Abstract

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.

Key words: Bioaugmentation, biodegradation, biostimulation, chlorinated aliphatic hydrocarbons, microcosms