Anaerobic Reductive Dechlorination of Tetrachloroethylene (PCE) in Two-in-series Semi-continuous Soil Columns

GreenTech Environmental Consulting Co. Ltd. Anaerobic reductive dechlorination of tetrachloroethylene (PCE) to ethylene was investigated by performing laboratory experiments using semi-continuous flow two-in-series soil columns. The columns were packed with soils obtained from TCE-contaminated site in Korea. Site ground water containing lactate (as electron donor and/or carbon source) and PCE was pumped into the soil columns. During the first operation with a period of 50 days, injected mass ratio of lactate and PCE was 620:1 and incomplete reductive dechlorination of PCE to cis-DCE was observed in the columns. However, complete dechlorination of PCE to ethylene was observed when the mass ratio increased to 5,050:1 in the second operation, suggesting that the electron donor might be limited during the first operation period. Dechlorination rate of PCE to cis-DCE was 0.62~1.94 µmol PCE/L pore volume/d and 2.76 µmol cis-DCE / L pore volume/d for that for cis-DCE to ethylene, resulting that net dechlorination rate in the system was 1.43 umol PCE/L pore volume/d. During the degradation of cis-DCE to ethylene, the concentration of hydrogen in column groundwater was 22~29 mM and 10~64 mM for the degradation of PCE to cis-DCE. These positive results indicate that the TCE-contaminated groundwater investigated in this study could be remediated through in-situ biological anaerobic reductive