Coupling type wet oxidation treatment system for continuously recycling catalyst

Abstract

The invention belongs to the technical field of wastewater treatment, and discloses a coupled wet oxidation treatment system for continuously recycling a catalyst, which comprises a homogeneous regulating tank, a catalytic wet oxidation reaction device (comprising a high-pressure pump and a heat exchanger), a neutralization sedimentation tank, a filtering device, an online monitoring and regulating device and a resin purification device. The invention provides a systematic improvement aiming at engineering defects of a traditional copper salt homogeneous catalysis wet oxidation system. Sodium sulfide is used for removing most of copper in wet oxidation effluent, settled copper sulfide-containing slurry is creatively and directly recycled as a wet oxidation catalyst, and a closed-loop circulation system of the catalyst is constructed; and the residual trace copper in the supernate is deeply removed by a resin purification device filled with non-ion exchange chelate resin. According to the invention, high coupling of the catalyst recycling / purifying system and the wet oxygen system is realized, the operation cost and the secondary pollution risk of the homogeneous catalysis wet oxygen system are reduced, and the industrial application feasibility of the homogeneous catalysis wet oxygen system is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, in particular to a coupled wet oxidation treatment system with continuous recycling of catalysts. Background Art

[0002] Wet air oxidation (WAO) technology involves the oxidative degradation of dissolved or suspended organic matter and reduced inorganic matter in water using oxygen or air as an oxidant under high pressure (0.5-20 MPa) and high temperature (120-350°C) conditions. Catalytic wet oxidation (CWAO) incorporates a catalyst into WAO, effectively reducing the activation energy of the reaction, thereby significantly increasing the reaction rate and shortening the reaction time, simplifying operating conditions, and reducing engineering investment. Both heterogeneous and homogeneous catalysts are used in CWAO. Homogeneous CWAO has been studied since the 1970s and has achieved some application. However, given the challenges of catalyst loss, which were difficult to overcome at the time, including the economic losses and secondary pollution caused by catalyst loss, research has gradually shifted its focus to heterogeneous catalysis since the 1980s. The active components of heterogeneous catalysts are mainly precious metals such as Pt, Pd, Rh, Ru, and Ir, or non-precious metals such as Cu, Mn, Ce, Co, Fe, and Ni. Since the CWAO reaction process is a high-temperature and high-pressure state, and organic matter is often degraded into small-molecule carboxylic acid substances, the pH of the reaction solution decreases accordingly, which causes the solid catalyst to easily lose active components due to phase transition, acid dissolution, coordination, etc. In addition, another problem with heterogeneous CWAO is the carbon accumulation phenomenon on the catalyst surface, that is, certain polymers originally or generated by the reaction are adsorbed and deposited on the catalyst surface, preventing the active components from contacting the reactants, resulting in a decrease in catalytic efficiency. In order to reduce the carbon deposition phenomenon, heterogeneous CWAO requires that the suspended solids concentration in the influent be maintained at a low level (usually less than 20 mg / L), which limits the application of this technology in municipal sludge, chemical sludge, and some high-suspended solids organic wastewater fields.

[0003] Among homogeneous non-precious metal catalysts, soluble copper salts are generally found to possess strong catalytic activity, and copper nitrate generally outperforms copper sulfate and copper chloride in catalytic performance. The CWAO process often treats highly concentrated wastewater with COD concentrations exceeding 15,000 mg / L. To ensure effectiveness, the copper salt dosage typically reaches tens to hundreds of mg / L (measured in Cu). Because copper ions are toxic heavy metals, to avoid secondary pollution, national standards require that copper ions in CWAO effluent be reduced to below 0.5 mg / L. Existing patents such as CN 117509982 A and CN 109071288 B utilize resin adsorption devices directly installed at the back end of the CWAO process to recover and purify copper ions. Given the high copper ion concentration in CWAO effluent, this approach presents significant technical and economic challenges: while using a large-capacity adsorption device can extend the operating cycle, the resin equipment is large and investment costs are high. Reducing the device size leads to resin saturation, resulting in frequent desorption and regeneration. Both approaches inevitably increase wastewater treatment costs. Furthermore, most of the resins used are cation exchange resins based on electrostatic attraction. As the salinity of the system increases, their copper ion removal efficiency decreases significantly due to competition from coexisting cations, making them difficult to apply to high-salinity wastewater. Existing technologies for copper sulfide recycling face the problem of particle agglomeration and deactivation, while copper ion adsorption in high-salinity wastewater poses the risk of secondary contamination due to inappropriate resin selection. These two factors together limit the industrial application of catalytic wet oxidation processes.

