1-FILTERATION PROCESS
The effluent obtained after coagulation and sedimentation does not satisfy the drinking water standared and is not safe or palatable so it requires further treatment.if water is allowed to pass through a bed of fine granular matrial ,the effluent obtaind is clear and sparking with negligble turbidity. this process is known as filtration which helps also in removing bacteria,colour,iron,and manganese from water.
1- FILTRATION MEDIA;
a) SAND: the sand used in filters should be free from dirt,hard resistance and preferably of pure silca .it should be tested so that it must not lose more than5% of its weight after being placed in hydrochloric acid for 24 hrs. the size of sand is specified by its effective size which is the sieve size in milimeters thatpermits a max. of 10% of the sand by weight to pass .the size of sand used in compact unit lies between 0.7mm-1.25mm and the thickness of its layer of about 40-50 cm.
b) GRAVEL: the gravel used in filters for supporting the sand and permits the filterd water to move freely to the underdrains and also allows wash water to move uniformaly upward.it shoud be hard .rounded ,durable,free fromfats,dirts.....etc.it should also be of effective size of 2m to 3.2mm and of weight of about 1600kg/m3.the thickness of the gravel layer is about 20 cm.
2-FILTRATION UNDERDRAINES:
the underdrains which is simply an arrangement below the layer of gravel on the floor to collect the filterd water to convey it to the pipe leading to the treated water storage tank,are asystemof plastic nozzles supported on a thick plate(of15mm thickness) in a uniform distribution. the typical configuration of such nozzles ara that they are cheap.easy in mounting,giving a uniform discharge and permit a uniform distribution of back wash water and air to the filtration media.
3- FILTRATION VESSLS:
the vessls used in the compact unit are welded construction designed and manufactured on normal boiler and pressure vessels code to handle working pressure up to 1.5 times the maximum allowable pressure as calculated for the weakest element of the vessel.water normally enters the vessels at 1bar pressure which is developed by high lift pumps at sedimentation clear wel.
each vessel is equipped with 3manholes (one at the bottom deshend and secon at the top deshend and the third on its barrel) for easier changing and repparing of the filter media and its underdrains.
The effluent obtained after coagulation and sedimentation does not satisfy the drinking water standared and is not safe or palatable so it requires further treatment.if water is allowed to pass through a bed of fine granular matrial ,the effluent obtaind is clear and sparking with negligble turbidity. this process is known as filtration which helps also in removing bacteria,colour,iron,and manganese from water.
1- FILTRATION MEDIA;
a) SAND: the sand used in filters should be free from dirt,hard resistance and preferably of pure silca .it should be tested so that it must not lose more than5% of its weight after being placed in hydrochloric acid for 24 hrs. the size of sand is specified by its effective size which is the sieve size in milimeters thatpermits a max. of 10% of the sand by weight to pass .the size of sand used in compact unit lies between 0.7mm-1.25mm and the thickness of its layer of about 40-50 cm.
b) GRAVEL: the gravel used in filters for supporting the sand and permits the filterd water to move freely to the underdrains and also allows wash water to move uniformaly upward.it shoud be hard .rounded ,durable,free fromfats,dirts.....etc.it should also be of effective size of 2m to 3.2mm and of weight of about 1600kg/m3.the thickness of the gravel layer is about 20 cm.
2-FILTRATION UNDERDRAINES:
the underdrains which is simply an arrangement below the layer of gravel on the floor to collect the filterd water to convey it to the pipe leading to the treated water storage tank,are asystemof plastic nozzles supported on a thick plate(of15mm thickness) in a uniform distribution. the typical configuration of such nozzles ara that they are cheap.easy in mounting,giving a uniform discharge and permit a uniform distribution of back wash water and air to the filtration media.
3- FILTRATION VESSLS:
the vessls used in the compact unit are welded construction designed and manufactured on normal boiler and pressure vessels code to handle working pressure up to 1.5 times the maximum allowable pressure as calculated for the weakest element of the vessel.water normally enters the vessels at 1bar pressure which is developed by high lift pumps at sedimentation clear wel.
each vessel is equipped with 3manholes (one at the bottom deshend and secon at the top deshend and the third on its barrel) for easier changing and repparing of the filter media and its underdrains.
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