AWWA JAW41459

Water filtration plants treating surface water sources can be expected to routinely produce finished water of excellent quality when the source water quality remains steady or changes slowly. When the quality of the source water changes drastically over short periods, however, treatment plants may face severe challenges. Such a situation occurred at the Decatur, Illinois, South Water Treatment Plant early in 1994. After a high-turbidity episode, the lime-softening plant experienced buildup of coagulant and calcium carbonate deposits in the filter beds. The filters and the deposits were evaluated, and an in situ filter media cleaning technique was successfully applied, using glacial acetic acid. Includes 4 references, table, figure.