Electroplating wastewater treatment system

Abstract

The invention relates to the field of wastewater treatment, and discloses an electroplating wastewater treatment system which comprises a physical pretreatment module, a dynamic pulse acoustoelectric reaction module, a resource recovery and electrode regeneration module and a central process control module, wherein in the dynamic pulse acoustoelectric reaction module, through the synergistic effect of a sound field constructed by an ultrasonic transducer and a pulse electric field constructed by a programmable pulse power supply, stable metal complexes in the wastewater are broken through acoustochemistry, and released metal ions are reduced and deposited on a three-dimensional porous working electrode through electrochemistry. The central process control module is used for periodically switching between a main reaction stage and an electrode activation stage, in the electrode activation stage, the polarity of the electrode is reversed, the working electrode serves as an anode, organic and inorganic passivation layers accumulated on the surface of the working electrode are removed in situ, the electrochemical activity of the working electrode is recovered, high-purity metal is recycled in an electrolytic stripping mode, and the high-purity metal is recycled. And regeneration and reuse of the electrode substrate are realized.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an electroplating wastewater treatment system. Background Technology

[0002] Electroplating is a fundamental part of modern manufacturing, but its production process generates wastewater containing high concentrations of heavy metal ions. These heavy metals, such as copper, nickel, gold, and chromium, pose a serious threat to the ecological environment and human health if discharged directly without treatment. Therefore, the effective treatment of electroplating wastewater is a key issue in the field of environmental protection.

[0003] In electroplating wastewater, heavy metal ions often form highly stable water-soluble metal complexes with complexing agents (such as ethylenediaminetetraacetic acid (EDTA) and cyanide) added to the electroplating solution. The presence of these complexes poses a significant challenge to traditional treatment methods. For example, chemical precipitation, one of the most commonly used techniques, works by adding alkali to raise the pH of the wastewater, causing metal ions to precipitate as hydroxides. However, once metal ions are chelated by strong complexing agents, their chemical properties become extremely stable, making it difficult to effectively dissociate them from the complexes using conventional pH adjustments. This results in low metal removal rates, and the treated effluent fails to meet increasingly stringent discharge standards. Furthermore, chemical precipitation generates large quantities of complex and hazardous chemical sludge, which incurs high transportation and disposal costs and poses a risk of secondary pollution.

[0004] To overcome the challenge of stabilizing complexes, academia and industry have begun exploring electrochemical methods. Theoretically, electrochemical methods can directly deposit and recover elemental metals from metal ions through the reduction action of the cathode, demonstrating potential for resource recovery. However, in treating complex electroplating wastewater, this method has revealed its inherent technical bottleneck over long-term operation: electrode passivation. During electrolysis, in addition to the deposition of the target metal on the cathode surface, the local increase in pH at the interface also leads to the precipitation of metal hydroxides. More seriously, the organic functional groups of the complexing agent or their degradation fragments easily adsorb onto the active sites of the electrode. The gradual accumulation of these inorganic precipitates and organic pollutants forms a dense passivation layer on the electrode surface. This passivation layer severely hinders electron transfer and mass transfer, resulting in a sharp decline in current efficiency, significantly reduced treatment effectiveness, and ultimately, even the interruption of the entire electrochemical process. To restore the activity of the electrodes, existing processes typically require interrupting system operation, removing the passivated electrodes, and performing tedious offline regeneration processes such as acid washing, alkali washing, or mechanical polishing. This not only significantly increases the complexity of operation and maintenance costs, but also fails to meet the requirements of industrial production for the continuity and stability of the processing flow.

[0005] Therefore, there is an urgent need for a new electroplating wastewater treatment technology that can efficiently break down stable metal complexes, effectively solve the passivation and deactivation problem during online electrode operation, and also take into account the resource recovery of valuable metals. Summary of the Invention

[0006] The purpose of this invention is to provide an electroplating wastewater treatment system that solves the problems of low treatment efficiency of stable complexed wastewater, easy passivation of electrodes, and difficulty in resource recovery.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an electroplating wastewater treatment system, comprising: A reactor is the physical space for a reaction. The working electrode and the counter electrode are disposed within the reactor; An ultrasonic transducer for generating an ultrasonic field within the reactor. An ion-selective membrane disposed between the working electrode and the counter electrode; A programmable pulse inversion power supply electrically connected to the working electrode and the counter electrode is used to provide a pulse current whose output polarity can be reversed within a preset period. A central process controller connected to the programmable pulse inversion power supply and the ultrasonic transducer signal.

[0008] Preferably, the central process controller is used to control the programmable pulse inversion power supply to cyclically execute a main reaction stage and an electrode activation stage in each preset cycle; in the main reaction stage, the working electrode serves as the cathode; in the electrode activation stage, the working electrode serves as the anode.

