators looking to gain a better understanding of fundamental biological and chemical processes that are in use at nutrient removal facilities and the ways that operators may use, monitor, and control these processes to meet their facility's treatment goal. Table of contents Chapter 1: Introduction Chapter 2: Wastewater Constituents that Affect Nutrient Removal Chapter 3: Nitrification Chapter 4: Nitrification in Biofilm Reactors Chapter 5: Denitrification Chapter 6: Combined Nitrifying and Denitrifying Systems Chapter 7: Enhanced Biological Phosphorus Removal Chapter 8: Chemical Precipitation of Phosphorus Chapter 9: Enhanced Biological Phosphorus Removal Systems Chapter 10: Combined Nitrogen and Phosphorus Removal Processes Chapter 11: Optimization of Nutrient Removal Systems Chapter 12: Recycle Streams Management Chapter 13: Process Control Using Oxidation-Reduction Potential and Dissolved Oxygen Chapter 14: Process Control, Instrumentation, and Automation Chapter 15: Laboratory Analyses Chapter 16: Case Studies-Nitrification and Denitrification Chapter 17: Case Studies-Enhanced Biological Phosphorus Removal Appendix A Optimization and Troubleshooting Guides This book was prepared by the Operation of Nutrient Removal Facilities Task Force of the Water Environment Federation.