... sand filter, activated carbon (AC) filter and polypropylene fiber (PP) filter. As to high hardness of the raw water, the ... filled with softening resin. PP filters can be efficient in removing above 5 µm mechanical particles impurities in the raw water,rust and ... , iron, organic matter, pesticides, manganese, beacteria, virus etc. pollutants in the water. Softening resin can remove the most of the ...