Process for the recovery of a catalyst for catalytic wet air oxidation by membrane filtration

Abstract

The application discloses a method for recovering a catalytic wet oxidation catalyst by a membrane filtration method, and comprises the following steps: adjusting salt water after catalytic wet oxidation to be alkaline, carrying out solid-liquid separation through a filter membrane assembly, and obtaining a treatment liquid and a first solid. The filter membrane assembly of the application can effectively prevent the penetration of catalyst in the form of precipitation by using a micron ePTFE membrane, so that the catalyst ions penetrating the membrane are in the ppb level, and thus the catalyst ions can directly pass through a chelating resin tower. Meanwhile, the filter membrane assembly of the application is provided with a DCS sequential control system, through changing the filtration time, the backflush cycle, the backflush time and the like, the catalyst concentration at the conical bottom of the membrane filter shell can be directly controlled, and the catalyst concentration is much higher than that obtained by natural sedimentation, so that the disadvantages existing in the recovery of the catalyst in the existing catalytic wet oxidation reaction are solved. The membrane filtration method of the application is of great significance to improving the catalyst recovery effect of the catalytic wet oxidation method, can produce considerable economic benefits, and has high popularization and application value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wastewater treatment, and relates to a method for recovering a catalytic wet oxidation catalyst by a membrane filtration method. BACKGROUND

[0002] The wet oxidation technology is an effective method for treating toxic and harmful high-concentration organic wastewater developed in the 1950s, and the WAO research in China started in the 1980s. The WAO is a chemical process in which O2 in air is used as an oxidant to oxidize organic pollutants in liquid phase into CO2 and H2O and other inorganic small molecules or organic small molecules under high temperature and high pressure. The wet oxidation technology has the characteristics of wide application range and can effectively oxidize various types of high-concentration organic wastewater without selection.

[0003] In order to improve the oxidation efficiency of wet oxidation and the decomposition efficiency of organic matter, people have developed a catalytic wet oxidation treatment technology using high-efficiency and stable catalysts on the basis of the traditional wet oxidation technology. The technology uses oxygen-rich gas or oxygen as an oxidant, and uses the catalytic action of the catalyst to reduce the activation energy of the wet oxidation reaction, so as to accelerate the reaction between the organic matter in the wastewater and the oxidant, and then oxidize the organic matter and the poisons containing N, S and the like in the wastewater into CO2, N2, SO2 and H2O, so as to achieve the purpose of wastewater purification. The catalysts used for catalytic wet oxidation treatment can be divided into homogeneous oxidation catalysts and heterogeneous oxidation catalysts.

[0004] At present, the principle of Fenton reaction is mainly used in the operation of catalytic wet oxidation to treat organic matter in wastewater. In order to save costs, the homogeneous catalyst of Fenton reaction needs to be recycled. The wastewater after catalytic wet oxidation contains 500-5000 ppm of catalyst ions. At present, the catalyst in the wastewater is recovered by the method of precipitation + adsorption of clear liquid by chelating resin + separation of turbid liquid by centrifuge + dissolution of catalyst again, which also achieves the purpose of refining the clear liquid. Through the combination of the above three steps, the recovery of metal ions in the wastewater and the purification of metal ions in the refined water are realized. Among them: step one is to add a flocculating agent to precipitate in an alkaline environment, so that the metal ions precipitate in the catalyst settling tank; step two is to adsorb the low-concentration metal ions in the settled clear liquid by chelating resin, and the low-concentration metal ions in the supernatant in the settling tank are acidified by adjusting the pH of the salt water to ensure the state of the metal ions, and then adsorbed and intercepted by the chelating resin to achieve refinement, and the saturated resin needs to be regenerated; step three is to separate the settled turbid liquid by using a high-speed horizontal spiral centrifuge, and the precipitate after centrifugation is dissolved by acid and then reused in the wet oxidation reactor. In the actual operation of the process, the following shortcomings exist:

[0005] To achieve the settling effect, the concentration of flocculant, system processing capacity, material pH, material temperature, solution salt content and other factors need to be considered, so the operation is difficult; and in the centrifugal separation process, the change of the settling concentration will also cause the change of the load of the centrifuge, and further cause the change of the catalyst system concentration; and the chelating resin has a higher requirement for pH value, and the basic settling clear liquid will cause the difficulty in controlling the pH value in the acidification process due to the change of the metal content, and further cause the metal ion content in the refined brine to exceed the standard. Meanwhile, the copper ion content in the settling clear liquid is high, the saturation period of the chelating resin is short, and the chelating resin needs to be regenerated frequently, thereby causing the fluctuation of the material consumption and the index.

