Effect of Ultrasound on Fouling of Ultrafiltration Membrane
Date Issued
2008
Date
2008
Author(s)
Yang, Hsiu-Lan
Abstract
The ultrasound assisted membrane filtration process can effectively remove fouling of ultrafiltration membrane filtration caused by dissolved organic matters product. In this study, low frequency (20 kHz) and high frequency (40 kHz) was applied for removal of fouling substances, cavitation phenomenon of ultrasound to remove irreversible fouling with the combination of NaOH to achieve better removal efficiency. By observing the gel filtration chromatography (GFC) with different ultrasound frequency and time, and the molecular size of humic acid, the longer time of ultrasound, coagulation phenomenon is more domination. Therefore, the degradation rate if better under high frequency of ultrasound, the shorter of the wavelength, the compress detention time is shorter with more dominant of cavitation phenomenon, and more OH radical produced, the humic acid can completely degrade. The ultrasound assisted membrane filtration process with different pore diameter under absent of ultrasound cleaning、low frequency and high frequency of cleaning, with flux recovery of 37%、90%、82% and 23%、80%、68% respectively. Small pore has better result than large pore while low frequency of ultrasound has higher cleaning efficiency. This is because fouling more likely to happen in large pore and it is hard to clean the inner part. Low frequency will have longer wavelength and compress detention timer, this will removed fouling of membrane surface. The combination of NaOH to assisted cleaning at low and high frequency ultrasound of cleaning, the flux recovery can enhanced up to 99%、94% and 98%、92%. The additional NaOH can make OH radical oxidized and hydrolysis the organic fouling. The data results suggest that cavitation associated with NaOH may produce more bubbles collapse phenomena, which can easily ensues fragmentation or abrasion on surface fouling.
Subjects
Dissolved organic matters
Ultrafiltration membrane
Cavitation phenomenon、Irreversible fouling
Gel filtration chromatography
Flux recovery
Type
thesis
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