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Using a process-based approach, a pilot-scale constructed wetland system was designed and built for treating water produced from an oil field in sub-Saharan Africa. The characteristics of the oil field-produced water were compared with water quality guidelines for irrigating crops and watering livestock to identify constituents of concern (COC) requiring treatment. The COC identified in the produced water include oil, grease, and metals (Zn, Ni, Fe, Mn). A pilot-scale constructed wetland treatment system was then designed and built based on biogeochemical pathways (i.e., sorption, oxidation, and reduction) for transferring and transforming the identified COC to achieve target concentrations meeting water quality guidelines. The pilot-scale treatment system consisted of three series of wetland cells, with four cells in each series. Two series of subsurface flow wetland cells were constructed with each cell having a two-layer hydrosoil of pea gravel and medium-size gravel planted with Phragmites australis. In addition, a series of free water surface wetland cells was constructed, with each cell containing sandy hydrosoil and planted with Typha latifolia. The design allows adjustment of parameters (i.e., hydraulic retention time and organic content of the hydrosoil) to promote the conditions needed to achieve treatment of COC through the identified biogeochemical pathways. This study provides an example of the design and construction of a pilot-scale wetland treatment system using a process-based approach.
Minh Phung Pham received her B.S. degree in environmental geology in 2006 from Clemson University. In 2009, she earned her M.S. degree in hydrogeology from Clemson University. Her master's thesis focused on water reuse and applying constructed wetland systems to treatment of oil field-produced water. Currently, she is a graduate student pursuing her doctorate at the Scripps Institution of Oceanography, where her research interests combine hydrogeology and plate tectonics.
James Castle is a professor in the Department of Environmental Engineering and Earth Sciences at Clemson University, where he conducts research on geologic and environmental aspects of energy resources. Before joining Clemson University in 1995, he was employed for 17 yr by Cabot Oil and Gas and Chevron. He received his Ph.D. from the University of Illinois at Urbana-Champaign.
John Rodgers received his Ph.D. from Virginia Polytechnic Institute and State University. 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 current research involves a quest for accurate risk characterizations and the development of sustainable risk mitigation tactics.