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Constructed wetlands are planned systems designed and constructed to employ wetland vegetation to assist in treating wastewater in a more controlled environment than occurs in natural wetlands. As presented in a recent US EPA report, this chapter reviews the extent and circumstances of this practice and summarizes the regulatory issues and EPA policies involved. Under appropriate conditions, both natural and constructed treatment systems have achieved high removal efficiencies for BOD5 , SS, nutrients, heavy metals, trace organic compounds, and pathogens from municipal wastewater. However, rather than a single concept of wetland wastewater treatment, a number of approaches combine wastewater and wetlands as a part of water quality management projects. These include natural wetlands for wastewater disposal; wetland enhancement, restoration, or creation; natural wetlands for wastewater treatment or reclamation; and constructed wetlands for wastewater treatment. Currently, use of constructed rather than natural wetlands is generally preferred by EPA when projects for wastewater treatment are proposed. |
