Nickel-containing wastewater treatment device and nickel-containing wastewater treatment method

Abstract

The present application provides a nickel-containing wastewater treatment device and a nickel-containing wastewater treatment method. The nickel-containing wastewater treatment device includes a complex-breaking pretreatment system connected in sequence to perform complex-breaking pretreatment on the nickel-containing wastewater; a pretreatment system including a Fenton oxidation system and an ozone catalytic oxidation system connected in sequence; a deep treatment system including ion exchange resin; and a nickel recovery system including a resin desorption system, an extraction system, and a distillation system arranged in sequence. The nickel-containing wastewater treatment device of the present application uses the pretreatment system and the deep treatment system for treatment to achieve the dual goals of meeting the wastewater standards and enriching nickel ions, without introducing other pollutants at the same time; and then recovers nickel resources through the nickel recovery system, and no solid waste is generated during the recovery process.

Description

Technical Field

[0001] The present application relates to the field of wastewater treatment, and in particular, to a nickel-containing wastewater treatment device and a nickel-containing wastewater treatment method. Background Art

[0002] Electroplating is to deposit a required coating on the surface of a product through an electrochemical method to achieve protection, modification of the surface of a metal or non-metal, and endow the product with new properties, etc. In recent years, the electroplating industry in China has developed rapidly. As the main method for metal surface modification, nickel plating will generate a large amount of nickel-containing wastewater during the process. According to incomplete statistics, 4 billion m 3 of electroplating wastewater is discharged every year, and 50% of it does not meet the discharge standard. The pollutants in electroplating wastewater are difficult to be biodegradable and are easy to accumulate in organisms, which will pose a serious threat to the environment and humans if discharged into the environment. The commonly used methods for treating nickel-containing wastewater generally are traditional chemical precipitation methods mainly based on hydroxides and sulfides, which are mainly applicable to the treatment of free nickel, but it is very difficult to remove complexed nickel. Other methods such as electrolysis, ion exchange, adsorption, and advanced oxidation-reduction methods can ensure that the total nickel in the effluent meets the standard, but they generally have high costs, long reaction times, and are prone to cause secondary pollution, which limits their practical applications. With the increasingly strict wastewater discharge standards, it is required that the residual Ni2+ concentration in the treated nickel-containing electroplating wastewater is lower than the special discharge limit of 0.1 mg / L in the "Discharge Standard of Pollutants for Electroplating (GB21900-2008)". Therefore, it is necessary to develop a more stable and effective method for deep treatment of nickel-containing wastewater.

[0003] The recovery of nickel resources from electroplating wastewater is mainly carried out by turning nickel-containing wastewater into nickel-containing sludge, online recovery, or resin adsorption, etc. The recovery rate is relatively low and the purity of the recovered nickel salt is poor, making it difficult to be sold as a product. How to improve the recovery rate and purity of nickel salt is still a technical problem that needs to be solved urgently.

[0004] In view of this, it is necessary to provide an improved nickel-containing wastewater treatment device and a nickel-containing wastewater treatment method to solve the above technical problems. Summary of the Invention

[0005] The purpose of the present application is to provide a nickel-containing wastewater treatment device and a nickel-containing wastewater treatment method that can at least solve one of the above problems.

[0006] To achieve the above application purpose, the present application adopts the following technical solutions:

[0007] A nickel-containing wastewater treatment device includes, connected in sequence

[0008] a complex-breaking pretreatment system for performing complex-breaking pretreatment on nickel-containing wastewater;

[0009] The pretreatment system includes a Fenton oxidation system and an ozone catalytic oxidation system connected in sequence;

[0010] The advanced treatment system includes ion exchange resins;

[0011] And the nickel recovery system includes a resin desorption system, an extraction system, and a distillation system arranged in sequence.

[0012] Furthermore, the ion exchange resin is a macroporous styrene series chelating ion exchange resin.

[0013] To achieve the above application purpose, the present application also adopts the following technical solutions:

[0014] A method for treating nickel-containing wastewater includes:

[0015] S1 Breaking the complex and pretreatment: Adding an alkali solution to perform breaking the complex pretreatment on the nickel-containing wastewater, and the supernatant after the breaking the complex pretreatment is used as the pretreatment;

[0016] S2 Pretreatment: The pretreatment influent is sequentially subjected to pH adjustment, Fenton oxidation, and ozone catalytic oxidation treatment;

[0017] S3 Advanced treatment: Enriching nickel through ion resins;

[0018] S4 Nickel recovery: Desorbing the resin enriched with nickel to obtain a nickel-containing resin regeneration solution, extracting the nickel-containing resin regeneration solution, and distilling the extract.

