A method for treating pickling wastewater based on resource recovery

Abstract

This invention relates to the field of wastewater treatment and provides a method for treating acid pickling wastewater based on resource recovery, comprising the following steps: Step 1, pretreating the acidic wastewater to obtain nanofiltration stock solution; Step 2, introducing the nanofiltration stock solution into a nanofiltration separation device, which includes nanofiltration separation unit 1 and nanofiltration separation unit 2; the nanofiltration stock solution first enters nanofiltration separation unit 1 for iron-zinc separation, obtaining nano-concentrated solution 1 and nanofiltrate 1; nano-concentrated solution 1 enters nanofiltration separation unit 2 for iron-zinc enrichment and concentration, obtaining nano-concentrated solution 2 and nanofiltrate 2, and nanofiltrate 2 is returned to nanofiltration separation unit 1; Step 3, nanofiltrate 1 enters membrane distillation separation unit 1 for zinc and hydrochloric acid separation, obtaining membrane distillation concentrate 1 and membrane distillation acid product 1. This invention provides a simple and easy-to-operate method for treating acid pickling wastewater that does not require the addition of large amounts of reagents and is suitable for the separation of iron, zinc, and hydrochloric acid and the enrichment of iron and zinc.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment engineering technology, and specifically to a method for treating pickling wastewater based on resource recovery. Background Technology

[0002] Galvanizing steel surfaces is a crucial method of steel surface treatment. When galvanizing fails, pickling is required, generating substantial amounts of pickling wastewater. This wastewater contains high concentrations of hydrochloric acid, divalent zinc, divalent iron, and small amounts of trivalent iron, possessing potential for utilization and recycling. However, the difficulty in separating iron and zinc, coupled with the high concentration of hydrochloric acid further complicates treatment, hindering the resource recovery and reuse of this type of wastewater. Therefore, achieving the separation of iron, zinc, and hydrochloric acid from wastewater containing high concentrations of hydrochloric acid, and the enrichment of iron and zinc, is of significant practical importance.

[0003] Currently, the main methods for treating acidic wastewater include neutralization, sulfide precipitation, and extraction. However, these methods require the addition of large amounts of reagents and all have certain limitations. For example, neutralization requires the addition of a large amount of alkali, leading to a waste of acid resources and producing a large amount of difficult-to-treat waste residue, which can easily cause secondary pollution. Sulfide precipitation, on the other hand, has no effect on iron precipitation and produces highly toxic hydrogen sulfide gas. Extraction requires high-quality extractants and is a complex and difficult process to operate. For instance, the treatment method for zinc- and iron-containing waste acid proposed in patent CN103539302A requires the waste liquid to be reduced with a reducing agent for more than 12 hours, followed by the addition of concentrated sulfuric acid and evaporation and concentration at 90-110°C to replace the hydrochloric acid in the waste liquid. The vapor is then condensed to obtain hydrochloric acid, and the solution is then centrifuged and filtered at 70-100°C to obtain zinc sulfate and ferrous sulfate. The overall process is complex, requires the addition of multiple reagents, and involves high operating temperatures, posing certain safety risks.

[0004] Therefore, it is essential and of great significance to provide a simple and easy-to-operate method that does not require the addition of large amounts of reagents and is suitable for the separation of iron, zinc, and hydrochloric acid, and for the enrichment of iron and zinc. This method will help solve the problem of treating acidic wastewater containing iron and zinc and realize the resource recycling of acidic wastewater. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention aims to provide a method for treating pickling wastewater based on resource recovery. To solve these problems, this invention employs the following technical solution:

[0006] A method for treating pickling wastewater based on resource recovery includes the following steps:

[0007] Step 1: Pre-treat the acidic waste liquid to obtain nanofiltration stock solution;

[0008] Step 2: The nanofiltration solution is introduced into the nanofiltration separation device, which includes nanofiltration separation unit 1 and nanofiltration separation unit 2. Both nanofiltration separation unit 1 and nanofiltration separation unit 2 are equipped with nanofiltration membranes.

[0009] The nanofiltration solution first enters the nanofiltration separation unit 1 for iron and zinc separation, yielding nano-concentrated solution 1 and nanofiltration solution 1.

