1. Constructed Wetlands Ashley Buffington

2. 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
Domestic, industrial, and agricultural wastewaters, stormwater, mine drainage, landfill leachate, and runoff
First experiments using wetland vegetation for wastewater treatment were carried out by Kathe Siedel at the Max Planck Institute in Plon, Germany in 1952

3. 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

4. Constructed Wetlands: Sub-Surface Flow
Contain 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

5. 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
VF + HF: vertical subsurface system leads to horizontal subsurface system> aims toward more efficient de-nitrification
HF + VF: horizontal subsurface, then vertical subsurface; H SSF removes most organic and suspended solids; V SSF > high oxidation and efficient nitrification
HF +VF +HF +FWS: achieves de-nitrification through last HF, FWS removes nitrogen components and accomplishes microbial load

6. 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
Use for individual households
Evapotranspiration: Soil and plant surfaces
1/3 willows harvested yearly to keep stock young and healthy. encourages high transpiration rates, and removes some nutrients and heavy metals

7. 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

8. 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
(2-3) growing seasons

9. Constructed Wetlands: Costs
C A = $196,336 A −0.511
Where C A is the capital cost of wetland construction per unit area ($ 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)

10. Constructed Wetlands: Operation and Maintenance
Life expectancy between 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
If rehabilitated every 10 years

11. 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
Including nitroglycerin, nitric acid, ammonium nitrates, blasting agents, and liquid and solid-based fertilizers; Primary production was nitroglycerin
Through a drain into unlined ditches
Soil: Some Contaminants of concern included: barium, beryllium, chromium, lead, manganese and nitrate
Groundwater. Perched water table as well as shallow groundwater aquifer contaminated: COC included: arsenic, fluoride, nitrate (perched) and nitrate and perchlorate in aquifer
Residents used shallow groundwater aquifer as source of drinking water. Sampling detected 470mg/l nitrate in one drinking well on the site.

12. Case Study: Apache Powder Superfund Site Cochise 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
Case Study: Apache Powder Superfund Site Cochise County, Arizona
Consists of 5 cells: first 3 are planted with emergent plants, fourth cell is planted with submerged, and the fifth is a polishing cell
Nitrate levels consistently reduced to less than 10ppm

13. References
Federico, R., and J. Kandasamy. "Operation and Maintenance of Wetlands." Constructed Wetlands. Ed. Jaya Kandasamy and Saravanamuthu Vigneswaran. New York: Nova Science, Print.
Ghanem, P. and B. Simpson. "Design and Construction of Constructed Wetlands." Constructed Wetlands. Ed. Jaya Kandasamy and Saravanamuthu Vigneswaran. New York: Nova Science, Print.
Lorion, Renee. "Constructed Wetlands: Passive Systems for Wastewater Treatment." U.S. Environmental Protection Agency, Aug Web. 20 Mar <
Mitsch, William J., and James G. Gosselink. Wetlands. 4th ed. Hoboken, NJ: Wiley, 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, Print.
"Region 9: Superfund." Environmental Protection Agency, 14 July Web. 19 Apr <
Vymazal, Jan, and Lenka Kröpfelová. Wastewater Treatment in Constructed Wetlands with Horizontal Sub-surface Flow. Berlin: Springer Netherland, 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 Berlin: Springer, Print. Ecological Studies.

14. Questions ?