Application of polyacrylamide in the treatment of urban domestic sewage

Application of polyacrylamide treatment of urban domestic sewage:

In the treatment of urban sewage, Polyacrylamide Polyaluminum Chloride Water Treatment Chemicals， as the object of treatment, the main substances are organic matter and solid matter expressed by BOD and COD, and the treatment methods are biological treatment methods such as activated sludge method and biological turntable method. Moreover, due to a marked increase in eutrophication in enclosed waters such as lakes and bays in recent years, the nitrogen and phosphorus responsible for this have been partially eliminated.

Municipal wastewater treatment is generally aimed at removing BOD (biochemical oxygen demand) substances. In large sewage treatment plants, precipitation-centered primary treatment and bio-centered secondary treatment are mostly used. Sometimes in order to remove nitrogen, phosphorus and other substances, but also after biological treatment, sewage tertiary treatment. In the future development of urban sewage treatment plants, in addition to the continuous increase in number, the proportion of secondary treatment plants should be gradually increased, and the construction of tertiary treatment plants began.

 

Flow chart of sludge treatment in sewage plant

The application of polyacrylamide in water treatment in developed countries, the United States accounts for 63 percent of the total amount of polyacrylamide, Western Europe accounts for 35 percent, and Japan accounts for 49 percent. The consumption composition of polyacrylamide in China is different from that of developed countries, and industry is the first major user, and the second is water treatment. Polyacrylamide PAM for water treatment is the most widely used polymer flocculant, accounting for half of the municipal water supply and drainage amount of 50% is currently used in sewage treatment. Polyacrylamide can improve flocculation effect, save alum consumption, remove algae, reduce mutagen, improve water quality and cope with sudden water quality accidents.

In addition to domestic sewage, sewage treatment plants also have industrial wastewater, which is treated at the same time. Most of the treatment methods were activated sludge.

The advantages of polyacrylamide treatment of urban domestic sewage:

Improve flocculation effect, overcome floc floating in dry period, save alum consumption, reduce the cost of water purification. Low temperature and low turbidity, relative to the turbidity composition of water, organic matter accounts for a larger proportion, the single addition of aluminum sulfate and polyaluminum, the formation of the flocculant structure is loose, light, difficult to precipitate. After the addition of 0.025-0.05 mg/L polyacrylamide as coagulation aid, due to its huge adsorption surface area and excellent bridging ability, the volume of the flocculant generated by the reaction increases, the specific gravity increases, the settlement rate is accelerated, the sedimentation capacity of the sedimentation tank is rapidly improved, and the effluent turbidity is greatly reduced.

Improve water quality, remove chroma, remove organic matter, remove algae, reduce mutagenicity. Due to the effect of polyacrylamide coagulation, the turbidity of the effluent decreased significantly, and the content of organic matter and algae has a very close relationship with turbidity, according to experts, when the turbidity is reduced to 0.5 degrees, the organic matter in the water can be removed 80%, so the addition of polyacrylamide coagulation can effectively remove organic pollution and improve the quality of drinking water. Chroma removal rate increased by more than 10%, water removal organic matter decreased by more than 46%, algae removal rate increased by 16-26%. The mutagenicity of the effluent from the sedimentation tank decreased from strong positive to positive, which proved that the turbidity of the effluent decreased and a considerable part of organic matter was removed, thus improving the mutagenicity of the effluent.