Artificial wetlands: a remarkable natural filter

Almost all sewage works in South Africa return nutrient rich (“polluted”) water back into natural ecosystems, creating eutrophic conditions in rivers and estuaries. Gouritz Cluster Biosphere Reserve has developped a programme to increase water supply and improve water quality for community agricultural use by reconstructing an artificial/constructed wetland.

Artificial (or constructed) wetlands are remarkable natural filters that remove nutrients from waste water. These floating constructed wetlands (see pictures) form part of the waste water treatment process. in De Rust, South Africa.

As the roots of the aquatic plants (mostly Phragmites australis) grow out and down towards the sediment, they form a filter, absorbing nutrients (like ammonium and phosphates). The cleaner water can then be returned to the natural stream, or be used for micro-farming by the local community.