GROUNDWATER CLEANUP BY IN-SITU SPARGING - XIII - RANDOM AIR CHANNELS FOR SPARGING OF DISSOLVED AND NONAQUEOUS PHASE VOLATILES

A mathematical model is developed to simulate the sparging of dissolve d volatile organic compounds (VOCs) and nonaqueous phase liquid (NAPL) from contaminated aquifers. The sparging air moves through the aquife r In persistent, rancom channels, to which VOC must move by diffusion/ dispersion to be removed. The dependence of the rate of remediation on the various model parameters is investigated and some practical concl usions are reached regarding the operation of air sparging wells for a quifer remediation. VOCs of low water solubility (such as alkanes) and present as NAPL are found to be removed by air sparging much more slo wly than VOCs of higher water solubility (such as benzene, toluene, et hylbenzene and xylenes) and present as NAPL, due to the very small max imum concentration gradients which can be maintained around droplets o f the former. These small concentration gradients result in very slow rates of NAPL solution.