Kompotoi, ogmo and VaLoo build first public circular toilet

(CONNECT) The Circular Toilet team completes the first fully circular toilet for the public that recycles separately collected urine into nutrient-rich plant fertilizer on site. According to a press release, the joint project by Kompotoi from Winterthur, ogmo from Dübendorf and the Zurich association VaLoo is using the prize money of 30,000 Swiss francs that it received at the end of October as the winner of second place and the audience prize at the Clima Now Spotlight Award 2025.

At the heart of the Circular Toilet is ogmo's Nutrient Harvester technology, which is integrated into the Kompotoi Piazza, a modular and barrier-free composting toilet. This water-free technology was developed by the aquatic research institute Eawag and is now being driven forward by its spin-off ogmo, which was founded in 2025.

The first step is to collect and stabilize the urine in order to eliminate odours and germs. Then 95 percent of the water is removed from the mass and the remaining material is dried. The concentrate is then turned into a granulate that serves as a nutrient-rich plant fertilizer. In addition, service water is produced which, although not yet of drinking water quality, can already be used to irrigate green spaces or simply seep away.

The team behind this pioneering project is now looking for a partner municipality to install this first system. In September 2025, the City of Zurich launched a test operation at the ZüriWC Schindlergut site.

"With this toilet, we are showing that a genuine circular economy also works in public spaces," says Kompotoi co-founder Jojo Casanova. "Municipalities and cities can easily make the sanitary facilities they already need greener. Our vision is to turn something as commonplace as going to the toilet into a sustainable contribution to the environment." ce/mm