Scientists are aiming to tackle a global shortage of phosphorus (P) by extracting it from human urine, as part of a new study at the University of Surrey.  

Maano Tshimange, Researcher at Surrey’s School of Chemistry and Chemical Engineering, said:  

“Within 50-100 years, we will run out of phosphate rock to mine. That will threaten our supply of fertilisers, making it harder to feed the growing global population. 

“Getting phosphorus from urine could be a simple, cheap alternative. And let’s face it, there’s so much of it available that we'll never be caught short. Human urine alone could provide as much as 11% of the world’s phosphorus needs.” 

Scientists will collect 15 litres of urine from volunteers at toilets across the University’s Guildford campus.  

They will extract phosphorus by passing the urine through a special membrane, allowing the water to pass through while leaving the phosphorus on the other side. This energy-efficient process is called forward osmosis.  

Although urine is already used as a fertiliser in some rural communities, it is inefficient and costly to transport, because it is made of 97% water. For that reason, concentrating the urine using this technique could be more effective.  

The researchers will study how efficiently the membrane extracts phosphorus.  

They will also investigate how best to prevent the urine from fouling the membrane and clogging up its pores.  

The study is expected to last until summer 2025.