Degradation of 1,1,1-Trichloroethane in Bench-Scale Bioreactors

Abstract

Microbial degradation of 1,1,1-trichloroethane (TCA) was demonstrated in packed bed laboratory reactors. Bioreactor columns were packed with sandy clay loam, extended with a small fraction of granular activated carbon, designed to simulate an in-situ decontamination system. Columns were seeded with an acclimated, mixed microbial stock culture, developed for anaerobic response experiments. A surface feed was used to support an aerobic community in the upper sections of the reactor. This upper zone consumed diffusing oxygen and reduced evaporative losses of sorbent. A sub-surface feed introduced contaminated groundwater, nutrients and supplementary carbon (ethanol) into the lower, anaerobic reaction zones. TCA appeared in column effluents infrequently, but was not detected after Day 47 of operation. Experiments were terminated after 112 days. With sorption controlling, saturation and complete break-through should have occurred in about 43 days.