Device and method for electrochemically treating chemical nickel plating waste liquid

Abstract

The invention discloses a device and a method for electrochemically treating chemical nickel plating waste liquid. The device comprises a pH regulating tank, an electrolytic tank, a reaction tank, a sedimentation tank and a clean water tank which are sequentially connected through pipelines, stirring devices are arranged in the pH adjusting tank and the reaction tank; an electrode mechanism and an air stirring coil pipe are arranged in the electrolytic tank, and the air stirring coil pipe is arranged below the electrode mechanism and is connected with the air compressor through a pipeline; the electrode mechanism is electrically connected with the direct-current power supply; an inclined tube filler is arranged in the sedimentation tank; a water flow control valve and a water pump are arranged on a pipeline between every two adjacent pool bodies; the method comprises the steps that under the action of a direct-current electric field, organic pollutants are removed through anode electrooxidation, nickel ions are recycled through cathode electroreduction deposition, and clear water reaching the standard is obtained after chemical treatment and precipitation separation. Under the electrolysis condition of 2-5 h, the nickel ion removal rate reaches 99.9%, the concentration is reduced to be smaller than 1 ppm, COD is remarkably reduced, and efficient purification and resource utilization of the chemical nickel plating waste liquid are achieved.

Description

Technical Field

[0001] This invention belongs to the field of chemical nickel plating wastewater treatment technology, specifically relating to an apparatus and method for electrochemically treating chemical nickel plating wastewater. Background Technology

[0002] Electroless nickel plating is widely used in electronics, machinery, precision manufacturing, and surface functionalization due to its dense deposits, excellent corrosion resistance, and the fact that it requires no external power source. However, its wastewater contains high concentrations of nickel ions and complexing agents and stabilizers such as hypophosphite, citrate, and lactate, exhibiting characteristics such as high COD (chemical oxygen demand), strong complexing properties, and recalcitrant degradation. Direct discharge without effective treatment not only poses serious threats to the ecological environment and human health but also leads to a significant loss of nickel resources. Therefore, achieving deep purification and resource recovery of electroless nickel plating wastewater has become an urgent technical challenge.

[0003] Existing treatment methods include chemical precipitation, Fenton oxidation, adsorption, membrane separation, and biological methods. Chemical precipitation is a mature process, but it requires large amounts of reagents and generates secondary sludge, and it is difficult to remove COD. The Fenton process can degrade some organic matter, but it produces large amounts of iron sludge and cannot recover nickel. Adsorption has limited removal capacity, and adsorbent regeneration is difficult. Membrane separation can retain metal ions, but it suffers from membrane fouling and high operating costs. Biological methods have low treatment efficiency due to the inhibitory effect of complexing agents. Existing patents, such as CN119219258A, improve efficiency through multi-stage membrane integration, but metal recovery is difficult and still constrained by membrane fouling. CN111573883A uses iron-based catalysts to break the complex and improve recovery rates, but it involves multiple types of reagents and is complex to operate.

[0004] In summary, current technologies struggle to simultaneously achieve efficient removal of organic pollutants and resource recovery of nickel ions from electroless nickel plating wastewater. Furthermore, traditional equipment is generally bulky and lacks integration, hindering system upgrades for electroplating companies. Therefore, there is an urgent need to develop a green, low-consumption electrochemical treatment technology and device that combines purification and recovery functions. Summary of the Invention

[0005] This invention addresses the challenges posed by high nickel concentration, high COD, and unstable complexing agents in existing technologies. Its purpose is to provide an apparatus and method for electrochemically treating electroless nickel plating wastewater.

[0006] This invention is achieved through the following technical solution:

[0007] An apparatus for electrochemically treating electroless nickel plating waste liquid includes a pH adjustment tank, an electrolytic tank, a reaction tank, a sedimentation tank, and a clear water tank connected in sequence by pipelines; a stirring device is installed in the pH adjustment tank and the reaction tank; an electrode mechanism and an air stirring coil are installed in the electrolytic tank, the air stirring coil being located below the electrode mechanism and connected to an air compressor via pipelines; the electrode mechanism is electrically connected to a DC power supply; inclined tube packing is installed in the sedimentation tank; and water flow control valves and water pumps are installed on the pipelines between adjacent tanks.

