A critical review of recent advances in the bio-remediation of chlorinated substances by microbial dechlorinators

Abstract

A significant health risk is associated with chlorinated hydrocarbon contamination in soils and groundwater. Microbial reductive dechlorination, one of the major pathways of chlorinated hydrocarbon degradation, has been extensively studied in anaerobic subsurface environments. The current study presents a comprehensive review and advancement related to the enhanced in-situ reductive dechlorination of chloroethenes, polychlorinated biphenyls, and chloroethenes in the recent past. Reductive dechlorination is an important pathway for dechlorination in an anaerobic environment performed by a wide group of fermentative, methanogenic, iron, and sulfate-reducing microbial populations for complete degradation of chloroethenes. Presently, the most widely used biotic remediation technologies are based on functional anaerobic bacteria. Although this technology can be used in treating hazardous contaminants yet, the problem surfaces when natural electron acceptors such as nitrates, sulphates, and bicarbonates compete with the target contaminants for electrons. Therefore, in order to accurately evaluate the effectiveness of this technology under natural hydro-chemical conditions, a thorough mechanistic overview of electron competition and electron selectivity is critical to understanding the mechanisms governing these phenomena. This review aims to provide an overview of functional microbes in eliciting in-situ biostimulation or bioaugmentation strategies that can be implemented in future research studies pertaining to this domain.

Keywords

• Bioremediation
• Dechlorination
• Chlorinated hydrocarbons
• Anaerobic & aerobic
• Dehalococcoide
• Bio-stimulation & augmentation