The usual pretreatment system is composed as follows: coarse filtration (~80 microns) to remove large particles, adding oxidants such as sodium hypochlorite, followed by precision filtration through a multi-media filter or clarifier, and then adding sodium bisulfite to reduce residual chlorine and other oxidants, Finally, install the security filter before the inlet of the high pressure pump.
The role of the security filter is as the name implies, it is the ultimate insurance measure to prevent the damage of the impeller and membrane elements of the high-pressure pump by occasional large particles. Water sources containing high levels of suspended particles usually require a higher degree of pretreatment to meet the specified water influent requirements; water sources with high hardness content are recommended to use softening or adding acid and scale inhibitors. For water sources with high microbial and organic content, activated carbon or anti-pollution membrane elements are also required.
