Method and apparatus for treating wastewater containing heavy metal ions

Abstract

The application provides a treatment method and device for wastewater containing heavy metal ions, and the treatment method comprises the following steps: performing adsorption treatment on the wastewater containing heavy metal ions under the action of an electric field to obtain treated wastewater. The treatment method for wastewater containing heavy metal ions provided by the application can drive heavy metal ions to migrate to the inside of an adsorbent by using the electromigration effect in the adsorption treatment process, realizes efficient capture of the heavy metal ions, and improves the treatment efficiency of the heavy metal ions in the wastewater.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and particularly relates to a method and apparatus for treating wastewater containing heavy metal ions. Background Technology

[0002] With rapid industrialization, wastewater containing heavy metal ions has become one of the most serious threats to environmental pollution and human health. Its sources are extremely widespread, with large quantities discharged during the production processes of industries such as electroplating, metallurgy, battery manufacturing, leather processing, and pesticide production. The electroplating industry is particularly prominent, discharging hundreds of millions of tons of wastewater containing heavy metal ions annually. This type of wastewater typically contains copper ions (Cu). 2+ ), zinc ions (Zn) 2+ Nickel ions (Ni) 2+ ), hexavalent chromium (Cr) 6+ ), cadmium ions (Cd) 2+ It contains various toxic heavy metal components, including ions that accumulate in the human body through the food chain. These heavy metal ions are difficult to metabolize and excrete, and can cause continuous damage to multiple key organs and physiological systems such as the nervous system, hematopoietic system, kidneys, and liver, leading to various acute and chronic diseases. They also have significant carcinogenic, teratogenic, and mutagenic risks, seriously endangering human life and health.

[0003] Therefore, developing efficient methods for treating wastewater containing heavy metal ions to achieve deep purification and resource recovery of heavy metal ions has become a key issue that urgently needs to be addressed in the field of environmental protection. Summary of the Invention

[0004] The main objective of this invention is to provide a method for treating wastewater containing heavy metal ions, which can improve the treatment efficiency of heavy metal ions in wastewater.

[0005] The present invention also provides a wastewater treatment device containing heavy metal ions, which can improve the treatment efficiency of heavy metal ions in wastewater.

[0006] In a first aspect, the present invention provides a method for treating wastewater containing heavy metal ions, comprising the following steps:

[0007] Wastewater containing heavy metal ions is adsorbed under the action of an electric field to obtain treated wastewater.

[0008] In the treatment method described above, the voltage applied by the electric field is 0.5~3V, and the direction of the electric field is consistent with the flow direction of the wastewater containing heavy metal ions.

[0009] As described above, the flow rate of the wastewater containing heavy metal ions fluctuates periodically.

[0010] The periodic fluctuation has a period of 5 to 40 minutes, and the flow rate of the wastewater containing heavy metal ions is 40 to 60 L / min.

[0011] The adsorbent used in the adsorption treatment, as described above, includes metal-organic framework-aerogel composite materials.

[0012] Among them, the metal-organic framework material includes ZIF-8, and the aerogel includes silica aerogel;

[0013] And / or, the adsorbent used in the adsorption treatment includes at least one of amino, carboxyl, and sulfonic acid groups.

[0014] In the treatment method described above, the particle size of the adsorbent used in the adsorption treatment exhibits a power-law distribution.

[0015] The treatment method described above further includes monitoring at least one of the pH value, concentration of heavy metal ions, flow rate, and pressure of the wastewater containing heavy metal ions.

[0016] As described above, the heavy metal ions in the wastewater containing heavy metal ions include at least one of lead ions, copper ions, zinc ions, chromium ions, nickel ions, and cadmium ions.

[0017] And / or, the concentration of heavy metal ions in the wastewater containing heavy metal ions is 1~1000 mg / L;

[0018] And / or, the pH value of the wastewater containing heavy metal ions is 4 to 6.

[0019] In a second aspect, the present invention provides an apparatus for performing the processing method described above, comprising an adsorption unit, the adsorption unit comprising a housing, an anode electrode plate located on the inner wall of the housing, and a cathode electrode column located at the center of the housing.

[0020] The device described above also includes N flow control units, where N ≥ 1.

[0021] The device described above further includes at least one of a pH monitoring unit, a differential pressure monitoring unit, and a concentration monitoring unit.

