Monitoring particle size distribution for water treatment processes

Efficiencies of unit processes such as flocculation, sedimentation and filtration were analyzed based on particle size distribution in one of the several water treatment plants supplying Cracow (Poland). The predicted efficiencies determined based on concentration of volumetric suspension, nephelometric turbidity and absorbance were compared with each other. Interpretation of the results was proposed based on the Mie scattering theory. The results of theoretical analysis suggested much stronger influence of finer particles on absorbance and nephelometric turbidity than that of larger particles. The experimental results confirmed this suggestion. Hence, the more efficient removal of larger particles during the process resulted in a higher efficiency of the process based on the concentration of volumetric suspension than those predicted based on the nephelometric turbidity or absorbance. For a rapid filtration process, which is strongly dynamic, relation was analyzed for various filter run times.