Charla Magistral (en inglés): Enhanced Spreading and Mixing to Improve In Situ Remediation of Contaminated Groundwater: Theory, Numerical Simulations, Laboratory Experiments, and a Field Test

During in situ remediation of contaminated groundwater, a chemical or biological amendment is introduced into the contaminated aquifer to react with and degrade the contaminant. Since the degradation reactions only occur where the amendment and contaminant are in sufficiently close proximity to react, the success of the remediation depends on the degree to which the amendment spreads and mixes into the contaminant plume. Spreading is defined as the change in the configuration of the plume; while mixing is defined as the pore-scale diffusion and small-scale mechanical dispersion step that brings the molecules together to react. Spreading can occur both passively due to heterogeneity, and actively by inducing time-varying flow fields. Spreading acts to elongate the interface between the amendment and contaminant plumes, thereby providing more opportunities for mixing, and therefore reaction, to occur. This seminar presents results of laboratory experiments of active spreading and the preliminary design of a field test to investigate the enhancement of degradation of chlorinated solvents promoted by active spreading. The behavior observed in the experiments are supported by theory and numerical simulation results.