Artificial floating wetlands are emerging as a cost-effective and natural solution for water pollution, according to new research by Australian scientists. The study, published by researchers from the University of South Australia and the CSIRO, examined 11 floating wetlands worldwide and found they can remove nutrients like nitrogen and phosphorus at a competitive cost compared to traditional engineering methods.
“We’ve worked out that no matter how hard you engineer something, nature filters everything much better than anything else,” said Prof Simon Beecham from the University of South Australia, a co-author of the study. The wetlands consist of buoyant plastic pods planted with fast-growing reeds, whose roots develop a biofilm that absorbs and breaks down pollutants.
In Queensland, a floating wetland has been deployed at the Sunshine Coast Council’s resource recovery centre to treat runoff from garden clippings. Environmental engineer Chris Walker, also a co-author, explained that the plants capture nutrients that would otherwise pollute nearby bushland. “We’re dealing with heavy pollutants and they come with significant maintenance needs,” he said.
The study, led by Dr John Awad from the CSIRO, found that larger wetlands are more cost-effective per kilogram of nutrient removed. Climate also plays a role, with warmer regions achieving higher removal rates due to longer growing seasons. “Floating wetlands mimic the functions of natural ecosystems, filtering nutrients and pollutants through plant roots and microbial communities,” Dr Awad said.
Examples of floating wetlands in use include a 4,000 sq metre installation in Florida to treat pesticides, a project on the Chicago River for habitat restoration, and applications in Pakistan for cleaning crude oil wastewater and in Canada for domestic wastewater treatment. The researchers say the technology is particularly valuable for low- and middle-income countries needing affordable, low-energy treatment systems.
