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Disinfection is often considered the most critical step in any drinking water treatment process (Trussel,1999; LeChevallier, 1999). Secondary disinfection is the primary mitigation step used by utilities tocontrol microbiological growth in distribution systems. Currently, the US Environmental Protection Agency (USEPA) requires that a residual of0.2 mg/ L disinfectant residual be maintained at the entry point of a distribution system (FederalRegister document #52 FR 42199). Research has shown that microorganisms can survive in distributionsystems despite the continuing presence of disinfectants (e.g., Pryor et al., 2003; Chauret et al., 2001),therefore placing doubt on the ability of a disinfectant residual to ensure microbial protection fromevents such as breeches in distribution integrity. It has been shown that a residual of 0.2 mg/L limits thegrowth of heterotrophic bacteria in the distribution system; however there is limited data that canidentify the appropriate amount of disinfectant required to inactivate known pathogens in distributionsystems such as E. coli.The focus of this project was to investigate the anti-microbial resistance of E. coli in disinfectedannular reactors (ARs) that were operated under conditions relevant to drinking water distributionsystems. In addition, this work compared the potential synergies of ultraviolet (UV) treatment and disinfection on E.coli in distribution systems. For comparative purposes, both cast iron and polycarbonate ARs were usedto compare disinfectant efficacy on different pipe material. Additionally, three disinfectants wereexamined during separate AR trials (Clsub2/sub, ClOsub2/sub, and NHsub2/subCl). Includes 7 references.

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Edition: Vol. - No. Published: 06/01/2006 Number of Pages: 5File Size: 1 file , 230 KB