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CHARACTERIZING THE EFFECT OF CHLORINE AND CHLORAMINES ON THE FORMATION OF BIOFILM IN A SIMULATED DRINKING WATER DISTRIBUTION SYSTEM
Citation:
Clark*, R M. AND M Sivaganesan*. CHARACTERIZING THE EFFECT OF CHLORINE AND CHLORAMINES ON THE FORMATION OF BIOFILM IN A SIMULATED DRINKING WATER DISTRIBUTION SYSTEM. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-01/024 (NTIS PB2001-105532), 2001.
Impact/Purpose:
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Description:
Drinking wate treatment in the US has played a major role in protecting public health through the reduction of wateborne disease. However, carcinogenic and toxic contaminants continue to threaten the quality of surface and ground water in the US. The passage of the Safe Drinking Water Act of 1974 and the subsequent amendments reflect this concern. The SDWA and its Amendments have been interpreted as meaning that some Maximum Contaminant Levels (MCLs) promulgated under the Act shall be met at the consumers tap, which in turn, has forced the inclusion of entire distribution system when considering compliance with a number of the Act's MCLs, Rules and Regulations. The Surface Water Treatment Rule which was promulgated under the Act requires that detectable disinfectant be maintained at representative locations in the distribution system to provide protection from microbial contamination and to maintain water quality in the distribution system. One aspect of maintaining water quality in drinking water distribution systems is controlling biofilm on distribution system pipe walls. Investigators have demonstrated the occurrence of high concentrations of bacteria in tubercles that exist in water mains, especially unlined cast iron mains, and on various types of pipe surfaces. A study was conducted jointly by the USEPA and the University of Nancy, France to examine the control of microorganisms in treated water and at the pipe wall. A special pilot facility was constructed in which finished water from parallel water treatment pilot plants was discharged into pipe loops that contained sample tap locations to facilitate biofilm sampling. The facility was utilized to compare the effects of post-chlorination and post-chloramination on the concentration of microorganisms in the bulk phase and at the pipe wall. The analysis utilized in this study characterizes these effects as measured by direct count epifluorescence, and cultural techniques. It found that chlorine is as effective or more effective in reducing the concentration of microorganisms in the bulk phase and in controlling biofilms at the pipe wall.