why watertreatment with pressure sand filter?  

by Pool Builders on 12-01-2010 in Articles

Sand filter - Sand filters are used for water purification. There are three main types; rapid (gravity) sand filters upflow sand filters slow sand filter s All three methods are used extensively in the water industry throughout the world.

If the pressure in the filter drops then this indicates that the filter is not getting sufficient pool water through the circulation system. This could be due to blocked skimmers and sumps inside the pool, restricted suction pipes in the balance tank, or the suction pipes from the pool are blocked off or restricted.
pressure sand filter consists of a pressure vessel-this could be either vertical or horizontal-fitted with a set of frontal pipe work and valves, graded silica quartz sand supported by layers of graded under bed consisting of pebbles and gravels, a top distributor to distribute the incoming water uniformly throughout the cross section of the filter, and an under drain system to collect filtered water.

Sand dunes are not only made of sand but also of water. You don't have to dig very far to see the moisture in the sand. One of the unique features of sand is that it helps filter water that passes through it.

Go out to the sand and have the students dig into the sand and describe what they find. Talk about why they think it is cool and wet. Ask the students where they think the water came from and where they think it goes. Doing Castles in the Sand prior to this activity helps students understand how sand and water work together through a process called capillary action.

Raw water flows down wards through the filter bed and as the suspended matter- which has usually been treated by addition of a coagulant like alum- is retained on the sand surface and between the sand grains immediately below the surface. There is steady rise in the loss of head as the filter process continues and the flow reduces once the Pressure sand filter drop across the filter is excessive.

The Pressure sand filter is now taken out of service and cleaning of the filter is effected by flow reversal. To assist in cleaning the bed, the backwash operation is often preceded by air agitation through the under drain system. The process of air scouring agitates the sand with a scrubbing action, which loosens the intercepted particles. The filter is now ready to be put back into service.

Picture Low Flow PSF (FRP Vessel) and High flow custom Vessel (MS Vessel)

Sand filter - Sand filters are used for water purification. There are three main types; All three methods are used extensively in the water industry throughout the world. The first two require the use of flocculant chemicals to work effectively whilst slow sand filters can produce very high quality water free..

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