[0004] In order to improve the defects of the existing technology, the present invention studies a coupled wet oxidation treatment system that can simultaneously achieve efficient recycling of catalyst copper salts and stably avoid secondary pollution. Summary of the Invention

[0005] To achieve the above-mentioned purpose, the present invention provides a coupled wet oxidation treatment system with continuous recycling of catalysts, which solves the above-mentioned technical problems.

[0006] The present invention provides a coupled wet oxidation treatment system for continuous recycling of catalysts, comprising a homogenization regulating tank, a catalytic wet oxidation reaction device (including a high-pressure pump and a heat exchanger), a neutralization sedimentation tank, a filtering device, an online monitoring and control device, and a resin purification device connected in sequence.

[0007] Furthermore, sodium sulfide and aluminum salt are added to the neutralization sedimentation tank to generate a slurry containing copper sulfide and aluminum hydroxide and recycled to the homogenization regulating tank; the resin purification device is filled with a non-ion exchange chelating resin, and the resin has a primary / secondary / tertiary amine or diaminomethylpyridine structure.

[0008] Furthermore, the operation process of the coupled wet oxidation treatment system with continuous recycling of the catalyst includes the following steps:

[0009] During the first run, catalyst is directly added to the high-concentration wastewater in the homogenization regulating tank for uniform mixing. In subsequent runs, the copper sulfide slurry settled from the neutralization sedimentation tank is recycled as catalyst and also mixed with the high-concentration wastewater in the homogenization regulating tank. After the pH of the mixed wastewater in the homogenization regulating tank is adjusted with acid / alkali, it is pumped by a high-pressure pump to a heat exchanger for preheating before entering the catalytic wet oxidation reactor for reaction. The wet oxygen effluent is cooled in the same heat exchanger and discharged to the neutralization sedimentation tank. After the wet oxygen effluent in the neutralization sedimentation tank cools, alkali is added to adjust the pH. Sodium sulfide and polyacrylamide (PAM) are then added. Gravity settling separates the copper sulfide slurry and supernatant. The copper sulfide slurry is then recycled to the homogenization regulating tank. The supernatant is filtered through a filtration device, and the resulting filtrate is monitored for copper concentration using an online monitoring and control device. If the filtrate meets the standard, it is discharged directly. Otherwise, a resin purification device is used for deep copper removal to ensure that the standard is met before discharge.

[0010] Furthermore, the catalyst added during the first run is a mixture of copper salt and aluminum salt, wherein the copper salt is a mixture of one or more of copper nitrate, copper sulfate, copper chloride, copper carbonate, copper acetate, copper oxide, copper hydroxide, basic copper carbonate, basic copper sulfate, and copper sulfide, and the aluminum salt is a mixture of one or more of aluminum chloride, aluminum sulfate, aluminum nitrate, alum, aluminum hydroxide, polyaluminum chloride, polyaluminum sulfate, and polyaluminum chlorsulfide, and the molar ratio of the aluminum salt to the copper salt is 1:0.2 to 1:2.

[0011] Furthermore, the main solid components of the copper sulfide slurry produced by gravity sedimentation in the neutralization sedimentation tank are copper sulfide and aluminum hydroxide.

[0012] Furthermore, acid / alkali is added to the mixed wastewater in the homogenization regulating tank to adjust the pH value to 3-5; the wastewater in the neutralization sedimentation tank is cooled to below 50° C., and alkali is added to adjust the pH value to 6-11, wherein the alkali is one or a mixture of ammonia water, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, and sodium bicarbonate.

[0013] Furthermore, the pressure in the catalytic wet oxidation reaction device is 0.5-20 MPa, the temperature is 120-350° C., and air or oxygen is introduced as an oxidant.

