Floating wetlands

The gradual increase in the concentration of nitrogen, phosphorous, and other plant nutrients in an aquatic ecosystem is referred to as eutrophication. This process is typically characterised by excessive growth of algae or plankton in a water body and is a major environmental concern because it can eventually lead to a decrease in dissolved oxygen in the affected water body as well as a deterioration of water quality. This is particularly problematic in a country such as South Africa, where the freshwater sources are already limited.

Wetlands and their aquatic plant habitats play a significant role in water quality improvement. Wetlands, both natural and man-made have been frequently employed to improve water quality. Floating wetlands are ecosystems created by using a buoyant substrate to support plants and allow them to grow hydroponically, with their roots dangling down into the water column. Plants, as the primary engine of the ecosystem, alter the pH, temperature, and dissolved oxygen of the water column, removing nutrients and heavy metals from the water column through root uptake, thereby preventing eutrophication.

Floating wetlands are being seen as an effective ecological engineering option for removing nutrients from water sources. In recent years, this ‘phyto-technology,’ in which macrophytes grow on a buoyant platform and absorb nutrients like phosphorus and nitrogen directly from the water, has gained popularity. Harvesting above ground biomass can directly remove absorbed nutrients from the system.

Furthermore, these floating wetlands create just enough shade in the water, influencing the temperature and availability of sunlight for algae development. Floating wetlands are also known to provide other ecosystem services such as habitat provision. They provide a haven for aquatic animals and alternative breeding grounds for birds.

Floating wetlands are an eco-friendly and natural way to prevent algal growth in surface water systems. These buoyant filtration systems are ideal for use in built-up urban environments, as they encourage local birds and insects, as well as provide a pleasant landscape. They can also reduce pollution in stormwater run-off.

Conserving and enhancing natural habitats and environments, especially in urban areas, is essential to protect the functioning of the ecosystems that provide us with crucial goods and services, such as clean water. Utilising floating wetlands to remove pollutants from collected and stored water is a great way to look after our most precious natural resource.

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