Effect of water quality changes on dyeing uniformity Summary: According to the comparison of water quality dyeing effects of wastewater treated with different treatment methods. Analyze the use of waste water discharged back to bleaching and dyeing. The main reason for the production of color flowers is that the conductivity of the water is high, and through the example of dyeing with reactive dyes and the analysis of water conductivity at each stage of dyeing, the process of dyeing is proved. The addition of a large amount of Yuan Mingfen and soda ash increases the metal ions in the water, which is the main reason for the high conductivity of wastewater. It is pointed out that the reuse of bleaching and dyeing wastewater should pay attention to the conductivity of wastewater. However, the conventional sewage treatment method cannot effectively remove the metal ions that lead to high conductivity of the wastewater and must be removed by reverse osmosis membrane treatment. Key words: Water quality; Dyeing uniformity; Conductivity; Printing and dyeing wastewater; Reuse; Reverse osmosis membrane treatment The shortage of water resources has become a major constraint to the current global social and economic development. In accordance with the spirit of national energy conservation and emission reduction, in order to ensure that the unit energy consumption is reduced by 20% during the “Eleventh Five-Year Plan†period, the pollutant emission reduction will be reduced by 10% and other binding indicators. National textile printing and dyeing enterprises actively take water-saving measures to improve the utilization of water as the center. Implement wastewater reuse. The amount of water used for bleaching and dyeing of knitted fabrics is large, and the dyeing process has undergone multiple water intake and drainage. In order to re-use dyeing wastewater into production, it is first necessary to understand the changes in water quality at each step of the production process. If you don't understand the water quality situation and blindly reuse it, you will not be able to achieve the desired results, or even produce side effects. Therefore, a detailed understanding and analysis of the changes in water quality during the dyeing process of knitted fabrics were conducted to understand the water quality changes. It helps to rationally select water treatment methods and properly implement wastewater reuse. I. High conductivity is the main factor affecting the reuse of printing and dyeing wastewater 1.1 Comparison of different water quality indicators Whether the dyeing wastewater can be used for production. In addition to focusing on several key indicators of color, hardness, turbidity, and pH of wastewater, the conductivity of water is an important indicator that cannot be ignored. Conductivity is the reflection of more or less metal ions in water. Water with high conductivity has less effect on the dyeing of chemical fiber products. But for the dyeing of cotton products. In particular, the dyeing of reactive dyes has a greater influence and will accelerate the dyeing rate. Causes uneven color, color stains and other issues. We carry out a variety of methods for the re-treatment of waste water discharged in compliance with standards. Take the treated water quality to conduct a contrast test. As a result, the same dye and the same dyeing process were found. Some waters have good color uniformity and are colorless. And some waters are colored quickly in the early stages. Obviously, there are phenomena of coloration. The specific conditions are shown in Table 1. Different treatment of waste water See Figure 1 for the formula. 1.2 Different water quality dyeing process Staining prescription (brown): Reactive Red 2B 2.0% Reactive Yellow s-3R 1.5% Reactive Blue s_G 1.0% Sodium Peroxide 60玑 Soda 20 g/L Staining Sampling Figure 2 is shown. The corresponding staining results are shown in Figure 3. As can be seen from Table 1 and Figure 3, when the chroma, hardness, turbidity, pH, and other indicator data meet the requirements of the production water, the water conductivity of 240 s/cm or less is well-distributed and colorless. flower; The three kinds of water quality with conductivity above 2 000 I乩s/cm had fast pre-dyeing rate, and the color was obviously changed before soda ash was added. It can be seen that the wastewater with high conductivity has a great influence on the uniformity of dyeing. Second, the main factors to improve the conductivity of dyeing wastewater In order to understand which substances in the waste water have the greatest influence on the conductivity of the water. The whole dyeing process of reactive dyes was analyzed, and the conductivity of the dyes was measured at different time intervals after addition of dyes, sodium sulphate and soda ash. 2.1 Dyeing process Oxygen bleaching prescription: Hydrogen peroxide 5.0 g/L Alkali 3.0g/L Low foam scouring agent SF_l 0.5g/L Complex Dispersant 540 0.5g/L Oxygen bleaching process curve shown in Figure 4. Staining prescription: Reactive Yellow 3GL O. 09% Reactive Yellow 5#0.36% Active Turquoise Blue SGE 0.27% Yuan Mingfen 30 s/L Soda 15 The dyeing process curve is shown in Figure 5. 