[0014] Furthermore, the resin filled in the resin purification device is a non-ion exchange chelating resin having a primary / secondary / tertiary amine structure or the following diaminomethylpyridine (Bis-Picolylamine) structure:

[0015]

[0016] Furthermore, the online monitoring and control device monitors the copper concentration C1 (mg / L) of the filtrate discharged from the filtration device and the copper concentration C2 (mg / L) of the water treated by the resin purification device. The conditions for controlling the deep purification treatment of the filtrate by the online monitoring and control device include:

[0017] When the copper concentration C1 of the filtrate discharged from the filtration device is lower than the control limit concentration C0 (mg / L), the online monitoring and control device controls the reversing valve to discharge the filtrate directly;

[0018] When the copper concentration C1 of the filtrate discharged from the filtration device is higher than the control limit concentration C0, the online monitoring and control device controls the reversing valve to discharge the filtrate into the resin purification device for emergency treatment; at this time, when the copper concentration C2 of the effluent treated by the resin purification device is lower than the control limit concentration C0, the treated effluent is directly discharged; when the copper concentration C2 of the effluent treated by the resin purification device is higher than the control limit concentration C0, the water intake is stopped and the resin purification device starts desorption regeneration. When the copper concentration of the effluent from the resin purification device exceeds the standard for three consecutive times, an automatic alarm is triggered and the backup resin tank is started.

[0019] The basic principle of the coupled wet oxidation treatment system for continuous recycling of catalysts provided by the present invention is as follows:

[0020] After the system has been running continuously (not for the first time), the catalyst used in the catalytic wet oxidation reaction process comes from the copper sulfide slurry settled in the neutralization sedimentation tank. The main components of this slurry are copper sulfide and aluminum hydroxide. By returning the slurry to the homogenization regulating tank and adding acid / base to adjust the pH to 3-5, the aluminum hydroxide component in the slurry is dissolved, and the remaining copper sulfide particles are smaller and can be mixed evenly with the high-concentration wastewater under mechanical stirring. The resulting mixed wastewater is transported to the catalytic wet oxidation reaction unit for reaction. The copper sulfide in the wastewater reacts with oxygen under high pressure and high temperature conditions to convert into dissolved copper ions:

[0021]

[0022] Copper sulfide can serve as a heterogeneous catalyst, while the copper ions generated by copper sulfide oxidation can serve as a homogeneous catalyst. Therefore, the wet oxidation reaction process in this system exhibits a dual catalytic mode, with heterogeneous catalysis gradually transitioning to homogeneous catalysis. After the wet oxidation reaction, the copper ions typically complex with the generated small-molecule organic acids, inorganic ammonia, and other substances. By adding alkali to the neutralization and sedimentation tank to adjust the pH to 6-11, the aluminum ions in the wet oxygen effluent are converted back into aluminum hydroxide precipitates. Subsequently, the addition of sodium sulfide and PAM converts most of the free or complexed copper ions into fine copper sulfide particles. Through the netting, sweeping, and co-precipitation of the aluminum hydroxide precipitate and PAM, the fine copper sulfide particles settle to form a copper sulfide-containing slurry, which is then returned to the homogenization regulating tank, enabling catalyst recycling. Compared to other catalytic wet oxidation reaction systems that primarily utilize soluble copper salts or solid catalysts loaded with CuO or copper-containing spinels, this patent pioneers the use of copper sulfide as a catalyst, achieving efficient catalyst recycling.

[0023] For catalytic wet oxidation effluent with complex water quality, adding sodium sulfide cannot guarantee stable copper removal to standard. Therefore, this system is equipped with an online monitoring and control device and a resin purification device. The online monitoring and control device monitors the copper concentration in the filtrate discharged from the filtration device. When the concentration exceeds the control limit, the reversing valve is immediately controlled to discharge the filtrate into the resin purification device for emergency treatment. The resin used for deep copper removal is a non-ion exchange chelating resin with a primary / secondary / tertiary amine structure or a bis-picolylamine structure. It has a high affinity for copper ions in both free ionic and complexed states. Compared with conventional cation exchange resins, the copper removal process of this resin is not inhibited by high salinity in the wastewater, and the copper removal effect is stable and reliable. This conclusion has been confirmed by research papers such as "Preparation, Characterization, Performance and Mechanism of a Novel Polyamine Chelating Resin for High-Efficiency and High-Selectivity Separation and Removal of Typical Heavy Metal Ions" (2014) and "Separation Characteristics of a Novel Pyridine-Based Chelating Resin for Copper and Nickel in Strong Acid and High-Salinity Solutions" (2017).

