What are the advantages of polyaluminium chloride in the field of water treatment engineering?

‌In the field of water treatment engineering, the demand forPolyaluminum chloride flocculants has increased rapidly at home and abroad, especially in water treatment, where it has gradually replaced traditional coagulants and become the mainstream flocculant. A large number of application practices have proved that the use of Polyaluminum chloride instead of traditional iron and aluminum salt coagulants can significantly improve the purification efficiency of water plants, reduce treatment costs, and improve effluent water quality. Its four major advantages are:

1. Excellent coagulation, deturbidity removal, decolorization and humus removal effects and a wider range of pH ranges. Polyaluminum chloride not only has a strong coagulation and deturbidity removal effect, but also has obvious decolorization and humus removal effects. Under the same treatment conditions, the dosage of polyaluminium chloride is reduced by 2/3 compared with traditional aluminum salts to achieve the best flocculation effect. Under the same dosage conditions, the use of Polyaluminum chloride can obtain a lower residual turbidity than traditional aluminum salts, so the same treatment results can be obtained at a lower dosage. In addition, the pH range used by polyaluminium chloride is much wider than that of traditional aluminum salts.

2. Good low-temperature coagulation treatment efficiency and sedimentation efficiency. Generally, in low-temperature water (<5℃), the coagulation and turbidity removal efficiency of traditional coagulants is significantly reduced and the effluent water quality deteriorates. However, the use of polyaluminium chloride can achieve good coagulation and turbidity removal effects regardless of low or normal temperature water. In addition, polyaluminium chloride can significantly improve the solid-liquid separation efficiency, improve the sedimentation filtration and sludge dewatering performance, thereby shortening the residence time of the sedimentation tank and increasing the water output. In addition, since the generated floccules are large and compact, they are easy to filter and dewater.

3. Low residual aluminum content The residual aluminum content in the water after Polyaluminum chloride treatment is very low. The residual aluminum content in the water treated with traditional aluminum sulfate is generally 150~255μg/L, while the residual aluminum content in the water treated with polyaluminium chloride is only 40~55μg/L.

4. Simple operation The operation process of Polyaluminum chloride salt treatment is much simpler than traditional treatment methods. The flocculation process is not only an ancient water purification method, but also a widely used and common unit operation process technology in many water treatment process technologies today. As an indispensable pre-key link in many treatment processes, the effect of the flocculation process often determines the operating conditions, final effluent quality and cost of the subsequent process. Therefore, it has always been an important research and development field in water treatment engineering.