Method for deep treatment of wastewater from electrolytic copper foil production

Abstract

The present application provides a method for deep treatment of electrolytic copper foil production wastewater, which relates to the technical field of industrial wastewater treatment. The method of the present application includes the steps of sequentially subjecting the wastewater to be treated to electrochemical oxidation treatment, coagulation and sedimentation treatment, and inflection point chlorination treatment; the electrochemical oxidation treatment is specifically as follows: introducing the wastewater into a reactor, and adjusting the pH value of the wastewater in this process section to a first target value, and achieving electrochemical oxidation treatment based on controlling the power supply of the reactor electrodes; the coagulation and sedimentation treatment is specifically as follows: introducing the effluent of the electrochemical oxidation reactor into a coagulation reaction tank, and adjusting the pH value of the wastewater in this process section to a second target value, then adding a coagulant and stirring at the same time to cause a flocculation reaction in the reaction tank, and the wastewater after the flocculation reaction enters a sedimentation tank for sedimentation separation. The technical solution of the present application adopts a specific physical and chemical treatment method, which can achieve effective deep treatment of copper foil wastewater that does not have the conditions for coordinated treatment.

Description

Technical Field

[0001] The present application relates to the technical field of industrial wastewater treatment, and in particular to a method for deep treatment of wastewater from electrolytic copper foil production. Background Art

[0002] Electrolytic copper foil is a high-purity copper foil produced through an electrolytic process, typically ranging in thickness from a few microns to tens of microns. Due to its excellent electrical, thermal, and mechanical properties, it is widely used in electronics, new energy, and other fields. With the development of related industries such as electronics, new energy, and 5G technology, the demand for electrolytic copper foil continues to grow, leading to a surge in related companies and production capacity.

[0003] The production of electrolytic copper foil generates wastewater containing a complex composition, including heavy metal ions (such as copper, zinc, nickel, cobalt, and chromium, particularly in complexed states that are more challenging to treat), organic additives, and various inorganic salts. This wastewater exhibits poor biodegradability and a severe imbalance in nutrient composition, making organic matter difficult to degrade. In particular, wastewater generated during surface treatment contains complexes formed between copper and potassium pyrophosphate, further complicating treatment. Furthermore, the heavy metal ions and certain organic compounds in the wastewater are toxic and harmful to the environment and organisms.

[0004] In practice, upstream wastewater dischargers must treat copper foil wastewater from their workshops to meet environmental impact assessment standards before discharging it into the municipal pipeline network. The wastewater then flows to downstream municipal wastewater treatment plants or industrial park wastewater treatment plants for further treatment before ultimately being discharged into natural water bodies. Discharging companies must meet the "Electronic Industry Water Pollutant Discharge Standard" (GB39731-2020) and the "Water Quality Standard for Wastewater Discharge into Urban Sewers" (GB / T31962-2015), while the effluent from downstream wastewater treatment plants must meet the surface water Class IV standard.

[0005] Among the current relevant technologies, the sewage-discharging enterprises usually use "multi-stage RO + coagulation and sedimentation + filtration + ion resin exchange" to treat copper foil wastewater to ensure that the effluent quality meets the standards; and municipal sewage treatment plants generally treat this type of "wastewater" discharged from the enterprise end in coordination with domestic sewage, using a combination process based on biological treatment such as "hydrolysis acidification + AAO-magnetic coagulation / AAO-MBR+advanced oxidation". This process route is mature and economical.

[0006] However, in the process of realizing the present invention, the inventors found that in the early stages of construction of some industrial parks, due to the lack of large-scale municipal sewage treatment plants in the surrounding areas or the small amount of domestic sewage in the initial stage of the sewage treatment plants, there are no conditions for coordinated treatment, resulting in the inability of existing sewage treatment processes to cope with this type of wastewater treatment, such as low efficiency and uneconomical problems. In view of this situation where there are no conditions for coordinated treatment, how to effectively treat this type of copper foil wastewater has become a technical problem that needs to be solved urgently. Summary of the Invention

[0007] In order to overcome the problems existing in the relevant technologies to at least a certain extent, this application proposes a method for deep treatment of electrolytic copper foil production wastewater, which adopts a specific physical and chemical treatment method to effectively treat copper foil wastewater that does not meet the conditions for coordinated treatment.

