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Issues Of The Environment: 'Pee-Cycling' To Create A Sustainable Source Of Fertilizer

Nov 14, 2018

Dr. Nancy Love, professor of civil and environmental engineering at the University of Michigan
Credit University of Michigan / umich.edu

Searching for new sources of natural fertilizer is an ongoing process, and a University of Michigan research project is exploring use of an unending source.  In this week's "Issues of the Environment," WEMU's David Fair talks with U-M professor of civil and environmental engineering Dr. Nancy Love about the Urine Diversion Research Project. 


Overview

  • Urine contains nitrogen, phosphorus, and potassium—nutrients that are essential for plants to grow.  Nitrogen promotes leaf growth.  Phosphorus grows roots, flowers, and seeds. Potassium encourages strong stems, flowers and fruits, and it helps move water within a plant.  According to the International Plant Nutrition Institute, commercial fertilizers are used to augment 40-60% of world food production. 

  • Professor Nancy Love, principal investigator for UM's Urine Diversion research project, and her team have installed special toilets and urinals at a University of Michigan engineering building to divert urine, concentrate it, sanitize it, and prepare it for re-use as fertilizer.

  • Funded by a $3 million dollar grant from the National Science Foundation, the project team is assessing if diverting urine will be a less energy intensive and more cost-effective way to reduce the nutrient loads in wastewater effluents and create fertilizer for agriculture.

  • The hope is that on a large scale this sort of recycling might offset the need for commercial fertilizers, which are synthesized using fossil fuels, mined using strong acids that pollute the environment, and also deplete natural mineral resources.  Researchers also hope “pee-cycled” fertilizer will be less energy intensive and more cost-effective way to reduce the nutrient loads in wastewater effluents.  Removing the high concentrations of nutrients from urine is expensive and energy-intensive, and although many water treatment plants do what they can to lessen the nutrient load before releasing the “effluent” back into the environment, some do not.  Excess nutrients (partially from attributed to wastewater effluents, but also to commercial fertilizer runoff) causes eutrophication of natural water bodies, leading to harmful algal overgrowths that kill fish and other aquatic life and poison waterways.

  • The main roadblock to widespread application of urine collection for fertilizer production is lack of infrastructure.  The sewer system is not designed to separate urine from other waste.  In addition, the team is working on processes to remove pathogens and contaminants (residual pharmaceuticals, toxins, etc…), so that it can be safely used on crops.

  • Nancy Love is the principal investigator for UM's Urine Diversion research project.  She and her team are also conducting social research to determine ways to overcome the “ick” factor, and engaging in social research and market research to understand how the public and relevant stakeholders such as farmers, regulators, wastewater treatment plant personnel, and legislators perceive urine-derived fertilizers.

UM Project to Create Fertilizer from Urine

Urine contains nitrogen, phosphorus, and potassium—nutrients that are essential for plants to grow.  That’s why Professors Nancy Love, Krista Wigginton, and their team have installed special toilets and urinals at a University of Michigan building to divert urine, concentrate it, sanitize it, and prepare it for re-use as fertilizer.

Special Bathrooms on UM Campus

The special bathrooms at U-M include a urine-diverting toilet and a urine-diverting urinal.  The urine flows through a series of pipes into the Urine Processing Room in the basement of the building.  No solid waste (feces) reaches the Urine Room.  The urine goes through a series of processing steps that serve to concentrate it, sanitize it, and prepare it for re-use as fertilizer.

Problems from Human Urine “Effluent” in the Environment

Normally, when urine enters the wastewater stream, it carries with it the majority of the nitrogen, phosphorus, and potassium that people take in when they eat.  Many wastewater treatment plants do what they can to remove these nutrients before the wastewater effluent reaches water bodies since these nutrients, though important for plant growth, can cause eutrophication, hazardous algal blooms and fish kills when they reach bodies of water in high concentrations.  Unfortunately, the processes used to remove nutrients can be costly and energy-intensive.  Further, not all treatment plants are equipped to remove nutrients, and would need significant (and expensive) upgrades to meet environmental protection needs.

The project team is assessing if diverting urine will be a less energy intensive and more cost-effective way to reduce the nutrient loads in wastewater effluents and create fertilizer for agriculture.

