Media filtration is the traditional and most common technology, yet significant knowledge and experience are required in order to provide highly efficient systems.
The removal of suspended and colloidal particles by media filtration is based on their deposition on the surface of filter grains while the water flows through a bed of these grains (filter media). The quality of the filtrate depends on the size, surface charge, and geometry of both suspended solids and filter media, as well as on the water analysis and operational parameters.
Filtering with media filters is also recognized as depth filtration. The media filters perform the filtration of water through a thick layer of graded particles. These particles can be sand, gravel or other granular materials. The filtration rate depends on the effective size of the bedding and the water velocity through the filter. The size and shape of the filter media affect the efficiency of the solids removal. Sharp, angular media form large voids and remove less fine material than rounded media of equivalent size. The media must be coarse enough to allow solids to penetrate the bed for 2-4 in. Although most suspended solids are trapped at the surface or in the first 1-2 in. of bed depth, some penetration is essential to prevent a rapid increase in pressure drop.
To solve different water problems there may be different kinds of filters media, including:
- Catalytic media for diferrization, Mn and hydrogen sulfide removal («GREENSAND», «BIRM», «FILOX», «AQUA-MANDIX», «PYROLOX» media may be used pure or mixed with hydro anthracite, sand)
- Aluminosilicate, silex and sand media for turbidity and suspended particles removal.
- Activated carbon media for taste, odor, oil, chlorine and herbicide removal.
For best solution multistage station may be applied.
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