AWWA ACE54494

The major drawback to the use of ion exchange for removal of arsenate from potable water is that other ions, especially sulfate, successfully compete with the arsenate for exchange sites. We investigated a novel approach for operating such a process in which an arsenic-rich zone is semi-permanently retained in the operating columns, so that only sulfate-rich resin is regenerated. In this way, essentially all the arsenic fed to the system was retained during treatment of >36,000 bed volumes of influent. The precipitation of CaSO4 or BaSO4 from the brine and the subsequent reuse of the brine solution was also studied. Overall, the combination of modified column operation and brine recovery can dramatically reduce the costs associated with arsenic treatment by ion exchange. Includes figures.