Human urine could be used to make fertilizers
Fotokostic / Getty images
A more effective way to extract fertilizer from human urine could help better use wastewater in cities and farms, without exacerbating global warming.
Human urine is rich in useful compounds for cultivation cultivation, such as nitrogen, but chemical processes to extract these compounds are less effective than industrial fertilizer manufacturing methods, such as the Haber-Bosch process, which converts nitrogen into ammonia air by adding hydrogen. However, these methods are often at high energy intensity and produce climate pollutants.
NOW, Xinjian Shi At Henan University in Kaifeng, China, and his colleagues discovered that adding oxygen from air and a graphite catalyst for urine produces a chemical rich in nitrogen called Percarbamide. The process requires only a few steps and produces no waste.
“Before our method, the traditional method of separation (the compound rich in nitrogen) of urine urea was to concentrate urine to precipitate urea and inorganic salts, then purify urea by exploiting the differences in solubility,” explains Shi. “This process is heavy and the resulting purity is low.”
Shi and his team placed thin graphite leaves, which had been modified to have faults in the way their atoms were joined, on an electrode. This was then placed in a concentrated solution rich in urea.
When they passed electricity Thanks to the solution, solid percarbamide crystals have formed, made from oxygen in the air, hydrogen of water and urine urea. These crystals could then be easily separated from the liquid solution.
Then, the team tested how percarbamide works like a fertilizer and found it that it helped wheat, peanuts and higher lettuce plants than when they were cultivated with normal water or fertilizer. Shi says it may be due to the fact that percarbamide can regularly release oxygen and helps control nitrogen levels in ground.
James McGregor At the University of Sheffield, in the United Kingdom, said that the approach could be used for other chemical processes, but it could be difficult to evolve in the treatment of wastewater on the city level.
“I would be surprised if we were seated here in 10 years and it was a major industrial process, but it has potentially applications for decentralized, local and small-scale production, probably in particular in agricultural circles,” he said.
