A novel vortex flocculation reactor for efficient water treatment: Kinetic modeling and experimental verification

We designed a novel vortex flocculation reactor with column-cone-column structure by adding vortex generators to form the micro-vortices to improve the flocculation efficiency. The vortex generators, actually wedge-shaped baffles, act as turbulence components to generate large flow resistance, thus reducing the size of the vortex to approach that of the floc. The inverted cone-cone-inverted cone structure in small-vortex flow flocculation zone prompts the fluid to form boundary layer dissociation phenomenon, thereby enhancing the relative motion of floc particles. The numerical simulation results of flow field structure indicated that the fluid presented a multiphase flow of "swirl flow-vortex flow-plug flow"; hence the fluid characteristic changed step by step. Moreover, the multistage velocity gradient of the fluid in different flow layers enhanced the probability of floc particles collision, thus strengthening the flocculation. Then the lab-scale vortex flocculation reactor was man-ufactured to conduct flocculation tests. The results revealed that the vortex flocculation reactor took the reaction time of only 10 s to achieve a superior chemical oxygen demand removal rate of 93.7%. The vortex flocculation reactor, based on the multiphase flow and multistage velocity gradient reinforcement flocculation strategy, can offer an effective way to improve the flocculation efficiency.