Filtration

FILTRATION

Filtration consists of passing the water through some porous material to remove the suspended impurities. Filtration is one of the oldest and simplest procedures known to man for removing suspended matter from water and other fluids.It is a common misconception that filtration removes suspended solids by a simple straining process whereby particles too large to pass through openings in the filter media are retained on the media,

The mechanism involved in removing suspended solids by filtration is very complex. While straining is important at the filter media surface, most solid removal in deep granular filters occurs within the filter bed.

Before filtering, water is normally pretreated by passing it through sedimentation basins or holding tanks. Flocculation and sedimentation in the pore spaces between filter media particles are an important removal mechanism as well as absorption of particles onto the filter media surfaces.

Additional straining between media particles within the filter also contributes to overall solids removal. This process removes heavier suspended solids that may cause rapid clogging of the filter.

This water is brought onto the filters as the next step in the purification process. This water contains very finely divided suspended matter such as minute particles of floc, clay, and mud that have not settled, and bacteria and microscopic organisms that have not been removed by sedimentation.

The purpose of the filter is to remove this suspended matter and give the water a clear, sparkling, attractive appearance.

Water must be clean before any type of disinfection is used. Bacteria, viruses, cysts and other pathogens will "hide" behind dirt particles. Treating water is a hierarchy of needs approach and certain conditions must be solved or removed before other conditions can be solved.

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