Cake Filtration

When liquids contain high solid loads, cake filtration is often used as a physical filtration technology. The liquid passes through the filter medium while the solids form a layer on its surface. During the filtration cycle, this layer retains other particles and becomes thicker, creating the ‘filter cake’.

Once particles start to bridge and build on the filter medium, they become the barrier for further particle retention. The filter medium becomes the carrier of the actual filter – the filter cake – and cake filtration occurs through this.

If the solids present can’t form the first initial layers, then a filter aid can be used to precoat the filter. Filter aids can also be added during filtration to maintain an open structure, ensuring the filter cake remains permeable and that a suitable flux and cake thickness is reached. Typical filter aids include cellulose, diatomaceous earth (Kieselguhr) and perlite.