Efficient treatment method and system for high COD wastewater of polyester resin for powder coating

Abstract

The application discloses a kind of powder coating polyester resin high COD waste water efficient treatment method and system, belong to the wastewater treatment field in high molecular synthesis process, the present application is realized by phase separation using secondary chemical extraction, delamination and drainage mode, remove a part of long-chain organic dihydric alcohol and other raw materials, using high-low liquid level drainage is realized, after delamination, organic phase is treated by rectification to obtain the raw material of polyester synthesis can be recycled for the synthesis of polyester resin, after rectification, organic extraction solvent is continuously used for next batch wastewater extraction treatment;After delamination, water phase is treated by electrochemical flocculation in electrocoagulation tank, by means of special preparation of composite strain, biochemical anaerobic treatment is carried out, through conventional biochemical treatment process such as aerobic tank, sedimentation tank, finally, the COD of effluent is basically below 3000mg / L, which can directly meet the discharge requirements of conventional wastewater treatment plant for subsequent conventional biochemical treatment.The application has the advantages of simple process realization, low comprehensive cost, high treatment efficiency and the like.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology in polymer synthesis processes, specifically relating to an efficient treatment method and system for high COD wastewater from polyester resin used in powder coatings. Background Technology

[0002] Powder coatings, as a new type of environmentally friendly coating, have seen rapid development in recent years due to their solvent-free, 100% film-forming properties, and advantages such as being solvent-free, pollution-free, recyclable, environmentally friendly, and saving energy and resources. While there are many types of powder coatings, the film-forming material in mainstream products is primarily polyester resin. For example, in outdoor weather-resistant powder coatings, polyester resin accounts for over 90% of the organic film-forming material. In recent years, the production of polyester resins for powder coatings has grown rapidly. Because powder coatings have high requirements for weather resistance, water resistance, and flexibility, their synthesis raw materials are mainly diacids and long-chain diols, such as 1,3-cyclohexanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol. In the later stages of polyester resin synthesis, due to the large molecular weight of the resin, the reaction temperature reaches approximately 240-260℃, requiring a high-vacuum system for vacuum polycondensation. This results in some diols and diacids being distilled off during the high-temperature vacuum polycondensation process in the later stages of polyester resin synthesis and entering the esterification water. This is the main reason for the high COD (Chemical Oxygen Demand) in wastewater from polyester resin used in powder coatings. The collected wastewater from polyester resin used in powder coatings has a COD exceeding 100,000 mg / L, while the COD of general wastewater from polyester resin used in powder coatings is generally between 80,000 and 100,000 mg / L. However, the biological treatment of wastewater in chemical industrial parks and municipal wastewater treatment plants can generally only accept water sources with a COD of around 3,000 mg / L.

[0003] To meet emission requirements, most manufacturers of polyester resins for powder coatings currently dilute the COD of their wastewater from over 80,000 mg / L to around 3,000 mg / L by directly adding water. This dilution ratio often reaches about 30 times. This not only greatly increases the amount of wastewater to be treated and the treatment costs for manufacturers, but also, because it far exceeds the wastewater treatment capacity of downstream chemical industrial park wastewater treatment plants, often necessitates mandatory production restrictions by limiting the discharge of upstream polyester resin wastewater. This severely restricts the production capacity of manufacturers and is extremely detrimental to the development of the polyester resin industry for powder coatings. Furthermore, the organic COD in the wastewater from polyester resin used in powder coatings is too high, reaching over 80,000 mg / L. If such high-COD wastewater is directly used for biological treatment, even if special COD bacteria are cultivated, the cost of such COD bacteria is extremely high. Moreover, the high COD of the wastewater not only slows down the biological treatment process but also leads to a high mortality rate of the COD bacteria required for biological treatment, ultimately resulting in a significant increase in the cost of biological treatment and making it difficult to achieve large-scale treatment of high-COD wastewater from polyester resin used in powder coatings. Summary of the Invention

[0004] Therefore, the present invention provides a method and system for the efficient treatment of high COD wastewater from polyester resin used in powder coatings, so as to achieve efficient and large-scale treatment of high COD wastewater from polyester resin used in powder coatings.

[0005] The technical solution adopted by this invention to solve the technical problem is as follows:

[0006] This invention provides a highly efficient method for treating high-COD wastewater from polyester resin used in powder coatings, comprising the following steps:

[0007] (1) Pump the high COD wastewater of polyester resin for powder coating to the wastewater storage and conditioning tank, and adjust the pH value of the high COD wastewater of polyester resin for powder coating to 6-8.

[0008] (2) The high COD wastewater of polyester resin for powder coating and the primary extraction solvent are fed into the counter-extraction tank at a fixed speed, and the counter-extraction and mixing are carried out in the counter-extraction tank.

[0009] (3) The mixed solution after the counter-mixed extraction is transported to the extraction tank and the first stirrer is started to stir for 20-30 minutes; let it stand for 30-50 minutes to separate into layers. After the layers are completely separated, the first extraction solution is released through the drain hole of the extraction tank.

[0010] (4) Add secondary extraction solvent to the high COD wastewater of polyester resin for powder coating after one extraction to fully extract the organic matter and residual primary extraction solvent in the system; start the first stirrer and stir for 10-15 minutes; let it stand for 20-30 minutes to separate the layers, and after complete separation, release the secondary extraction solution through the drain hole of the extraction tank again.

[0011] (5) After merging the primary extraction solution and the secondary extraction solution, they are transported to the distillation tower for distillation treatment. At the same time, the high COD wastewater of the powder coating and polyester resin after secondary extraction is pumped to the electrocoagulation tank through the discharge valve of the extraction tank for electrochemical flocculation treatment. After the electrochemical flocculation treatment is completed, the supernatant in the electrocoagulation tank is discharged through the discharge hole of the electrocoagulation tank.

[0012] (6) Start the second agitator to stir the viscous flocs at the bottom of the electrocoagulation tank to disperse them fully, and use the sludge pump to transport the viscous flocs through the discharge valve of the electrocoagulation tank to the plate and frame filter press for filter pressing to separate the solid and liquid. Combine the clear liquid after filter pressing with the supernatant discharged from the electrocoagulation tank to obtain low COD wastewater. At the same time, the solid flocs after filter pressing are treated by solid waste incineration.

[0013] (7) The obtained low COD wastewater is transported to the anaerobic tank, treated with compound bacterial active liquid for degradation, and then treated in sequence through the aerobic tank and sedimentation tank before being discharged as clean water with COD below 3000 mg / L.

[0014] In a preferred embodiment, the primary extraction solvent is a mixture of propyl acetate and propyl ether, wherein the volume ratio of propyl acetate to propyl ether is 1:(1-1.5).

