This is because the filtration mechanism of diatomite determines that diatomite should be added continuously. Diatomite filtration includes three basic processes: precoating, filtering and backwashing.

The so-called pre-coating is to mix a certain amount of diatomite with water into slurry, and pump it into the filter for circulation until diatomite particles form a uniform diatomite filter cake layer on the surface of the filter element due to "bridging effect".

Filtration is a process in which the solid impurities in the raw water are intercepted and the water quality is purified when the raw water passes through the diatomite precoated membrane. In order to reduce the influence of impurities blocking the precoat, another part of diatomite should be added to the water to be filtered, which is called filter aid.

Backwashing is the process of stopping filtering and cleaning the filter membrane after diatomite is operated to a certain extent.