The SS and COD of papermaking wastewater are relatively high. The COD is mainly composed of soluble COD and insoluble COD. The insoluble COD accounts for a relatively large proportion. When the SS of the sewage is removed, the insoluble COD is also removed at the same time. Papermaking wastewater mainly solves SS and COD.

The following methods are mainly used to remove SS and COD from wastewater:

1, air floatation and sedimentation

PAM and polyaluminum chloride are used as flocculants in both air flotation and sedimentation methods. In the paper industry, cationic PAM is generally used as a flocculant. Since cationic PAM is a linear polymer compound, it has various activities. The group can be affinity with many substances and adsorb to form hydrogen bonds. It is mainly a colloidal negatively charged colloid with functions such as turbidity removal, decolorization, adsorption and adhesion. It is suitable for organic colloidal content in dyeing, paper making, food, construction, metallurgy, mineral processing, coal powder, oil field, aquatic product processing and fermentation. High wastewater treatment, especially suitable for dewatering of municipal sewage, municipal sludge, paper sludge and other industrial sludge. PAM and polyaluminum chloride can form a good floc in air floatation or sedimentation method, and the moisture leaves, can effectively remove SS90% or more, remove the chromaticity by about 95%, remove COD85--95%, and thus treat The wastewater has a clear water quality and can be recycled completely. The sediment can also be reused and pressed into cardboard.

2, biochemical and physical and chemical combination method

Biological treatment is the use of microbial metabolism to convert organic pollutants and inorganic microbial nutrients in wastewater into stable, harmless substances. Common methods include activated sludge, biofilm, and anaerobic digestion. The biological treatment method can also be classified into aerobic treatment and anaerobic treatment according to whether or not oxygen is supplied. The removal rate of SS by oxidation ditch can reach 70%-80%; the removal rate of COD is about 85%; the removal rate of BOD5 can be up to 95%.

In the papermaking wastewater treatment, no matter what method is adopted, the COD, BOD, SS and other indicators using PAM treatment wastewater are greatly reduced, and the discharge standard can be basically achieved.