[0008] The present application provides a method for deep treatment of electrolytic copper foil production wastewater, which comprises the steps of sequentially subjecting the wastewater to be treated to electrochemical oxidation treatment, coagulation and sedimentation treatment, and breakpoint chlorination treatment;

[0009] The electrochemical oxidation treatment is carried out in an electrochemical oxidation reactor, specifically by introducing wastewater into the electrochemical oxidation reactor, adjusting the pH value of the wastewater in the electrochemical oxidation reactor to a first target value, and performing electrochemical oxidation treatment based on controlling the power supply of the reactor electrodes;

[0010] The coagulation and sedimentation treatment is carried out in a coagulation reaction tank and a sedimentation tank, specifically: the effluent from the electrochemical oxidation reactor is introduced into the coagulation reaction tank, and the pH value of the wastewater in the coagulation reaction tank is adjusted to a second target value, and then a coagulant is added and stirred at the same time to cause a flocculation reaction in the reaction tank, and the wastewater after the flocculation reaction enters the sedimentation tank for sedimentation separation.

[0011] In one possible implementation, the breakpoint chlorination treatment is carried out in a breakpoint chlorination reactor, specifically by introducing the supernatant formed by precipitation separation into the breakpoint chlorination reactor, and controlling the amount of chlorine introduced into the reactor to carry out the breakpoint chlorination treatment.

[0012] In one possible implementation, during the breakpoint chlorination treatment, the amount of chlorine added is 5-30 mg / L, the reaction time is 30-60 minutes, and the pH value is controlled at 6-8; the control index of the residual chlorine amount is 0.2-0.5 mg / L, and the control index of the mass ratio of chlorine to ammonia nitrogen is 7.6:1.

[0013] In one possible implementation, during the electrochemical oxidation treatment process, the inlet and outlet water COD, ammonia nitrogen and metal cation form distribution data are obtained in real time through online monitoring instruments, and the power supply of the reactor electrodes is controlled by a staged differentiated control method.

[0014] In one possible implementation, the electrochemical oxidation treatment process is divided into three stages: a rapid oxidation stage, a steady-state reaction stage, and an advanced treatment stage according to the kinetic characteristics of pollutant degradation. The power supply of the reactor electrodes is controlled by a staged and differentiated control method, specifically including:

[0015] When the COD is detected to be greater than a first predetermined value, a rapid oxidation period is entered, and a pulsed high current density treatment is started and coupled with intermittent aeration;

[0016] When the ammonia nitrogen degradation rate drops to a predetermined percentage of the initial rate, the system switches to a steady-state reaction period and dynamically adjusts the current density.

[0017] When the proportion of complexed metal is less than the second predetermined value, the process enters the deep treatment phase and switches to low current density operation.

[0018] In one possible implementation, the first predetermined value is 100 mg / L, the pulsed high current density is 30-50 mA / cm², the duty cycle is 30-50%, and the pulse frequency is 0.5-2 Hz; the predetermined percentage is 40%~60%; the second predetermined value is 15%, and the low current density is 10-20 mA / cm².

[0019] In a possible implementation, after entering the advanced treatment period, persulfate is further added to induce a free radical reaction.

[0020] In a possible implementation, the first target value is 3-8; and the reactor electrode is an iron-carbon electrode.

[0021] In one possible implementation, during the coagulation and sedimentation treatment process, the coagulant dosage is 10-50 mg / L, the stirring speed is 100-200 rpm, the stirring time is 10-20 minutes, and the sedimentation time is 1-2 hours; the second target value is 11.

[0022] In a possible implementation, the coagulant includes polyaluminum chloride and polyacrylamide; and the sedimentation tank is configured as an inclined plate sedimentation tank.