[0022] The wastewater treatment method for heavy metal ions provided by this invention applies an electric field during the adsorption process, which utilizes the electromigration effect to drive heavy metal ions to migrate into the adsorbent, thereby achieving efficient capture of heavy metal ions and improving the treatment efficiency of heavy metal ions in wastewater. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a wastewater treatment device containing heavy metal ions provided by the present invention.

[0025] Explanation of reference numerals in the attached figures:

[0026] 10 - Adsorption unit; 1: Anode electrode plate; 2: Cathode electrode column; 31: First flow control unit; 32: Second flow control unit; 33: Third flow control unit; 34: Fourth flow control unit; 35: Fifth flow control unit; 36: Sixth flow control unit; 4: pH monitoring unit; 51: First differential pressure monitoring unit; 52: Second differential pressure monitoring unit; 6: Concentration monitoring unit; 71: First inlet; 72: Second inlet; 73: Third inlet; 74: Fourth inlet; 75: Fifth inlet; 76: Sixth inlet; 8: Outlet. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0028] Heavy metal ion-contaminated wastewater is one of the major industrial wastewaters that pollute the environment and threaten human health. Its sources are widespread, including industries such as electroplating, metallurgy, batteries, leather, and pesticides, with electroplating being particularly prominent, discharging hundreds of millions of tons annually. This type of wastewater often contains Cu. 2+ Zn 2+ Ni 2+ Cr 6+ Cd 2+ It contains various highly toxic heavy metal ions, which are non-degradable, bioaccumulate, and migrate over long distances. They can enter the human body through the food chain, causing serious damage to multiple organs and systems, and are extremely harmful.

[0029] To address this serious challenge, the industry has developed various treatment technologies. Chemical precipitation involves adding reagents to form heavy metal hydroxides or sulfides as precipitates, but it suffers from problems such as large sludge production, secondary pollution, and difficulties in metal recovery. Electrochemical methods offer better treatment results, but rely on high energy input and have high electrode maintenance costs. Ion exchange methods, while exhibiting good selectivity for specific ions, are limited by the resin's susceptibility to contamination and frequent regeneration, hindering large-scale engineering applications. Membrane separation technology can achieve deep purification, but faces challenges such as membrane module fouling, high operating energy consumption, and high investment costs. In contrast, adsorption methods, due to their ease of operation, relatively low cost, and wide availability of adsorbents, have become the most widely used deep treatment technology. However, current adsorption methods still suffer from low adsorption efficiency for heavy metal ions.

[0030] The inventors of this application have discovered through research that applying an electric field during the wastewater adsorption treatment process can significantly improve the treatment efficiency of heavy metal ions in wastewater.

[0031] Based on this, in a first aspect, the present invention provides a method for treating wastewater containing heavy metal ions, comprising the following steps: subjecting wastewater containing heavy metal ions to adsorption treatment under the action of an electric field to obtain treated wastewater.

[0032] In the process of adsorbing wastewater containing heavy metal ions, this invention applies an electric field to drive the heavy metal ions to migrate into the adsorbent through electromigration, thereby achieving efficient capture of heavy metal ions, shortening the time to reach adsorption equilibrium, and significantly improving the treatment efficiency of heavy metal ions in wastewater containing heavy metal ions, that is, improving the removal rate of heavy metal ions.

[0033] Therefore, the wastewater treatment method for heavy metal ions provided by the present invention can drive heavy metal ions to migrate into the adsorbent by applying an electric field during the adsorption process, thereby achieving efficient capture of heavy metal ions and improving the treatment efficiency of heavy metal ions in wastewater.

[0034] In some embodiments of the present invention, the voltage applied by the electric field is 0.5 to 3V, for example, it can be a range of 0.5V, 1V, 1.5V, 2V, 2.5V, 3V, or any combination thereof. The direction of the electric field is consistent with the flow direction of the wastewater containing heavy metal ions.

[0035] In this invention, the direction of the electric field is consistent with the flow direction of the wastewater containing heavy metal ions, which can further drive the heavy metal ions to migrate into the adsorbent, thereby further improving the treatment efficiency of heavy metal ions in wastewater.

