One of the factors hindering the development of the textile industry is environmental protection. Wastewater treatment is a major problem in environmental protection. In 2008, textile wastewater discharge accounted for 10.6% of national wastewater discharge, and emissions were 2.3 billion tons, ranking industrial emissions. In the third place, COD emissions amounted to 3.14 billion tons, ranking fourth in industrial emissions, accounting for 7.76% of national industrial wastewater discharge. Printing and dyeing wastewater has been the focus of wastewater treatment research with large emissions and high processing difficulty. difficulty. At the same time, with the rapid development of China's economy, the shortage of water resources has become a limiting factor restricting the further development of China's printing and dyeing industry. In order to achieve sustainable development of the printing and dyeing industry, the recycling of printing and dyeing wastewater has become the key to achieve this goal.

Printing and dyeing wastewater has high content of organic matter, large alkalinity and large changes in water quality. The wastewater contains dyes, auxiliaries, slurries, oils, acids and bases, fiber impurities, sand substances, inorganic salts, large amount of printing and dyeing wastewater, and is industrial wastewater. Large emitters, the composition is more complicated, and it is one of the more difficult industrial wastewater. How to deal with it? The Noel Group, a PAM manufacturer, tells you through a lot of facts.

According to the characteristics of printing and dyeing wastewater, measures for repeated reuse or comprehensive utilization of wastewater are generally used. In China, the treatment of printing and dyeing wastewater is mainly combined with physicochemical treatment and secondary special treatment. The physicochemical treatment is mainly composed of coagulation sedimentation and coagulation flotation. In the biochemical treatment facilities that have been put into operation, most of them are used. Activated sludge method, the application of SBR process is also gradually increasing. Below we mainly introduce the coagulation pretreatment process and the subsequent biochemical treatment process.

The coagulation method is to add flocculant to the waste water, so that most of the water-insoluble dye particles and colloidal organic matter in the printing and dyeing sewage are condensed into large particles by potential difference, and then removed by natural precipitation, air flotation and the like. Due to the strong adsorption capacity of the flocculation in the coagulation process, some water-soluble organic matter can be adsorbed and removed. More than 80% of the suspended organic pollutants are removed after the coagulation treatment of the printing and dyeing wastewater. At the same time, the removal rate of chromaticity can also reach 50-95%. The sewage treatment agent used in the treatment process is PAM and polyaluminum chloride, and calcium hypochlorite is used as a decolorizer. The process focuses on aerobic biological contact oxidation, the main function of which is the degradation of organic matter. The anionic PAM and non-ionic PAM produced by Noel Group are effective as coagulant, and the cost is low. The cationic sludge is selected for dehydration of activated sludge. Generally, cations with relatively low ionicity are selected, and the molecular weight is basically more than 10 million.