Printing and Dyeing Wastewater Polyaluminium Chloride Summary of the reasons for the poor decolorization? Printing and Dyeing Wastewater Polyaluminium Chloride Summary of the reasons for the poor decolorization? A printing and dyeing plant in Foshan recently encountered problems in the treatment of waste water, thus, call my plant to consult, ask questions are as follows: Why use polymeric aluminum chloride bleaching effect is poor? Is it because there is no reason to add alkali? (Currently PH value of 6 or so) In fact, the role of PAC in the treatment of wastewater flocculation, that is, in the process of aluminum polyaluminate into aluminum hydroxide adsorption of insoluble materials, the particles become larger and heavier heavy sink. If the color of the water is mainly produced by some insoluble water colored particles, then the decoloring effect is also ideal, if the color is mainly made of some water-soluble molecules, then the decolorization effect is poor.