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Water Intelligence Online © IWA Publishing 2004


J. Sandino

Black & Veatch, 8400 Ward Parkway, Kansas City, Missouri, 64114, USA


Physical-chemical treatment of wastewater originated in the 18th century, and was widely relied upon in the late 19th and early 20th centuries as part of sanitation schemes for municipal areas. The high cost of handling and disposing the large amounts of sludge produced, and the advent of stricter effluent requirements resulted in the abandoning of this process for systems that relied on a biological treatment step. In recent years however, chemically enhanced primary treatment (CEPT), a variation of the early process that relies on considerably lower dosages of chemicals, has found applicability in large-scale treatment solutions in which high seasonal hydraulic loading variations are experienced; where there is limited space availability; and where the characteristics of the receiving stream require treatment levels higher than primary, but not quite as stringent as secondary. More recently, CEPT has been receiving considerable attention given its ability to remove phosphorus, a macronutrient associated with eutrophication problems in some receiving water bodies. Also, incorporating chemical addition to primary clarifiers is being used to increase existing treatment capacities (e.g. higher hydraulic throughput rates; higher removal efficiencies) as well as for reducing the influent loads to subsequent biological treatment stages in facilities required to meet more stringent standards. Treatment plants in cities like Hong Kong, Montreal, Los Angeles, and Rio de Janeiro have adopted this process. This paper presents a brief history of CEPT, discusses its technical features, and presents an economic evaluation of different ways in which this process can be integrated to large-scale wastewater treatment applications.

Full article (PDF Format)

UNIQUE ID: 200408018

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