Bioaugmentation-assisted bioremediation and biodegradation mechanisms for PCB in contaminated environments: A review on sustainable clean-up technologies

This review aims to give a detailed overview of various bioremediation technologies used for the decontamination of polychlorinated biphenyl (PCB)-polluted environments; discuss the bioaugmentation approaches employed to treat PCB-polluted soil, sediment, and wastewater; explore the limitations of bioaugmentation and the strategies to improve its efficiency; give an update on the current state of biodegradation studies on PCB and their mechanisms; explore the future research prospects on bioremediation based on the articles discussed in the current review. Extensive analysis of original works has revealed that the various bioremediation strategies displayed varying efficiencies with most found to be efficient. Coupling of treatment methods has been found effective in the decontamination of polluted sites. The biodegradation of PCB revealed that the concentrations of highly-chlorinated PCB can be substantially reduced under sequential anaerobic and aerobic processes. The study revealed that the concentrations of PCB in contaminated media declined largely due to the degradation of congeners with one or more chlorine atoms. Various enzymes participated in the degradation of PCB and include multicomponent dioxygenase (bphA, E, F, and G), dehydrogenases (bphB), second dioxygenase (bphC), and hydrolase (bphD). The review provides novel biological treatment strategies for the management of PCB-contaminated sites.