Improved ultrasonic cleaning of membranes with tandem frequency excitation

In water purification membrane fouling is the most common problem that decresases efficiency in the purification process. In this work we propose a simple method to remove the particles deposited on the membrane surface by applying two different ultrasound frequencies in tandem. First a high ultraso...

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Bibliographic Details
Published in:Journal of membrane science 2012-10, Vol.415-416, p.776-783
Main Authors: Gonzalez-Avila, Silvestre Roberto, Prabowo, Firdaus, Kumar, Anshuman, Ohl, Claus-Dieter
Format: Article
Language:English
Subjects:
artificial membranes
bubbles
Chemistry
cleaning
Colloidal state and disperse state
Exact sciences and technology
fouling
General and physical chemistry
High-speed video imaging
Membrane-fouling
Membranes
purification methods
ultrasonics
Ultrasound-cleaning
water purification
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Summary:In water purification membrane fouling is the most common problem that decresases efficiency in the purification process. In this work we propose a simple method to remove the particles deposited on the membrane surface by applying two different ultrasound frequencies in tandem. First a high ultrasound frequency, here 220kHz, is used to create microscopic bubbles that are immediately after excited with a lower ultrasound frequency, e.g., 28kHz. High speed video of the bare membrane shows the higher number of bubbles after the application of the high ultrasound frequency, as opposed to applying only a low ultrasound frequency. The method is then evaluated by recording the flux delivered and the transmembrane pressure (TMP) in this small scale experiment. The results show that after the application of the tandem frequency the transmembrane pressure is restored to the value of the non fouled membrane. ► Ultrasonic cleaning is caused by oscillating bubbles near to the membrane surface. ► Small bubbles can be formed on the membrane surface using a high-frequency ultrasound. ► A quick switch to a low-frequency ultrasound converts these bubbles into cleaning bubbles. ► This tandem frequency ultrasound field is studied in detail with high-speed photography. ► The trans-membrane pressure of the clean membrane is recovered.
ISSN:0376-7388
1873-3123
DOI:10.1016/j.memsci.2012.05.069