[0015] In a preferred embodiment, the mass ratio of the primary extraction solvent to the high COD wastewater from the polyester resin used in powder coating is 1:(95-100).

[0016] In a preferred embodiment, in step (2), the range of the fixed speed is: the mass ratio of the high COD wastewater of the polyester resin for powder coating to the primary extraction solvent is (95-100):1 within the same unit time.

[0017] In a preferred embodiment, the secondary extraction solvent is cyclohexane.

[0018] In a preferred embodiment, the mass ratio of the primary extraction solvent to the secondary extraction solvent is 1:(0.2-0.25).

[0019] In a preferred embodiment, the compound microbial active liquid contains the following components in weight percentage: Bacillus subtilis 37-45%, Lactobacillus 19-26%, Enterobacter ludwig verrucose 15-25%, Copper-loving bacteria 10-17%, Nitrifying bacteria 6-11%, and Aspergillus oryzae 2-5%.

[0020] As a preferred embodiment, the preparation method of the composite bacterial strain active liquid is as follows:

[0021] (a) Preparation of microbial complex strains;

[0022] Mix the bacterial strains evenly according to the following weight percentages: Bacillus subtilis 37-45%, Lactobacillus 19-26%, Enterobacter ludwig verrucose 15-25%, Copper-loving bacteria 10-17%, Nitrifying bacteria 6-11%, and Aspergillus oryzae 2-5%.

[0023] (b) The microbial compound strain, sucrose, wheat bran and water are mixed and stirred thoroughly to obtain a compound strain solution, with a mass ratio of 1:(5-10):(12-18):(5500-6000).

[0024] (c) Place the prepared compound bacterial culture solution under completely anaerobic conditions and seal it for 4-7 days; then place it under aerobic conditions for 3-5 days, during which aeration is carried out by aeration and oxygen supply, aeration once every 10-12 hours; then place it in a constant temperature incubator at 25-32℃ for 30-40 hours to obtain the compound bacterial culture active liquid.

[0025] This invention provides a high-efficiency treatment system for high-COD wastewater from polyester resin used in powder coatings, used to implement the aforementioned high-efficiency treatment method for high-COD wastewater from polyester resin used in powder coatings. The system includes:

[0026] Wastewater storage and equalization tank is used to store high COD wastewater from polyester resin used in powder coatings and to adjust the pH of the high COD wastewater from polyester resin used in powder coatings.

[0027] A flushing tank connected to a wastewater storage and equalization tank is provided. A primary extraction solvent is added to the flushing tank, and the high COD wastewater from polyester resin for powder coating is flushed and mixed in the flushing tank to obtain a mixed solution.

[0028] An extraction tank connected to a counter-coupling tank is used to perform primary and secondary extractions on the mixed solution after counter-coupling and mixing extraction.

[0029] A distillation column connected to the extraction cell is used to distill the combined liquid from the primary and secondary extraction processes.

[0030] The electrocoagulation tank connected to the extraction tank is used to electrochemically flocculate the high COD wastewater of polyester resin for powder coating after secondary extraction. The obtained viscous flocs are deposited at the bottom of the electrocoagulation tank, and the upper layer of the electrocoagulation tank is the supernatant.

[0031] A plate and frame filter press is connected to an electrocoagulation tank via a sludge pump. The sludge pump is used to transport viscous flocs from the bottom of the electrocoagulation tank to the plate and frame filter press, which is used to filter the viscous flocs to obtain a clear liquid.

[0032] An anaerobic tank, connected to a plate and frame filter press and an electrocoagulation tank respectively, combines the clarified liquid after filter pressing with the supernatant discharged from the electrocoagulation tank to obtain low COD wastewater. The low COD wastewater is then degraded in the anaerobic tank using a compound bacterial active liquid.

[0033] The aerobic tank connected to the anaerobic tank is used to further treat the wastewater after degradation treatment, so that the organic matter in the wastewater is decomposed into inorganic matter and pollutants are removed;

[0034] The sedimentation tank connected to the aerobic tank is used to further sedimentate the wastewater after the aerobic tank treatment to obtain clean water with a COD of less than 3000 mg / L.

[0035] In a preferred embodiment, the extraction tank is a stainless steel extraction tank, which is equipped with a first stirrer inside. An extraction tank inlet and an extraction tank discharge valve are respectively located on both sides of its bottom, and an extraction tank drain hole is provided on its side wall. The first stirrer is used to fully stir the mixed solution after counter-mixed extraction. The extraction tank inlet is used to input the mixed solution after counter-mixed extraction into the extraction tank. The extraction tank discharge valve is used to discharge the high-COD wastewater from the polyester resin for powder coatings after secondary extraction. The extraction tank drain hole is used to discharge the primary and secondary extraction solutions. There are multiple extraction tank drain holes, and the position of each extraction tank drain hole should correspond to different liquid levels in the extraction tank.

[0036] In a preferred embodiment, the electrocoagulation tank is equipped with an electrocoagulation unit and a second agitator. An electrocoagulation tank inlet and an electrocoagulation tank discharge valve are respectively located on its bottom sides, and an electrocoagulation tank drain hole is provided on its side wall. The electrocoagulation unit is used to perform electrochemical flocculation treatment, the second agitator is used to perform stirring during the electrochemical flocculation process, the electrocoagulation tank inlet is used to input high-COD wastewater from polyester resin used for powder coatings after secondary extraction, the electrocoagulation tank discharge valve is used to discharge viscous flocs, and the electrocoagulation tank drain hole is used to discharge the supernatant obtained after the electrochemical flocculation treatment. There are multiple electrocoagulation tank drain holes, and the position of each drain hole should correspond to a different liquid level in the electrocoagulation tank.

[0037] The beneficial effects of this invention are:

[0038] This invention discloses a highly efficient treatment method and system for high-COD wastewater from polyester resin used in powder coatings. The invention first employs a two-stage chemical extraction, stratification, and discharge method to achieve phase separation, removing some long-chain organic diols and other raw materials. This step significantly reduces COD, and the use of high and low liquid level discharge eliminates the need for power pumps and other equipment, resulting in low energy consumption. The stratified organic phase is then distilled to obtain raw materials for polyester synthesis, which can be recycled for polyester resin synthesis. The distilled organic extraction solvent is reused for the extraction treatment of the next batch of high-concentration polyester resin wastewater. The stratified aqueous phase undergoes electrochemical flocculation treatment in a specific electrocoagulation tank. After electrochemical flocculation, the COD of the wastewater is reduced to below 28,000 mg / L. Then, it undergoes anaerobic biological treatment using specially prepared composite bacteria, followed by conventional biological treatment processes such as aerobic tanks and sedimentation tanks. The final effluent COD is below 3,000 mg / L, directly meeting the discharge requirements of conventional wastewater treatment plants for subsequent conventional biological treatment.

