A device and method for recovering metal ions from wastewater

Abstract

The application provides a metal ion recovery device and method in wastewater, and belongs to the technical field of environmental protection. The device comprises a metal ion enrichment assembly. A cathode electrode plate is arranged on one side of the metal ion enrichment assembly, and an anode electrode plate is arranged on the other side. A plurality of groups of repeated units of cation membranes, metal ion adsorption compartments, anion membranes and metal ion enrichment chambers are arranged between the cathode electrode plate and the anode electrode plate. The cathode electrode plate and the cation membrane are separated into a cathode compartment, and the anode electrode plate and the anion membrane are separated into an anode compartment. The metal ion adsorption compartments are filled with metal ion selective resins. The bottom of the metal ion adsorption compartment in each repeated unit is connected with a wastewater buffer tank, and the top is connected with a metal ion concentration tank and a water production tank. The bottom and the top of the metal ion enrichment chamber in each repeated unit are respectively connected with the metal ion concentration tank. The application avoids a large amount of reagent consumption in the desorption process, and improves the metal ion concentration ratio.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a device and method for recovering metal ions from wastewater. BACKGROUND

[0002] Heavy metal electroplating wastewater and PCB wastewater contain various heavy metal pollutants mainly including copper, and the water quality to be treated is complex and the components are not easy to control. The wastewater contains cyanide, acid, alkali, hexavalent chromium, copper, zinc, cadmium, nickel, gold, silver and other heavy metal pollutants, which are highly toxic and some are toxic substances, and have carcinogenic, teratogenic and mutagenic effects, and are very harmful to human body.

[0003] Common methods for treating heavy metal electroplating wastewater and PCB wastewater include chemical precipitation method, oxidation-reduction method, adsorption method, membrane separation technology, ion exchange treatment method, biological treatment technology and the like, and each method has its advantages and disadvantages.

[0004] (1) Chemical method

[0005] The chemical method includes neutralization precipitation method, sulfide precipitation method and electrochemical method.

[0006] The neutralization precipitation method adjusts the pH value of the wastewater, so that the nickel ions form nickel hydroxide precipitate, and then the precipitate is removed by a solid-liquid separation device. Common neutralizing agents include lime and sodium hydroxide.

[0007] The sulfide precipitation method has great advantages in treating heavy metal wastewater, and can solve the problem of non-compliance of some weakly complex heavy metals, and has a wide pH value range for reaction. However, the sulfide precipitate is small and not easy to settle, which limits its application research. In addition, the presence of cyanide ions affects the precipitation of sulfide, and some sulfide precipitates are dissolved.

[0008] The ferrite precipitation method is developed on the basis of the ferrous sulfate method. FeSO4 can make various heavy metal ions form ferrite crystals and precipitate, and the general formula of ferrite is FeO·Fe2O3. The ferrite method for treating electroplating wastewater generally has three processes, namely reduction reaction, co-precipitation and formation of ferrite. The ferrite method can remove multiple heavy metal ions at one time, has good purification effect, simple equipment and convenient operation. However, it cannot recover heavy metals alone, consumes a lot of energy and takes a long time to treat.

[0009] (2) Ion exchange method

[0010] Ion exchange method is the process of ion exchange between heavy metal ions and ion exchange resin, and the performance of the resin has great influence on heavy metal removal. Commonly used ion exchange resins include cation exchange resin, anion exchange resin, chelating resin and humic acid resin, etc. The cation exchange resin is composed of polymeric anion and exchangeable cation. Ion exchange method has more application examples in treating nickel-containing wastewater. Ion exchange method is an important method for treating electroplating wastewater. It has the advantages of large treatment capacity, good effluent quality, and recycling of water and heavy metal resources. The disadvantages are that the resin is easily contaminated or oxidized, and the regeneration is frequent, and the operation cost is high.

