PREVENTION OF ODOR PRODUCTION AND RELEASE IN MUNICIPAL WASTEWATER COLLECTION SYSTEMS RESULTING FROM SEPARATION OF COMBINED SEWER SYSTEMS

Several municipalities in the Untied States and Canada have separated, or are in the process of separating, their combined sewer outfalls (CSOs) into separate sanitary and storm sewer collection networks. This practice has been primarily driven by regulatory requirements to reduce the number and frequency of combined system overflows into streams and other waterways. There is no doubt that CSO separation has had a positive impact on water quality and wildlife, however; it can lead to an increase in sanitary sewer pressurization and subsequent odor release if proper care is not taken during the design of separation facilities. Experience in several municipalities has shown that the criteria upon which engineers rely often fails to include wastewater odor production effects and the ventilation dynamics of such a change. This paper presents observations and causes of increased odor production and release in recently separated collection systems and presents corrective actions which have been shown to reduce these odor effects.