Full Description

Recent research on colloidal fouling has taken into account the deposition ofparticles and buildup of cakes formed along membrane surfaces and their effect onflux. Nevertheless, most of these studies have relied on indirect methods ofverification, such as matching experimentally measured and simulated flux declinecurves or gross mass balances on colloidal material. The objective of this workis to develop a direct visualization technique to monitor colloidal dynamics inthe region of membrane surfaces during micro- and ultrafiltration. Fluorescencemicroscopy and continuous video recording are used to monitor particle motions inthe concentration boundary layer and deposition on the membrane surface. The topof the visualization cell is transparent, and illumination and visualization arefrom above the membrane surface (retentate side illumination/visualization). Thisarrangement allows us to work with virtually any flat sheet membrane material. Inthis presentation, the visualization system is used to better understand theeffect of transmembrane pressure on deposition of particles at the surface of apolycarbonate microfiltration membrane. The filtration system is also equipped toregulate and monitor system pressures and flows, hence the flux decline can berelated qualitatively to the deposition history. Results show that fluxdecline and the kinetics of cake formation at constant crossflow velocity are afunction of the transmembrane pressure. Real-time visualization techniques shouldbe of great value in future studies of pretreatment, biofouling and the effect ofcleaning and cleaning frequency on cake buildup and removal from membranesurfaces. Includes 24 references, figures.

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Edition: Vol. - No. Published: 05/01/2001 Number of Pages: 16File Size: 1 file , 5.4 MB