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Regional Waste Management Department, 400 West Summit Hill Drive, OCH 2 B, Knoxville, TN 37902

Natural wetland ecosystems provide many functional values. Most can be lumped into three board categories: life support, hydrologic buffering, and water purification. Although overlooked until fairly recently, the water purification function may be the most significant functional value for human societies and the biosphere. Wetlands accomplish water quality improvement through a number of physical, chemical, and biological processes operating independently in some circumstances and interacting in others. Studies of natural wetlands have provided guidance for use of constructed wetlands for treating a variety of wastewaters.

Constructed wetlands treat wastewaters from towns and small cities, mine drainage, urban stormwater runoff, livestock producers, failed septic tank drain fields, land fill leachate, pulp-paper mills, tanneries, food processing plants, petroleum refineries, and many other small industrial sources on every continent except Antarctica. Constructed wetlands can provide low-cost, efficient treatment to high discharge standards for wastewater flows of >7.5 million liters/day, but only proper design and construction will ensure correct functioning and low operating costs.