  Groundwater pollution poses a significant threat to environmental
sustainability during urbanization. Existing remediation methods like
pump-and-treat and electrokinetics have limited ion transport control. This
study introduces a coupled advection-diffusion-electromigration system for
controlled ion transport in the subsurface. Using the Lattice-Boltzmann-Poisson
method, we simulate ion transport in various two- and three-dimensional porous
media. We establish an ion transport regime classification based on the Peclet
number (Pe) and a novel Electrodiffusivity index (EDI). By manipulating the
electric potential, hydrostatic pressure, and ion concentration, we identify
four transport regimes: large channeling, uniform flow, small channeling, and
no flow. Large channeling occurs when advection dominates, while uniform flow
arises when diffusion and electromigration are more prevalent. Small channeling
happens when the advection opposes electromigration and diffusion, and no flow
occurs when the advection or electromigration impedes ion transport via
diffusion. Simulations in heterogeneous models confirm these transport regimes,
highlighting the influence of pore size variation on transport regimes.
Consequently, $Pe$ and $EDI$ must be tailored for optimal transport control.
These findings enable better control over ion transport, optimizing processes
such as heavy metal removal, bioremediation, and contaminant degradation in
groundwater management.
