The Key Role and Case Analysis of Water Treatment Chemicals in Sewage Treatment and Reuse

With the increasingly prominent problem of water shortage, sewage treatment and reuse has become an important way to alleviate the pressure on water resources and realize the recycling of water resources. In the process of sewage treatment and reuse, water treatment chemicals play a key role, which can effectively remove pollutants in water, improve the quality of effluent, and meet the needs of different reuse scenarios. Combining with practical cases, this article will elaborate on the core role of water treatment chemicals in sewage treatment and reuse, and show their important value in the recycling of water resources.

The core role of water treatment chemicals in sewage treatment and reuse is reflected in three aspects: first, removing pollutants in water, including suspended solids, organic matter, heavy metal ions, phosphorus, etc., to ensure that the effluent quality meets the standards; second, improving water quality indicators, such as adjusting the pH value of water and reducing water hardness, to make it meet the reuse requirements; third, ensuring the stable operation of the reuse system and preventing pipeline scaling, corrosion and microbial growth. For example, in industrial wastewater reuse, flocculants are added to remove suspended solids and organic matter in water, corrosion and scale inhibitors are added to prevent scaling and corrosion of the circulating water system, and disinfectants and bactericides are added to kill microorganisms, finally realizing the recycling of wastewater.

The following will specifically illustrate with two typical cases: Case 1: A production wastewater treatment and reuse project of a chemical enterprise. The enterprise's wastewater contains high-concentration organic matter, heavy metal ions and phosphorus, and the reuse goal is to be used as supplementary water for circulating cooling water. The project adopts the process of "coagulation sedimentation + biochemical treatment + advanced filtration". In the coagulation sedimentation stage, polyaluminum chloride (PAC) is added as a coagulant and cationic polyacrylamide (PAM) as a flocculant, which effectively removes more than 80% of suspended solids and more than 60% of organic matter in water; in the advanced treatment stage, polyepoxysuccinic acid (PESA) is added as a corrosion and scale inhibitor to adjust the hardness and pH value of water; finally, chlorine dioxide is added for disinfection and sterilization. The treated effluent quality meets the requirements of "Code for Design of Industrial Circulating Cooling Water Treatment", the reuse rate reaches 70%, and the enterprise saves nearly one million yuan in water resource costs every year.

Case 2: A reclaimed water reuse project of a municipal sewage treatment plant. The reuse goal of this project is to be used for urban greening, road cleaning and landscape water. The project adopts the process of "activated sludge process + flocculation filtration + disinfection". In the flocculation filtration stage, polyaluminum ferric chloride (PAFC) and anionic polyacrylamide (PAM) are added to strengthen the removal of suspended solids and chroma in water; in the disinfection stage, ozone disinfection is adopted instead of traditional chlorine disinfection to avoid producing harmful by-products. The COD, suspended solids, chroma and other indicators of the treated effluent all meet the standards of "Water Quality Standard for Urban Mi