Improving Performance of Treatment Wetlands: Evaluation of Supplemental Aeration,Varying Flow Direction,and Phosphorus Removing Filters |
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| Authors: | Saalem Adera Aleksandra Drizo Eamon Twohig Keshav Jagannathan Gaboury Benoit |
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| Institution: | 1.School of Forestry and Environmental Studies,Yale University,New Haven,USA;2.Geography Department,University of California-Berkeley,Berkeley,USA;3.Department of Plant and Soil Science,University of Vermont,Burlington,USA;4.Water and Soil Solutions International Ltd.,Edinburgh,UK;5.Vermont Department of Environmental Conservation,Montpelier,USA;6.Department of Mathematics and Statistics,Coastal Carolina University,Conway,USA |
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| Abstract: | Pollutant removal was compared among subsurface flow constructed wetland (CW) mesocosms used for dairy farm wastewater treatment. Supplemental aeration, flow direction, and the use of phosphorus-reducing filters (PRFs) were varied among the CWs. The following were compared: (1) vertical flow CWs with and without supplemental aeration, (2) aerated CWs with horizontal and vertical flow directions, (3) single-cell and two-cell treatment systems, and (4) wetland-wetland systems (two CWs in series) and wetland-PRF systems (a CW followed by a PRF). The results from this investigation showed that, first, nearly all treatment strategies, either singly or in pairs, substantially reduced almost all the contaminants we tested. Second, supplemental aeration resulted in higher ammonium-nitrogen (NH4-N) removal efficiencies in aerated vertical flow CWs, compared to unaerated CWs. However, it caused no further improvement in dissolved reactive phosphorus (DRP), total suspended solids (TSS), E. coli, or BOD5 removal. Third, there was no difference between aerated horizontal and aerated vertical flow CWs in removal of any of the tested contaminants. Fourth, adding a second stage of treatment significantly improved DRP, TSS, E. coli, and NH4-N removal, but not BOD5. Finally, treatment systems with PRFs showed superior performance in DRP and E. coli removal. |
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