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Water Science & Technology—WST Vol 57 No 7 pp 965–971 © IWA Publishing 2008 doi:10.2166/wst.2008.095

Mathematical model for microbial fuel cells with anodic biofilms and anaerobic digestion

C. Picioreanu, M. C. M. van Loosdrecht, K. P. Katuri, K. Scott and I. M. Head

Department of Biotechnology, Delft University of Technology, Faculty of Applied Sciences, Julianalaan 67, 2628 BC, Delft, The Netherlands c.picioreanu@tudelft.nl
University of Newcastle Upon Tyne, School of Chemical Engineering & Advanced Materials, Merz Court, Newcastle Upon Tyne, Tyne & Wear NE1 7RU, UK
University of Newcastle Upon Tyne, School of Civil Engineering and Geosciences, Devonshire Building, Newcastle Upon Tyne, Tyne & Wear NE1 7RU, UK


ABSTRACT

This study describes the integration of IWA's anaerobic digestion model (ADM1) within a computational model of microbial fuel cells (MFCs). Several populations of methanogenic and electroactive microorganisms coexist suspended in the anolyte and in the biofilm attached to the anode. A number of biological, chemical and electrochemical reactions occur in the bulk liquid, in the biofilm and at the electrode surface, involving glucose, organic acids, H2 and redox mediators. Model output includes the evolution in time of important measurable MFC parameters (current production, consumption of substrates, suspended and attached biomass growth). Two- and three-dimensional model simulations reveal the importance of current and biomass heterogeneous distribution over the planar anode surface. Voltage- and power–current characteristics can be calculated at different moments in time to evaluate the limiting regime in which the MFC operates. Finally, model simulations are compared with experimental results showing that, in a batch MFC, smaller electrical resistance of the circuit leads to selection of electroactive bacteria. Higher coulombic yields are so obtained because electrons from substrate are transferred to anode rather than following the methanogenesis pathway. In addition to higher currents, faster COD consumption rates are so achieved. The potential of this general modelling framework is in the understanding and design of more complex cases of wastewater-fed microbial fuel cells.

Keywords: anaerobic digestion; biofilm; mathematical model; mediator; microbial fuel cell


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