EFFECTS OF CARBON SOURCE AMENDMENT ON THE ANAEROBIC DEGRADATION OF 1,1,1-TRICHLOROETHANE (TCA) IN A CONTAMINATED AQUIFER

摘要

We conducted a 10-month anaerobic microcosm test and a 15-month field test to investigate the effects of carbon source addition on the in-situ 1,1,1-trichloroethane (TCA) degradation in a polluted aquifer at an industrial site near Antwerp, Belgium. In the microcosms TCA decreased from 15000 μg/L to 1500 μg/L. 1,1-Dichloroethane (DCA) end-concentrations were about the same as the concentrations at the start of the tests (1500 μg/L). 1,1-Dichloroethene (DCE) decreased from 1200 μg/L to 800 μg/L. Carbon source unamended and amended microcosms showed equal concentration trends. Neither chloroethane (CA) nor vinyl chloride (VC) were produced in the microcosms. In the field test TCA dropped from 15000 μg/L to below 2000 μg/L. Upstream, TCA levels remained elevated proving that the C-source injection had stimulated degradation. Sulphate reducing bacteria were stimulated; FeS was produced in the microcosms and aquifer. Dehalococcoides species were stimulated in some microcosms and in the HRC-amended aquifer. Neither sulphate reducers nor Dehalococcoides species are however believed to be responsible for the observed TCA degradation. The carbon source injection however did yield environmental conditions that increased TCA degradation.