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The principle of sand filter


The principle of sand tank filtration Sand tanks generally place a certain scale of quartz sand. The size and specifications of quartz sand are different within a certain range. In the sand tank, the quartz sand is arranged from top to bottom, from small to large. During normal filtration , water enters from the upper layer of sand and comes out from the lower layer. When water flows through the filter layer from above, part of the solid suspended matter in the water enters the tiny holes formed by the upper filter material and is trapped by the surface layer of the filter material due to adsorption and mechanical retention. At the same time, the suspended matter between these trapped Overlapping and bridging occurs again, as if a thin film is formed on the surface of the filter layer, which continues to filter the suspended matter in the water, which is the so-called membrane filtration of the surface layer of the filter material. This filtering effect is not only on the surface of the filter layer, but also has this interception effect when water enters the middle filter layer. In order to distinguish it from the filtration of the surface layer, this effect is called osmotic filtration.

In addition, because the sand particles are closely arranged with each other, when the suspended particles in the water flow through the tortuous channels in the sand layer, there will be more opportunities and time to collide and contact with the surface of the filter material. The suspended solids in the sand layer bond with the flocs on the particle surface of the sand layer to form a contact coagulation process. To sum up, the filter sand tank is to further purify the water through the process of membrane filtration, osmosis filtration and contact filtration. What is the role of circulating filtration in the process of purifying swimming pool water? After coagulation, sedimentation and suction of pool water, some of the larger solid particles or impurities that are easy to settle have been removed. To further purify the water, it is necessary to use The method of filtration is to make the water pass through the sand filter layer, and the fine particulate impurities in the water are intercepted, so that the water is further purified and the turbidity of the water is further reduced.

Filtration can also remove a large amount of organic substances, bacteria, viruses, etc. in water with the reduction of turbidity, and create good conditions for disinfection after filtration, because bacteria in water lose the protection and dependence of turbidity and present a naked form It is beneficial for sterilization. Why should the filter sand tank be backwashed? What should be paid attention to in backwashing? During the circulation process of the filter sand tank, because the sand layer intercepts the suspended solids in the water, when the suspended solids reach a certain amount, it will affect the filtration speed and quality, especially Adding coagulant before the sand cylinder requires mastering the recoil time. Backwashing is used to remove suspended solids trapped in the sand tank to restore the filter capacity of the sand tank. Backwashing must master the speed and time of backwashing. If quartz sand is used as the filter material, the backwashing intensity should not be lower than 15L/( S.m2), Backwashing time 5~6mim or observe backwashing Poolking is the best swimming pool equipment manufacturer and supplier in China. Poolking exists to provide the highest quality swimming pool equipment while offering competitive pricing..

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