Simulation of combined anaerobic/aerobic bioremediation of tetrachloroethylene in groundwater by a column system

Abstract

Chlorinated aliphatic hydrocarbons generally cannot be used as the carbon source or energy source for microorganism growth; these compounds are more difficult to be biodegraded by microorganisms in groundwater. The objective of this study was to explore the growth and degradation capability of aerobic mixed culture in a sand column simulating a PCE and DEC-contaminated aquifer. Results of the biostimulation study indicated that DCE removal rate was 60% after the operation of 56 days. With the bioaugmentation of aerobic mixed culture, DCE removal rate could be enhanced by 100% in the upstream of a simulated aerobic aquifer after the operation of 105 days. Bioremediation was conducted by addition of mixed aerobic bacteria that can degrade dichloroethylene to investigate the biodegradation of dichloroethylene in a simulated anaerobic and aerobic groundwater system. The results of column tests show that the pollutants in the downstream of the simulated anaerobic aquifer mainly comprised dichloroethylene, vinyl chloride, and methane. Fourteen days after mixed aerobic bacteria were added to the simulated aerobic aquifer, the removal efficiency of most intermediates generated from the anaerobic biodegradation process reached approximately 99%, indicating that the combined anaerobic-aerobic system accelerated the degradation of tetrachloroethylene and dichloroethylene.