Coupling Effects of Flow Velocity and Ionic Strength on the Clogging of a Saturated Porous Medium

摘要

In this study, both the effects of suspension ionic strength and flow velocity on deposition and the clogging phenomena are investigated. Experimental tests are performed in the case of the silt microparticle transport through a saturated sand column with the presence of repulsive interactions. The specific size of these particles is chosen to ensure the presence of both physicochemical and mechanical retention mechanisms. The injection of particle suspension is conducted for long durations at different ionic strength and flow velocities. The deposition rate and the porous media clogging mainly depend on the ionic strength. An increase in the ionic strength causes an increase in the deposition rate and a reduction of the hydraulic conductivity which leads to the progress of the clogging phenomenon through the porous medium. Experimental analyses show the presence of a clogging front whose spatial distribution and temporal progress depend on the suspension ionic strength. Its velocity advancement is proportional to the ionic strength. Within the validity range of Darcy's law, the dynamics of deposition and clogging also depend on the flow rate. In particular, the retention of silt microparticles is more important for low flow velocities. The influence of the physicochemical effects on the deposition rate and therefore sand texture clogging is more significant at low flow rates.