New way to get nitrates out of wastewater found
Scientists at the University of Auckland have discovered new microbes that could cut carbon emissions from wastewater treatment. The team, led by Associate Professor Wei-Qin Zhuang, identified bacteria capable of converting harmful nitrate into harmless nitrogen gas more efficiently than traditional methods. Their findings offer a cleaner way to process both domestic and drinking water contaminated by excess nitrate.
The research began in 2023 when Zhuang’s team uncovered microbes from the Candidatus Krumholzibacteriota group. These bacteria break down ammonium in wastewater without producing carbon dioxide or nitrous oxide, the usual by-products of nitrate removal. Instead, they use organic carbon sources to speed up the process, reducing costs and complexity.
Human urine is the main source of nitrate in domestic wastewater. If untreated, nitrate can pollute rivers, triggering algae blooms and harming ecosystems. Earlier this year, a survey revealed that 5% of private bore water samples exceeded New Zealand’s nitrate safety limits, raising health concerns. The newly discovered microbes can be grown in labs and reintroduced into bioreactors. Some strains even use hydrogen gas or sulphur to remove nitrate, avoiding the need for energy-intensive chemicals. Zhuang’s team is now testing these systems in partnership with water utilities and industry groups, aiming for nationwide adoption. Beyond wastewater, the technology could help small communities and landowners treat nitrate-contaminated drinking water. Trials are underway to refine the process before wider use.
The microbes provide a low-carbon alternative to conventional nitrate removal. If scaled up, they could lower greenhouse gas emissions from water treatment while improving public health. The next step involves expanding real-world trials to confirm their effectiveness across different water systems.
