Heavy metal removal and recovery from contaminated sediments based on bioelectrochemical systems: Insights, progress, and perspectives

Heavy metals accumulate in sediments, and there is a need to develop environmentally friendly methods for treating these pollutants. Sediment microbial fuel cells (SMFCs) generate electrons and electric fields through the degradation of organic pollutants by anodic microorganisms. The electric field causes positively charged heavy metals to migrate to the negatively charged cathode surface and receive electrons to reduce to a less toxic form, thus enabling sediment remediation without external power input. This study introduces the research progress of SMFCs for heavy metal remediation from the following aspects: (i) by summarizing the reaction principles of SMFCs; (ii) clarifying the factors affecting heavy metal remediation; (iii) comparing the performances of two SMFC configurations: vertical configuration: the anode and cathode are, respectively, placed in the sediment and overlying water; horizontal configuration: they are both placed in the sediment layer; (iv) illustrating the state-of-the-art research progress of SMFCs for heavy metal remediation. In contrast to other heavy metal removal technologies by electrochemical treatments, SMFCs provide a bioelectrochemical means to achieve zero-carbon emission treatment by integrating with other promising technologies. Therefore, this study addresses SMFC challenges and bridges research and development gaps.