[0039] This invention provides a targeted treatment for high-COD wastewater from existing polyester resins used in powder coatings. It can effectively reduce the COD index in the wastewater and has the advantages of simple process implementation, low overall cost, and high treatment efficiency. Attached Figure Description

[0040] Figure 1 The flowchart illustrates an efficient method for treating high-COD wastewater from polyester resin used in powder coatings, as provided by this invention.

[0041] Figure 2 This invention provides a structural block diagram of a high-efficiency treatment system for high-COD wastewater from polyester resin used in powder coatings.

[0042] Figure 3 This is a schematic diagram of the extraction cell.

[0043] Figure 4 This is a schematic diagram of the electrocoagulation cell.

[0044] In the diagram, 1. Wastewater storage and equalization tank; 2. Flushing tank; 3. Extraction tank; 301. First agitator; 302. Extraction tank discharge valve; 303. Extraction tank inlet; 304. Extraction tank drain hole; 4. Distillation column; 5. Electrocoagulation tank; 501. Second agitator; 502. Electrocoagulation unit; 503. Electrocoagulation tank inlet; 504. Electrocoagulation tank discharge valve; 505. Electrocoagulation tank drain hole; 6. Plate and frame filter press; 7. Anaerobic tank; 8. Aerobic tank; 9. Sedimentation tank; 10. Sludge pump. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to the accompanying drawings.

[0046] In a first aspect, the present invention provides an efficient method for treating high COD wastewater from polyester resin used in powder coatings.

[0047] See Figure 1 The present invention provides an efficient method for treating high-COD wastewater from polyester resin used in powder coatings, the specific implementation process of which is as follows:

[0048] This invention provides an efficient method for treating high-COD wastewater from polyester resin used in powder coatings, the specific implementation process of which is as follows:

[0049] (1) Pump the high COD wastewater of polyester resin for powder coating to wastewater storage and conditioning tank 1, and adjust the pH value of the high COD wastewater of polyester resin for powder coating to 6-8.

[0050] (2) The high COD wastewater of polyester resin for powder coating and the primary extraction solvent are transported to the counter-extraction tank 2 at a fixed speed, and the counter-extraction mixing is carried out in the counter-extraction tank 2.

[0051] The primary extraction solvent is preferably a mixture of propyl acetate and propyl ether, and the volume ratio of propyl acetate to propyl ether is preferably 1:(1-1.5).

[0052] The preferred mass ratio of the primary extraction solvent to the high COD wastewater from polyester resin used in powder coating is 1:(95-100).

[0053] The preferred range of the fixed speed is: within the same unit time, the mass ratio of the high COD wastewater of the polyester resin for powder coating to the primary extraction solvent is (95-100):1.

[0054] (3) The mixed solution after the counter-mixed extraction is transported from the extraction tank inlet 303 at the bottom of the extraction tank 3 to the extraction tank 3. After reaching the appropriate liquid level, the first stirrer 301 is started to stir for 20-30 minutes; it is left to stand for 30-50 minutes to separate into layers. After complete separation, the first extraction solution is released through the extraction tank drain hole 304.

[0055] (4) Add secondary extraction solvent to the high COD wastewater of polyester resin for powder coating after one extraction to fully extract the organic matter and residual primary extraction solvent in the system; start the first stirrer 301 and stir for 10-15 minutes; let it stand for 20-30 minutes to separate the layers, and after complete separation, release the secondary extraction solution through the extraction tank drain hole 304 again.

[0056] The preferred solvent for secondary extraction is cyclohexane, but it is not limited to this.

[0057] The preferred mass ratio of primary extraction solvent to secondary extraction solvent is 1:1.

[0058] (0.2-0.25).

[0059] (5) After merging the primary extraction solution and the secondary extraction solution, they are sent to the distillation column 4 for distillation treatment. The solvent after distillation can be recycled. At the same time, the high COD wastewater of polyester resin for powder coating after secondary extraction is pumped from the electrocoagulation tank inlet 503 at the bottom of the electrocoagulation tank 5 through the extraction tank discharge valve 302 to the electrocoagulation tank 5 for electrochemical flocculation treatment using the electrocoagulation unit 502. After the electrochemical flocculation treatment is completed, the supernatant in the electrocoagulation tank 5 is discharged through the electrocoagulation tank drain hole 505.

[0060] The anode of the electrocoagulation unit 502 is preferably an iron anode or an aluminum anode, the electrode spacing is preferably 1-1.5m, and the current density is preferably 40-45mA / cm². 2 The preferred electrochemical flocculation time is 40-50 min.

[0061] (6) Start the second agitator 501 to stir the viscous flocs at the bottom of the electrocoagulation tank to disperse them fully, and use the sludge pump 10 to transport the viscous flocs through the electrocoagulation tank discharge valve 504 to the plate and frame filter press 6 for filter pressing to separate solid and liquid. Combine the clear liquid after filter pressing with the supernatant discharged from the electrocoagulation tank to obtain low COD wastewater. At the same time, the solid flocs after filter pressing are treated by solid waste incineration.

[0062] (7) The obtained low COD wastewater is transported to the anaerobic tank 7, and after being degraded by the compound bacterial active liquid, it is then treated by conventional processes such as the aerobic tank 8 and the sedimentation tank 9. The discharged water has a COD of less than 3000 mg / L and can be discharged into the park's ordinary sewage treatment plant or the city's ordinary sewage treatment plant to achieve the final standard discharge treatment.

[0063] Among them, anaerobic tank 7 and aerobic tank 8 respectively used ordinary anaerobic activated sludge and aerobic activated sludge currently used in sewage treatment plants. Anaerobic tank 7 additionally used compound bacterial activated liquid to improve its degradation capacity. The activated sludge in anaerobic tank 7 and aerobic tank 8 were all from Huangshan City Huizhou District Shuangyi Environmental Engineering Co., Ltd.

[0064] Among them, sedimentation tank 9 can be used to remove suspended solids and other solids in water, and at the same time, the principle of sedimentation can be applied to remove activated sludge from the effluent of biological treatment.

[0065] The compound microbial active liquid contains the following components by weight percentage: Bacillus subtilis 37-45%, Lactobacillus 19-26%, Enterobacter ludwig verrucose 15-25%, Copper-loving bacteria 10-17%, Nitrifying bacteria 6-11%, and Aspergillus oryzae 2-5%.

[0066] The preparation method of the compound bacterial strain active solution is as follows:

[0067] (a) Preparation of microbial complex strains;

[0068] Mix the bacterial strains evenly according to the following weight percentages: Bacillus subtilis 37-45%, Lactobacillus 19-26%, Enterobacter ludwig verrucose 15-25%, Copper-loving bacteria 10-17%, Nitrifying bacteria 6-11%, and Aspergillus oryzae 2-5%.

