Filter Media

Filtration is under the action of driving force, the fluid in the suspension (or dust-containing gas) on one side flows to the other side through the pores of the porous medium. The particles are retained, so as to realize the separation operation process of the fluid and the particles. The filtered suspension is also called the filter slurry, the particle layer retained during filtration is called the filter cake, and the filtered clear liquid is called the filtrate.

The filter medium is a porous medium that allows fluid to pass through and particles are retained. No matter what kind of filtration method is used, the filter medium is always necessary, so the process medium is one of the elements of the filtration operation.

The common requirements of multiple filter media are porosity, stable physical and chemical properties, durability and reusability. There are many materials that can be used as filter media, which can be mainly divided into:

⑴Fabric medium

Fabric is a very commonly used filter medium. Industrially known as filter cloth (net), it is composed of natural fiber, glass fiber, synthetic fiber or metal wire. The smallest particles that can be retained depend on the size of the mesh, generally in the range of a few to tens of microns.

⑵Porous materials

Various porous solid materials made into sheets, plates or tubes, such as bisque, sintered metal and glass, porous plastics, and filtered and compressed felt and cotton. This kind of medium is thicker, has fine pores, and can retain tiny particles of 1~3μm.

⑶ Solid particle bed

The bed formed by the accumulation of solid particles such as sand and charcoal is called a filter bed. Used as a filter medium to clarify liquids containing a small amount of suspended solids.

⑷Porous membrane

The polymer film synthesized by a special process, the most common are cellulose acetate film and polyamide film. Membrane filtration is ultrafiltration, which can separate 5nm particles.