Coupling in situ chemical oxidation with bioremediation of chloroethenes: a review

Contamination by chloroethenes represents serious risks to both the environment and human life due to their toxic and sometimes carcinogenic effects. Coupling in situ chemical oxidation (ISCO) and in situ bioremediation (ISB) approaches to clean the sites contaminated by chloroethenes is increasingly being considered as a biphasic technology. Successful implementation of ISB after ISCO, however, requires an understanding of ISCO effects on indigenous microbial population responsible for biodegradation. This review focuses on interactions between three main ISCO approaches and microbial populations in chloroethenes contaminated subsurface. Chloroethenes toxicity and fate in the subsurface have also been discussed. The review further summarizes ISCO and microbial strategies for chloroethenes remediation. Indigenous microbial degrading capacity, especially the anaerobic step, may be damaged by aggressive conditions that are required for successful ISCO treatment. Therefore, the impact of oxidation agents on soil geochemistry and bioprocesses have been investigated. The review also provides up-to date summary in coupled ISCO and ISB for chloroethenes remediation. Finally, future research needs are proposed to optimize the application of this biphasic technology for the chloroethenes contaminated sites remediation. Graphic abstract