In Situ Characterization of Membrane Fouling and Cleaning Using a Multiphoton Microscope

In Situ Characterization of Membrane Fouling and Cleaning Using a Multiphoton Microscope 

Robert Field, David Hughes, Zhanfeng Cui, and Uday Tirlapur 

Optical techniques are principally used to visualize the membrane surface and the deposits thereon. The resolution of these images depends upon the illumination source. Systems using what might be termed standard visible light based microscopy are capable of resolutions of 0.5 pm [1]. This makes them suitable for the imaging of filtration cakes of micron-sized particles. To achieve higher resolutions 

Monitorir and Visualizing Membrane-Based Processes Edited by Carme Giiell, Montserrat Ferrando, and Francisco Lopez Copyright 2009 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-32006-6 

Early systems based on visible light used high-zoom video cameras positioned to view the membrane from the side. The ability to continuously record, in real time, activity at the membrane surface made this type of system ideal for in situ imaging of cake deposition, provided the particles were sufficiently large. A 15 x zoom video camera was used to record in situ particle motion of large polyethylene particles (125-180 pm) dose to a stainless steel mesh filter 3]. The particles in this study were much larger than those typically found in microfiltration applications. Another study [4] used a similar system to record the deposition of more realistic caldte (2.6 pm, 25 pm) and anatase (0.5 pm) particles. Individual particles could not be resolved and only a cake thickness was quoted. In both studies the cakes thicknesses were in the millimeter range. 

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