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Why can a gelatinous or slimy filter cake block a filter?
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Tap water filtration system.
A gelatinous or slimy filter cake blocks a filter because the particles are soft and compressible rather than firm. When these materials accumulate on a thin filter medium, they tend to "blind" the filter, meaning the pores within the cake close up and prevent the fluid from passing through.12
To prevent this stoppage, industrial processes often employ specific techniques:
- Filter aids: Porous, easily filtered solids such as diatomaceous earth or bone black are added to the slurry to improve permeability.2
- Thick filter media: Using "en masse" barriers like sand beds allows soft particles to be distributed over a larger volume, preventing the pores from closing.1
- Precoating: A layer of filter aid can be deposited on the filter surface, which is then continuously cut away to expose a fresh, non-blinded surface to the slurry.2
These methods ensure that the filtration process remains efficient despite the physical nature of the precipitate.12