Polyaluminum chloride in water treatment, with the following four advantages First, the excellent coagulation Turbidity and remove turbidity removal results and the more common use of pH limits. Polyaluminum chloride not only has a strong condensate Turbidity results, but also has a clear decolorization and humus removal results. The best flocculation is achieved at the same disposal, with the polyaluminum chloride dosage being reduced by as much as two-thirds over the traditional aluminum salt. With the same dosage, the use of polyaluminum chloride gives lower residual turbidity than the conventional aluminum salt, thus enabling the same treatment results to be obtained at lower dosages. In addition, the use of polyaluminium chloride limits the pH to a much wider extent than conventional aluminum salts. Second, superior cryogenic coagulation disposal efficiency and settlement efficiency. Ordinary low temperature water (& lt; 5 ℃), the coagulant turbidity removal efficiency of the traditional coagulant clearly reduce and cause deterioration of effluent quality, the use of PAC, whether it is low temperature or room temperature water, can get better Turbid coagulation results. In addition, polyaluminium chloride can clearly move the solid and liquid away from the power, improve sedimentation and sludge dewatering function, and then shorten the settling tank residence time, add water production. In addition, since the flocs produced are large and compact, they are then easily filtered and dewatered. Third, the lower residual aluminum content. The content of residual aluminum in water after PAC polluted is very low, the content of residual aluminum in the conventional aluminum sulfate treated water is generally 150-255μg / L, while the content of residual aluminum in polyaluminum chloride treated water is only 40-55μg / L . Fourth, the operation concise. Polyaluminum chloride treatment options when the operation is relatively traditional disposal methods to be much more concise.