AWWA JAW61902

Because of byproducts from algal blooms (e.g., 2- methylisoborneol [MIB] and geosmin), many water utilities struggle to provide aesthetically pleasing water. Most utilities choose to combat these taste and odor episodes by dosing powdered activated carbon (PAC) at the beginning of their treatment process because it is relatively inexpensive, easy to dose, and requires little maintenance. However, this practice can have several deficiencies, rendering it less effective for MIB removal. Few studies have been conducted on the use of commercially available granular activated carbon (GAC) as a cost-effective, plausible treatment technology for ensuring that customers receive potable and palatable water. No papers compare various commercially available carbons for their ability to adequately retain MIB once the odor episode ceases. Thus, because GAC avoids the problems cited with PAC addition, the purpose of this study was to compare the performance of various activated carbons, both virgin and reactivated, to determine whether GAC offers a plausible strategy for combating taste and odor episodes. Rapid small-scale column tests were used to compare virgin, conventionally reactivated, and steam pyrolysis-reactivated GACs for their performance in removing MIB and for their ability to retain MIB when the odor episode subsided. Two clarified waters were used to compare the differences in GAC performance for MIB removal when in competition with differing concentrations of total organic carbon. Although the virgin wood-based GAC processed more bed volumes before initial breakthrough and before surpassing the odor threshold concentration than did the coal-based virgin GACs, its affinity for MIB when the odor episode subsided was the weakest. However, the physically activated and reactivated carbons had excellent affinities for MIB after the odor episode concluded. Includes 29 references, tables, figures.