How to treat 1500 cubic meters of textile printing and dyeing wastewater?
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Wastewater discharged from processing cotton, hemp, chemical fiber and its blended products, silk-based printing and dyeing, woolen dyeing and finishing, and silk factories. The fiber type and processing technology are different, and the water quantity and quality of the printing and dyeing wastewater are also different. Among them, the amount of waste water in printing and dyeing plants is relatively large, and 100-200t of water is consumed per 1t of textile processing, of which 80% -90% is discharged as waste water. Printing and dyeing wastewater has the characteristics of large water volume, high content of organic pollutants, large alkalinity, and large changes in water quality. It is one of the difficult industrial wastewaters. The wastewater contains dyes, slurries, additives, oils, acids, alkalis, and fiber impurities. , Sand materials, inorganic salts, etc.
The four processes of printing and dyeing must discharge wastewater. The pretreatment stage (including singeing, desizing, smelting, bleaching, mercerization, etc.) must discharge desizing wastewater, cooking wastewater, bleaching wastewater, and mercerizing wastewater. Dyeing wastewater, printing wastewater and printing wastewater are discharged during the printing process, and finishing wastewater is discharged during the finishing process. Printing and dyeing wastewater is a mixed wastewater of the above types of wastewater, or a comprehensive wastewater other than bleaching wastewater.
The water quality of printing and dyeing wastewater varies with the type of fiber used and the processing technology. The pollutant composition varies greatly. The pH value of general printing and dyeing wastewater is 6-10, CODcr is 400-1000 mg / L, and BOD5 is 100-400 mg. / L, SS is 100-200 mg / L, and chroma is 100-400 times. However, when the printing and dyeing process, the type of fiber used and the processing process change, the wastewater quality will change significantly. For example, when the waste water contains alkali-reduced waste water generated in the polyester silk printing and dyeing process, the CODcr of the waste water will increase to above 2000-3000 mg / L, BOD5 will increase to above 800 mg / L, and the pH value will reach 11.5 ~ 12, and the water quality of the waste water deteriorates with the increase of the amount of added waste water from the polyester simulated silk printing and dyeing alkali.
1500 cubic meters of textile printing and dyeing wastewater treatment methods:
At present, the methods of printing and dyeing wastewater treatment are physical, chemical and biological.
Physical method
Among the physical treatment methods, the most commonly used is the adsorption method. This method is to mix the powder or particles of porous materials such as activated carbon and clay with the wastewater, or let the wastewater pass through the filter bed composed of its particulates, so that the pollution in the wastewater The substance is adsorbed on the surface of the porous substance or removed by filtration. At present, activated carbon adsorption method (mostly used for tertiary treatment) is mainly adopted abroad. This method is very effective for removing dissolved organic matter in water, but it can not remove colloids and hydrophobic dyes in water, and it only has good adsorption performance for water-soluble dyes such as cationic dyes, direct dyes, acid dyes, reactive dyes, etc. Saito T's research shows that the adsorption rate of activated carbon, BOD removal rate, and COD removal rate are 93%, 92%, and 63%, respectively, and the adsorption capacity of activated carbon can reach 500 mg COD / g carbon. If sewage is aerated first, then Will speed up the adsorption rate. But if the wastewater BOD5> 200 mg / L, this method is not economical.
There are many kinds of adsorbents used in the adsorption treatment. The selectivity of the adsorbent to the dye should be considered in the project. The adsorbent should be selected according to the quality of the wastewater. Studies have shown that in printing and dyeing wastewater with pH = 12, using silicon polymer (methyloxygen) as an adsorbent, the removal rate of anionic dyes can reach 95% to 99%.
Kaolin electricity is an adsorbent. Studies have shown that after long-chain organic cation treatment, kaolin can effectively absorb the yellow direct dye in wastewater. In addition, activated diatomaceous earth and coal slag are also used domestically to treat wastewater from traditional printing and dyeing processes. The cost is lower and the decolorization effect is better. The disadvantage is that the amount of sludge is large and further processing is difficult.
