Application of Water Treatment Chemicals in Municipal Sewage Treatment

Municipal sewage contains a large amount of organic matter, nitrogen, phosphorus, suspended solids, and other pollutants. If it is directly discharged without treatment, it will cause serious pollution to surface water and groundwater. Water treatment chemicals play an important role in municipal sewage treatment, which can improve the treatment efficiency, ensure the effluent quality meets the discharge standards, and promote the recycling of sewage. This article introduces the application of water treatment chemicals in different stages of municipal sewage treatment.

In the primary treatment stage of municipal sewage, coagulants and flocculants are mainly used to remove suspended solids and colloidal substances. Common products include polyaluminum chloride (PAC), polyacrylamide (PAM), and ferric chloride. These chemicals can aggregate fine particles in sewage into large flocs, which are removed through sedimentation. In the secondary treatment stage, which mainly removes organic matter and nitrogen, biological treatment technologies are the main means, but water treatment chemicals also play an auxiliary role. For example, pH adjusters (such as lime and sulfuric acid) are used to regulate the pH of the aeration tank to ensure the normal growth of microorganisms; defoamers are used to eliminate foam generated during the aeration process, improving the treatment efficiency.

In the advanced treatment stage of municipal sewage, which aims to remove nitrogen, phosphorus, and trace pollutants, specialized water treatment chemicals are used. For example, phosphorus removal agents (such as aluminum sulfate, ferric sulfate, and polyferric sulfate) are used to precipitate phosphorus in sewage, reducing the phosphorus content in the effluent; denitrification agents are used to promote the conversion of nitrate nitrogen into nitrogen gas, achieving nitrogen removal. In addition, disinfectants (such as chlorine dioxide and ozone) are used in the disinfection stage to kill microorganisms in the effluent, ensuring the safety of recycled water. With the continuous improvement of municipal sewage treatment standards, the demand for high-efficiency and environmentally friendly water treatment chemicals in municipal sewage treatment will continue to increase.