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Constructed Wetlands Treatment of Municipal Wastewaters (166 pp, 1.6 MB) September 2000
Constructed wetlands are man-made wastewater treatment systems. They usually have one or more cells less than 1 meter deep and are planted with aquatic greenery. Water outlet structures control the flow of wastewater through the system to keep detention times and water levels at the desired level. Constructed wetlands are used for many purposes: polishing conventionally treated wastewater, holding and treating storm water, treating industrial or agricultural wastewater, and treating acid mine drainage and landfill leachates. The new USEPA manual is entitled, "Constructed Wetlands Treatment of Municipal Wastewaters." The scope will be limited to constructed wetlands designed and built as the major unit process in a system to treat municipal wastewater. Wastewater always requires some pre-treatment and different types of post-treatment to meet most stream discharge or reuse requirements, but the wetland comprises the major treatment component. This manual discusses the capabilities of treatment constructed wetlands, a functional design approach, and the management requirements to achieve their designed purpose. The manual also attempts to put the proper perspective on the appropriate use, design and performance of constructed wetlands. For some applications, they are an excellent option because they are low in cost and in maintenance requirements, offer good performance, and provide a natural appearance, and ecological benefits. In other applications, such as large urban areas with large wastewater flows, they are not at all appropriate owing to their land requirements and mosquito-breeding potential. Constructed wetlands are especially well suited for wastewater treatment in small communities where inexpensive land is available and skilled operators hard to find and keep.