[0010] The first nano-concentrated solution is fed into the second nanofiltration separation unit for iron and zinc enrichment and concentration, resulting in the second nano-concentrated solution and the second nanofiltrate. The second nanofiltrate is then returned to the first nanofiltration separation unit.

[0011] Step 3: The nanofiltration solution is fed into the membrane distillation separation device for zinc and hydrochloric acid separation to obtain the membrane distillation concentrate and the membrane distillation acid product.

[0012] Step 4: The concentrated sodium solution 2 is introduced into the membrane distillation separation device 2 to separate iron and zinc from hydrochloric acid, resulting in membrane distillation concentrate 2 and membrane distillation acid product 2. Both membrane distillation separation device 1 and membrane distillation separation device 2 are equipped with hydrophobic membranes.

[0013] Step 5: Allow membrane distillation concentrate 1 to enter subsequent process 1, and allow membrane distillation concentrate 2 to enter subsequent process 2.

[0014] Preferably, in step one, the acidic waste liquid is pretreated using a pretreatment device. The pretreatment device includes a base, a sedimentation tank, and a pump body. The sedimentation tank and the pump body are both fixedly connected to the base. The sedimentation tank has a cavity, and a stirring assembly is connected to the inner wall of the cavity. A flocculant additive is fixedly connected to the inner wall of the cavity, and the flocculant additive is filled with flocculant. An inlet pipe and a transfer pipe are fixedly connected to the sedimentation tank. The transfer pipe is fixedly connected to the pump body, and a grid is connected to the inner wall of the transfer pipe.

[0015] Preferably, the drive assembly includes a first gear, a first sprocket, a chain, a second sprocket, a second gear, and a first servo motor. The first gear is rotatably connected to the mounting plate and meshes with the rack. The first sprocket is fixedly connected to the first gear. A transmission cavity is provided on the sedimentation tank. The bottom wall of the cavity is connected to the bottom wall of the sedimentation tank through a waste removal channel. The first servo motor is fixedly connected to the inner wall of the transmission cavity. The second gear is fixedly connected to the output shaft of the first servo motor. The second sprocket is fixedly connected to the second gear and is connected to the first sprocket via a chain. A toothed plate is slidably connected to the inner wall of the transmission cavity. The toothed plate meshes with the second gear and extends into the waste removal channel. A collection net is slidably connected to the bottom wall of the cavity. The second servo motor is fixedly connected to the sedimentation tank. A threaded rod is rotatably connected to the inner wall of the cavity. The threaded rod is fixedly connected to the output shaft of the second servo motor. A threaded hole is provided on the collection net, and the threaded rod and the inner wall of the threaded hole are threadedly connected.

[0016] Preferably, an extension bar is fixedly connected to the second gear, a sliding plate and a striking rod are slidably connected to the inner wall of the transmission cavity, the sliding plate and the striking rod are fixedly connected, the sliding plate is connected to the inner wall of the transmission cavity through the second spring, a vibrating element is fixedly connected to the top wall of the transmission cavity, the top wall of the vibrating element extends to the bottom wall of the box cavity, a roller is rotatably connected to the extension bar, one end of the striking rod is curved, and the vibrating element is provided with a curved surface.

[0017] Preferably, the nanofiltration membrane arrangement ratio in the first nanofiltration separation unit is 2~2.2:1, and the nanofiltration membrane arrangement ratio in the second nanofiltration separation unit is 2~2.2:1.

[0018] Preferably, the nanofiltration membrane material includes one or more of polyamide, polysulfonamide, polysulfonamide-polyamine, polyamine, polyurea, and sulfonated polyether ether ketone.

[0019] Preferably, the nanofiltration membrane is one of positively charged, negatively charged, or Janus nanofiltration membrane.

[0020] Preferably, the hydrophobic membrane is one of a polysulfonamide acid-resistant nanofiltration membrane, a polyamine acid-resistant nanofiltration membrane, or a polytetrafluoroethylene hydrophobic membrane.

[0021] Preferably, the first nanofiltration solution is heated to 53°C before entering the first membrane distillation separation device, and the second nanoconcentrate solution is heated to 53°C before entering the second membrane distillation separation device.

[0022] Preferably, both the first and second subsequent processes include one or more of solvent extraction, electrolysis, precipitation, ion exchange resin, and ion exchange membrane to further realize the recycling of metals.