[0009] Preferably, in the main reaction stage, the ultrasonic transducer generates an ultrasonic field to trigger a sonochemical effect to break down the metal complexes in the wastewater, and at the same time, the working electrode, which serves as the cathode, electrolytically reduces and deposits the metal ions released by the metal complexes.

[0010] Preferably, during the electrode activation stage, the working electrode, which serves as the anode, is used to achieve electrochemical oxidative stripping of organic pollutants adsorbed on its surface, as well as acidic dissolution of the formed metal hydroxides.

[0011] Preferably, the central process controller is also used to adjust the duration of the main reaction stage and the electrode activation stage, the current density output by the programmable pulse inversion power supply, and the ultrasonic power output by the ultrasonic transducer according to a preset algorithm or feedback signals from the sensor. The sensors include differential pressure sensors installed at both ends of the physical pretreatment module to monitor the degree of filter plate clogging; and monitoring sensors installed inside the dynamic pulse acoustic-electric reaction module to monitor the pH value, oxidation-reduction potential (ORP), and conductivity of the wastewater. The preset algorithm is used to realize on-demand triggering and closed-loop control of the electrode activation stage based on the feedback signal characterizing the real-time surface state of the working electrode, and to dynamically optimize the current density and ultrasonic power during the main reaction stage based on the feedback signal characterizing the real-time efficiency of the metal deposition process.

[0012] Preferably, the working electrode is a three-dimensional porous electrode.

[0013] Preferably, the ion-selective membrane is a cation-selective membrane.

[0014] Preferably, the system further includes a physical pretreatment module for removing suspended solids from the wastewater, located upstream of the reactor inlet.

[0015] Preferably, the physical pretreatment module includes multiple detachably connected filter boxes, each filter box containing a filter plate that can move between a filtration area and a backup area, and a sewage discharge mechanism that is linked to the movement of the filter plate.

[0016] Preferably, the system further includes a resource recovery and electrode regeneration module, which includes an acidic electrolytic stripping tank for electrolyzing the metal-rich working electrode as an anode to strip the metal.

[0017] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention achieves the removal of metal complexes in wastewater and the simultaneous deposition and recovery of valuable metals in the same main reaction stage through the sonochemical effect generated by the ultrasonic transducer and the electrolytic reduction effect of the working electrode as the cathode. By utilizing this synergistic effect, the traditionally separate complex removal and recovery steps are coupled into a single process, simplifying the overall treatment process.

[0018] 2. This invention achieves online in-situ self-cleaning of the working electrode by setting a periodic electrode activation stage and using a programmable pulse reversal power supply to reverse the polarity of the working electrode. When the electrode is used as an anode, it can remove organic pollutants adsorbed on its surface through electrochemical oxidation. The local acidic environment generated by the anodic reaction dissolves any metal hydroxide precipitates that may be formed, effectively overcoming the electrode passivation problem and ensuring the long-term stable operation of the system.

[0019] 3. The system of the present invention decomposes organic pollutants in wastewater into inorganic small molecules, and at the same time recovers heavy metal ions directly to the working electrode in the form of elemental metals. The entire treatment process does not require the addition of any chemical precipitant, thus fundamentally avoiding the generation of hazardous chemical sludge. While realizing the resource recovery of wastewater, it also completes the harmless treatment of pollutants. Attached Figure Description

[0020] Figure 1 This is a system functional block diagram of the present invention; Figure 2 This is a functional diagram of the physical preprocessing module of the present invention; Figure 3 This is a schematic structural diagram of the dynamic pulse acoustic-electric reaction module of the present invention; Figure 4 This is a schematic structural diagram of the resource recovery and electrode regeneration module of the present invention; Figure 5 This is a functional block diagram of the central process control module of the present invention; Figure 6 This is a timing diagram of the system's working cycle according to the present invention; Figure 7 This is a flowchart illustrating the overall process flow of the present invention. Figure 8 This is a schematic diagram of the synergistic mechanism of the main reaction stage of the present invention; Figure 9 This is a schematic diagram of the electrode activation stage mechanism of the present invention. Detailed Implementation

[0021] The following is in conjunction with the appendix Figure 1 -Appendix Figure 9 The present invention will be further described in detail below.

[0022] This invention provides an electroplating wastewater treatment system, which includes, sequentially along the wastewater treatment path, a physical pretreatment module and a dynamic pulsed acoustic-electric reaction module. The system also includes a central process control module for overall system control, and a resource recovery and electrode regeneration module for treating metal-rich electrodes.

[0023] See attached document Figure 1 , Figure 1 This is a system functional block diagram of the present invention. The electroplating wastewater treatment system provided by the present invention is used to treat electroplating wastewater containing metal complexes.

[0024] The inlet of the physical pretreatment module is connected to an external wastewater source, and its outlet is in fluid communication with the inlet of the dynamic pulse acoustic-electric reaction module; the outlet of the dynamic pulse acoustic-electric reaction module discharges the treated water.

