Printing and dyeing industry with a large amount of water, usually 1 tons of textile printing and dyeing processing of water consumption of 100 tons a year, of which 80% of the 90% to the printing and dyeing wastewater discharge. The commonly used treatment methods are recycling and harmless treatment.

        Recycling: (1) according to the water quality characteristics of wastewater can be respectively recycled, such as bleaching scouring wastewater and dyeing printing wastewater diversion, the former can convection washing, water use, reduce emissions; (2) the lye recycling, usually by evaporation recovery, such as large amount of lye, available three evaporation recovery lye, a small amount of available film evaporation recovery; (3) dye recovery, such as acidification can become hidden Pakistan indanthren dye acid, colloidal particles, suspended in the residual liquid, after sedimentation and filtration after recycling.

        Harmless treatment can be divided into: (1) physical treatment method of precipitation and adsorption method. The precipitation method is mainly used to remove suspended matter in wastewater, and the adsorption method is mainly to remove the dissolved pollutants in the wastewater and. (2) chemical treatment methods include neutralization, coagulation and oxidation. Is to adjust the pH of wastewater neutralization method, also can reduce the chroma of wastewater; coagulation of disperse dyes and colloidal substances in wastewater; in reducing substances oxidation in wastewater by oxidation method, the sulfur dyes and vat dyes precipitate. (3) biological treatment methods include activated sludge, biological rotating disk, biological rotating cylinder and biological contact oxidation method. In order to improve the effluent quality, meet the discharge standards or recycling requirements, it is often necessary to adopt several methods to deal with.