Unravelling transport and deposition mechanisms of virus-like colloids during depth filtration

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Membrane-based depth filtration is widely applied e.g. in virus filtration and contaminant removal. The performance of depth filtration is commonly limited by the trade-off between permeability and retention. A fundamental understanding of colloid and particle transport as well as their deposition phenomena in the depth of the porous medium is of fundamental interest. A variety of studies exist describing the performance of depth filtration by either macroscopic measurable breakthrough curves and flux-pressure diagrams or by the microscopic analysis of the membrane after filtration. Transport and deposition phenomena are hypothesized, based on these crude macroscopic measurements. However, the fundamental transport and deposition phenomena still lack a microscopic experimental analysis and validation.Many phenomena such as the role of shape and deformability of the colloid and particles, their resuspension, and the influence of surface characteristics are only poorly understood. The inability to monitor non-invasively in real-time these phenomena inside the porous media represents the key limitation of why the transport and deposition phenomena still lack microscopic understanding so far.This project will in-situ characterize the microscopic transport and deposition phenomena inside porous media by (a) micro-engineering of both the colloids as well as the porous filter structures integrated with (b) sophisticated visualization methods such as micro Particle Velocimetry µPIV, Fluorescent Lifetime Imaging (FLIM), and confocal microscopy. The methodology enables us to deconvolute the complex interplay between transport and deposition phenomena. Their experimental observation allows a fundamental understanding of the capture process during depth filtration and establishes a classification of microscopic events that can be related to real-life membrane filter performance. Complemented with our ongoing simulation activities, this knowledge will be a prerequisite to close the gap between the microscopic colloidal domain and the macroscopic filtration world.