Transport processes of suspended particles in saturated porous media by column seepage tests

The penetration processes of a typical silica powder in saturated porous media composed of quartz sands are studied by column seepage tests. The tests consider 6 kinds of particle sizes (i.e., 10, 15, 20, 25, 33, 47 μm), 3 particle concentrations (i.e., 0.2, 0.5, 0.8 mg/mL), 3 flow velocities (i.e., 0.087, 0.173, 0.260 cm/s), and different flow directions (i.e., downward, horizontal, upward), etc. According to the test results, the physical mechanisms of suspended particle migration such as hydrodynamics, dispersion and deposition are discussed. The studies show that for the same seepage velocity, the peak concentrations of penetration process decrease generally with the increase of particles size. On the other hand, the effect of hydrodynamic processes on particle transport is increased obviously with the increase of flow velocity while the effect of particle size is degenerated correspondingly. Besides, there exists a critical injected concentration, and beyond this value the relative concentration in the effluent begins to decrease, which is related to the logging of pores of porous media due to a large number of deposited particles.