Comparison between rotating disk and vibratory membranes in the ultrafiltration of oil-in-water emulsions

The purpose of this work is to compare the effects of hydrodynamic parameters on the permeate flux provided by two different dynamic filtration systems using same membrane material and same fluids. Tested systems were rotating disk module and a VSEP pilot with a circular vibrating membrane. Test fluid consisted of oil in water emulsion of cutting fluid. The characteristic shear rate was taken to be the maximum one at the membrane. It was varied by changing the rotation speed of the disk or by changing the vibration frequency of the VSEP. The highest permeate fluxes were obtained with rotating disks equipped with vanes. With the VSEP, the flux decreases with time. However, the fouling limitation disappears completely for a disk equipped with vanes. In the two systems, the flux is mainly governed by the maximum shear rate and not by details of internal flow and can be increased to very high levels by increasing rotation speed or vibration amplitude.