[0011] (3) Electrolysis method

[0012] The basic principle of electrolysis method is that when electric current passes through electrolyte solution, the cations in the solution produce ion migration and electrode reaction, that is, the cations in the wastewater migrate to the cathode and produce reduction reaction on the cathode, so that the metal is deposited.

[0013] (4) Membrane separation method

[0014] The membrane method for treating industrial wastewater generally selects reverse osmosis, ultrafiltration and the combination technology of the two, and the key of the membrane method for treating industrial wastewater is to select appropriate membrane according to the separation conditions.

[0015] The traditional treatment method cannot meet the increasingly stringent environmental protection requirements (such as the requirement of 0.1 mg / l or less for the content of electroplating surface three nickel). And the copper element recovery process has large dosing amount, large operation difficulty, high cost, and easy to cause secondary pollution. SUMMARY

[0016] To solve the above problems, the application discloses a wastewater metal ion recovery device and recovery method, which utilizes the special functional groups of chelating resin and the characteristics of forming complex with heavy metal ions to realize the recycling and deep removal of heavy metal ions, avoids the large consumption of reagents in the desorption process, and improves the metal ion concentration ratio, and the metal ion concentration in the concentrated solution can reach 56g / L or more.

[0017] To achieve the above purpose, the technical scheme of the application is as follows:

[0018] The application discloses a metal ion recovery device in wastewater, which comprises a metal ion enrichment assembly, wherein one side of the metal ion enrichment assembly is provided with a cathode electrode plate, and the other side is provided with an anode electrode plate; a plurality of groups of repeated units of anion membranes, metal ion adsorption compartments, cation membranes and metal ion enrichment chambers are arranged between the cathode electrode plate and the anode electrode plate; the cathode electrode plate and the cation membrane are separated into a cathode compartment, and the anode electrode plate and the anion membrane are separated into an anode compartment; the metal ion adsorption compartment is filled with metal ion selective resin; the bottom of the metal ion adsorption compartment in each repeated unit is connected with a wastewater buffer tank through a pipeline, and the top of the metal ion adsorption compartment is connected with a metal ion concentration tank and a water production tank through a pipeline; the anode compartment is connected with an anode circulation tank through a circulation pipeline, and the cathode compartment is connected with a cathode circulation tank through a circulation pipeline; the bottom and the top of the metal ion enrichment chamber in each repeated unit are respectively connected with the metal ion concentration tank through a pipeline; the water production tank and the metal ion concentration tank are connected through a pipeline, and the water production tank and the wastewater buffer tank are connected through a pipeline.

[0019] Further, a wastewater lifting pump and an electroplating wastewater inlet valve are arranged on the outlet pipeline of the wastewater buffer tank.

[0020] Further, an anode circulation pump is arranged on the outlet pipeline of the anode circulation tank, and a cathode circulation pump is arranged on the outlet pipeline of the cathode circulation tank.

[0021] Further, a water production tank inlet valve and a metal ion concentration inlet valve are respectively arranged on the connecting pipelines of the water production tank and the metal ion concentration tank.

[0022] Further, a concentration regeneration inlet valve and a water production lifting pump are arranged on the connecting pipelines of the water production tank and the wastewater buffer tank.

[0023] Further, a metal ion concentration lifting pump is arranged on the connecting pipelines of the metal concentration tank and the repeated units.

[0024] The application further discloses a metal ion recovery method in wastewater by using the metal ion recovery device, and the method comprises a metal ion adsorption process and a metal ion desorption enrichment process, and specifically comprises the following steps.

