Constructed Wetlands

Report
Ashley Buffington
http://www.gocolumbiamo.com/PublicWorks/Sewer/wwtppg_4.php
Constructed Wetlands
 Created to treat variety of wastewaters
 First experiments carried out by Käthe Siedel in
Germany in 1952
 Classified into four categories:
 Free-water surface flow (FWS)
 Sub-surface flow (SSF)
 Hybrid systems
 Zero discharge systems
Constructed Wetlands:
Free-Water Surface Flow
 Basins with shallow waters and substrate to support
rooted vegetation
 First FWS CW created in Ijssel Lake Polder Authority in
Flevoland in the Netherlands in 1967
 FWS CW systems with:
 Free-floating macrophytes
 Floating-leaved macrophytes
 Submerged macrophytes
 Emergent macrophytes
http://sudied.blogspot.com/2010/04/water-and-city.html
Constructed Wetlands:
Sub-Surface Flow
 Contain underground flow of
wastewater through substrate
 Can be beneficial in areas where
wildlife is discouraged
http://sudied.blogspot.com/2010/04/water-and-city.html
 Types of SSF CWs:
 Horizontal Flow (HF)
 Vertical Flow (VF)


Down flow
Up flow
http://sudied.blogspot.com/2010/04/water-and-city.html
Constructed Wetlands:
Hybrid Systems
 Result from combining
different types of CWs
 Advantages and
disadvantages of CWs
combined to
complement each other
 Higher treatment effect
accomplished
http://www.iridra.com/eng/cw_ibr.htm
Constructed Wetlands:
Zero-discharge Systems
 Developed in Denmark for
sewage disposal in rural
areas
 Consists of basins lined
with HDPE, filled with soil
and planted with willows
 Removal of water via
evapotranspiration
 Harvested regularly
http://www.pilerensning.dk/english/index.php?option=com_content&view=article&id=53&Itemid=56&lang=da
Constructed Wetlands:
Advantages
 Cost 50-90% less than conventional wastewater treatment
systems
 Require little external energy input
 Rely on solar energy to operate
 More sustainable compared to conventional treatment plants
 Improve air quality and help fight global warming
 Provide green space, habitat for wildlife, recreational and
educational opportunities
Constructed Wetlands:
Limitations
 Require large areas of land
 Require long periods for vegetation to establish for optimal
treatment efficiencies
 Potentially susceptible to influences such as storms, wind,
and floods
 Steep topography and high water table limit these systems
 Expensive to implement
Constructed Wetlands:
Costs
 CA = $196,336A−0.511
 Where CA is the capital cost of wetland construction
per unit area ($ha−1 ) and A is the wetland area (ha)
 1-ha wetland ≈ $200,000
 10-ha wetland ≈ $60,000 per ha
 100-ha wetland≈ $19,000 per ha
 SSF CWs are more expensive than FWS CWs
 Initial cost ≈ $388,000 (SSF); ≈ $58,000 (FWS)
Constructed Wetlands:
Operation and Maintenance
 Life expectancy between 30-50 years
 General maintenance tasks:
 Removing debris/litter
 Monitoring depth of sediments
 Checking for channelization
 Identifying any damage from vandalism
 Inspecting inlet and outlet
 Operation and maintenance cost ≈ $85,000 annually
 Estimated for a 175 ha wetland
 Includes approx. $50,000 for personnel
 Costs range from $5,000-$50,000 for smaller wetlands
Case Study:
Apache Powder Superfund Site
Cochise County, Arizona
 Approx. 9 mi² and 1,100 acres owned
by Apache Nitrogen Products (ANP)
 Began manufacturing industrial
chemicals and explosives in 1922
 Produced liquid and solid wastes
disposed on ANP property
 Investigated in 1987
 Soils showed high levels of heavy
metals and arsenic
 Groundwater showed high levels of
contamination as well
Case Study:
 Multi-celled wetland system used
Apache Powder Superfund Site 
Cochise County, Arizona
Groundwater pumped from shallow
aquifer to first cell
 Nitrate levels in groundwater
entering first cell were approx. 250
ppm
 Nitrate levels leaving fifth cell were
approx. 10 ppm
 Can treat 200 gallons water per
minute
 Water stays about 5 days in system
 Costs savings estimated to be $15
million
References

Federico, R., and J. Kandasamy. "Operation and Maintenance of Wetlands." Constructed Wetlands. Ed. Jaya Kandasamy and
Saravanamuthu Vigneswaran. New York: Nova Science, 2008. 57-73. Print.

Ghanem, P. and B. Simpson. "Design and Construction of Constructed Wetlands." Constructed Wetlands. Ed. Jaya Kandasamy
and Saravanamuthu Vigneswaran. New York: Nova Science, 2008. 27-56. Print.

Lorion, Renee. "Constructed Wetlands: Passive Systems for Wastewater Treatment." U.S. Environmental Protection Agency,
Aug. 2001. Web. 20 Mar. 2011.
<http://permanent.access.gpo.gov/websites/epagov/www.epa.gov/swertio1/download/remed/constructed_wetlands.pdf>.

Mitsch, William J., and James G. Gosselink. Wetlands. 4th ed. Hoboken, NJ: Wiley, 2007. Print.

Moat, G., B. Simpson, P. Ghanem, J. Kandasamy, and S. Vigneswaran. "Constructed Wetlands: Classification, Functions, and
Treatment." Constructed Wetlands. Ed. Jaya Kandasamy and Saravanamuthu Vigneswaran. New York: Nova Science, 2008. 1-26.
Print.

"Region 9: Superfund." Environmental Protection Agency, 14 July 2010. Web. 19 Apr. 2011.
<http://yosemite.epa.gov/r9/sfund/r9sfdocw.nsf/vwsoalphabetic/Apache+Powder+Company?OpenDocument>

Vymazal, Jan, and Lenka Kröpfelová. Wastewater Treatment in Constructed Wetlands with Horizontal Sub-surface Flow. Berlin:
Springer Netherland, 2008. Print.

Vymazal, Jan, Margaret Greenway, Karin Tonderski, Hans Brix, and Ulo Mander. "Constructed Wetlands for Wastewater
Treatment." Wetlands and Natural Resource Management. Ed. J. T. A. Verhoeven, B. Beltman, R. Bobblink, and D. F. Whigman.
Vol. 190. Berlin: Springer, 2006. 69-96. Print. Ecological Studies.
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