Floating wetlands prove effective in cutting greenhouse gas emissions

A groundbreaking trial on Phillip Island has shown that floating wetlands can significantly reduce greenhouse gas emissions from wastewater lagoons. The innovative technology, tested over two years, has paved the way for a more sustainable approach to wastewater treatment.

How it works

A 330-square-metre floating platform, planted with native reeds and sedges, was placed on a wastewater lagoon in Victoria's east. The plants' roots, hanging into the wastewater, created a habitat for microbes that help break down organic matter and absorb nutrients and pollutants.

"Floating wetlands are, you can imagine, like buoyant platforms that basically have the wetland plants planted onto them and the roots are hanging down into the water," RMIT's Centre for Nature Positive Solutions research fellow Lukas Schuster said.

The trial, conducted by RMIT University, Westernport Water, and the CSIRO, found that the floating wetland reduced carbon dioxide emissions by up to 36 per cent, methane by up to 66 per cent, and nitrogen by 18 per cent compared to a control lagoon without a wetland.

A significant source of emissions

Dr. Schuster said wastewater treatment was a significant source of emissions globally, producing roughly 700 million tonnes of greenhouse gases every year. In Victoria alone, this translates to approximately one million tonnes of greenhouse gases annually.

"On a global scale, they produce roughly 700 million tonnes of greenhouse gases every year," he said. "Now we think about Victoria alone, for example, that is roughly one million tonnes of greenhouse gases every year."

Future trials and applications

The researchers are now trialling similar floating wetlands in farm dams across the Bass Coast, investigating their potential to improve water quality, biodiversity, and emissions. Dr. Schuster said water companies had already expressed interest in further trials.

"It's also not only emission reduction, but also pollutant removal," he said. "We're talking about perfluoroalkyl and polyfluoroalkyl substances (PFAS) removal or other pollutants in the wastewater and also maybe provide habitat for biodiversity."

Kernot farmer Camilla Graves has floating wetlands in two of her 26 farm dams as part of the trial. She said the technology could be easily adopted by other farmers, highlighting its simplicity and potential for widespread implementation.

"The floating wetlands have actually provided an opportunity for them to take some shelter where the foxes can't get to them because the floating wetland literally is in the middle of the dam," Ms Graves said.