[0006] In addition, in the settling process, the flocculant is wrapped around the precipitate, and thus is easy to accumulate in the catalyst and cause fouling in the pipelines of the catalyst system storage tanks and conveying equipment, causing pipeline blockage and equipment operation failure. The flocculant in the settling clear liquid will also cause the blockage of the resin channel in the chelating resin tower and the hardening of the resin bed, thereby causing the increase of the pressure drop and the decrease of the adsorption capacity, and further causing the decrease of the resin tower flux and the adsorption capacity; and the hardening will also cause incomplete regeneration, and the clumping will also cause bridging, thereby causing the resin bed to flow and short circuit, and thus seriously restricting the brine treatment load and the index stability.

[0007] Furthermore, the natural settling is also affected by the settling speed, and the concentration of the settled catalyst is low, and the high-temperature oxidation system needs to maintain a certain amount of catalyst concentration. Therefore, a large amount of catalyst solution needs to be added, otherwise the treatment capacity of the system for organic wastewater will be reduced, and further the wastewater treatment load will be reduced. SUMMARY

[0008] To improve the above technical problems, the present application provides a method for recycling a catalytic wet oxidation catalyst, which comprises adjusting the brine after catalytic wet oxidation to be alkaline, and performing solid-liquid separation through a filter membrane assembly to obtain a treatment liquid and a first solid.

[0009] According to the embodiment of the present application, the catalyst used in the catalytic wet oxidation is copper chloride. Preferably, the concentration of copper ions in the brine after the catalytic wet oxidation is 800-2500 mg / L, preferably 1000-2000 mg / L, and more preferably 1200-1700 mg / L.

[0010] According to the embodiment of the present application, an alkali solution is added to the brine after the catalytic wet oxidation to adjust the pH value to 9.5-12, for example 9.5, 10.5, 11 or 12. For example, the alkali solution can be a NaOH solution. For another example, the concentration of the NaOH solution is 10-30 wt%, for example 10 wt%, 20 wt% or 30 wt%.

[0011] According to an embodiment of the present invention, the method further includes: mixing the first solid with an acid to regenerate the catalyst, and reusing the regenerated catalyst in catalytic wet oxidation. Preferably, the acid is hydrochloric acid. Preferably, the catalyst regeneration is carried out in a dissolving tank.

[0012] According to an embodiment of the present invention, the filter membrane assembly includes a mounting plate, mounting holes, a cylindrical filter membrane, and a backwash port. The mounting plate has a plurality of mounting holes, and a cylindrical filter membrane is installed in the mounting holes.

[0013] In one embodiment of the present invention, the cylindrical filter membrane is a micron-sized e-PTFE membrane. Preferably, the micron-sized e-PTFE membrane has a pore size of 0.1 to 0.5 μm, exemplarily 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, and 0.5 μm.

[0014] In one embodiment of the present invention, a cylindrical filter membrane with a pore size of 0.2 μm is used, and under operating conditions, its membrane flux is 0.278 m³ / m. 2 ·h、

[0015] In one embodiment of the present invention, the operating pressure of the cylindrical filter membrane is 3kPa-100kPa, exemplarily 65kPa.

[0016] In one embodiment of the present invention, the single filtration time of the cylindrical filter membrane can be 400-800 seconds, with an exemplary value of 600 seconds. The cylindrical filter membrane of the present invention can perform two consecutive filtrations followed by a single slag discharge.

[0017] In one embodiment of the present invention, the backwashing time of the filter membrane assembly is 10s-25s, exemplarily 10s, 15s, 20s, and 25s.

[0018] In one embodiment of the present invention, the backwashing cycle of the filter membrane assembly is 685s.

[0019] In this invention, the backwash pressure of the filter membrane assembly is the pressure difference generated after overcoming flow resistance, based on the height difference between the clarified liquid in the clarified liquid buffer zone at the top of the membrane filter housing and the inlet of the backwash tank. For example, the backwash pressure is 10 kPa-20 kPa.

[0020] According to an embodiment of the present invention, a membrane filter housing is provided on the outside of the membrane assembly. Preferably, the membrane assembly is embedded in the top of the membrane filter housing.