[0019] Furthermore, step S1 specifically includes adjusting the pH to 10 - 11 with a 30% sodium hydroxide solution to play a role in partially breaking the complex.

[0020] Furthermore, step S1 also includes adding an appropriate amount of polyacrylamide for flocculation precipitation after the breaking the complex pretreatment, standing, and taking the supernatant as the pretreatment influent.

[0021] Furthermore, step S2 specifically includes:

[0022] S21 pH adjustment: Adjusting the wastewater parameters to a pH value of 3.0 - 4.0 through an acid;

[0023] S22 Fenton oxidation: The dosage of 30% H2O2 is about 1.0 ml / L, and the dosage of Fe 2+ is about 150 mg / L, and reacting for the first predetermined time;

[0024] S23 Ozone catalytic oxidation: The wastewater after Fenton oxidation is directly subjected to ozone catalysis, the ozone dosage is 300 - 400 mg / L, and reacting for the second predetermined time.

[0025] Furthermore, the ratio of the first predetermined time to the second predetermined time is 1:3.

[0026] Further, in step S3, the pH value ranges from 5 to 6, and the ion exchange resin is a macroporous styrene series chelating ion exchange resin.

[0027] Further, in step S4, the resin desorption process is as follows: The ion exchange resin enriched with nickel is desorbed and regenerated using an acid solution to obtain a nickel-containing resin regeneration solution.

[0028] Further, in step S4, the extraction process is specifically as follows:

[0029] First, adjust the pH value of the nickel-containing resin regeneration solution to about 4.5, then add an extractant suitable for an acidic medium for extraction. The volume ratio of the extractant to the wastewater is 1:1, the extraction time is 2 - 4 minutes, and after extraction, let it stand for layer separation;

[0030] Then, separate the nickel ions from the nickel-rich organic phase using sulfuric acid, that is, back-extraction. The volume ratio of the organic phase to sulfuric acid is 1:2, and let it stand for layer separation.

[0031] Further, the extractant is a mixture of di-(2-ethylhexyl)-phosphoric acid and kerosene, and the volume ratio of di-(2-ethylhexyl)-phosphoric acid to kerosene is 15%.

[0032] The beneficial effects of the present application are as follows: The nickel-containing wastewater treatment device of the present application uses a pretreatment system and a deep treatment system for treatment, achieving the dual goals of meeting the wastewater standards and enriching nickel ions, without introducing other pollutants at the same time; then, the nickel recovery system is used to recover nickel resources, and no solid waste is generated during the recovery process. Description of the Drawings

[0033] Figure 1 is a schematic structural diagram of the nickel-containing wastewater treatment device of the present invention. Specific Embodiments

[0034] The following will describe the present application in detail in conjunction with the specific embodiments shown in the drawings. However, these embodiments do not limit the present application, and any structural, method, or functional transformation made by those of ordinary skill in the art based on these embodiments is included within the protection scope of the present application.

[0035] In each of the drawings of the present application, for the convenience of illustration, the sizes of some structures or parts are exaggerated relative to other structures or parts. Therefore, it is only used to illustrate the basic structure of the subject matter of the present application.

[0036] As Figure 1 shown, the nickel-containing wastewater treatment device of the preferred embodiment of the present invention includes a complex-breaking pretreatment system, a pretreatment system, a deep treatment system, and a nickel recovery system connected in sequence.

[0037] The "sequential connection" in this text refers to being set up in sequence according to the wastewater treatment process, and the adjacent two systems can be directly connected through pipelines, facilitating the automatic flow of wastewater to the next treatment system, or can be indirectly connected, that is, there is no pipeline between the two, and the wastewater is transferred from the previous treatment system to the next treatment system through manual intervention.

[0038] The nickel-containing wastewater sequentially passes through a complex-breaking pretreatment system, a pretreatment system, a deep treatment system, and a nickel recovery system to achieve the dual goals of meeting the wastewater treatment standards and enriching nickel ions.

[0039] Among them, in the complex-breaking pretreatment system, complex-breaking treatment is carried out by adding alkali liquor to the wastewater, reducing the dosage of chemical reagents in the subsequent pretreatment system, and improving the treatment effect of the subsequent processes.

[0040] The pretreatment system includes a Fenton treatment system and an ozone catalytic oxidation system; the Fenton treatment system can decompose some organic pollutants in the wastewater, which can not only achieve the effect of oxidation and complex-breaking, converting the complexed metal nickel into a free state, but also oxidize the organic matter in the wastewater, etc. The ozone catalytic oxidation system can further oxidize the organic matter, reduce the COD of the wastewater, and at the same time can remove some metal ions, such as iron, etc.

