Floating Wetlands Cut Wastewater Emissions by 30%

A tennis court-sized floating garden just proved it can fight climate change while cleaning dirty water.

Researchers in Victoria, Australia, placed a 330-square-metre platform of native reeds and sedges on a wastewater lagoon at Phillip Island. Over two years, the floating wetland cut the lagoon's greenhouse gas emissions by about 30% compared to a control lagoon without plants.

The results were even more impressive when you look at individual gases. Carbon dioxide emissions dropped by up to 36%, methane plummeted by 66%, and nitrogen decreased by 18%.

Dr. Lukas Schuster from RMIT University's Centre for Nature Positive Solutions explained how it works. The plants' roots hang down into the wastewater below, creating habitat for helpful microbes that break down organic matter and absorb pollutants.

The trial marks the first time researchers have tested floating wetlands at this scale in a real-world wastewater treatment setting. Solar-powered sensors monitored emissions continuously for two years from the lagoon, which held 14 million litres of wastewater.

The Ripple Effect

This innovation arrives at the perfect time. Wastewater treatment produces roughly 700 million tonnes of greenhouse gases globally each year. In Victoria alone, that's about one million tonnes annually.

What makes this solution special is its simplicity. Water companies can retrofit floating wetlands into existing lagoons without major infrastructure overhauls. Several water utilities have already expressed interest in running their own trials.

The benefits extend beyond emissions reduction. The floating wetlands also remove pollutants like PFAS from wastewater and create habitat for local wildlife.

Researchers are now testing similar platforms in farm dams across the Bass Coast region. Kernot farmer Camilla Graves has two floating wetlands in her 26 farm dams and loves the results.

"Water quality is really prime to agriculture," Graves said. She's also noticed an unexpected benefit: ducks use the floating platforms as shelter from foxes since the wetlands sit in the middle of the dams.

The research team is working to make future platforms more sustainable by using recycled or plant-based materials instead of plastic baskets. They're also exploring how floating wetlands might improve water quality and support biodiversity in different environments.

Graves believes other farmers will embrace the technology because of its straightforward design. "Its simplicity is amazing; this concept can definitely be rolled out Australia-wide to farmers that are interested in giving it a go," she said.

A simple floating garden is proving that nature-based solutions can deliver measurable climate wins while making our water cleaner and our ecosystems healthier.