[0036] Furthermore, the voltage applied by the electric field is within the aforementioned range, meaning the applied electric field is relatively weak. This can drive heavy metal ions to migrate into the adsorbent, reduce energy consumption, avoid electrode passivation, and improve economic efficiency and long-term operational stability.

[0037] In some embodiments of the present invention, the flow rate of wastewater containing heavy metal ions exhibits periodic fluctuations; the period of the periodic fluctuation is 5 to 40 minutes, for example, it can be a range of 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes or any two of these; the flow rate of wastewater containing heavy metal ions is 40 to 60 L / min, for example, it can be a range of 40 L / min, 45 L / min, 50 L / min, 55 L / min, 60 L / min or any two of these.

[0038] In this invention, the flow rate of wastewater containing heavy metal ions fluctuates periodically, which can break the stable flow field structure during the adsorption process, eliminate the "dead zone" in the adsorption process, and improve the contact efficiency between the fluid and the adsorbent.

[0039] Specifically, a sinusoidal fluctuation (40~60 mL / min) or trapezoidal fluctuation mode can be used to periodically change the flow rate (period of 5~40 min). This technology increases the surface renewal rate of the adsorbent by periodically disturbing the flow field, thereby reducing boundary layer resistance and enhancing mass transfer efficiency.

[0040] In some embodiments of the present invention, the adsorbent used in the adsorption treatment includes a metal-organic framework-aerogel composite material; wherein the metal-organic framework includes ZIF-8, and the aerogel includes silica aerogel.

[0041] In some embodiments, the adsorbent used in the adsorption treatment includes at least one of amino, carboxyl, and sulfonic acid groups.

[0042] In this invention, the adsorbent comprises a composite material formed from a metal-organic framework (MOF) and an aerogel. The MOF includes ZIF-8, and the aerogel includes silica aerogel, which can be hydrophobically treated. Introducing at least one group selected from amino, carboxyl, and sulfonic acid groups into the adsorbent can provide abundant adsorption sites for heavy metal ions, further improving the treatment efficiency and removal rate of heavy metal ions.

[0043] The specific surface area of ​​the adsorbent can be 350~700m². 2 The adsorbent has a pore volume of 0.05~0.6mL / g, an average pore size of 0.2~3nm, and uniform particle size ranging from 0.5~10.0mm, enabling efficient capture of heavy metal ions.

[0044] In some embodiments of the present invention, the particle size of the adsorbent used in the adsorption treatment is power-law distributed.

[0045] I understand that a power-law distribution refers to a variable that has a distributional property, and its probability density function is a power function.

[0046] In this invention, particles of different sizes are mixed evenly to make the particle size and number of particles exhibit a power-law distribution, which can improve pore connectivity, reduce adsorption resistance, improve the internal mass transfer efficiency of the adsorbent, and reduce pressure drop fluctuations.

[0047] In some embodiments of the present invention, the method further includes monitoring at least one of the pH value, concentration of heavy metal ions, flow rate, and pressure of the wastewater containing heavy metal ions.

[0048] In this invention, the pH value of wastewater containing heavy metal ions is monitored, especially for wastewater containing heavy metal ions that undergo adsorption treatment. This allows for control of the acidity and alkalinity of the wastewater containing heavy metal ions undergoing adsorption treatment, thereby improving the adsorption selectivity of the adsorbent.

[0049] By monitoring the concentration of heavy metal ions, the removal rate can be calculated. Based on this removal rate, the flow rate of the wastewater containing heavy metal ions undergoing adsorption treatment can be adjusted in real time to maintain a high removal rate. For example, when the removal rate is low, the flow rate of the wastewater undergoing adsorption treatment can be reduced, thus extending the retention time and improving the removal rate.

[0050] Monitoring the flow rate and pressure of wastewater containing heavy metal ions allows for adjustments to these parameters as needed, maintaining a high removal rate of heavy metal ions. It also helps to predict the adsorption saturation state of the adsorbent and trigger regeneration or replacement operations.

[0051] In some embodiments of the present invention, the heavy metal ions in the wastewater containing heavy metal ions include at least one of lead ions, copper ions, zinc ions, chromium ions, nickel ions, and cadmium ions.

[0052] In this invention, the types of heavy metal ions are within the above-mentioned range. Under the action of the above-mentioned adsorbent, the synergistic capture of multiple heavy metal ions can be achieved, thereby improving the removal rate of heavy metal ions.

