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Riverbank filtration (RBF) has been recommendedas a treatment process to remove Cryptosporidiumparvum in surface waters. A comprehensive studywas undertaken in southwestern Ohio to investigateseveral aspects of RBF, specifically the effects of infiltration,streambed scour, and high river-stage frequencieson RBF efficiency and potential breakthrough ofpathogens.During periods of high river stage and flow, scourof the streambed (e.g., removal of the fine-grainedsediments on the bottom of a river) may occur. Scourhas been thought to reduce the filtration capability ofan RBF system, and the US Environmental ProtectionAgency has held that scour of the streambed at RBFsites is problematic. In other words, if the streambedis removed, the system becomes vulnerable to breakthroughby Cryptosporidium and other pathogenicprotozoa. This study, undertaken in part to investigatethis concern, found no direct evidence that scouroccurred at any degree of magnitude at this site orhad any adverse effect on water quality. In addition,this work examined variations in the rate of infiltrationof surface water caused by high river-stageevents and found that the frequency of occurrence forhigh-infiltration periods was low. Results indicatedthat the streambed and aquifer were able to bufferwater quality effects from major increases in the infiltrationrate.Until now, these significant issues surrounding RBFhad not been fully investigated and were only partiallyunderstood. This research should help build confidencein RBF as an important treatment tool that can helputilities comply with the Surface Water Treatment Ruleand other regulations. Includes 21 references, figures.

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Edition: Vol. 96 - No. 12 Published: 12/01/2004 Number of Pages: 13File Size: 1 file , 550 KB