[0008] The above technical solution also includes a backup pool connected to the clear water pool via a pipeline.

[0009] In the above technical solution, the pH adjustment tank, electrolysis tank, reaction tank, sedimentation tank, clear water tank and spare tank are all set on a stainless steel frame.

[0010] In the above technical solution, the bottom of the pH adjustment tank, electrolysis tank, reaction tank, sedimentation tank, clear water tank and spare tank are all equipped with residual water venting valves.

[0011] In the above technical solution, the electrode mechanism includes an acrylic electrode support and an electrode assembly disposed within the acrylic electrode support. The electrode assembly consists of multiple anode plates and multiple cathode plates. The inner wall of the acrylic electrode support forms a slot, into which the anode plates and cathode plates are inserted.

[0012] In the above technical solution, the anode plate and cathode plate are staggered and parallel to each other; the anode plate and cathode plate are respectively fixed to the acrylic electrode support by the anode electrode clamp and the cathode electrode clamp, and are respectively connected to the positive and negative terminals of the DC power supply through the anode copper busbar and the cathode copper busbar to form an electrolysis circuit; the anode electrode clamp and the anode plate, and the cathode electrode clamp and the cathode plate are all fixedly connected by the plate clamp locking nut.

[0013] In the above technical solution, the air stirring coil is set at the bottom of the electrolytic cell, and multiple ventilation micropores are evenly distributed on the side of the coil near the electrode mechanism.

[0014] In the above technical solution, the device for electrochemically treating electroless nickel plating waste liquid also includes a control cabinet, which is electrically connected to a DC power supply, various water pumps, an air compressor, and a stirring device.

[0015] A method for treating electroless nickel plating waste liquid using an electrochemical apparatus includes the following steps: introducing the electroless nickel plating waste liquid into a pH adjustment tank, and adjusting it to a suitable pH after stirring and homogenization; pumping it into an electrolytic cell, where, under the action of a DC power supply, the anode undergoes an electro-oxidation reaction to remove organic pollutants, and the cathode undergoes an electro-reduction reaction to recover nickel ions, while simultaneously introducing microbubbles of air into the bottom of the tank to enhance mass transfer; the electrolyzed waste liquid enters a reaction tank, where a neutralizing agent, flocculant, or adsorbent is added and stirred; the mixture enters a sedimentation tank, where solid-liquid separation is achieved using inclined tube packing, the precipitated sludge is discharged, and the supernatant flows into a clear water tank for storage.

[0016] In the above technical solution, the pH of the conditioning tank is 3-6; the nickel ion concentration in the electroless nickel plating waste liquid is 500-8000 ppm, and the chemical oxygen demand is 10000-70000 ppm; the maximum current of the electrolytic cell is 103 A, and the current density is 30-80 mA / cm². 2 The electrolysis time is 2-5 hours.

[0017] The beneficial effects of this invention are:

[0018] This invention provides an apparatus and method for electrochemically treating electroless nickel plating wastewater. It achieves deep removal of organic pollutants from the wastewater through anodic electro-oxidation and efficient recovery of nickel ions through cathodic electro-reduction. Combined with aeration-enhanced mass transfer and subsequent precipitation separation processes, it can recover nickel resources while purifying the wastewater, thus achieving both environmental and economic benefits. This invention, through the coupled design of electrolytic mineralization, recovery, air-enhanced mass transfer, and flocculation sedimentation, effectively improves pollutant removal and resource recovery rates, reduces reagent consumption, solves the industry's environmental pollution problems, promotes human health, and has promising application prospects. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the electrode mechanism in this invention;

[0021] Figure 3 This is an exploded structural diagram of the electrode assembly in this invention;

[0022] Figure 4 This is a schematic diagram of the front piece of the anode electrode clamp / cathode electrode clamp in this invention;

[0023] Figure 5 This is a schematic diagram of the structure of the rear piece of the anode electrode clamp / cathode electrode clamp in this invention;

[0024] Figure 6 This is a schematic diagram of the structure of the anode copper busbar / cathode copper busbar in this invention;

[0025] Figure 7 This is a top view of the air stirring coil in this invention;

[0026] Figure 8 This is a photograph of the metal deposits recovered on the cathode plate during the electrolysis process in Embodiment 1 of the present invention;

[0027] Figure 9 This is the XRD pattern of the electrolytic deposition product in Example 1 of the present invention.