[0021] According to an embodiment of the present invention, a feed inlet is provided on one side of the bottom of the membrane filter housing, and a clear liquid outlet is provided on one side of the top of the membrane filter housing.

[0022] According to an embodiment of the present invention, an overflow port (backwash discharge port) is provided at the lower part of the membrane filter housing, and the overflow port (backwash discharge port) is connected to the backwash tank.

[0023] According to an embodiment of the present invention, the bottom of the membrane filter housing is provided with a filter cake discharge port, and a filter cake discharge valve is installed on the filter cake discharge port.

[0024] According to an embodiment of the present invention, the slag discharge cycle can be set according to the catalyst concentration and backflushing cycle in the brine after catalytic wet oxidation. For example, the slag discharge cycle can be 1470s or 1540s.

[0025] According to an embodiment of the present invention, the slag discharge time can be set according to the catalyst concentration in the brine entering the filter membrane assembly, for example, it can be 100s-180s, such as 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s, and 180s.

[0026] In this invention, the brine after catalytic wet oxidation is adjusted to alkalinity and then fed into the interior of the membrane filter housing through the feed inlet. Solid-liquid separation occurs through the cylindrical filter membrane, where copper hydroxide precipitates and is adsorbed onto the surface of the membrane. The clear liquid is discharged through the clear liquid outlet after passing through the membrane. When the filtration pressure difference is too large, failing to meet flow requirements or exceeding the pressure tolerance of the cylindrical filter membrane, backwashing is performed through the backwashing pipe. The clear liquid in the clear liquid buffer zone at the top of the membrane filter housing is used to backwash the copper hydroxide precipitate filter cake adsorbed on the surface of the cylindrical filter membrane. The backwashed clear liquid flows back to the backwash tank and then back to the initial feed unit, while the flushed copper hydroxide precipitate freely settles to the bottom of the membrane filter housing and is discharged through the filter residue outlet at the bottom of the membrane filter housing. It is then sent to the catalyst dissolution tank for dissolution and regeneration, and finally recycled back to the oxidation reactor for reuse.

[0027] According to an embodiment of the present invention, lifting lugs are provided around the center of the membrane filter housing.

[0028] According to an embodiment of the present invention, a pressure gauge is installed on one side of the top of the membrane filter housing.

[0029] According to an embodiment of the present invention, the mounting plate has a disc-shaped structure. Preferably, the mounting plate is made of titanium or other materials that are resistant to acids and alkalis and have high structural strength.

[0030] According to an embodiment of the present invention, the filter membrane assembly is further equipped with a DCS control system. The DCS control system enables automated control, allowing adjustments to parameters such as filtration time, backwash cycle, and backwash time of the filter membrane assembly based on the catalyst concentration in the brine after catalytic wet oxidation and the production load.

[0031] In this invention, the control method of the DCS control system is as follows: After the cylindrical filter membrane is acid-washed and the catalyst is regenerated (new membrane operation), it starts to operate (initial pressure difference is 3 kPa, and the operating time can be set according to the catalyst concentration in the brine entering the filter membrane assembly). When the operating time reaches the set value and / or the filter cake (first solid) gradually accumulates until the operating pressure difference reaches about 65 kPa, due to the conveying resistance and / or the strength limitation of the cylindrical filter membrane, the cylindrical filter membrane stops filtering (the single filtration operation time of the cylindrical filter membrane is generally set to 600 s), and backwashing begins (backwashing time...). After 25s, the pressure difference is restored to the initial value after backwashing, and the next filtration cycle begins. After two filtrations, a 180s slag discharge is performed. After long-term operation, if the DCS control system detects that backwashing cannot restore the cylindrical filter membrane to the initial pressure difference and / or the time taken to reach the maximum allowable pressure difference is too short, and the equipment operation cycle cannot meet the production needs, acid washing is started to remove the filter cake (first solid) or other impurities that cannot be removed by backwashing from the pores of the cylindrical filter membrane (the acid-washed solution can be re-prepared as a catalyst). The acid-washed cylindrical filter membrane is then put back into operation.

[0032] The present invention also provides a catalyst obtained by the above method.

[0033] This invention also provides the application of the above method in the catalytic wet oxidation treatment of wastewater. Preferably, it is used in the recovery of catalysts from wastewater treated by catalytic wet oxidation.

[0034] The present invention also provides a method for treating wastewater by catalytic wet oxidation, wherein the catalyst is recovered by the above method.

