Hong Liu, an engineer at Oregon State University, has developed greatly improved new methods to produce electricity from the processing of wastewater. Photo: Oregon State University
Oregon State University (OSU) have made a breakthrough in the performance of
microbial fuel cells that can produce electricity directly from wastewater,
opening the door to a future in which waste treatment plants not only will
power themselves, but will sell excess electricity.
technology developed at OSU can now produce 10 to 50 more times the
electricity, per volume, than most other approaches using microbial fuel cells,
and 100 times more electricity than some.
this could eventually change the way that wastewater is treated all over the
world, replacing the widely used “activated sludge” process that has been in
use for almost a century. The new approach would produce significant amounts of
electricity while effectively cleaning the wastewater.
The findings are
published in Energy and Environmental
technology works on a commercial scale the way we believe it will, the treatment
of wastewater could be a huge energy producer, not a huge energy cost,” said Hong Liu, an associate professor in the OSU Department of
Biological and Ecological Engineering. “This could have an impact around the
world, save a great deal of money, provide better water treatment, and promote
Experts estimate that
about 3% of the electrical energy consumed in the United States and other
developed countries is used to treat wastewater, and a majority of that
electricity is produced by fossil fuels that contribute to global warming.
biodegradable characteristics of wastewater, if tapped to their full potential,
could theoretically provide many times the energy that is now being used to
process them, with no additional greenhouse emissions.
reported several years ago on the promise of this technology, but at that time
the systems in use produced far less electrical power. With new concepts—reduced
anode-cathode spacing, evolved microbes, and new separator materials—the
technology can now produce more than two kilowatts per cubic meter of liquid
reactor volume. This amount of power density far exceeds anything else done
with microbial fuel cells.
The system also
works better than an alternative approach to creating electricity from
wastewater, based on anaerobic digestion that produces methane. It treats the
wastewater more effectively, and doesn’t have any of the environmental drawbacks
of that technology, such as production of unwanted hydrogen sulfide or possible
release of methane, a potent greenhouse gas.
The OSU system
has now been proven at a substantial scale in the laboratory, Liu said, and the next step would be a pilot
study. Funding is now being sought for such a test. A good candidate, she said,
might initially be a food processing plant, which is a contained system that
produces a steady supply of certain types of wastewater that would provide
significant amounts of electricity.
research should also find even more optimal use of necessary microbes, reduced
material costs and improved function of the technology at commercial scales,
OSU scientists said.
Once advances are
made to reduce high initial costs, researchers estimate that the capital
construction costs of this new technology should be comparable to that of the
activated sludge systems now in widespread use today—and even less expensive
when future sales of excess electricity are factored in.
cleans sewage by a very different approach than the aerobic bacteria used in
the past. Bacteria oxidize the organic matter and, in the process, produce
electrons that run from the anode to the cathode within the fuel cell, creating
an electrical current. Almost any type of organic waste material can be used to
produce electricity—not only wastewater, but also grass straw, animal waste,
and byproducts from such operations as the wine, beer, or dairy industries.
The approach may
also have special value in developing nations, where access to electricity is
limited and sewage treatment at remote sites is difficult or impossible as a
The ability of
microbes to produce electricity has been known for decades, but only recently
have technological advances made their production of electricity high enough to
be of commercial use.
Source: Oregon State University