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ARSENIC DESORPTION FROM DISTRIBUTION SYSTEM SOLIDS
Citation:
Lytle*, D A. AND R. Copeland. ARSENIC DESORPTION FROM DISTRIBUTION SYSTEM SOLIDS. Presented at WSWRD Peer Review, Cincinnati, OH, September 27 - 29, 2004.
Impact/Purpose:
To inform the public.
Description:
Due to the recent reduction of the maximum contaminant level (MCL)of arsenic, eliminating possible human exposure has become increasingly critical. Research has suggested that consumer taps could be a likely source of human exposure to this harmful element. This is due to arsenic that is adsorbed onto distribution system solids. The main objectives of this research are to better understand arsenic desorption from different distribution solids and to define the water quality parameters that have the greatest impact on desorption. This information will help predict when to expect desorption, and improve understanding of the degree of potential exposure. Additionally, it will also help to develop ways in which to control arsenic release from drinking water distribution systems. It was determined that arsenic can desorb from drinking water distribution solids in test waters in the pH ranges tested (6-9). The concentrations of arsenic release depended on pH and the amount of arsenic present on the solid initially. At higher pH values more arsenic re-entered the test water. Future experiments will be conducted determining if phosphate and sulfate enhance desorption from distribution system solids. In addition, leaching of the media will be done until exhaustion to better understand the kinetics and extent of arsenic release.