Groundwater Cleanup by In-Situ Sparging. X. Air Channeling Model for Biosparging of Nonaqueous Phase Liquid

Abstract

A column model is developed to simulate the removal and biodegradation of dissolved and nonaqueous phase liquid (NAPL) volatile organic compounds (VOCs) from contaminated aquifers by biosparging. The model assumes that the injected air moves through the aquifer in persistent channels and that NAPL must dissolve and move to these channels by diffusion and dispersion. The dependence of model results on several of the parameters of the model is investigated, and suggestions for optimizing biosparging system operations are made. The removal of NAPL VOCs of quite low solubility (such as alkanes) from smear zones below the water is modeled, and is found to be an extremely slow process. Drawing down the water table to below the smear zone by pumping is suggested as a possible solution.