[0023] The present invention has the following beneficial effects:

[0024] This invention targets acidic wastewater and employs acid-resistant nanofiltration membranes made of polysulfonamide, polyamine, or polytetrafluoroethylene. The nanofiltration separation device uses a circulating system to increase the iron-zinc concentration ratio during the nanofiltration stage. Controlling the concentration ratio of the nanofiltration membrane controls the quality of the effluent, reducing the enrichment and recovery of zinc by iron impurities. Controlling the operating pressure of the nanofiltration system ensures a certain flux and separation efficiency, minimizing overall costs. This invention achieves the enrichment, separation, and recovery of iron and zinc from high-concentration acidic wastewater with low metal ion concentrations, without the need for large amounts of reagents, reducing secondary pollution. It rationally utilizes the advantages of different membrane technologies and achieves efficient separation and resource recovery of metal ions and acids. Attached Figure Description

[0025] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0026] Figure 1 This is a flowchart of a pickling wastewater treatment method based on resource recycling according to the present invention;

[0027] Figure 2 This is a schematic diagram of the pretreatment device in a pickling wastewater treatment method based on resource recovery according to the present invention.

[0028] Figure 3 This is the present invention. Figure 2 Enlarged view of point A in the middle;

[0029] Figure 4 This is the present invention. Figure 2 Enlarged view of point A in the middle;

[0030] Figure 5 This is the present invention. Figure 2 Left view of the central fluid transfer pipe, grid, permanent magnet plate, and rack.

[0031] Reference numerals: 1. Base; 2. Sedimentation tank; 3. Tank cavity; 4. Inlet pipe; 5. Transfer pipe; 6. Pump body; 7. Grille; 8. Permanent magnet plate; 9. Rack; 10. Mounting plate; 11. Recovery tank; 12. Extension rod; 13. Permanent magnet strip; 14. Spring 1; 15. Cleaning brush; 16. Gear 1; 17. Sprocket 1; 18. Chain; 19. Sprocket 2; 20. Gear 2; 21. Extension strip; 22. Roller; 23. Servo motor 1; 24. Gear plate; 25. Transmission cavity; 26. Impurity discharge channel; 27. Sliding plate; 28. Spring 2; 29. ​​Impact rod; 30. Vibrating component; 31. Servo motor 2; 32. Threaded rod; 33. Collection screen; 34. Flocculant additive; 35. Stirring assembly. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, it should be noted that the terms "vertical," "upper," "lower," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or a connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] like Figure 1 As shown, a method for treating pickling wastewater based on resource recovery includes the following steps:

[0036] Step 1: Pre-treat the acidic waste liquid to obtain nanofiltration stock solution;

[0037] Step 2: The nanofiltration solution is introduced into the nanofiltration separation device, which includes nanofiltration separation unit 1 and nanofiltration separation unit 2. Both nanofiltration separation unit 1 and nanofiltration separation unit 2 are equipped with nanofiltration membranes.

[0038] The nanofiltration solution first enters the nanofiltration separation unit 1 for iron and zinc separation, yielding nano-concentrated solution 1 and nanofiltration solution 1.

[0039] The main components of nanofiltration solution 1 are divalent zinc and hydrochloric acid, with a zinc ion concentration of 1 g / L and a ferrous ion concentration of 0.05 g / L.

[0040] The first nano-concentrated solution is fed into the second nanofiltration separation unit for iron and zinc enrichment and concentration, resulting in the second nano-concentrated solution and the second nanofiltration solution. The concentration of ferrous ions in the second nano-concentrated solution is 1 g / L, and the concentration of zinc ions is 1 g / L. The second nanofiltration solution is refluxed back to the first nanofiltration separation unit.

[0041] Step 3: The nanofiltration solution is fed into the membrane distillation separation device for zinc and hydrochloric acid separation to obtain the membrane distillation concentrate and the membrane distillation acid product.

[0042] Step 4: The concentrated sodium solution 2 is introduced into the membrane distillation separation device 2 to separate iron and zinc from hydrochloric acid, resulting in membrane distillation concentrate 2 and membrane distillation acid product 2. Both membrane distillation separation device 1 and membrane distillation separation device 2 are equipped with hydrophobic membranes.

[0043] Step 5: Produce membrane distillation concentrate 1 into subsequent process 1, and proceed with membrane distillation concentrate 2 into subsequent process 2.