[0053] In some embodiments, the concentration of heavy metal ions in the wastewater containing heavy metal ions is 1 to 1000 mg / L, for example, it can be a range of 1 mg / L, 10 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, 800 mg / L, 1000 mg / L or any combination thereof.

[0054] The concentration of heavy metal ions in this invention is within the above-mentioned range, and the above-mentioned method for treating wastewater containing heavy metal ions can be applied to a wide range of heavy metal ion concentrations.

[0055] In some embodiments, the pH value of the wastewater containing heavy metal ions is 4 to 6, for example, it can be a range of 4, 4.5, 5, 5.5, 6 or any two of them.

[0056] This pH range design allows the functional groups on the adsorbent surface to be in an optimal adsorption state, while preventing the precipitation of metal hydroxides that could clog the adsorbent pores and improving the selectivity of the adsorbent.

[0057] Secondly, the present invention provides an apparatus for performing the processing method described above, such as... Figure 1 As shown, it includes an adsorption unit 10, which includes a housing, an anode electrode plate 1 located on the inner wall of the housing, and a cathode electrode column 2 located at the center of the housing.

[0058] The wastewater treatment device for heavy metal ions of the present invention includes an adsorption unit 10. The adsorption unit 10 includes a shell, such as an plexiglass cylinder. Stainless steel wire mesh is installed as circumferential dividing members at locations 0.5-1.5 cm from the inner wall and 0.5-1.5 cm from the center inside the shell to support and fix the adsorbent and ensure uniform fluid permeability. An anode electrode 1, for example, a titanium-coated ruthenium oxide (Ti / RuO2) anode electrode 1, is installed in close contact with the inner wall of the shell. A cathode electrode post 2, such as graphite, is disposed at the center of the shell. The area between the outer dividing member and the inner wall is the inlet water distribution area, and the area between the inner dividing member and the cathode electrode post 2 is the effluent collection area. An outlet 8 is located at the top of the effluent collection area. The inlet water distribution area can have N inlets, where N≥1. When N=6, the inlet water distribution area has 6 inlets, namely, the first inlet 71, the second inlet 72, the third inlet 73, the fourth inlet 74, the fifth inlet 75, and the sixth inlet 76.

[0059] Specifically, wastewater containing heavy metal ions, after pH adjustment, enters the adsorption unit 10 simultaneously through multiple inlets at a periodically varying flow rate. The wastewater, now free of heavy metal ions, flows out through the outlet 8 at the top of the adsorption unit 10. A low voltage (e.g., 0.5-3V) is applied between the anode and cathode, creating a weak DC electric field. This electric field is aligned with the water flow direction, utilizing electromigration to drive heavy metal ions towards the negatively charged cathode (i.e., the adsorbent direction), thus enabling efficient capture of the heavy metal ions by the adsorbent.

[0060] The aforementioned anode electrode sheet and cathode electrode column have strong corrosion resistance and good conductivity, which can extend the service life of the device.

[0061] In some embodiments of the present invention, the above-mentioned device further includes N flow control units, where N≥1, for example, which can be a range consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or any two of them.

[0062] In one implementation, such as Figure 1 As shown, the device includes six flow control units: a first flow control unit 31, a second flow control unit 32, a third flow control unit 33, a fourth flow control unit 34, a fifth flow control unit 35, and a sixth flow control unit 36. Each of the six flow control units is connected to a different inlet. For example, the first flow control unit 31 is connected to the first inlet 71, the second flow control unit 32 is connected to the second inlet 72, the third flow control unit 33 is connected to the third inlet 73, the fourth flow control unit 34 is connected to the fourth inlet 74, the fifth flow control unit 35 is connected to the fifth inlet 75, and the sixth flow control unit 36 ​​is connected to the sixth inlet 76.

[0063] In this invention, N flow control units are used, i.e., a multi-channel design is adopted, which can realize the flow rate of wastewater containing heavy metal ions fluctuates periodically, improve the contact efficiency between wastewater and adsorbent, improve the adsorption efficiency of adsorbent, and improve the removal rate of heavy metals.

[0064] In some embodiments of the present invention, the above-mentioned device further includes at least one of a pH monitoring unit 4, a differential pressure monitoring unit, and a concentration monitoring unit 6.

