Laboratory Scale Analysis of Aquifer Remediation by In-Well Vapor-Stripping: 1. Laboratory Results

Ori Gonen and Haim Gvirtzman *

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ABSTRACT

Figure 1

Figure 1

Figure 1

This study is a laboratory test of the aquifer remediation concept proposed by Gvirtzman and Gorelick (1992) that involves the removal of volatile organic compounds (VOCs) dissolved in groundwater. The principle is to inject air into a well, creating air-lift pumping, which is used as a means of in-well vapor stripping. The partially treated water is separated from the VOC vapor and infiltrates back to the water table. A laboratory-scale aquifer model containing a remediation-well prototype was used to trace VOC removal over time. The removal rates of trichloroethylene (TCE), toluene and chloroform were monitored using eight triple-level observation wells. The continuous decrease of VOC concentrations in space and time was interpreted based on three processes: (i) the diffusional mass transfer between the contaminated water and the air bubbles during their rise within the well; (ii) the desorption of VOCs from the solid matrix to the water phase; and (iii) the flow field in the saturated zone driven by the continuous water circulation between the pumping well and the recharging area. In the second of these companion papers (Pinto et al., this issue), 3-dimensional flow and transport modeling with inter-phase mass transfer is carried out to simulate these processes.


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