Sand filter is also called sand cylinder filter, sand cylinder, sand filter, sand filter equipment, sand filter device, which is also called quartz sand filter. The sand filter is generally used as the pretreatment of water purification equipment. It is mainly used to intercept and adsorb sediment, colloid, metal ions and organic matters. Because of its pollution-free, low price and low operating cost, it is widely used in agricultural irrigation, chemical industry, petroleum, metallurgy, industry and mining and other industries. Common filters are made of stainless steel 304 and carbon steel.

The sand filter is simple in structure, convenient in operation and backwashing. Its operation is mainly to change the direction of water by adjusting four valves. During operation, the water enters from the top to the bottom and backwashes from the bottom to the top. Then, the sewage from backwashing is discharged through the drain valve, and then the water is washed until the water is clear and clean. When filling the quartz sand, attention should be paid to: the specification of the quartz sand in the sewage intercepting layer is 0.5-1.0mm, the height is more than 700mm, and there are two supporting layers below, The filling heights of 1-2mm and 2-3mm are 150-200mm and 150-200mm respectively. The sewage interception capacity of untreated water is 0.5-1.0 Kg/m3, that of lime treated water is 1.5-2.0 Kg/m3, and that of coagulated water is 2.5-3.0 Kg/m3.