[0025] The central process control module establishes signal connections with the programmable pulse inversion power supply and ultrasonic transducer in the dynamic pulse acoustic-electric reaction module to output control commands. The programmable pulse inversion power supply is electrically connected to the working electrode and counter electrode in the dynamic pulse acoustic-electric reaction module to apply pulse current to them. The sensors installed in the dynamic pulse acoustic-electric reaction module are signal connected to the central process control module to provide it with real-time operating parameters. The central process control module is also signal connected to the physical pretreatment module and the resource recovery and electrode regeneration module to control their operation or initiate specific operations.

[0026] See attached document Figure 2 , Figure 2 This is a functional diagram of the physical preprocessing module of the present invention.

[0027] A physical pretreatment module is configured to remove suspended solids, floating oil, and other impurities from the electroplating wastewater entering the system. This module includes one or more filter boxes that can be connected in series. In embodiments including multiple filter boxes, each filter box is detachably connected via flanges and fasteners, and the pore size of its internal filter plates can decrease sequentially along the water flow direction to achieve staged filtration.

[0028] The internal space of each filter box is divided into a filtration area and a backup area. The filtration area is located on the main channel of wastewater, while the backup area is located on one side of the main channel and is isolated from it.

[0029] The filter box is equipped with a filter plate, which has filter holes for intercepting suspended solids. The filter plate can reciprocate linearly between the filter area and the backup area.

[0030] To enable the movement of the filter plate, a moving mechanism is provided on the filter box. In this embodiment, the moving mechanism includes a slider fixed to the edge of the filter plate, a drive motor disposed outside the filter box, and a lead screw transmission assembly that converts the rotational motion of the drive motor into the linear motion of the slider. The central process control module drives the filter plate to move on a preset track by sending control signals to the drive motor.

[0031] At the bottom of the filter box, corresponding to the backup area, is a drain mechanism. This drain mechanism includes a drain pipe and an electrically controlled valve controlled by a central process control module.

[0032] During normal filtration operation, the filter plate is located in the filtration area, and wastewater passes through its filter holes, while suspended solids are trapped on its water-facing surface. When the central process control module determines that the filter plate needs cleaning based on the differential pressure sensor signal or a preset time period, it will initiate a cleaning cycle.

[0033] In this cleaning cycle, the central process control module first controls the moving mechanism to transfer the filter plate carrying the trapped material from the filtration area to the backup area. Once the filter plate reaches the backup area, the central process control module immediately issues a command to open the electrically controlled valve of the drain mechanism. At this time, the dirt accumulated on the surface of the filter plate falls off the filter plate under the action of gravity or backwash fluid and is discharged through the drain pipe. After the drain is completed, the electrically controlled valve closes, and the moving mechanism then moves the clean filter plate back to the filtration area, restoring normal filtration operation. The movement of the filter plate and the opening / closing of the drain valve constitute a linked control system.

[0034] See attached document Figure 3 , Figure 3 This is a schematic diagram of the dynamic pulse acoustic-electric reaction module according to an embodiment of the present invention. This module is the core unit for performing the removal of metal complexes in electroplating wastewater, metal recovery, and electrode activation.

[0035] The dynamic pulsed acoustic-electric reaction module includes a reactor shell made of a corrosion-resistant material (such as polypropylene (PP), polyvinyl chloride (PVC), or stainless steel lined with polytetrafluoroethylene (PTFE). The shell has an inlet for connecting to a physical pretreatment module and an outlet for discharging treated water.

[0036] Inside the reactor shell, a working electrode and a counter electrode are arranged in parallel. In one specific embodiment, the working electrode employs a three-dimensional porous structure with a matrix material of graphite felt, carbon foam, or metal fiber felt. This three-dimensional porous structure provides a large specific surface area for the mass transfer and deposition of metal ions. The working electrode is designed as a modular structure that can be quickly disassembled and reassembled for easy removal from the reactor for subsequent processing. The counter electrode employs a size-stabilized anode (DSA), such as an iridium-tantalum coated titanium anode, which exhibits a high oxygen evolution overpotential and good electrocatalytic stability at the anodic potential.

[0037] Multiple ultrasonic transducers are arranged in an array on the outside of the reactor shell. These transducers are bonded to the outer wall of the reactor shell using acoustic coupling agent and are connected to the central process control module. This arrangement aims to project a uniform, high-intensity ultrasonic field into the wastewater inside the reactor. The frequency and output power of the ultrasonic waves are adjusted by the central process control module according to the treatment requirements.

[0038] An ion-selective membrane is disposed between the working electrode and the counter electrode. In this embodiment, the ion-selective membrane is a cation-selective membrane. This membrane is fixed to a frame inside the reactor shell by a sealing gasket, dividing the reactor interior into a working electrode region and a counter electrode region. The working electrode is located in the working electrode region, and the counter electrode is located in the counter electrode region. The characteristic of this cation-selective membrane is that it allows positively charged metal cations to pass through while blocking negatively charged anions and most neutral organic molecules, ensuring the purity of the metal deposition process within the working electrode region.

