Textile printing and dyeing industrial wastewater has the characteristics of large amount of wastewater, complex water quality and great change in water quality and quantity. The treatment of industrial wastewater is generally divided into three stages, i.e. first stage, second stage and third stage.

      Grid, pre sedimentation tank or primary sedimentation tank are often used for primary treatment, and simple physical mechanical or chemical methods are used to separate suspended solids or lumps in wastewater, or neutralize the pH of wastewater.

      The secondary treatment is mainly biochemical treatment, which can effectively remove the colloidal dissolved organic pollutants and effectively improve the water quality. Biochemical method can be selected when the biodegradability of wastewater is good; chemical method can be selected when the biodegradability of wastewater is poor, such as coagulation sedimentation or pressurized flotation.

      Physical or chemical methods are often used in the tertiary treatment, and the advanced treatment is carried out to meet the discharge standards or reuse.