

All kinds of natural water and waste water contain impurities in the form of suspended solids in different quantities, according to site conditions. Nature and quantity of these impurities make the water unusable for drinking or for industrial applications, or even for discharge within the legally set pollution limits.
Filtration is therefore used to separate non-settleable from water and waste water by passing it through a porous medium. The most common system is filtration through a more-or-less layered bed of granular media.