[Truncated abstract] Significant challenges remain in the remediation of low-permeability porous media (e.g. clays, silts) contaminated with dissolved and sorbed organic contaminants. Current remediation technologies, such as in situ chemical oxidation (ISCO), are often ineffective and the treatment region is limited by very slow rates of groundwater flow (advection) or molecular diffusion. Recent laboratory-scale studies have highlighted the potential for utilising electrokinetic transport, as induced by the application of an electric field, to deliver a remediation compound (e.g. permanganate, persulfate) within heterogeneous and low-permeability sediments for ISCO (termed EK-ISCO). The underlying understanding of EK-ISCO is much newer than other electrokinetic and remediation technologies, and there is still a poor understanding of the relative importance of the system parameters and processes in EK-ISCO remediation, and the ways in which to optimize the technology. Process-based numerical modelling of the coupled flow, transport and reaction processes can provide important insights into the prevailing controls and feedback mechanisms and therefore guide the optimisation of EK-ISCO remediation efficacy. In this study, a numerical model was developed that simulates groundwater flow and multi-species reactive transport under both hydraulic and electrical gradients. Coupled into an existing, previously verified reactive transport model, the PHT3D-EK model was verified against analytical solutions and data from experimental studies. Application of the model showed that ISCO amendment injection resulted in the voltage gradient adjacent to the cathode decreasing below a linear gradient, producing a lower achievable concentration of the amendment in the medium. Even with lower achievable concentrations, analysis showed that EK-ISCO remediation is still feasible due to its ability to deliver a sufficient mass flux in low-permeability media.
|Qualification||Doctor of Philosophy|
|Publication status||Unpublished - 2011|