Constructed Wetlands
Constructed wetlands, as the name implies, are treatment systems that simulate the ecological water purification techniques of natural wetlands and use plants, soils, and microorganisms to remove contaminants. These constructed wetlands serve an auxiliary role in the treatment of municipal wastewater and drinking water. There are two main types of constructed wetlands: free water surface and vegetated submerged bed (EPA, 1993).
Free Water Surface (FWS)
· Resemble natural wetlands with areas of both open water and full of vegetation
· Combine emergent aquatic plants (cattail, bulrush, reeds), floating plants (duckweed, water hyacinth), and submerged plants (sago pondweed, widgeon grass)
Free Water Surface (FWS)
· Resemble natural wetlands with areas of both open water and full of vegetation
· Combine emergent aquatic plants (cattail, bulrush, reeds), floating plants (duckweed, water hyacinth), and submerged plants (sago pondweed, widgeon grass)
Vegetated submerged bed (VSB)
· Gravel beds planted with wetland vegetation
· Consist of ‘subsurface flow wetland’ where the upper layer of water is static
· The water flow starts below ground
· No hydric soils (technically not a wetland)
· Emergent plants root into the gravel, with water traveling through the gravel rather than across the surface
· Gravel beds planted with wetland vegetation
· Consist of ‘subsurface flow wetland’ where the upper layer of water is static
· The water flow starts below ground
· No hydric soils (technically not a wetland)
· Emergent plants root into the gravel, with water traveling through the gravel rather than across the surface
Similarity to Natural Wetlands
· Both FWS and VSB wetlands are based on the ecological, chemical, and biological processes found in natural wetlands.
Differences from Natural Wetlands
· In constructed wetlands, there is a stable flow of water, which is not as variable as it would be in nature
· The amount of suspended solids and levels of other contaminants are higher than they would be in nature.
· Both FWS and VSB wetlands are based on the ecological, chemical, and biological processes found in natural wetlands.
Differences from Natural Wetlands
· In constructed wetlands, there is a stable flow of water, which is not as variable as it would be in nature
· The amount of suspended solids and levels of other contaminants are higher than they would be in nature.
Brief Youtube video about a constructed wetland in Acata, CA