The world's first large-scale trial of floating wetlands at a wastewater treatment plant has been conducted. On Phillip Island in Victoria, Australia, a platform with native plants was installed in a wastewater lagoon.
The two-year experiment was conducted by researchers from RMIT University in collaboration with Westernport Water and CSIRO. The platform, measuring approximately 330 square meters—about the size of one and a half tennis courts—was filled with reeds and sedges.
The plant roots hung down into the water, creating an environment for microbes. It was these microbes, rather than nutrient removal, that proved to be the key to reducing emissions.
The results showed that total greenhouse gas emissions were reduced by approximately 30 percent compared to the control lagoon. CO₂ emissions dropped by up to 36 percent, and methane by up to 66 percent.
The reduction occurred as early as four to seven months after installation. Nitrogen levels also decreased by 18 percent.
Wastewater makes a significant contribution to global methane and nitrous oxide emissions. Here, nature has offered a simple solution without complex technology.
Can such an approach be scaled to other regions and types of water bodies? Researchers are already testing the design on farm ponds in the Bass Coast area.
Floating wetlands fit easily into existing lagoons. This paves the way for the decarbonization of the water sector using nature-based solutions.
The project supports Victoria's goals of achieving carbon neutrality by 2035. Further trials will show how widely the method can be applied.
