Dynamic microfiltration with a perforated disk for effective harvesting of microalgae

Abstract

A dynamic microfiltration system has been receiving increasing attention as a means of preventing membrane fouling phenomena that reduce microalgae harvesting efficiency. This study describes the addition of a perforated disk to a dynamic microfiltration system for effective membrane-based microalgae harvesting. Fluid velocity near the membrane surface and shear stress on the membrane surface, as generated by different disks and rotation speeds, were simulated by computational fluid dynamics software, SolidWorks. A high correlation of shear stress on the membrane with microalgae harvesting efficiency was validated by a simulation-based empirical approach. Notably, fluid velocity near the membrane surface and average shear stress on the membrane surface with the perforated disk were approximately 2- and 7-fold, respectively, higher than observed with an unperforated disk. In empirical-experimental microfiltration of Chlorella vulgaris, the perforated disk (800rpm) showed a 2-fold-higher plateau permeate flux of 381L/m2/h compared with the unperforated disk (800rpm), enabling a 2-fold-greater alleviation of microalgal fouling at the same rotation speed. The perforated disk was found to be an effective generator of high shear stress in dynamic microfiltration, resulting in improved filtration during harvesting of microalgae.