A Cheap Solution to Pollution from Combined-Sewer Overflows

Serial Information: Civil Engineering—ASCE, 1979, Vol. 49, Issue 11, Pg. 83-83

Document Type: Feature article


Every time it rains, the surface waters of many of the older communities around the U.S. are polluted by a mixture of sanitary waste and stormwater. The problem: when the community sewers were installed decades ago, one sewer was used to carry both sanitary wastes and storm waters. The most oft proposed solution is to construct separate storm and sanitary sewers — very costly. But both Lancaster, Pa. and Syracuse, N.Y. have recently tried using a new device that removes many of the pollutants from the stormwater overflows before being discharged to surface waters. Known as the swirl concentrator, this device in Lancaster is basically a cylindrical concrete chamber. The combined-sewer line enters this cylindrical tank tangentially, near the tank bottom. Because of this angle of entry, the wastewater entering the tank has a gentle swirling motion imparted to it, a motion that helps separate solids from the water. EPA considers the swirl cencentrator a promising device that could help many communities address their combined-sewer-overflow problem.

Subject Headings: Stormwater management | Pollution | Combined sewers | Overflow | Surface water | Storm sewers | Cylindrical tanks | Water tanks

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