[0023] The method for deep treatment of electrolytic copper foil production wastewater provided in this application can effectively remove complex pollutant components in the wastewater, including heavy metal ions, organic additives and various inorganic salts, by sequentially performing electrochemical oxidation treatment, coagulation and sedimentation treatment, and inflection point chlorination treatment. It is suitable for treating wastewater containing complex metals. The technical solution of this application integrates multiple physical and chemical treatment processes to ensure that the effluent quality meets environmental water discharge standards even in the absence of domestic sewage dilution. It is particularly suitable for application scenarios in industrial parks or sewage treatment plants that do not have the conditions for coordinated treatment with municipal sewage treatment plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram illustrating a process for a method for deep treatment of electrolytic copper foil production wastewater provided in one embodiment of the present application;

[0025] Figure 2A schematic diagram illustrating the mechanism of the wastewater treatment process used in the prior art;

[0026] Figure 3 This is a schematic diagram illustrating the mechanism of the deep treatment process of copper foil production wastewater in the technical solution of this application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions of this application will be described in detail below.

[0028] As described in the background, electrolytic copper foil is a high-purity copper foil produced through an electrolytic process, typically ranging in thickness from a few microns to tens of microns. Due to its excellent electrical, thermal, and mechanical properties, it is widely used in electronics, new energy, and other fields. With the development of related industries such as electronics, new energy, and 5G technology, the demand for electrolytic copper foil continues to grow, and the construction of related companies and production capacity has also increased accordingly.

[0029] The production of electrolytic copper foil generates wastewater containing a complex composition, including heavy metal ions (such as copper, zinc, nickel, cobalt, and chromium, particularly in complexed states that are more challenging to treat), organic additives, and various inorganic salts, as shown in Table 1. This wastewater exhibits poor biodegradability and a severe imbalance in nutrient composition, making organic matter difficult to degrade. In particular, wastewater generated during surface treatment contains complexes formed between copper and potassium pyrophosphate, further complicating treatment. Furthermore, the heavy metal ions and certain organic compounds in the wastewater are toxic and harmful to the environment and organisms.

[0030] Table 1 Water quality of copper foil production wastewater from a certain enterprise

[0031]

[0032] Unit: mg / L, except pH

[0033] In practice, upstream pollutant-discharging enterprises must treat copper foil wastewater discharged from their workshops to meet environmental impact assessment standards before discharging it into the municipal pipeline network. The wastewater then enters a downstream municipal sewage treatment plant or industrial park sewage treatment plant for further treatment before ultimately being discharged into natural water bodies. The effluent standards at the pollutant-discharging enterprise end must comply with the "Electronic Industry Water Pollutant Discharge Standard" (GB39731-2020) and the "Water Quality Standard for Sewage Discharge into Urban Sewers" (GB / T31962-2015), while the effluent from the downstream sewage treatment plant must meet the surface water level Class IV standard. See Table 2 for details. As shown in Table 2, the effluent from the enterprise end actually meets the relevant regulatory standards, but is still far from the effluent standards of the sewage treatment plant.

[0034] Table 2 Water quality of effluent from the enterprise and downstream municipal sewage treatment plants

[0035]

[0036] Unit: mg / L, except pH

[0037] In the current related technologies, the sewage-discharging enterprises usually use "multi-stage RO + coagulation sedimentation + filtration + ion resin exchange" to treat copper foil wastewater to ensure that the effluent quality meets the standards; and municipal sewage treatment plants generally treat this type of "wastewater" discharged from the enterprise end in conjunction with domestic sewage, using a combination process based on biological treatment such as "hydrolysis acidification + AAO - magnetic coagulation / AAO-MBR + advanced oxidation". This process route is mature and economical. However, in the process of realizing the present invention, the inventors found that in the early stages of construction of some industrial parks, due to the lack of large-scale municipal sewage treatment plants in the surrounding areas or the small amount of domestic sewage in the initial startup of the sewage treatment plants, the conditions for coordinated treatment are not met, resulting in the existing sewage treatment process being unable to cope well with this type of wastewater treatment, and having problems such as low efficiency and uneconomical.

[0038] To address this, the present application proposes a method for deep treatment of electrolytic copper foil production wastewater, which adopts a specific physical and chemical treatment method to achieve more effective treatment of copper foil wastewater that does not meet the conditions for coordinated treatment.

