In Switzerland, a Startup Draws Inspiration from ESA to Grow Plants Using Your Urine

The path of our urine

Have you ever wondered where your urine goes when you flush the toilet? When you relieve yourself, urine is carried by the water from the toilet towards the drain pipes of your home towards the sewers.

Waste water from the sewers will arrive in a treatment plant, where it will be filtered and cleaned to get rid of impurities, bacteria and pollutants, in particular via biological treatment by micro-organisms (bacteria which will eat and decompose the pollutants).

Once the water is purified, it is released into nature such as rivers, lakes and sometimes into the sea. Our urine also contains nutrients like nitrogen, phosphorus and potassium, which will be eliminated in the sewage treatment plant.

However, the latter, in particular nitrogen, could be used for the good of plants.

Turn urine into fertilizer

Indeed, plants need nitrogen to make their proteins, develop their leaves and ensure photosynthesis. This nutrient is a sort of “natural fertilizer”.

Urine could therefore present an ecological source for obtaining nitrogen, rather than producing nitrogen fertilizers, which contribute to the phenomenon of global warming.

This is what Nadège and David de Chambrier understood, two Swiss brothers and sisters who founded “VunaNexus”, a start-up which transforms urine into fertilizer for plants by recycling its nutrients.

The process consists of conveying urine, via dry urinals or separate toilets, to a biological reactor. There, nitrification stabilizes it: two types of bacteria transform ammonium into nitrate, which eliminates the odor in just five to ten days.

A project inspired by ESA

After nitrification, the substance is filtered to remove micropollutants, pasteurized and concentrated by distillation. This process produces reusable distilled water and Aurin, the first European urine-based fertilizer. The system is fully automated, remotely controllable and requires little maintenance, explains the start-up on its website.

VunaNexus was inspired by ESA's MELiSSA project, which studies regenerative systems for long space missions. The idea is to recycle nutrients, like nitrogen and phosphorus found in urine, for reuse instead of throwing them out.

On Earth, VunaNexus applies this principle to reduce pollution, save water and close the human nutrient cycle. The start-up which is supported by the ESA, processes around 8000 liters of urine per day and has installed their sewage treatment plant in six projects, commercial and residential and one of the largest private banks in Switzerland, she explained.

“Our vision is that in the future, most large buildings in dense city centers will be equipped with technologies to recycle nutrients from urine ” said David.

Source: Popular Science