[0039] A programmable pulse inverting power supply has its positive and negative output terminals electrically connected to the working electrode and the counter electrode, respectively, via wires. This power supply receives commands from a central process control module and can provide pulsed currents whose polarity, current density, duty cycle, and frequency can all be periodically varied according to a preset program. By controlling the output of this power supply, the periodic reversal of the polarity of the working electrode and the counter electrode can be achieved.

[0040] See attached document Figure 4 , Figure 4 This is a schematic diagram of the structure of a resource recovery and electrode regeneration module according to an embodiment of the present invention.

[0041] This module is used to perform offline metal stripping and recovery and electrode substrate regeneration on working electrodes that have been enriched with target metals in the dynamic pulsed acoustic-electric reaction module.

[0042] The resource recovery and electrode regeneration module includes an acidic electrolytic stripping tank. The tank is made of acid-resistant material (such as fiberglass or steel plate lined with acid-resistant rubber) and contains an acidic electrolyte, such as a sulfuric acid or nitric acid solution of a specific concentration.

[0043] An electrode clamp is installed inside the acidic electrolytic stripping tank. This electrode clamp includes an anode connection end and a cathode connection end, configured to fix a metal-rich working electrode, taken from the dynamic pulsed acoustic-electrochemical reaction module, as the anode, and simultaneously fix one or more cathode plates as the cathodes. A preset electrode spacing is maintained between the anode and cathode.

[0044] In this embodiment, the cathode plate is a stainless steel plate or a pure metal plate (e.g., a pure copper plate), used as a substrate for metal deposition.

[0045] The positive output terminal of a DC power supply is electrically connected to the anode connection terminal of the electrode clamp, and its negative output terminal is electrically connected to the cathode connection terminal. This DC power supply is used to apply a constant DC electric field to the anode and cathode within the acidic electrolytic stripping tank.

[0046] During resource recovery operations, the metal-rich working electrode is installed as the anode. Under the influence of a DC electric field, the metal deposited within its three-dimensional porous structure undergoes electrochemical dissolution and re-enters the acidic electrolyte as metal ions. Subsequently, these metal ions migrate to the surface of the cathode plate under the drive of the electric field and undergo a reduction reaction, depositing a high-purity metal layer on the cathode plate.

[0047] After the stripping process is complete, the clean working electrode substrate, now free of metal, is removed from the acidic electrolytic stripping tank. After cleaning and drying, it can be reinstalled in the dynamic pulse acoustic-electric reaction module for reuse. Simultaneously, the cathode plate with attached high-purity metal is also removed, and the metal layer on it can be stripped using physical or chemical methods to obtain the final metal product.

[0048] See attached document Figure 5 , Figure 5 This is a functional block diagram of the central process control module of the present invention. The central process control module is the control unit of the electroplating wastewater treatment system described in this invention, and is responsible for coordinating the automated operation of all other modules in the system.

[0049] In this embodiment, the hardware core of the central process control module is a programmable logic controller (PLC) or a distributed control system (DCS). The module also includes an input / output (I / O) interface connected to the PLC or DCS, a human-machine interface (HMI) for parameter setting and status monitoring, and a memory storing preset control programs.

[0050] The central process control module establishes signal connections with multiple sensors deployed in the system through its input interface to receive real-time process parameters. These sensors include: differential pressure sensors installed at both ends of the physical pretreatment module to monitor the degree of filter plate clogging; and monitoring sensors installed inside the dynamic pulse acoustic-electric reaction module to monitor the pH value, oxidation-reduction potential (ORP), and conductivity of the wastewater.

[0051] The central process control module sends control commands to various actuators in the system through its output interface. These actuators include: a programmable pulse inversion power supply and an ultrasonic transducer in the dynamic pulse acoustic-electric reaction module; a moving mechanism for driving the filter plate and a draining mechanism for controlling the discharge in the physical pretreatment module; and various pumps and electrically controlled valves in the system for conveying fluids.

[0052] The central process control module's memory contains preset control logic. This control logic is configured to periodically control the programmable pulse inversion power supply and the ultrasonic transducer to work together to cyclically execute the main reaction stage and the electrode activation stage. The control logic also includes a sensor feedback-based adjustment algorithm. The specific adjustment process of this algorithm is as follows: dynamic optimization control of the main reaction stage. Before the main reaction phase begins, feedforward control is performed based on the initial concentration of pollutants in the influent (this data can be input from upstream sensors or preset by the operator in the human-machine interface (HMI)) to set an initial reference value for the current density and ultrasonic power.

[0053] During the reaction, the algorithm continuously monitors the potential or electrochemical impedance of the working electrode. When a significant negative shift in potential or a stable impedance is detected, it indicates that the metal deposition process is proceeding smoothly. If the potential shift stagnates or the impedance begins to rise, the algorithm determines that mass transfer may be limited or initial passivation may have occurred. It will automatically and appropriately reduce the pulse current density and increase the ultrasonic power to enhance mass transfer and restore the deposition rate, thereby maintaining optimal current efficiency and deposition quality throughout the main reaction phase.

