Orthokinetic flocculation in rapid filtration

Quantitative measurements have been made of filter pore orthokinetic flocculation using a laboratory-scale model filter and a hydrophobic particle-nonionic polymer system. Interparticle collision efficiency factors, determined by Coulter Counter analysis, have been found to increase with shear rate in contrast with current theoretical interpretations. Comparative collision efficiency factors have been determined in jar test and capillary-tube apparatuses under equivalent conditions to the filter tests. In rapid filtration practice using cationic polymers, and at high shear rates (G_w > 150 s⁻¹) filter pore collision efficiencies are suggested as lying between those determined in tube flow (lower bound) and by jar test (upper bound).