Mitigation of Fouling on Hollow Fibre Membrane Using Ultrasonic Transducer

Abstract

Ultrasound based on-line cleaning for hollow fiber (HF) membrane filtration of synthetic wastewater was studied. An ultrasonic transducer was submerged into a filtration system in order to get an efficient cleaning of HF membranes in fouling conditions. An ultrafiltration (UF) HF membrane with the pore size at 10,000 NMWC is employed to purify waste water. The focus of this study is on the effects of temperature, ultrasonic frequency, ultrasonic power intensity and caviation micro-bubbles as well as the transmembrane pressure (TMP) performance. Experimental evidence reveals that the permeate flux increased with the application of ultrasound after fouling by sullage solution for one hour. The micro-bubble size measured by laser PDA system shows a decreased tendency with the increase of ultrasonic frequencies, and larger micro-bubbles have greater contribution to the increase of permeate flux. Results futher shows that the permeate flux measured with lower ultrasonic frequency or higher power intensity maintained higher value in general as feeding sullage water and maintain a higher risk to extend membrane pore size. In addition, the rise of the temperature around filtration system has less impact on permeate flow rate in online ultrasound system when the temperature of feed solution maintained constant.