Fabric Products,Fabric Information,Fabric Factories,Fabric Suppliers Fabric News Surprising! The treatment effects and costs of many printing and dyeing wastewater plants are not ideal! During the epidemic, it is even more necessary to reduce costs and increase efficiency!

Surprising! The treatment effects and costs of many printing and dyeing wastewater plants are not ideal! During the epidemic, it is even more necessary to reduce costs and increase efficiency!



Affected by the epidemic, overseas orders have shrunk, and many printing and dyeing factories have under-operated production, resulting in a reduction in sewage volume. The sewage treatment system is operating …

Affected by the epidemic, overseas orders have shrunk, and many printing and dyeing factories have under-operated production, resulting in a reduction in sewage volume. The sewage treatment system is operating at a light load, which is just suitable for some modifications or adjustments; production management is not particularly busy, and the boss Or managers can spare more energy to reorganize the sewage treatment system to see how to reduce sewage operating costs or improve treatment capacity through transformation, so as to better cope with production recovery or growth after the epidemic is over, and enhance the overall competition of dyeing plants. force. In this article, we will share with you how to perform performance evaluation on the existing printing and dyeing wastewater treatment system, hoping to help you.

How do you know whether your sewage treatment system is operating normally? Because the water quality is different, the evaluation is relatively complicated, but we have selected common ones to share with you. You can evaluate them in terms of removal rate and operating costs, or you can conduct self-examinations against common problems.

Removal rate and operating cost

Different fabrics or different materials Whether polyester, cotton, nylon, nylon or blended yarn, the printing and dyeing production process consists of pre-treatment, dyeing, printing and finishing. Part of the pre-treatment sewage and high-concentration printing sewage need to be separated separately, and other comprehensive sewage can be mixed and processed together.

1. Removal rate

Comprehensive sewage COD is between 0~2500mg /L (more common), it is possible to use full biochemical treatment (that is, there is basically no or less chemical dosing in the pre-chemical treatment, and the “anaerobic + aerobic” process is mainly used to reduce the cost of sewage dosing and sludge quantity). That is to say, when the COD of your sewage is below 2500mg/L, there is no oil in the sewage, the temperature is below 40°C, the PH value is between 6 and 9, and there are not many impurities suspended in the sewage, under normal circumstances, “disgusting” The removal rate of the “oxygen” process section can reach 30~50%, and the removal rate of the “aerobic” process section can reach 70~90%. In terms of the total biochemical treatment effect (anaerobic + aerobic), the total removal rate of COD The rate should be 80-90%. When the maximum COD of the incoming water is 2500mg/L, with a properly designed “anaerobic + aerobic” system, the COD of the biochemical effluent can reach 250-500mg/L. Those using soluble dyes in printing and dyeing production, such as reactive, acidic, etc., have a higher sewage removal rate; those using insoluble dyes, such as disperse dyes, have a lower sewage removal rate. You can judge the treatment effect of this process section based on the system water inlet and outlet indicators of each section. After biochemical sewage passes through the “coagulation and tertiary sedimentation tank” after the secondary sedimentation tank, the COD of the effluent can generally be stably below 150mg/L. Of course, the lower the COD of the incoming water, the lower the outlet water.

You can use this reference removal rate to evaluate the treatment effect of your own sewage plant. If it is too much lower than the reference removal rate, it means that the design/equipment of this section is not done well. Or the operation management is not done well and needs to be optimized to improve the removal rate.

