How do microbial fuel cells work and what are their applications?

Microbial fuel cells (MFCs) generate electricity directly from organic matter oxidation by electrochemically active bacteria. Mechanism: In the anode chamber, bacteria (Geobacter, Shewanella) oxidize organic substrates and transfer electrons to the anode through direct contact, nanowires, or electron shuttles. Electrons flow through external circuit to cathode generating current. Protons migrate through proton exchange membrane to cathode where oxygen is reduced to water. Components include anode (carbon materials with high surface area), cathode (often with platinum catalyst), separator membrane, and bacterial biofilm. Applications: wastewater treatment with energy recovery, remote power generation (sediment MFCs), biosensors for BOD monitoring, and desalination (microbial desalination cells). Challenges include low power density (~1 W/m2 electrode area), scale-up, cathode costs, and long-term stability. Research focuses on improving power output and developing practical applications.