[0028] in:

[0029] 1. pH adjustment tank; 2. Electrolytic cell; 3. Reaction tank; 4. Sedimentation tank; 5. Clear water tank; 6. Backup tank; 7. Stainless steel frame; 8. Anode plate; 9. Cathode plate; 10. DC power supply; 11. Air stirring coil; 12. Air compressor; 13. First pipeline; 14. First water flow control valve; 15. First water pump; 16. Second pipeline; 17. Second water flow control valve; 18. Second water pump; 19. Third pipeline; 20. Third water flow control valve; 21. Third water pump; 22. Fourth pipeline; 23. Fourth water flow control valve 24. Fourth water pump; 25. Fifth pipeline; 26. Fifth water flow control valve; 27. Fifth water pump; 28. Residual water vent valve for regulating tank; 29. ​​Residual water vent valve for electrolytic cell; 30. Residual water vent valve for reaction tank; 31. Sewage discharge valve for sedimentation tank; 32. Residual water vent valve for clear water tank; 33. Residual water vent valve for standby tank; 34. Inclined tube packing; 35. Control cabinet; 36. Acrylic electrode bracket; 37. Anode copper busbar; 38. Anode electrode clamp; 39. Electrode clamp locking nut; 40. Cathode electrode clamp; 41. Cathode copper busbar.

[0030] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] like Figures 1-7 As shown, an apparatus for electrochemically treating electroless nickel plating waste liquid includes a pH adjustment tank 1, an electrolytic tank 2, a reaction tank 3, a sedimentation tank 4, a clear water tank 5, and a standby tank 6 connected in sequence by pipelines.

[0033] The pH adjustment tank 1 and the reaction tank 3 are equipped with stirring devices to achieve waste liquid homogenization and reagent mixing reaction;

[0034] The electrolytic cell 2 is equipped with an electrode mechanism and an air stirring coil 11. The air stirring coil 11 is located below the electrode mechanism and is connected to the air compressor 12 via a pipeline. The electrode mechanism is electrically connected to the DC power supply 10. The sedimentation tank 4 is equipped with inclined tube packing 34 to enhance the solid-liquid separation process. The clear water tank 5 and the spare tank 6 are used to collect the treated effluent.

[0035] Water flow control valves and water pumps are installed on the pipelines between adjacent tanks to regulate the inflow and outflow of water and the delivery pressure between different tanks. Specifically: the bottom outlet of pH adjustment tank 1 and the upper inlet of electrolysis tank 2 are connected by a first pipeline 13, and a first water flow control valve 14 and a first water pump 15 are installed on the first pipeline 13; the bottom outlet of electrolysis tank 2 and the upper inlet of reaction tank 3 are connected by a second pipeline 16, and a second water flow control valve 17 and a second water pump 18 are installed on the second pipeline 16; the bottom of reaction tank 3... The outlet and the upper inlet of the sedimentation tank 4 are connected by a third pipe 19, and a third water flow control valve 20 and a third water pump 21 are installed on the third pipe 19; the upper clarified liquid outlet of the sedimentation tank 4 and the upper inlet of the clear water tank 5 are connected by a fourth pipe 22, and a fourth water flow control valve 23 and a fourth water pump 24 are installed on the fourth pipe 22; the bottom outlet of the clear water tank 5 and the upper inlet of the spare tank 6 are connected by a fifth pipe 25, and a fifth water flow control valve 26 and a fifth water pump 27 are installed on the fifth pipe 25.