[0069] (b) The microbial compound strain, sucrose, wheat bran and water are mixed and stirred thoroughly to obtain a compound strain solution, with a mass ratio of 1:(5-10):(12-18):(5500-6000).

[0070] (c) The prepared compound bacterial culture solution is sealed and cultured under completely anaerobic conditions for 4-7 days; then it is cultured under aerobic conditions for 3-5 days, with aeration provided every 10-12 hours; finally, it is placed in a constant temperature incubator at 25-32℃ for 30-40 hours to obtain the compound bacterial culture active liquid. This compound bacterial culture active liquid serves as the main bacterial strain in anaerobic tank 7 to degrade low-COD wastewater.

[0071] Secondly, the present invention provides a high-efficiency treatment system for high-COD wastewater from polyester resin used in powder coatings, which is used to achieve the aforementioned high-efficiency treatment method for high-COD wastewater from polyester resin used in powder coatings.

[0072] See Figure 2 The present invention provides a high-efficiency treatment system for high-COD wastewater from polyester resin used in powder coatings, which mainly includes:

[0073] Wastewater storage and equalization tank 1 is used to store high COD wastewater from polyester resin for powder coating and to adjust the pH of the high COD wastewater from polyester resin for powder coating.

[0074] A flushing tank 2 is connected to a wastewater storage and equalization tank. A primary extraction solvent is added to the flushing tank. The primary extraction solvent is used to flush and mix the high COD wastewater of polyester resin for powder coating in the flushing tank to obtain a mixed solution.

[0075] The extraction tank 3, connected to the counter-extraction tank, is used for primary and secondary extraction of the mixed solution after counter-extraction. The extraction tank 3 is preferably a stainless steel extraction tank, equipped with a first stirrer 301 inside. An extraction tank inlet 303 and an extraction tank discharge valve 302 are respectively located on both sides of its bottom, and an extraction tank drain hole 304 is provided on its side wall. The first stirrer 301 is used to thoroughly stir the mixed solution after counter-extraction. The extraction tank inlet 303 is used to input the mixed solution after counter-extraction into the extraction tank 3. The extraction tank discharge valve 302 is used to discharge the high-COD wastewater from the polyester resin for powder coatings after secondary extraction. The extraction tank drain hole 304 is used to discharge the primary and secondary extraction solutions. Multiple extraction tank drain holes 304 can be provided, and the position of each extraction tank drain hole 304 should correspond to different liquid levels in the extraction tank 3.

[0076] The distillation column 4, connected to the extraction cell, is used to distill the combined liquid after primary and secondary extraction.

[0077] An electrocoagulation tank 5, connected to the extraction tank 3, is used for electrochemical flocculation treatment of high-COD wastewater from polyester resin used in powder coatings after secondary extraction. The resulting viscous flocs are deposited at the bottom of the electrocoagulation tank 5, and the upper layer of the electrocoagulation tank 5 is the supernatant. The electrocoagulation tank 5 is equipped with an electrocoagulation unit 502 and a second stirrer 501. An electrocoagulation tank inlet 503 and an electrocoagulation tank discharge valve 504 are respectively located on both sides of its bottom, and an electrocoagulation tank drain hole 505 is provided on its side wall. The electrocoagulation unit 502 is used to achieve electrochemical flocculation treatment. The second stirrer 501 is used to perform stirring during the electrochemical flocculation process. The electrocoagulation tank inlet 503 is used to input high COD wastewater of polyester resin for powder coating after secondary extraction into the electrocoagulation tank 5. The electrocoagulation tank discharge valve 504 is used to discharge viscous flocs. The electrocoagulation tank drain hole 505 is used to discharge the supernatant obtained after the electrochemical flocculation process. The number of electrocoagulation tank drain holes 505 can be set to multiple, and the position of each electrocoagulation tank drain hole 505 should correspond to different liquid level positions in the electrocoagulation tank 5.

[0078] The plate and frame filter press 6 is connected to the electrocoagulation tank 5 via the sludge pump 10. The sludge pump 10 is used to transport the viscous flocs at the bottom of the electrocoagulation tank 5 to the plate and frame filter press 6. The plate and frame filter press 6 is used to filter the viscous flocs to obtain a clear liquid.

[0079] Anaerobic tank 7, which is connected to plate and frame filter press 6 and electrocoagulation tank 5 respectively, combines the clear liquid after filter press treatment with the supernatant discharged from electrocoagulation tank 5 to obtain low COD wastewater. The low COD wastewater is then degraded in anaerobic tank 4 using compound bacterial active liquid.

[0080] The aerobic tank 8, connected to the anaerobic tank 4, is used to further treat the wastewater after degradation treatment, so that the organic matter in the wastewater is decomposed into inorganic matter and pollutants are removed;

[0081] The sedimentation tank 9, which is connected to the aerobic tank 8, is used to further sediment the wastewater after the aerobic tank 8 treatment to obtain clean water with a COD of less than 3000 mg / L.

[0082] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0083] Example 1

[0084] A highly efficient method for treating high-COD wastewater from polyester resin used in powder coatings, the specific implementation process of which is as follows:

[0085] (1) Pump the high COD wastewater of polyester resin for powder coating to wastewater storage and conditioning tank 1 and adjust the pH value of the high COD wastewater of polyester resin for powder coating to 6.

[0086] (2) The primary extraction solvent (a mixture of propyl acetate and propyl ether, with a volume ratio of 1:1) and the high COD wastewater from polyester resin for powder coating are fed into the offset tank 2 at a mass ratio of 1:95 and at a fixed speed, and the offset mixing extraction is carried out in the offset tank 2.

[0087] (3) The mixed solution after the counter-mixed extraction is transported from the extraction tank inlet 303 at the bottom of the extraction tank 3 to the extraction tank 3. After reaching the appropriate liquid level, the first stirrer 301 is started and stirred for 20 minutes. After standing for 30 minutes to separate into layers, the extraction solution is released through the extraction tank drain hole 304.

[0088] (4) Add cyclohexane (the mass ratio of primary extraction solvent to cyclohexane is 1:0.2) to the high COD wastewater of polyester resin for powder coating after one extraction to fully extract the organic matter and residual primary extraction solvent in the system; start the first stirrer 301 and stir for 10 min; let it stand for 20 min to separate the layers, and after complete separation, release the secondary extraction solution through the extraction tank drain hole 304 again.