[0041] The deep treatment system contains ion exchange resins for adsorbing and enriching nickel. Preferably, it contains two or more stages of ion exchange resins connected in series. The ion exchange resin is preferably a macroporous cation exchange resin with the most ideal adsorption and removal effect on nickel ions in the wastewater, such as a macroporous styrene series chelating ion exchange resin.

[0042] The nickel recovery system includes a resin desorption system, an extraction system, and a distillation system arranged in sequence. The extraction system is used to extract nickel and extract and separate other impurity metals. In this application, a multi-stage extraction system with two or more stages is preferably selected, and the extraction rate is high. The distillation system is a vacuum distillation system.

[0043] The method for treating nickel-containing wastewater of the present invention includes the following steps:

[0044] S1 Complex-breaking pretreatment: Add alkali liquor to carry out complex-breaking treatment on the nickel-containing wastewater, and the supernatant after complex-breaking pretreatment is used as the pretreatment. Generally, the electroplating nickel-containing wastewater is acidic, and the pH is first adjusted through the complex-breaking pretreatment system. For example, the pH is adjusted to 10-10.5 with 30% sodium hydroxide solution to play a role in partial complex-breaking.

[0045] Furthermore, after complex-breaking pretreatment, an appropriate amount of polyacrylamide (PAM) is added for flocculation precipitation. After standing, the supernatant is taken and used as the pretreatment influent.

[0046] Pre-treatment in S2: The influent water for pre-treatment is successively subjected to pH adjustment, Fenton oxidation, and ozone catalytic oxidation treatment.

[0047] Step S2 specifically includes: S21 pH adjustment, adjusting the wastewater parameters to a pH value of 3.0 - 4.0 through an acid; for example, adjusting the pH value of the wastewater to about 3.0 through sulfuric acid; S22 Fenton oxidation, the dosage of 30% H2O2 is about 1.0 ml / L, and the dosage of Fe 2+ is about 150 mg / L, and reacting for a first predetermined time; S23 ozone catalytic oxidation, directly subjecting the wastewater after Fenton oxidation to ozone catalysis, with an ozone dosage of 300 - 400 mg / L and reacting for a second predetermined time. The ratio of the first predetermined time to the second predetermined time is 1:3, and the removal rate of nickel concentration in the effluent of the pre-treatment system can reach 60% - 70%.

[0048] Deep treatment in S3: Enriching nickel through ion resin, that is, adopting the method of resin ion exchange to deeply treat the nickel-containing wastewater after pre-treatment to achieve the dual goals of meeting the wastewater discharge standards and nickel ion enrichment, while minimizing the introduction of other pollutants.

[0049] Preferably, two or more series-connected resin adsorption columns are used for adsorption to improve the adsorption effect.

[0050] Specifically, the ion exchange resin is preferably a macroporous cation exchange resin with the most ideal adsorption and removal effect on nickel ions in the wastewater, such as a macroporous styrene series chelating ion exchange resin. The best treatment parameters are that the pH value range is 5 - 6, and the removal rate of nickel continuously increases with the increase in the dosage of the resin, and finally the removal rate of nickel reaches about 90%.

[0051] Nickel recovery in S4: Desorbing the resin enriched with nickel to obtain a nickel-containing resin regeneration solution, extracting the nickel-containing resin regeneration solution, and distilling the extraction solution.

[0052] Specifically, the process of resin desorption is as follows: Using an acid solution to desorb and regenerate the ion exchange resin enriched with nickel to obtain a nickel-containing resin regeneration solution, the nickel ion concentration of which reaches more than several tens of g / L and has the value of recovery. For example, using a sulfuric acid solution with a mass fraction of 3% to regenerate and desorb the ion exchange resin enriched with nickel that has been adsorbed and saturated, and the obtained nickel resin regeneration solution has a nickel ion concentration of 20 g / L.

[0053] The extraction process is as follows: First, adjust the pH value of the nickel-containing resin regeneration liquid to about 4.5, and then add an extractant suitable for acidic media for extraction. The volume ratio of the extractant to the wastewater is 1:1, the extraction time is 2 - 4 minutes, and after extraction, let it stand for layering. The extractant is a mixture of di-(2-ethylhexyl)-phosphoric acid (P204) and kerosene, and the volume ratio of P204 to kerosene is 15%. At room temperature, after 3-stage extraction, the nickel extraction rate reaches over 90%, for example, about 95%.

[0054] Then, use sulfuric acid to separate nickel ions from the nickel-rich organic phase, that is, back-extraction. The volume ratio of the organic phase to sulfuric acid is 1:2, and let it stand for layering. Extraction and separation are to remove other impurity ions in the nickel-containing resin regeneration liquid, such as a small amount of metal impurities like iron and zinc, etc., to obtain a nickel-containing solution with higher purity.

