Effect of vibration on fouling propensity of hollow fiber membranes in microfiltration and membrane distillation

Abstract

Hollow fiber microporous membranes have been widely used in microfiltration (MF) for water and wastewater treatment as a pressure-driven separation process. Among them, hydrophobic membranes have been also considered in membrane distillation (MD) for seawater desalination as a thermally-driven separation process. In both cases, membrane fouling is a major bottleneck limiting their widespread applications. This study focused on the control of membrane fouling in MF and MD processes by directly vibrating the modules. Experiments were carried out using a laborato-ry-scale setup in both MF and MD. Synthetic feed water containing NaCl of 35,000 mg/L and CaSO4 of 2,000 mg/L was used for fouling tests. Factors affecting flux were examined, including vibration, operation type. The frequency of vibration feed was adjusted from 100 to 200 Hz. Results showed that the effect of the vibration was more important in the MD process than in the MF process. In MD, the vibration was more effective in the inside-out operation mode than in the outside-in operation mode. The blocking of the membrane surface by the foulants occurs less severely with the vibration than without the vibration.