AWWA QTC97091

The R.C. Willson Water Treatment Plant is a conventional WTP operated by the City of Hagerstown, Maryland. The plant treats water withdrawn from the Potomac River and directly recycles the spent filter backwash water to the plant influent. Some treatment of the recycled filter backwash is provided by presedimentation prior to coagulation. Recently, however, both the US Environmental Protection Agency and the Maryland Department of the Environment (MDE) have expressed concern about the potential negative microbial impacts of recycling filter backwash water. The main objectives of this study were to: investigate the filter backwash wastewater recycle impacts on the efficiency of particle removal; evaluate the adequacy of the existing recycle system based on the standards established by the MDE; determine the impacts on plant influent quality from the reuse of filter backwash wastewater; and, determine the effectiveness of the presedimentation basins for equalizing and removing particles and turbidity from the filter backwash wastewater.