As the plants are pulled out of one of the cells of their floating pod, the long and thin roots are covered with slime.<\/p>\n
\u201cThis is what you want,\u201d says Chris Walker, an environmental engineer who is struggling to keep hold of the weight of the clump of reeds.<\/p>\n
\u201cIt\u2019s biofilm and it\u2019s taking up all those nutrients and breaking them up.\u201d<\/p>\n
A steady stream of utility vehicles and trailers comes in and out of the Sunshine Coast council\u2019s resource recovery centre in Caloundra, dropping off piles of garden clippings and soil that are pushed by a dumper truck into a tiny mountain which, given time, will turn into compost.<\/p>\n
Walker is in Queensland<\/a> with Prof Simon Beecham from the University of South Australia to inspect an artificial floating wetland that\u2019s been deployed in a pond to help soak up the floods of nitrogen and phosphorus that run from all those garden clippings after rain falls.<\/p>\n The artificial floating wetland installed in Caloundra Photograph: David Kelly\/The Guardian<\/p>\n \u201cWe\u2019re dealing with heavy pollutants and they come with significant maintenance needs,\u201d says Walker, who works for engineering consultants Covey. \u201cWe don\u2019t want it going in there,\u201d he adds, pointing to bushland just over the bank of the pond.<\/p>\n The council, with Walker\u2019s help, has deployed a small artificial floating wetland to the pond \u2013 a buoyant jigsaw of heavy-duty plastic pods with fast-growing reeds planted in the holes. The plants are doing the work of extra chemicals and other engineering to grab and lock up the nutrients in water, stopping it from going putrid.<\/p>\n It\u2019s just one example of an artificial floating wetland that are being increasingly used around the world in rivers, lagoons and wastewater treatment ponds to clean up water \u2013 and in some cases, bring new habitats for wildlife.<\/p>\n Artificial floating wetlands in the Chicago river, in the middle of the city. Photograph: Dave Burk<\/p>\n In Florida, an almost 4,000 sq metre floating wetland is being used to help take pesticides and nutrients out of a recreation area<\/a> and stop them entering a lagoon.<\/p>\n In the middle of Chicago, an industrial stretch of the city\u2019s Chicago river is being transformed with floating wetlands with boardwalks attached; elsewhere on the river floating plant beds<\/a> are cleaning up a creek and providing habitat for birds and aquatic mammals.<\/p>\n In Pakistan, floating wetlands have been deployed to clean up a crude oil wastewater pit<\/a>; while in Canada, they\u2019re being used to treat domestic wastewater<\/a>.<\/p>\n \u201cWe have always been taught that solutions need hard engineering \u2013 you had a system and you add a process and some chemicals,\u201d says Beecham.<\/p>\n \u201cBut we\u2019ve worked out that no matter how hard you engineer something, nature filters everything much better than anything else. Engineers are working out that nature does a pretty good job by itself. If you can use nature, you\u2019ll come out with a more optimal answer.\u201d<\/p>\n Beecham and Walker are co-authors of new research documenting the economics of floating wetlands around the world<\/a>, finding they were a cost-effective way to improve water quality.<\/p>\n skip past newsletter promotion<\/a><\/p>\n Sign up to Clear Air Australia<\/p>\n Adam Morton brings you incisive analysis about the politics and impact of the climate crisis<\/p>\n Privacy Notice: Newsletters may contain information about charities, online ads, and content funded by outside parties. If you do not have an account, we will create a guest account for you on theguardian.com<\/a> to send you this newsletter. You can complete full registration at any time. For more information about how we use your data see our Privacy Policy<\/a>. We use Google reCaptcha to protect our website and the Google Privacy Policy<\/a> and Terms of Service<\/a> apply.<\/p>\n after newsletter promotion<\/p>\n The wetlands vary in style and application: some combine natural materials to make the floating platforms that will need replacing every few years; others can last 20 years or more.<\/p>\n \u201cWhat\u2019s been missing is the economics of it,\u201d says Walker.<\/p>\n