[0055] The distillation process is as follows: Carry out the crystallization recovery of nickel salt by means of vacuum distillation to realize the recovery of industrial-grade nickel salt resources. After extraction, the nickel salt purification liquid evaporates and concentrates the mixed liquid to 3 times under a suitable negative pressure, and then cools and crystallizes to obtain nickel salt with a certain purity. In the present invention, the heavy metal nickel ions regarded as waste in the wastewater are transformed into crystalline nickel salt products, recycled and reused, avoiding resource waste and reducing the discharge of hazardous waste, with good environmental and economic benefits.

[0056] In summary, this application uses a pretreatment system and a deep treatment system for treatment to achieve the dual goals of meeting the wastewater discharge standard and enriching nickel ions, without introducing other pollutants at the same time; then, through the nickel recovery system, nickel resources are recovered, and no solid waste is generated during the recovery process.

[0057] It should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0058] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of this application, and they are not used to limit the protection scope of this application. Any equivalent embodiments or changes made without departing from the technical spirit of this application should be included in the protection scope of this application.

Claims

1. A nickel-containing wastewater treatment device, characterized in that, including a sequentially connected complex-breaking pretreatment system for performing complex-breaking pretreatment on nickel-containing wastewater; pretreatment system including a sequentially connected Fenton oxidation system and an ozone catalytic oxidation system; advanced treatment system including ion exchange resins, where the ion exchange resins are macroporous styrene series chelating ion exchange resins; and nickel recovery system including a sequentially arranged resin desorption system, extraction system, and distillation system.

2. A method for treating nickel-containing wastewater, comprising: S1 Complex-breaking pretreatment: adding an alkali solution to perform complex-breaking pretreatment on the nickel-containing wastewater, and subjecting the supernatant after the complex-breaking pretreatment to pretreatment; S2 Pretreatment: sequentially performing pH adjustment, Fenton oxidation, and ozone catalytic oxidation on the pretreatment influent; S3 Advanced treatment: enriching nickel through ion exchange resins, where the ion exchange resins are macroporous styrene series chelating ion exchange resins and the pH value ranges from 5 to 6; S4 Nickel recovery: desorbing the resin enriched with nickel to obtain a nickel-containing resin regeneration solution, extracting the nickel-containing resin regeneration solution, and distilling the extract.

3. The nickel-containing wastewater treatment method according to claim 2, wherein: Step S1 specifically includes adjusting the pH to 10 - 11 with a 30% sodium hydroxide solution to play a role in partial complex-breaking.

4. The nickel-containing wastewater treatment method according to claim 3, characterized in that: Step S1 further includes adding an appropriate amount of polyacrylamide for flocculation precipitation after the complex-breaking pretreatment, standing still, and taking the supernatant as the pretreatment influent.

5. The nickel-containing wastewater treatment method according to claim 2, wherein: Step S2 specifically includes: S21. pH adjustment: adjusting the wastewater parameters to a pH value of 3.0 - 4.0 through an acid; S22, Fenton oxidation, the dosage of 30% H2O2 is about 1.0 ml / L, and the dosage of Fe 2+ is about 150 mg / L, reacting for the first predetermined time; S23. Ozone catalytic oxidation: directly performing ozone catalysis on the wastewater after Fenton oxidation, with an ozone dosage of 300 - 400 mg / L for a second predetermined time.

6. The nickel-containing wastewater treatment method according to claim 5, wherein: Wherein the ratio of the first predetermined time to the second predetermined time is 1:

3.

7. The nickel-containing wastewater treatment method according to claim 2, wherein: In step S4, the process of resin desorption is: using an acid solution to desorb and regenerate the ion exchange resin enriched with nickel to obtain a nickel-containing resin regeneration solution.

8. The nickel-containing wastewater treatment method according to claim 2, wherein: In step S4, the extraction process specifically is: first adjusting the pH value of the nickel-containing resin regeneration solution to about 4.5, then adding an extractant suitable for an acidic medium for extraction, with the volume ratio of the extractant to the wastewater being 1:1, an extraction time of 2 - 4 min, and standing still for layering after extraction; then separating nickel ions from the nickel-rich organic phase with sulfuric acid, i.e., back extraction, with the volume ratio of the organic phase to sulfuric acid being 1:2, and standing still for layering.

9. The method for treating nickel-containing wastewater according to claim 8, wherein: The extractant is a mixture of di-(2-ethylhexyl)-phosphoric acid and kerosene, and the volume ratio of di-(2-ethylhexyl)-phosphoric acid to kerosene is 15%.

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