Li, H, Fane, TG, Coster, H & Vigneswaran, S 2003, 'Observation of deposition and removal behaviour of submicron bacteria on the membrane surface during crossflow microfiltration', Journal Of Membrane Science, vol. 217, no. 1-2, pp. 29-41.View/Download from: UTS OPUS or Publisher's site
The deposition and removal of submicron bacteria (SW8) has been examined by the direct observation through the membrane (DOTM) technique. The original DOTM was modified to incorporate fluorescence microscopy to better visualise the submicron material. The flux at which deposition commenced, the so-called critical flux, was visually identified before the transmembrane pressure indicated cake formation. After supercritical operation for about 15 min the flux was reduced to subcritical and then zero; slow cake removal was observed as distinct cylindrical rolling floc (about 50 ?m diameter) and aggregates. The extent of cake removal varied from about 90 to <5% depending on the ionic environment with low ions resulting in better removal. Cake formed over longer periods (upto 60 min) showed negligible removal. The critical fluxes of SW8 measured with DOTM increased with crossflow, but exhibited higher values than expected from their primary particle size.
Li, H, Fane, TG, Coster, H & Vigneswaran, S 2000, 'An assessment of depolorization models of cross-flow microfiltration by direct observation through membrane', Journal of Membrane Science, vol. Volume 172, no. 0, pp. 135-147.
Li, H, Fane, TG, Coster, H & Vigneswaran, S 1998, 'Direct Observation Of Particle Deposition On The Membrane Surface During Crossflow Microfiltration', Journal Of Membrane Science, vol. 149, no. 1, pp. 83-97.View/Download from: Publisher's site
In the crossflow microfiltration of particles, a deposit cake layer tends to form on the membrane and this usually controls the performance of the filtration process. This paper presents observations of particle deposition on membrane surfaces using a non-invasive, in situ, continuous direct observation through the membrane (DOTM) technique. The particles used in the experiments were typical of microfiltration processes, yeast (mean diameter 5 Î¼m) and latex beads (3, 6.4 and 12 Î¼m). The filtration tests were conducted in the imposed flux mode, so that the flux could be controlled at, below, or above the âcritical fluxâ. Below the critical flux, the particle deposition was negligible; near the critical flux the particle deposition was significant; and above the critical flux, particle layers were formed on the membrane surface. Rolling of the particles was observed during the filtration of 6.4 Î¼m latex near the critical flux whereas a flowing cake layer was observed during the filtration of 3 Î¼m latex. The particle size distribution of the deposited particles changed with the crossflow velocity, with smaller particles deposited on the membrane at higher crossflow velocity. Comparison of the normalised flux (J/ÎP) with the membrane area coverage by the particles revealed that for filtration of latex particles âflux percentage (with respect to the clean membrane)â was marginally greater than the percentage of uncovered membrane area, whereas for filtration of yeast, the âflux percentageâ was significantly less than the uncovered area percentage due to the deposition of smaller cell debris species. This paper demonstrates that DOTM is a powerful technique for the study of fundamentals of particle deposition and interactions between the particles and the membrane.
Mortari, A, Brown, NL, Geczy, CL, Coster, H, Valenzuela, S, Martin, DK & Csoregi, E 2006, 'Applications of Protein-Based Capacitive Biosensors', IEEE ICONN 2006, IEEE International Conference on Nanoscience and Nanotechnology, IEEE, Brisbane, Australia, pp. 235-238.View/Download from: UTS OPUS or Publisher's site
Three different methods of using protein-based capacitive biosensors for the detection of heavy-metal ions are presented. The metal-binding proteins SmtA, S100A12, MerP and four modified MerPs were immobilised as the biorecognition element on self-assembled monolayer-modified gold electrodes. Capacitance was measured using potential square step or electrical impedance spectroscopy. The protein-metal interaction generated changes in capacitance mainly due to a protein conformational change.