MFC (image) Arizona State University Caption An MFC consists of an anode, a cathode, a proton or cation exchange membrane and an electrical circuit. In the left compartment, anode-respiring bacteria (like Geobacter) attach themselves to the anode, forming a sticky residue or biofilm. In the course of their metabolic activity, these bacteria strip electrons from organic waste. The electrons then flow through a circuit to the cathode, producing electricity in the process, in addition to CO2 and water. Hydroxide or OH- ions are transported from the cathode into the surrounding electrolyte. Note: in an experimental set-up lacking organic waste, an electron donor -- typically acetate -- is supplied in the growth medium, as a nutrient source for the anode respiring bacteria. Credit The Biodesign Institute At Arizona State University Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.