Methanogenesis inhibitors used in bio-electrochemical systems: A review revealing reality to decide future direction and applications.

Microbial fuel cell (MFC) is a robust technology capable of treating real wastewaters by utilizing mixed anaerobic microbiota as inoculum for producing electricity from oxidation of the biodegradable matters. However, these mixed microbiota comprises of both electroactive microorganisms (EAM) and substrate/electron scavenging microorganisms such as methanogens. Hence, in order to maximize bioelectricity from MFC, different physio-chemical techniques have been applied in past investigations to suppress activity of methanogens. Interestingly, recent investigations exhibit that methanogens can produce electricity in MFC and possess the cellular machinery like cytochrome c and Type IV pili to perform extracellular electron transfer (EET) in the presence of suitable electron acceptors. Hence, in this review, in-depth analysis of versatile behaviour of methanogens in both MFC and natural anaerobic conditions with different inhibition techniques is explored. This review also discusses the future research directions based on the latest scientific evidence on role of methanogens for EET in MFC.