Explain the use of polyaluminum chloride on the decolorization effect of dye wastewater Treatment of textile printing and dyeing wastewater discharge of the industry are generally high chroma, the general emphasis on water treatment is the decolorization effect, how can play a decolorizing effect is the dye wastewater to reach the country Emission Standards. Currently on the market generally take the approach is to use: polyaluminum chloride or polyaluminum chloride, polyferric sulfate at the same time complex with polyacrylamide to achieve the desired effect. The effects of these agents on the treatment of dye wastewater solutions are higher than those of the individual components. In the case of a certain ratio, the influence of raw water pH and dosage on the decolorization rate is greater, and other factors have little effect on the decolorization rate. In the best conditions decolorization rate of up to 99.7%. Polyaluminum chloride has the advantages of high decolorization efficiency on dye wastewater, good sedimentation performance of flocs, and is suitable for pretreatment of alkaline dye wastewater. Polyaluminum chloride (PAC) is a widely used inorganic flocculant, but its use in large quantities, if the polyacrylamide and polyaluminum chloride synergies, will greatly reduce the dosage of PAC. And can achieve good treatment effect, low cost and so on. At home many traditional dye wastewater treatment, but also useful basic aluminum chloride + polyacrylamide, also can play the role of water purification, but still recommend a new type of PAC, the new type of PAC Is an alternative to the older generation of basic aluminum chloride. Although PAC has a good decoloration effect on dye wastewater, it must be used with polyacrylamide to achieve better results. Dyeing wastewater in textile printing and dyeing industry has the following characteristics: 1. Most organic compounds in wastewater are benzene, naphthalene, anthracene, quinone and other aromatic groups as the parent, and with a chromogenic group, the color is deep, the color of 500 ~ 500000, there is a strong pollution. 2. Due to the needs of the production process and molecular structure, dye materials and intermediate molecules often contain polar groups, which enhances water solubility and causes large material loss. Wastewater usually contains many raw materials and by-products, such as halides, nitro compounds, amino compounds, aniline, phenols and other organic compounds and sodium chloride, sodium sulfate, sulfides and some inorganic salts, high concentrations, Up to 1000 ~ 73000mg / L. 3. Dye wastewater mostly acidic, and some were alkaline, salt content are generally large.