Enhanced Bioenergy Production Using Wastewater in Hybrid - Microbial Electrolysis Cell (MEC) /

Abstract

Conventional fossil fuel resources have been using these days for meeting world’s growing energy demands. The use of coal, oil, and natural gas results in greenhouse gases emissions as well as environmental pollution. Clean energy resources are of much interest these days to meet energy demands and reduce environmental pollutions. The Microbial Electrolysis Cell (MEC) is a novel technology for wastewater treatment to produce bioenergy. Typically, an assimilated biofilm is required by the MEC bio-anode to break down the organic content, but biofilm assimilation is a time-consuming process. This study used an unassimilated nickel-foam anode in a single-chamber MEC and reported successful bioenergy production at the end of the first cycle. Synthetic Dairy Manure Wastewater (SDMW) was used as a substrate as well as an inoculum in this solar-powered tubular MEC. The effects of the exposed surface area of the bio-anode on bioenergy production were also evaluated, using rate limited bio-anode - MEC and fully exposed bio-anode - MEC separation techniques. The former technique achieves a maximum methane production rate of 30.35 ± 0.03 ml/l, 14.2% more than that achieved by the later mentioned technique (26.4 ± 0.05 ml/l). Hydrogen production was approximately 800 ± 5 mm3 in both experimentations. The maximum generated current in the rate limited bio-anode – MEC was 35.5 mA. Scanning Electron Microscope (SEM) images confirmed the formation of rod-shaped along with round-shaped microbial communities on the anode surface and, interestingly, round-shaped bacteria were also grown on the cathode surface. The production of bioenergy via an unassimilated bio-anode after 13 days of operation, in conjunction with the formation of a microbial community, was a significant success in this area and has opened up many research opportunities for producing instant bioenergy from organic waste.