[0039] like Figure 1 As shown, in one embodiment, the method for deep treatment of electrolytic copper foil production wastewater proposed in this application comprises the steps of sequentially subjecting the wastewater to be treated to electrochemical oxidation treatment, coagulation sedimentation treatment, and inflection point chlorination treatment;

[0040] The electrochemical oxidation treatment is carried out in an electrochemical oxidation reactor, specifically: wastewater is introduced into the reactor, and the pH value of the wastewater in the process section is adjusted to a first target value, and the electrochemical oxidation treatment is achieved based on controlling the power supply of the reactor electrodes;

[0041] Specifically, the above process introduces copper foil wastewater into an electrochemical oxidation reactor. By applying power to the electrodes, strong oxidants (such as hydroxyl radicals) generated at the anode oxidize and decompose organic matter in the wastewater (removing COD). These oxidants react particularly with long-chain and cyclic macromolecules, breaking down the organic matter and reducing wastewater toxicity. Furthermore, the strong oxidants generated at the anode chemically alter the complex structure of metal ions, facilitating subsequent metal ion removal. Through redox reactions at the cathode and anode, ammonia nitrogen in the wastewater is oxidized to nitrogen gas, achieving ammonia nitrogen removal. This also alters the metal ion form, which, combined with subsequent coagulation and sedimentation, ultimately achieves the removal of heavy metal ions. For example, copper ions react with iron-carbon electrode materials, displacing the copper and trapping it on the iron-carbon microelectrolysis filler, where it is separated from the wastewater and purified. Hexavalent chromium, under acidic conditions, reacts with the iron-carbon electrode materials and is reduced to trivalent chromium.

[0042] As a specific embodiment, an iron-carbon electrode is used in the electrochemical oxidation reactor, the current density is controlled at 10-50 mA / cm², the electrolysis time is 30-60 minutes, and the first target value is 3-8, that is, the pH value is controlled at 3-8;

[0043] In the technical scenario of this application, the use of iron-carbon electrodes can achieve the iron-carbon micro-electrolysis effect compared to the use of titanium-based coatings, graphite electrodes, stainless steel electrodes, platinum electrodes, etc. This effect is based on the primary cell reaction in electrochemistry. Under certain pH conditions, when iron and carbon are immersed in an electrolyte solution, due to the 1.2V electrode potential difference between Fe and C, countless micro-battery systems will be formed, forming an electric field in its action space. The new ecological divalent iron ions produced by the anode reaction have a strong reducing ability, which can reduce certain organic matter and open the double bonds of certain unsaturated groups (such as carboxyl-COOH, azo-N=N-), so that some difficult-to-degrade cyclic and long-chain organic matter can be decomposed into easily biodegradable small-molecule organic matter to improve biodegradability, which is more conducive to ensuring the efficiency of organic matter degradation.

[0044] In this embodiment, coagulation and sedimentation treatment is carried out in a coagulation reaction tank and a sedimentation tank, which is specifically: the effluent from the electrochemical oxidation reactor is introduced into the coagulation reaction tank, and the pH value of the wastewater in this process section is adjusted to a second target value, and then a coagulant is added and stirred at the same time to cause a flocculation reaction in the reaction tank. The wastewater after the flocculation reaction enters the sedimentation tank for sedimentation separation.

[0045] Specifically, the process involves introducing electrochemically oxidized wastewater into a coagulation tank. Alkali is added to adjust the pH to the target value based on the optimal precipitation of each metal ion. An appropriate amount of coagulant is then added, and stirring is performed to cause a flocculation reaction between the coagulant and the suspended matter and colloidal substances in the wastewater. The flocculated wastewater then enters a sedimentation tank for sedimentation separation to separate the flocs, while the supernatant enters the next treatment stage for the final removal of heavy metal ions.

[0046] As a specific implementation method, the above-mentioned second target value is 11. For example, by adding alkali (such as sodium hydroxide), the pH value of the wastewater in this process section can be gradually adjusted from acidic 3 to alkaline 11. The coagulant dosage is 10-50 mg / L. For example, the actual coagulant here can be polyaluminum chloride, polyacrylamide, etc., the stirring speed is 100-200 rpm, and the stirring time is 10-20 minutes; the sedimentation time is 1-2 hours to ensure that the flocs are fully settled.

