Urban sewage treatment generally aims to remove BOD (biochemical oxygen demand) substances. In large sewage treatment plants, primary sewage treatment centered on sedimentation and secondary sewage treatment centered on biological treatment are mostly used. Sometimes in order to remove nitrogen, phosphorus and other substances, tertiary sewage treatment is carried out after biological treatment. The future development of urban sewage treatment plants will not only increase the number, but also gradually increase the proportion of secondary treatment plants, and start to build tertiary treatment plants. Polyacrylamide for domestic sewage treatment
In the application of polyacrylamide in water treatment in developed countries, the United States accounts for 63% of the total polyacrylamide consumption, Western Europe accounts for 35%, and Japan accounts for 49%. The consumption structure of polyacrylamide in my country is different from that of developed countries. The industry is the largest user and the second is water treatment. Polyacrylamide PAM for water treatment is the most widely used polymer flocculant, which accounts for 50% of the municipal water supply and drainage consumption. It is currently used in large quantities for sewage treatment. Polyacrylamide has achieved obvious effects on improving the flocculation effect, saving alum consumption, removing algae, reducing mutagenicity, improving water quality, and coping with sudden water quality accidents. Polyacrylamide for domestic sewage treatment
In addition to domestic sewage, the sewage treatment plant also has industrial wastewater, which is treated at the same time. Most of the treatment methods use activated sludge method.
Advantages of polyacrylamide in the treatment of municipal sewage:
Improve flocculation effect, overcome floc floating during dry season, save alum consumption and reduce water purification cost. Low temperature and low turbidity, organic matter accounts for a larger proportion of the turbidity components in the water. Single dosing of aluminum sulfate and polyaluminum will form flocs with loose, light, and difficult to precipitate. After adding 0.025-0.05mg/L of polyacrylamide to aid coagulation, due to its huge adsorption surface area and excellent bridging ability, the volume of the flocs produced by the reaction increases, the specific gravity increases, the sedimentation speed increases, and the sedimentation capacity of the sedimentation tank The turbidity of the effluent is greatly reduced.
Improve water quality, remove color, remove organic matter, remove algae, and reduce mutagenicity. Due to the coagulation aid effect of polyacrylamide, the turbidity of the effluent is significantly reduced, and the content of organic matter and algae has a very close relationship with the turbidity. According to experts, when the turbidity is reduced to 0.5 degrees, the organic matter in the water can be removed by 80%, so Adding polyacrylamide to aid coagulation can effectively remove organic pollution and improve drinking water quality. The chroma removal rate is increased by more than 10%, the water removal organic matter is decreased by more than 46%, and the algae removal rate is increased by 16-26%. The mutagenicity of the effluent of the sedimentation tank decreased, from strong positive to positive, which proved that the turbidity of the effluent was reduced, and a considerable part of the organic matter was removed, thus improving the mutagenicity of the effluent.