ABSTRACT
Data from the literature and from the Bolivar ASR site were assessed to determine the attenuation of disinfection by-products (DBPs), in particular trihalomethanes (THMs) and haloacetic acids (HAAs), by chemical, microbial and adsorptive processes during ASR. HAAs are readily degraded under both aerobic and anaerobic conditions. Highly reducing conditions are required for effective degradation of all THMs; chloroform is the most recalcitrant with bromoform the most readily degraded. Under less highly reducing conditions, e.g., nitrification, brominated THMs can be degraded. Degradation rates under all reducing conditions increase with the degree of bromine substitution. Under aerobic conditions, THMs are not degraded. Attenuation of both THMs and HAAs by adsorption or chemical hydrolysis appears to be minimal. DBP attenuation at the ASR site reflected what was expected from the literature and demonstrates that different redox zones in the aquifer have a significant effect on THM attenuation rates.
