In many cases magnetic filter elements may be combined with mechanical filter elements in a single housing to remove both ferrous and non-ferrous contaminants in a single pass through the filter. A typical example of a high duty filter of this type is shown in Figure 3.84. More simply, the same effect may be provided […]
The design of a permanent magnet filter suitable for use in troughs or settling tanks is shown in Figure 3.82. A number of core magnets are arranged side-by-side in a nonmagnetic housing and effectively connected in parallel by the special pole pieces. The filter cage then consists of a series of strips on either side […]
Just like the pipeline strainers described in Section 3B, special forms of magnetic filters have been developed specifically for installation in pipelines, an easily cleaned version being illustrated in Figure 3.81. Here, the central core of the filter element comprises a permanent magnet enclosed in a non-magnetic cover. Surrounding this cover are a number of mild […]
Magnetic filters are specialized straining systems for the removal of iron and other ferro-magnetic particles from liquid suspensions and flows of solid particles. They are in effect simple magnets or magnetic assemblies that, when suitably located in a fluid system, can attract and retain ferrous metal, nickel and cobalt particles that may be present in […]
A significant development in membrane technology has been the membrane bioreactor. This is a combination of a bioreactor (i.e. a reactor in which a biological process occurs, most commonly the secondary or activated sludge stage of a wastewater treatment system) with a membrane filter, operating in through-flow or crossflow . This has become a major […]
Factors that have a profound influence on the structure or morphology of a particular membrane are the nature of the process by which it is manufactured and the form of the raw material used. The main manufacturing processes are: ● sintering of fine graded particles ● solvent casting or phase inversion, involving the stage-wise evaporation […]
The build-up of a fouling layer on the surface of a membrane is one of the most ser ious problems in membrane processes. The term ‘ fouling, ’ rather than the more familiar ‘ filter cake,’ arose from the origins of membrane processes in molecular separations, where macromolecular proteins would separate on to the membrane […]
Originally implying a thin, microporous or semi-permeable plastic sheet, the term ‘ membrane ’ is now applied to any filter medium that is capable of removing particles below 0.1m. The membrane represents probably the fastest growing part of the filtration media market (especially if ceramic membranes for hot gas filtration are included). Modern membrane technology […]
The cross-flow principle ( Figure 3.76) began with the hollow fibres used in reverse osmosis, and has expanded to become one of the most important components of the filtration industry. In order to keep the surface free of deposit, high-shear conditions are employed, and these can be created either by a high suspension velocity across […]
There are two distinct modes of liquid filtration. In one, the filter medium sits across the fluid flow channel, so that all of the liquid must pass through the medium, leaving any separated solids to be held in or on the medium. This is called through-flow or dead-end filtration, and it separates most or all […]
