The Role and Position of Sand Filters in the Water Purification Process of Waterworks

　　As an important part of the watersupply system, the waterworks plays a crucial role in converting urban wastewater or natural water into water quality that meets national drinking water standards through a series of purification treatments. In this process, the sand filter plays a vital role, playing a key role in the water purification process and occupying an important position.

I. The Function of Sand Filters

The main function of the sand filter is to remove suspended particles, colloids, and organic matter from the water through sand layer filtration, improving the cleanliness of water quality. Its filtering principle is based on the intercepting and adsorbing effect of the sand layer on particles in the water, which can effectively remove suspended matter, colloids, bacteria, viruses, organic matter, and some inorganic matter. The sand filter removes suspended matter from the water through physical filtration, reducing the content of suspended matter in the water to achieve the purpose of purifying water quality. At the same time, the sand filter also has a certain disinfection effect, which can adsorb microorganisms in the water through the intercepting effect of the filter layer, achieving preliminary disinfection effects.

II. The Position of Sand Filters in the Water Purification Process

The position of the sand filter in the water purification process is generally in the pretreatment stage. In the water supply process of the waterworks, water usually goes through treatment steps such as coagulation, sedimentation, filtration, and disinfection. Among them, coagulation and sedimentation are pretreatment steps to remove large particle impurities from the water, while filtration and disinfection are deep treatment steps to remove small particle impurities and microorganisms. After coagulation and sedimentation, water enters the sand filter for filtration treatment. The sand filter is usually located after the sedimentation pool and before the filter pool, and its main function is to further remove fine suspended particles, colloids, and organic matter from the water to improve the cleanliness of the water. After filtration, water usually undergoes disinfection treatment to ensure water quality safety.

　　III. Types and Selection of Sand Filters

According to the different filtering media, sand filters can be divided into quartz sand filters, smokeless coal filters, activated carbon filters, and so on. Among them, the quartz sand filter is the most common type, which has the advantages of high filtration efficiency, long service life, and simple operation. When selecting a sand filter, it is necessary to consider factors such as the water quality to be treated, the treatment capacity, and the operating cost, and choose the appropriate type and specification of the sand filter.

In summary, the sand filter plays an important role in the water purification process of waterworks, removing suspended particles, colloids, and organic matter from the water through physical filtration methods to improve the cleanliness of water quality. The sand filter is usually located in the pretreatment stage of the waterworks, after coagulation and sedimentation and before the filter pool. When selecting a sand filter, it is necessary to consider factors such as the water quality to be treated, the treatment capacity, and the operating cost, and choose the appropriate type and specification of the sand filter.