Do you know what a floating treatment wetland (FTW) is? If you were at the 2024 SAW Annual Conference, you may remember a presentation by Dr. Richard Grosshans from the International Institute for Sustainable Development (IISD). Dr. Grosshans discussed the application of FTWs for improvement of water quality of ponds in urban areas.
Floating treatment wetlands are artificial platforms that contain aquatic emergent plants. These platforms allow the plants to grow in water that is typically too deep. The roots spread down through the platform and into the water creating columns of roots that are dense and therefore have a lot of surface area. The plants take up nutrients and contaminants and provide a surface area for important microbes to grow. The microbes form a biofilm layer that filters the water. Another benefit that comes from having floating wetlands, is that they reduce turbulence caused by waves, therefore allowing sediment to settle.
Urban planning generally includes systems to hold storm water, wastewater, or flood waters. These systems are created simply to catch and hold water and contain nutrients and pollutants that are harmful to our water and environment. By creating floating wetlands, you add the potential of capturing the nutrients and pollutants preventing them from entering streams, rivers, and lakes.
There are also additional benefits to FTWs. These platforms add to habitat above and below the water’s surface. Below the surface, communities of fish, algae, bacteria, fungi, insects, and protozoans can thrive. Above the surface, birds and pollinators will benefit from the FTWs.
Today, FTWs are being integrated into urban planning more and more, and are used throughout North America and the world. For example, in 2019, the City of Saskatoon worked with the South Saskatchewan River Watershed Stewards (SSRWS) to incorporate an FTW into the Evergreen storm pond at the Northeast Swale. As research and development continues, the benefits and construction of FTWs will grow. Dr. Grosshan’s presentation is available to view through the SAW Website.
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