[0089] (5) After merging the primary and secondary extraction solutions, they are sent to distillation column 4 for distillation. The solvent after distillation can be recycled. At the same time, the high COD wastewater of the powder coating polyester resin after secondary extraction is pumped from the electrocoagulation tank inlet 503 at the bottom of the electrocoagulation tank 5 through the extraction tank discharge valve 302 to the electrocoagulation tank 5. The electrocoagulation unit 502 (the anode of the electrocoagulation unit 502 is an iron anode, the electrode spacing is 1m, and the current density is 40mA / cm) is used. 2 Electrochemical flocculation treatment was carried out for 40 minutes. After the electrochemical flocculation treatment was completed, the supernatant in the electrocoagulation tank 5 was released through the drain hole 505 of the electrocoagulation tank.

[0090] (6) Start the second agitator 501 to stir the viscous flocs at the bottom of the electrocoagulation tank to disperse them fully, and use the sludge pump 10 to transport the viscous flocs through the electrocoagulation tank discharge valve 504 to the plate and frame filter press 6 for filter pressing to separate solid and liquid. Combine the clear liquid after filter pressing with the supernatant discharged from the electrocoagulation tank to obtain low COD wastewater. At the same time, the solid flocs after filter pressing are treated by solid waste incineration.

[0091] (7) Preparation of compound microbial culture active solution: Mix the various microbial strains evenly according to the following weight percentages to prepare a compound microbial culture: Bacillus subtilis 37%, Lactobacillus 19%, Enterobacter ludwig's 15%, Copper-loving bacteria 10%, Nitrifying bacteria 6%, and Aspergillus oryzae 2%; Mix the compound microbial culture, sucrose, wheat bran, and water in a mass ratio of 1:5:12:5500 and stir thoroughly to obtain a compound microbial culture solution; Place the prepared compound microbial culture solution under completely anaerobic conditions and seal it for 4 days; then place it under aerobic conditions and culture it for 3 days, during which aeration is carried out by aeration treatment, aeration once every 12 hours; then place it in a constant temperature incubator and culture at 25℃ for 30 hours to obtain the compound microbial culture active solution.

[0092] The resulting low-COD wastewater is transported to anaerobic tank 7 (containing ordinary anaerobic activated sludge from a wastewater treatment plant, sourced from Huangshan City Huizhou District Shuangyi Environmental Engineering Co., Ltd.). After degradation treatment with the addition of compound bacterial active liquid, it then passes through conventional processes such as aerobic tank 8 (using ordinary aerobic activated sludge from a wastewater treatment plant, sourced from Huangshan City Huizhou District Shuangyi Environmental Engineering Co., Ltd.) and sedimentation tank 9. The discharged water has a COD of less than 3000 mg / L and can be discharged into the park's ordinary wastewater treatment plant or the city's ordinary wastewater treatment plant to achieve final discharge compliance.

[0093] Example 2

[0094] A highly efficient method for treating high-COD wastewater from polyester resin used in powder coatings, the specific implementation process of which is as follows:

[0095] (1) Pump the high COD wastewater of polyester resin for powder coating to wastewater storage and conditioning tank 1 and adjust the pH value of the high COD wastewater of polyester resin for powder coating to 8.

[0096] (2) The primary extraction solvent (a mixture of propyl acetate and propyl ether, with a volume ratio of 1:1.5) and the high COD wastewater from polyester resin for powder coating are fed into the counter-extraction tank 2 at a mass ratio of 1:100 and at this fixed rate, and the counter-extraction is carried out in the counter-extraction tank 2.

[0097] (3) The mixed solution after the counter-mixed extraction is transported from the extraction tank inlet 303 at the bottom of the extraction tank 3 to the extraction tank 3. After reaching the appropriate liquid level, the first stirrer 301 is started and stirred for 30 minutes. After standing for 50 minutes to separate into layers, the extraction solution is released through the extraction tank drain hole 304.

[0098] (4) Add cyclohexane (the mass ratio of primary extraction solvent to cyclohexane is 1:0.25) to the high COD wastewater of polyester resin for powder coating after one extraction to fully extract the organic matter and residual primary extraction solvent in the system; start the first stirrer 301 and stir for 15 min; let it stand for 30 min to separate the layers, and after complete separation, release the secondary extraction solution through the extraction tank drain hole 304 again.

[0099] (5) After merging the primary and secondary extraction solutions, they are sent to distillation column 4 for distillation. The solvent after distillation can be recycled. At the same time, the high COD wastewater of the powder coating polyester resin after secondary extraction is pumped from the electrocoagulation tank inlet 503 at the bottom of the electrocoagulation tank 5 through the extraction tank discharge valve 302 to the electrocoagulation tank 5. The electrocoagulation unit 502 (the anode of the electrocoagulation unit 502 is an aluminum anode, the electrode spacing is 1.5m, and the current density is 45mA / cm) is used. 2 Electrochemical flocculation treatment is carried out for 50 minutes. After the electrochemical flocculation treatment is completed, the supernatant in the electrocoagulation tank 5 is released through the drain hole 505 of the electrocoagulation tank.

[0100] (6) Start the second agitator 501 to stir the viscous flocs at the bottom of the electrocoagulation tank to disperse them fully, and use the sludge pump 10 to transport the viscous flocs through the electrocoagulation tank discharge valve 504 to the plate and frame filter press 6 for filter pressing to separate solid and liquid. Combine the clear liquid after filter pressing with the supernatant discharged from the electrocoagulation tank to obtain low COD wastewater. At the same time, the solid flocs after filter pressing are treated by solid waste incineration.

[0101] (7) Preparation of compound microbial culture active solution: Mix the various microbial strains evenly according to the following weight percentages to prepare a compound microbial culture: Bacillus subtilis 45%, Lactobacillus 26%, Enterobacter ludwig's 25%, Copper-loving bacteria 17%, Nitrifying bacteria vesiculosus 11%, and Aspergillus oryzae 5%; Mix the compound microbial culture, sucrose, wheat bran, and water in a mass ratio of 1:10:18:6000 and stir thoroughly to obtain a compound microbial culture solution; Place the prepared compound microbial culture solution under completely anaerobic conditions and seal it for 5 days; then place it under aerobic conditions and culture it for 5 days, during which aeration is carried out by aeration treatment, aeration once every 12 hours; then place it in a constant temperature incubator and culture at 32℃ for 40 hours to obtain the compound microbial culture active solution.

[0102] The resulting low-COD wastewater is transported to anaerobic tank 7 (containing ordinary anaerobic activated sludge from a wastewater treatment plant, sourced from Huangshan City Huizhou District Shuangyi Environmental Engineering Co., Ltd.). After degradation treatment with the addition of compound bacterial active liquid, it then passes through conventional processes such as aerobic tank 8 (using ordinary aerobic activated sludge from a wastewater treatment plant, sourced from Huangshan City Huizhou District Shuangyi Environmental Engineering Co., Ltd.) and sedimentation tank 9. The discharged water has a COD of less than 3000 mg / L and can be discharged into the park's ordinary wastewater treatment plant or the city's ordinary wastewater treatment plant to achieve final discharge compliance.

