Pulping processes such as fiber separation, bleaching and papermaking, dilution, pressing, and drying process eliminate high concentrations of pollutants such as fibers, inorganic salts, and pigments from the effluent, known as Heishui

◆In the process of washing and bleaching, a large amount of middle water containing high concentration of lignin, cellulose and resinates, which are difficult to biodegrade, is produced

◆ Paper machine discharge containing a large number of fibers, fillers and rubber waste water, that is, white water

Characteristics of sewage

◆ The content of COD and SS in papermaking wastewater is high, and the chroma is serious.

◆ The concentration of SS and COD in papermaking wastewater is relatively high, while COD is composed of insoluble COD and soluble COD, which usually accounts for most of the total COD, most of the insoluble COD was removed at the same time.

Method

The quality of recycled water is not very high, most of the sewage after a simple pre-treatment, the removal of sewage sand, large particles of suspended matter can be reused. The rest of the waste water is then passed through a grid to intercept the short fibers in the sewage. The short fibers can be recycled and reused. The waste water after passing through the grid enters the regulating tank, which mainly regulates the quantity and quality of the sewage. The front part of the regulating tank is equipped with mechanical agitation, after PAC and Pam were added, the coagulated sewage was transported to the high-level sedimentation tank by the lifting pump. After sedimentation, the supernatant flowed into the shallow tank air floatation for advanced treatment, therefore, in the air flotation after the installation of biological filter to ensure that sewage discharge standards.