These are filters used for filtering fine particles after pre-filters and as secondary and final filters before absolute filters. It is generally preferred for filtration of particles with particle size in the range of 1-10 µm.
Multimedia water filters commonly employ a tri-layer media system for effective filtration: anthracite, sand, and garnet. The selection of these media in multimedia filters is based on their varying densities, which contribute to their filtration capabilities.
The first layer of filter media entraps and holds larger sized particles allowing smaller particles to be removed in subsequent media layers. The final media layer “polishes” the water removing suspended solids down to 1 micron in size and smaller.
Trapping sediment and particulates throughout the entire depth of the filter bed, allows multi-media water filters to operate for much longer periods of time than conventional sand filters. The process of multimedia filtration produces high quality, filtered water at much faster flow rates than traditional sand filtration.