Bridging between electrochemistry and microbiology for a brighter future: Microbial fuel cells

Abstract

In a world of global warming and limited renewable resources, microbial fuel cells (MFCs) gain momentum in relevance and efficiency. Utilizing just organic waste and electrogenic mud microbes found in most parts of the world, these battery-like mechanisms can recycle waste to produce consumable electricity. After inserting mud and a food substrate, the microbes in the MFCs feed on the substrate and release electrons. These electrons flow through the MFC wiring from an anode to a cathode, can be used for external use, and ultimately react with oxygen to form purifiable water. MFCs from a supplier were used to test the effects of amount and different types of food substrates such as white sugar and compost on maximum electrical output. Results yielded that different cultures of mud and bacteria need certain optimal amounts and proportions of nutrients in order to yield the highest output. High amounts of sugar substrate kills the microbes due to dehydration, and the microbes need a 1:2:1 ratio of nitrogen, carbon, and phosphorous compounds (tested with soil indicators). Using the substrate that provides the highest output at a certain amount in multiple MFCs, a high electron flow was generated after connecting the MFCs in a series circuit. An external USB boost converter hardware mechanism was attached to the circuit, and channeled the electricity made into charging smartphones. In the future, the USB boost converter hardware must be able to charge a smartphone faster to improve its efficiency. Through this research, the combination of electrochemistry, mechanical engineering, and microbiology work in tandem to provide consistent accessible sources of energy in African villages.