Struvite accumulation is a costly problem in many water resource recovery facilities (WRRFs) that use anaerobic digestion, causing significant labor and equipment costs and potentially impacting facility performance and permit compliance. A comprehensive study was undertaken to evaluate possible solutions to struvite control at two similar Miami-Dade County, Florida, WRRFs. Alternatives analyzed included periodic cleaning and repair of damaged piping and equipment; optimum ferric salt dosing, use of in situ scaling coupons; and engineered struvite precipitation. The effectiveness and cost of each alternative was evaluated using a newly constructed dynamic process model and a net present worth analysis. Results indicate that nutrient recovery was a potential benefit at both facilities. This study establishes a comprehensive process and specific testing protocols for evaluating struvite control alternatives.

2015 NTRY1R12aii The Water Environment Research Foundation, a not-for-profit organization, funds and manages water quality research for its subscribers through a diverse public-private partnership between municipal utilities, corporations, academia, industry, and the federal government. WERF subscribers include municipal and regional water and water resource recovery facilities, industrial corporations, environmental engineering firms, and others that share a commitment to cost-effective water quality solutions. WERF is dedicated to advancing science and technology addressing water quality issues as they impact water resources, the atmosphere, the lands, and quality of life.For more information, contact: Water Environment Research Foundation

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The objective of this paper is to identify the importance of kinetic parameters relating to the utilization of nitrite when nitrification and denitrification are modeled as two-step processes. This is an important issue relating to modeling for design and in operation of plants achieving low effluent TN concentrations. A case study using a calibrated model of a full scale plant achieving low effluent TN is used to demonstrate the impacts of key modeling parameters on effluent predictions. The results also demonstrate the importance of full scale plant calibration based on historical data and detailed plant sampling and profiling.