2. Operating costs

Under the same water inlet conditions , under the premise that biochemical treatment can function normally, the cost of chemicals for the operation of the sewage treatment system (excluding the cost of pre-treatment and separate treatment of membrane concentrated water, or additional costs such as antimony removal and denitrification) generally does not exceed 1.5 yuan/ton of water. Another important reference indicator is the amount of sludge. The amount of sludge produced per 1,000 tons of sewage (60% moisture content) should not be higher than 3 tons (excluding sludge generated by acid precipitation of concentrated water). If the chemical fee is too high or the sludge volume is too much higher than the reference value, it is necessary to check whether the physical and chemical treatment is over-dosed and whether the biochemical system is not effective enough. Because the amount of sludge produced by biochemical treatment is small, the amount of sludge produced by the physical and chemical system is large. The cost of processing printing and dyeing sludge is increasing year by year. Managing the amount of sludge is one of the ways to effectively reduce the cost of processing. In addition, it is perfectly fine to press the printing and dyeing sludge to a moisture content of 60%. If the moisture content of your sludge is higher than this indicator, it will also cause the amount of sludge to increase. This is a waste of money and should be managed well.

The operation of terminal recycled water can also reflect the effectiveness of the sewage treatment section. Generally speaking, if the biochemical system is running well, the color of the secondary sedimentation water is relatively moderate, with a light tea color. If it is used for decolorization and reuse, adding powdered activated carbon or decolorizing agent usually at 100-200ppm can meet the reuse color requirements. , the cost is relatively moderate. If the color of the secondary sedimentation water is relatively dark and the effect of decolorization and reuse is not good or the cost is high, you need to check whether the biochemical process is not done well, especially in the anaerobic section (which contributes greatly to decolorization); There is a situation where iron ions or PTA and other components remain in the secondary sedimentation water. This color cannot be removed by activated carbon and other methods. If decolorization is necessary for reuse, you need to make adjustments and add less or no iron-containing agents, or Remove the concentrated water from the alkali containing PTA.

Similar to decolorization and reuse, the operation of the membrane reuse system can also reflect the effectiveness of the sewage treatment section. Under the premise that the water inlet of the membrane system meets the standard and is operated properly, the cleaning cycle of the double-membrane system should be 10-30 days/time, and the replacement cycle is 3 years/time. If the cleaning is too frequent, the membrane life will be significantly shorter than expected. In addition to the membrane itself, For quality issues, you also need to check whether the biochemistry is not done well, or the pre-treatment agent is not added appropriately, or the residue of pre-treatment and printing paste can easily block the film. These factors must be checked.Give it a try.

Summary: Anaerobic removal rate, aerobic removal rate, overall biochemical system removal rate, physical and chemical dosage, decolorization reuse effect and cost, membrane reuse system operation status, all It is the basis for you to evaluate whether your sewage treatment system is within the normal range. If so, congratulations, it means that your sewage treatment system has reasonable technology and good management. If not, it means that there are certain deviations in the overall design, and there is room for cost reduction and efficiency improvement. Especially if the operating cost is obviously high, it must be reduced. If the cost of one ton of water can be reduced by 0.5 yuan, a printing and dyeing factory with a sewage capacity of 2,000-10,000 tons/day can save 300,000-1.5 million yuan a year.

Frequently Asked Questions

In addition, we have summarized most of them Printing and dyeing sewage treatment systems that are not running well have these three common problems:

First, improper pretreatment. This pretreatment includes water quality and quantity adjustment, cooling, and removal of suspended solids and oil stains. We have seen many sewage treatment systems with insufficient adjustment capabilities and large fluctuations in water quality. All water can only be discharged to the sewage treatment system, which will put great pressure on the sewage treatment system. In some sewage treatment systems, the water quality fluctuates greatly, so air flotation is used to reduce the load and prevent the biochemical system from being overwhelmed. We suggest that if your regulating pool capacity is insufficient and the status quo cannot be changed, you should grid the regulating pool according to the production situation and store some water with high concentration separately. This will also bring unexpected benefits. In some pretreatments, suspended impurities are not properly removed, which blocks the cooling tower and causes a series of problems. Good pretreatment is to adjust the water quality well, not to fluctuate too much, remove large suspended solids and oil stains, adjust the PH value, and adjust the temperature well. These are actually easy to do. Provide a suitable water quality for the biochemical system, and do not let the biochemical system do things it cannot bear.

