Abstract
Microbial fuel cells (MFCs) are expected to become direct energy conversion devices driven with organic matter in wastewater from industrial plants, food factories and agricultural processes. Recently, many researchers in Europe and the United States have been trying to develop the novel electricity generation systems based on MFCs. In most of previous work, the major target is to find out more effective pairs of microbes and electron mediators. From the veiwpoint of safety for handling, baker's yeast, i.e. Saccharomyces cerevisiae, is selected to use in the present electricity generation experiments. The prototype of a MFC consists of two compartments, i.e. the anode side and the cathode side containers, divided by a proton exchange membrane (Nafion 112). The baker's yeasts with O.1M phosphate buffer solution (pH 7.0), glucose as substrate and a drop of methylene blue dilute solution as electron mediator were put in the anode side container. In the cathode side, 0.2M potassium ferricyanide was stocked with O.1M phosphate buffer solution (pH 7.0). Carbon paper, of which area was 9cm^2, was employed for the electrodes, and a variable resistor was used as an electrical load of the MFC. Throughout the experiments, the open circuit voltage (OCV), the current-voltage (I-V) and the current-power (I-P) characteristics were obtained in some cases with different operating conditions. The OCV of the present MFC prototype was found in the range between 0.5V and 0.6V. In addition, it is clarified that the power output increases together with solution temperature in the range between 11.4℃ and 33.5℃ and the power density at 33.5℃ reaches 35μW/cm^2. The initial yeast content and the initial concentration of glucose also affect the electricity generation performance.
