Influence of vibration of flat-sheet membrane modules on fouling in MBRs

Vibration of flat-sheet membrane modules by aeration in the MBRs is thought to influence the increase rate of the transmembrane pressure caused by membrane fouling. In a laboratory scale experiment, influence of the thickness of flat-sheet membrane module on transmembrane pressure increase rate was investigated using artificial activated sludge and three kinds of flat membranes with varying the thickness. The magnitude of the vibration of the membrane sheets was measured by using a laser displacement meter. Although the vibration of thicker flat membrane was smaller, the rate of transmembrane pressure increase was smaller in the thicker module, The shear stress on the surface of membrane sheet caused by aeration was measured and, it was found that larger vibration displacement of membrane sheet causes smaller shear stress on membrane sheet, the mechanism of which was explained by the inhibition of water flow over membrane sheets by the vibration of membrane sheets.