EVALUATING CAPACITIES OF GAC PRELOADED WITH NATURAL-WATER

Adsorption studies are conducted to determine how preloading a natural groundwater onto GAC affects the adsorption of cis-1,2-dichloroethene in small-scale and pilot-scale columns. Capacities are determined from batch-isotherm tests, microcolumns, and pilot columns, which are preloaded for various lengths of time. Breakthrough profiles from short-bed adsorbers and pilot columns provides information regarding the kinetics of adsorption. Some of the results are: adsorption capacity and kinetic rate decreases with increasing time of preloading, the preloaded microcolumns show capacity reductions similar to that of the preloaded pilot columns, and preloaded column capacities are represented well by preloaded isotherms. The reduction in pilot-column capacity due to preloading for cis-1,2-dichloroethene is shown to be partially offset by using columns in series where the columns are only added when needed to contain the mass-transfer zone. For cis-1,2-dichloroethene, the increased run time due to adding columns may not be worthwhile in field applications, unless extensive preloading occurs before the contaminant arrives at the column.