For the past 4 years, the University of Michigan research team has been collaborating with the Rich Earth Institute, a non-profit research institute in Brattleboro, VT.  Rich Earth has been using urine and its products as fertilizer since 2012.  Working together, the Michigan and Vermont teams are studying the effectiveness and safety of using urine-derived products as fertilizer for all kinds of crops.  In order to do so, researchers have developed several different processing methods with the goal of removing trace pharmaceuticals and pathogens.

In 2018, the team is comparing several different urine-derived fertilizers to conventional fertilizers.  Using lettuce, carrots, and hay as test crops, they are comparing the efficacy, safety and environmental impacts of urine-derived fertilizers and conventional fertilizers.

Additionally, they are engaging in social research and market research to understand how the public and relevant stakeholders such as farmers, regulators, wastewater treatment plant personnel, and legislators perceive urine-derived fertilizers.

Why Urine?

[Krista] Wigginton, [Co-Principal Investigator on the UM Urine Diversion project], 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.

Less “Ick”

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.” 

Understanding Public Perceptions About Urine as a Source of Fertilizer

"It's possible that when people are asked to contribute to a system where their urine is diverted and used as fertilizer they might feel a little queasy about this at first," Michigan engineering professor Krista Wigginton said after cutting a ceremonial ribbon outside the women's restroom.  "And, so, a large part of this project is actually on the social science side, the education side, whether people are willing to adopt it.  And if not, what can we teach them about this problem and this solution so that they're more accepting of this type of solution."  The multi-state research effort is part of a $3 million National Science Foundation-funded project that's billed as the country's largest program examining the technological requirements and social attitudes related to urine-based fertilizers.

Michigan researchers, who are working with colleagues at the Vermont-based Rich Earth Institute and the University at Buffalo, say deriving fertilizer from nutrient-rich urine could save money and reduce pollution.  As for visitors to the side-by-side restrooms in the Brown building, Wigginton says they won't find anything out of the ordinary.  "I think the experience of using the toilet really isn't any different," she said, holding the stall door open and pointing at the split-bowl toilet. "That's part of the goal here: We don't want to disrupt what people are used to.  "We tried to make it as normal as possible." 

Fertilizer Stats and Environmental Effects

According to the USDA, “The global population is projected to reach 9.7 billion by 2050 and we will have to grow a lot more food to feed all of those people.  Some might think we would need to use a lot more fertilizer; however, too much fertilizer—nitrogen and phosphorus—can be disastrous to ecosystems, affecting the water, land, air, and biodiversity.  The nutrient challenge is to improve fertilizer efficiency to produce more food and energy crops while creating less pollution.

Each year farmers apply millions of tons of manufactured fertilizer, of which 40-80 percent is lost to the environment.  Unfortunately, fertilizer run-off that ends up in lakes, rivers, and estuaries can lead to eutrophication, which is harmful to the ecosystem.  Eutrophication is a process where fertilizer stimulates dense marine and freshwater plant growth, which can lead to the death of animal life due to lack of oxygen.  Eutrophication is responsible for the 2014 algae bloom in Lake Erie that poisoned drinking water in Toledo, Ohio.

At sea, eutrophication may lead to dead zones; there are nearly 500 eutrophic and hypoxic (low oxygen) zones around the world, including 12 in the Chesapeake Bay.  Excess fertilizer also plays a role in acidification and is linked to unhealthy bleached coral.”

Nancy Love

Dr. Nancy Love is the principal investigator for UM's Urine Diversion research project.  She is a Borchardt and Glysson Collegiate Professor in the University of Michigan Department of Civil and Environmental Engineering.  She has published more than 20 research publications related to the removal of contaminants from waste, and the connections between these chemical stressors and water quality.

According to her UM bio page, her research interests are “focused on environmental biotechnology and water quality with an emphasis on engineered treatment systems.  My specific interests focus on the fate of chemical stressors in these systems (e.g., toxins, pharmaceuticals, trace contaminants), the use of technologies to sense and remove these chemicals, antibiotic resistance, and on resource recovery from wastewater.  My research has been funded by the National Science Foundation, the Water Environment Research Foundation, The Cooperative Institute for Coastal and Estuarine Environmental Technology, various utilities and water authorities, and NASA.” 

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— David Fair is the WEMU News Director and host of Morning Edition on WEMU.  You can contact David at 734.487.3363, on twitter @DavidFairWEMU, or email him at dfair@emich.edu