Combined Sewer Overflow Treatment

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Contribution to Books

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Publication Title

Handbook of Environment and Waste Management: Air and Water Pollution Control


© 2012 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. Combined sewer overflow (CSO) normally occurs when the stormwater flow exceeds the hydraulic capacity of the combined sewer systems (CSS). The latter is a system comprising of sanitary wastewater and stormwater runoff. CSO needs to be treated properly because CSOs typically discharge a variable mixture of raw sewage, watershed runoff pollutants and scoured materials that build up in the collection system during dry weather periods. These discharges contain pollutants that may adversely impact the receiving water body. Most conventional CSO treatment is by chlorine disinfection, but there are also alternative disinfection method such as ozonation, ultraviolet (UV) radiation, peracetic acid and electron beam irradiation.