[0047] As a preferred embodiment, the sedimentation tank in the coagulation and sedimentation treatment step of the present invention adopts the design of an inclined plate sedimentation tank. Compared with traditional vertical flow sedimentation tanks and radial flow sedimentation tanks, inclined plate sedimentation tanks have shown significant advantages in many aspects, and are particularly suitable for the application scenarios mentioned in the background technology in the initial construction of industrial parks that do not have the conditions for coordinated treatment with municipal sewage treatment plants. Specifically, the inclined plate sedimentation tank has a higher treatment capacity than the vertical flow sedimentation tank. By increasing the sedimentation area and improving the hydraulic conditions, the inclined plate sedimentation tank can more effectively capture and separate suspended particulate matter, thereby improving the wastewater treatment efficiency. This ensures good effluent water quality even when the industrial wastewater contains a high concentration of suspended solids and colloidal substances. Secondly, compared with the radial flow sedimentation tank, the inclined plate sedimentation tank occupies a smaller area. The effective use of space is one of the key factors that must be considered in engineering design. The smaller footprint not only reduces civil engineering costs, but also reduces the impact on the surrounding environment, which helps to achieve a more compact and efficient layout of sewage treatment facilities.

[0048] In the embodiment, the breakpoint chlorination treatment is carried out in a breakpoint chlorination reactor, specifically: the supernatant formed by precipitation separation in the previous process section is introduced into the breakpoint chlorination reactor, and the amount of chlorine introduced into the reactor is controlled to achieve the breakpoint chlorination treatment.

[0049] Specifically, in this process, the supernatant after coagulation and sedimentation separation is introduced into the breakpoint chlorination reactor, and an appropriate amount of chlorine gas or sodium hypochlorite solution is added. By controlling the amount of chlorine added, the breakpoint chlorination effect is achieved, and the residual organic matter and ammonia nitrogen are further oxidized and decomposed (organic matter is oxidized to CO2 by chlorine, and ammonia nitrogen is oxidized to nitrogen N2), thereby removing pollutants and ensuring that the final effluent is stable and meets the environmental water acceptance standards.

[0050] As a specific implementation method, during the breakpoint chlorination treatment process, the amount of chlorine added is controlled based on the real-time COD, ammonia nitrogen, pH and residual chlorine monitoring values of the wastewater in this process section to ensure that the reaction is sufficient and the residual chlorine does not exceed the standard. Specifically, during the implementation process, online detection instruments such as COD, ammonia nitrogen, residual chlorine, and pH value can be set in this process section to detect the COD, ammonia nitrogen, residual chlorine concentration, etc. in the wastewater in real time. The amount of sodium hypochlorite added is adjusted through a metering pump based on the instrument feedback data to ensure that the reaction is sufficient and no excessive chlorine residual is generated;

[0051] Specifically, in one implementation scenario, during breakpoint chlorination, the chlorine dosage is 5-30 mg / L, the reaction time is 30-60 minutes, the residual chlorine level is controlled at 0.2-0.5 mg / L, the chlorine to ammonia nitrogen mass ratio is controlled at 7.6:1, and the pH is controlled at 6-8. Based on actual operational experience, the reference value is to add 80-100 mg of sodium hypochlorite (with an available chlorine content of 10%) to remove 1 mg of ammonia nitrogen.

[0052] The method for deep treatment of electrolytic copper foil production wastewater provided in the embodiments of the present application can effectively remove complex pollutant components in the wastewater, including heavy metal ions, organic additives, and various inorganic salts, by sequentially performing electrochemical oxidation treatment, coagulation and sedimentation treatment, and inflection point chlorination treatment. By integrating multiple physical and chemical treatment processes, the present application can ensure that the effluent quality meets environmental water discharge standards even in the absence of coordinated treatment of domestic sewage. This is particularly suitable for industrial parks that do not have the conditions for coordinated treatment with municipal sewage treatment plants or for application scenarios in the initial stages of industrial park startup.