[0036] The pH adjustment tank 1, electrolysis tank 2, reaction tank 3, sedimentation tank 4, clear water tank 5 and spare tank 6 are all set on the stainless steel frame 7. Specifically, the pH adjustment tank 1, electrolysis tank 2, reaction tank 3, sedimentation tank 4, clear water tank 5 and spare tank 6 are set on the upper layer of the stainless steel frame 7, and the remaining water pumps, valves and air compressor 12 are set on the lower layer of the stainless steel frame 7.

[0037] The bottom of each of the pH adjustment tank 1, electrolysis tank 2, reaction tank 3, sedimentation tank 4, clear water tank 5, and standby tank 6 is equipped with a residual water vent valve for draining and cleaning after operation. Specifically: pH adjustment tank 1 is equipped with a residual water vent valve 28; electrolysis tank 2 is equipped with a residual water vent valve 29; reaction tank 3 is equipped with a residual water vent valve 30; sedimentation tank 4 is equipped with a sedimentation tank drain valve 31 for periodic discharge of deposited sludge; clear water tank 5 is equipped with a clear water tank residual water vent valve 32; and standby tank 6 is equipped with a standby tank residual water vent valve 33.

[0038] The electrode mechanism includes an acrylic electrode support 36 and multiple anode plates 8 and multiple cathode plates 9 disposed within the acrylic electrode support 36; the inner wall of the acrylic electrode support 36 forms a slot, and the anode plates 8 and cathode plates 9 are inserted into the slot to form a detachable structure, so as to facilitate electrode replacement and heavy metal recovery.

[0039] The anode plate 8 and cathode plate 9 are staggered and parallel to each other. The anode plate and cathode plate are fixed to the acrylic electrode support 36 by the anode electrode clamp 38 and the cathode electrode clamp 40, respectively, and are connected to the positive and negative terminals of the DC power supply 10 through the anode copper busbar 37 and the cathode copper busbar 41, respectively, to form an electrolysis circuit. The anode electrode clamp 38 and the anode plate, and the cathode electrode clamp 40 and the cathode plate are all fixedly connected by the plate clamp locking nut.

[0040] The anode electrode clamp 38 is fastened to the anode copper busbar 37 by screws, and the cathode electrode clamp 40 is fastened to the cathode copper busbar 41 by screws. A nickel-plated copper conductive pad is provided on the contact surface to reduce the contact resistance.

[0041] The anode copper busbar 37 and the cathode copper busbar 41 are made of high-conductivity copper plates with rectangular cross sections. One end of the copper busbar is reliably fixed to the electrode clamp, and the other end is connected to the positive and negative leads of the DC power supply by bolts.

[0042] The anode electrode clamp 38 and the cathode electrode clamp 40 have the same structure, both consisting of a front piece and a rear piece, which are connected by screws, and the anode plate 8 or cathode plate 9 is clamped between the front piece and the rear piece; the front piece is rectangular with multiple connecting holes; the rear piece is L-shaped with an extension piece at the top, and connecting holes corresponding to the front position are formed on the rear piece, and connecting holes for connecting to the copper busbar are formed on the connecting piece;

[0043] The anode plate 8 is made of boron-doped diamond; the cathode plate 9 is made of titanium; the electrode area of ​​the anode plate 8 and the cathode plate 9 is 200 cm². 2 ~500cm 2 .

[0044] The air stirring coil 11 is disposed at the bottom of the electrolytic cell 2, and multiple ventilation micro-holes are evenly distributed on the side near the electrode mechanism. After the air stirring coil 11 is connected to the air compressor 12 through a pipeline, gas overflows from each ventilation micro-hole. The ventilation micro-holes blow air micro-bubbles to enhance the stirring and mass transfer effect of the pool liquid. The air stirring coil 11 is any one of the following: serpentine coil, spiral coil, tic-tac-toe coil, or grid-shaped coil.

[0045] The pH adjustment tank 1, electrolysis tank 2, reaction tank 3, sedimentation tank 4, clear water tank 5, and spare tank 6 are all made of polypropylene, which is corrosion resistant.

[0046] The device for electrochemically treating electroless nickel plating waste liquid also includes a control cabinet 35, which is electrically connected to a DC power supply 10, various water pumps, an air compressor 12, and a stirring device, and is used to realize centralized automated control of the electrolytic power supply, water pumps, stirring, and aeration during the waste liquid treatment process.

