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NITRIFICATION AND ARSENIC REMOVAL IN BIOLOGICALLY ACTIVE FILTERS: A CASE STUDY
Citation:
LYTLE, D. A. NITRIFICATION AND ARSENIC REMOVAL IN BIOLOGICALLY ACTIVE FILTERS: A CASE STUDY. Presented at 2006 ASCE Dayton Section Meeting, Dayton, OH, May 18, 2006.
Impact/Purpose:
To inform the public
Description:
Ammonia in source waters can cause water treatment and distribution system problems, many of which are associated with biological nitrification. Therefore, in some cases, the removal of ammonia from water is desirable. Biological oxidation of ammonia to nitrate and nitrate (nitrification) is well understood and common in wastewater processes. The biological filtration to convert ammonia to nitrate in drinking water applications in full-scale systems is limited in the United States. The purpose of this study was two-fold: (1) to monitor and evaluate nitrification and arsenic removal in a full-scale iron removal filtration plant with biologically active granular media filters located in Ohio, and (2) to determine how to most efficiently regain nitrification and arsenic removal following filter rebedding with new filter media. Results showed that the biologically-active filters consistently oxidized all of the 1.2 mg/L NH3-N to nitrate. Results also suggested that bacteria in the filters were also responsible for oxidation of arsenic. Pilot tests using dual anthracite/sand filters were used to determine the time required to achieve complete nitrification by three different seeding methods of new filters. The results of the pilot tests showed that all three methods took approximately 70 days.