Experimental investigation of suspended particles transport through porous media: particle and grain size effect

Particle and grain size may influence the transportation and deposition characteristics of particles within pollutant transport and within granular filters that are typically used in wastewater treatment. We conducted two-dimensional sandbox experiments using quartz powder as the particles and quartz sand as the porous medium to study the response of transportation and deposition formation to changes in particle diameter (d(s), with median diameter 18, 41, and 82 mu m) and grain diameter (d(p), with median diameter 0.36, 1.25, and 2.82 mm) considering a wide range of diameter ratios (d(s)/d(p)) from 0.0064 to 0.228. Particles were suspended in deionized water, and quartz sand was used as the porous medium, which was meticulously cleaned to minimize any physicochemical and impurities effects that could result in indeterminate results. After the experiments, the particle concentration of the effluent and particle mass per gram of dry sands were measured to explore changes in transportation and deposition characteristics under different conditions. In addition, a micro-analysis was conducted to better analyse the results on a mesoscopic scale. The experimental observation analyses indicate that different diameter ratios (d(s)/d(p)) may lead to different deposit formations. As d(s)/d(p) increased, the deposit formation changed from 'Random Deposition Type' to 'Gradient Deposition Type', and eventually became 'Inlet Deposition Type'.