Solids are classified into brown, yellow and white according to color; Inorganic polymer coagulant, referred to as polyaluminum (PAC). It has the characteristics of good spray drying stability, wide water area, fast hydrolysis speed and strong adsorption capacity. It has become a new water purification material and inorganic polymer coagulant, and is widely used for the purification and treatment of domestic water, urban sewage and industrial wastewater.