A multi-media filter (also known as a mechanical filter) is a typical multi-media filter with layered anthracite, sand, finely crushed garnet or other materials as the bed. The top layer of the bed consists of the lightest and coarsest grade material, while the heaviest and finest grade material is placed at the bottom of the bed. The principle is filtration by depth - larger particles in the water are removed in the top layer and smaller particles are removed deeper in the filter media.So that the water quality reaches the standard after coarse filtration. This kind of filter is pressure type, and its principle is that when the raw water passes through the filter material from top to bottom, the suspended matter in the water is intercepted by the surface of the filter layer due to adsorption and mechanical resistance; The sand particles in the material layer are arranged more tightly, so that the particles in the water have more opportunities to collide with the sand particles, so the flocs, suspended solids and the surface of the sand particles in the water adhere to each other, and the impurities in the water are trapped in the filter material layer, thus obtaining clarification. water quality. The filtered effluent suspension can be below 5 mg/L.

Multi-media filter replacement method Operation steps Operation method

1 Drain Drain the accumulated water inside the multi-media filter

2 Unloading Open the discharge port of the multi-media filter, feed a small amount of water from the backwash port, and flush out the packing.

3 Cleaning Drain the accumulated water in the multi-media filter, open the upper manhole, enter the filter, and clean the remaining filter material out of the filter

4 Cleaning Clean the inside of the multimedia filter with a rag

5 Filling the filter material Close the discharge port, fill up the filling filter material according to the regulations, first load the quartz sand, and then level off after loading, and then load the anthracite

6 Close the filter to check that the filling height of the filter material meets the requirements, and close the upper manhole

7 Rinse the filter material Rinse the filter material according to the filter backwashing steps until the drainage turbidity is less than 1 degree

Filter material: (1) Anthracite (upper layer): particle size: 0.8-1.2mm; thickness: 400mm

(2) Quartz sand (lower layer): particle size: 0.4-0.65mm; thickness: 800mm