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Remediation of Chlorinated Solvent Plumes Using In-Situ Air Sparging—A 2-D Laboratory Study
ENGEO Incorporated, 2010 Crow Canyon Place, Suite 250, San Ramon, CA 94583, USA
Department of Civil & Materials Engineering, University of Illinois at Chicago, 842 West Taylor Street, Chicago, IL 60607, USA
* Author to whom correspondence should be addressed.
Received: 1 March 2011; in revised form: 21 May 2011 / Accepted: 10 June 2011 / Published: 16 June 2011
Abstract: In-situ air sparging has evolved as an innovative technique for soil and groundwater remediation impacted with volatile organic compounds (VOCs), including chlorinated solvents. These may exist as non-aqueous phase liquid (NAPL) or dissolved in groundwater. This study assessed: (1) how air injection rate affects the mass removal of dissolved phase contamination, (2) the effect of induced groundwater flow on mass removal and air distribution during air injection, and (3) the effect of initial contaminant concentration on mass removal. Dissolved-phase chlorinated solvents can be effectively removed through the use of air sparging; however, rapid initial rates of contaminant removal are followed by a protracted period of lower removal rates, or a tailing effect. As the air flow rate increases, the rate of contaminant removal also increases, especially during the initial stages of air injection. Increased air injection rates will increase the density of air channel formation, resulting in a larger interfacial mass transfer area through which the dissolved contaminant can partition into the vapor phase. In cases of groundwater flow, increased rates of air injection lessened observed downward contaminant migration effect. The air channel network and increased air saturation reduced relative hydraulic conductivity, resulting in reduced groundwater flow and subsequent downgradient contaminant migration. Finally, when a higher initial TCE concentration was present, a slightly higher mass removal rate was observed due to higher volatilization-induced concentration gradients and subsequent diffusive flux. Once concentrations are reduced, a similar tailing effect occurs.
Keywords: air sparging; groundwater; contamination; non-aqueous phase liquids; soils; remediation; pollution
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Adams, J.A.; Reddy, K.R.; Tekola, L. Remediation of Chlorinated Solvent Plumes Using In-Situ Air Sparging—A 2-D Laboratory Study. Int. J. Environ. Res. Public Health 2011, 8, 2226-2239.
Adams JA, Reddy KR, Tekola L. Remediation of Chlorinated Solvent Plumes Using In-Situ Air Sparging—A 2-D Laboratory Study. International Journal of Environmental Research and Public Health. 2011; 8(6):2226-2239.
Adams, Jeffrey A.; Reddy, Krishna R.; Tekola, Lue. 2011. "Remediation of Chlorinated Solvent Plumes Using In-Situ Air Sparging—A 2-D Laboratory Study." Int. J. Environ. Res. Public Health 8, no. 6: 2226-2239.