Chemical method
a Coagulation method
There are mainly coagulation precipitation method and coagulation air floatation method. Most of the coagulants used are mainly aluminum salts or iron salts. Among them, basic aluminum chloride (PAC) has better bridging adsorption performance, while sulfuric acid is used. The price of ferrous iron is low. In recent years, the use of polymer coagulants has been increasing abroad, and there is a tendency to replace inorganic coagulants. However, due to price reasons, it is rare to use polymer coagulants. It is reported that the weak anionic polymer coagulant is the most widely used, and if used in combination with aluminum sulfate, it can exert better effects. The main advantages of the coagulation method are simple process flow, convenient operation and management, less equipment investment, less floor space, and high decolorization efficiency for hydrophobic dyes; the disadvantages are higher operating costs, more sludge volume, and difficult dehydration The effect of water-based dye treatment is poor.
b Oxidation
Ozone oxidation method is widely used abroad. Zima SV et al. Summarized the mathematical model study of ozone decolorization of printing and dyeing wastewater. When the ozone dosage is 0.886 g O3 / g dye, the decolorization rate of light brown dye wastewater reaches 80%; the study also found The amount of ozone required for continuous operation is higher than that required for intermittent operation, and the installation of a separator in the reactor can reduce the amount of ozone used by 16.7%. Therefore, the use of ozone oxidation decolorization should be designed as a reactor that operates intermittently, and it may be considered to install a partition in it. Ozone oxidation method can obtain good decolorization effect for most dyes, but it has poor decolorization effect for water-insoluble dyes such as vulcanization, reduction and paint. Judging from the operating experience and results at home and abroad, the decolorization effect of this method is good, but it consumes a lot of power, and it is difficult to promote it on a large scale. The photo-oxidation method has a high decolorization efficiency for printing and dyeing wastewater, but the equipment investment and power consumption need to be further reduced;
c Electrolysis
Electrolysis has a good treatment effect on the treatment of printing and dyeing wastewater containing acid dyes, with a decolorization rate of 50% to 70%, but it has a poor treatment effect on wastewater with deep colors and high CODcr. Studies on the electrochemical performance of dyes show that the order of CODcr removal rate of various dyes during electrolytic treatment is: sulfur dyes, vat dyes> acid dyes, reactive dyes> neutral dyes, direct dyes> cationic dyes. This method is currently being promoted and applied.
Biological method
Since the 1970s, biological treatment of printing and dyeing wastewater has been the mainstay in China, accounting for more than 80%, especially aerobic biological treatment. From the current situation. Among the biological treatment methods for printing and dyeing wastewater in China, surface accelerated aeration and contact oxidation methods are the majority. In addition, the blast aeration activated sludge method, jet aeration activated sludge method, biological turntable, etc. are also used, and the biological fluidized bed is still in the experimental application stage. But because the biological removal rate of chroma is not high, it is generally around 50%, so when the chromaticity of the effluent is high, it needs to be supplemented by physical or chemical treatment.
Aerobic biological treatment has obvious effect on BOD removal, generally up to about 80%, but the removal rate of chroma and COD is not high, especially the widespread application of PVA and other chemical slurry, surfactant, solvent and pibuine reduction technology Not only will the COD of the printing and dyeing wastewater reach 2 000-3 000 mg / L, but also the BOD / COD will be reduced from 0.4 to 0.5 to less than 0.2. It is more and more difficult for simple aerobic biological treatment, and the effluent is difficult to meet the standard; in addition The high operating cost of the aerobic biological treatment method and the problem of residual sludge treatment or disposal have always been a problem that has not been solved well in the field of wastewater treatment. According to data reports, general sludge treatment or disposal costs account for 50% to 70% (overseas) of the entire sewage treatment plant cost, and also account for about 40% in China. Due to the above reasons, the anaerobic biological treatment technology of printing and dyeing wastewater has begun to attract people's attention.
This is the detailed dissection of 1500 cubic meters of textile printing and dyeing wastewater made by Shandong Longxin Environmental Protection. If you also have textile printing and dyeing wastewater to be treated, you can contact the customer service of the website or call to consult! 
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