Second, the hydrolysis/anaerobic design is not good. We have seen too many cases of hydrolytic anaerobic operation failure. Many hydrolytic anaerobic tanks have become sludge sedimentation tanks. Managers have no concept of sludge discharge. Many operators are curious: Do hydrolytic anaerobic tanks still need to discharge sludge? There are also many hydrolysis anaerobic tanks with unreasonable mixing designs. After using a few submersible mixers, I feel that everything is fine. They didn’t know that the entire pool was stirred around the submersible mixer, and there was no movement in other locations. Many hydrolysis anaerobic tanks in sewage treatment systems only have a COD removal rate of 10 to 20%, which they think is normal. In fact, this is abnormal. A good hydrolysis anaerobic system generally has a removal rate of 30-50%. The hydrolysis anaerobic system should be able to improve the biochemical properties of sewage by more than 30% and should be able to undertake the role of COD degradation. Can significantly reduce sludge production. In actual projects, we will even discharge the sludge produced by the aerobic system after nutrient deployment into the hydrolysis anaerobic tank to re-digest the sludge and achieve the purpose of minimizing sludge discharge.

Third, the highly concentrated water is not treated well. The sewage produced in the pre-printing and dyeing treatment process includes desizing sewage, alkali reduction sewage or cooking sewage. At present, the general treatment method for alkali-reduced sewage is to separate the pressed mud with acid, add alkali to adjust the pH value, and then mix it into the comprehensive sewage treatment system. The general treatment method for desizing sewage is to add a large amount of chemicals for sedimentation pretreatment, and then mix it into the comprehensive sewage treatment system. The key problem is that the above method has high cost of chemicals and a large amount of sludge, and this water is mixed into the comprehensive sewage, making the overall sewage treatment much more difficult. In addition, high salt content, PVA/PTA and other components in concentrated water are detrimental to the operation of the recycling membrane.

Our philosophy is that pre-treatment sewage should be treated with efficient anaerobic processes, which can greatly improve the treatment effect and reduce treatment costs. One of our customers is a sofa printing and dyeing enterprise. The pre-treatment section produces 1,000 tons of sewage every day, with COD as high as 11,000 mg/L, which is mainly desizing (starch, modified starch and PVA) and alkali reduction sewage. We adjust the PH value of the wastewater to 9 and enter the efficient anaerobic design we designed. The COD of the effluent can be stabilized below 2000mg/L. After separate aerobic treatment of this wastewater and the use of a coagulation final sedimentation tank, the effluent can reach the discharge standard of less than 200.

We also have a customer who makes suede. There are 400 tons of alkali-reduced sewage every day, and the COD is as high as about 15,000 mg/L. We use carbon dioxide to adjust the PH value to 12. It directly enters the high-efficiency anaerobic system, and the effluent COD is below 2500mg/L, which greatly reduces the load of sewage. Moreover, the entire anaerobic process has no odor and the operating cost is also very low.

Compared with the conventional concentrated water treatment process, using anaerobic ideas, it is possible to reduce the treatment cost of one ton of concentrated water by 1-3 yuan. .

In addition to the aspects listed above, there are of course other factors that lead to unsatisfactory operation of the sewage treatment system, so I will not list them one by one. In addition, you can also check the operation of your own sewage treatment system by comparing it with sewage cases similar to yours. The sewage treatment system must operate well to ensure production; at the same time, cost control must be reasonable to avoid wasting money. In the current poor economic environment, making some cost-reducing and efficiency-increasing transformations to the sewage treatment plant will make it more competitive and increase efficiency after the epidemic is over.

At this moment, some cost-reducing and efficiency-increasing improvements to the sewage treatment plant will make it more competitive and increase efficiency after the epidemic is over. </p

This article is from the Internet, does not represent Composite Fabric,bonded Fabric,Lamination Fabric position, reproduced please specify the source.https://www.tradetextile.com/archives/36684

Author: clsrich

 
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