2.2 Dyeing process conductivity The water conductivity changes at each stage of dyeing are shown in Figure 6. Can be seen from Figure 6. In the pre-treatment oxygen bleaching stage, the conductivity was low: After the beginning of the dyeing, the conductivity gradually increased. With the addition of Yuan Mingfen, the electrical conductivity increased rapidly. When all the soda is added, the conductivity reaches a peak value. It can be seen that Yuanmingfen and soda ash are the main factors that cause the increase of the conductivity of wastewater. Third, an effective method to reduce the conductivity of wastewater After the dyeing wastewater enters the wastewater treatment plant, it is usually treated with biochemical and physicochemical methods before further treatment. (The dyeing wastewater is precipitated and filtered through a valveless filter basin after reaching the discharge standard, and the suspended matter and turbidity are removed. The chromaticity is appropriately reduced. Called depth treatment). Wastewater treatment results are shown in Table 2. The basic process of wastewater treatment is: Hydrolysis acidification (anaerobic) _+ contact oxidation _+ precipitation-air flotation-clarification over a valveless filter. Table 2 shows the changes in the water quality of the various processes of sewage treatment. As can be seen, with the sewage into the various processing steps. The pH, color, turbidity, and COD values ​​of the wastewater decrease gradually. Only hardness and conductivity are always within a certain range of values. There is basically no downward trend. This shows that. Biochemical, physical, and advanced treatments cannot remove metal ions from water. In order to analyze the indicators of metal ions in the waste water. Several water quality conditions were measured and compared. The results are shown in Table 3. It can be seen from Table 3 that the conductivity is from 240 p. The s/cm rises to 2 650 ̈s/cm, the hardness change is not obvious. Sulfate and soluble total solids increased by more than 20 times. This shows that the conductivity of wastewater has a direct relationship with the level of sulfate and dissolved total solids in water. It can also be understood that excessive sulfate and soluble total solids are the main reasons leading to high conductivity of wastewater. Sulfate and dissolved total solids in wastewater are high. It shows that there are many metal ions in the water and the salt content is high. Therefore, the uniformity of the dyeing of salt-sensitive dyes is directly affected. Also known from Table 2 and Table 3. The current sewage treatment method used by the bleaching and dyeing plants. That is, biochemical, physicochemical, and advanced treatments can not effectively reduce the conductivity of dyeing wastewater. According to the test. The most effective way to reduce the conductivity of wastewater is to use reverse osmosis membranes. It can effectively remove metal ions in water. Its dialysate is low in hardness and low in electrical conductivity. Color, suspended solids and other indicators are in line with the requirements of high-quality water. Can meet the dyeing requirements of various varieties: At the same time in the case of a reasonable proportion of reuse. The concentration of the effluent concentrate can also meet the first-grade emission standard in GB 4287--92. See Table 4. Fourth, the conclusion Reverse osmosis membrane treatment can effectively reduce the conductivity of dyeing wastewater. And the indicators are in line with the bleaching and dyeing production water requirements. Suitable for wastewater reuse projects. However, due to the higher investment in the project, the current cost per ton of water needs about 2 yuan, plus the previous process to meet the standard sewage treatment fee of 2 yuan per ton, the total cost of about 4 yuan per ton. This is the case when the current water price is low. It cannot be widely accepted yet. But with the increasing shortage of water resources. Water saving work is imperative. The reverse osmosis membrane process is also constantly improving. With continuous improvement, the cost will inevitably drop, and the process will gradually be adopted. At the same time, some other methods can also be considered to reduce the cost of water treatment. a. Substitution of alkali agent for soda ash can reduce waste Water conductivity In the dyeing process of the active material, an alkali agent is used instead of the same color of the soda ash. The dosage is only 1/8~1/10 of the amount of soda ash. It has been proved that the conductivity of the waste liquid with the same color as the alkaline agent is much lower than that of the waste liquid with the solid color. The low conductivity liquid waste can be applied to the dyeing of polyester fibers after biochemical, physical and advanced treatment. b. Research and development of salt-free dyeing process Salt-free staining is a new dyeing process that is being developed and found from a large number of experiments. The conductivity of waste water produced by salt-free dyeing is 80%-90% lower than salt dyeing. Wastewater is treated with ceramic membranes or other simple treatment methods. Can achieve the activity of dyeing water requirements. Greatly reduced processing costs. Author: Chang to true Don't know what to wear at home? SHAOXING LIDONG TRADING CO.,LTD , https://www.lidonggarments.com
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