Major advance made in generating electricity from wastewater

Aug 13, 2012
Research at Oregon State University by engineer Hong Liu has discovered improved ways to produce electricity from sewage using microbial fuel cells. (Photo courtesy of Oregon State University)

Engineers at Oregon State University 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.

The new 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.

Researchers say 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 have just been published in Energy and , a professional journal, in work funded by the National Science Foundation.

"If this 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 ," said Hong Liu, an associate professor in the OSU Department of Biological and . "This could have an impact around the world, save a great deal of money, provide better water treatment and promote energy sustainability."

Experts estimate that about 3 percent of the consumed in the United States and other developed countries is used to treat wastewater, and a majority of that electricity is produced by that contribute to global warming.

But the 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 .

OSU researchers 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 .

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.

Continued 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.

This technology 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 , 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 result.

The ability of microbes to produce electricity has been known for decades, but only recently have technological advances made their production of high enough to be of commercial use.

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5 / 5 (4) Aug 13, 2012
Well, well, well...that is a somewhat unexpected source of cheap electricity (that electricity can be made from sludge isn't new, but that it really seems worth the while in wastewater is).

I'm all for adopting this technology ASAP. Wastewater is, after all, a pretty constant source and not one that is subject to the swings of some other alternative means of energy production.

Some processing plants as well as municipal wastewater processing should be all over this for wastewater treatment.
5 / 5 (1) Aug 13, 2012
What is interesting is that after the sludge is used for electricity generation from the microbes the sludge will be even more effective as a soil fertilizer.
2.3 / 5 (3) Aug 13, 2012
this article does everything it can to talk about the technology without explaining it.
not rated yet Aug 13, 2012
this article does everything it can to talk about the technology without explaining it.

Its probably not pending for patent yet and they dont want to give out secrets before starting a business. thats what i would do anyway.
2.2 / 5 (5) Aug 13, 2012
If the electricity is cheaper, then go for it.
1 / 5 (2) Aug 14, 2012
What about radioactive waste?
5 / 5 (1) Aug 14, 2012
What about radioactive waste?

What about it? Radioactivity is a physics effect - not a chemistry effect. Bacteria can't affect the half life of radioactive material.

What bacteria can do is e.g. show an ability to concentrate certain atom types (much like your liver tends to concentrate toxic stuff like mercury). This doesn't render the radioactive material any less radioactive, but it may allow it to be more easily extracted afterwards.

There are bacteria that do live off of radioactivity created by radioactive material
But that doesn't mean they 'eat' radioactivity - rather they use this source of radiation and not the source of radioactivity most other plants use (the sun).
5 / 5 (1) Aug 14, 2012
The entrepreneur in me wakes up - so you have a large block of apartments (flats) - and each time someone uses the bathroom - they get a 5 cent credit towards their rent. The apartment complex has a small power plant - that in conjunction with solar panels on the roof - generates enough power run the complex. They save money because they don't have to pay a sewer fee to the local city, and they sell bags of compost to a local nursery store - sounds like win/win/win.
5 / 5 (1) Aug 14, 2012
that in conjunction with solar panels on the roof - generates enough power run the complex.

Not sure the wastewater of one appartment would render THAT much electricity. 5 cents per use is most certainly a pretty bad deal for you.
(and also pretty sure that the roof area of a block of flats won't generate enough electricity with PV to make a big dent in your electricity bill - much less power the complex in a stand-alone fashion. Unless you already have built zero-energy-appartments )

..and you'll have to pay the sewer fee anyhow since the stuff doesn't go away. Occasionally you'll have to flush the remainder - including the bacteria that lived and died.

For such local use these microreactors are probably not worth the investment (yet)
not rated yet Aug 14, 2012

There are bacteria that do live off of radioactivity created by radioactive material

i wonder if ATP fails it can cause radioactive particles?
5 / 5 (1) Aug 14, 2012
Someone downvoted my question because I was ignorant about the nature of radioactivity! However will I learn about the actual nature of radioactivity now?
5 / 5 (1) Aug 14, 2012
and also pretty sure that the roof area of a block of flats won't generate enough electricity with PV to make a big dent in your electricity bill - much less power the complex in a stand-alone fashion.

That would depend on the density of the apartments. Here in the U.S. many apartments are pretty spread out - and just 2 or 3 levels - so solar panels would have enough area. In a larger block - you are probably right - and often the roofs are used for other purposes such as sitting areas - or satellite dishes. But it would help - and probably in the future we will be increasing the efficiency of all or our buildings - so they can be run on a much smaller set of panels. We have some zero energy homes here now - that use a very small set of panels - I think just 2KW - but are super insulated - and use super high efficiency appliances.

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