Effects of Process Control Changes on Aquifer Oxygenation Rates During In Situ Air Sparging in Homogeneous Aquifers |
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| Authors: | Kyle W. Rutherford Paul C. Johnson |
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| Affiliation: | Kyle Rutherford received his master's degree in civil and environmental engineering from Arizona State University in December 1995, specializing in contaminant fate and transport. Rutherford was formerly an officer in the U.S. Navy Civil Engineer Corps and is a professional engineer in Arizona and Indiana. He currently manages environmental projects for Groundwater Technology Inc. in Tempe, Arizona.;Dr. Paul C. Johnson is an associate professor in the Department of Civil and Environmental Engineering at Arizona State University (ASU) in Tempe, Arizona. (Department of Civil and Environmental Engineering, Arizona State University, Tempe, AZ 85287-5306). He received his B.S. and Ph.D. degrees in chemical engineering from the University of California at Davis and Princeton University, respectively. His research and teaching interests focus on the development of cost-effective and innovative solutions to problems related to environmental protection, environmental restoration, and environmental risk analyses, including issues such as aquifer protection, risk and exposure assessment, remedial method development, and waste management. Prior to joining the faculty at ASU, he was a senior research engineer at Shell Oil Co.'s Westhollow Research Center from 1987 to 1994. |
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| Abstract: | In situ air sparging is used to remediate petroleum fuels and chlorinated solvents present as submerged contaminant source /ones and dissolved contaminant plumes, or to provide barriers to dissolved contaminant plume migration. Contaminant removal occurs through a combination of volatilization and aerobic biodegradation: thus, the performance at any given site depends on the contaminant and oxygen mass transfer rates induced by the air injection. It has been hypothesized that these rates are sensitive to changes in process flow conditions and site lithology, but no data is available to identify trends or the magnitude of the changes. In this work, oxygenation rates were measured for a range of air injection rates, ground water flow rates, and pulsing frequencies using a laboratory-scale two-dimensional physical model constructed to simulate a homogeneous hydrogeologic setting. Experiments were conducted with water having low chemical and biochemical oxygen demand. Results suggest the following: that there is an optimum air injection rate: advective How of ground water can be a significant factor when ground water velocities are > 0.3 m/d: and pulsing the air injection had little effect on the oxygenation rate relative lo the continuous air injection case. |
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