Public urinals harness pee to grow food

The Netherlands' Waternet utilities company has placed some pee-collecting urinals in Amsterdam, with the hope of turning it into fertilizer for the city's urban roof gardens.

How much use is a city-load of urine? Quite a lot, it turns out. So much so that the Netherlands’ Waternet utilities company has placed some pee-collecting urinals in Amsterdam, with the hope of turning it into fertilizer for the city’s urban roof gardens.

The idea stems from the fact that urine contains phosphorous, a key ingredient in for fertilizer that is a non-renewable resource facing depletion. Urine also causes issues for companies like Waternet, because the phosphorous crystallizes and clogs up pipes. As a solution to both problems, the company places public urinals in a park in Amsterdam. Rather than sending the wastewater through sewage pipes like traditional lavatories, the pee is instead collected and sent to a recovery plant, where the phosphorous is filtered and turned into struvite fertilizer. The campaign coincides with new Dutch laws that enables the agriculture industry to use human waste on farms. Waternet’s fertilizer will be used to give back to the city, with urban rooftop farms benefitting.

Although it may seem an odd campaign, it’s not the first to embrace public peeing for eco causes. The Xixi Elétrico project in Brazil also harnessed the power of urine streams to control dynamos that provided the electricity for carnival speakers. Are there other ways that a substance typically considered as waste could become more useful?