During the academic year, on Thursday, Friday, and Saturday nights between 10 p.m. and 2 a.m., the wastewater treatment plant that serves the University of New Hampshire experiences a surge in the amount of urine flowing into the facility. It’s not hard to figure out why, but for the plant, it’s no joke. The increase in urine flow is so dramatic that monitoring data from those time periods show peaks in the concentration of nitrogen entering the plant. Wastewater treatment plants have a maximum nitrogen concentration they are permitted to discharge, and the higher the incoming nitrogen concentration, the more resource-intensive and costly the treatment is. David Cedarholm, a UNH alumnus who works for the Durham Department of Public Works, brought the nitrogen spikes to the attention of Nancy Kinner, a professor of environmental engineering at UNH—and Kinner saw the potential for a learning experience.
During the spring semester of 2013, Kinner explained the problem to her engineering design class and said she hoped some of the students would design, build, and test a mobile urine collection unit on campus. Four seniors—three environmental engineering majors and a business major—turned the vision into a reality. They built a collection unit comprised of three bucket-shaped urinals enclosed in a shed and attached to a 264-gallon tank, all on a utility trailer. With permission from the UNH Police, the group parked the unit, which they called the Pee Bus, near downtown Durham—the center of campus nightlife—for four weekends. They flagged down students leaving bars to invite them to make a “donation.” Alyson Packhem, one of the project members, said the response was remarkably positive. “People were excited to try it out,” said Packhem, seen above outside the Pee Bus.
The Pee Bus team could have stopped there and simply delivered the urine to the wastewater treatment plant during a time of low flow. But instead they arranged for the urine to be pasteurized so it can be used as fertilizer, a practice being researched and field-tested in both developed and developing nations across the globe. (In the Northeast, the Rich Earth Institute of Brattleboro, Vermont, has been conducting a urine-fertilizer experiment since 2012.) Dorn Cox of Tuckaway Farm in Lee, N.H., is one of two farmers who agreed to receive the urine-fertilizer generated by the Pee Bus. Urine diversion for fertilizer is “an elegant solution,” Cox said, because it requires minimal treatment, the nitrogen is in a form that’s readily available to plants and bacteria, the fertilizer is easy to apply with a sprayer, and it takes advantage of a resource otherwise treated as waste. Cox said he hopes to see the practice adopted around the region. “We need to shift,” he said, “from talking about waste management to talking about nutrient management.” The 250 gallons of urine-fertilizer from the Pee-Bus will be pasteurized in time for the 2015 growing season.
So, will buildings on the UNH campus be re-plumbed to divert urine? That may be too much to expect, but the UNH alum whose comments got everything started said he’s on the lookout for another group of students to keep the Pee Bus going. The Durham wastewater plant’s treatment costs could be notably lower if 10,000 gallons of urine a year were diverted. “That seems like a big number,” David Cedarholm said, “until you consider that UNH and Durham produce 8,000 gallons of urine a day.”