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Published literature has indicated that when properly designed and maintained, constructed wetlands provide predictable water-quality improvement. However, because of the complexity or heterogeneity of wastewaters and the lack of quality data (both temporal and spatial) currently available from full-scale constructed wetland treatment systems, many constructed wetland designs fail to provide predictable water-quality improvement. By understanding internal thermodynamic processes and design criteria that affect the removal of targeted constituents in constructed wetlands, constructed wetland technology can be accurately and reliably transferred from site to site. Specific design parameters that should be identified when designing a constructed wetland include (1) character of the wastewater including the targeted constituents, (2) performance goals or desired levels of treatment, (3) transfer and transformation pathways, (4) flow rates and retention time required to achieve treatment, and (5) climate (i.e., temperature and precipitation). Using these guidelines, this research evaluated the performance of a constructed wetland treatment system for treatment of a copper-contaminated wastewater. Specifically, this system was designed to achieve a regulatory limit of ≤22 μg/L total recoverable copper and eliminate toxicity in a waste stream by coupling the copper, sulfur, and carbon cycles, so that copper will be precipitated from the water column and sequestered in the sediment in nonbioavailable forms. In this constructed wetland treatment system, average acid-soluble copper concentrations decreased by 85%, and soluble copper decreased by 83% from upstream of the system to downstream, and the toxicity associated with the bioavailable fraction of copper was effectively removed.
Cynthia Murray-Gulde is currently an adjunct professor of both Departments of Forestry and Natural Resources and Engineering and Science at Clemson University. She obtained her B.S. degree in wildlife and fisheries in 1993 and her M.S. degree in environmental science in 1997. She has published a number of articles, and has presented various works in conferences both in oral and poster presentations. She is currently a member of the Society of Environmental Toxicology and Chemistry.
W. C. Bridges received his B.S. degree from the University of North Carolina in 1980 and his M.S. degree and Ph.D. from the University of Nebraska in 1982 and 1984, respectively. He has been an assistant professor at Clemson University from 1984 to 1988, an associate professor from 1988 to 1995, and is currently a professor. He has authored approximately 125 publications and 70 presentations in collaboration with students and colleagues during his career at Clemson University.
John Rodgers received his Ph.D. from Virginia Polytechnic Institute and State University in 1977. Currently, he is a professor at Clemson University, director of the Ecotoxicology Program in the Department of Forestry and Natural Resources, and codirector of the Clemson Environmental Institute. His research involves a quest for accurate risk characterizations and development of sustainable risk mitigation tactics.