CONCOMITANT AEROBIC BIODEGRADATION OF BENZENE AND THIOPHENE

The concomitant aerobic biodegradation of benzene and thiophene was in vestigated in microcosm experiments using a grounds ater enrichment cu lture. Benzene was biodegraded within 1 d, whereas thiophene could not be biodegraded as the sole source of carbon and energy. Some interest ing phenomena were observed when both benzene and thiophene were prese nt. In most cases, removal of thiophene was observed, and the removal occurred concomitantly with the biodegradation of benzene, suggesting that benzene was used as a primary substrate in the cometabolic biodeg radation of thiophene. No biodegradation of the two compounds was obse rved for some combinations of concentrations, suggesting that thiophen e could act as an inhibitor to benzene biodegradation. However. this e ffect could be overcome if more benzene was added to the microcosm. Re sidual concentrations of benzene and thiophene were observed in some m icrocosms and the data indicated that the biodegradation of the two co mpounds stopped when a critical threshold ratio between the concentrat ions of thiophene and benzene was reached. This ratio varied between 1 0 and 20. Results from modeling the biodegradation data suggested that thiophene was cometabolized concomitantly with the biodegradation of benzene and that the biodegradation may be described by a modified mod el based on a traditional model with an inhibition term incorporated.