On any given day, it’s not uncommon to find students at the University of Michigan (Ann Arbor) out on campus raising awareness for one good cause or another.
Until recently, however, their efforts almost never involved porta-potties.
That changed on April 1 when researchers from the university’s College of Engineering set up a pop-up bathroom on central campus. Energetic volunteers used megaphones and potty humor to convince more than 130 passersby to make a donation to the university’s first-ever “pee-cycling” event.
You read that right. They were hosting a urine drive.
The one-day event was part of a U.S. Environmental Protection Agency-funded project to investigate how disinfected human urine might be safely recycled and used to fertilize crops, according to Krista Wigginton, assistant professor of environmental engineering responsible for the grant’s administration.
The drive was timed to coincide with a visit from leaders of the Rich Earth Institute (Brattleboro, Vt.), which is leading a larger reuse project.
Why pee?
Wigginton said the research is focusing on urine, rather than municipal wastewater, because urine contains a greater concentration of the nitrogen and phosphorus that plants need to grow.
“It’s easier to pull nutrients from urine than when they are diluted in wastewater,” she explained.
Urine also has other appeals. For example, it contains residual amounts of the pharmaceuticals people consume, toxins that can slip through the wastewater treatment process and be discharged into waterways.
“Researchers want to understand how pharmaceuticals affect plant life and test ways of removing them from urine before using it as fertilizer,” Wigginton said.
Urine also has less of an “ick” factor among potential users, compared to solid waste.
“Still, urine is not as sterile as people think,” explained Wigginton. The Rich Earth Institute is testing processes to eliminate pathogens, so it can be used safely to irrigate crops.
Samples collected at such places as the University of Michigan are being used to test a small reactor that produces clean struvite fertilizer, Wigginton said. Researchers will apply the fertilizer and analyze crops to learn whether any residual pollutants enter the plants or the surrounding groundwater.
Roadblocks to widespread application
Can we expect to become a nation of pee-recyclers?
Not yet, Wigginton acknowledges. Perhaps the biggest obstacle to broad-scale urine reuse is the design of U.S. wastewater systems.
“Our sewers aren’t designed to separate wastes,” Wigginton said. “But on a small scale, on a building scale, we can see it happening.”
Along with the Rich Earth Institute, the Hampton Roads Sanitation District (HRSD; Virginia Beach, Va.) is leading the way. HRSD has installed source-separating toilets in its own facilities and is building a reactor to produce struvite from the urine it collects.
Some septic system owners in coastal regions have found it is more cost effective to separate sources than to install a sewer system, according to Wigginton. “So it is being done,” she said. “But we’re a long way off from having the infrastructure to do it at a community-wide scale.”
In the meantime, the University of Michigan’s pee-cycling event helped raise public awareness.
“We want to get people thinking about urine and how it can be valuable resource,” Wigginton said.
The message appears to be getting through. “People were into it,” said Michigan engineering college spokesperson Nicole Moore. “They all wanted to be part of our UriNation.”
– Mary Bufe, WEF Highlights
August 26, 2015
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