[0054] Precise triggering and closed-loop control of the electrode activation stage This regulation algorithm does not rely solely on a fixed time period to initiate electrode activation. Its primary triggering basis is the real-time diagnosis of the working electrode's health status. The algorithm sets a passivation threshold for electrochemical impedance. When the impedance of the working electrode exceeds this threshold during the main reaction phase, it indicates that the electrode surface is covered by contaminants or byproducts, resulting in a significant decrease in activity. At this point, the control module will immediately force the termination of the main reaction phase and automatically trigger the electrode activation phase.

[0055] During the electrode activation phase, the algorithm executes closed-loop control. It continuously applies a reverse pulse current while simultaneously monitoring the electrode's electrochemical impedance. The activation process continues until the electrode impedance returns to below a preset cleanliness baseline value. At this point, the algorithm determines that the electrode has regained activity and immediately stops activation. This method ensures that activation occurs on demand.

[0056] Auxiliary adjustment and safety monitoring of overall operating conditions Throughout the entire operating cycle, the algorithm uses the real-time monitored pH value as a key global monitoring indicator. For example, during the electrode activation phase, the anodic reaction produces acid, causing the pH to drop. The algorithm compares the pH value to a preset safe range (e.g., pH 2.0-3.0). When the actual pH value falls below the lower limit of the range, it indicates that the local acidity is too strong, which may corrode the electrode substrate. At this time, the algorithm automatically and temporarily reduces the current density of the reverse pulse or shortens the pulse on-time to slow down the acid production rate and allow the pH value to rise back to the safe range. This not only ensures the activation effect but also greatly extends the lifespan of the electrode.

[0057] Operators can select different wastewater treatments through the human-machine interface (HMI), and the system will automatically load the corresponding control parameters (such as passivation threshold, clean baseline, pH safety range, etc.). These core parameters can be fine-tuned, and real-time data curves and equipment status alarm information can be viewed, achieving a high degree of automation and flexibility.

[0058] In a specific operating mode, the control logic is also configured to achieve fully automatic cleaning based on the differential pressure sensor signal in the physical pretreatment module. When the differential pressure sensor detects that the pressure difference across the filter plate exceeds the preset clogging threshold, the central process control module will automatically execute a cleaning subroutine: suspend water supply to the dynamic pulse acoustic-electric reaction module, and sequentially trigger the moving mechanism and the sewage discharge mechanism to complete the movement, sewage discharge, and reset of the filter plate, before resuming normal water supply.

[0059] Reference Appendix Figure 7 Under the control of the central process control module, the system described in this invention operates in a preset working cycle within the dynamic pulse acoustic-electric reaction module to achieve continuous treatment of wastewater.

[0060] Reference Appendix Figure 6 In this embodiment, each working cycle is divided into a main reaction stage, an electrode activation stage, and a system rebalancing stage. These three stages are executed sequentially by the central process control module according to a preset program and time sequence, forming a complete processing loop.

[0061] The main reaction stage is the core stage for the removal of metal complexes and the electrolytic deposition of metals in the wastewater. At the start of this stage, the central process control module issues a command to configure the output of the programmable pulse inversion power supply to a forward pulse mode, making the working electrode the cathode and the counter electrode the anode. Simultaneously, the central process control module activates the ultrasonic transducer, generating an ultrasonic field with a preset power within the reactor. The duration of this stage is set by the central process control module based on the initial concentration of pollutants in the wastewater or a preset treatment target.

[0062] The electrode activation stage is used to restore the surface activity of the working electrode in situ online. After the main reaction stage, the central process control module sends a command to the programmable pulse inversion power supply to switch its output to reverse pulse mode. In this mode, the polarity of the power supply output is reversed, causing the polarity of the working electrode to change from cathode to anode, and the polarity of the counter electrode to change from anode to cathode. The duration of this stage is significantly shorter than that of the main reaction stage, and its specific value is determined by the central process control module based on sensor feedback signals (such as electrode potential changes) or preset time parameters.

[0063] The system rebalancing phase provides a stable initial chemical environment for the start of the next main reaction phase after the electrode activation phase. During this phase, the central process control module instructs the programmable pulse inversion power supply to stop current output and can selectively stop the ultrasonic transducer. This phase allows the ion concentration gradient and electrolysis products within the reactor to diffuse and redistribute. After a preset settling time, the central process control module starts the next operating cycle, re-entering the main reaction phase.

[0064] During the main reaction phase, the central process control module controls the programmable pulse inversion power supply to work in coordination with the ultrasonic transducer to construct a dynamic acoustic-electric coupling field within the dynamic pulse acoustic-electric reaction module in order to execute the coordinated reaction process.

