DEPOSITION OF NON-BROWNIAN PARTICLES ON COLLECTORS OF DIFFERENT GEOMETRY—APPLICATION TO DEEP BED FILTRATION OF LIQUIDS

Abstract

Theoretical results to describe the deposition process of non-Brownian particles on spherical collectors with smooth surfaces are compared with experimental data for the particle removal efficiency of deep bed filters consisting of usual granular material such as quartz sand. The remarkable discrepancies between theory and experiment lead to an improved understanding and description of the most important deposition mechanisms under realistic conditions. On this basis, two new types of deep bed filters have been developed and investigated theoretically and experimentally. The first one (the so-called membrane-stack filter) consists of a stack of membranes in which the particle deposition takes place. The usual behavior of a deep bed filter is maintained by the insertion of relatively large pores in the membranes. The second new filter type consists of a packing of synthetic spherical collectors. Such collectors, which may consist of a highly porous arrangement of fibres, are very permeable. Therefore, the deposition of particles inside the collector is possible. Both new types of filter beds lead to much higher filter efficiencies than common granular deep bed filters.

KEYWORDS:

• Non-Brownian particles
• Particle deposition
• Collector geometry
• Deep bed filtration