What are the three major methods of producing PAC pollutions? Nowadays, in China's water treatment field, the adoption of cohesive technology is the most common key operation method for water and wastewater treatment. The treatment effect largely determines the operation of subsequent processes As well as the water quality and cost of water. The key to the efficiency of cohesion treatment lies in the proper selection and use of flocculants. Therefore, giving priority to the development of efficient and cheap coagulants is an important guarantee for improving the water purification efficiency and reducing the cost of making water, which is of great significance. Polyaluminum chloride is currently the largest industrial production, the most widely used flocculant, its preparation began in the 60s in Japan, China's rapid development in recent years. Poly aluminum as the basic raw material, but also derived a variety of composite inorganic polymer flocculant. Introduced a small amount of sulfur and phosphorus in the polymerization of aluminum can be made of poly aluminum thioaluminate, poly phosphorus phosphorus chloride, the use of anionic polymerization increases the degree of polymerization and thus improve the water purification effect. China's aluminum chloride method are: 1, waste aluminum ash, coal gangue, bauxite acid solution or alkali-soluble method, this method are mostly crude products; 2, industrial aluminum hydroxide gel as raw material , Using hot-pressing hydrochloric acid one-step or two-step preparation, due to the continuous rise in raw material prices in recent years, high production costs; 3, aluminate calcined acid transfer method, the method of preparation of lower cost, easy to get solid products, Liquid products cloudy, more impurities and not easy to filter or stand to remove. In order to overcome the shortcomings of the above methods, we use the electrochemical principle, tried electrochemical preparation of polyaluminum chloride, study the product performance.