Structural design of a rotating disk dynamic microfilter in improving filtration performance for fine particle removal

Abstract

This study investigated the selection of optimal operating conditions and the design of efficient rotating disk structures for removing particles from seawater. The distributions of fluid velocity and shear stress on the membrane surface under various operating conditions were simulated using computational fluid dynamics. Type 1 rotating disk had two vans, Type 2 rotating disk had four vanes shaped identically to those of the Type 1 rotating disk, and Type 3 rotating disk had two vanes with circular orifices located at the center of each vane. The simulated results indicated that the disk rotation speed is the main factor affecting shear stress on the membrane surface. Cake mass and filtration flux were estimated from shear stress and were calculated using empirical equations. The results showed that flux in Type 1 increased by 28% when the disk rotation speed increased from 1000 to 3000 rpm; the installation of extra vanes caused an ineffective increase in flux at 3000 rpm. Although Type 2 exhibited the highest filtration performance and the lowest cake resistance, Type 3 is the optimal design because it exhibited the highest specific filtration flux among all tested rotating disk types. The rotating disk with two vanes with a circular orifice at a low disk rotation speed demonstrated the optimal design and operating conditions for removing particles from seawater, because it resulted in high filtration fluxes and relatively low power consumption.