Engineers at Oregon State University have made a significant advance toward producing electricity from sewage, by the use of new coatings on the anodes of microbial electrochemical cells that increased the electricity production about 20 times.
In microbial electrochemical cells bacteria from biowaste such as sewage are placed in an anode chamber, where they form a biofilm, consume nutrients and grow, in the process releasing electrons, thus generating electricity.
By coating graphite anodes with a nanoparticle layer of gold, the production of electricity increased 20 times. Coatings with palladium produced an increase, but not nearly as much. And the researchers believe nanoparticle coatings of iron - which would be a lot cheaper than gold - could produce electricity increases similar to that of gold, for at least some types of bacteria.
A similar approach may be able to produce hydrogen gas instead of electricity, with the potential to be used in hydrogen fuel cells that may power the automobiles of the future. In either case, the treatment of wastewater could be changed from an energy-consuming technology into one that produces usable energy besides significantly reducing the cost of wastewater treatment.Advances in nanofabrication help develop efficient electrode materials due to the remarkable structural, electrical and chemical properties of nanomaterials.
It might also find applications in rural areas or developing nations, where the lack of an adequate power supply makes wastewater treatment impractical. It may be possible to create sewage treatment plants that are completely self-sufficient in terms of energy usage.