Method for dyeing yarns by using disperse dye dyeing waste water

The invention belongs to the technical field of textile printing and dyeing, and particularly relates to a method for dyeing yarns by using disperse dye dyeing waste water. After the pH value of the disperse dye dyeing waste water is adjusted, active dye is added to obtain mixed dyeing solution, and the mixed dyeing solution is used for dyeing the yarns, wherein the yarns can be dyed by the activedye. The disperse dye dyeing waste water adopted by the method is directly applied to dyeing of pure cotton yarns without sewage treatment procedures such as decoloration, flocculation and the like,so that the discharge amount of polyester dyeing waste water is reduced, and the waste water treatment cost and the fabric production cost are reduced; and the disperse dye dyeing waste water is adopted to replace softened water to dye the pure cotton yarns, so that the use amount of normal softened water is reduced, the quality problems of staining, uneven dyeing and the like can be avoided, andthe environmental protectio