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 (<i>p</i> &lt; .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.

还原脱氯（Reductive dechlorination）是厌氧环境中耗竭氯代有机污染物（chlorinated organic pollutants, COPs）的最高效途径，而该环境中通常会大量发生甲烷生成作用（methanogenesis）。二者本质上均为微生物介导的电子受体过程（microbial-mediated electron accepting processes），近数十年来备受关注：前者对于氯代有机污染物污染的环境修复具有重要意义，后者则与全球变暖效应及沼气特性息息相关。本研究基于1990年至2019年发表的68篇文献中的337组测量数据，对这两种还原过程进行了全面综述，并重点探究二者潜在的共现关联。多数情况下，两种过程间呈现出显著相关性（p<0.05）：加速的甲烷生成作用与加速的氯代有机污染物还原去除呈共现状态。随后，本研究对支撑该发现的潜在机制进行了广泛探讨。总而言之，本研究通过大数据挖掘，并结合对所涉及的化学-微生物介导机制（chemical-microbial mediate mechanisms）的探讨，提供了更新的证据，表明氯代有机污染物还原去除与甲烷生成作用存在协同耦合关系。该研究为结合甲烷生成作用进行场地特异性调控以消减氯代有机污染物提供了全新的思路——既可用于实现节能高效的废水处理，也可为克服污染稻田土壤生物修复（bioremediation）的副作用提供参考。