Granular activated carbon (GAC), although relatively expensive,
is used extensively to treat drinking water in both the
United States and the United Kingdom. However, GAC has
a finite capacity to adsorb pollutants. Once this capacity is
reached, it must be replaced with new GAC or the GAC must be
recovered by thermal regeneration in a furnace and reused.
This paper summarizes the most common GAC regeneration
processes and the consequences of using these processes, including
the likely cause of many phenomena observed by utility managers
in water treated by regenerated GAC, e.g., high aluminum,
high pH, and sulfide tastes and odors. Inorganic salts adsorbed
during treatment catalyze oxidation reactions when the GAC is
regenerated and lead to deterioration of its adsorbent properties.
The authors found that acid-washing spent GAC adsorbents
before thermal regeneration removes accumulated metals,
particularly calcium, and significantly improves the GAC's adsorbent
properties over thermal regeneration alone. This article
should help water utility managers modify their GAC regeneration
practices to combat the problems caused by adsorbed inorganic
compounds. Includes 57 references, table, figure.
| Edition : | Vol. 94 - No. 12 |
| File Size : | 1
file
, 480 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 12/01/2002 |
