Advanced treatment method for electrolytic copper foil production wastewater

Abstract

The invention provides a method for advanced treatment of electrolytic copper foil production wastewater, and relates to the technical field of industrial sewage treatment.The method comprises the steps that to-be-treated wastewater is sequentially subjected to electrochemical oxidation treatment, coagulating sedimentation treatment and breakpoint chlorination treatment; the electrochemical oxidation treatment specifically comprises the following steps: introducing the wastewater into a reactor, adjusting the pH value of the wastewater in the process section to a first target value, and realizing the electrochemical oxidation treatment based on the power-up condition of a reactor electrode; and the coagulating sedimentation treatment specifically comprises the following steps: introducing the effluent of the electrochemical oxidation reactor into a coagulation reaction tank, adjusting the pH value of the wastewater in the process section to a second target value, adding a coagulant, stirring to generate a flocculation reaction in the reaction tank, and introducing the wastewater subjected to the flocculation reaction into a sedimentation tank for precipitation separation. According to the technical scheme, a specific physical and chemical treatment mode is adopted, and effective deep treatment can be achieved on the copper foil wastewater without cooperative treatment conditions.

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 by an electrolytic process, with a thickness usually ranging from a few microns to tens of microns. Due to its excellent electrical conductivity, thermal conductivity 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.

[0003] Wastewater is generated during the production of electrolytic copper foil. The wastewater contains complex components, including heavy metal ions (such as copper, zinc, nickel, cobalt, chromium, etc., especially in complexed states that are more difficult to treat), organic additives, and various inorganic salts. The biodegradability of these wastewaters is poor and the nutrient ratio is seriously unbalanced, making it difficult to degrade organic matter. In particular, the wastewater generated during the surface treatment process contains complexes formed by copper and potassium pyrophosphate, which increases the difficulty of treatment. At the same time, the heavy metal ions and certain organic matter in the wastewater are toxic and harmful to the environment and organisms.

[0004] In actual operation, the copper foil wastewater discharged from the workshop of the upstream sewage discharge enterprise needs to undergo certain treatment, and then be discharged into the municipal pipe network after meeting the environmental impact assessment standards, and then enter the downstream municipal sewage treatment plant or industrial park sewage treatment plant for further treatment, and finally discharged into natural water bodies. Among them, the sewage effluent standards of the sewage discharge enterprise 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), and the effluent of the downstream sewage treatment plant must meet the surface water level Class IV standard.

[0005] In the current relevant 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 coordination with domestic sewage, using a combination of biological treatment-based processes 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 lack of coordinated treatment conditions, 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 related art to at least a certain extent, the embodiment of the present application provides 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] In some embodiments of the present application, a method for deep treatment of electrolytic copper foil production wastewater is provided, the method comprising the steps of sequentially subjecting the wastewater to be treated to electrochemical oxidation treatment, coagulation sedimentation treatment and inflection point chlorination treatment; The electrochemical oxidation treatment is carried out in an electrochemical oxidation reactor, specifically: introducing wastewater into the reactor, adjusting the pH value of the wastewater in the process section to a first target value, and realizing 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 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, and the wastewater after the flocculation reaction enters the sedimentation tank for sedimentation separation.

[0009] In one possible implementation, the inflection point chlorination treatment is carried out in an 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 achieve the inflection point chlorination treatment.

[0010] In a 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.

[0011] In a 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.

[0012] In a possible implementation, the electrochemical oxidation treatment process is divided into three stages: rapid oxidation stage, steady-state reaction stage and deep treatment stage according to the kinetic characteristics of pollutant degradation; the power-on condition of the reactor electrodes is controlled by a staged differentiated control method, specifically including: When it is detected that the COD is 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; When the ammonia nitrogen degradation rate drops to a predetermined percentage of the initial rate, the reaction is switched to a steady-state reaction period, and the current density is dynamically adjusted; When the proportion of complexed metal is less than the second predetermined value, the process enters the deep treatment period and switches to low current density operation.

[0013] 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.

[0014] In a possible implementation, after entering the deep treatment period, persulfate is further added to induce a free radical reaction.

[0015] In a possible implementation, the first target value is 3-8; and the reactor electrode is an iron-carbon electrode.

[0016] In a 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.

[0017] In a possible implementation, the coagulant includes polyaluminium chloride and polyacrylamide; and the sedimentation tank is configured as an inclined plate sedimentation tank.

[0018] The method for deep treatment of electrolytic copper foil production wastewater provided in the embodiment 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 sedimentation treatment and inflection point chlorination treatment, and is suitable for treating wastewater containing complex metals. The technical solution of the present application integrates a variety of physical and chemical treatment processes to ensure that the effluent quality meets the environmental water discharge standards even in the absence of domestic sewage dilution, and 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.

