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Tailored granular activated carbon (GAC) can reduce groundwater perchlorate levels from 60-80ug/L to below detection. Specifically, rapid small-scale column tests, also called RSSCTs,showed that by preloading GAC with iron-oxalic acid, the GAC adsorption capacity could beimproved up to 42%. When the preloaded GAC became saturated with perchlorate, 65-74%of the GAC's original adsorption capacity could be restored by chemically regenerating the GACwith sodium borohydride. This chemical regeneration could be achieved with the use of asmall fraction of the water that had been processed during the water treatment cycle. The wastestream from chemical regeneration contained concentrated perchlorate levels as high as7,000-15,000 ug/L. With this approach, the simulations described in this article indicated thatwhen two tailored GAC beds were operated in series with a 40-min empty-bed contact time,they could provide water treatment service for 60-75 days during the first operations cycle;following chemical regeneration, the GAC beds could provide about an additional 30-40 daysof water service for several successive treatment and regeneration cycles. Includes 29 references, tables, figures.

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Edition: Vol. 94 - No. 11 Published: 11/01/2002 Number of Pages: 13File Size: 1 file , 310 KB