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This study investigates various aspects of in situ chemical oxidation (ISCO) schemes based on MnO4-. Batch experiments show that the interaction between MnO4-, and sediment solids will not only consume the reactant, but also can release toxic metals into ground water. Various column and flow tank experiments were conducted to examine the capacity and efficiency of the oxidation scheme. Oxidation was capable of destroying chlorinated ethylenes in aqueous phase. MnO4- oxidation performs better in removal of residual DNAPL than pooled DNAPL. In zones of high NAPL saturation, Mn oxide precipitates causing pore plugging and permeability reduction. These changes potentially could cause the remedial action to fail. In an effort to mitigate the precipitation, experiments have been carried out to investigate possibilities of delaying the formation of colloidal Mn oxide and to remove the precipitates once formed. The investigation begins with the identification of the Mn oxide mineral structure and the determination of the chemical properties of the solid. Phosphate ion was added to the reaction in an attempt to slowdown colloidal formation due to its high charge and the tendency to sorb on surfaces. The results indicate that the presence of phosphate ion can lower the rate of colloid formation. However, the magnitude of effects due to the addition of phosphate is limited by the ionic strength increase and the pzc (point of zero charge) of the mineral. The dissolution kinetics of birnessite was evaluated using solutions of citric acid, oxalic acid, and EDTA. The results showed that the addition of an organic acid could greatly increase the dissolution rate of birnessite. The dissolution mechanism involves proton and ligand-promoted dissolution and reductive dissolution. A permanganate reactive barrier system (PRBS) was designed and a proof-of-concept experiment was carried out in the laboratory. The experiment demonstrated how the PRBS could delivery MnO4- at a stable, constant, and controllable rate. This idea could be developed as a long-term reactive barrier for the remediation of chlorinated solvents in plume.

This thesis contains the study of two techniques that could be used in the remediation of dense nonaqueous-phase liquids (DNAPL) within typical aquifers: (1) the use of partitioning tracers to locate contaminated zones within the aquifer, estimate the volume of contaminant within the tracer swept volume, and/ or assess a remediation process performance, and (2) the use of surfactant enhanced aquifer remediation to remove contaminant from the aquifer. A partitioning interwell tracer test is where tracers are injected into an aquifer through one well and produced from another. A chromatographic lag of the tracers is observed in the produced fluid. The magnitude of the lag depends on the size of the tracer partition coefficient. This chromatographic lag can be used to note the presence of a contaminant and estimate the volume of contaminant between the injection and production wells. Performing this test before and after remediation can tell how much of the contaminant was removed. Surfactants can be used in a remediation effort to either enhance solubilization of existing contaminant or mobilize the contaminant trapped in the free phase. Each contaminant encountered requires that phase behavior experiments be performed to predict the behavior of the surfactant with the contaminant, the groundwater in the aquifer, varying amounts of salts, and any chemicals added to the surfactant solution such as co-solvents or polymer. Xanthan gum was used in the surfactant solution to enhanced the sweep efficiency of the displacement of the groundwater with the surfactant solution. The polymer was used in phase behavior studies, surfactant floods, and tracer tests. Several batch phase behavior studies were performed. Two different contaminants were examined, (1) trichloroethylene and (2) a field contaminant obtained from Hill Air Force Base, Utah. Several column experiments using soil from three field sites were conducted to assess the performance of either tracers, surfactants or both. The results of these studies and how they relate to the remediation of dense nonaqueous-phase liquid are the main objective of this thesis.