(ORDO NEWS) — The next time you water your plants, consider these seemingly disparate facts: First, plants need nitrogen, phosphorus, and potassium. Second, most of the nitrogen and phosphorus in wastewater comes from human urine, and your urine also contains potassium.
To be clear, we don’t advise you to go out and urinate on your tomatoes and zinnias. But if you did, it wouldn’t hurt them; in fact, pouring urine into the soil around your plants can help greens grow. Human urine could even reduce our dependence on chemical fertilizers if used in agriculture around the world.
The OCAPI organization in France works to improve food systems and human waste management and is therefore interested in alternatives to the overuse of chemical fertilizers in agriculture because the latter contribute to environmental pollution.
Nitrogen emitted from the production of fertilizers, weapons, and the burning of fossil fuels has doubled the amount of excess nitrogen compounds worldwide over the past 100 years. About 80% of nitrogen from agricultural use is leached into soil and water bodies, damaging ecosystems.
Now Paris, the capital of France, is about to put urine to a special test. The state planning office Paris et Metropole Amenagement wants to install urine-diverting toilets in the city’s “eco-block”, which has shops and 600 housing units.
The urine will be collected and used to fertilize green spaces in the city. Elsewhere in Paris, the European Space Agency plans to equip its French headquarters with 80 urine-diverting toilets.
Other pilot projects to turn urine into usable nutrient-rich water are already underway in Switzerland, Germany, the US, South Africa, Ethiopia, India, Mexico and France. Sweden even launched it back in the 1990s in a few villages.
However, the extension of the process to large cities or entire regions of the world requires a complete reconstruction of the wastewater infrastructure. It’s not an easy proposition, Julia Kavicki of the US Rich Earth Institute tells Tech Xplore.
Sanitation processes will need to be upgraded or replaced to separate urine treatment, bacteria removal and purification. The world will need urine many times the weight of today’s chemical fertilizers, she says. And the toilets themselves need to be changed to separate the flow of clean urine from solid waste.
Smaller regional experiments are being planned or already underway around the world. The developers behind these efforts hope to learn from experience how to create a viable alternative to chemical fertilizers.
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