[0065] In one implementation, such as Figure 1 As shown, the unit includes two differential pressure monitoring units: a first differential pressure monitoring unit 51 installed at the inlet and a second differential pressure monitoring unit 52 installed at the outlet. This allows for pressure adjustment based on the monitored wastewater pressure at the inlet and outlet, improving the adsorption efficiency of the adsorbent and increasing the removal rate of heavy metal ions. A concentration monitoring unit 6 installed at the outlet monitors the concentration of heavy metal ions at the outlet, facilitating the calculation of the heavy metal ion removal rate. A pH monitoring unit 4 installed at the inlet monitors the pH value of the wastewater containing heavy metal ions entering the adsorption unit in real time. This ensures that the functional groups on the adsorbent surface are in an optimal adsorption state, while preventing the precipitation of metal hydroxides that could clog the adsorbent pores and improving the selectivity of the adsorbent.

[0066] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0067] Example 1

[0068] Object of treatment: A copper (Cu) plating plant 2+ ) and nickel (Ni 2+ The initial concentration of heavy metal ions in the wastewater was 150 mg / L.

[0069] like Figure 1 As shown, specifically, the adsorption unit 10 is installed and fixed. The adsorption unit 10 is made of an organic glass cylinder with an inner diameter of 10 cm and a height of 50 cm. Stainless steel wire mesh is installed as circumferential dividing members at points 0.5 cm from the inner wall and 1.0 cm from the center inside the device to support and fix the adsorbent and ensure uniform fluid permeability. A titanium-coated ruthenium oxide (Ti / RuO2) anode electrode 1 is tightly attached to the inner wall of the adsorption unit 10. A graphite cathode electrode post 2 is placed at the center of the adsorption unit. The area between the outer dividing member and the inner wall is the inlet water distribution area, and the area between the inner dividing member and the cathode electrode post 2 is the outlet water collection area.

[0070] An adsorbent is filled in the area between two layers of stainless steel wire mesh. Specifically, the adsorbent is a metal-organic framework-aerogel composite material, with the metal-organic framework being ZIF-8 and the aerogel being silica aerogel. The adsorbent includes amino, carboxyl, and sulfonic acid groups, and its specific surface area is approximately 550 m². 2 / g, with an average pore size of 1.8nm. The particles were sieved, and particles with a diameter in the range of 1.0-2.0mm were selected. They were then mixed and packed according to different particle sizes in a power-law distribution (40% of particles with a diameter of 1.0-1.5mm, 30% of particles with a diameter of 1.5-2.0mm, 20% of particles with a diameter of 2.0-3.0mm, and 10% of particles with a diameter of 3.0-4.0mm) to optimize the pore structure of the adsorbent.

[0071] Create a weak electric field. Connect the positive and negative terminals of the DC regulated power supply to the anode electrode plate and the cathode electrode column, respectively.

[0072] A first differential pressure monitoring unit 51 (first pressure sensor), a pH monitoring unit 4 (pH sensor), and six flow control units (six flow control valves) are installed on the inlet pipe, namely, the first flow control unit 31, the second flow control unit 32, the third flow control unit 33, the fourth flow control unit 34, the fifth flow control unit 35, and the sixth flow control unit 36. A concentration monitoring unit 6 (online heavy metal ion detector, i.e., using copper and nickel ion specific electrodes) and a second differential pressure monitoring unit 52 (second pressure sensor) are installed on the outlet pipe. The six flow control units are connected to six different inlets, namely, the first flow control unit 31 is connected to the first inlet 71, the second flow control unit 32 is connected to the second inlet 72, the third flow control unit 33 is connected to the third inlet 73, the fourth flow control unit 34 is connected to the fourth inlet 74, the fifth flow control unit 35 is connected to the fifth inlet 75, and the sixth flow control unit 36 ​​is connected to the sixth inlet 76. An outlet 8 is located above the cathode electrode column 2. The first differential pressure monitoring unit 51, the second differential pressure monitoring unit 52, the pH monitoring unit 4, the six flow control units, and the concentration monitoring unit 6 are all connected to an industrial computer and have built-in control programs.

