Training and dyeing wastewater is one of the main sources of water pollution, and its characteristics are large amount of sewage and difficult to deal with. It is estimated that the average water consumption of a standard fabric with a 100-meter 100-meter is about 2.5 tons, and the wastewater composition is complex and has high color. At the same time, the wastewater contains a large amount of organic matter, which makes its CODcr value high, its alkalinity high, and difficult to deal with.
At present, the main treatment methods are divided into physical method, chemical method, physical chemical method and biochemical method. In recent years, the research on the use of photocatalysis and electrochemistry to treat printing and dyeing wastewater has been paid attention to. However, physical and chemical treatment methods are usually costly, and the waste generated is more difficult to deal with, the efficiency is not high, and the application is limited. The biological treatment method has the advantages of simple operation, low operating costs, no secondary pollution, and environmentally friendly, and is increasingly valued in the treatment of printing and dyeing wastewater.
At present, aerobic biological method, anaerobic method and combined treatment technology are mainly used in China. The aerobic method of treating printing and dyeing wastewater is divided into activated sludge method and biofilm method. Anaerobic method degrades dyes by anaerobic degradation, and dyes containing azo groups, anthraquinone groups and triphenylmethane groups can be degraded. However, the degradation products of these dyes are aromatic amine compounds, which are carcinogens, and cannot be further degraded under anaerobic conditions, that is, they cannot be completely degraded to achieve inorganicity of the dye. Therefore, the dyeing wastewater is directly treated with an anaerobic reactor, and few Report. However, the effectiveness of the new high-efficiency anaerobic treatment device has been greatly improved, and the requirements for incoming water COD concentration have been greatly reduced. Wastewater with a COD value of 2000 mg/l can also meet the standards through anaerobic digestion of primary biological treatment. The combined treatment technology is the combination of anaerobic method and aerobic method, that is, the anaerobic and aerobic processes are connected to coordinate the treatment of printing and dyeing wastewater. Among them, anaerobic treatment mainly causes some polymer substances with poor biochemical properties in the printing and dyeing wastewater to hydrolyze and acidify, become smaller molecules, or change the molecular structure of difficult-to-degrade organic matter, thereby improving the biochemical properties of wastewater. Create conditions for aerobic treatment. At the same time, the remaining sludge produced in the aerobic stage can also be refluxed to the anaerobic tank. Since the anaerobic stage has a solid residence time for a sufficiently long solids, the sludge can be thoroughly digested, so that the entire system is basically free of residual sludge. Mud discharge.
The current main development direction of printing and dyeing wastewater treatment is the combination of microorganisms and treatment technology. Many environmental engineers are committed to screening highly efficient degrading bacteria and building genetically engineered bacteria to leverage the vast resources of nature to serve humanity. However, the newly developed highly efficient bacteria used in wastewater treatment may not necessarily achieve the expected strengthening effect. Whether bacterial strains can occupy an advantage in the treatment system, whether complex components in wastewater will inhibit their growth… many factors will affect the treatment effect. Therefore, the application of biotechnology must undergo strict environmental safety testing and evaluation. At the same time, the degradation mechanism of dyes and the metabolic mechanism of microorganisms need to be further studied and clarified.
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