Human urine, an unexpected but effective and less polluting fertilizer

What to replace it? Polna researchers have answered including Fabian Escolier, who has never forgotten his grandmother’s advice and is considering overhauling more sustainable diets. In order to grow, “plants need nutrients, nitrogen, phosphorous and potassium,” explains engineer and coordinator of the OCAPI Research Program in France. When we eat, we take in these nutrients before we “excrete them, mostly via urine,” he continues. For a long time, urban waste was used in agricultural fields, before it was replaced by chemical fertilizers.

Many experiences

But when these nutrients are released in very large quantities into rivers, they promote an explosion of green algae, for example, and represent “a major source of nutrient pollution,” asserts Julia Cavici, of the Rich Earth Institute, based in the USA. Separating and collecting urine from the source requires rethinking the toilets and collection network and overcoming some preconceptions. Separation of urine from toilets was tested in Swedish eco-villages in the early 1990s, and then in Switzerland or Germany.

Trials are taking place in the United States, South Africa, Ethiopia, India and Mexico. In France, projects appear in Dol-de-Bretagne, Paris, Montpellier. “It takes time to introduce environmental innovations, especially one as radical as urine separation,” says Tove Larsen, a researcher at the Swiss Federal School of Water Science and Technology (Eawag). She explains that the first generations of urine-separating toilets, considered impractical and ugly in appearance, may have served as brakes. The researcher hopes that a new model developed by the Swiss company Laufen together with Eawag should solve these difficulties.

Fabien Gandousi owns Restaurant 211 in Paris, which is equipped with dry toilets where urine is collected. “We have pretty positive vibes, people who are a little surprised, but […] They see little difference from the traditional system.” Marin Legrand, anthropologist and member of the Okapi Network, comments, “There are obstacles to overcome.” But “we begin to understand how precious water is” and “defecating within it becomes unacceptable.”

about the same topic

Food: Why is organic good for your health?

In 2020, a total of 6.5% of the average basket of French people was made up of organic products, and 13% of French people said they consume at least one organic product per day. According to Agence Bio, since the health crisis, an increasing number of French have confirmed taking more time to cook (55% in 2020 compared to 47% in 2019), with an increase particularly reported among those under 35. Waste reduction, consumption of fresh and local produce also increased in the general population, and slightly more importantly among adherents of organic matter compared to non-organic.

“This topic touches on intimacy”

Are people still ready to eat urine-enriched foods? The study shows marked differences between countries. The acceptance rate is very high in China, France or Uganda, but low in Portugal or Jordan. “This topic touches intimacy,” analyzes Ghislain Mercier, of Paris and the Métropole Aménagement which is developing an eco-zone in Paris with 600 housing units and shops…Urine will be collected there and fertilize Parisian green spaces.

According to him, there is great potential in offices and homes that are not connected to the sewage network or slums that do not have sanitation facilities. However, it is necessary to compel the population, to rethink the pipes, to counteract inappropriate legislation … Once the urine has been harvested, the urine must be transported to the fields, which is costly. Various technologies make it possible to reduce its volume and concentration of urea or even dry it. Rich Earth Institute develops technology solutions to make spreading this fertilizer easy and inexpensive for farmers.

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