LABORATORY-SCALE ANALYSIS OF AQUIFER REMEDIATION BY IN-WELL VAPOR STRIPPING - 1 - LABORATORY RESULTS

This study is a laboratory test of the aquifer remediation concept pro posed by Gvirtzman and Gorelick (1992, Transp. Porous Media, 8: 71-92) , which involves the removal of volatile organic compounds (VOCs) diss olved in groundwater. The principle is to inject air into a well, crea ting air-lift pumping, which is used as a means of in-well vapor strip ping. 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 c hloroform were monitored using eight triple-level observation wells. T he continuous decrease of VOC concentrations in space and time was int erpreted based on three processes: (1) the diffusional mass transfer b etween the contaminated water and the air bubbles during their rise wi thin the well; (2) the desorption of VOCs from the solid matrix to the water phase; (3) the flow field in the saturated zone driven by the c ontinuous water circulation between the pumping well and the rechargin g area. In a companion paper (Pinto et al., 1997), three-dimensional f low and transport modeling with inter-phase mass transfer is carried o ut to simulate these processes. (C) 1997 Elsevier Science B.V.