[0065] In this stage, the ultrasonic transducer continuously emits high-frequency sound waves into the wastewater within the reactor, creating an ultrasonic field. This sound field induces acoustic cavitation in the liquid, resulting in the generation, growth, and instantaneous collapse of tiny bubbles. Upon collapse, these bubbles create localized regions of high temperature (thousands of Kelvin) and high pressure (hundreds of atmospheres), generating high-speed microjets. This physical energy can directly act on structurally stable water-soluble metal complexes in the wastewater. By stretching and breaking its coordination bonds, the complex dissociates, thereby releasing free metal ions (M) into the bulk liquid phase. n+ ) and organic fragments of the complexing agent (L frag The chemical formula for this process is: Simultaneously, a programmable pulse inversion power supply applies a positive pulse current to the working electrode and the counter electrode, making the working electrode the cathode and the counter electrode the anode, thus establishing an electric field within the reactor. Under the influence of this electric field, the free metal ions (M...) released by the aforementioned sonochemical process... n+ ) undergoes directional migration and an electrochemical reduction reaction occurs on the surface of the working electrode, which serves as the cathode, to produce zero-valent metal element (M (s) The cathode reaction is deposited in the form of ) within its massive three-dimensional porous structure. The expression for this cathode reaction is: Mn+ +ne - →M (s) ; At this stage, using pulsed current instead of constant direct current for electrolytic deposition has clear technical advantages. The intervals between pulses allow for effective recovery of the metal ion concentration on the electrode surface, thereby reducing concentration polarization and improving mass transfer efficiency. This enables the system to operate at higher limiting current densities and obtain a denser, smoother metal deposition layer, avoiding dendrite formation.

[0066] There is a significant synergistic effect between these two processes. First, the electrolytic reduction process at the cathode surface continuously consumes the released free metal ions M. n+ This reduces the concentration of the complex at the interface layer, causing the chemical equilibrium of the sonochemical complex-breaking reaction to continuously shift to the positive direction, thereby promoting the dissociation of more metal complexes. Secondly, the acoustic flow and microjets generated by the ultrasonic transducer violently agitate the diffusion layer on the surface of the working electrode, greatly enhancing the mass transfer rate of metal ions from the bulk liquid phase to the electrode surface, thereby improving the current efficiency and limiting current density of metal deposition.

[0067] Reference Appendix Figure 8 During the main reaction stage, an oxidation reaction occurs on the surface of the counter electrode, which serves as the anode. Water molecules are oxidized to produce oxygen, and simultaneously, organic fragments of the complexing agent L dissociated from the complex are also produced. frag An electrochemical advanced oxidation reaction also occurs on the anode surface, where the material is mineralized and decomposed into inorganic small molecules such as carbon dioxide and water. The expression for this anode reaction is: L frag +H₂O→CO₂+H₂O+H + +e - ; The cation-selective membrane, positioned between the working electrode region and the counter electrode region, plays a crucial role in regional separation at this stage. It selectively allows the metal cations M generated by the sonochemical process to pass through. n+ The cathode metal migrates from the counter electrode region or the bulk liquid phase to the working electrode region, effectively preventing oxidative intermediates generated in the counter electrode region and larger organic molecules from entering the working electrode region. This ensures that the cathode metal deposition process is not disturbed by oxidizing substances, maintaining the purity of the deposited metal.

[0068] Reference Appendix Figure 9 During the electrode activation stage, the central process control module instructs the programmable pulse inversion power supply to output a reverse pulse current, causing the polarity of the electrodes within the dynamic pulse acoustic-electrochemical reaction module to reverse. Specifically, the working electrode, which serves as the cathode during the main reaction stage, is switched to the anode, while the counter electrode, which serves as the anode during the main reaction stage, is switched to the cathode. This stage aims to remove the passivation layer accumulated on the surface of the working electrode during the main reaction stage in situ via electrochemical means.

[0069] When the working electrode is used as the anode, two parallel electrochemical and chemical processes occur on its surface to achieve the removal of different types of pollutants.

