Design and testing of a microbial fuel cell for the conversion of lignocellulosic biomass into electricity
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Previous research has demonstrated that microbial fuel cells (MFCs) have the ability to degrade soluble substrates such as wastewater; however, very few studies have attempted the conversion particulate biomass to electricity in an MFC. A single-chamber, air cathode MFC was developed using a solid, lignocellulosic substrate (corncob pellets) as the electron donor. The first trial, using a prototype reactor with a graphite rod anode, ran for 415 hours, and generated a maximum open circuit voltage and current of 0.67 V and 0.25 mA, respectively. The second trial employed graphite brush anodes and multiple microbial inocula. A pasteurized soil inoculum resulted in negligible power (P = 0.144 mW/m3). The addition of rumen fluid, which naturally contains cellulose-degrading microorganisms, and Geobacter metallireducens, resulted in Pmax values of 77 mW/m3 and 159 mW/m3, respectively. Analysis of hydrogen, methane, organic acids, and the mass of substrate consumed provided insight into the relationship between cellulose oxidation, methanogenesis, and power production.