An international study, co-led by Prof Stefan Wuertz, Deputy Centre Director of SCELSE, has created the world’s largest and most detailed catalogue of microbes for use in wastewater treatment plants (WWTPs). Published in Nature Water on 23 Jan 2026, this study – Metagenome-resolved global microbial diversity and function in activated-sludge wastewater treatment systems – provides the first detailed look at the vast number of unknown microorganisms in WWTPs based on a global metagenomic dataset.

WWTPs rely on vast microbial communities to remove various pollutants, including nitrogen, phosphorus and organic compounds, from wastewater. Until now, scientists have lacked a global genome-level map showing which microorganisms are present and what they are genetically capable of doing. The team of researchers, from NTU Singapore and South China University of Technology, extracted and sequenced the DNA of microorganisms found in 125 wastewater samples from Singapore (44 samples) and China (81 samples). After further integrating 703 publicly available metagenomic sequencing datasets of wastewater sludge from six continents, they reconstructed more than 24,500 microbial genomes from almost 8,000 species. More than 12,500 new species and over 24 million unique genes were also uncovered.

This new microbial catalogue not only identifies species, but it also systematically maps their functional traits. Thus, it allows scientists to track the specific genes responsible for nutrient removal, plastic degradation, and even the potential biosynthesis of useful materials in these microbes. The catalogue will potentially guide the creation of new, more efficient, and climate-resilient microbial communities to clean wastewater.

Prof Stefan Wuertz, NTU Professor of Environmental Engineering and the co-corresponding author, said: “Because thousands of these genomes are accurately identified and specific to certain wastewater systems, scientists can now name unknown microbes, map their feeding habits, and see how they adapt and evolve over time in treatment plants. As such, this study is a big step forward in tackling growing global environmental challenges and making water treatment cleaner, cheaper, and more sustainable.”

By providing this global benchmark, the research lays the foundation for computer-modelling the biological processes of water treatment, paving the way for next-generation, high-tech water recycling.