[0025] Metal ion adsorption process: open the wastewater inlet valve, close the concentrated regeneration inlet valve, the wastewater stored in the wastewater buffer tank is lifted from the bottom of the metal ion enrichment assembly into the metal ion adsorption compartment by the wastewater lifting pump, the wastewater contacts the metal ion selective resin filled in the metal ion adsorption compartment, the metal ions in the wastewater are exchanged and adsorbed by the resin, the wastewater from which the metal ions are removed is collected by the pipeline and then flows out from the top of the metal ion enrichment assembly, when the liquid level of the metal ion concentration tank is lower than the set value, open the metal ion concentration tank water inlet automatic valve, close the water tank inlet valve, the wastewater enters the metal ion concentration tank, and the water required for metal ion concentration is stored, when the liquid level of the metal ion concentration tank is higher than the set value, close the metal ion concentration tank water inlet automatic valve, open the water tank inlet valve, the wastewater from which the metal ions are removed enters the water tank and then enters the next stage of treatment device as qualified water;

[0026] Nickel ion desorption enrichment process: when the metal ion selective resin filled in the metal ion adsorption compartment is saturated with metal ions, close the wastewater inlet valve, open the concentrated regeneration inlet valve, close the metal ion concentration tank water inlet automatic valve, open the water tank inlet valve, the water stored in the metal ion concentration tank is lifted by the metal ion concentration tank lifting pump and then enters the metal ion enrichment compartment from the bottom of the metal ion enrichment assembly and flows back to the metal ion concentration tank, and the water is lifted by the water lifting pump and then enters the metal ion adsorption compartment from the bottom of the metal ion enrichment assembly and flows back to the water tank; at the same time, the cathode circulating pump is started to lift the catholyte stored in the cathode circulating tank, the anode circulating pump is started to lift the anolyte stored in the anode circulating tank, and the two enter the cathode compartment and the anode compartment from the bottom of the metal ion enrichment assembly, respectively, and the effluent flows back to the cathode circulating tank and the anode circulating tank, respectively, and a direct current voltage is applied between the cathode and anode electrode plates of the metal ion enrichment assembly, the metal ions adsorbed by the metal ion selective resin move towards the cathode under the action of the electric field, the metal ions can pass through the cation membrane smoothly due to the selective permeability of the cation membrane, enter the metal ion enrichment compartment, and cannot further migrate due to the blockage of the anion membrane, are blocked in the metal ion enrichment compartment, and form enrichment, so that the concentration of the metal ions in the concentrated water reaches 56 g / L or more; the cation vacancies of the resin generated by the migration of the metal ions are replaced by sodium ions and hydrogen ions in the water entering the metal ion adsorption compartment, so as to realize the desorption and regeneration of the resin; the anions in the metal ion adsorption compartment pass through the anion membrane into the metal ion enrichment compartment under the action of the electric field, so as to realize the balance of the cations and anions. After the desorption of the system is completed, the metal ion adsorption stage is entered.

[0027] Further, the catholyte in the cathode circulating tank is a sodium chloride solution with a mass percentage concentration of 3%.

[0028] Further, the anolyte in the anode circulating tank is a sodium sulfate solution with a mass percentage concentration of 3%.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. This invention combines a metal ion selective adsorption ion exchange resin with an ion membrane to separate and concentrate gold ions in wastewater such as nickel or copper ions in electroplating wastewater or copper ions in PCB wastewater. This creates favorable conditions for extracting and recovering large amounts of nickel, copper and other metal resources from electroplating wastewater, and reduces heavy metal pollution to the environment caused by electroplating wastewater discharge.

[0031] 2. The enrichment and recovery of metal ions minimizes the consumption of reagents in the wastewater treatment process and also minimizes the amount of heavy metal sludge generated, thereby reducing wastewater treatment costs.

[0032] 3. The combination of ion exchange adsorption technology and electro-driven ion membrane desorption technology improves the desorption and regeneration efficiency of ion exchange resin, avoids the consumption of a large amount of reagents in the desorption process, and also increases the concentration ratio of metal ions, with the concentration of metal ions in the concentrate reaching more than 56 g / L.