[0103] Example 3

[0104] A highly efficient method for treating high-COD wastewater from polyester resin used in powder coatings, the specific implementation process of which is as follows:

[0105] (1) Pump the high COD wastewater of polyester resin for powder coating to wastewater storage and conditioning tank 1 and adjust the pH value of the high COD wastewater of polyester resin for powder coating to 7.

[0106] (2) The primary extraction solvent (a mixture of propyl acetate and propyl ether, with a volume ratio of 1:1.3) and the high COD wastewater from polyester resin for powder coating are fed into the offset tank 2 at a mass ratio of 1:98 and at this fixed rate, and the offset mixing extraction is carried out in the offset tank 2.

[0107] (3) The mixed solution after the counter-mixed extraction is transported from the extraction tank inlet 303 at the bottom of the extraction tank 3 to the extraction tank 3. After reaching the appropriate liquid level, the first stirrer 301 is started and stirred for 25 minutes. After standing for 40 minutes to separate into layers, the extraction solution is released through the extraction tank drain hole 304.

[0108] (4) Add cyclohexane (the mass ratio of primary extraction solvent to cyclohexane is 1:0.25) to the high COD wastewater of polyester resin for powder coating after one extraction to fully extract the organic matter and residual primary extraction solvent in the system; start the first stirrer 301 and stir for 13 min; let it stand for 25 min to separate the layers, and after complete separation, release the secondary extraction solution through the extraction tank drain hole 304 again.

[0109] (5) After merging the primary and secondary extraction solutions, they are sent to distillation column 4 for distillation. The solvent after distillation can be recycled. At the same time, the high COD wastewater of the powder coating polyester resin after secondary extraction is pumped from the electrocoagulation tank inlet 503 at the bottom of the electrocoagulation tank 5 through the extraction tank discharge valve 302 to the electrocoagulation tank 5. The electrocoagulation unit 502 (the anode of the electrocoagulation unit 502 is an iron anode, the electrode spacing is 1.3m, and the current density is 43mA / cm) is used. 2Electrochemical flocculation treatment was carried out for 45 minutes. After the electrochemical flocculation treatment was completed, the supernatant in the electrocoagulation tank 5 was released through the drain hole 505 of the electrocoagulation tank.

[0110] (6) Start the second agitator 501 to stir the viscous flocs at the bottom of the electrocoagulation tank to disperse them fully, and use the sludge pump 10 to transport the viscous flocs through the electrocoagulation tank discharge valve 504 to the plate and frame filter press 6 for filter pressing to separate solid and liquid. Combine the clear liquid after filter pressing with the supernatant discharged from the electrocoagulation tank to obtain low COD wastewater. At the same time, the solid flocs after filter pressing are treated by solid waste incineration.

[0111] (7) Preparation of compound microbial culture active solution: Mix the various microbial strains evenly according to the following weight percentages to prepare a compound microbial culture: Bacillus subtilis 41%, Lactobacillus 22.5%, Enterobacter ludwig's 20%, Copper-loving bacteria 13.5%, Nitrifying bacteria vesiculosus 8.5%, and Aspergillus oryzae 3.5%; Mix the compound microbial culture, sucrose, wheat bran, and water in a mass ratio of 1:7.5:15:5750 and stir thoroughly to obtain a compound microbial culture solution; Place the prepared compound microbial culture solution under completely anaerobic conditions and seal it for 6 days; then place it under aerobic conditions and culture it for 4 days, during which aeration is carried out by aeration treatment, aeration once every 12 hours; then place it in a constant temperature incubator and culture at 28℃ for 35 hours to obtain the compound microbial culture active solution.

[0112] The resulting low-COD wastewater is transported to anaerobic tank 7 (containing ordinary anaerobic activated sludge from a wastewater treatment plant, sourced from Huangshan City Huizhou District Shuangyi Environmental Engineering Co., Ltd.). After degradation treatment with the addition of compound bacterial active liquid, it then passes through conventional processes such as aerobic tank 8 (using ordinary aerobic activated sludge from a wastewater treatment plant, sourced from Huangshan City Huizhou District Shuangyi Environmental Engineering Co., Ltd.) and sedimentation tank 9. The discharged water has a COD of less than 3000 mg / L and can be discharged into the park's ordinary wastewater treatment plant or the city's ordinary wastewater treatment plant to achieve final discharge compliance.

[0113] Example 4

[0114] A highly efficient method for treating high-COD wastewater from polyester resin used in powder coatings, the specific implementation process of which is as follows:

[0115] (1) Pump the high COD wastewater of polyester resin for powder coating to wastewater storage and conditioning tank 1 and adjust the pH value of the high COD wastewater of polyester resin for powder coating to 6.5.

[0116] (2) The primary extraction solvent (a mixture of propyl acetate and propyl ether, with a volume ratio of 1:1.4) and the high COD wastewater from polyester resin for powder coating are fed into the counter-extraction tank 2 at a mass ratio of 1:99 and at this fixed rate, and the counter-extraction is carried out in the counter-extraction tank 2.

[0117] (3) The mixed solution after the counter-mixed extraction is transported from the extraction tank inlet 303 at the bottom of the extraction tank 3 to the extraction tank 3. After reaching the appropriate liquid level, the first stirrer 301 is started and stirred for 40 minutes. After standing for 40 minutes to separate into layers, the extraction solution is released through the extraction tank drain hole 304.

[0118] (4) Add cyclohexane (the mass ratio of primary extraction solvent to cyclohexane is 1:0.2) to the high COD wastewater of polyester resin for powder coating after one extraction to fully extract the organic matter and residual primary extraction solvent in the system; start the first stirrer 301 and stir for 12 min; let it stand for 30 min to separate the layers, and after complete separation, release the secondary extraction solution through the extraction tank drain hole 304 again.

[0119] (5) After merging the primary and secondary extraction solutions, they are sent to distillation column 4 for distillation. The solvent after distillation can be recycled. At the same time, the high COD wastewater of the powder coating polyester resin after secondary extraction is pumped from the electrocoagulation tank inlet 503 at the bottom of the electrocoagulation tank 5 through the extraction tank discharge valve 302 to the electrocoagulation tank 5. The electrocoagulation unit 502 (the anode of the electrocoagulation unit 502 is an iron anode, the electrode spacing is 1.3m, and the current density is 43mA / cm) is used. 2 Electrochemical flocculation treatment was carried out for 45 minutes. After the electrochemical flocculation treatment was completed, the supernatant in the electrocoagulation tank 5 was released through the drain hole 505 of the electrocoagulation tank.

