Full Description

Granular activated carbon (GAC), although relatively expensive,is used extensively to treat drinking water in both theUnited States and the United Kingdom. However, GAC hasa finite capacity to adsorb pollutants. Once this capacity isreached, it must be replaced with new GAC or the GAC must berecovered by thermal regeneration in a furnace and reused.This paper summarizes the most common GAC regenerationprocesses and the consequences of using these processes, includingthe likely cause of many phenomena observed by utility managersin water treated by regenerated GAC, e.g., high aluminum,high pH, and sulfide tastes and odors. Inorganic salts adsorbedduring treatment catalyze oxidation reactions when the GAC isregenerated and lead to deterioration of its adsorbent properties.The authors found that acid-washing spent GAC adsorbentsbefore thermal regeneration removes accumulated metals,particularly calcium, and significantly improves the GAC's adsorbentproperties over thermal regeneration alone. This articleshould help water utility managers modify their GAC regenerationpractices to combat the problems caused by adsorbed inorganiccompounds. Includes 57 references, table, figure.

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Edition: Vol. 94 - No. 12 Published: 12/01/2002 Number of Pages: 11File Size: 1 file , 480 KB