AWWA ACE54427

Perchlorate contaminates groundwater that could potentially be used by 15 million Americans. Much of this contaminated groundwater lies beneath arid regions of the country such as Nevada and southern California. In the summer of 2000, full-scale research was conducted at the Texas Street water treatment plant in Redlands, California. This facility employs granular activated carbon (GAC) to remove perchlorate (along with trichloroethylene and other organics) from the groundwater. The study examined the use of Westates GAC and Westates GAC that had been tailored with iron and oxalic acid. Also examined was the chemical regeneration of GAC using sodium borohydride, sodium hydroxide, and thiosulfate (combined with either calcium or sodium). A two step chemical regeneration process using sodium hydroxide followed by acid treatment was found to recondition the GAC so that it could absorb almost as much perchlorate in a second cycle as it did in a first cycle. Includes figures.