Who Would Have Thought Urine Can be Useful

Global phosphorus reserves are also shrinking and farmers around the world have faced shortages with soaring prices since Russia, a major fertilizer exporter, invaded Ukraine. Scientists have long valued the resources found in human waste as a way to reduce dependence on imports.

"When there is a shock in the supply chain, how do we grow food? Recycling urine increases the resilience of our food system," said Prithvi Simha, researcher at the Swedish University of Agricultural Sciences (SLU).

About a third of all nitrogen and phosphorus used in agriculture globally could potentially be replaced by nutrients obtained from urine, according to Simha.

This percentage grows dramatically for countries such as Uganda or Ethiopia, where there is a large population to provide urine, but not much synthetic fertilizer is used because it’s too expensive.

Simha is part of a research team that developed a way to convert urine into a solid fertilizer that is smaller in volume and looks like the synthetic pellets that most farmers use today.

SLU's spin-off company, Sanitation 360 based in Sweden's Gotland Island is equipping toilet with cassettes that make urine alkaline. This process allows the nutrients it contains to remain stable while a fan evaporates the water, leaving behind a dry powder.

"There's quite a lot of complex chemistry behind how we make this happen, but in reality, it's pretty simple to implement," said Simha.

Sanitation 360 has partnered with a company that rents out portable toilets. This step increases urine collection from 1.500 liters to 25.000 liters and next year, 250.000 liters are targeted to be achieved.

If urine fertilizer wants to become mainstream, it must be able to compete with synthetic fertilizers that are mass-produced. 

Those efforts include getting certified by national regulators because some parts of the world still label urine separated from its source as waste.