Effect of particle concentration on the entire cycle of filtration

Influent particle concentration is one of the physical parameters that influence the overall performance of a deep bed filter. Natural waters with varying turbidity have varying effect on filtration. Experimental and theoretical studies on the effect of concentration on clean bed filter efficiency and ripening stage efficiency have been reported in the literature. However, a comprehensive study on the effect of influent concentration on the transient stage of filtration is not documented. In addition, it is not understood in what units the concentration should be expressed in the mathematical models: the mass, number or surface area of the particles? In this present study, submicron polystyrene latex beads of sizes 0.46 μm and 0.825 μm were used to study the effect of concentration on the entire cycle of filtration. Experiments were carried out at constant mass, number and surface area as influent concentrations in order to observe the variation in filtration of the two sizes of particle. At constant mass concentrations, the initial removal was found to be higher for smaller particles (0.46 μm) (in the submicron range); but when the number or surface area of particles was considered, it was found to be higher for larger particles (0.825 μm). The transient stage removal was found to increase with an increase in particle size, either with constant mass, number or surface area as an influent concentration. The Vigneswaran and Chang (1986) model was used to quantify the results. The model parameters estimated using the experimental results are useful in quantifying and understanding the performance of the filter.