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Impact of Arsenic Treatment Systems on Distribution System Water
Citation:
SORG, T. J., A. Chen, L. Wang, AND D. A. LYTLE. Impact of Arsenic Treatment Systems on Distribution System Water . Presented at AWWA Distribution Systems Symposium, Nashville, TN, September 11 - 14, 2011.
Impact/Purpose:
To inform the public.
Description:
Under the USEPA Arsenic Demonstration Program, 50 arsenic removal treatment systems were installed and their performance evaluated over a period of one to three years. The program was limited to small systems whose population served were less than 10,000. Ten of the systems were non-transient, non-community water supplies, such as schools. The technologies installed consisted of adsorptive media, iron removal, coagulation filtration, ion exchange and reverse osmosis. Because of an interest and the concern for water quality changes in the distribution water, distribution water samples were collected at each site and analyzed for arsenic, lead, copper, iron and manganese at three locations in the distribution system impacted by the treatment systems during the studies. With lead and copper being the main issue, the water systems were requested to select sample locations that were normally used for their lead and copper monitoring program. The sampling procedures followed were also those used for lead and copper sampling. To evaluate the impact of the treatment systems on the distribution water, sampling at the selected sites started one to four months before the treatment systems were installed to provide baseline data. The presentation will present the water quality data on the distribution water before and after the arsenic treatment systems were install. The information will focus mainly on lead, copper and arsenic and broken down by the type of treatment installed. The data from these studies showed that the treated water from all of the arsenic removal processes had little or no effect on the lead and copper levels in the distribution system water and as expected the arsenic levels, in most cases, were similar to the arsenic levels of the treated water. At some sites, however, the arsenic levels of the distribution water was slightly above the treated water suggesting that arsenic was desorbing from distribution system pipe surfaces. The results of these studies indicate that the concerns raised (in several JAWWA papers) over the possible increases in lead and copper levels in the distribution water caused by new arsenic removal treatment systems may not be a major problem.