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|microbes. Credit: Wired|
| A schematic illustration of a microbial fuel cell using a paper electrode coated with carbon paste.|
Credit: Illustration by Michael Osadciw/University of Rochester
Until now, most electrodes used in wastewater have consisted of metal (which rapidly corrodes) or carbon felt. While the latter is the less expensive alternative, carbon felt is porous and prone to clogging.
“The paper electrode has more than twice the current density than the felt model,” says Bren.
Carbon paste is an essential ingredient due to its role in attracting electrons emitted by the bacteria. The specific bacterium used in Bren’s project was Shewanella oneidensis MR-1, which consumes toxic heavy metal ions in the wastewater and ejects electrons. Those electrons are attracted to the carbon coating on the positive electrode—the anode. From there, they flow to the platinum cathode, which needs electrons to carry out its own electrochemical reactions.
“We’ve come up with an electrode that’s simple, inexpensive, and more efficient,” says Lamberg. “As a result, it will be easy to modify it for further study and applications in the future.”