Scientists turned urine into solid fertilizer: using it will make agriculture sustainable

Scientists turn human urine into soil fertilizer

The immediate future may be marked by more sustainable agriculture. It is likely that the food that ends up on the consumer's table will be grown on organic farms. The global food production system has a significant impact on the planet's natural nitrogen and phosphorus cycles. The yield is limited by these two chemical elements. They are applied to the soil as fertilizers. Almost all of them are produced by converting nitrogen from air to ammonia.

That process consumes up to two percent of the world's energy. It relies heavily on fossil fuels, as well as on the extraction of certain limited resources such as phosphorites. To solve this problem, the scientists decided to pay attention to the nutrients consumed by humans with food and excreted in urine.

The nutrients are washed off, diluted with water, end up in a wastewater treatment plant, where they are safely discharged into the environment. It turns out that some of the wastewater is rich in nutrients. That part consists of human urine, for a total of at least 1% of the total wastewater. That percentage contains about 80% nitrogen and about 50% phosphorus.

The researchers found out that urine can be processed and obtained valuable and environmentally friendly fertilizers for the treatment of agricultural areas. It is possible that for such purposes it will have to be collected using special dry closets.

To fertilize one hectare of land with it, farmers will need about 15 thousand kilograms of a substance containing processed human urine. The scientists believe that a way to extract nutrients from it is needed, and then only 400 kilograms of a new type of fertilizer will be needed for the same land area. It is difficult to evaporate urine from water.

The valuable nitrogen in it is in the form of urea, a special chemical that is used to produce nitrogen fertilizers all over the world. But there is also urease, a fast-acting enzyme that converts urea into ammonia.

Contacting with the air, ammonia quickly evaporates, and with it nitrogen from urine, emitting an extremely pungent odor. Using a special technology for alkaline urine dehydration, the researchers obtained a new fertilizer that can be actively used in the agro-industrial complex.