Transport and deposition of suspended particles in saturated porous media: hydrodynamic effect

International audienceThis paper discusses the transport and deposition rate of suspended particles in saturated porous media. The laboratory study used a column where the porous media were subjected to a steady state flow. Two materials were used: gravel and glass beads. Silt particles of 14 µm mean diameter were used as suspended particle tracer. By means of short pulse injection, transport tests using suspended particles and a conservative tracer were performed. The breakthrough curves were well described with the analytical solution of the convection-dispersion equation with first-order deposition rate. The experiments were performed under different flow rates. The particle size distribution, the porous media, and the flow rates tested were the main factors retained in this study to investigate the mechanisms governing the transport and deposition kinetics. The results showed the existence of a flow rate beyond which suspended particles travel faster than the conservative tracer. A decrease of the deposition rate of suspended particles beyond a critical flow velocity is observed too. Such behaviour makes us think of the couple hydrodynamic-gravity forces at high flow rates. As the hydrodynamic force increases particle deposition rates are reduced due to the effect of hydrodynamic forces inhibiting the deposition