[0073] The treatment method for wastewater containing heavy metal ions includes the following steps:

[0074] First, the pH of the wastewater containing heavy metal ions was adjusted to 5.0 using NaOH solution. Next, the flow control unit was activated, allowing the wastewater to enter adsorption unit 10 at a flow rate of 50 mL / min. Simultaneously, a dynamic flow field control program was initiated, causing the flow rate of the wastewater containing heavy metal ions to fluctuate sinusoidally between 40 mL / min and 60 mL / min over a 5-minute period. Then, a constant voltage of 1.5V was applied to the DC power supply, ensuring the electric field direction was aligned with the flow direction of the wastewater containing heavy metal ions. Simultaneously, the intelligent control system was activated to monitor and adjust the pH, flow rate, and pressure of the influent, as well as the concentration and pressure of heavy metal ions in the effluent, in real time.

[0075] Monitoring revealed that in the initial stage, Cu 2+ and Ni 2+ The removal rate remained stable at over 98%. After 20 hours of continuous operation, the Cu content was calculated. 2+ and Ni 2+ The removal rate decreased to 92%. The influent flow rate was gradually reduced from 50 mL / min to 35 mL / min, effectively extending the average residence time of the wastewater in adsorption unit 10 from 60 min to 86 min. After the flow rate adjustment, the Cu in the effluent... 2+ and Ni 2+As the concentration decreases, the removal rate recovers to 96%. The system maintains this flow rate until the adsorbent is near saturation and requires regeneration or replacement. Removal rate = (initial heavy metal ion concentration - outlet heavy metal ion concentration) / initial heavy metal ion concentration.

[0076] Example 2

[0077] The treatment method and apparatus for wastewater containing heavy metal ions in Example 2 are basically the same as those in Example 1, except that a constant voltage of 0.5V is applied.

[0078] Monitoring revealed that in the initial stage, Cu 2+ and Ni 2+ The removal rate remained stable at over 96.5%. After 20 hours of continuous operation, the Cu content was calculated. 2+ and Ni 2+ The removal rate decreased to 90.3%. The influent flow rate was gradually reduced from 50 mL / min to 25 mL / min, effectively extending the average residence time of the wastewater in adsorption unit 10 from 60 min to 120 min. After the flow rate adjustment, the Cu in the effluent... 2+ and Ni 2 + As the concentration decreases, the removal rate recovers to 93.2%. The system maintains this flow rate until the adsorbent is near saturation and needs to be regenerated or replaced.

[0079] Example 3

[0080] The treatment method and device for wastewater containing heavy metal ions in Example 3 are basically the same as those in Example 1. The difference is that a constant voltage of 3V is applied, and the flow rate of wastewater containing heavy metal ions fluctuates sinusoidally between 40mL / min and 60mL / min with a period of 40min.

[0081] Monitoring revealed that in the initial stage, Cu 2+ and Ni 2+ The removal rate remained stable at over 97.4%. After 20 hours of continuous operation, the Cu content was calculated. 2+ and Ni 2+ The removal rate decreased to 91.6%. The influent flow rate was gradually reduced from 50 mL / min to 45 mL / min, thus extending the average residence time of the wastewater in adsorption unit 10 from 60 min to 66.7 min. After the flow rate adjustment, the Cu in the effluent... 2+ and Ni 2+ As the concentration decreases, the removal rate recovers to 95.2%. The system maintains this flow rate until the adsorbent is near saturation and needs to be regenerated or replaced.

[0082] Example 4

[0083] The treatment method and device for wastewater containing heavy metal ions in Example 4 are basically the same as those in Example 1, except that the initial concentration of heavy metal ions is 1 mg / L and the pH value is adjusted to 4.

[0084] Monitoring revealed that in the initial stage, Cu 2+ and Ni 2+ The removal rate remained stable at over 82%. After 20 hours of continuous operation, the Cu content was calculated. 2+ and Ni 2+ The removal rate decreased to 73%. The influent flow rate was gradually reduced from 50 mL / min to 35 mL / min, effectively extending the average residence time of the wastewater in adsorption unit 10 from 60 min to 86 min. After the flow rate adjustment, the Cu in the effluent... 2+ and Ni 2+ As the concentration decreases, the removal rate recovers to 78%, and the system maintains this flow rate until the adsorbent is close to saturation and needs to be regenerated or replaced.

