Role of electron acceptors and donors in the breakdown of chlorinated hydrocarbons

Soil column experiments were performed to investigate the transformation of chlorinated hydrocarbons in the presence of different electron acceptors or electron donors including NaNO3, Fe(OH)(3), MnO2, or a mixture of volatile fatty acids (VFAs), respectively. The results indicated that 1,2-dichloroethane (1,2-DCA) and vinyl chloride (VC) could be oxidized anaerobically under manganese reducing and denitrifying conditions. Profile measurements in the MnO2-amended column revealed half-lives of 1.3 h for 1,2-DCA, and 4.7 h for VC degradation. Under iron reduction, only 1,2-DCA was degraded. In a control column, without the addition of donors and acceptors, not only 1,2-DCA and VC, but also chlorobenzene (MCB) was removed. In the column supplied with VFAs, sequential reductive dechlorination of tetrachloroethene (PCE) to ethene was observed, and profile measurements revealed that half-lives of PCE, trichloroethene, cis-1,2-dichloroethene and VC were 0.8 h, 1.3 h, 1.6 h and 3.4 h, respectively.