Floating wetland cuts methane from Australian wastewater lagoon by up to two-thirds

A two-year field trial on Phillip Island, Victoria, tested a 330-square-metre floating wetland built from native reeds and sedges on a municipal wastewater lagoon. The platform, monitored by a solar-powered sensor system, lowered methane emissions by up to 66 % and reduced carbon dioxide and nitrous oxide by 36 % and 18 % respectively, compared with an untreated control lagoon. Researchers said the plant roots fostered microbial communities that broke down gases and filtered heavy metals, even though overall nutrient levels stayed similar.

The findings suggest utilities could meet net-zero goals by adding such nature-based solutions to existing lagoons rather than rebuilding facilities. Westernport Water’s managing director highlighted the potential for broader testing across different lagoon types. Follow-up trials are now underway on farm dams in the Bass Coast region to see if similar benefits occur on agricultural sites.