Zero-discharge treatment process for electronickelling wastewater

Abstract

The invention provides a zero-discharge treatment process for nickel electroplating wastewater. The zero-discharge treatment process comprises the following steps: S1, carrying out physicochemical treatment on the nickel electroplating wastewater to enable metal ions to form precipitates; s2, removing slag through a fine filtration system; s3, performing reverse osmosis treatment in a membrane treatment system, and recovering clear liquid; s4, concentrated liquor obtained after reverse osmosis treatment enters an electrodialysis system to be concentrated; and S5, carrying out evaporation curing treatment on the concentrated solution to realize zero discharge of wastewater. According to the zero-discharge treatment process for the electronickelling wastewater, the treated clear liquid can be recycled, the discharged waste is in a solid state, and zero discharge of the electronickelling wastewater is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and particularly relates to a zero-discharge treatment process for electroplating nickel wastewater. Background Art

[0002] Electroplating is a technology that uses the principle of electrolysis to deposit metal or alloy on the surface of a workpiece to form a uniform, dense, and well-bonded metal coating, which can play roles such as preventing corrosion, improving wear resistance, conductivity, and aesthetics. At present, the plating materials used in electroplating are mainly nickel, and its plating solution mainly includes nickel sulfate, nickel chloride, boric acid, nickel sulfamate, sodium sulfate, sodium dodecyl sulfate, and many aromatic compounds, etc. Nickel belongs to the first-class pollutants. If nickel-containing wastewater is discharged into the environment without reaching the standard, it will accumulate in the soil and, through the food chain, eventually accumulate in animals and plants. After nickel enters the human body, it will cause skin inflammation, such as rashes, papules, follicular dermatitis, or even ulcers in mild cases; in severe cases, it will damage the central nervous system, cause organ lesions, and endanger life. For the discharge of nickel pollutants, the national standard "GB 21900-2008 Discharge Standard of Pollutants for Electroplating" stipulates that the mass concentration of nickel is less than 0.1 mg / L. In some areas with fragile ecology and dense population, etc., even "zero discharge" is required, and the traditional oxidation-hydroxide precipitation method can no longer meet the requirements. Summary of the Invention

[0003] The purpose of the present invention is to fill the gaps in the above fields and provide a zero-discharge treatment process for electroplating nickel wastewater that can realize the recycling of wastewater and the discharge products are all solids.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A zero-discharge treatment process for electroplating nickel wastewater, comprising the following steps:

[0006] S1: The electroplating nickel wastewater is subjected to physical and chemical treatment to form precipitates of metal ions;

[0007] S2: Remove slag through a fine filtration system to remove large-particle-size soil and precipitation slag particles;

[0008] S3: Enter the membrane treatment system for reverse osmosis treatment. The clear liquid is recovered for reuse, and the salt ions in the wastewater enter the concentrated liquid;

[0009] S4: The concentrated liquid after reverse osmosis treatment enters the electrodialysis system. Under the action of an electric field, the concentrated liquid is further concentrated to separate water;

[0010] S5: The concentrated liquid after the concentrated treatment by the electrodialysis system is subjected to evaporation and solidification treatment to achieve zero discharge of wastewater.

[0011] As a preferred embodiment of the present invention, in the step S1, the method for forming a precipitate of metal ions is as follows: the electroplating nickel wastewater first enters an alkalization tank, and alkali is added to adjust the pH to 9-11 to form a precipitate of nickel ions, and then it enters a sedimentation tank for sedimentation and collection.

[0012] Further, in the step S1, the residence time of the electroplating nickel wastewater in the sedimentation tank is 2-4 hours, so that the nickel ion precipitate can be fully sedimented.

[0013] As another preferred embodiment of the present invention, the method for slag removal in the step S2 is as follows: first, mud-water separation is carried out by a mud removal machine, and after the sludge is discharged, the clear liquid enters a fine filter for filtration and slag removal, which improves the slag removal efficiency and reduces the probability of clogging of the fine filter.

[0014] As another preferred embodiment of the present invention, before the step S3, the clear liquid after slag removal by the fine filtration system needs to be adjusted to pH 6-8.

[0015] As another preferred embodiment of the present invention, the conductivity of the clear liquid after reverse osmosis treatment by the membrane treatment system in the step S3 is ≤1 us / cm, and the total organic carbon TOC is ≤0.1 mg / L, which can meet the standard for recycling.

[0016] As another preferred embodiment of the present invention, the salt concentration of the concentrated liquid after concentration treatment by the electrodialysis system in the step S4 is ≥15%.

[0017] As another preferred embodiment of the present invention, the clear liquid after concentration treatment by the electrodialysis system in the step S4 enters the membrane treatment system again for reverse osmosis treatment to further purify the water in the clear liquid.

[0018] As another preferred embodiment of the present invention, in the step S5, the evaporation and solidification treatment is as follows: first, salts are precipitated by a low-temperature evaporation system, the condensed water is recycled, and the salts are formed into solid waste through a solidification system.