[0053] Specifically, for the application scenario of copper foil wastewater (there is no large-scale municipal sewage treatment plant around the enterprise or the sewage treatment plant has a small amount of domestic sewage in the initial stage and does not have the conditions for coordinated treatment), if the combined process commonly used in the existing industry is adopted, such as "pre-Fenton + coagulation sedimentation + hydrolysis acidification + AAO + MBR + post-Fenton + coagulation sedimentation", its process mechanism is combined with Figure 2 As shown, the pre-Fenton process primarily breaks down complexed metal ions, oxidizing and ring-breaking difficult-to-degrade COD to convert it into small molecules. Coagulation and sedimentation remove heavy metal ions, and hydrolysis and acidification improve the biodegradability of wastewater, creating favorable conditions for subsequent biological treatment. AAO+MBR is the core degradation unit, achieving high removal of COD, ammonia nitrogen, total nitrogen, and SS in the influent. Post-Fenton ensures that the effluent COD remains stable and meets standards, and coagulation and sedimentation are a backup measure to ensure that metal ions meet standards. This combined process is primarily biological, supplemented by physical and chemical treatment. Its disadvantages are that the process flow is long, and both investment and operating costs are high.

[0054] In contrast, the combined process used in the technical solution of this application does not require a biological treatment process, but only a physical and chemical treatment process, which is extremely simple, with low investment and operating costs and good economic efficiency. Figure 2 and 3 As shown in the figure, although both electrochemical oxidation and Fenton belong to the category of advanced oxidation processes, electrochemical oxidation can not only remove COD and heavy metals that Fenton can remove, but also remove ammonia nitrogen and total nitrogen (while Fenton has no removal effect). This method kills two birds with one stone and eliminates the need for a biological treatment system (i.e. AAO+MBR, mainly used to remove ammonia nitrogen, total nitrogen and BOD). Breakpoint chlorination replaces the traditional post-Fenton process, which can also further remove COD and ammonia nitrogen. However, compared with the post-Fenton process, the breakpoint chlorination process has greatly reduced investment and is simpler to operate and manage.

[0055] In some embodiments, in order to improve the efficiency of electrochemical oxidation treatment and comprehensively consider energy consumption, during the electrochemical oxidation treatment process, the COD, ammonia nitrogen and metal cation form distribution data of the inlet and outlet water are obtained in real time through an online monitoring device, and a staged differentiated control method is used to control the power supply of the reactor electrodes.

[0056] This approach allows the system to dynamically adjust operating parameters such as current density based on specific changes in water quality, ensuring optimal treatment results and minimal energy consumption at each treatment stage. For example, when pollutant concentrations are high, the current density is increased to accelerate degradation; when the water quality approaches the effluent standard, the current density is appropriately reduced to conserve energy. This flexible and precise control strategy not only improves treatment efficiency but also ensures the cost-effectiveness and environmental friendliness of the treatment process. It can also effectively address the challenges posed by fluctuating water quality, contributing to enhanced system stability and adaptability.

[0057] Specifically, in one implementation scenario, this application divides the electrochemical oxidation treatment process into three stages: rapid oxidation stage, steady-state reaction stage, and deep treatment stage according to the kinetic characteristics of pollutant degradation, targeting the characteristics of the wastewater in this scenario. Correspondingly, a staged and differentiated control method is used to control the power supply of the reactor electrodes, specifically including:

[0058] When the COD is detected to be greater than the first predetermined value, the rapid oxidation period begins, and pulsed high current density treatment is started and coupled with intermittent aeration to destroy the complex structure through the turbulent effect. For example, here the first predetermined value is 100 mg / L, the pulsed high current density is 30-50 mA / cm², the duty cycle is 30-50%, and the pulse frequency is 0.5-2 Hz.