[0085] Example 5

[0086] The treatment method and device for wastewater containing heavy metal ions in Example 5 are basically the same as those in Example 1, except that the initial concentration of heavy metal ions is 1000 mg / L and the pH value is adjusted to 6.

[0087] Monitoring revealed that in the initial stage, Cu 2+ and Ni 2+ The removal rate remained stable at over 98.6%. After 20 hours of continuous operation, the Cu content was calculated. 2+ and Ni 2+ The removal rate decreased to 93.0%. The influent flow rate was gradually reduced from 50 mL / min to 25 mL / min, effectively extending the average residence time of the wastewater in adsorption unit 10 from 60 min to 120 min. After the flow rate adjustment, the Cu in the effluent... 2+ and Ni 2 + As the concentration decreases, the removal rate recovers to 96.5%. The system maintains this flow rate until the adsorbent is near saturation and needs to be regenerated or replaced.

[0088] Comparative Example 1

[0089] The treatment method and apparatus for wastewater containing heavy metal ions in Comparative Example 1 and Example 1 are basically the same, except that the apparatus does not include an anode electrode plate and a cathode electrode column, that is, no electric field is applied during the adsorption treatment of wastewater containing heavy metal ions.

[0090] Monitoring revealed that in the initial stage, Cu 2+ and Ni 2+The removal rate remained stable at over 88%. After 20 hours of continuous operation, the calculated Cu... 2+ and Ni 2+ The removal rate decreased to 71%. The influent flow rate was gradually reduced from 50 mL / min to 35 mL / min, effectively extending the average residence time of the wastewater in adsorption unit 10 from 60 min to 86 min. After the flow rate adjustment, the Cu in the effluent... 2+ and Ni 2+ As the concentration decreases, the removal rate recovers to 83%, and the system maintains this flow rate until the adsorbent is close to saturation and needs to be regenerated or replaced.

[0091] Therefore, compared with the comparative example, the wastewater treatment method containing heavy metal ions provided by the present invention can improve the treatment efficiency of heavy metal ions in wastewater by applying an electric field during the adsorption process, that is, the removal rate of heavy metal ions is higher.

[0092] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for treating wastewater containing heavy metal ions, characterized in that, Includes the following steps: Wastewater containing heavy metal ions is passed through an adsorption bed filled with adsorbent, and a DC electric field in the same direction as the wastewater flow is applied to the adsorption bed for adsorption treatment to obtain treated wastewater; wherein, the DC electric field is used to drive the heavy metal ions in the wastewater to migrate into the interior of the adsorbent. The voltage applied by the DC electric field is 0.5~3V; The flow rate of the wastewater containing heavy metal ions fluctuates periodically; the period of the periodic fluctuation is 5 to 40 minutes, and the flow rate of the wastewater containing heavy metal ions is 40 to 60 L / min. The adsorbent is a metal-organic framework-aerogel composite material; wherein the metal-organic framework is ZIF-8 and the aerogel is silica aerogel. The adsorbent includes at least one of amino, carboxyl, and sulfonic acid groups; The particle size of the adsorbent exhibits a power-law distribution; The specific surface area of ​​the adsorbent is 350~700 m². 2 / g, pore volume is 0.05~0.6mL / g, average pore size is 0.2~3nm, and the adsorbent particles are uniform in size with a particle size range of 0.5~10.0mm; The heavy metal ions in the wastewater containing heavy metal ions include at least one of lead ions, copper ions, zinc ions, chromium ions, nickel ions, and cadmium ions. The concentration of heavy metal ions in the wastewater containing heavy metal ions is 1~1000 mg / L; The pH value of the wastewater containing heavy metal ions is 4 to 6.

2. The processing method according to claim 1, characterized in that, Also includes: The pH value, concentration of heavy metal ions, flow rate, and pressure of the wastewater containing heavy metal ions are monitored.

3. An apparatus for performing the processing method according to claim 1 or 2, characterized in that, The device includes an adsorption unit, which comprises a housing, an anode electrode plate located on the inner wall of the housing, and a cathode electrode column located at the center of the housing.

4. The apparatus according to claim 3, characterized in that, It also includes N flow control units, where N≥1.

5. The apparatus according to claim 3 or 4, characterized in that, It also includes at least one of a pH monitoring unit, a differential pressure monitoring unit, and a concentration monitoring unit.

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