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Several Types of Clarifying Filtration

In previous post, I shared several types of filtration methods and more about cake filters. In this post, I want to share to you several types of clarifying filtration.

Read also: Introduction to Filtration

Read also: Many Types of Cake Filters

The main objective of clarifying filters is to remove small amounts of solids or liquid droplets from either liquids or gases. The liquid may be drinking water, wine, beer, oil, etc., and it is usually the liquid which is the valuable product.

In clarifying filters, the particles are trapped inside the filter medium or on its surfaces. Surface forces catch the particles and immobilize them on the surfaces or within the flow channels.

In general, clarifying filtration are categorized into liquid clarification and gas cleaning.

Liquid Clarification

Clarifying filters for liquids are especially important in polishing materials. Clarifying filters include gravity-bed filters for water treatment and various disk and plate presses and cartridge clarifiers. The feed to such units generally contains less than 0.1% solids. Some cake filters, especially tank filters and continuous precoat filters, are used extensively for clarification.

Gas Cleaning

Filters for gas cleaning include pad filters for atmospheric dust and granular beds and bag filters for process dusts. Air is cleaned by passing it through pads of cellulose pulp, cotton, felt, glass fiber, or metal screening. For light duty the pads are disposable, but in large-scale gas cleaning they are frequently rinsed and recoated with oil.


McCabe, Warren L, and Julian C. Smith, “Unit Operations of Chemical Engineering Seventh Edition”, McGraw-Hill, 2005.