[0019] Other advantages, objectives, and features of the present application will be described in part in the following description, and in part will be apparent to those skilled in the art based on the following examination and study, or may be taught from the practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the technical solution of the present application or the prior art, and constitute a part of the specification. Among them, the accompanying drawings expressing the embodiments of the present application are used together with the embodiments of the present application to explain the technical solution of the present application, but do not constitute a limitation on the technical solution of the present application.

[0021] Figure 1 A schematic diagram illustrating a process of a method for deep treatment of electrolytic copper foil production wastewater provided in one embodiment of the present application; Figure 2 It is a schematic diagram illustrating the mechanism of the wastewater treatment process used in the prior art; 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

[0022] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other implementation methods obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0023] As described in the background technology, electrolytic copper foil is a high-purity copper foil produced by an electrolytic process, and its thickness is usually between a few microns and tens of microns. Due to its excellent electrical conductivity, thermal conductivity 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 enterprises and production capacity has also increased accordingly.

[0024] Wastewater is generated during the production of electrolytic copper foil. These wastewaters contain complex components, including heavy metal ions (such as copper, zinc, nickel, cobalt, chromium, etc., especially in complexed states that are more difficult to treat), organic additives, and various inorganic salts, as shown in Table 1. These wastewaters have poor biodegradability and serious imbalance in nutrient ratios, and organic matter is difficult to degrade. In particular, the wastewater generated during the surface treatment process contains complexes formed by copper and potassium pyrophosphate, which increases the difficulty of treatment. At the same time, heavy metal ions and certain organic matter in the wastewater are toxic and harmful to the environment and organisms.

[0025] Table 1 Water quality of copper foil production wastewater from a certain enterprise Unit: mg / L, except pH In actual operation, the copper foil wastewater discharged from the workshop of the upstream sewage-discharging enterprise needs to undergo certain treatment, and then be discharged into the municipal pipe network after meeting the environmental impact assessment standards, and then enter the downstream municipal sewage treatment plant or industrial park sewage treatment plant for further treatment, and finally discharged into natural water bodies. Among them, the sewage effluent standards of the sewage-discharging enterprise 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 of 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 sewage effluent of the enterprise has actually met the relevant regulations and standards, but it is still far from the effluent standards of the sewage treatment plant.

[0026] Table 2 Water quality of effluent from the enterprise and downstream municipal sewage treatment plants Unit: mg / L, except pH 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 coordination with domestic sewage, using a combination of biological treatment-based processes 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 the 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 plant, there are no conditions for coordinated treatment, resulting in the inability of existing sewage treatment processes to cope with this type of wastewater treatment, and there are problems such as low efficiency and uneconomical.

[0027] In view of 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.

[0028] like Figure 1 As shown, in one embodiment, the method for deep treatment of electrolytic copper foil production wastewater proposed in the present application comprises the steps of sequentially subjecting the wastewater to be treated to electrochemical oxidation treatment, coagulation sedimentation treatment and inflection point chlorination treatment; Among them, the electrochemical oxidation treatment is carried out in an electrochemical oxidation reactor, specifically: introducing wastewater into the reactor, and adjusting the pH value of the wastewater in the process section to a first target value, and realizing the electrochemical oxidation treatment based on controlling the power supply of the reactor electrodes; Specifically, in the above process, copper foil wastewater is introduced into an electrochemical oxidation reactor, and the electrodes are electrified, and the strong oxidants (such as hydroxyl radicals) generated by the anode are used to oxidize and decompose the organic matter in the wastewater (remove COD), especially reacting with long-chain and cyclic macromolecular organic matter, breaking the organic matter chain and decomposing it, while also reducing the toxicity of the wastewater. At the same time, the strong oxidants generated by the anode can also change the metal ion complex structure through chemical action, which is conducive to the further removal of subsequent metal ions; using the redox reaction of the cathode and anode, ammonia nitrogen in the wastewater can be oxidized to nitrogen gas to achieve the purpose of removing ammonia nitrogen, and at the same time, the metal ion form can be changed, and then combined with subsequent coagulation and precipitation, the purpose of removing heavy metal ions is finally achieved. For example, copper ions, after reacting with electrode materials such as iron and carbon, copper is replaced and retained on the iron-carbon micro-electrolysis filler, separated from the wastewater, and purified. Hexavalent chromium is reduced to trivalent chromium under acidic conditions after reacting with electrode materials such as iron and carbon.

[0029] As a specific implementation, 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; In the technical scenario of this application, the iron-carbon electrode can realize the iron-carbon micro-electrolysis effect compared with the titanium-based coating, graphite electrode, stainless steel electrode, platinum electrode, etc. This effect is based on the primary cell reaction in electrochemistry. Under certain pH conditions, when iron and carbon are immersed in the electrolyte solution, due to the electrode potential difference of 1.2V 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 strong reducing ability, which can reduce some organic matter, and can also open the double bonds of some 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 biodegradable small-molecule organic matter and improve biodegradability, which is more conducive to ensuring the efficiency of organic matter degradation.

