The usual pretreatment system is composed as follows: coarse filtration (~80 microns) to remove large particles, adding oxidants such as sodium hypochlorite, then 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 accidental large particles. Water sources containing more suspended particulate matter usually require a higher degree of pretreatment to meet the specified water inflow requirements; water sources with high hardness content are recommended to use softening or adding acid and scale inhibitors. High water sources also require the use of activated carbon or anti-fouling membrane elements.
