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Emerging Contaminants in the Drinking Water Cycle
Citation:
GLASSMEYER, S. Emerging Contaminants in the Drinking Water Cycle . Presented at AWWA Alabama-Mississippi Regional Meeting, Montgomery, AL, October 06 - 07, 2008.
Impact/Purpose:
The goal of this project is to determine what happens to potentially hazardous compounds that are commonly found in wastewater and therefore may be present in source waters, as those source waters are subsequently treated for use as drinking water.
Description:
In the past decade, the scientific community and general public have become increasingly aware of the potential for the presence of unregulated, and generally unmonitored contaminants, found at low concentrations (sub-µg/L) in surface, ground and drinking water. The most common pathway for the introduction of these chemicals is from an upstream direct discharge of wastewater effluent. In the US, there are more than two dozen communities that draw their drinking water from streams that consist of more than 50% wastewater during low flow conditions. The US Geological Survey (USGS) and US Environmental Protection Agency (USEPA) have been working on a series of collaborative research projects to determine the identity of chemicals that are commonly present in wastewater effluent, the persistence of these chemicals in surface and ground waters, the removal of these chemicals during drinking water treatment, the formation of by-products during their chlorination and the presence of these chemicals in finished drinking water. In effluents collected at eleven wastewater treatment plants (WWTPs) across the US, 72 out of 110 monitored chemicals were detected at least once, documenting incomplete removal during wastewater treatment. Downstream of the WWTPs, the chemicals exhibited varying environmental persistence. In the source water of one conventional drinking water facility, 45 out of 113 monitored chemicals were detected at least once, with 21 chemicals still detectable in the finished drinking water. This documents the incomplete removal for some chemicals during treatment. In companion laboratory studies on the effects of chlorination, eight of the 14 chemicals investigated were oxidized by the disinfectant, two of which were at least partially chlorinated. Taken as a whole, these studies demonstrate that to understand the comprehensive environmental impact of emerging contaminants, their persistence, removal efficiencies during waste and drinking water treatment, as well as the potential for by-product formation, must be known.