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A Solution to Waste Water...
Generally the first treatment water or waste water is subjected to is filtration using pressure sand filters. Filtration removes both the physical impurities as well as reduces BOD. A typical pressure sand filter consists of gravel of various sizes below the vessel and silica sand in the top layers. Anthracite is also used where turbudity is high as it does not let the cake formation solidify.


Silica Sand  
< It is is obtained by crushing the quartz rock to the desired size.  Due to high content of silica  is generally called silica sand. Its hardness and uniformity coffecient are makes it best material filtration. Mainly two sizes 16/32 and 8/16 are used for the filteration purpose. 16/32 size is used in top layer as it is finer than 8/16 size.
Gravel of different sizes is placed below the silica sand. Gravel provides support to the silica sand. Due to gravel filter works continuously without choking and it helps in the back washing of the filters.Round gravel is preferrable over crushed gravel as it gives better flow rate. Different sizes generally used are 2-6mm, 10-20mm, 20-40mm, with bigger size placed at the bottom followed by the smaller sizes.
Designed by: Afia Infotech