Researchers from Tokyo University found a way to create urine-derived fertilizer that is fit for space farming.

One of the biggest challenges facing long-term human settlement on Mars is achieving the autonomy needed that would allow colonies to survive a catastrophic failure in provisioning. The key to achieving this is by ensuring food sufficiency and self-sustenance.

The team hopes to spearhead technology development for safe and sustainable space agriculture. For this study, the team focuses on food production in closed environments.

Farmers use animal waste as fertilizer because it is a rich source of nitrogen. Researchers explored the possibility of manufacturing fertilizer from the urea to make liquid fertilizer. Not only would this help grow food in space, but it would also address the problem of human waste treatment or management in space.

Manuring with man urine: researchers from Japan electrochemically create ammonia from urine to grow plants in space.Source: FreepikManuring with man urine: researchers from Japan electrochemically create ammonia from urine to grow plants in space.Source: Freepik

The team's new method uses an electrochemical device that derives ammonium ions from an artificial urine sample. On one side of the device, there is a reaction cell with a boron-doped diamond (BDD) electrode and a light-inducible catalyst or photocatalyst material made of titanium dioxide. The second side has a counter cell with a platinum electrode. A current is passed into the reaction cell, urea is oxidized and ammonium ions are formed, and electrochemically produced liquid fertilizer is created.

The team wondered if the cell would be more efficient with a photocatalyst. To do this, they compared the reaction of a cell with a photocatalyst and a cell without it. They found that the initial depletion of urea was more or less the same between the two cells. Nitrogen-based ions produced varied results in time and distribution when a photocatalyst was introduced. The concentration of nitrate and nitrate ions was not as elevated in the cell with the photocatalyst. These results suggest that the presence of a photocatalyst promoted the ammonium ion formation.

The team plans to perform more experiments with actual urine samples. They believe this will work because the artificial urine and real urine have the same primary and secondary elements needed for plant nutrition.

The study was published in the New Journal of Chemistry.