POWER FROM H₂0
Using Wastewater Bacteria to Power Fuel Cells

Envision an economical and simple wastewater treatment system that provides both clean water and generates electricity for people in countries with limited access to both.

Such a system is possible thanks to revolutionary research by OSU biological and ecological engineering professor Hong Liu and her colleagues. Liu’s team specializes in microbial fuel cells (MFCs), devices that convert biodegradable materials, such as pollutants in wastewater, into electricity using bacteria. As the bacteria consume the pollutants, they shed excess electrons, which flow through a circuit and generate electricity. In the process, pollutants are broken down, resulting in clean water.

“Bacteria use only part of the energy they produce, releasing the rest into the environment,” says Liu, who collaborates with fellow OSU professor Yanzhen Fan, graduate student Hongqiang Hu, and visiting scholars. “We are able to capture the energy that is released.” Air cathode MFCs are self-sustained, efficient, and require minimal maintenance, Liu says. “So everything recycles!”

Historically, power outputs from MFCs have been so low the devices have not been perceived as viable sources of electricity. However, Liu’s research in fuel cell design is changing that perception.

“We have successfully modified the fuel cell structure to enhance power generation,” she says. Recently, her team designed an MFC that is capable of generating approximately one order of magnitude, or about 10 times, more electricity than previously generated from an air cathode microbial fuel cell of the same size. The researchers generated 1010 watts per cubic meter of reactor, or enough to power sixteen 60-watt light bulbs.

These design improvements could lead to distributed energy production in developing nations and reduce the cost of operating wastewater treatment plants in the U.S. and elsewhere.

Five percent of the electricity in the U.S. is used for water and wastewater treatment, mainly to power pumps and other equipment. “By incorporating microbial fuel cells in water treatment facilities, the cost of operation could be reduced,” Liu says.

Although scaling up MFCs to help power large wastewater facilities is a long-term goal of Liu’s, she says small-scale systems will be feasible sooner. “It would be useful to build a smaller system for individual households. This is something the world can use very soon, especially in China and India.”

Although MFCs can’t solve all global environmental and energy problems, they can help, Liu says. “Our research results are very promising. There is a real future here, and I hope we can make a small contribution to the world.”

Liu, who joined OSU two years ago and is part of the Biological and Environmental Systems Research Cluster, is involved in other research with her team. They have developed a new bioelectrochemically assisted microbial reactor that produces hydrogen from wastewater, and are also working on biodiesel production using a species of algae that contains up to 70 percent oil.

It is innovation like this that will lead to prosperity in Oregon, and worldwide.