Citation:

Wojtenko**, I, M K. Stinson*, AND R Field*. USEPA CAPSTONE REPORT: DISINFECTION. Presented at Firth Inernational Conference: Diffuse/Nonpoint Pollution and Watershed Management, Milwaukee, WI, June 01 - 15, 2001.

Impact/Purpose:

To inform the public.

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. Contamination with human-origin fecal coliform (FC) is of great concern for sanitary sewer systems. Contamination with FC of nonhuman-origin (other warm-blooded organisms) is the major concern for SW systems. In combined-sewer and storm-drainage systems having unauthorized sanitary wastewater connections, fecal contamination of both human- and nonhuman-origin are of concern. By using effective wastewater or SW disinfection, introduction of fecal and pathogen contamination into receiving waters can be greatly minimized. CSO flowrates and volumes are significantly greater than those of dry-weather flow. Techniques used for CSO disinfection need to be high-rate with strong microbe-killing capabilities. Characteristics of CSO, such as high flowrates, high suspended solids and pollutant content as well as variable temperature and microorganisms make its disinfection difficult. These CSO characteristics require an adaptable disinfection process which would be effective under varying conditions and be able to achieve at least a 3log (99.9%) reduction of target microorganisms. The most commonly used disinfecting agent is chlorine (Cl2). Because of the high flowrates and volumes of CSO, its cost-effective disinfection requires high Cl2 dosing that results in a high level of toxic byproducts. Wastewater disinfection is intended to protect human health, however, disinfection by chlorination is a serious concern due to its effect on aquatic ecosystems providing impetus to finding a replacement. Newer, alternative disinfectants are strong agents which also have a lesser potential to generate toxic byproducts. 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.

Record Details: