SEMINAR: Electrokinetic in situ oxidation remediation: From processes and parameters to implementation

Significant challenges remain in the remediation of low-permeability porous media (e.g. clays, silts) contaminated with dissolved and sorbed organic contaminants, with current remediation technologies, such as in-situ chemical oxidation (ISCO), often being ineffective. 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), however there is still a poor understanding of the relative importance of the system parameters and processes, and the ways in which to optimize the technology.

In this study, a numerical model was developed that simulates groundwater flow and multi-species reactive transport under both hydraulic and electric gradients. Coupled into an existing, previously verified reactive transport model, the PHT3D-EK model was verified against analytical solutions and data from experimental studies. The numerical model was used to investigate the effect of the voltage gradient, the sensitivity of electrokinetic, hydraulic and engineering parameters as well as the influence of aquifer heterogeneity on the technology. Numerical modelling was also conducted to identify and evaluate alternative configurations and implementation approaches of the EK-ISCO treatment process. Investigated variants of treatment configurations included a series of one- and two-dimensional electrode configurations, several alternative locations for oxidant injection and horizontal electrodes.