Design of a two-dimensional model and investigation of DNAPL recovery by water and co-solvent flooding

A two-dimensional laboratory simulator was designed and assembled to investigate removal of dense non-aqueous phase liquid (DNAPL) contaminants from ground water by water flooding and neutral buoyant co-solvent flooding. Preliminary experiments indicated that optimum DNAPL removal was achieved during water flooding for viscous-to-capillary scaling ratios between 0.00075 and 0.001. The simulator was used to investigate effects of the direction of gradient flow on DNAPL removal efficiency by neutral buoyant co-solvent flooding. Results indicated that approximately 90 percent DNAPL was removed when injection was performed either in the direction of gradient flow or against it. However, injection in the direction of gradient flow was more efficient in terms of time and total co-solvent needed. Nevertheless, during injection in the direction of the flow more contamination occurred downstream due to dispersion. Results also indicated that size of the plume does not play an important role in the recovery efficiency of this system.