(PAM) polyacrylamide is a general term for acrylamide homopolymer or polymers copolymerized with other monomers. (PAM) polyacrylamide is one of the most widely used varieties of water-soluble polymers. (PAM) polyacrylamide is widely used in oil extraction, papermaking, water treatment, textiles, medicine, agriculture and other industries. According to statistics, 37% of the total global (PAM) polyacrylamide production is used for wastewater treatment, 27% for the oil industry, and 18% for the paper industry.
Technical process of PAM precipitation:
Precipitation is the generation of substances insoluble in the solution of the reactants during a chemical reaction. From the literal meaning, it means precipitation and removal under the action of gravity. Suspended matter in sewage, so this is a physical process, simple and easy, with good effect, and is one of the important technologies for sewage treatment.
According to the nature and concentration of suspended matter and the flocculation performance of polyacrylamide, precipitation can be divided into: natural precipitation, flocculation precipitation, and regional precipitation. The concentration of suspended particles in regional sedimentation is high (above 5000mg/L). The sedimentation of particles is affected by other particles around them. The relative positions between particles remain unchanged, forming a whole sinking together, and there is a clear mud-water interface between the clarified water. Regional sedimentation occurs in both secondary sedimentation tanks and sludge thickening tanks.
The concentration of suspended solids in wastewater is not high, and it does not have the property of coagulation. During the sedimentation process, the solid particles do not change their shape or adhere to each other, and each completes the sedimentation process independently. (Initial sedimentation in grit chambers and primary sedimentation tanks) Compression sedimentation occurs in the sedimentation process of high-concentration suspended particles. Due to the high concentration of suspended particles, the particles have been squeezed into a mass structure, contacting and supporting each other. The water between the lower particles is squeezed out under the gravity of the upper particles, so that the sludge is concentrated. Compression sedimentation occurs in the polyacrylamide concentration process in the sludge hopper of the secondary sedimentation tank and the sludge concentration process in the thickening tank. Free sedimentation occurs when the concentration of suspended solids in water is not high. The suspended solids do not interfere with each other during the sedimentation process. The particles precipitate separately, and the precipitation trajectory of the particles is straight. During the entire sedimentation process, the physical properties of the particles, such as shape, size and specific gravity, do not change. The sedimentation of such particles in the grit chamber is free sedimentation.
Flocculation sedimentation is the process of flocculation and sedimentation of particles in water. After adding coagulants to the water, the colloids and dispersed particles of the suspended matter form flocs under the interaction of molecular forces, and during the sedimentation process, they collide and condense with each other, their size and mass continue to increase, and the sedimentation rate continues to increase. The removal rate of suspended matter depends not only on the sedimentation rate, but also on the sedimentation depth. The alum flowers formed after adding coagulants to the surface water, the organic suspended matter in domestic sewage, and the activated sludge will all show flocculation and sedimentation during the sedimentation process.
