A world-first trial of floating wetland pods in wastewater lagoons has demonstrated that nature-based solutions can slash overall greenhouse gas emissions by more than a quarter, offering a low-tech pathway to decarbonise the water sector.
The two-year study, conducted by RMIT University, Westernport Water, and Australia’s national science agency CSIRO, monitored a 330-square-metre floating platform of native reeds and sedges installed at a wastewater lagoon on Phillip Island in south-east Victoria.
Published in the Journal of Environmental Management, the research revealed dramatic reductions compared to a control lagoon without a wetland platform.
Carbon dioxide emissions dropped by up to 36 per cent, methane decreased by up to 66 per cent, and nitrogen fell by 18 per cent.
Lead author Dr Lukas Schuster, from RMIT University, highlighted the significance of using plant root systems to foster emission-reducing microbial communities.
“This is the first time we’ve had evidence on this scale that supporting microbial communities in the root systems of wetland plants can reduce wastewater emissions without relying on high-tech solutions,” Schuster said.
“It’s a strong demonstration of how nature-based approaches can transform wastewater treatment into part of the climate solution.”
With global wastewater treatment accounting for approximately 1.6 per cent of human-induced greenhouse gas emissions, the trial provides a scalable mitigation option for water utilities.
Westernport Water Managing Director Dona Tantirimudalige noted that floating wetlands can be retrofitted directly into existing lagoon infrastructure without requiring major operational overhauls.
CSIRO Research Scientist Dr John Awad added that the technology also captures contaminants, improving water quality prior to discharge.
“As well as mitigating greenhouse gas emissions, floating wetlands also help tackle contaminants, improving water quality before it’s discharged into downstream ecosystems,” he said.
Building on the Phillip Island results, RMIT researchers have partnered with Melbourne Water and the Bass Coast Landcare Network to trial floating wetlands in farm dams across Victoria’s Bass Coast, exploring broader applications for agricultural productivity and biodiversity.