Wastewater nitrate turned into ammonia in Chinese lab breakthrough

Nearly three times more efficient than existing alternatives, a new dual-atom catalyst developed by a Chinese research team can transform nitrate-laden wastewater into ammonia—a core ingredient in urea fertilizer. The process promises to be cheaper and more energy-efficient than current methods, turning a serious pollutant into a valuable resource.

Agricultural runoff, animal waste, chemical plant discharge, and sewage treatment all contribute to high nitrate levels in wastewater. When released unchecked into the environment, the excess nitrogen can trigger algal blooms that deplete oxygen in waterways, creating dead zones where fish and other aquatic life cannot survive. Groundwater contamination from nitrates also poses health risks to humans and animals.

Conventional wastewater treatment removes nitrate but at a high cost in energy and money. The Chinese team saw an opportunity: nitrate is rich in nitrogen, the same element that makes fertilizer effective. Their work aims to capture that nitrogen and recycle it directly into ammonia.

Waste-to-fertilizer breakthrough

Ammonia is one of the world’s most important industrial chemicals, used in fertilizers, explosives, refrigerants, and potential hydrogen energy systems. Producing it today typically relies on the Haber–Bosch process, which combines pure nitrogen and hydrogen under extreme temperatures and pressures—conditions usually achieved by burning natural gas. That process alone consumes an estimated 1–2% of global energy.

Making ammonia from waste nitrate instead could cut pollution, lower energy use, and reduce dependence on imported feedstocks. The result would be a form of circular fertilizer production.

The breakthrough centers on a new super catalyst. Unlike traditional catalysts that use single atoms or nanoparticles, the Chinese team employed a dual-atom catalyst (DAC). For multi-step reactions like converting nitrate to ammonia, two complementary atoms working together—an atomic “tag team”—better facilitate electron transfers, intermediate molecule handling, and bond breaking and forming.

More work needed

Artificial intelligence helped the researchers identify the best atom pairs to test, saving countless hours of trial-and-error physical experiments. The payoff: the catalyst is nearly three times more efficient than comparable catalysts, according to the team. That translates to higher ammonia yields, better conversion rates, and less waste.

Still, the work remains at the laboratory stage. The team has demonstrated the catalyst only in small batches under controlled conditions. It has yet to be proven whether the process can scale to real-world applications, handle the varying contaminants found in actual wastewater, or maintain performance over time.

The full study appears in the Journal of the American Chemical Society.