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Particulate Arsenic Release in a Drinking Water Distribution System
Citation:
LYTLE, D. A., T. J. SORG, C. MUHLEN, AND L. Wang. Particulate Arsenic Release in a Drinking Water Distribution System . Journal AWWA. American Water Works Association, Denver, CO, 102(3):87-98, (2010).
Impact/Purpose:
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Description:
Trace contaminants, such as arsenic, have been shown to accumulate in solids found in drinking water distribution systems. The obvious concern is that the contaminants in these solids could be released back into the water resulting in elevated levels in a consumer’s tap water. The objective of this study was to identify and evaluate the source of high arsenic in the consumer’s tap water of a small drinking water system having chlorination and polyphosphate addition for iron precipitation control, and to evaluate the effect of the installation of an iron/arsenic removal treatment system. Before treatment, first draw and flushed samples collected from a number of home taps found high arsenic concentrations (as high as 299 μg/L) that were attributable to iron solids found in the distribution system. Arsenic concentrations in first draw water samples were greater than arsenic levels in water entering the distribution system in 29 percent of the tap water samples, and always greater than corresponding flushed samples. Arsenic was determined to be in the particulate form bound to iron particles carried over from the source water. Color measurements were good predictors of arsenic and iron levels in the tap water, and turbidity was a relatively poor predictive measurement. After treatment, the arsenic was reduced to less than 1 μg/L.
