Cleaning up dirty water can create energy

03/27/13 Janelle Irwin
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Researchers at the University of South Florida showed off their work with waste water and other testing technologies to officials from the Environmental Protection Agency. During lab tours today, Professor Daniel Yeh demonstrated how the water that gets dumped, flushed or otherwise thrown out can be put to better use.

“If you can just re-route the electrodes that’s built into the waste organic matter, we can actually turn the waste organic matter into methane which is basically natural gas. So, we can basically get natural gas out of waste water as a renewable form of natural gas. There are other people working on technologies even to directly extract electricity from waste water using microbial fuel cells.”

Yeh said the revolutionary process builds on the usual waste water treatment process called activated sludge.

“There are some problems of activated sludge, even with all of the benefits it provides. One is that it uses a lot of energy in the process because we have to feed a lot of oxygen to the microorganisms to get them to do this. So, when energy is cheap nobody really thinks much of this problem, but now we’re really thinking a lot about energy constraints.”

Treating waste water without chemicals requires pumping oxygen into the water with biological organisms – like algae.

“To microbes, they see it as food. So, what we see as waste is actually food for these microorganisms. So, we basically enlist the help of microorganisms to do what they do best – to remove the waste material from the waste water.”

Yeh’s process uses algae that’s grown in the lab. But Florida’s waterways are already inundated with excess levels of algae because of nutrient pollution. Ivy Drexler, a PhD student working on the waste water to energy project said the algae could be gathered from natural resources, but it wouldn’t be efficient.

“We’re looking at the root problem is there’s too many nutrients in that fresh water resource. So, part of that problem could be runoff or it could be waste water treatment plant discharge. So, you could I guess harvest algae from nature but the problem with algae bio-fuel right now is it’s really hard to harvest and de-water and kind of make that resource available for further treatment and further processing. So, taking it out of nature, you might be adding more energy than it’s worth.”

Instead Drexler said nutrient pollution should be kept in check. After years of debate, the EPA finally set numeric nutrient standards. Environmentalists who pushed for the standards were enraged when the EPA then handed that responsibility to the state Department of Environmental Protection who was accused of pandering to polluters. However, EPA water chief Nancy Stoner is confident the Florida agency will do a good job.

“Florida made great progress. EPA did propose some standards to fill in some gaps where Florida had not yet set standards and then Florida stepped up and agreed to make more investment and to really address the problem. We’re delighted that Florida has done so.”

Supporters of letting the state take the reigns on Florida’s nutrient pollution standards argue it’s better that way because some waterways need different consideration. Stoner said Florida is working to make sure nutrient pollution does not remain a problem

“Working to address the main sources of nutrient pollution. So that’s sewage that we were talking about earlier today and recovery of nutrients as we’ve been talking about in the labs today. Also addressing storm water and runoff from road crops, from animal operations. Those kinds of sources are the sources that Florida is working to address to reduce the nutrient pollutions that causes algal blooms in Florida waterways.”

Researchers in the interdisciplinary lab at USF are seeking a patent on a machine that can look for pathogens and other organisms living in water. It takes a sample and isolates, or de-waters them. The result from many Florida waterways is a brown-tinged water. The revolutionary machine can also be used to make sure food is safe. USF micro-biology tech Sonia Magana is researching a new way to test pre-packaged lettuce for things like E. Coli.

“If we can test the water, it’s been shown that bacteria will fall into the water and stay there. So, if the water is contaminated, pretty much, the lettuce is contaminated.”

It takes less than an hour. That could be a huge improvement for lettuce packaging plants where tests take at least one full day.

“They take that and they send it off to other labs that will test for pathogens. So, they collect – I’m not sure what the frequency is – but if you can imagine there’s maybe a pallet and there’s probably, like, 20 boxes with maybe ten bags in each box. So, they have to sample from that big thing and they can only grab a certain amount. So, that’s what they currently do and then they take those samples and they enrich it which means that they take the lettuce and put it in some media that the bacteria like to grow in and then you have to let it grow over night – for, like, 24 hours. From there you have to try to isolate it.”

EPA officials said the research being done at universities like USF is important because it can lead to new technology that can make water cleaner, more sustainable and reduce costs. Research funding though could be under threat because of federal spending cuts, but the EPA is trying to find ways to encourage venture capitalists to invest in projects.


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