Optimization of culture conditions and electricity generation using Geobacter sulfurreducens in a dual-chambered microbial fuel-cell

The promise of generating electricity from the oxidation of organic substances using metal-reducing bacteria is drawing attention as an alternate form of bio-technology with positive environmental implications. In this study, we examined various experimental factors to obtain the maximum power output in a dual-chamber mediator-less microbial fuel-cell (MFC) using Geobacter sulfurreducens and acetate as an electron donor in a semi-continuous mode. The G. sulfurreducens culture conditions were optimized in a nutrient buffer containing 20 mM of acetate and 50 mM of fumarate at pH 6.8 and 30 °C. For use in the MFC system, electrodes were made with carbon paper (area: 11.5 cm2) and spaced 1.5 cm apart. Once the MFC was inoculated with the pre-cultured G. sulfurreducens in the anode chamber and while air was continuously sparged to the cathode chamber, the cells produced electricity stably over 60 days with the regular addition of 20 mM acetate, generating the maximum power density of 7 mW/m2 with a 5000 Ω load. The current output was significantly increased, by 1.6 times after 20 days of incubation under the same experimental conditions, when the carbon-paper anode was coated with carbon nanotubes.