Floating Wetlands: A Cleaning Solution for Polluted Farm Dams

Floating wetlands are successful at improving the quality of nutrient-polluted water, and can be made from a few basic materials, says Dr Alanna Rebelo, a senior researcher in the Department of Conservation Ecology and Entomology at Stellenbosch University.

- By Dr Alanna Rebelo

Wetland plants indigenous to South Africa can remove excess nutrients from farm dams and assist in the purification of the water. SEAN ALTERN

The availability of usable fresh water is one of the main limiting factors to South African agriculture; the country experiences large annual and in-season variability in its supply of fresh water.

Farm dams are therefore an essential source of water for agricultural activities, as they bridge the gap between low- and high-flow periods by providing an efficient means for storing water.

Unfortunately, farm dams are prone to nutrient pollution, resulting in poor water quality. Increased nutrient levels lead to excessive algal growth, which can, in turn, result in the emission of harmful toxins. Furthermore, algal growth can cause major problems in farm dams by blocking irrigation systems.

This reduces the ability of these dams to provide safe, usable water for irrigation, as well as human and livestock consumption.

ENTER FLOATING WETLANDS

Floating wetlands are a budget-friendly and nature-based solution for improving water quality and increasing biodiversity. They comprise buoyant structures on which wetland plants are grown, and they use natural processes to remove nutrients and other agricultural chemicals from the water.

Plants require certain nutrients, especially nitrogen (N) and phosphorus (P), for growth. Under normal circumstances, they would obtain said nutrients from the soil through their roots.