Subsurface colloids in groundwater contamination: a mathematical model

In this paper, a new role of subsurface colloidal fines on the transport of contaminants in groundwater flows has been presented. Here, an equilibrium three-phase model based on colloidal induced release, migration and finally capture of these colloidal fines at pore constrictions has been developed. This model is more realistic than the existing models in that the physics of release, migration and finally capture at pore constrictions leading to plugging phenomenon has been adequately incorporated. Presence of colloids can either facilitate or inhibit the spreading of contaminants depending on the values of the parameters, such as the inlet colloid concentration, the release coefficient and more significantly on the sensitivity of the permeability to the concentration of captured fines at the pore constrictions. For a range of conditions, plugging of the porous media occurs resulting in retardation of contaminant transport. The plugging-based retardation of contaminant transport can be used to develop a new containment technique.