The interaction between microalgae and membrane surface in filtration by uniform shearing vibration membrane

Abstract Membrane fouling is an inevitable problem in the process of using membrane technology to filtrate microalgae. In the present study, a uniform shearing vibration membrane (USVM) system was proposed and utilized in algae filtration. USVM is a uniform circular motion whose induced shear rate is constant, which is more conducive to the mitigation of fouling. In the filtration experiments, as the frequency increased from 1 to 5 Hz, the membrane fouling decreased obviously. When the frequency is 5 Hz, USVM can filtrate algae with a constant flux and less membrane fouling, and few algae deposited on the membrane. Based on “extended Derjaguin, Landau, Verwey, Overbeek” (XDLVO) theory, the interaction force acting on algae and membrane was calculated to explain the mechanism that USVM can filtrate algae stably at the frequency of 5 Hz, and why the increased frequency could effectively mitigate membrane fouling. At 5 Hz, the initial lift force was 0.123 nN, the total interaction force was the repulsive force, and thus the algae could be prevented from being deposited on the membrane to reduce the membrane fouling. As the frequency decreased, the initial lift force and total interaction force declined, which could not effectively prevent algae deposition.