[0030] 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 the 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, and the wastewater after the flocculation reaction enters the sedimentation tank for sedimentation separation.

[0031] Specifically, in this process, the wastewater treated by electrochemical oxidation is introduced into the coagulation reaction tank, and the pH value is adjusted to the target value by adding alkali according to the optimal pH value for precipitation of each metal ion, and then an appropriate amount of coagulant is added, and the coagulant is stirred to cause flocculation reaction with the suspended matter and colloidal substances in the wastewater. The flocculated wastewater enters the sedimentation tank for sedimentation separation to separate the flocs, and the supernatant enters the next treatment link to achieve the final removal of heavy metal ions.

[0032] 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 the 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.

[0033] As a preferred specific embodiment, the sedimentation tank in the coagulation 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, the inclined plate sedimentation tank has shown significant advantages in many aspects, and is particularly suitable for the application scenarios mentioned in the background technology in the initial stage of industrial park construction that do not have the conditions for the coordinated treatment of municipal sewage treatment plants. Specifically, the inclined plate sedimentation tank has a higher processing 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 particles, thereby improving the wastewater treatment efficiency. This ensures good effluent water quality even when there are high concentrations of suspended solids and colloidal substances in industrial wastewater. 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 the civil construction cost, but also reduces the impact on the surrounding environment, which helps to achieve a more compact and efficient layout of sewage treatment facilities.

[0034] In the embodiment, the inflection point chlorination treatment is carried out in a inflection point chlorination reactor, specifically: the supernatant formed by precipitation separation in the previous process stage is introduced into the inflection point chlorination reactor, and the amount of chlorine introduced into the reactor is controlled to achieve the inflection point chlorination treatment.

[0035] 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. The amount of chlorine added is controlled to achieve the effect of breakpoint chlorination, 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.

[0036] As a specific implementation method, during the breakpoint chlorination treatment process, the amount of chlorine is controlled based on the real-time COD, ammonia nitrogen, pH and residual chlorine monitoring values ​​of the wastewater in the 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 the process section to detect the COD, ammonia nitrogen, and residual chlorine concentrations in the wastewater in real time. The amount of sodium hypochlorite added is adjusted through a metering pump according to the instrument feedback data to ensure that the reaction is sufficient and no excessive chlorine residue is generated; Specifically, in one implementation scenario, during the breakpoint chlorination treatment process, the chlorine addition amount is 5-30 mg / L, the reaction time is 30-60 minutes, the control index of the residual chlorine amount is 0.2-0.5 mg / L, the control index of the mass ratio of chlorine to ammonia nitrogen is 7.6:1, and the pH value is controlled at 6-8. According to actual operating experience, the reference value is to add 80-100 mg of sodium hypochlorite (effective chlorine content 10%) to remove 1 mg of ammonia nitrogen.

[0037] The method for deep treatment of electrolytic copper foil production wastewater provided in the embodiment 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 sedimentation treatment and inflection point chlorination treatment. In the present application, by integrating a variety of physical and chemical treatment processes, it can ensure that the effluent quality meets the environmental water discharge standards even in the absence of coordinated treatment of domestic sewage, which is particularly suitable for industrial parks that do not have the conditions for coordinated treatment of municipal sewage plants or application scenarios in the initial stage of industrial park startup.

[0038] 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 of startup, and the conditions for coordinated treatment are not met), 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 is mainly used to break complex metal ions, oxidize and break the ring of difficult-to-degrade COD to convert it into small molecules, coagulation and sedimentation remove heavy metal ions, and hydrolysis and acidification can improve the biodegradability of wastewater, creating favorable conditions for subsequent biological treatment. AAO+MBR is the core degradation unit, which has a high removal of COD, ammonia nitrogen, total nitrogen, and SS in the influent. Post-Fenton is to ensure that the effluent COD is stable and meets the standard, and coagulation and sedimentation are the bottom-line measures to ensure that metal ions meet the standard. This combined process is mainly based on biological treatment, supplemented by physical and chemical treatment. The disadvantage of the process is that the process flow is long, and the investment and operating costs are high; 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 has a very simple process, low investment and operating costs, and good economic efficiency. Figure 2 and3 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 simpler operation and management.

[0039] 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.

[0040] This method allows the system to dynamically adjust operating parameters such as current density according to specific changes in water quality to ensure that the best treatment effect and the lowest energy consumption can be achieved at different treatment stages. For example, when the pollutant concentration is high, the current density is increased to accelerate the degradation process; when it is close to the effluent standard, the current density is appropriately reduced to save energy consumption. This flexible and precise control strategy not only improves the treatment efficiency, but also ensures the economy and environmental friendliness of the treatment process. It can also effectively cope with the challenges brought by water quality fluctuations, which is conducive to enhancing the stability and adaptability of the system.

