Air Sparging Remediation: A Study on Heterogeneity and Air Mobility Reduction

Key words: remediation, air sparging, NAPL, foam Contaminated groundwater is a widespread problem often requiring innovative technology to remediate. The purpose of this paper is to present the laboratory results of air sparging models. Initial tests used very fine porous media (glass beads-packed column) to represent a relatively homogeneous soil samples. Subsequent testing employed budded core samples taken from a site of interest to represent more realistic, heterogeneous samples. 1,1,1 Trichloroethane (TCA) was used as the dissolved contaminant to represent BTEX/ gasoline contamination; however, results obtained here can be applied to any NAPL-dissolved phase. A technique based on foam injection is proposed and is demonstrated to reduce air mobility. This reduction in air mobility has potential to improve contaminant removal. Laboratory results are compared with predictions of a numerical model, which is an advection-diffusion air sparge simulation model. Sensitivity analysis of the numerical model provides the range of some key parameters used to screen/evaluate air sparging as the remediation method for a given contaminated site of interest. Eventual scaleup of the model to an actual site application can be justified by the favorable results presented in this paper. BACKGROUND The efficiency of air sparging as a groundwater remediation process depends to a large extent on the contact time and contact area of air with contaminated water. A number of investigators have conducted laboratory or field studies, or numerical simulation, in order to better understand air distribution and a few have conducted studies to measure the removal rate of contaminants from groundwater. A majority of these studies chose mostly homogeneous porous media, either 2D/3D glass-beads or..