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HIGH-RATE DISINFECTION OF COMBINED SEWER OVERFLOW
Citation:
Wojtenko**, I, M K. Stinson*, AND R Field*. HIGH-RATE DISINFECTION OF COMBINED SEWER OVERFLOW. Presented at 9th International Conference on Urban Drainage, Portland, OR, 09/08-13/2002.
Description:
Wet-weather flow (WWF), including combined-sewer overflow (CSO, sanitary-sewer overflow, and stormwater (SW), is a significant contributor of microbial contamination to surface water and ground water. By using effective wastewater or SW disinfection, introduction of pathogen contamination into receiving waters can be greatly minimized. CSO flowrates and volumes are significantly greater than those of dry-weather flow. The characteristics of CSO (e.g., flowrates, high suspended solids and pollutant content, variable temperature, and microorganisms) make it difficult to disinfect. Disinfection techniques need to be high-rate with strong microbe-killing capabilities. They must be adaptable (effective under varying conditions) and be able to achieve at least a three log (99.9%) reduction of target microorganisms. the most comonly used disinfecting agent is chlorine. Because of the high flowrates and volumes of CSO, its effective disinfection requires high chlorine dosing that results in a high level of toxic byproducts. Due to its effect on aquatic ecosystems, alternative disinfection processes are being investigated. The introduction of new disinfecting agents for lower-quality wastewater such as CSO has proven to be very difficult. Disinfection processes for such applications should be adaptable to use under dry and WWF conditions. Alternative disinfection technologies for CSO discussed in this paper are: ultraviolet irradiation, chlorine dioxide, and ozonation.