ASSESMENT OF FOULING POTENTIAL OF BIOPOLYMERS ISOLATED FROM SURFACE WATER USING QUARTZ CRYSTAL MICROBALANCE WITH DISSIPATION MONITORING（QCM-D）

Abstract

 While water purification using membranes has many advantages over conventional treatment, membrane fouling is still a major problem. Recent studies have suggested that high-molecular-weight hydrophilic organic matters called biopolymers play an important role in the evolution of membrane fouling. In this study, biopolymers were collected and isolated from several drinking water sources with different characteristics, and the properties of the isolated biopolymers were investigated. Degrees of membrane fouling caused by the biopolymers were clearly different depending on the sources, indicating that the characteristics of biopolymers varied with the source. Differences in biopolymers were evident in those molecular weight distribution measurements using LC-OCD and infrared spectra. It was also postulated that biopolymers mainly composed of polysaccharides tended to cause severe irreversible fouling. Analysis of the biopolymers using quartz crystal microbalance with dissipation monitoring(QCM-D) demonstrated an interesting result; the order of affinity of each isolated biopolymers to the membrane material (i.e. PVDF) was consistent with the order of degrees of membrane fouling observed in the membrane filtration test. In addition, viscoelasticity of the biopolymers assessed by QCM-D may explain reversibility of membrane fouling.