An environmental engineer at the University has created a device similar to a hydrogen fuel cell that uses bacteria to treat wastewater and create electricity.
Lars Angenent, Ph.D., assistant professor of chemical engineering and a member of the University’s Environmental Engineering Science Program, has devised an upflow microbial fuel cell.
The device is fed continually and, unlike most microbial fuel cells, works with chambers atop each other rather than beside each other.
Angenent has created electricity with the device — in its current mode, about the size of a thermos bottle — and said it has to be scaled up considerably to someday handle the 2 million or so gallons of wastewater it needs to treat to churn out enough power.
“We have proven we can generate electricity on a small scale,” Angenent said. “It will take time, but we believe the process has potential to be used for local electricity generation.
“The upflow microbial fuel cell is a promising wastewater treatment process and has, as a lab-scale unit, generated electricity and purified artificial wastewater simultaneously for more than five months.”
A description of the process and research was published in the July issue of Environmental Science and Technology.
Angenent’s co-authors are Jason He, his doctoral student, and Shelley D. Minter, Ph.D., of the Saint Louis University Chemistry Department.
Angenent has filed a provisional U.S. patent on the process. He has received a $40,000 Bear Cub Fund award from Washington University to develop the concept. The Bear Cub Fund was initiated by Theodore J. Cicero, Ph.D., vice chancellor for research, to support faculty in applied studies not normally supported by federal grants from the National Institutes of Health, the National Science Foundation and other sources.
The purpose of the awards is to support research or development that is designed to extend basic observations to make them more attractive for licensing by commercial entities or to serve as the “foundation” for a startup company.
Angenent uses a carbon-based foam with a large pore size on which biofilm grows, allowing him to connect two electrodes in the anode and cathode chambers with a conductive wire. In a hydrogen fuel cell, a membrane separates the anode and cathode chambers.
When hydrogen meets the anode electrode, it splits into protons and electrons, with protons going across the membrane to the cathode chamber, and electrons passing over the wire between electrodes to create a current.
Oxygen is added to the cathode chamber, and on the electrode there is a reaction of electron plus proton plus oxygen to form water. Catalysts, such as platinum, are needed on both electrodes to promote the reactions.
“We are doing basically the same thing as is done in a hydrogen fuel cell with our microbial fuel cell,” Angenent said.
“We’ve found that the bacteria on the anode electrode can act as the catalyst instead of platinum.”
“The bacteria form a biofilm on the anode electrodes, and what I want to do is optimize this process so that we get higher currents, which should allow us to scale up the system.”
Angenent said that producing energy from wastewater should be a high international priority because of population growth and worldwide depletion of energy resources.
Anaerobic wastewater treatment can also produce methane or hydrogen gas as fuels.
The advantage of biological electricity generation over methane and hydrogen production is the higher yield of readily useful energy.
He noted that a bioelectricity generating wastewater treatment system in just one large food-processing plant could power as many as 900 American single-family households.