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.
Ann Arbor, MI
Number of students at U-M
9 Billion Pounds
Amount of chemical fertilizer that could be replaced with the urine Americans produce each year
Increase in phosphorus fertilizer price between 1993 and 2013
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.
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.
As part of their research, the team has created two animations that describe the potential power of pee. Take a look below!
Full-length Video (6:33)
Abbreviated Video (3:44)
To learn more about this project, please contact Audrey Pallmeyer, Research Manager, at email@example.com.