[0044] In an optional embodiment of the present invention, in step one, the acidic waste liquid is pretreated using a pretreatment device. The pretreatment device includes a base 1, a sedimentation tank 2, and a pump body 6. The sedimentation tank 2 and the pump body 6 are both fixedly connected to the base 1. The sedimentation tank 2 has a cavity 3. A stirring assembly 35 is connected to the inner wall of the cavity 3. A flocculant additive 34 is fixedly connected to the inner wall of the cavity 3. The flocculant additive 34 is filled with flocculant. An inlet pipe 4 and a transfer pipe 5 are fixedly connected to the sedimentation tank 2. The transfer pipe 5 is fixedly connected to the pump body 6. A grid 7 is connected to the inner wall of the transfer pipe 5.

[0045] In an optional embodiment of the present invention, the drive assembly includes a gear 16, a sprocket 17, a chain 18, a second sprocket 19, a second gear 20, and a servo motor 23. Gear 16 is rotatably connected to the mounting plate 10 and meshes with the rack 9. The sprocket 17 is fixedly connected to gear 16. A transmission cavity 25 is provided on the sedimentation tank 2. The bottom wall of the chamber 3 communicates with the bottom wall of the sedimentation tank 2 through a waste discharge channel 26. The servo motor 23 is fixedly connected to the inner wall of the transmission cavity 25, and the second gear 20 is fixedly connected to the transmission cavity 23. On the output shaft, sprocket 219 is fixedly connected to gear 20. Sprocket 219 is connected to sprocket 17 via chain 18. A toothed plate 24 is slidably connected to the inner wall of the transmission cavity 25. The toothed plate 24 meshes with gear 20. The toothed plate 24 extends into the waste discharge channel 26. A collection net 33 is slidably connected to the bottom wall of the box cavity 3. A servo motor 21 is fixedly connected to the sedimentation tank 2. A threaded rod 32 is rotatably connected to the inner wall of the box cavity 3. The threaded rod 32 is fixedly connected to the output shaft of servo motor 21. A threaded hole is opened on the collection net 33. The threaded rod 32 is threadedly connected to the inner wall of the threaded hole.

[0046] In an optional embodiment of the present invention, an extension bar 21 is fixedly connected to the gear 20, a sliding plate 27 and a striking rod 29 are slidably connected to the inner wall of the transmission cavity 25, the sliding plate 27 and the striking rod 29 are fixedly connected, the sliding plate 27 is connected to the inner wall of the transmission cavity 25 through a spring 28, a vibrating element 30 is fixedly connected to the top wall of the transmission cavity 25, the top wall of the vibrating element 30 extends to the bottom wall of the box cavity 3, a roller 22 is rotatably connected to the extension bar 21, one end of the striking rod 29 is curved, and the vibrating element 30 is provided with a curved surface.

[0047] In an optional embodiment of the present invention, the nanofiltration membrane arrangement ratio in the first nanofiltration separation unit is 2~2.2:1, and the nanofiltration membrane arrangement ratio in the second nanofiltration separation unit is 2~2.2:1. Optimizing the arrangement ratio of the nanofiltration membranes is beneficial to improving the separation performance and hydrodynamic efficiency of the membrane module, ensuring a high iron-zinc separation effect while guaranteeing flux, thereby improving the iron-zinc concentration efficiency and the quality of the produced water.

[0048] In an optional embodiment of the present invention, the nanofiltration membrane material includes one or more of polyamide, polysulfonamide, polysulfonamide-polyamine, polyamine, polyurea, and sulfonated polyether ether ketone, which effectively adapts to the corrosive environment of acidic waste liquid, improves the chemical resistance and selectivity of the membrane material, and enhances the adaptability and operational reliability of the membrane separation system.

[0049] In one optional embodiment of the present invention, the nanofiltration membrane is one of positively charged, negatively charged, or Janus nanofiltration membrane. By selecting nanofiltration membranes with different charge characteristics, the separation performance of charged metal ions such as iron and zinc can be enhanced in a targeted manner, the selective retention efficiency of the membrane can be improved, and the membrane system can be flexibly configured according to the composition of wastewater to enhance the applicability of the process.

