Physical Clogging of Uniformly Graded Porous Media Under Constant Flow rates

Abstract

This study investigated the physical clogging of uniformly graded porous media under constant flow rates using natural porous media and suspensions. The porous media selected for this experimental study was a fine-to-medium sandy soil fractioned into thirteen uniformly graded beds: seven unisize beds and six uniform beds. The physical clogging of the beds was studied using two types of silt suspensions as along with two suspension concentrations and three water discharges. It was found that the permeability reduction due to physical clogging $$[(K_\mathrm{i} - K_\mathrm{t})/K_\mathrm{i}]$$ increased with decreasing $${D}_{15}/{d}_{85}$$ ratios until a critical value of $${D}_{15}/{d}_{85}$$ , after which a surface mat of suspension was formed on the porous media. It was also found that the value of reduced permeability at any time (at any number of pore volumes of injected suspension-laden water), $$K_\mathrm{t}$$ , is directly proportional to square of $${D}_{15}$$ and inversely proportional to $${C}_{\mathrm{u}}$$ of the porous media and $${d}_{85}$$ of suspensions. The effects of suspension type and flow rates on physical clogging seemed to depend on the size of the pores in the porous media.