[0024] The coupled wet oxidation treatment system with continuous catalyst recycling proposed by the present invention has the following beneficial effects:

[0025] (1) The coupled wet oxidation treatment system constructed in this invention uses sodium sulfide to remove most of the copper in the wet oxygen effluent and creatively reuses the settled copper sulfide-containing slurry directly as a wet oxidation catalyst, thus establishing a closed-loop catalyst circulation system. Compared with conventional homogeneous wet oxidation catalyzed by soluble copper salts, this system does not require continuous replenishment of copper salts, significantly reducing operating costs while maintaining the wet oxygen treatment effect;

[0026] (2) In the coupled wet oxidation treatment system constructed by the present invention, copper ions in the wet oxygen effluent are mainly removed in the form of copper sulfide, and the remaining trace copper is then treated by a resin purification device to meet the standard to avoid the risk of secondary pollution. Therefore, the burden of copper removal is greatly reduced compared with the conventional solution of directly arranging a resin adsorption device at the back end of the wet oxidation, which can effectively reduce the engineering scale and investment of the resin adsorption device, and indirectly improve the feasibility of industrial application of the homogeneous catalytic wet oxygen system;

[0027] (3) In the coupled wet oxidation treatment system constructed by the present invention, the resin purification device adopts non-ion exchange chelating resin, which solves the problem of significant decline in copper removal effect of conventional cationic exchange resin in high-salinity system, increases the upper limit of salt tolerance for treated wastewater, and broadens the scope of application of catalytic wet oxidation system; aluminum hydroxide precipitation not only serves as a carrier of copper sulfide to improve the stability of slurry reuse, but its flocculation effect in the neutralization sedimentation tank can also adsorb some organic pollutants, reducing the load of subsequent resin purification device. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to further explain the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 A simplified process flow chart of a coupled wet oxidation treatment system for continuous recycling of the catalyst of the present invention;

[0030] Figure 2 This is a process roadmap for the coupled wet oxidation treatment system for continuous recycling of the catalyst of the present invention. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0032] Unless otherwise specified, the examples and comparative examples are parallel tests with the same components, component contents, preparation steps, and preparation parameters. The test methods in the following examples are conventional methods unless otherwise specified. The test materials used in the following examples are purchased from commercial channels unless otherwise specified.

[0033] Unless otherwise stated, all reagents were used as received without further purification.

[0034] Example 1:

[0035] Figure 1 The equipment and process flow of the coupled wet oxidation treatment system for continuous recycling of the catalyst described in the present invention are demonstrated.

[0036] The catalytic wet oxidation system discharges high-concentration wastewater to be treated into a homogenizing regulating tank. During the system's initial operation, catalyst is directly added to the high-concentration wastewater for uniform mixing within the homogenizing regulating tank. During subsequent operations, the copper sulfide slurry settled from the neutralization sedimentation tank is recycled back to serve as catalyst and also mixed with the high-concentration wastewater within the homogenizing regulating tank. After pH adjustment with acid / base, the mixed wastewater in the homogenizing regulating tank is pumped by a high-pressure pump to a heat exchanger for preheating before entering the catalytic wet oxidation reactor for reaction. The wet oxygen effluent is cooled by the same heat exchanger before being discharged to the neutralization sedimentation tank. After the wet oxygen effluent in the neutralization sedimentation tank cools down, alkali is added to adjust the pH, and then sodium sulfide and polyacrylamide (PAM) are added. The copper sulfide slurry and the supernatant are separated by gravity sedimentation. The copper sulfide slurry is returned to the homogenization regulating tank. The supernatant is filtered by a filtration device, and the copper concentration of the filtrate is monitored by an online monitoring and control device. If it meets the standard, it is directly discharged. If it does not meet the standard, a non-ion exchange chelating resin purification device is used for deep copper removal to ensure that it meets the standard before discharge. When the pressure of the filtration device exceeds the specified range, backwashing is carried out, and the resulting backwash liquid is returned to the neutralization sedimentation tank for treatment.

