Researchers in Bath, UK have developed a fuel cell powered by microbes in the soil that can be used to generate clean drinking water.
The team of chemical and electrical engineers at the University of Bath has demonstrated a cheap, simple soil microbial fuel cell (SMFC) that can be buried in the earth to power a water purifier. The proof-of-concept design was demonstrated during field testing in North-East Brazil and showed that SMFCs can purify about three litres of water per day, enough to cover a person’s daily water needs.
The project is a collaboration with a team of geographers from Universidade Federal do Ceará and a team of chemists from Universidade Federal do Rio Grande do Norte.
Testing took place in Icapuí, a fishing village located in a remote semi-arid location where the main source of drinking water is rainwater and access to a reliable power network is scarce.
The system, developed by staff from Bath’s Department of Chemical Engineering and Department of Electronic & Electrical Engineering, consists of two carbon-based electrodes 4cm apart and connected to an external circuit. The anode is buried inside the soil while the cathode is exposed to air on the soil surface.
Microbes populate the surface of the anode and consume organic compounds present in soil, generate electrons. These electrons are transferred to the anode and travel to the cathode via the external circuit, generating enough current to charge a 600 mAh battery in 8.5 hours. This was within within 12 percent of the current produced in the lab and can be used to treat 1.4 litres of water.
A single SMFC unit costs just a few pounds, which could be further reduced with mass production and with the use of local resources for the electrode fabrication.
The need for sustainable water purification in the area stems from the fact that the main supply of water is from precipitation, which needs to be chlorinated to be drinkable. A stack of several