Membrane fouling behavior and its control in a vibration membrane filtration system related to EOM secreted by microalgae

Abstract

The mechanism of the effects of extracellular organic matter (EOM) on membrane fouling in a vibration membrane system remains unclear, which partially impedes the membrane efficiency enhancement in the process of microalgae harvesting. This work conducted a systematic study on the fouling effects of two typical foulants in EOM, bovine serum albumin (BSA) and sodium alginate (SA) at different vibration frequencies. The results of water flux behavior revealed that vibration could effectively alleviate membrane fouling under shear action, and the water flux reached a peak when the BSA/SA was 3:1. By analyzing the bulk and permeate solution and characterizing the fouled membrane surface, it was proved that there was a strong interaction between the BSA/SA mixture and the PES membrane. Thermodynamic and hydrodynamic forces analysis results suggested that the BSA/SA of 3:1 exhibited superior membrane antifouling performance and vibration could effectively mitigate membrane fouling. Further, the relationship between the BSA/SA mixture and the PES membrane was confirmed by molecular dynamics (MD) simulation from a microscopic point of view. The results revealed the reason why the BSA/SA mixture generated membrane fouling in the membrane system. Moreover, the MD simulation strongly proved that when the BSA/SA was 3:1, the membrane fouling was the lowest and the water flux was the highest. Overall, regulating the concentration ratio of the main substances in the EOM and optimizing the feeding conditions, should be a feasible method for controlling membrane fouling to break through the technical bottleneck of microalgae harvesting technology.