EFFECTS OF ELECTRON-DONOR AND MICROBIAL CONCENTRATION ON THE ENHANCEDDECHLORINATION OF CARBON-TETRACHLORIDE BY ANAEROBIC CONSORTIA

Reductive dechlorination of carbon tetrachloride (CCl4) by anaerobic b acterial communities from anaerobic digester sludge with the amendment of low concentrations of electron donors and microorganisms was under taken to evaluate the influence of electron donors and microbial conce ntration on the rate of dechlorination of CCl4. Humic acid, acetate, a nd glucose were selected to examine the feasibility of the electron do nor with respect to the remediation of a contaminated subsurface. The addition of an electron donor and microorganisms significantly enhance d the dechlorination rate of carbon tetrachloride. The addition of an electron donor increased the cell numbers of anaerobic consortia, ther eby increasing the rate of dechlorination. Glucose was a better electr on donor than acetate and humic acid under reducing environments. The pseudo-first-order degradation rate constants of CCl4 ranged from 0.00 57 day(-1) to 0.135 day(-1), depending on the conditions of the electr on donor and biomass supplemented. Furthermore, the addition of the el ectron donor in the batches amended with 0.56 mg volatile suspended so lids (VSS)/l biomass had a higher enhanced efficiency than those with 1.7 mg VSS/l biomass. These results suggest that there is a potential for stimulating the dechlorinating capability of anaerobic consortia t o remedy the chlorinated hydrocarbons in the oligotrophic environment if the conditions of the supplementing electron donor are properly sel ected.