1, coarse filtration: refers to mechanical filtration, removal of suspended solids in water, colloid, turbidity, chroma, odor, etc. The main filtration methods are clarifier, fast filter, sand filter, sand filter, multi-media filter, activated carbon filter, disc filter, high efficiency fiber filter and so on.

2, fine filtration: filter membrane made of special materials, high filtration accuracy. Common for microfiltration membrane and filter element filtration.

3, over filtration: is a membrane filtration, removal of macromolecules and colloid, bacteria, etc. High filtration accuracy, common is ultrafiltration membrane.

4, reverse osmosis: reverse osmosis referred to as RO, its principle is raw water under the action of high pressure through the reverse osmosis membrane, the solvent in the water from high concentration to low concentration diffusion to achieve the purpose of separation, purification, concentration, because it is opposite to the nature of the osmosis direction.

5, ion exchange: all kinds of inorganic salts in water ionization generated Yang, anion, through the hydrogen ion exchanger layer, the cation in the water was replaced by hydrogen ion, namely, the principle of removing salt bed; When passing through the OH- type ion exchanger layer, the anions in water are replaced by OH- ions, which is the principle of Yin bed desalting.

Mixed bed is an ion exchange device in which positive anion exchange resin and anion exchange resin are mixed and filled in the same exchange column in a certain proportion.

6, EDI: electrodialysis and ion exchange combined with the new process of salt removal, take the electrodialysis and mixing bed ion exchange, the use of ion exchange to do in-depth treatment, no reagent regeneration, with ionization to produce H+ and OH-, to achieve the purpose of resin regeneration.