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effects such as odor complaints and sulfide-induced corrosion. Chemical addition and physical modifications to the collection system can be implemented to reduce sulfide production, although such changes also reduce fermentation to make rbCOD. Odor and sulfide-corrosion control methods include addition of oxidants (e.g., chlorine, hydrogen peroxide) to destroy hydrogen sulfide or injection of oxygen or addition of nitrate to modify the sewer environment from anaerobic to anoxic or oxic and stop formation of hydrogen sulfide (Kobylinski, et al. 2008). Such chemical additions are intended to stop fermentation and reduce sulfide concentration in the sewer, but they also result in the loss of rbCOD, thereby hurting EBPR performance. The only proven sulfide control approach that will not significantly impact EBPR performance is the addition of iron. Iron specifically reacts with hydrogen sulfide but does not impact rbCOD concentrations and has no impact on microbial activity to produce VFA. Where To Start If you're now wondering whether you have to choose between fermentation in the collection system (risking infrastructure damage and odor complaints) or chemical addition to remove phosphorus, it's time to step back. Utilities that are considering implementation of EBPR to meet new or lower phosphorus limits should begin with a comprehensive/coordinated plan for the collection system and WWTP improvements. Comprehensive influent wastewater characterization can help you determine the quantity and reliability/ consistency of the influent carbon source (rbCOD) to support EBPR. Knowing the incoming wastewater quality will help determine if the level of hydrogen sulfide control needed to protect a collection system from excessive corrosion will interfere with or stop collection system fermentation, making it necessary to add a fermentation process for reliable EBPR at the WWTP site. To make sure utility investments culminate in facilities that meet future capacity needs and comply with anticipated permit requirements, WWTP designers tend to make relatively conservative assumptions. Such assumptions help address unknowns such as how much VFA or rbCOD is available in the influent throughout seasonal fluctuations but tend to increase project costs. Availability of historical data reduces the need for assumptions, which in turn reduces capital costs. Additionally, arbitrarily reducing VFA in collection systems to control odors may be counterproductive. The best approach in planning is to understand the balance between odor generation in the collection system and the cost of VFA production at the WWTP. Ultimately, sampling today to generate a good historical database of these different influent wastewater characteristics will reduce the need for assumptions and allow better definition of the facilities necessary for plant upgrades to meet new phosphorus effluent limits. Good influent characterization builds confidence that the new facilities will achieve permit compliance. It also allows for optimized design and operations to reduce capital investment. Good sampling data provides a reasonable basis to defend the plant upgrade design to regulatory review, especially when phosphorus removal is new to a state. We all know the value of starting with the end in mind. If phosphorus removal is your goal, enhanced biological phosphorus removal may be your best direction. Careful consideration of process needs and related side effects, combined with maximum knowledge about your influent characteristics and system needs, can smooth potential bumps on the road to compliance. Planning and influent sampling today can save you money in the future. Reference Kobylinski, E., Van Durme, G., Barnard, J., Massart, N., Koh, SH; "How to overcome hydrogen sulfide problems while preserving biological phosphorus removal," WE&T; Operations Forum, October 2008. Ed Kobylinski is a senior treatment process engineer and Mark Steichen is director of wastewater process in the Kansas City, MO, office of Black & Veatch. Dave Koch leads Black & Veatch's Chicago office. Dave Bunch has been an engineer/project manager for numerous EBPR projects in the Midwest, and Tom Ratzki is the Midwest client relations director in the St. Louis, MO, office of Black & Veatch. All have considerable experience with nutrient management. wateronline.com ■ Water Online The Magazine MLSS fermentation was included in a nutrient management project at a wastewater treatment plant in the Midwestern U.S. to help improve EBPR performance. (Credit: Black & Veatch) Kobylinski Steichen Koch Bunch Ratzki BNR 101: Tutorial 16