[0047] Example 2

[0048] A method for treating electroless nickel plating wastewater using the apparatus described in Example 1 includes the following steps:

[0049] (I) Introduce the chemical nickel plating waste liquid into a pH adjustment tank, and adjust it to a suitable pH after stirring and homogenization;

[0050] (II) The water is pumped to the electrolytic cell and electrolytic reaction is carried out under the action of DC power. The anode undergoes an electro-oxidation reaction to remove organic pollutants, and the cathode undergoes an electro-reduction reaction. Metal ions are deposited on the surface of the cathode plate to recover nickel ions. At the same time, air microbubbles are blown into the bottom of the electrolytic cell by an air compressor to enhance mass transfer.

[0051] (III) The waste liquid after electrolysis is pumped to the reaction tank, where neutralizing agent, flocculant or adsorbent is added and stirred.

[0052] (IV) The mixed waste liquid enters the sedimentation tank, where solid-liquid separation is achieved by using inclined tube packing. The deposited sludge is discharged through the sludge discharge port, and the supernatant flows into the clear water tank. After testing, it is transported to the spare tank for storage or reuse.

[0053] The pH of the conditioning tank is 3 to 6.

[0054] The nickel ion concentration in the electroless nickel plating waste liquid is 500-8000 ppm, and the chemical oxygen demand is 10000-70000 ppm.

[0055] The maximum current for the electrolysis reaction is 10³ A, and the current density is 30-80 mA / cm². 2 The electrolysis time is 2 to 5 hours.

[0056] The added agent is a neutralizing agent (calcium oxide), a flocculant (polyacrylamide), or an adsorbent (hydrotalcite).

[0057] Application Example 1

[0058] Each tank is made of corrosion-resistant polypropylene. The anode plates are made of boron-doped diamond electrodes, and the cathode plates are made of titanium electrodes. The electrode module consists of 7 cathodes and 6 anodes connected in series. Each electrode plate is 3mm thick and has an area of ​​312cm². 2 .

[0059] Adopting such Figure 1 The electroplating waste liquid treatment device adopts, for example Figure 2 Electrolysis of the electrode assembly, and by Figure 4 The electrode clamps are fixed at / 5, and the electrode is connected to a DC power supply via a copper busbar. Chemical nickel plating wastewater with a nickel content of 853.7 ppm is introduced into a regulating tank for water quality homogenization, and then pumped to the electrolytic cell for electrolytic reaction under DC power. Figure 7 Air agitation was used to enhance mass transfer, and continuous electrolysis was performed at a constant current of 37.6A. After 3 hours of electrolysis, nickel ions were deposited and recovered on the cathode plate, while an electro-oxidation reaction was carried out on the anode plate to remove organic pollutants. Detailed information on the electrolytic treatment of electroless nickel plating wastewater is shown in Table 1. After 3 hours of continuous electrolysis, the nickel ion concentration decreased to 0.87 ppm, achieving a removal rate of 99.9%.

[0060] Table 1: Electrolytic Treatment of Chemical Nickel Plating Wastewater

[0061]

[0062] The waste liquid after electrolysis enters the reaction tank, where reagents are added and the mixture is stirred before entering the sedimentation tank. Under the action of inclined tube packing, rapid solid-liquid separation is achieved. The settled sludge is discharged through the drain valve, and the supernatant enters the clear water tank. After passing the test, it is transported to the standby tank for storage.

[0063] Figure 8 This is a photograph of the recovered nickel product on the cathode plate in Example 1. Figure 9 The X-ray diffraction pattern confirmed that the recovered product on the cathode plate in Example 1 was nickel.

