Promoted reductive removal of chlorinated organic pollutants co-occurring with facilitated methanogenesis in anaerobic environment: A systematic review and meta-analysis

Reductive dechlorination is the most efficient way for depletion of chlorinated organic pollutants (COPs) in anaerobic environment, where the methanogenesis is usually mass-produced. Both processes are essentially microbial-mediated electron accepting processes and received much attention in last decades, due to their great importance for the remediation of environment polluted by COPs, and the effect of global warming as well as biogas property, respectively. In this study, these two reductive processes were comprehensively summarized based on 337 measurements out of 68 articles published from 1990 to 2019, with the special interest in digging their potential co-occurrence. A striking relevance between these two processes (p < .05) was shown in most cases, with the accelerated methanogenesis co-occurring with the accelerated reductive removal of COPs. The possible reason underpinning this finding was then extensively discussed. In all, by big data mining associated with discussion regarding the likely involved chemical-microbial mediate mechanisms, this study gives an update evidence showing the synergistic coupling of COP reductive removal and methanogenesis. This provides insights into a novel consideration for site dependent regulation of COP dissipation in conjunction with methanogenesis, either for efficient wastewater treatment with energy saving, or for side-effect overcoming bioremediation of polluted paddy soil.