Use of Landfill Leachate to Generate Electricity in Microbial Fuel Cells

Abstract

Microbial fuel cells, in which microorganisms catalyze the transfer of electrons released from theoxidation of organic compounds onto an electrode, are a promising biotechnological approach for harvesting energyin the form of electricity from certain wastes. The purpose of this study was to determine if landfill leachate is aproductive source of substrate and microbes for generating electricity in microbial fuel cells. Research methodsincluded filling the anodic chambers of multiple fuel cells with landfill leachate. The cathodic chambers were filledwith a buffer solution of KH2PO4 and were separated from the anodic chambers by a proton exchange membrane(NafionTM). Graphite plates were used as the electrodes in both chambers. Findings from this study show thatmicroorganisms in landfill leachate are electrochemically active, and thus, landfill leachate can be an effective sourceof bio-electricity. Further results indicate that these electricity-producing microbes reside on the graphite anode, asopposed to being suspended throughout the leachate fluid. Experiments indicated that the leachate may lack enoughcarbon constituents (or food sources) to support long-term electrical generation. The addition of 10 mL of a 0.4%soluble sugar mixture (0.1% each of glucose, cellobiose, maltose, and xylose) provided enough food source for themicroorganisms in the leachate to generate electrical voltage that was nearly three times the amount producedwithout the sugar mixture (0.120 volts). Furthermore, this maximum voltage generation (0.450 volts) continued fornearly two weeks, over twice the length of generation for the leachate without sugar. Additionally, leachate ChemicalOxygen Demand (COD) levels were reduced in initial tests after fuel cell electrical generation was complete,indicating that microbial fuel cells are potentially effective in treating landfill leachate. A cost analysis of a conceptuallarge scale design indicated that MFC technology is not mature enough to justify the implementation of this designbased on economics alone. However, as energy costs continue to rise and MFC power production is maximized,MFC implementation could become more feasible.