Filter Cake Filtration And Deep Filtration

According to the mechanism of the filtration process, there are filter cake filtration and deep filtration. Filter cake filtration is also called surface filtration. Use fabrics, porous materials or membranes as filter media. The pore size of the filter medium does not have to be smaller than the size of the smallest particle. At the beginning of filtration, some small particles can enter or even pass through the pores of the medium. However, the bridging effect of the particles quickly reduces the pore size of the medium to form an effective barrier. The particles trapped on the surface of the medium form a filter residue layer called filter cake, and what passes through the filter cake layer is the purified filtrate. With the formation of the filter cake, it is the filter cake itself that really acts as the filter medium, so it is called filter cake filtration. Filter cake filtration is mainly suitable for occasions with large solid content (>1%).

In depth filtration, filter beds with thicker media layers (such as sand, diatomaceous earth, etc.) are generally used as filter media. The particles are smaller than the voids of the media and enter the media, while the long and tortuous channels are trapped and attached to the media. There is no cake formation in deep filtration, and it is mainly used to purify fluids with little solid content (<0.1%), such as water purification, flue gas dust removal, etc.