Experiment research on physical clogging mechanism in the porous media and its impact on permeability

Abstract

The physical clogging of porous medium is a significant problem that impacts the performance of infiltration systems. Although the physical clogging has been extensively studied, the mesoscopic mechanism and clogging dynamic in the porous medium are still unclear. This paper focuses on the migration characteristic and physical clogging mechanism of suspended solid (SS) particles in gravel and zeolite columns. The results indicate that the permeability of the filter medium significantly decreases at the initial stage of SS infiltration and reduces to a steady value as the accumulated SS load increases. The permeability of the porous medium decreases as the particle size of the filter medium decreases, while lower particle sphericity and coarser particle texture also result in a reduction in the permeability of the porous medium. X-ray computed tomography was used to obtain images during the infiltration of the SS particles through the substrates. Due to the formation of a clogging layer, the intrusion of subsequent SS inflow can be prevented, leading to the formation of a blanket depositional layer. The ratio between the particle size of the filter medium and the SS particles controls the migration of the SS particles within the porous medium. Additionally, in this experimental study, the threshold is affected by the particle shape and texture of the filter medium. Considering the reduction in the permeability of porous medium by the clogging layer, a simple double-layered analytical model that considers SS accumulation was proposed to estimate the variation in the permeability, which agrees well with the experimental measurements.