[0050] In one optional embodiment of the present invention, the hydrophobic membrane is one of polysulfonamide acid-resistant nanofiltration membrane, polyamine acid-resistant nanofiltration membrane, or polytetrafluoroethylene hydrophobic membrane, ensuring that membrane distillation separation device one and membrane distillation separation device two still have excellent chemical stability and hydrophobicity in high acid and high salt environments, thereby improving membrane distillation efficiency and extending service life.

[0051] In an optional embodiment of the present invention, since the membrane distillation temperature of nanofiltrate one needs to be 50-80°C, nanofiltrate one is heated to 53°C before entering the membrane distillation separation device one. Since the membrane distillation temperature of nanofiltrate two needs to be 50-80°C, nanofiltrate two is heated to 53°C before entering the membrane distillation separation device two. This provides sufficient vapor pressure difference driving force for membrane distillation, improves the separation efficiency of acid and metal ions, and controls the temperature within a safe range to avoid damage to the membrane material caused by high temperature.

[0052] In one optional embodiment of the present invention, the operating pressure of the nanofiltration separation unit is 5~40 bar, which effectively ensures the balance between nanofiltration flux and concentration efficiency, realizes efficient preliminary separation of iron and zinc, and lays the foundation for subsequent enrichment and resource recovery.

[0053] In one optional embodiment of the present invention, the operating pressure of the nanofiltration separation unit two is 5~30 bar, which helps to stably control the mass transfer efficiency and membrane operating pressure during the enrichment and concentration process, ensuring economical system operation and maintaining high iron and zinc concentration output.

[0054] In an optional embodiment of the present invention, both the first and second subsequent processes include one or more of solvent extraction, electrolysis, precipitation, ion exchange resin, and ion exchange membrane, to further realize the recycling of metals. They can be flexibly combined according to actual needs to achieve high-purity recovery and utilization of zinc and iron, enhance resource utilization efficiency, and reduce the residual burden of waste liquid treatment.

[0055] This invention targets acidic wastewater and employs acid-resistant nanofiltration membranes made of polysulfonamide, polyamine, or polytetrafluoroethylene. The nanofiltration separation device uses a circulating system to increase the iron-zinc concentration ratio during the nanofiltration stage. Controlling the concentration ratio of the nanofiltration membrane controls the quality of the effluent, reducing the enrichment and recovery of zinc by iron impurities. Controlling the operating pressure of the nanofiltration system ensures a certain flux and separation efficiency, minimizing overall costs. This invention achieves the enrichment, separation, and recovery of iron and zinc from high-concentration acidic wastewater with low metal ion concentrations, without the need for large amounts of reagents, reducing secondary pollution. It rationally utilizes the advantages of different membrane technologies and achieves efficient separation and resource recovery of metal ions and acids.

[0056] Pretreatment device implementation process: Acidic wastewater is added into the chamber 3 through the inlet pipe 4. The flocculant additive 34 is controlled by the electric valve 1 to add flocculant to the acidic wastewater. The stirring component 35 is turned on to stir the acidic wastewater, so that the impurities in the water can be better coagulated into large particles. The stirring component 35 is turned off to allow the large particles to settle on the bottom wall of the chamber 3. The servo motor 31 is turned on to drive the threaded rod 32 to rotate, so that the left wall of the collection screen 33 moves to the left above the discharge channel 26. The collection screen 33 and the vibrating component 30 are against each other. The collection screen 33 pushes the large particles to fall into the discharge channel 26. The electric valve 2 on the transfer pipe 5 is opened to turn on the pump body 6. The pump body 6 draws the acidic wastewater and uses it as nanofiltration raw material to enter the nanofiltration separation device. When the acidic wastewater passes through the grid 7 on the transfer pipe 5, the grid 7 can intercept small particles of impurities, so that most of the particulate impurities are removed from the acidic wastewater.