[0019] Advantages of the present invention:

[0020] Compared with the prior art, the zero-discharge treatment system for electroplating nickel wastewater provided by the present invention sequentially performs physical and chemical treatment, fine filtration and slag removal, desalination and impurity removal, and evaporation and solidification treatment on the electroplating nickel wastewater. The discharged mud, residue, and solid waste are all in solid form, and the clear liquid after treatment by the membrane treatment system and the condensed water after treatment by the low-temperature evaporation system can both be recycled, realizing the "zero discharge" of electroplating nickel wastewater. Description of the drawings

[0021] Figure 1 It is a schematic diagram of the treatment process of the present invention;

[0022] Figure 2It is a schematic structural diagram of an embodiment of the present invention, where: 1 - Wastewater quality separation and diversion system; 2 - Alkalization reaction tank; 21 - Alkalization tank; 22 - Sedimentation tank; 3 - Mud removal machine; 4 - Fine filter; 5 - Neutralization tank; 6 - Membrane treatment system; 7 - Electrodialysis system; 8 - Low-temperature evaporation system; 9 - Solidification system. Specific embodiments

[0023] To better understand the present invention, the following further describes the specific embodiments of the present invention in detail with reference to the accompanying drawings.

[0024] See the appendix Figure 1-2 A zero-discharge treatment process for electroplating nickel wastewater provided by the present invention includes:

[0025] S1: The electroplating nickel wastewater is subjected to physical and chemical treatment to form precipitates of metal ions. The electroplating nickel wastewater collected by the wastewater quality separation and diversion system 1 enters the alkalization tank 21 through a pipeline, and sodium hydroxide or ammonium hydroxide is added to adjust the pH value of the wastewater to 9 - 11, so that nickel ions form precipitates, and then it enters the sedimentation tank 22 and stays for 4 hours to make the nickel ion precipitates settle sufficiently;

[0026] S2: Remove slag through the fine filtration system. After physical and chemical treatment, it enters the mud removal machine 3 for mud-water separation. After removing large-particle-size mud, it then enters the fine filter 4 to filter small-particle-size precipitates and remove residues;

[0027] S3: The clear liquid filtered by the fine filter 4 adjusts the pH value to 6 - 8 through the neutralization tank 5, and then enters the membrane treatment system 6 for reverse osmosis treatment. The conductivity of the clear liquid ≤ 1 us / cm, and the total organic carbon TOC ≤ 0.1 mg / L, and it is recycled and reused. The concentrated liquid enters the electrodialysis system 7 for further concentration;

[0028] S4: The concentrated liquid after reverse osmosis treatment enters the electrodialysis system 7, and under the action of an electric field, the concentrated liquid is further concentrated to a salt concentration ≥ 15%, and the clear liquid enters the membrane treatment system 6 for purification again;

[0029] S5: The concentrated concentrated liquid is subjected to evaporation and solidification treatment to achieve zero discharge of wastewater. The concentrated liquid after concentration by the electrodialysis system 7 enters the low-temperature evaporation system 8, the condensed water obtained by evaporation is recycled and reused, and the waste after evaporation enters the solidification system 9 for solid treatment.

[0030] In the zero-discharge treatment process for electroplating nickel wastewater provided by the present invention, the mud treated by the mud removal machine 3, the residues treated by the fine filter 4, and the solid waste treated by the solidification system 9 are all solids. The clear liquid treated by the membrane treatment system 6 and the condensed water treated by the low-temperature evaporation system 8 can be recycled and reused, realizing the "zero discharge" of electroplating nickel wastewater.

[0031] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A zero-discharge treatment process for electroplating nickel wastewater, characterized in that, It includes the following steps: S1: The electroplating nickel wastewater undergoes physical and chemical treatment to form precipitates of metal ions; S2: Remove residues through a fine filtration system; S3: Enter the membrane treatment system for reverse osmosis treatment, and the clarified liquid is recycled; S4: The concentrated liquid after reverse osmosis treatment enters the electrodialysis system for concentration; S5: The concentrated liquid after concentration undergoes evaporation and solidification treatment to achieve zero discharge of wastewater.

2. The zero-discharge treatment process for electroplating nickel wastewater according to claim 1, characterized in that, The method for forming precipitates of metal ions in step S1 is as follows: The electroplating nickel wastewater first enters the alkalization tank, and alkali is added to adjust the pH to 9 - 11 to form precipitates of nickel ions, and then it enters the sedimentation tank for sedimentation and collection.

3. The zero-discharge treatment process for electroplating nickel wastewater according to claim 2, characterized in that, In step S1, the residence time of the electroplating nickel wastewater in the sedimentation tank is 2 - 4 hours.

4. The zero - discharge treatment process for electroplating nickel wastewater according to claim 1, wherein, The method for removing residues in step S2 is as follows: First, the mud and water are separated by a mud remover, and after the sludge is discharged, the clarified liquid enters the fine filter for filtration to remove residues.

5. The zero-discharge treatment process for electroplating nickel wastewater according to claim 1, wherein, Before step S3, the clarified liquid after removing residues by the fine filtration system needs to be adjusted to pH 6 - 8.

6. The zero-discharge treatment process for electroplating nickel wastewater according to claim 1, wherein, In step S3, the conductivity of the clarified liquid after reverse osmosis treatment by the membrane treatment system is ≤1 us / cm, and the total organic carbon TOC is ≤0.1 mg / L.

7. The zero-discharge treatment process for electroplating nickel wastewater according to claim 1, characterized in that, In step S4, the salt concentration of the concentrated liquid after concentration treatment by the electrodialysis system is ≥15%.

8. The zero-discharge treatment process for electroplating nickel wastewater according to claim 1, characterized in that, In step S4, the clarified liquid after concentration treatment by the electrodialysis system enters the membrane treatment system again for reverse osmosis treatment.

9. The zero-discharge treatment process for electroplating nickel wastewater according to claim 1, characterized in that, In step S5, the evaporation and solidification treatment is to first precipitate salts through a low-temperature evaporation system, the condensed water is recycled, and the salts then form solid waste through the solidification system.

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