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.

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