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Bioelectricty Generation from Domestic Waste

The Microbial Fuel Cell Pit Latrine

UMass Research Team: Caitlyn Butler, Jacob Weinrich, Cynthia Castro

The objective of this project is to design and field-test a new “green latrine” that uses microbial fuel cell technology to purify human waste, producing compost for farming and generating electricity. The proposed latrine works like a battery. It has an anode and a cathode and is similar to a fuel cell where a fuel, for lab1example hydrogen, is oxidized at the anode, and an oxidant, such as oxygen, is reduced at the cathode. In this case, the organic waste matter is the fuel and nitrate is the oxidant. After solid wastes are first filtered in a composting chamber, dissolved waste organic matter is oxidized in an anode chamber. The oxidation of organic matter is assisted by bacteria on the anode surface and uses the anode as an electron acceptor to complete their metabolic reaction. Electrons released in this biological process are conveyed through a load-bearing circuit, producing electricity, to the cathode compartment. There a different community of bacteria uses the cathode as an electron donor, capturing the energy from the electrons, to reduce harmful nitrates in the waste stream. The primary nitrogen compound found in human waste is ammonium, which can be broken down by oxidation, or nitrification. In Butler’s latrine, nitrification takes place thanks to bacteria living in an intermediate chamber that separates the anode and cathode chambers. The result is effluent water that is quite low in organic matter and nutrients, minimizing pathogen persistence in the environment.map

Dr. Butler traveled to Ghana in May to install a pilot version of her device. Working with graduate students Cynthia Castro and Joe Goodwill, collaborators Mark Henderson and Brad Rogers from Arizona State University, and residents of the small village of Agona Nyakrom, they installed the first working model of her Microbial Fuel Cell Latrine.

Learn more at Dr. Butler's website: http://people.umass.edu/csbutler/

This project is funded by the the Grand Challenges Exploration program supported by the Bill & Melinda Gates Foundation.

Background Information on MFCs:

Related UMass Research Projects:

            • Electrofuels via Direct Electron Transfer from Electrodes to Microbes, (Derek Lovley, Caitlyn Butler, Kelly Nevin, Tim Russell) Advance Research Project Agency - Energy (ARPAE)