Aerobic biodegradation of a mixture of chlorinated organics in contaminated water

The environmental persistence, toxicity and/or carcinogenicity of chlorinated aliphatic compounds (CAHs) and their potential for bioaccumulation in food chains has made them of serious environmental concern. The frequency of a mixture of these compounds encountered in most contaminated sites has warranted investigation into their fate in contaminated sites. In this study, therefore, the biodegradation of a mixture of CAHs; namely, carbon tetrachloride (CCl4), 1,2-dichloroethane (DCA) and dichloromethane (DCM), in contaminated water microcosms was investigated. The mixture of CAHs investigated was observed to be simultaneously degraded in both microcosms with up to 86.28% CCl4, 44.64% DCM and 52.34% DCA degradation observed in the untreated microcosms. The degradation rate constants of the CAHs ranged variously between 0.168 – 1.234 week-1 for CCl4; 0.175 – 0.832 week-1 for DCM; and 0.232 – 0.588 week-1 for DCA in both water microcosms with higher degradation generally observed in New Germany Wastewater compared to those in Northern Wastewater. Findings from this study also suggest that biostimulation and/or bioaugmentation is required to speed up the biodegradation process, depending on the available nutrients and the presence or absence of microbial population capable of CAHs’ metabolism at the contaminated sites.