1 Antimicrobial-Coated Granular Filter Media for Drinking Water Treatment

ability of quaternary ammonia compound (QAC) coated granular media to sustain antimicrobial activity at a drinking water treatment plant. Previous bench-scale testing had demonstrated that QAC coated media was capable of inactivating 1 to 2 logs of bacteria while negligible removal was observed with non-coated media. The research project was accomplished by operating four different 2.5 inch diameter filters each containing two feet of a different media. Sand and quaternary ammonium coated (QAC) sand with an effective size range of 0.45-.55 mm were in two filters. Zeolite and quaternary ammonium coated zeolite with an effective size range of 0.45-0.55 mm were in the other two filters. By operating both coated and uncoated media filters identically, the antimicrobial efficacy of the coated media was evaluated. The filters were operated at a typical hydraulic loading rate (2 gpm/ft2) for a single media filter used at a surface water treatment plant. Backwashing was done by expanding the beds 25 % when the head loss on the filters became greater than 3 feet. The filters were monitored daily for flowrate, pH, turbidity and head loss. Challenge testing was done weekly by spiking the influent with the indicator bacteria Escherichia coli and/or the bacteriophage PRD-1. Th