3-DIMENSIONAL EXPERIMENTAL TESTING OF A 2-PHASE FLOW-MODELING APPROACH FOR AIR SPARGING

Air sparging has been used for several years as an in situ technique f or removing volatile compounds from contaminated ground water, but few studies have been completed to quantify the extent of remediation. To gain knowledge of the air flow and water behavior around air injectio n wells, laboratory tests and model simulations were completed al thre e injection flow rates (62, 187, and 283 lpm) in a cylindrical reactor (diameter = 1.2 m, depth = 0.65 m). Measurements of the air flux dist ribution were made across the surface of the reactor at 24 monitoring locations, six radial positions equally spaced along two orthogonal tr ansects. Simulations using a multiphase now model called T2VOC were co mpleted for a homogeneous, axisymmetric configuration. Input parameter s were independently measured soil properties. In all the experiments, about 75 percent of the flow injected exited the water table within 3 0 cm of the sparge well. Predictions with T2VOC showed the same. The a verages of four flux measurements at a particular distance from the sp arge well compare satisfactorily with T2VOC predictions. Measured nux values at a given radius varied by more than a factor of two, but the averages were consistent between experiments and agreed well with T2VO C simulations. The T2VOC prediction of the radial extent of sparging c oincided with the distance out to which air flow from the sparge well could not be detected in the reactor. The sparging pattern was relativ ely unaffected by the air injection rate over the range of conditions studied. Changes in the injection rate resulted in nearly proportional changes in flux rates.