[0033] 4. During the desorption process, the water entering the metal ion adsorption chamber is the system's produced water, without introducing an additional water source, making it more environmentally friendly. Attached Figure Description

[0034] Figure 1 This is a system diagram of the recycling device of the present invention;

[0035] Figure 2 yes Figure 1 A schematic diagram of the structure of the metal ion enrichment component described herein. Detailed Implementation

[0036] The technical solutions provided by the present invention will be described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0037] like Figures 1-2The metal ion recovery device in wastewater of the present application is mainly used for recovering copper ions in PCB wastewater, nickel ions and copper ions in electroplating wastewater and other heavy metal ions. The device comprises a metal ion enrichment assembly 3. One side of the metal ion enrichment assembly is provided with a cathode electrode plate 3-1, and the other side is provided with an anode electrode plate 3-9. A plurality of groups of repeated units of cation membrane 3-3, metal ion adsorption compartment 3-4, anion membrane 3-5 and metal ion enrichment chamber 3-6 are arranged between the cathode electrode plate 3-1 and the anode electrode plate 3-9. The cathode electrode plate 3-1 and the cation membrane 3-3 are separated into a cathode compartment 3-2. The anode electrode plate 3-9 and the anion membrane 3-7 are separated into an anode compartment 3-8. The metal ion selective resin 3-10 is filled in the metal ion adsorption compartment 3-4. The bottom of the metal ion adsorption compartment 3-4 in each repeated unit is connected to a wastewater buffer tank 1 through a pipeline, and the top is connected to a metal ion concentration tank 5 and a water production tank 4 through a pipeline. The anode compartment 3-9 is connected to an anode circulation tank 9 through a circulation pipeline, and the cathode compartment 3-1 is connected to a cathode circulation tank 7 through a circulation pipeline. The bottom and the top of the metal ion enrichment chamber in each repeated unit are respectively connected to the metal ion concentration tank 5 through a pipeline. The water production tank 4 and the metal ion concentration tank 5 are connected through a pipeline, and the water production tank 4 and the wastewater buffer tank 1 are connected through a pipeline. A wastewater lifting pump 2 and an electroplating wastewater inlet valve 13 are arranged on the outlet pipeline of the wastewater buffer tank 1. An anode circulation pump 10 is arranged on the outlet pipeline of the anode circulation tank 9, and a cathode circulation pump 8 is arranged on the outlet pipeline of the cathode circulation tank 7. A water production tank inlet valve 11 and a metal ion concentration inlet valve 12 are respectively arranged on the connecting pipeline between the water production tank 4 and the metal ion concentration tank 5. A concentrated regeneration inlet valve 14 and a water production lifting pump 15 are arranged on the connecting pipeline between the water production tank 4 and the wastewater buffer tank 1. A metal ion concentration lifting pump 6 is arranged on the connecting pipeline between the metal ion concentration tank 5 and the repeated unit.

[0038] The method for recovering metal ions in wastewater by using the above-mentioned metal ion recovery device in wastewater comprises the following steps:

[0039] Metal ion adsorption process: open the wastewater inlet valve 13, close the concentrated regeneration inlet valve 14, the wastewater 1 stored in the wastewater buffer tank is lifted into the metal ion adsorption compartment 3-4 from the bottom of the metal ion enrichment assembly 3 through the wastewater lifting pump 2, the wastewater contacts the metal ion selective resin 3-10 filled in the metal ion adsorption compartment 3-4, the metal ions in the wastewater are exchanged and adsorbed by the resin, the resin releases sodium, hydrogen ions and the like into the wastewater, and the wastewater from which the metal ions are removed flows out from the top of the metal ion enrichment assembly 3 after being collected through the pipeline, when the liquid level of the metal ion concentration tank 5 is lower than the set value, open the metal ion concentration tank inlet automatic valve 11, close the water tank inlet valve 12, the wastewater enters the metal ion concentration tank 5, and the water required for metal ion concentration is stored, when the liquid level of the metal ion concentration tank 5 is higher than the set value, close the metal ion concentration tank inlet valve 11, open the water tank inlet valve 12, the wastewater from which the metal ions are removed enters the water tank 4, and as qualified water, enters the next stage of treatment device.

