The Science Journal Nature published an article this week on how pee can help save the world. According to the article scientists say that urine diversion would have huge environmental and public-health benefits if deployed on a large scale around the world. Human urine is rich in nutrients such as potassium, nitrogen and phosphorous and can be used to fertilise crops and feed into industrial processes. They estimate that humans produce enough urine to replace about ¼ of current nitrogen and phosphorous fertilizers worldwide. In Ireland, N and P are the most significant pressure polluting our waterways coming from agricultural use and from wastewater treatment systems.
There are many research projects going on across the world to separate urine from the rest of sewage and to recycle it into products such as fertilizer. The practice is known as urine diversion and is being studied in the USA, Australia, Switzerland and Africa. In Paris, there are plans to install urine-diverting toilets in a 1000 resident eco-quarter being built in the 14th district of the city. Scientists say that urine diversion has huge environmental and public-health benefits and that using dry toilets would also reduce the strain on aging and overloaded sewer systems.
Particularly as shortages arise in energy, water and raw materials for agriculture, urine has the potential to be a valuable resource. The amount of nitrogen fertilizer used in agriculture has climbed more than 8 times in the past 60 years and much of it is produced using energy intensive processes that rely on fossil fuels. A study carried out in the Unites States found that urine diversion could be ‘transformative’. They projected that communities using urine-diversion could lower their overall greenhouse-gas emissions by up to 47%, energy consumption by up to 41%, freshwater use by about half and nutrient pollution from wastewater by up to 64% depending on the technologies used.
However, there are obstacles such as designing and retrofitting urine-diverting toilets, treating urine and turning it into a valuable product and also the social change needed to accept using human waste within the food system. In the past, it has been used to fertilise crops, tan leather and for producing gunpowder. In Sweden, a trial where urine is dried and made into pellets that fit into a standard farm machinery is used as a fertilizer to grow barley that will go to a brewery to make ale. The research reports that a 2021 survey of people in 16 countries indicated that willingness to consume urine-fertilized food approached 80% in places such as France, Chine and Uganda.
The full article is available at: