Keywords: ultrafiltration, concentration polarisation, membrane fouling, rotating disk membranes, RDM, cross–flow membranes, shear enhanced membrane filtration, hydrodynamics, permeate flux, solute rejection, power consumption
Performance comparison of rotating disk ultrafiltration membrane module, a high shear device with cross–flow module
Apart from plenty of advantages, the main disadvantage of ultrafiltration is rapid flux decay due to concentration polarisation and membrane fouling. The purpose of this work is to overcome this problem employing shear enhanced membrane filtration technique. To accomplish this, two different membrane modules were used; one was a standard cross–flow membrane module and the other one was the stirred rotating disk membrane (RDM) module. A detailed comparative study between these two membrane (PES) modules with different operating conditions was made using 500 ppm BSA solution. Hydrodynamic studies on permeate flux and solute rejection characteristics have been made. It was observed that membrane rotation of 50 rpm was sufficient to alleviate membrane fouling and concentration polarisation. Comparative study has shown that at trans–membrane pressure (TMP) 196 kPa, permeate flux was two times higher for RDM with 50 rpm membrane speed than that of cross–flow membrane module. However, the limitation of the rotating disk systems could be their limited membrane area per unit volume and higher power consumption.