Source separating toilet at University of Michigan
As water scarcity continues to be a global challenge, we must explore various pathways to close the water consumption cycle at the nexus of food, water, and energy systems. Consequently, the water sector has begun to incorporate nutrient recovery into wastewater treatment processes. One technology to consider is urine diversion or the separation of the human waste stream into its liquid and solid components. When separated, the nutrients in each component can be processed into fertilizer components more efficiently. Use of urine-derived fertilizers (UDFs) can reduce the energy and water demands of phosphorus mining and the Haber-Bosch process, which fixes atmospheric nitrogen into ammonia. Urine diversion also results in a concentrated waste stream from which contaminants can be more effectively removed.
Although urine diversion is not novel, it is a foreign idea to many communities. One of which is Switzerland, where the concept has been studied to determine the feasibility of implementing the technology on a large scale. Large programs are now also underway in Paris, France, Sweden, and in the PAE Living Building in Portland, Oregon. Some challenges that were identified include public perception of using urine as a fertilizer, understanding the fate and removal methods of pharmaceuticals and viruses in the urine, and the environmental impacts of applying UDFs.
Abe Noe-Hayes and Nancy Love cut the ribbon on the source-separating bathrooms in the EWRE building at the University of Michigan
the University of Michigan, along with partners at the Rich Earth Institute and University of Buffalo’s RENEW Center, have been studying how to safely create UDF and scale source separation programs. The team has secured almost $5 million in research funding. Spin off Brightwater Tools is now manufacturing and selling equipment to process human waste for regenerative sanitation.
The University of Michigan’s Urine Processing Room in GG Brown (north campus) was upgraded in April 2024 to include both a freeze concentrator (center) and pasteurizer (right wall) from Brightwater Tools. The system is controlled remotely and is highly automated. At full weekday production, we can process 50 liters of source separated urine a day, resulting in 150 to 200 pounds of nitrogen recovered per year.