[0059] During the overall process, the ammonia nitrogen degradation rate will also be determined through instrument monitoring data and evaluated accordingly. When the ammonia nitrogen degradation rate drops to a predetermined percentage of the initial rate, it will switch to the steady-state reaction period, dynamically adjust the current density, and stabilize the reaction rate to avoid ineffective energy consumption under high current density, while preventing electrode passivation to optimize the reaction efficiency. The predetermined percentage here is generally 40%~60%. For example, when the ammonia nitrogen degradation rate drops to 50% of the initial rate, it will switch to steady-state reaction period control and use a fuzzy PID algorithm to dynamically adjust the current density to maintain the ammonia nitrogen degradation rate at 50% of the initial rate. The fuzzy PID algorithm here can be implemented based on a pre-constructed transfer function of ammonia nitrogen degradation rate and current density.

[0060] As the reaction proceeds, the proportion of complexed metals will also change. When the proportion of complexed metals is less than a second predetermined value, the process enters a deep treatment phase and switches to low current density operation. For example, the second predetermined value here is 15%, and the low current density is 10-20 mA / cm².

[0061] Furthermore, as a preferred embodiment, after entering the deep treatment period, persulfate can also be added to induce a free radical reaction. For example, with 0.1 mmol / L as the target, sodium persulfate is added in a gradient (such as increasing by 0.02 mmol / L every 5 minutes). By adding an appropriate amount of persulfate, under low current density conditions, the metal ions generated at the anode will catalyze the decomposition of persulfate to produce sulfate radicals, thereby further improving the oxidation efficiency. This is particularly suitable for complex wastewater systems where complexed heavy metals and difficult-to-degrade organic matter coexist.

[0062] In addition, as another embodiment, during the electrochemical oxidation treatment process, photocatalytic materials can be added to the electrochemical oxidation reactor, and ultraviolet light or visible light can be used to stimulate the photocatalytic reaction to achieve synergistic effect with electrochemical oxidation. This combined application can not only effectively degrade organic pollutants in wastewater through electrochemical oxidation, but also further improve the treatment effect and efficiency with the help of the synergistic effect of photocatalysis.

[0063] Specifically, the photocatalytic materials used may include but are not limited to titanium dioxide TiO2. TiO2 is a widely studied and applied photocatalyst that can produce active oxygen species with strong oxidizing properties when irradiated by ultraviolet light or visible light of a specific wavelength. These active oxygen species can efficiently decompose difficult-to-degrade organic matter in water, thereby achieving a more thorough purification process. In this synergistic treatment mode, the electrochemical oxidation process provides the initial pollutant destruction effect, while photocatalysis accelerates this process by generating highly active free radicals. The two complement each other and greatly improve the overall treatment efficiency.

[0064] The method provided in this application for deep treatment of electrolytic copper foil production wastewater can effectively remove complex pollutant components in the wastewater, including heavy metal ions (such as copper, zinc, nickel, cobalt, chromium, etc.), organic additives and various inorganic salts, by sequentially performing electrochemical oxidation treatment, coagulation sedimentation treatment and inflection point chlorination treatment. It is particularly suitable for treating wastewater containing complex metals.

[0065] The technical solution of this application uses electrochemical oxidation as the primary step. By adjusting the power supply to the reactor electrodes, the distribution of COD, ammonia nitrogen, and metal cation forms in the influent and effluent water can be monitored in real time. The power supply to the electrodes is then controlled in stages based on the kinetics of pollutant degradation. This method not only efficiently oxidizes and decomposes difficult-to-degrade organic matter, but also converts complexed metals into easily separable forms, significantly improving overall treatment efficiency.

[0066] To specifically address the challenges of complex metal treatment, the technical solution of this application also addresses the characteristics of wastewater generated during the electrolytic copper foil production process, which contains a large amount of complex metals. By adjusting the current density and aeration method at different stages, the treatment strategy for complex metals is optimized. In particular, after entering the advanced treatment stage, the addition of persulfate to trigger free radical reactions further enhances the removal of residual complex metals and other trace pollutants.

[0067] The coagulation and sedimentation treatment step of this application uses polyaluminum chloride and polyacrylamide as coagulants, and stirring and precipitation are carried out at a pH of 11. This not only ensures a good flocculation effect, but also reduces the amount of coagulant used, lowering treatment costs. In addition, the breakpoint chlorination treatment step precisely controls the residual chlorine content and the mass ratio of chlorine to ammonia nitrogen, ensuring both the disinfection effect and the avoidance of secondary pollution caused by excessive chlorination, thus ensuring the economic and environmental friendliness of the technical solution of this application.

