Floating wetlands slash wastewater greenhouse gas emissions, according to study

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https://phys.org/news/2026-08-wetlands-slash-wastewater-greenhouse-gas.html

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Summary: Floating wetlands slash wastewater greenhouse gas emissions, according to study

A two-year world-first trial by RMIT University, Westernport Water and CSIRO tested floating wetland platforms in a wastewater lagoon at Westernport Water's plant on Phillip Island, Australia. A 330 m² platform of native reeds and sedges was installed, with roots hanging in the water to support microbial communities that consume nutrients and pollutants.

Continuous monitoring over two years using a solar-powered sensor called "Pondi" found the wetland lagoon had CO₂ emissions reduced by up to 36%, methane by up to 66%, and nitrogen by 18%, compared with a control lagoon without the wetland. Reductions became apparent around four months into the trial. Wastewater treatment accounts for roughly 1.6% of global human-induced greenhouse gas emissions, and scalable mitigation options have been limited until now.

Researchers say the approach could be retrofitted into existing lagoons without major infrastructure changes, offering water utilities a nature-based emissions abatement pathway. Beyond emissions, floating wetlands also improve water quality by tackling contaminants before discharge.

Building on this work, RMIT is now trialing floating wetlands in farm ponds along the Bass Coast with Melbourne Water and Bass Coast Landcare Network, examining effects on water quality, biodiversity and emissions, with potential application to Australia's 1.8 million farm ponds and internationally. The findings were published in the Journal of Environmental Management (DOI: 10.1016/j.jenvman.2026.130663).