[0070] First, regarding the complexing agent organic fragments L adsorbed on the porous surface of the main reaction stage... frag The high anodic potential on the working electrode surface, along with other organic pollutants, triggers a direct electrochemical oxidation reaction. In this reaction, these organic molecules lose electrons, undergo deep oxidation, and ultimately mineralize and decompose into inorganic small molecules such as carbon dioxide and water, thus being effectively stripped from the electrode surface. The general expression for this process is: Secondly, when the working electrode is used as the anode, an electrolysis reaction of water occurs on its surface, producing oxygen and hydrogen ions (H+). + As shown in the following formula: 2H₂O→O₂+4H + +4e - ; The hydrogen ions (H+) generated in this reaction + This will result in the formation of a locally strongly acidic microenvironment within the three-dimensional porous structure of the working electrode, particularly at the electrode / solution interface. This acidic environment can suppress the metal hydroxides (M(OH)) that precipitate due to the localized pH increase during the main reaction stage. n The hydrogen ions (H+) generated in this reaction are precipitated again. + This will result in the formation of a locally strongly acidic microenvironment within the three-dimensional porous structure of the working electrode, particularly at the electrode / solution interface. This acidic environment can suppress the metal hydroxides (M(OH)) that precipitate due to the localized pH increase during the main reaction stage. n The precipitate is redissolved, allowing it to be in the form of soluble metal ions (M). n+ The solution returns to the liquid phase in its original form. The chemical expression for this dissolution process is: M(OH) n +nH + →M n+ +nH2O; Through the synergistic effect of the above-mentioned anodic oxidation stripping and local acid dissolution processes, the organic and inorganic passivation layers covering the working electrode surface are removed simultaneously, allowing its electrochemically active surface to be fully exposed and restored. The metal ions (M) that have redissolved into the solution are then removed. n+ The passivation layer can be reduced and deposited again in the next main reaction stage, realizing the recycling of materials within the system. The central process control module precisely controls the duration and pulse current parameters of this stage according to a preset program to ensure the complete removal of the passivation layer while avoiding excessive electrochemical corrosion of the electrode substrate.

[0071] To further illustrate the present invention, the operation method of the electroplating wastewater treatment system of the present invention will be described below through a specific embodiment.

[0072] Example 1 This embodiment aims to treat a simulated electroplating wastewater containing a copper ethylenediaminetetraacetate (Cu-EDTA) complex. The initial parameters of the wastewater are: total copper ion concentration of 150 mg / L, chemical oxygen demand (COD) of 600 mg / L, pH of 4.5, and a small amount of suspended solids.

[0073] The electroplating wastewater treatment system of the present invention is used to treat the above-mentioned wastewater. The specific, non-limiting operating parameters set for each part of the system are as follows: Cycle settings for the central process control module: The duration of the main reaction phase is 25 minutes.

[0074] Electrode activation phase duration: 3 minutes.

[0075] The system rebalancing phase lasts for 2 minutes.

[0076] Total duration of a single complete work cycle: 30 minutes.

[0077] Parameter settings for the dynamic pulse acoustic-electric response module: Ultrasonic transducer: operating frequency 25kHz, output acoustic power density 100W / L.

[0078] Programmable pulse inversion power supply: During the main reaction stage (working electrode is cathode): a positive pulse current is output with a current density of 30 A / m. 2 The frequency is 500Hz and the duty cycle is 80%.

[0079] During the electrode activation phase (working electrode is the anode): output a reverse pulse current with a current density of 15 A / m. 2 The frequency is Hz and the duty cycle is 50%.

[0080] Parameter settings for the resource recovery and electrode regeneration module: The electrolyte in the acidic electrolytic stripping tank is a 0.5 mol / L sulfuric acid solution.

[0081] DC power supply: constant voltage output, voltage value is 3.0V.

[0082] The specific implementation process of this system is as follows: First, the wastewater to be treated is pumped into the physical pretreatment module. The wastewater flows through an internal filter plate, where suspended solids are effectively retained. The pretreated, clarified wastewater is then introduced into the dynamic pulse acoustic-electric reaction module.

[0083] The central process control module initiates its first working cycle, entering the main reaction stage. It instructs the programmable pulse inversion power supply to output a forward pulse current according to preset parameters, and simultaneously instructs the ultrasonic transducer to start. Under the influence of the acoustic-electric synergistic field, the coordination bonds of the Cu-EDTA complex are opened, releasing free copper ions (Cu). 2+ Cu 2+ Under the influence of an electric field, it passes through the cation-selective membrane, migrates towards the working electrode which serves as the cathode, and is reduced to metallic copper (Cu) on its graphite felt surface. (s) It settles down. This process lasts 25 minutes.

[0084] After the main reaction stage, the central process control module automatically switches to the electrode activation stage. The output polarity of the programmable pulse inversion power supply is reversed, and the working electrode becomes the anode. On its surface, the adsorbed EDTA organic fragments are electrochemically oxidized and decomposed. At the same time, the small amount of copper hydroxide precipitate that may have formed due to the local pH increase is also redissolved by the local acidic environment generated by the oxygen evolution reaction at the anode. This process lasts for 3 minutes, effectively restoring the surface activity of the working electrode.

[0085] Subsequently, the system enters a two-minute system rebalancing phase, during which both the power supply and ultrasound cease operation to facilitate a stable start to the next cycle.

[0086] The aforementioned 30-minute work cycle was continuously repeated. After the wastewater remained in the system for a sufficient period of time, it was discharged from the outlet of the dynamic pulse-electroacoustic reaction module. Testing showed that the total copper ion concentration in the final treated water was below 0.5 mg / L, and the COD removal rate exceeded 90%.

