Diverting urine away from municipal wastewater treatment plants and recycling the nutrient-rich liquid to make crop fertilizer would result in multiple environmental benefits when used at city scale, according to a new University of Michigan-led study.
The study, published online Dec. 15 in the journal Environmental Science & Technology, modeled large-scale, centralized urine-diversion and fertilizer-processing systems—none of which currently exist—and compared their expected environmental impacts to conventional wastewater treatment and fertilizer production methods.
The researchers found that urine diversion and recycling led to significant reductions in greenhouse gas emissions, energy use, freshwater consumption and the potential to fuel algal blooms in lakes and other water bodies. The reductions ranged from 26% to 64%, depending on the impact category.
“Urine diversion consistently had lower environmental impacts than conventional systems,” said lead author Stephen Hilton, who conducted the study for his master’s thesis at U-M’s School for Environment and Sustainability.
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