[0035] The beneficial effects of this invention:

[0036] (1) This invention utilizes a membrane filter assembly to recover the catalyst in catalytic wet oxidation. It only requires adjusting the pH of the brine after catalytic wet oxidation to 9.5–12, causing the copper ions in the catalyst to transform into copper hydroxide flocculent precipitate. The membrane filter assembly effectively intercepts the copper hydroxide flocculent precipitate in the brine through solid-liquid separation, allowing water and dissolved NaCl to pass through. The copper hydroxide flocculent precipitate is blocked on the outside of the membrane. After forming a filter cake, backwashing causes the cake to detach from the membrane surface. Due to its heavier weight, the detached cake quickly settles to the bottom of the cone-shaped membrane filter housing. By opening the discharge valve at the bottom of the cone, the precipitate returns to the catalyst dissolution tank for dissolution and regeneration, and is then reused in the oxidation reactor. The membrane filter assembly of this invention uses a micron-sized ePTFE membrane, which has a larger processing capacity and lower operating pressure than a precision filter with nano-sized pores, and requires no additional power, thus saving electricity and reducing equipment requirements. The water treated by this method has a metal ion content as low as 50-100 ppb, thus fully meeting the reuse standards of chlor-alkali plants.

[0037] (2) The catalyst recovery method of this invention eliminates the need for flocculants. Furthermore, the micron-sized ePTFE membrane used in the filter assembly effectively blocks the penetration of precipitated catalyst, ensuring that the permeated catalyst ions are at the ppb level, meeting the required specifications. Therefore, it can directly bypass the chelating resin tower. Simultaneously, the filter assembly of this invention is equipped with a DCS sequential control system. By changing the filtration time, backwash cycle, and backwash time, the catalyst concentration at the bottom of the cone of the membrane filter housing can be directly controlled, and is significantly higher than the catalyst concentration obtained from natural sedimentation. This solves the drawbacks of existing catalyst recovery methods in catalytic wet oxidation reactions. The membrane filtration method of this invention is of great significance for improving the catalyst recovery effect of catalytic wet oxidation, generating considerable economic benefits and possessing high promotion and application value. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the overall structure of the filter membrane assembly of the present invention;

[0039] Figure 2 This is a side view of the filter membrane assembly;

[0040] Figure 3 This is a top view of the filter membrane assembly;

[0041] Figure 4 This is a process flow diagram of the membrane filtration method for recovering catalytic wet oxidation catalysts according to the present invention;

[0042] Figure 5 A surface condition diagram of a cylindrical filter membrane after 1300 minutes of operation;

[0043] Figure 6 A diagram showing the surface condition of a cylindrical filter membrane after acid washing following 1300 minutes of operation.

[0044] Figure 7 Cu was detected in the clarified liquid after filtration through a cylindrical membrane filter for 1300 minutes. 2+ The results of other metal ion content (μg / L) are shown in the graph;

[0045] The following are the labels in the diagram: 1. Membrane filter housing; 2. Inlet; 3. Membrane assembly; 4. Clear liquid outlet; 5. Overflow port; 6. First loose flange; 7. Connecting pipe; 8. Second loose flange; 9. Backwash tank; 10. Mounting plate; 11. Mounting hole; 12. Cylindrical filter membrane; 13. Backwash port. Detailed Implementation

[0046] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0047] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0048] Example 1

[0049] Wastewater from the saponification process of the epichlorohydrin unit (with a salt content of 19 wt%, a TOC concentration of 3500 mg / L, and a pH of 12) is catalytically wet-oxidized to produce brine (with a salt content of 19 wt%, a pH of 1, and a copper ion content of 1722008 μg / L). The pH of the brine is adjusted to 11 using a 20 wt% caustic soda solution, causing the copper ions in the brine to precipitate as copper hydroxide. The brine is then fed into the membrane filter housing 1 through inlet 2 via a feed pump. Inside the membrane filter housing 1, the brine passes through a cylindrical filter membrane 12 (using an ePTFE membrane with a pore size of 0.2 μm, operating pressure increased from 3 kPa to 65 kPa, and filtration time of 600 s). The copper hydroxide precipitate is adsorbed on the surface of the cylindrical filter membrane 12. The qualified clear liquid passes through the cylindrical filter membrane 12 and is discharged from the clear liquid outlet 4 and buffered in the clear liquid buffer zone at the top of the membrane filter housing 1. The feed pump is shut off, and the shut-off valve between the overflow port 5 and the backwash tank 9 is opened instantly. The clear liquid in the clear liquid buffer at the top of the membrane filter housing 1 backwashes the copper hydroxide precipitate adsorbed on the surface of the cylindrical filter membrane 12 using the liquid level difference (the backwash pressure difference is about 10 kPa, the backwash time is 25 s, and the backwash cycle is 685 s). The backwash washes the copper hydroxide precipitate filter cake on the cylindrical filter membrane 12 down and allows it to settle freely to the bottom of the membrane filter housing 1. It is then discharged through the slag discharge port at the bottom of the membrane filter housing 1 (the slag discharge cycle is 1470 s, and the slag discharge time is 110 s) and sent to the catalyst dissolution tank. After dissolving it with 30 wt% concentrated hydrochloric acid, the regenerated catalyst is obtained. The regenerated catalyst is recycled to the catalytic wet oxidation reactor for reuse.

