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Arsenic exists in two oxidation states in water,arsenite [As(III)] and arsenate [As(V)]. As(III) is relativelymobile in water and difficult to remove byarsenic-removal treatment processes. Source watersthat contain As(III) must add a strong oxidant such asfree chlorine or permanganate to oxidize the arsenic.This article highlights an Ohio treatment plant wherenatural bacteria in the source water concentrate infilters and oxidize As(III), eliminating the need for astrong oxidant ahead of filtration. Microbial filtrationalso provides secondary benefits such as reduced chemical-handling issues, maintenance of nitrification capacityin the filters, elimination of nitrification potential inthe distribution system, and reduced chlorine demandin the finished water.Microbial treatment of drinking water is not widelyaccepted in the United States. Results of this researchdemonstrated that As(III) oxidation and its subsequentremoval can occur microbially, offering an alternative,nonchemical approach to As(III) oxidation and a safeand relatively simple means of meeting the arsenicdrinking water standard. Includes 43 references, tables, figures.

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Edition: Vol. 99 - No. 12 Published: 12/01/2007 Number of Pages: 15 File Size: 1 file , 390 KB