Intensification of membrane microfiltration using oscillatory motion

Mass transfer limitations at solid liquid interfaces caused by surface fouling and concentration polarization are the main reasons for limiting the performance of many membrane separation processes. In this investigation, intensification of membrane microfiltration was accomplished by oscillating the membrane along its surface at moderate frequencies (≤25 Hz) and low amplitudes (<0.03 m) while maintaining constant transmembrane pressure using a feedback control scheme. The enhanced oscillatory shear generated at the membrane fluid interface resulted in a continuous de-fouling of the membrane surface leading to significant improvement in microfiltration performance. Increasing oscillation frequency was found to have stronger effect on increasing filtration flux than its amplitude. Approximately three folds increase in filtration flux was achieved using the above approach. Correlation of the flux to the oscillation frequency and amplitude was developed (R2 = 0.98) and the results were compared with both dynamic as well as conventional cross flow filtration techniques.

► Intensification of membrane microfiltration can be accomplished by membrane oscillations along its surface.
► Up to three folds increase in filtration flux was achieved using the above approach at moderate frequencies (≤25 Hz) and low amplitudes (<0.03 m).
► Oscillation frequency has stronger effect on increasing filtration flux than its amplitude.
► The power ratio of the frequency to amplitude is greater than 1.5 predicted by the one third power law.
► The above suggests that the assumption of a direct correlation between the flux and the shear rate under oscillatory conditions needs further investigation.