[0050] The Cu in the clear liquid discharged through the clear liquid outlet 4 after filtration 2+ The contents of other metal ions (μg / L) are shown in Table 1 below.

[0051] Table 1

[0052]

[0053] Example 2

[0054] Compared with Example 1, the only difference is that the pH of the brine was adjusted to 12 using a 20wt% sodium hydroxide solution; the copper ion feed concentration was 2023000 μg / L, and the rest were the same as in Example 1.

[0055] The Cu in the clear liquid discharged through the clear liquid outlet 4 after filtration 2+ The contents of other metal ions (μg / L) are shown in Table 2 below.

[0056] Table 2

[0057]

[0058] Example 3

[0059] Compared with Example 1, the difference is that the pH of the brine was adjusted to 9.5 using a 20wt% sodium hydroxide solution; the copper ion feed concentration was 1,223,000 μg / L, and the rest were the same as in Example 1.

[0060] The Cu in the clear liquid discharged through the clear liquid outlet 4 after filtration 2+ The contents of other metal ions (μg / L) are shown in Table 3 below.

[0061] Table 3

[0062]

[0063]

[0064] The above experimental results show that after filtration by the cylindrical filter membrane of this invention, the copper ion concentration in the brine after catalytic wet oxidation can be reduced from 2000 ppm to below 100 ppb. Excessively high pH values ​​will shorten the backwash cycle, reduce the processing capacity of the cylindrical filter membrane, and cause alkali waste, increasing the cost of catalyst recovery. However, when the pH is below 9, the flocculent precipitate formed by copper ions will clog the membrane pores and cannot be removed by backwashing, thus reducing the processing capacity of the cylindrical filter membrane.

[0065] Example 4

[0066] The cylindrical filter membrane was operated during the daytime from July 8th to July 26th, 2024 (operating conditions were the same as in Example 1), with a total filtration time of 1300 minutes and a total filtered liquid volume of approximately 6.6 m³. After each filtration cycle of the cylindrical filter membrane lasting up to 1 hour, the Cu content in the clear liquid discharged from outlet 4 was measured. 2+ The content of other metal ions (μg / L) was as follows: Figure 7As shown in the figure, the cylindrical filter membrane of the present invention has a good and stable separation and recovery effect on copper hydroxide. After continuous operation and filtration, the copper ion content in the clarified liquid is all below 40 ppb, and the content of other ions is also all within the range of the effluent indicators of the epichlorohydrin section, and the effluent quality is stable.

[0067] Figure 5 The image shows the surface state of the cylindrical filter membrane after 1300 minutes of operation. As can be seen from the image, a very thin layer of filter cake has been deposited on the surface of the cylindrical filter membrane.

[0068] Figure 6 The image shows the surface state of the cylindrical filter membrane after 1300 minutes of operation and acid washing with 10wt% hydrochloric acid. As can be seen from the image, the surface of the cylindrical filter membrane returned to its original state after acid washing, and the acid washing effect was obvious. It can be reused for catalyst recovery and reuse to reduce wastewater treatment costs, which has considerable economic benefits and promotion and application value.

[0069] Example 5

[0070] The cylindrical filter membrane filtered in Example 1 was soaked in high-concentration epichlorohydrin saponification wastewater (TOC concentration of organic matter was 3500 ppm) for one week. After soaking, the cylindrical filter membrane was filtered again according to the method in Example 1. The Cu in the filtered clear liquid was... 2+ The concentration is less than 100 ppb, which indicates that the cylindrical filter membrane of the present invention has the ability to withstand organic wastewater with concentrations below 3500 ppm and has excellent resistance to production abnormalities.

