On 0.3-5μm fine particles and colloidal impurities how to improve the coagulation effect? On 0.3-5μm fine particles and colloidal impurities how to improve the coagulation effect? Polyaluminum chloride can be removed by a filter with a filtration precision of 5 μm for impurities with a particle size of 5 μm or more at the time of wastewater treatment. However, it is difficult to remove fine particles and colloids with a size of 0.3-5 μm by the above conventional filtration technique. Although ultrafiltration of these particles and colloids have an absolute removal, but the hollow fiber ultrafiltration membrane is extremely serious harm. In particular, colloidal particles with a charge, is a polymer of molecules and ions, so colloids can exist stably in water, mainly due to the same-sex colloidal particles mutually exclusive results. Charged material (flocculant), which is opposite to colloidal particles, is added to the raw water to break the stability of the colloidal particles, so that the charged colloidal particles are neutralized into electricity and the dispersed colloidal particles are condensed into large lumps , And then use the filter or settlement can be relatively easy to remove. Commonly used flocculants are inorganic electrolytes, such as aluminum sulfate, polyaluminum chloride, ferrous sulfate and ferric chloride. Organic flocculants such as polyacrylamide, sodium polyacrylate, polyethylene imine and so on. Since organic flocculant polymer can neutralize the surface charge of colloidal particles to form hydrogen bonds and "bypass" the coagulation and sedimentation in a short time to complete, so that the water quality is greatly improved, so in recent years, polymer flocculants have replaced The trend of inorganic flocculants.