[0057] After most of the acidic wastewater in chamber 3 is pumped out (a small amount of wastewater will remain in chamber 3), the servo motor 23 is activated, driving gear 20, extension bar 21, sprocket 29, chain 18, sprocket 17, and gear 16 to rotate. Gear 20 drives the toothed plate 24 to move to the right into the transmission chamber 25. The left wall of the toothed plate 24 disengages from the left wall of the discharge channel 26, thus relieving the blockage. Large particles of impurities in the discharge channel 26 fall outside the sedimentation tank 2. Users can use other containers to collect these large particles. Gear 16 drives the rack 9, permanent magnet plate 8, and grid 7 to move upwards. When the permanent magnet plate 8 moves to the left of the permanent magnet strip 13, the bottom wall of the grid 7 is higher than the top wall of the recovery tank 11. The grid 7 does not come into contact with the bristles of the cleaning brush 15. The permanent magnet plate 8 magnetically attracts the permanent magnet strip 13, thus... The permanent magnet strip 13, extension rod 12, and recycling box 11 move to the left against the elastic force of spring 14. The left wall of recycling box 11 moves to the left of the left wall of grid 7. Grid 7 and permanent magnet plate 8 continue to move upwards. Permanent magnet plate 8 continues to attract permanent magnet strip 13. The bristles of cleaning brush 15 abut against grid 7 to wipe and clean grid 7. Impurities on grid 7 fall into recycling box 11 for collection. Extension rod 21 drives roller 22 to push slide plate 27 to the left against spring 28. Impact rod 29 moves back and forth left and right under the pushing force of roller 22 and the elastic force of spring 28, thus impacting vibrating element 30 multiple times. The vibration of vibrating element 30 is transmitted to collection net 33. Some impurities on collection net 33 are shaken into the waste discharge channel 26 and fall outside sedimentation tank 2, thereby reducing impurities adhering to collection net 33.

[0058] Reversing the servo motor 23 will cause the toothed plate 24 to block the waste discharge channel 26 again. After the permanent magnet plate 8 moves down to the point where it is lower than the permanent magnet strip 13, the recovery box 11 moves to the right and resets under the elastic force of the spring 14 to prevent the grid 7 from moving down. The grid 7 is then smoothly reinserted into the liquid transfer pipe 5, completing the automatic cleaning.

[0059] The pretreatment device has the following beneficial effects:

[0060] Acidic wastewater is introduced through the inlet pipe 4, and flocculant is automatically added with the flocculant adder 34. With the full stirring of the stirring component 35, the suspended impurities in the wastewater can be quickly flocculated into large particles, which facilitates subsequent sedimentation and separation treatment.

[0061] Large particles of impurities after sedimentation are collected and removed by the collection net 33 and the vibrating element 30. Under the drive of the threaded rod 32 driven by the second servo motor 31, the collection net 33 can move directionally to the top of the impurity discharge channel 26. Combined with the impact vibration of the vibrating element 30, the adhering impurities are efficiently peeled off, greatly reducing the frequency of manual cleaning.

[0062] The inner wall of the liquid transfer tube 5 is equipped with a grid 7, which can effectively intercept residual small particulate impurities, ensure the quality of the feed liquid in the subsequent nanofiltration separation process, and extend the service life of the membrane module.

[0063] The grid 7, combined with the permanent magnet plate 8, rack 9 and recycling bin 11, can achieve automatic lifting and cleaning under the linkage of the drive components. After the cleaning brush 15 brushes the surface of the grid 7, the impurities can fall directly into the recycling bin 11 for centralized collection, avoiding blockage and achieving automated maintenance. The recycling bin 11 can be moved at the appropriate time to complete the collection of impurities without blocking the operation of other components.

[0064] The roller 22 on the extension strip 21 repeatedly strikes the slide plate 27 and the impact rod 29 during the movement, causing the impact rod 29 to reciprocate and strike the vibrating element 30. The vibration further removes residual micro-impurities on the collection net 33, improving the thoroughness of cleaning.

[0065] Multiple components work together to achieve functions such as automatic cleaning, automatic waste removal, and automatic descaling of the grid 7, which greatly reduces manual intervention, lowers operation and maintenance costs, and improves the continuity and stability of the equipment operation.

