Constructed WetlandsAshley Buffington
http://www.gocolumbiamo.com/PublicWorks/Sewer/wwtppg_4.php
Constructed WetlandsCreated 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 systemsZero discharge systems
Constructed Wetlands:Free-Water Surface FlowBasins 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 macrophytesFloating-leaved macrophytesSubmerged macrophytesEmergent macrophytes
http://sudied.blogspot.com/2010/04/water-and-city.html
Constructed Wetlands:Sub-Surface FlowContain underground flow
of wastewater through substrate
Can be beneficial in areas where wildlife is discouraged
Types of SSF CWs:Horizontal Flow (HF)Vertical Flow (VF)
Down flow Up flow
http://sudied.blogspot.com/2010/04/water-and-city.html
http://sudied.blogspot.com/2010/04/water-and-city.html
Constructed Wetlands:Hybrid SystemsResult 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 SystemsDeveloped 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 regularlyhttp://www.pilerensning.dk/english/index.php?option=com_content&view=article&id=53&Itemid=56&lang=da
Constructed Wetlands:AdvantagesCost 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:LimitationsRequire 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
Where is the capital cost of wetland construction per unit area ($ and is the wetland area (ha)
1-ha wetland ≈ $200,00010-ha wetland ≈ $60,000 per ha100-ha wetland≈ $19,000 per ha
SSF CWs are more expensive than FWS CWsInitial cost ≈ $388,000 (SSF); ≈ $58,000 (FWS)
Constructed Wetlands:Operation and MaintenanceLife expectancy between 30-50 years
General maintenance tasks:Removing debris/litterMonitoring depth of sedimentsChecking for channelizationIdentifying any damage from vandalismInspecting inlet and outlet
Operation and maintenance cost ≈ $85,000 annuallyEstimated for a 175 ha wetlandIncludes approx. $50,000 for personnelCosts range from $5,000-$50,000 for smaller wetlands
Case Study:Apache Powder Superfund SiteCochise 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:Apache Powder Superfund SiteCochise County, Arizona
Multi-celled wetland system used
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.
Questions
?