Researchers from Cornell University’s College of Agriculture and Life Sciences and the Canadian Light Source (CLS) at the University of Saskatchewan have proven it is possible to create nitrogen-rich fertilizer by combining the solid and liquid components of human waste. The discovery, published recently in the journal Sustainable Chemistry and Engineering, has the potential to increase agriculture yields in developing countries and reduce contamination of groundwater caused by nitrogen runoff.
Special separating toilets that were developed through the Reinvent the Toilet Challenge have helped solve long-standing sanitation problems in the slums of Nairobi, Kenya. However, the methods used to dispose of the two outputs failed to capture a key nutrient that local fields were starving for: nitrogen.
Cornell researchers Leilah Krounbi, a former PhD student, now at the Weizmann Institute in Israel, and Johannes Lehmann, senior author and professor of soil and crop sciences, wondered whether it might be possible to close the waste stream loop by recycling nitrogen from the urine, which was otherwise being lost to runoff. While other researchers have engineered adsorbers using high-tech ingredients such as carbon nanotubes or activated carbons, Lehmann and his team wanted to know if they could do so with decidedly low-tech materials like human feces. Adsorbers are materials whose surfaces can capture and hold gas or liquids.
Read more on the Canadian Light Source website
Image: The researchers used the SGM beamline at the CLS to see how the chemistry in the nitrogen changed as it adsorbed ammonia and how well their material could make nitrogen available to plants if it was used as a fertilizer.