Liquid gold: Could we turn our urine into fertilizer?
For thousands of years, human urine has had real value. After our bodies absorb nutrients from our food, they excrete the rest—mainly via urine. An adult produces about 500 liters (132 gallons) a year. This liquid gold is very rich in nitrogen, phosphorus and potassium, three nutrients vital for plant growth.
For centuries, human urine has been recognized as a valuable resource, providing essential nutrients like nitrogen, phosphorus, and potassium for plant growth. Ancient civilizations such as Greece, China, and Rome utilized urine as fertilizer alongside animal feces. In modern times, synthetic fertilizers have largely replaced natural fertilizers like urine, with half of the world's population relying on food grown using these artificial alternatives.
However, the increasing cost of synthetic fertilizers, particularly due to the ongoing Iran war, has sparked interest in turning urine back into a viable fertilizer option, a concept known as "pee-cycling."
Urine is rich in nutrients and contains nearly all the nitrogen and half the phosphorus found in wastewater. Separating and treating urine before it enters wastewater treatment plants could recover these valuable nutrients, reducing treatment emissions and minimizing pollution. On a small scale, specialized urine-diverting toilets and urinals can capture raw urine, which can then be applied directly to home gardens following proper guidelines.
On a larger scale, urine-based fertilizers have been successfully utilized in various communities worldwide. The Rich Earth Institute in the United States has been leading community peecycling programs for over a decade, while Swiss startup VunaNexus and sporting arenas in the UK, Sweden, and South Africa are also exploring the use of diverted urine as a sustainable fertilizer. In Australia, researchers are conducting trials in Brisbane and Sydney parklands.
Despite its potential, scaling up urine-based fertilizers faces several challenges, including the "ick factor" and the need to address issues related to pathogens, pharmaceuticals, inconsistent plumbing codes, and public acceptance. To overcome these obstacles, dedicated infrastructure, strict contaminant control, robust regulation, and increased public acceptance will be necessary.
Ultimately, the potential of urine as a sustainable fertilizer source could prove crucial in an increasingly uncertain and resource-constrained world.
Written by urgent.news from Phys.org's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