[0120] (6) Start the second agitator 501 to stir the viscous flocs at the bottom of the electrocoagulation tank to disperse them fully, and use the sludge pump 10 to transport the viscous flocs through the electrocoagulation tank discharge valve 504 to the plate and frame filter press 6 for filter pressing to separate solid and liquid. Combine the clear liquid after filter pressing with the supernatant discharged from the electrocoagulation tank to obtain low COD wastewater. At the same time, the solid flocs after filter pressing are treated by solid waste incineration.

[0121] (7) Preparation of compound microbial culture active solution: Mix the various microbial strains evenly according to the following weight percentages to prepare a compound microbial culture: Bacillus subtilis 38%, Lactobacillus 25%, Enterobacter ludwig's 20%, Copper-loving bacteria 15%, Nitrifying bacteria vesiculosus 10%, and Aspergillus oryzae 5%; Mix the compound microbial culture, sucrose, wheat bran, and water in a mass ratio of 1:8:17:5850 and stir thoroughly to obtain a compound microbial culture solution; Place the prepared compound microbial culture solution under completely anaerobic conditions and seal it for 7 days; then place it under aerobic conditions and culture it for 4 days, during which aeration is carried out by aeration treatment, aeration once every 12 hours; then place it in a constant temperature incubator and culture at 28℃ for 35 hours to obtain the compound microbial culture active solution.

[0122] The resulting low-COD wastewater is transported to anaerobic tank 7 (containing ordinary anaerobic activated sludge from a wastewater treatment plant, sourced from Huangshan City Huizhou District Shuangyi Environmental Engineering Co., Ltd.). After degradation treatment with the addition of compound bacterial active liquid, it then passes through conventional processes such as aerobic tank 8 (using ordinary aerobic activated sludge from a wastewater treatment plant, sourced from Huangshan City Huizhou District Shuangyi Environmental Engineering Co., Ltd.) and sedimentation tank 9. The discharged water has a COD of less than 3000 mg / L and can be discharged into the park's ordinary wastewater treatment plant or the city's ordinary wastewater treatment plant to achieve final discharge compliance.

[0123] Comparative Example 1

[0124] The other aspects are the same as in Example 3, except that in Comparative Example 1, extraction tank 3 is not used for extraction.

[0125] Comparative Example 2

[0126] The rest is the same as in Example 3, except that in Comparative Example 2, the electrocoagulation tank 5 is not used for electrocoagulation treatment.

[0127] Comparative Example 3

[0128] The rest is the same as in Example 3, except that in Comparative Example 3, only conventional ordinary anaerobic bacteria activated sludge is used in the biochemical treatment stage of anaerobic tank 7, and no compound bacterial activated liquid is used.

[0129] Experimental Example 1: COD Test

[0130] The test method is as follows: wastewater from the production of polyester resin for powder coatings collected from different batches of Huangshan Xiangrong New Materials Co., Ltd. was tested and its COD value was tested to be the original COD value; then the wastewater was treated according to Examples 1-4 and Comparative Examples 1-3 respectively, and the COD value of the effluent from the main links was tested. The test results are shown in Table 1 (COD unit is mg / L).

[0131] Table 1. COD test results of Examples 1-4 and Comparative Examples 1-3

[0132]

[0133] As shown in Table 1, Comparative Examples 1 and 2, respectively, did not employ the specific extraction and electrocoagulation steps of this invention, resulting in excessively high COD in the wastewater before biological treatment. This significantly reduced the effectiveness of the biological treatment, and the final effluent COD was too high to meet the requirements. Comparative Example 3 used anaerobic bacteria currently used in ordinary wastewater treatment plants to replace the specially selected, highly tolerant composite bacteria of this invention. While the anaerobic bacteria used in ordinary wastewater treatment plants are low-cost, they have poor tolerance and are only suitable for wastewater systems with COD below 3000 mg / L. Their activity significantly decreases in wastewater with COD exceeding 5000 mg / L, and this decrease becomes more pronounced with increasing COD concentration. Since the wastewater entering the biological treatment stage of this invention generally has a COD above 20000 mg / L, without the enhanced use of the specially selected, highly tolerant composite bacteria of this invention, it is difficult to achieve efficient degradation in the process of this invention using only ordinary conventional anaerobic bacteria activated sludge.

[0134] This invention employs a specific process combination and equipment to efficiently treat high-COD wastewater generated during the synthesis of polyester resin for powder coatings without the need for dilution with tap water. The final effluent COD can reach 3000 mg / L, achieving sustainable discharge without increasing wastewater volume. Compared to traditional methods of reducing wastewater COD by diluting with tap water, this invention indirectly increases the production capacity of polyester resin manufacturers by three times, resulting in significant economic and social benefits.

[0135] This invention discloses a highly efficient treatment method and system for high-COD wastewater from polyester resin used in powder coatings. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The product of this invention has been described through preferred embodiments, and those skilled in the art will clearly be able to modify or appropriately change and combine the product described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

Claims

1. A highly efficient method for treating high-COD wastewater from polyester resin used in powder coatings, characterized in that, Includes the following steps: (1) Pump the high COD wastewater of polyester resin for powder coating to the wastewater storage and conditioning tank, and adjust the pH value of the high COD wastewater of polyester resin for powder coating to 6-8. (2) The high COD wastewater of polyester resin for powder coating and the primary extraction solvent are transported to the counter-extraction tank at a fixed speed, and the counter-extraction and mixing are carried out in the counter-extraction tank. (3) The mixed solution after the counter-mixed extraction is transported to the extraction tank and the first stirrer is started to stir for 20-30 minutes; let it stand for 30-50 minutes to separate into layers. After the layers are completely separated, the first extraction solution is released through the drain hole of the extraction tank. (4) Add secondary extraction solvent to the high COD wastewater of polyester resin for powder coating after one extraction to fully extract the organic matter and residual primary extraction solvent in the system; start the first stirrer and stir for 10-15 minutes; let it stand for 20-30 minutes to separate the layers, and after complete separation, release the secondary extraction solution through the drain hole of the extraction tank again. (5) After merging the primary extraction solution and the secondary extraction solution, they are transported to the distillation tower for distillation treatment. At the same time, the high COD wastewater of the powder coating and polyester resin after secondary extraction is pumped to the electrocoagulation tank through the discharge valve of the extraction tank for electrochemical flocculation treatment. After the electrochemical flocculation treatment is completed, the supernatant in the electrocoagulation tank is discharged through the discharge hole of the electrocoagulation tank. (6) Start the second agitator to stir the viscous flocs at the bottom of the electrocoagulation tank to disperse them fully, and use the sludge pump to transport the viscous flocs through the discharge valve of the electrocoagulation tank to the plate and frame filter press for filter pressing to separate the solid and liquid. Combine the clear liquid after filter pressing with the supernatant discharged from the electrocoagulation tank to obtain low COD wastewater. At the same time, the solid flocs after filter pressing are treated by solid waste incineration. (7) The obtained low COD wastewater is transported to an anaerobic tank, treated with a compound microbial active liquid for degradation, and then treated in sequence through an aerobic tank and a sedimentation tank to discharge clean water with COD below 3000 mg / L; the compound microbial active liquid contains the following components in weight percentage: Bacillus subtilis 37-45%, Lactobacillus 19-26%, Ludwig's Enterobacter 15-25%, Copper-loving bacteria 10-17%, Nitrifying Bacillus vesiculosus 6-11% and Aspergillus oryzae 2-5%.