[0037] Comparative Example 1

[0038] The difference from Example 1 is that a cationic exchange resin is used to replace the non-ion exchange chelating resin, and the other details are the same.

[0039] Performance testing:

[0040] 1. Using Example 1, a test was conducted on highly concentrated wastewater from a pesticide company in Yangzhou, Jiangsu Province (COD of 33,000 mg / L, TDS of 21 g / L, and pH of 5-6). Other conditions were controlled to be the same, and the treatment effects of directly adding a soluble copper salt and refluxing the copper sulfide slurry with different catalyst forms were compared. The results are shown in Table 1 below.

[0041] Table 1

[0042] project COD (mg / L) High-concentration wastewater 33000 No catalyst added 21660 Direct addition of soluble copper salts 7853 Reflow of copper sulfide slurry (first time) 9460 Reflux of copper sulfide slurry (second time) 9211

[0043] The results show that using the reflux of copper sulfide-containing slurry as a catalyst can achieve a good catalytic effect and help accelerate the removal of COD.

[0044] 2. Using Example 1, a test was conducted on high-concentration wastewater from a dye enterprise in Lianyungang, Jiangsu Province (COD of 27,000 mg / L, TDS of 203 g / L, and pH of 12.0). Other conditions were kept consistent, and the treatment effects of directly adding a soluble copper salt and refluxing the copper sulfide slurry were compared under different catalyst forms. The results are shown in Table 2 below.

[0045] Table 2

[0046] project COD (mg / L) High-concentration wastewater 27000 No catalyst added 9658 Direct addition of soluble copper salts 3472 Reflow of copper sulfide slurry (first time) 3689 Reflux of copper sulfide slurry (second time) 3844

[0047] The results show that using the reflux of copper sulfide-containing slurry as a catalyst can achieve a good catalytic effect and help accelerate the removal of COD.

[0048] 3. Using Example 1 and Comparative Example 1, experiments were conducted using high-concentration wastewater from a pesticide company in Yangzhou, Jiangsu (COD: 33,000 mg / L, TDS: 21 g / L, pH: 5-6) and high-concentration wastewater from a dye company in Lianyungang, Jiangsu (COD: 27,000 mg / L, TDS: 203 g / L, pH: 12.0). The results are shown in Table 3 below.

[0049] Table 3

[0050] Wastewater TDS (g / L) Example 1: Cu in effluent (mg / L) Comparative Example 1 Outlet Cu (mg / L) 21 0.3 1.2 203 0.5 2.8

[0051] In Comparative Example 1, the efficiency of the cationic resin decreased under high salt conditions, and the final effluent copper concentration exceeded the standard (>0.5 mg / L). The inventive system removed most of the copper through sodium sulfide precipitation and used non-ionic resin for deep purification, thereby achieving standard discharge.

[0052] The filtrate (Cu=5 mg / L) after wet oxygen effluent filtration was treated with the resins in Example 1 and the comparative example, respectively. The results are shown in Table 4 below.

[0053] Table 4

[0054]

[0055] Under the same influent copper concentration (5 mg / L) and salt conditions, the copper removal rate of non-ion exchange chelating resin is significantly higher than that of cationic resin because its chelation effect is not inhibited by salt. A major characteristic of non-ion exchange chelating resin is its salt-promoting effect. The copper removal rate will increase with the increase of salt, which is completely opposite to that of cationic resin.

[0056] While the specific embodiments of the present invention have been described in detail above, these are merely exemplary and the present invention is not limited thereto. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, any equivalent changes and modifications made without departing from the spirit and scope of the present invention are intended to be encompassed within the scope of the present invention.

Claims

1. A coupled wet oxidation treatment system with continuous recycling of catalyst, characterized in that The invention comprises a homogenizing regulating tank, a catalytic wet oxidation reaction device, a neutralization sedimentation tank, a filtering device, an online monitoring and control device, and a resin purification device which are connected in sequence; the resin purification device is filled with non-ion exchange chelating resin, alkali and sodium sulfide are added to the neutralization sedimentation tank, and a slurry containing copper sulfide and aluminum hydroxide is obtained after sedimentation and refluxed to the homogenizing regulating tank, thereby realizing continuous recycling and reuse of the catalyst in the treatment system.

