The textile printing and dyeing industry is one of the main industries in the world. However, behind the colorful and multi-color, it has caused serious pollution of the water environment. The wastewater discharged from the textile printing and dyeing industry has a high chroma. How to decolorize has also become a headache for enterprises.

In general, printing and dyeing textile wastewater has the following characteristics: most of the organic matter in the wastewater is based on aromatic groups such as benzene, naphthalene, anthracene, and quinone, and has chromogenic groups, the color is very deep, and the chroma is 500 to 500,000. It is highly polluting; due to the needs of the production process and molecular structure, dye substances and intermediate molecules often contain polar groups, which enhance water solubility and cause a large amount of material loss. Wastewater usually contains many raw materials and by-products, such as halides, nitro compounds, amino compounds, anilines, phenols and other series of organic compounds and some inorganic salts such as sodium chloride, sodium sulfate, sulfide, etc., with high concentration, high toxicity, and general COD It can reach 1000~73000mg/L; dye wastewater is mostly acidic, and some are alkaline, and generally contains a lot of salt.

In view of the difficult decolorization and treatment of textile printing and dyeing wastewater, the treatment method generally adopted on the market at present is to use: polyaluminum chloride or polyaluminum ferric chloride, and polyferric sulfate to simultaneously compound polyacrylamide to achieve the desired effect. The treatment effect of these agents on the dye wastewater solution is higher than the treatment effect of each individual component. In the case of a certain ratio, the pH of the raw water and the dosage of the agent have a greater impact on the decolorization rate, and other factors have a small impact on the decolorization rate. Under the best conditions, the decolorization rate is as high as 99.7%. However, polyaluminum chloride has the advantages of high decolorization rate of dye wastewater and good floc settlement performance, which is suitable for the pretreatment of alkaline dye wastewater. Polyaluminum chloride (PAC) is a widely used inorganic flocculant, but it exists in a large amount. If polyacrylamide and polyaluminum chloride are used in synergy, the dosage of PAC will be greatly reduced. And it can achieve the characteristics of good treatment effect and low cost.