[0068] In summary, this application provides an efficient, economical and environmentally friendly method for deep treatment of electrolytic copper foil production wastewater, which solves the problems of high treatment difficulty, high cost and environmental risks existing in current technologies, and has important practical application significance.

[0069] The above description is merely a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by anyone familiar with the technology within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

[0070] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0071] It should be noted that, in the description of this application, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0072] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0073] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for deep treatment of electrolytic copper foil production wastewater, characterized in that: The method comprises the steps of sequentially subjecting the wastewater to be treated to electrochemical oxidation treatment, coagulation and sedimentation treatment, and breakpoint chlorination treatment; The electrochemical oxidation treatment is carried out in an electrochemical oxidation reactor, specifically by introducing wastewater into the electrochemical oxidation reactor, adjusting the pH value of the wastewater in the electrochemical oxidation reactor to a first target value, and performing electrochemical oxidation treatment based on controlling the power supply of the reactor electrodes; The coagulation and sedimentation treatment is carried out in a coagulation reaction tank and a sedimentation tank, specifically: the effluent from the electrochemical oxidation reactor is introduced into the coagulation reaction tank, and the pH value of the wastewater in the coagulation reaction tank is adjusted to a second target value, and then a coagulant is added while stirring to cause a flocculation reaction in the reaction tank, and the wastewater after the flocculation reaction enters the sedimentation tank for sedimentation separation; In the electrochemical oxidation process, the inlet and outlet COD, ammonia nitrogen and metal cation form distribution data are obtained in real time through online monitoring instruments, and the power supply of the reactor electrodes is controlled by a staged differentiated control method; the electrochemical oxidation process is divided into three stages: rapid oxidation period, steady-state reaction period and deep treatment period according to the kinetic characteristics of pollutant degradation. The staged differentiated control method is used to control the power supply of the reactor electrodes, specifically including: When it is detected that the COD is greater than the first predetermined value, the rapid oxidation period is entered, and pulsed high current density treatment is started and coupled with intermittent aeration. The pulsed high current density is 30-50 mA / cm², the duty cycle is 30-50%, and the pulse frequency is 0.5-2 Hz; when the ammonia nitrogen degradation rate drops to a predetermined percentage of the initial rate, it switches to the steady-state reaction period and dynamically adjusts the current density; when the proportion of complexed metals is less than the second predetermined value, it enters the deep treatment period and switches to low current density operation. The low current density is 10-20 mA / cm².

2. The method according to claim 1, wherein The inflection point chlorination treatment is carried out in a inflection point chlorination reactor, specifically: the supernatant formed by precipitation separation is introduced into the inflection point chlorination reactor, and the amount of chlorine introduced into the reactor is controlled to carry out the inflection point chlorination treatment.

3. The method according to claim 2, wherein: During the breakpoint chlorination treatment, the chlorine addition amount is 5-30 mg / L, the reaction time is 30-60 minutes, the pH value is controlled at 6-8; the control index of the residual chlorine amount is 0.2-0.5 mg / L, and the control index of the mass ratio of chlorine to ammonia nitrogen is 7.6:

1.

4. The method according to claim 1, wherein The first predetermined value is 100 mg / L; the predetermined percentage is 40% to 60%; and the second predetermined value is 15%.

5. The method according to claim 4, wherein After entering the deep treatment period, persulfate is also added to induce free radical reaction.

6. The method according to claim 2, wherein: The first target value is 3-8; the reactor electrode is an iron-carbon electrode.

7. The method according to claim 6, wherein: During the coagulation and sedimentation treatment process, the coagulant dosage is 10-50 mg / L, the stirring speed is 100-200 rpm, the stirring time is 10-20 minutes, and the sedimentation time is 1-2 hours; the second target value is 11.

8. The method according to claim 7, wherein: The coagulant includes polyaluminium chloride and polyacrylamide; the configuration of the sedimentation tank is an inclined plate sedimentation tank.

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