Optimizing the Microbial Fuel Cell-Microbial Electrolysis Cell Coupled System for Sustainable Hydrogen Gas Production, Electricity Generation, and Improved Wastewater Treatment
The microbial fuel cell-microbial electrolysis cell (MFC-MEC) coupled system may pose an inexpensive and effective solution to current environmental problems as it combines two bioelectrochemical devices, the MFC and the MEC, to simultaneously treat wastewater and produce hydrogen gas using anaerobic bacteria. A major limitation of current research is that all of the voltage generated by the MFC is applied to the MEC, producing only hydrogen gas, when in fact the applied voltage can be varied, allowing for electricity to be extracted from the system as well. Using semiconductor switches and capacitors, a novel power management device capable of varying the applied voltage was developed, enabling the production of electricity and hydrogen gas in various proportions. A low-cost electrophoretic deposition method was also used to coat graphite plate anodes with multi-walled carbon nanotubes in order to increase surface area to volume ratios and improve electron transfer. The power density and hydrogen gas outputs were increased by approximately 150% and 50% respectively. The MFC-MEC system developed in this research can produce hydrogen gas, electricity, or both simultaneously based on commercial demand. The MFC-MEC system has wide applications, ranging from use in wastewater treatment plants to the transportation industry.