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'''A Free-Water Surface Constructed Wetland is a series of flooded channels that aims to replicate the naturally occurring processes of a natural wetland,marsh or swamp. As water slowly flows through the wetland, particles settle, pathogens are destroyed, and organisms and plants utilize the nutrients.'''
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===Adequacy===
Free-Water Surface Constructed Wetlands can achieve high removals of suspended solids and moderate removal of pathogens, nutrients and other pollutants such as heavy metals. Shade from plants and protection from wind mixing limit the dissolved oxygen in the water, therefore, this technology is only appropriate for low strength wastewater. Usually this requires that Free-Water Surface Constructed Wetlands are only appropriate when they follow some type of primary treatment to lower the BOD.
This technology is best suited to warm climates but can be designed to tolerate some freezing and periods of low biological activity.
===Health Aspects/Acceptance===
The open surface can act as a potential breeding ground for mosquitoes. However, good design and maintenance can prevent this.
The Free-Water Surface Constructed Wetlands are generally aesthetically pleasing, especially when they are integrated into pre-existing natural areas. Care should be taken to prevent people from coming in contact with the effluent because of the potential for disease transmission and the risk of drowning in deeper waters.
===Maintenance===
Regular maintenance should ensure that water is not short-circuiting, or backing up because of fallen branches, garbage, or beaver dams blocking the wetland outlet. Vegetation may have to be cut back or thinned out periodically.
===References===
* Crites, R. and Tchobanoglous, G. (1998). Small and Decentralized Wastewater Management Systems. WCB and McGraw-Hill, New York, USA. pp 582–599. (Comprehensive summary chapter including solved problems.)
* General information [http://www.constructedwetlands.org www.constructedwetlands.org ]
===Acknowledgements===
{{:Acknowledgements Sanitation}}