The problem of sludge treatment in the production process of printing and dyeing plants usually makes the manufacturers more difficult, because the printing and dyeing sludge is generally high in inert substances, for example, the sludge from washing and bleaching wastewater of jeans has high sand content, high heavy metal content (compared with the sludge from urban domestic sewage), low content of organic matter and pathogenic bacteria, and low calorific value. As the printing and dyeing industry itself uses different raw materials, product varieties, product processing methods and so on, the sludge composition is not the same. The sulfide content of enterprises using sulfide dyes is bound to be higher. Therefore, the selection and dosage of chemicals in printing and dyeing sludge treatment should be treated differently according to different sludge sources. The scale of sewage treatment, sludge production, source of chemicals, dosage of chemicals, operation cost and moisture content of sludge cake should be considered comprehensively according to local conditions.

At present, most of the printing and dyeing plants are limited by their scale, and the amount of wastewater is less than 100000 cubic meters per day. It is not advisable to use large areas of land for natural drying or to set up incinerators and other facilities, especially in rainy and humid countries, where drying fields are in vain. Therefore, when the small-scale sewage treatment plant is used for treatment, the sludge can be preliminarily conditioned and pressed. In the process of dewatering, a large number of flocculants are used as sludge dewatering agents. There are many flocculants used for sludge treatment, such as aluminum sulfate, ferric chloride, ferrous sulfate, polyaluminum chloride, polyaluminum sulfate, polyacrylamide, etc. all kinds of agents have their application scope, advantages and disadvantages. Different wastewater treatment plants use different chemicals in each process of printing and dyeing wastewater treatment, but sludge treatment is mainly considered from the following aspects:

① The medicament has wide sources and is easy to buy;

② The price is cheap;

③ The range of pH is wide;

④ The chemical has little corrosiveness;

⑤ Good flocculation effect and less consumption;

⑥ The filtrate returned to the sewage treatment system has no negative impact.

Polyaluminum chloride and polyacrylamide are the main agents for sludge treatment in printing and dyeing plants. Polyacrylamide is generally divided into anion type, cation type and non-ionic type. The selection of polyacrylamide should be based on the characteristics of sludge and different treatment methods. As long as the solid content of dehydrated dry sludge is more than 25%, it can meet the transportation requirements. The printing and dyeing plants can also accept the investment, operation cost and sludge disposal methods.