Development of Microbial Fuel Cells for Electricity Production from Organic Solid Wastes

The goal of this study is to expand on-going research by the investigators (on biohydrogen production and fuel cell technologies) to develop microbial fuel cells (MFCs) to produce electricity directly from organic solid wastes (OSWs). Over the years, anaerobic digestion has emerged as the process of choice for stabilizing OSWs, producing methane as an end product, which in turn, has been used as fuel for heating or electricity generation. Using methane to produce electricity by generators is not an efficient process due to thermodynamic limitations. The energy content of OSWs can be more efficiently converted directly to electricity in MFCs where, microbial reactions convert chemical energy in the substrate into electrical energy. Compared to other biological energy conversion technologies, MFCs have several advantages. They can operate at higher overall efficiencies, even at ambient temperatures. The gaseous products of MFCs do not require any treatment before discharge. They do not require any energy input whatsoever. Because of no mechanical components, MFCs are expected to be robust and more reliable than the other technologies.

During this project we will construct a bench-scale MFC to evaluate the feasibility of producing electricity from cattle manure as a model OSW. It is hypothesized that the cultures isolated by us from heat-treated compost and waste sludge in our biohydrogen project- clostridium butyricum can be a candidate for use in mediator-less MFCs. We will use Nafion as the proton exchange membrane in our MFC; carbon paper for the anode; and, Pt-coated or Pt-Ru-coated carbon paper for the cathode. A flat-plate MFC configuration is proposed.

During the first year, we hope to reproduce literature findings using wastewaters and develop MFC expertise to be able to apply the current knowledge to produce electricity from organic solid wastes. Our first step will be to develop a functional mediator-less MFC using wastewater as the substrate. We hope to evaluate its performance in terms of power density (mW/m2) at different feed concentrations and compare our results with those in the literature that have used pure substrates and wastewaters as the feed. Based on these findings, a new MFC design will be formulated and tested for producing electricity from solid organic wastes. A mathematical model of the process will also be developed, calibrated, and validated.

This area of study is truly multidisciplinary, spanning applied microbiology, electrochemistry, materials engineering, and environmental engineering. This investigators have on-going research projects that will support and sustain the proposed effort. Their current interdisciplinary student team includes 1 post-doc (environmental engineering), 2 PhD students (one environmental engineering, one biology), and 3 MS students (2 environmental engineering, 1 chemical engineering) working on these projects. This research group has developed the necessary experimental skills, laboratory facilities, and instrumentation to undertake the proposed study.