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High-Rate Disinfection Techniques for Combined Sewer Overflow (Proceedings Paper)
STINSON, M. K., I. WOJTENKO, AND R. FIELD. High-Rate Disinfection Techniques for Combined Sewer Overflow (Proceedings Paper). In Proceedings, WRPMD 1999 — Preparing for the 21st Century; Annual Water Resources Planning and Management Conference, Tempe, AZ, June 06 - 09, 1999. American Society of Civil Engineers (ASCE), Reston, VA, 102(40430):200, (1999).
To inform the public
This paper presents high-rate disinfection technologies for combined sewer overflow (CSO). The high-rate disinfection technologies of interest are: chlorination/dechlorination, ultraviolet light irradiation (UV), chlorine dioxide (ClO2 ), ozone (O3), peracetic acid (CH3COOOH ), and high-voltage electron beam irradiation (E-Beam). Discussions of the technologies include: commercial availability and extent of use, state of development when not commercial, and, where available, performance data and cost of either full-scale or pilot-scale installation. Discussed also is utility of increased mixing in concert with any disinfection technology. Disinfection of CSO is generally practiced to control the discharge of pathogens into receiving waters. Therefore, the disinfectant used at a facility for treatment of CSO should be adaptable to intermittent use. Other considerations include effectiveness, oxidation rate, safety, and cost. Commonly used disinfection by chlorination forms toxic residual by-products. Newer disinfectants such as UV, ClO2, O3, CH3COOOH, and E-Beam may have a far lesser potential to generate toxic byproducts. Since CSO flowrates and volumes are significantly greater than dry weather flows, use of high-rate processes requiring less tankage and space is more cost-effective than use of conventional processes. The high-rate disinfection can be accomplished by: (1) applying mixing intensity, (2) increasing disinfectant concentration, (3) using faster acting oxidants, (4) using high-energy irradiation, or (5) using combinations of these. Use of increased mixing with any disinfection technology provides better dispersion of the disinfectant and forces disinfectant contact with a greater number of microorganisms per unit time. The increased rate of collisions decreases the required contact time, which enables a high-rate disinfection.