Development of a microbial fuel cell (MFC) and analysis of microbial community dynamics

• Main Author: Beecroft, Nelli
• Published: University of Surrey 2010
• Subjects: 660.63
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520549

The basis of this work was to understand how the performance of Microbial Fuel Cells (MFCs) can be understood and improved by analysing the behaviour of the microbial communities in the anodic chamber. It was hypothesized that specific types of species generally become more abundant in MFCs over time leading to enhanced power production. An acclimatised microbial consortium obtained from a tubular MFC was used as the inoculum for the MFC described in this study: It was found to lead to a different bacterial composition, but similar power density, to those observed in an MFC inoculated with the unacclimatised community (anaerobic sludge). Using anaerobic sludge as inoculum in four replicate MFCs, both the anodic biofilm and the suspended communities evolved differently. The spatial and temporal dynamics of microbial communities were studied in the tubular MFCs. Although the removal of organic compounds was spatially different, the dynamics of the dominant bacteria showed spatial similarity, probably attributed to the versatile metabolic capabilities of species. No specific species were found the relative abundance of which would have clearly enhanced and correlated with the power production. Using similar substrate feeds and inocula, the communities consisted of metabolically different species in the two reactor types studied. Functional redundancy was observed in the anodic communities of both reactor designs. These findings suggest that the exoelectrogenic ability could be present among a range of bacteria wider than generally thought. 2 The results of this study suggest that the development of the microbial communities in MFCs with a given inoculum and substrate are determined by the reactor design and the operational conditions. Secondly, the adaptation of bacterial communities to produce electricity may not require specific changes in community composition but instead be based on the ability of bacteria to adapt generating electricity and enhance their exoelectrogenic capacity over time.