Sewage is rarely thought of as a valuable resource, but the Green Urine campaign aims to change that–by utilizing urine for phosphate fertilizer and raising awareness of its benefits. The phosphates from urine will be extracted and turned into struvite, an agricultural fertilizer.
The campaign uses highly visible outdoor urinals in Amsterdam’s La Place de la Bourse as collection sites and introduces the question: Is our wastewater actually a goldmine?
Urine was collected by the city’s water company, Waternet, then upcycled to fertilize green roofs as part of International Water Week, which aims to create “integrated solutions for a green economy.” This event aims to raise awareness about water issues and explore solutions, such as industrial and municipal water reuse and technology for optimizing the water cycle. Although publicly collecting urine may seem comical, it was a serious campaign aimed at raising awareness about waste reduction and the possibility of using urine as a source of phosphates for agricultural use.
Waternet is rising to the challange by constructing a facility that will make 1,000 tons of fertilizer from the wastewater of 1 million people. The facility is expected to open later this year.
Concern of phosphorus shortage could impact agriculture
Farmers largely use mined phosphorus to fertilize crops, previously using compost and manure to provide this vital nutrient. Unfortunately phosphorus fertilizer ends up in our waterways, where it produces algal blooms that suck up oxygen and create dead zones. Some scientists are concerned that phosphorus resources used for making fertilizer will run out in the next 50 to 100 years. They expect peak phosphorus in 2030, creating soaring food prices, while undermining our ability to grow food. Although this concern of peak phosphorus is debatable, if nothing else, using urine in fertilizer could hedge against rising fertilizer prices and produce a new revenue stream for Amsterdam and beyond.
Urine to the Rescue
Urine can be used directly on plants when diluted with water, providing nitrogen, phosphorus and potassium–the main nutrients plants need to thrive. Because urine is sterile, it doesn’t pose a microbiological risk. The use of urine as a fertilizer has been described as an “age-old tradition” in Nepal. Hari Krishna Upreti, senior scientist at the Nepal Agricultural Research Council’s Botany Division, recommends using urine and compost together for the best results.
The cross-contamination with feces, however, can create sanitation problems–as feces needs further processing, particularly before being used on food. It is recommended to separate urine from feces to ensure sanitation. Ecosan toilets help make the process both simple and sanitary, while saving water. The technology enables human waste to be used safely as fertilizer, mitigating reliance on chemical fertilizers.
If you consider the volume we’re talking about on a global scale, the potential is huge. “A person urinates an average of 550 liters per year,” says Upreti. “So this produces some four kilograms of nitrogen, which is equivalent to eight kilograms of nitrogen-rich urea.”
The concept of using human waste as fertilizer is still taboo in many parts of the world, making the highly visible outdoor urinal display in Amsterdam intriguing, as it pushes the envelope. Creating more sustainable systems will sometimes require questioning our norms and creating new ways of doing things…gee whiz!
Image credit: Chris Toala Olivares via AGV.nl
Sarah Lozanova is a regular contributor to environmental and energy publications and websites, including Mother Earth Living, Green Building & Design, Triple Pundit, Urban Farm, and Solar Today. Her experience includes work with small-scale solar energy installations and utility-scale wind farms. She earned an MBA in sustainable management from the Presidio Graduate School and she resides in Belfast Cohousing & Ecovillage in Midcoast Maine with her husband and two children.