2. The efficient treatment method for high COD wastewater from polyester resin used in powder coatings according to claim 1, characterized in that, The primary extraction solvent is a mixture of propyl acetate and propyl ether, wherein the volume ratio of propyl acetate to propyl ether is 1:(1-1.5).

3. The method for efficient treatment of high-COD wastewater from polyester resin used in powder coatings according to claim 1, characterized in that, The mass ratio of the primary extraction solvent to the high COD wastewater from the polyester resin used in powder coating is 1:(95-100).

4. The efficient treatment method for high COD wastewater from polyester resin used in powder coatings according to claim 1, characterized in that, In step (2), the range of the fixed speed is: within the same unit time, the mass ratio of the high COD wastewater of the polyester resin for powder coating to the primary extraction solvent is (95-100):

1.

5. The efficient treatment method for high COD wastewater from polyester resin used in powder coatings according to claim 1, characterized in that, The solvent for the secondary extraction is cyclohexane.

6. The efficient treatment method for high COD wastewater from polyester resin used in powder coatings according to claim 1, characterized in that, The mass ratio of the primary extraction solvent to the secondary extraction solvent is 1:(0.2-0.25).

7. The efficient treatment method for high COD wastewater from polyester resin used in powder coatings according to claim 1, characterized in that, The preparation method of the compound bacterial strain active liquid is as follows: (a) Preparation of microbial complex strains; Mix the bacterial strains evenly according to the following weight percentages: Bacillus subtilis 37-45%, Lactobacillus 19-26%, Ludwig's Enterobacter 15-25%, Copper-loving bacteria 10-17%, Nitrosobacterium vesiculosum 6-11%, and Aspergillus oryzae 2-5%; (b) The microbial compound strain, sucrose, wheat bran and water are mixed and thoroughly stirred and dispersed in a mass ratio of 1:(5-10):(12-18):(5500-6000) to obtain a compound strain solution. (c) Place the prepared compound bacterial culture solution under completely anaerobic conditions and seal it for 4-7 days; then place it under aerobic conditions for 3-5 days, during which aeration is carried out by aeration and oxygen supply, aeration once every 10-12 hours; then place it in a constant temperature incubator at 25-32℃ for 30-40 hours to obtain the compound bacterial culture active liquid.

8. A high-efficiency treatment system for high-COD wastewater from polyester resin used in powder coatings, used to implement the high-efficiency treatment method for high-COD wastewater from polyester resin used in powder coatings as described in any one of claims 1 to 7, characterized in that, The system includes: Wastewater storage and equalization tank is used to store high COD wastewater from polyester resin used in powder coatings and to adjust the pH of the high COD wastewater from polyester resin used in powder coatings. A flushing tank connected to a wastewater storage and equalization tank is provided. A primary extraction solvent is added to the flushing tank, and the high COD wastewater from polyester resin for powder coating is flushed and mixed in the flushing tank to obtain a mixed solution. An extraction tank connected to a counter-coupling tank is used to perform primary and secondary extractions on the mixed solution after counter-coupling and mixing extraction. A distillation column connected to the extraction cell is used to distill the combined liquid from the primary and secondary extraction processes. The electrocoagulation tank connected to the extraction tank is used to electrochemically flocculate the high COD wastewater of polyester resin for powder coating after secondary extraction. The obtained viscous flocs are deposited at the bottom of the electrocoagulation tank, and the upper layer of the electrocoagulation tank is the supernatant. A plate and frame filter press is connected to an electrocoagulation tank via a sludge pump. The sludge pump is used to transport viscous flocs from the bottom of the electrocoagulation tank to the plate and frame filter press, which is used to filter the viscous flocs to obtain a clear liquid. An anaerobic tank, connected to a plate and frame filter press and an electrocoagulation tank respectively, combines the clarified liquid after filter pressing with the supernatant discharged from the electrocoagulation tank to obtain low COD wastewater. The low COD wastewater is then degraded in the anaerobic tank using a compound bacterial active liquid. The aerobic tank connected to the anaerobic tank is used to further treat the wastewater after degradation treatment, so that the organic matter in the wastewater is decomposed into inorganic matter and pollutants are removed; The sedimentation tank connected to the aerobic tank is used to further sedimentate the wastewater after the aerobic tank treatment to obtain clean water with a COD of less than 3000 mg / L.

9. The high-efficiency treatment system for high-COD wastewater from polyester resin used in powder coatings according to claim 8, characterized in that, The extraction tank is a stainless steel extraction tank, equipped with a first agitator inside. It has an extraction tank inlet and an extraction tank discharge valve on its bottom sides, and an extraction tank drain hole on its side wall. The first agitator is used to thoroughly stir the mixed solution after counter-mixing extraction. The extraction tank inlet is used to input the mixed solution after counter-mixing extraction into the extraction tank. The extraction tank discharge valve is used to discharge the high-COD wastewater from polyester resin for powder coatings after secondary extraction. The extraction tank drain hole is used to discharge the primary and secondary extraction solutions. There are multiple extraction tank drain holes, and the position of each drain hole should correspond to a different liquid level in the extraction tank. The electrocoagulation tank is equipped with... The electrocoagulation unit and the second agitator are respectively equipped with an electrocoagulation tank inlet and an electrocoagulation tank discharge valve on their bottom sides, and an electrocoagulation tank drain hole on their side wall. The electrocoagulation unit is used to realize electrochemical flocculation treatment, and the second agitator is used to realize the stirring function during the electrochemical flocculation treatment process. The electrocoagulation tank inlet is used to input high COD wastewater of polyester resin for powder coating after secondary extraction into the electrocoagulation tank. The electrocoagulation tank discharge valve is used to release viscous flocs, and the electrocoagulation tank drain hole is used to release the supernatant obtained after the electrochemical flocculation treatment. There are multiple electrocoagulation tank drain holes, and the position of each electrocoagulation tank drain hole should correspond to different liquid levels in the electrocoagulation tank.

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