Use of Bioaugmentation To Stimulate Complete Reductive Dechlorination of Trichloroethene in Dover Soil Columns

Abstract

Soil columns were constructed in support of the Remediation Technologies Development Forum accelerated biodegradation study at Dover Air Force Base to evaluate the impact of amendments on the anaerobic reductive dechlorination of trichloroethene (TCE) in Dover soil. Dechlorination of TCE to cis-dichloroethene (c-DCE) was observed in the columns using lactate, lactate and methanol, butyrate, glutamate and 1,2-propanediol, or toluene as electron donors, in combination with vitamins and other supplemental nutrients. However, the c-DCE formed was not further dechlorinated using any of these amendments. Subsequent inoculation of two columns with a competent, non-native TCE-dechlorinating culture resulted in the dechlorination of TCE to ethene after 30 days. Once the culture was established, dechlorination of TCE to ethene was complete in the first several centimeters of the columns at TCE influent concentrations of 4 mg/L. The culture was also able to dechlorinate TCE to ethene when TCE influent concentrations were increased to 170 mg/L. These results suggest that a critical bacterial population was missing in these soils and that bioaugmentation is an appropriate remedial strategy under such circumstances.