[0066] The components, modules, mechanisms, and devices in this invention that are not described in detail are all general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for treating pickling wastewater based on resource recovery, characterized in that, Includes the following steps: Step 1: Pre-treat the acidic waste liquid to obtain nanofiltration stock solution; Step 2: The nanofiltration solution is introduced into the nanofiltration separation device, which includes nanofiltration separation unit 1 and nanofiltration separation unit 2. Both nanofiltration separation unit 1 and nanofiltration separation unit 2 are equipped with nanofiltration membranes. The nanofiltration solution first enters the nanofiltration separation unit 1 for iron and zinc separation, yielding nano-concentrated solution 1 and nanofiltration solution 1. The first nano-concentrated solution is fed into the second nanofiltration separation unit for iron and zinc enrichment and concentration, resulting in the second nano-concentrated solution and the second nanofiltrate. The second nanofiltrate is then returned to the first nanofiltration separation unit. Step 3: The nanofiltration solution is fed into the membrane distillation separation device for zinc and hydrochloric acid separation to obtain the membrane distillation concentrate and the membrane distillation acid product. Step 4: The concentrated sodium solution 2 is introduced into the membrane distillation separation device 2 to separate iron and zinc from hydrochloric acid, resulting in membrane distillation concentrate 2 and membrane distillation acid product 2. Both membrane distillation separation device 1 and membrane distillation separation device 2 are equipped with hydrophobic membranes. Step 5: Allow membrane distillation concentrate 1 to enter subsequent process 1, and allow membrane distillation concentrate 2 to enter subsequent process 2; In step one, the acidic waste liquid is pretreated using a pretreatment device. The pretreatment device includes a base, a sedimentation tank, and a pump body. The sedimentation tank and the pump body are both fixed to the base. The sedimentation tank has a cavity. A stirring assembly is connected to the inner wall of the cavity. A flocculant additive is fixed to the inner wall of the cavity. The flocculant additive is filled with flocculant. An inlet pipe and a transfer pipe are fixed to the sedimentation tank. The transfer pipe is fixed to the pump body. A grid is connected to the inner wall of the transfer pipe. The drive assembly includes gear one, sprocket one, chain, sprocket two, gear two, and servo motor one. Gear one is rotatably connected to the mounting plate, sprocket one is fixed to gear one, and a transmission cavity is provided on the sedimentation tank. The bottom wall of the cavity is connected to the bottom wall of the sedimentation tank through a waste discharge channel. Servo motor one is fixed to the inner wall of the transmission cavity, gear two is fixed to the output shaft of servo motor one, sprocket two is fixed to gear two, and sprocket two is connected to sprocket one through the chain. A toothed plate is slidably connected to the inner wall of the transmission cavity, and the toothed plate meshes with gear two. The toothed plate extends into the waste discharge channel. A collection net is slidably connected to the bottom wall of the cavity. Servo motor two is fixed to the sedimentation tank, and a threaded rod is rotatably connected to the inner wall of the cavity. The threaded rod is fixed to the output shaft of servo motor two. A threaded hole is provided on the collection net, and the threaded rod and the inner wall of the threaded hole are threadedly connected. An extension bar is fixedly connected to the second gear. A sliding plate and a striking rod are slidably connected to the inner wall of the transmission cavity. The sliding plate and the striking rod are fixedly connected. The sliding plate is connected to the inner wall of the transmission cavity through the second spring. A vibrating element is fixedly connected to the top wall of the transmission cavity. The top wall of the vibrating element extends to the bottom wall of the cavity. A roller is rotatably connected to the extension bar. One end of the striking rod is curved. The vibrating element is provided with a curved surface.

2. The pickling wastewater treatment method based on resource recovery according to claim 1, characterized in that, The nanofiltration membrane material includes one or more of polyamide, polysulfonamide, polysulfonamide-polyamine, polyamine, polyurea, and sulfonated polyether ether ketone.

3. The pickling wastewater treatment method based on resource recovery according to claim 1, characterized in that, The nanofiltration membrane is one of the following: positively charged, negatively charged, or Janus nanofiltration membrane.

4. The pickling wastewater treatment method based on resource recovery according to claim 1, characterized in that, The hydrophobic membrane is one of the following: a polysulfonamide acid-resistant nanofiltration membrane, a polyamine acid-resistant nanofiltration membrane, or a polytetrafluoroethylene hydrophobic membrane.

5. The pickling wastewater treatment method based on resource recovery according to claim 1, characterized in that, The first nanofiltration solution is heated to 53°C before entering the first membrane distillation separation device, and the second nanoconcentrated solution is heated to 53°C before entering the second membrane distillation separation device.

6. A method for treating pickling wastewater based on resource recovery according to any one of claims 1-5, characterized in that, Both the first and second subsequent processes include one or more of solvent extraction, electrolysis, precipitation, ion exchange resin, and ion exchange membrane, to further realize the recycling of metals.

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