[0071] In summary, compared to nanofiltration membranes, the membrane module of this invention only requires an operating pressure of less than 100 kPa, thus having lower equipment requirements and lower energy consumption. Furthermore, the quality of the effluent (low metal ion content) is significantly better than existing nanofiltration methods. Simultaneously, by employing an e-PTFE membrane, which is resistant to organic swelling, the membrane module of this invention has lower requirements for influent water quality (TOC content) than nanofiltration membranes (industrial verification shows that the cylindrical membrane of this invention can withstand epichlorohydrin saponification wastewater with TOC < 3500 ppm). Therefore, it is suitable for catalyst recovery treatment of wastewater with different TOC contents and has broad application prospects.

[0072] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of recovering a catalytic wet air oxidation catalyst, characterized by, The method comprises adjusting the salt water after catalytic wet oxidation to alkaline, separating the treated liquid and the first solid through a filter membrane assembly, mixing the first solid with hydrochloric acid to regenerate the catalyst, and recycling the regenerated catalyst to the catalytic wet oxidation; The catalyst used in the catalytic wet oxidation is copper chloride; The concentration of copper ions in the salt water after the catalytic wet oxidation is 800-2500 mg / L; An alkali solution is added to the salt water after the catalytic wet oxidation to adjust the pH to 9.5-12; The filter membrane assembly comprises a mounting plate, mounting holes, cylindrical filter membranes, and backwashing ports. The filter membrane assembly is further provided with a DCS control system. The control method of the DCS control system is as follows: when the cylindrical filter membranes start to operate after completing the catalyst regeneration through acid washing, the operation time reaches the set value, and / or the first solid gradually accumulates to an operating pressure difference of about 65 kPa, the cylindrical filter membranes stop filtering due to the limitation of the conveying resistance and / or the strength of the cylindrical filter membranes, backwashing is started, the initial pressure difference is restored after the backwashing is completed, the next filtering period is started, and 180 s of residue discharge is performed after two times of filtering; after a long time of operation, if the DCS control system monitors that the backwashing cannot restore the cylindrical filter membranes to the initial pressure difference and / or the operation time to the highest allowable pressure difference is too short, the equipment operation period cannot meet the production needs, acid washing is started to make the first solid or other impurities in the pores of the cylindrical filter membranes fall off which cannot be removed through backwashing, and the cylindrical filter membranes after the acid washing are put into operation again. The cylindrical filter membranes are micron-level e-PTFE membranes, and the pore size of the micron-level e-PTFE membranes is 0.1-0.5 μm. The operating pressure of the cylindrical filter membranes is 3-100 kPa. The single filtering time of the cylindrical filter membranes is 400-800 s. The backwashing time of the filter membrane assembly is 10-25 s. The backwashing pressure is 10-20 kPa.

2. The method of claim 1, wherein, The concentration of copper ions in the salt water after the catalytic wet oxidation is 1000-2000 mg / L.

3. The method of claim 1, wherein, The alkali solution is a NaOH solution.

4. The method of claim 3, wherein, The concentration of the NaOH solution is 10-30 wt%.

5. The method according to any one of claims 1 to 4, characterized in that, The filter membrane assembly is externally provided with a membrane filter shell, and the filter membrane assembly is embedded and installed at the top of the membrane filter shell.

6. The method of claim 5, wherein, One side of the bottom of the membrane filter shell is provided with a feed inlet, and one side of the top of the membrane filter shell is provided with a clear liquid discharge outlet.

7. The method of claim 5, wherein, The lower part of the membrane filter shell is provided with a backwashing discharge port, and the backwashing discharge port is connected with a backwashing tank.

8. The method of claim 5, wherein, The bottom of the membrane filter shell is provided with a filter residue discharge port, and a filter residue discharge valve is installed on the filter residue discharge port.

9. The method according to any one of claims 6 to 8, wherein, Lifting ears are arranged around the middle part of the membrane filter shell.

10. The method according to any one of claims 6 to 8, wherein, A pressure gauge is installed on one side of the top of the membrane filter shell.

11. The method of claim 1, wherein, The mounting plate is in a disc shape.

12. The use of the method of any one of claims 1-11 in the recovery of a catalyst in the treatment of wastewater through catalytic wet oxidation.

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