2. The processing system according to claim 1, wherein: The resin has a primary / secondary / tertiary amine or diaminomethylpyridine structure.

3. The processing system according to claim 1, wherein: The operation process of the coupled wet oxidation treatment system with continuous catalyst recycling includes the following steps: (1) During the first run, the catalyst is directly added to the homogenization regulating tank. During subsequent runs, the copper sulfide slurry settled in the neutralization sedimentation tank is recycled as a catalyst, mixed with high-concentration wastewater, and the pH is adjusted to 3-5. (2) Using a high-pressure pump to transport the mixed wastewater, the wastewater is preheated by a heat exchanger and then enters a catalytic wet oxidation reactor for reaction at 0.5-20 MPa and 120-350°C; (3) The effluent from the wet oxidation reaction is cooled by a heat exchanger and then discharged into a neutralization sedimentation tank. After cooling to below 50°C, alkali is added to adjust the pH to 6-11, and sodium sulfide and polyacrylamide are added for coagulation and sedimentation. (4) The copper sulfide slurry formed by sedimentation is returned to the homogenization regulating tank. The supernatant is filtered by a filter device and then the copper concentration is detected by an online monitoring and control device. If it meets the standard, it is directly discharged. If it exceeds the standard, it is discharged after deep copper removal by a resin purification device.

4. The processing system according to claim 3, characterized in that The catalyst added during the first operation is a mixture of copper salts and aluminum salts, wherein the copper salt is a mixture of one or more of copper nitrate, copper sulfate, copper chloride, copper carbonate, copper acetate, copper oxide, copper hydroxide, basic copper carbonate, basic copper sulfate, and copper sulfide; and the aluminum salt is a mixture of one or more of aluminum chloride, aluminum sulfate, aluminum nitrate, alum, aluminum hydroxide, polyaluminum chloride, polyaluminum sulfate, and polyaluminum chloride sulfide; and the main solid components of the copper sulfide slurry produced by gravity sedimentation in the neutralization sedimentation tank are copper sulfide and aluminum hydroxide.

5. The processing system according to claim 1, wherein: Acid / alkali is added to the mixed wastewater in the homogenization regulating tank to adjust the pH value to 3-5; the wastewater in the neutralization sedimentation tank is cooled to below 50°C, and alkali is added to adjust the pH value to 6-11, wherein the alkali is one or a mixture of ammonia water, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, and sodium bicarbonate.

6. The processing system according to claim 1, wherein: The pressure in the catalytic wet oxidation reaction device is 0.5-20 MPa, the temperature is 120-350° C., and air or oxygen is introduced as an oxidant.

7. The processing system according to claim 1, wherein: The resin filled in the resin purification device is a non-ion exchange chelating resin with a primary / secondary / tertiary amine structure or the following diaminomethylpyridine structure:

8. The processing system according to claim 1, wherein: The online monitoring and control device monitors the copper concentration C1 of the filtrate discharged from the filtration device and the copper concentration C2 of the water treated by the resin purification device.

9. The processing system according to claim 1, wherein: The conditions for the online monitoring and control device to control the deep purification treatment of the filtrate include: when the copper concentration C1 of the filtrate discharged from the filtration device is lower than the control limit concentration C0 (mg / L), the online monitoring and control device controls the reversing valve to discharge the filtrate directly.

10. The processing system according to claim 1, wherein: The conditions for controlling the deep purification treatment of the filtrate by the online monitoring and control device also include: when the copper concentration C1 of the filtrate discharged from the filtering device is higher than the control limit concentration C0, the online monitoring and control device controls the reversing valve to discharge the filtrate into the resin purification device for emergency treatment; at this time, when the copper concentration C2 of the effluent treated by the resin purification device is lower than the control limit concentration C0, the treated effluent is directly discharged; when the copper concentration C2 of the effluent treated by the resin purification device is higher than the control limit concentration C0, water intake is stopped and the resin purification device starts desorption regeneration.

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