[0040] Metal ion desorption enrichment process: when the metal ion selective resin 3-10 filled in the metal ion adsorption compartment 3-4 is saturated with adsorbed metal ions, the wastewater inlet valve 13 is closed, the concentrated regeneration inlet valve 14 is opened, the metal ion concentration tank inlet valve 11 is closed, the product water tank inlet valve 12 is opened, the water stored in the metal ion concentration tank 5 is lifted by the metal ion concentration tank lifting pump 6 and then enters the metal ion enrichment compartment 3-6 from the bottom of the metal ion enrichment assembly 3, and flows back to the metal ion concentration tank 5, and the product water is lifted by the product water lifting pump 15 and then enters the metal ion adsorption compartment 3-4 from the bottom of the metal ion enrichment assembly 3, and flows back to the product water tank 4; at the same time, the cathode circulating pump 8 is started to lift the cathode liquid (3% sodium chloride solution) stored in the cathode circulating tank 7, and the anode circulating pump 10 is started to lift the anode liquid (3% sodium sulfate solution) stored in the anode circulating tank 9, which respectively enter the cathode compartment 3-2 and the anode compartment 3-8 from the bottom of the metal ion enrichment assembly 3, and the effluent flows back to the cathode circulating tank 7 and the anode circulating tank 9, respectively, and a direct current voltage is applied between the cathode and anode electrode plates of the metal ion enrichment assembly 3, the metal ions adsorbed by the metal ion selective resin 3-10 move towards the cathode under the action of the electric field, and since the cation membrane 3-3 has selective permeability, the metal ions can pass through the cation membrane 3-3 smoothly and enter the metal ion enrichment compartment 3-6, and since the anion membrane 3-5 blocks the metal ions entering the metal ion enrichment compartment 3-6 from further migrating forward, the metal ions are blocked in the metal ion enrichment compartment 3-6, forming enrichment, so that the metal ion concentration in the concentrated water reaches 56 g / L or more. The cation vacancies of the resin generated by the migration of the metal ions are replaced by sodium ions and hydrogen ions in the product water entering the metal ion adsorption compartment 3-4, realizing the desorption and regeneration of the resin. The anions in the metal ion adsorption compartment 3-4 pass through the anion membrane 3-5 into the metal ion enrichment compartment 3-6 under the action of the electric field, realizing the balance of cations and anions. After the desorption of the system is completed, the metal ion adsorption stage is entered.

[0041] It should be noted that the above content only illustrates the technical idea of the present application, and cannot limit the protection scope of the present application. For ordinary skilled persons in the technical field, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements fall within the protection scope of the claims of the present application.

Claims

1. A device for recovering metal ions in wastewater, characterized by comprising: The metal ion enrichment assembly comprises a cathode electrode plate arranged on one side, an anode electrode plate arranged on the other side, and a plurality of sets of repeated units of cation membrane, metal ion adsorption compartment, anion membrane and metal ion enrichment chamber arranged between the cathode electrode plate and the anode electrode plate. The metal ion adsorption compartment is filled with metal ion selective resin, the bottom of the metal ion adsorption compartment in each repeated unit is connected to a wastewater buffer tank through a pipeline, the top is connected to a metal ion concentration tank and a water production tank through a pipeline, the anode compartment is connected to an anode circulation tank through a circulation pipeline, and the cathode compartment is connected to a cathode circulation tank through a circulation pipeline.

2. The apparatus according to claim 1, wherein A wastewater lifting pump and an electroplating wastewater inlet valve are arranged on the outlet pipeline of the wastewater buffer tank.

3. The apparatus according to claim 1, wherein An anode circulation pump is arranged on the outlet pipeline of the anode circulation tank.

4. The apparatus according to claim 1, wherein A cathode circulation pump is arranged on the outlet pipeline of the cathode circulation tank.

5. The apparatus according to claim 1, wherein A water production tank inlet valve and a metal ion concentration inlet valve are arranged on the connecting pipelines of the water production tank and the metal ion concentration tank, respectively.

