Designed ecosystems are typified by human-made environments consisting of constructed wetlands, soil filters, and various combinations of these. These are relatively low-tech systems which mimic natural environments to treat wastewater from both households and industries. Designed ecosystems can remove a wide range of potential pollutants with processes similar or identical to mechanically sophisticated systems, but using simpler components. Because they are based on soil and plants rather than concrete and metal, they can potentially treat wastewater with low costs and low maintenance.
Both systems — constructed wetlands and soil filters — have been used independently for some time. But by combining them into hybrid systems, scientists can build on the advantages that one system has over another in removing the nutrients and other unwanted materials that become pollutants when released into the environment. Together, the range of treatment is extended (House, C. H., D. J. Frederick, S. W. Broome, and A. R. Rubin. 1996.) and the size and cost are often reduced.
Excerpted from Waterwise, Winter 1995