[0064] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0065] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and 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, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0066] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0067] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An apparatus for electrochemically treating electroless nickel plating waste liquid, characterized in that: The system includes a pH adjustment tank (1), an electrolysis tank (2), a reaction tank (3), a sedimentation tank (4), and a clear water tank (5) connected in sequence by pipelines. Stirring devices are installed in the pH adjustment tank (1) and the reaction tank (3). An electrode mechanism and an air stirring coil (11) are installed in the electrolysis tank (2). The air stirring coil (11) is located below the electrode mechanism and is connected to an air compressor (12) through a pipeline. The electrode mechanism is electrically connected to a DC power supply (10). Inclined tube packing (34) is installed in the sedimentation tank (4). Water flow control valves and water pumps are installed on the pipelines between adjacent tanks.

2. The apparatus for electrochemically treating electroless nickel plating waste liquid according to claim 1, characterized in that: It also includes a spare pool (6) connected to the clear water pool (5) via a pipeline.

3. The apparatus for electrochemically treating electroless nickel plating waste liquid according to claim 2, characterized in that: The pH adjustment tank (1), electrolysis tank (2), reaction tank (3), sedimentation tank (4), clear water tank (5) and spare tank (6) are all mounted on a stainless steel frame (7).

4. The apparatus for electrochemically treating electroless nickel plating waste liquid according to claim 2, characterized in that: The bottom of the pH adjustment tank (1), electrolysis tank (2), reaction tank (3), sedimentation tank (4), clear water tank (5) and spare tank (6) are all equipped with residual water venting valves.

5. The apparatus for electrochemically treating electroless nickel plating waste liquid according to claim 1, characterized in that: The electrode mechanism includes an acrylic electrode support (36) and an electrode assembly disposed within the acrylic electrode support (36). The electrode assembly consists of multiple anode plates (8) and multiple cathode plates (9). The inner wall of the acrylic electrode support (36) forms a slot, into which the anode plates (8) and cathode plates (9) are inserted.

6. The apparatus for electrochemically treating electroless nickel plating waste liquid according to claim 5, characterized in that: The anode plate (8) and cathode plate (9) are staggered and parallel to each other. The anode plate and cathode plate are fixed to the acrylic electrode bracket (36) by the anode electrode clamp (38) and cathode electrode clamp (40) respectively, and are connected to the positive and negative terminals of the DC power supply (10) through the anode copper busbar (37) and cathode copper busbar (41) respectively, forming an electrolysis circuit. The anode electrode clamp (38) and the anode plate, and the cathode electrode clamp (40) and the cathode plate are all fixedly connected by the plate clamp locking nut.

7. The apparatus for electrochemically treating electroless nickel plating waste liquid according to claim 1, characterized in that: The air stirring coil (11) is located at the bottom of the electrolytic cell (2), and multiple ventilation micropores are evenly distributed on the side of it closest to the electrode mechanism.

8. The apparatus for electrochemically treating electroless nickel plating waste liquid according to claim 1, characterized in that: The device for electrochemically treating electroless nickel plating waste liquid also includes a control cabinet (35), which is electrically connected to a DC power supply (10), various water pumps, an air compressor (12), and a stirring device.

9. A method for treating electrochemical nickel plating waste liquid using the apparatus according to any one of claims 1 to 8, characterized in that: Includes the following steps: The chemical nickel plating waste liquid is introduced into a pH adjustment tank, and after stirring and homogenization, it is adjusted to a suitable pH. The solution is pumped into an electrolytic cell. Under the action of a DC power supply, the anode undergoes an electro-oxidation reaction to remove organic pollutants, while the cathode undergoes an electro-reduction reaction to recover nickel ions. At the same time, air microbubbles are bubbled into the bottom of the cell to enhance mass transfer. The waste liquid after electrolysis enters a reaction tank, where neutralizing agents, flocculants, or adsorbents are added and stirred. The mixture enters a sedimentation tank, where solid-liquid separation is achieved using inclined tube packing. The settled sludge is discharged, and the supernatant flows into a clear water tank for storage.

10. The method for electrochemically treating electroless nickel plating waste liquid according to claim 1, characterized in that: The pH of the conditioning tank is 3-6; the nickel ion concentration in the electroless nickel plating waste liquid is 500-8000 ppm, and the chemical oxygen demand is 10000-70000 ppm; the maximum current of the electrolytic cell is 103 A, and the current density is 30-80 mA / cm². 2 The electrolysis time is 2-5 hours.

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