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[[Image:Icon_horizontal_subsurface_flow_constructed_wetland.png |right|95px]]
'''A Horizontal Subsurface Flow Constructed Wetland is a large gravel and sand-filled channel that is planted with aquatic vegetation. As wastewater flows horizontally through the channel, the filtermaterial filters out particles and microorganisms degrade organics.'''
With time, the gravel will clog with accumulated solids and bacterial film. The filter material will require replacement every 8 to 15 or more years. Maintenance activities should focus on ensuring that primary treatment is effective at reducing the concentration of solids in the wastewater before it enters the wetland. Maintenance should also ensure that trees do not grow in the area as the roots can harm the liner.
==Acknowledgements=={{:Acknowledgements Sanitation}} ==References and external links==
* Crites, R. and Tchobanoglous, G. (1998). Small and Decentralized Wastewater Management Systems. WCB and McGraw-Hill, New York, USA. pp 599–609. (Comprehensive summary chapter including solved problems.)
* Reed, SC. (1993). Subsurface Flow Constructed Wetlands For Wastewater Treatment, A Technology Assessment. United States Environmental Protection Agency, USA. Available: http://www.epa.gov (Comprehensive design manual.)
==Acknowledgements==
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