Stimulation of the reductive dechlorination of tetrachloroethene in anaerobic aquifer microcosms by the addition of toluene

The possible use of certain alkylbenzenes such as toluene as electron donors in the reductive dechlorination of tetrachloroethene is examined. Evidence from field studies had suggested that this type of reaction might be occurring at sites exposed to both alkylbenzenes and chlorinated solvents. Microcosms constructed with aquifer solids from an area exposed to both were used to investigate the biologically mediated interactions of toluene and tetrachloroethene. After 130 d of incubation, active microcosms spiked with toluene and tetrachloroethene showed a loss of the latter which was not seen in autoclaved controls or in microcosms spiked with tetrachloroethene alone. Overall, the study indicated that toluene could serve as an initial source of reducing potential for the reductive dechlorination of chloroethenes in anaerobic conditions.