6. The apparatus according to claim 1, wherein A concentrated regeneration inlet valve and a water production lifting pump are arranged on the connecting pipelines of the water production tank and the wastewater buffer tank.

7. The apparatus according to claim 1, wherein A metal ion concentration lifting pump is arranged on the connecting pipelines of the metal ion concentration tank and the repeated units.

8. A method for recovering metal ions from wastewater using the apparatus for recovering metal ions from wastewater according to any one of claims 1 to 7, characterized by, The method comprises a metal ion adsorption process and a metal ion desorption enrichment process, and specifically: The metal ion adsorption process: open the wastewater inlet valve, close the concentrated regeneration inlet valve, the wastewater stored in the wastewater buffer tank is lifted from the bottom of the metal ion enrichment assembly into the metal ion adsorption compartment through the wastewater lifting pump, the wastewater contacts the metal ion selective resin filled in the metal ion adsorption compartment, the metal ions in the wastewater are exchanged and adsorbed by the resin, the wastewater from which the metal ions are removed is collected through the pipeline and then flows out from the top of the metal ion enrichment assembly, when the liquid level of the metal ion concentration tank is lower than the set value, open the metal ion concentration tank inlet automatic valve, close the water production tank inlet valve, the wastewater enters the metal ion concentration tank, and the water required for metal ion concentration is stored, when the liquid level of the metal ion concentration tank is higher than the set value, close the metal ion concentration tank inlet automatic valve, open the water production tank inlet valve, the wastewater from which the metal ions are removed enters the water production tank, and the qualified water enters the next stage of treatment device. The nickel ion desorption enrichment process: when the metal ion selective resin filled in the metal ion adsorption compartment adsorbs the metal ions to saturation, the wastewater inlet valve is closed, the concentrated regeneration inlet valve is opened, the metal ion concentration tank inlet automatic valve is closed, the product water tank inlet valve is opened, the water stored in the metal ion concentration tank is lifted by the metal ion concentration tank lifting pump and then enters the metal ion enrichment compartment from the bottom of the metal ion enrichment assembly and flows back to the metal ion concentration tank, and the product water is lifted by the product water lifting pump and then enters the metal ion adsorption compartment from the bottom of the metal ion enrichment assembly and flows back to the product water tank; at the same time, the cathode circulating pump is started to lift the catholyte stored in the cathode circulating tank, the anode circulating pump is started to lift the anolyte stored in the anode circulating tank, and the two enter the cathode compartment and the anode compartment from the bottom of the metal ion enrichment assembly, respectively, and the effluent flows back to the cathode circulating tank and the anode circulating tank, respectively; at the same time, a direct current voltage is applied between the cathode and anode electrode plates of the metal ion enrichment assembly, the metal ions adsorbed by the metal ion selective resin move towards the cathode under the action of the electric field, the metal ions can pass through the cation membrane smoothly due to the selective permeability of the cation membrane, and the metal ions entering the metal ion enrichment compartment cannot further migrate forward and are blocked in the metal ion enrichment compartment due to the blocking of the anion membrane, thereby forming enrichment and making the metal ion concentration in the concentrated water reach 56 g / L or more; the cation vacancies of the resin generated by the migration of the metal ions are replaced by sodium ions and hydrogen ions in the product water entering the metal ion adsorption compartment, thereby realizing the desorption and regeneration of the resin; the anions in the metal ion adsorption compartment pass through the anion membrane into the metal ion enrichment compartment under the action of the electric field, thereby realizing the balance of the cations and anions, and the system desorption is completed, and the system enters the metal ion adsorption stage.

9. The method of recovering metal ions from wastewater according to claim 8, wherein, The catholyte in the cathode circulating tank is a sodium chloride solution with a mass percentage concentration of 3%.

10. The method of recovering metal ions from wastewater according to claim 8, wherein, The anolyte in the anode circulating tank is a sodium sulfate solution with a mass percentage concentration of 3%.

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