Filtration of polydisperse suspensions
The effect of particle polydispersivity in the influent suspension to granular media filters has been studied experimentally. Suspensions of spherical latex particles of sizes 0.09 μm, 0.944 μm and 7.04 μm were filtered through a porous bed of glass spheres, under well controlled physical and chemical conditions. Effluent concentrations and headloss development were monitored. The presence of small particles is observed to improve the removal of large particles. Relative particle removal appears to be predictable based on the surface area available in the bed for deposition to take place. Deposition morphology and relative distribution of the mass in the bed appear to play an important role in headloss development during filtration of polydisperse suspensions. If smaller particles are present in the filter influent, the practice of 'filtering to waste' should improve the initial removal of particles near 1 μm in diameter that might otherwise be poorly removed by clean filter beds.
