A uniform shearing vibration membrane system reducing membrane fouling in algae harvesting

Abstract

Abstract When a membrane is used to harvest algae, membrane fouling caused by algae and extracellular organic matter (EOM) is a serious challenge. A uniform shearing vibration membrane (USVM) system was devised and applied to reducing membrane fouling in algae filtration. The shear rate produced by USVM is constant because of its uniform circular motion; thus, USVM could stably and significantly mitigate fouling. During the filtration experiments where the frequency was increased from 1 to 5 Hz, the transmembrane pressure (TMP) visibly reduced. Even at a relatively low frequency of 5 Hz, USVM still could stably filter algae and had only slight membrane fouling. Increasing the vibration frequency not only could significantly reduce reversible membrane fouling but could also reduce irreversible membrane fouling. Protein could cause more serious reversible membrane fouling, while humic substances could lead to more serious irreversible membrane fouling. In this study, USVM effectively reduced the deposition of algae cells, protein, polysaccharide and humic substances on the membrane as frequency increased.