[0087] After several system cycles, the central process control module pauses system operation based on preset conditions (e.g., the weight increment of the working electrode reaches a set threshold). The operator removes the copper-enriched working electrode from the reactor and installs it as the anode in the acidic electrolytic stripping tank of the resource recovery and electrode regeneration module, placing it on a stainless steel cathode plate. The DC power supply is activated, and the copper on the working electrode is electrolytically dissolved and redeposited on the stainless steel cathode plate as a copper layer with a purity higher than 99.9%. The copper-stripped working electrode substrate can be cleaned and reused in the system.

[0088] Example 2 This embodiment aims to treat precious metal electroplating rinsing wastewater containing potassium gold cyanide (KAu(CN)2). The initial parameters of the wastewater are: total gold ion concentration of 50 mq / L, total cyanide concentration of 120 mq / L, and pH value of 10.5.

[0089] When using the system described in this invention for processing, the following operating parameters are mainly adjusted: The cycle settings for the central process control module are: 40 minutes for the main reaction stage, 2 minutes for the electrode activation stage, and 3 minutes for the system rebalancing stage.

[0090] Parameter settings for the dynamic pulse acoustic-electric response module: Ultrasonic transducer: operating frequency 40kHz, output acoustic power density 120W / L.

[0091] Programmable pulse inversion power supply: Main reaction stage: positive pulse current, current density 15A / m 2 The frequency is 800Hz and the duty cycle is 75%.

[0092] Electrode activation phase: reverse pulse current, current density 10 A / m 2 100Hz frequency, 40% duty cycle.

[0093] After treatment, the total gold ion concentration in the final discharged water is below 0.1 mg / L. Cyanide is simultaneously degraded through sonochemical and anodic oxidation, with the total cyanide concentration below 0.5 mg / L. The gold-enriched working electrode is transferred to the resource recovery and electrode regeneration module, where it undergoes anodic stripping in a cyanide electrolyte system to recover high-purity sponge gold.

[0094] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A system for treating electroplating wastewater, characterized by, The system comprises: a reactor as a physical space for reaction; a working electrode and a counter electrode arranged in the reactor; an ultrasonic transducer for generating an ultrasonic field in the reactor; an ion-selective membrane arranged between the working electrode and the counter electrode; a programmable pulse-reversal power supply electrically connected with the working electrode and the counter electrode, for providing a pulse current with reversible output polarity in a preset period; a central process controller signal-connected with the programmable pulse-reversal power supply and the ultrasonic transducer.

2. The electroplating wastewater treatment system of claim 1, wherein, The central process controller is configured to control the programmable pulse-reversal power supply to cyclically execute a main reaction stage and an electrode activation stage in each preset period; in the main reaction stage, the working electrode functions as a cathode; in the electrode activation stage, the working electrode functions as an anode.

3. The electroplating wastewater treatment system of claim 2, wherein, In the main reaction stage, the ultrasonic transducer is used to generate an ultrasonic field to break metal complexes in wastewater by means of sonochemical effect, and meanwhile, the working electrode as a cathode is used to electrolytically reduce and deposit metal ions released from the metal complexes.

4. The electroplating wastewater treatment system of claim 2, wherein In the electrode activation stage, the working electrode as an anode is used to electrochemically oxidize and strip organic pollutants adsorbed on its surface, and to acidically dissolve the formed metal hydroxide.

5. The electroplating wastewater treatment system of claim 2, wherein, The central process controller is further configured to regulate the time length of the main reaction stage and the electrode activation stage, the current density output by the programmable pulse-reversal power supply, and the ultrasonic power output by the ultrasonic transducer according to a preset algorithm or feedback signals from sensors; The sensors include differential pressure sensors arranged at both ends of a physical pretreatment module for monitoring the degree of filter plate clogging, and monitoring sensors arranged inside a dynamic pulsed acoustic electric reaction module for monitoring pH value, oxidation-reduction potential (ORP), and conductivity in wastewater; The preset algorithm is configured to trigger and close-loop control the electrode activation stage on demand according to feedback signals representing the real-time surface state of the working electrode, and to dynamically optimize the current density and the ultrasonic power according to feedback signals representing the real-time efficiency of the metal deposition process during the main reaction stage.

6. The electroplating wastewater treatment system of claim 1, wherein, The working electrode is a three-dimensional porous electrode.

7. The electroplating wastewater treatment system of claim 1, wherein, The ion-selective membrane is a cation-selective membrane.

8. The electroplating wastewater treatment system of claim 1, wherein, The system further comprises a physical pretreatment module arranged upstream of a water inlet of the reactor for removing suspended solids in wastewater.

9. The electroplating wastewater treatment system of claim 8, wherein, The physical pretreatment module comprises a plurality of detachably connected filter boxes, each of which is provided with a filter plate movable between a filtering area and a backup area, and a blowdown mechanism linked with the movement of the filter plate.

10. The electroplating wastewater treatment system of claim 1, wherein, The system further comprises a resource recovery and electrode regeneration module, which comprises an acidic electrolytic stripping tank for electrolyzing the metal-rich working electrode as an anode to strip metal.

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