[0041] Specifically, in one implementation scenario, the present application divides the electrochemical oxidation treatment process into three stages: rapid oxidation period, steady-state reaction period and deep treatment period according to the kinetic characteristics of pollutant degradation, targeting the characteristics of wastewater in the scenario; correspondingly, a staged and differentiated control method is adopted to control the power-on of the reactor electrodes, specifically including: When it is detected that COD is greater than the first predetermined value, the rapid oxidation period begins, pulsed high current density treatment is started and intermittent aeration is coupled to destroy the complex structure through turbulence effect. For example, the first predetermined value here 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.

[0042] During the overall process, the ammonia nitrogen degradation rate is also determined through instrument monitoring data and evaluated accordingly. When the ammonia nitrogen degradation rate drops to a predetermined percentage of the initial rate, it switches to the steady-state reaction period, dynamically adjusts the current density, and stabilizes 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 switches to steady-state reaction period control, and uses 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.

[0043] As the reaction proceeds, the proportion of complexed metals will also change. When the proportion of complexed metals is less than the second predetermined value, the process enters the deep treatment period 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.

[0044] 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 a target of 0.1 mmol / L, 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.

[0045] In addition, as another implementation method, 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 effects 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.

[0046] 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 with 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.

[0047] The defects in the above solutions are the results obtained by the inventor after practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed by this application for the above problems below should be the contributions made by the inventor to this application during the application process. The method provided in the present 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.

[0048] In the technical solution of this application, electrochemical oxidation treatment is used as the primary step. By adjusting the power supply of the reactor electrodes, the distribution data of COD, ammonia nitrogen and metal cation forms in the inlet and outlet water can be monitored in real time, and the power supply of the electrodes can be controlled in stages according to the kinetic characteristics of pollutant degradation. This method can not only efficiently oxidize and decompose difficult-to-degrade organic matter, but also convert complexed metals into forms that are easy to separate, significantly improving the overall treatment efficiency.

[0049] In order to solve the problem of complex metal treatment in a targeted manner, the technical solution of this application also optimizes the treatment strategy for complex metals by adjusting the current density and aeration method at different stages in view of the fact that the wastewater generated during the production of electrolytic copper foil contains a large amount of complex metals. In particular, after entering the deep treatment period, the removal effect of residual complex metals and other trace pollutants is further enhanced by adding persulfate to induce free radical reactions.

[0050] In the coagulation and sedimentation treatment step of the present application, polyaluminium chloride and polyacrylamide are used as coagulants, and stirring and precipitation are performed under the condition of pH 11, which not only ensures a good flocculation effect, but also reduces the amount of coagulant used and reduces the treatment cost. In addition, the breakpoint chlorination treatment step accurately controls the residual chlorine amount and the mass ratio of chlorine to ammonia nitrogen, which not only ensures the disinfection effect but also avoids the secondary pollution problem caused by excessive chlorination, ensuring the economy and environmental friendliness of the technical solution of the present application.

[0051] In summary, the present 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 the current technology, and has important practical application significance.

[0052] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the technology within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0053] 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.

[0054] It should be noted that, in the description of this application, the terms "first", "second", etc. are only used for descriptive purposes and cannot 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.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0056] 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 sedimentation treatment and breakpoint chlorination treatment; The electrochemical oxidation treatment is carried out in an electrochemical oxidation reactor, specifically: introducing wastewater into the reactor, adjusting the pH value of the wastewater in the process section to a first target value, and realizing 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 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, and the wastewater after the flocculation reaction enters the sedimentation tank for sedimentation separation.

2. The method according to claim 1, wherein: The inflection point chlorination treatment is carried out in an 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 achieve the inflection point chlorination treatment.

3. The method according to claim 2, wherein: 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.

4. The method according to claim 2, wherein: 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.

5. The method according to claim 4, wherein: According to the kinetic characteristics of pollutant degradation, the electrochemical oxidation treatment process is divided into three stages: rapid oxidation period, steady-state reaction period and deep treatment period; the power-on condition of the reactor electrode is controlled by a staged and differentiated control method, specifically including: When it is detected that the COD is 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; When the ammonia nitrogen degradation rate drops to a predetermined percentage of the initial rate, the reaction is switched to a steady-state reaction period, and the current density is dynamically adjusted; When the proportion of complexed metal is less than the second predetermined value, the process enters the deep treatment period and switches to low current density operation.

6. The method according to claim 5, wherein: 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.

7. The method according to claim 6, wherein: After entering the deep treatment period, persulfate is also added to induce free radical reaction.

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

9. The method according to claim 8, 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.

10. The method according to claim 9, wherein: The coagulant includes polyaluminium chloride and polyacrylamide; the sedimentation tank is configured as an inclined plate sedimentation tank.

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