Recovery system for nickel-containing wastewater

Abstract

The invention discloses a nickel-containing wastewater recovery system, which belongs to the technical field of nickel-containing wastewater treatment, and comprises a physicochemical subsystem, a recycling subsystem and a sludge subsystem, the physicochemical subsystem comprises a first regulating tank, a second regulating tank, a first-stage reaction tank, a second-stage reaction tank, a coagulation reaction tank, a flocculation reaction tank and a sedimentation tank which are sequentially connected; the first regulating tank is used for carrying out average value and average quantity treatment on the nickel-containing wastewater; the recycling subsystem comprises a middle water tank, a quartz sand filter, an activated carbon filter, a filtered water tank, a reverse osmosis cartridge filter, a reverse osmosis device and a recycling water tank which are connected in sequence; the sludge subsystem comprises a sludge thickening tank, a sludge dewatering machine and a sludge drying machine which are connected in sequence. According to the method, efficient treatment of nickel-containing wastewater and effective recovery of nickel resources are achieved, an environment-friendly and economical wastewater treatment solution is provided for the electroplating industry, and the method has remarkable technical advantages and application value.

Description

Technical Field

[0001] The invention belongs to the technical field of nickel-containing wastewater treatment, and in particular relates to a nickel-containing wastewater recovery system. Background Art

[0002] Printed circuit boards (PCBs) are an indispensable core component of electronic devices and are widely used in consumer electronics, communication equipment, automotive electronics, industrial control and other fields. In the PCB manufacturing process, flexible printed circuit boards (FPCs) are particularly important in high-density integration and miniaturized devices due to their lightness and bendability. However, the production of FPCs involves a variety of chemical processes, among which nickel electroplating is one of the key steps, which is used to form a conductive layer on the surface of the circuit and enhance wear resistance and corrosion resistance. However, while the nickel electroplating process improves the performance of FPCs, it also brings serious environmental problems.

[0003] During the nickel electroplating process, a large amount of nickel-containing wastewater will be generated. If these nickel-containing wastewaters are discharged directly without proper treatment, they will cause serious harm to the ecological environment and human health. Nickel is a toxic heavy metal that is bioaccumulative and can enter the human body through the food chain, causing skin allergies, respiratory diseases and even cancer. The main sources of nickel in wastewater include the fact that the plating solution will become ineffective due to impurity accumulation and imbalance of components during use, and needs to be replaced regularly, resulting in high-concentration nickel-containing wastewater; the FPC after electroplating needs to go through multiple water washing processes to remove the residual plating solution on the surface, thereby generating low-concentration nickel-containing wastewater; the cleaning and maintenance of electroplating tanks, pipes and equipment will also generate nickel-containing wastewater.

[0004] The common ionic form of nickel in wastewater is Ni 2+ In the nickel plating solution, nickel salts (such as nickel sulfate, nickel chloride, etc.) dissolve and dissociate into Ni 2+ When wastewater is generated in the process of plating solution cleaning, these Ni 2+ Under acidic conditions, Ni 2+ It is relatively stable; however, as the pH value of the wastewater increases, it will combine with hydroxide ions to form nickel hydroxide precipitate.

[0005] Ni 2+ Coordinate with water molecules to form hydrated Ni 2+ , such as [Ni(H2O)6] 2+ This form of Ni 2+ Widely found in wastewater systems, its chemical properties are similar to those of simple Ni 2+ Similar, but when reacting with other substances, water molecules may participate in or affect the reaction process.

[0006] If there are organic carboxylic acids such as citric acid and tartaric acid in the wastewater, they can react with Ni 2+Forming complexes. For example, citric acid can react with Ni through multiple carboxyl and hydroxyl groups. 2+ In addition, some electronic industrial wastewater, printing and dyeing wastewater, etc. often contain strong complexing agents such as ethylenediaminetetraacetic acid (EDTA) and ethylene glycol diethyl ether diaminetetraacetic acid (EGTA). They react with Ni 2+ The formed complex is very stable. In the natural environment or under normal treatment conditions, it is not easy to dissociate Ni 2+ , which makes it difficult to directly remove it using traditional methods such as precipitation.

[0007] To meet this challenge, PCB manufacturers need to adopt efficient nickel-containing wastewater treatment technology. Although traditional chemical precipitation can remove some Ni 2+ However, there are problems such as large amount of sludge generated, high treatment cost, and inability to recycle nickel resources. Therefore, a nickel-containing wastewater recovery system is needed that can efficiently recover nickel resources and achieve standard discharge of wastewater. Summary of the invention

[0008] The invention overcomes the deficiencies of the prior art and provides a recovery system for nickel-containing wastewater to solve the problems existing in the prior art.

[0009] To achieve the above object, the technical solution adopted by the present invention is: a nickel-containing wastewater recovery system, including a physical and chemical subsystem, a reuse subsystem and a sludge subsystem; wherein

[0010] The physicochemical subsystem comprises a first regulating tank, a second regulating tank, a primary reaction tank, a secondary reaction tank, a coagulation reaction tank, a flocculation reaction tank and a sedimentation tank which are sequentially connected and arranged, wherein the first regulating tank performs mean and amount treatment on the nickel-containing wastewater, and the sedimentation tank is provided with a water outlet and a sewage outlet;

[0011] The reuse subsystem includes an intermediate water pool, a quartz sand filter, an activated carbon filter, a post-filtration water pool, a reverse osmosis security filter, a reverse osmosis device and a reuse water pool which are sequentially connected, and the intermediate water pool is connected to the water outlet of the sedimentation tank through a pipeline;

[0012] The sludge subsystem comprises a sludge concentration tank, a sludge dewatering machine and a sludge drying machine which are connected in sequence. The sludge concentration tank is connected to the sewage outlet of the sedimentation tank through a sludge discharge pump.

[0013] In a preferred embodiment of the present invention, the second regulating tank, the primary reaction tank, the secondary reaction tank, the coagulation reaction tank and the flocculation reaction tank are all reaction tanks made of carbon steel lining FRP material.

[0014] In a preferred embodiment of the present invention, the second regulating tank is connected to the first regulating tank through a wastewater delivery pump, 10% sulfuric acid solution and 10% sodium hydroxide solution are added to the second regulating tank to adjust the pH of the wastewater to 3-4, and the reaction time is 15 minutes.

[0015] In a preferred embodiment of the present invention, the complex breaking agent potassium persulfate, hydrogen peroxide and ferrous sulfate are put into the primary reaction tank for complex breaking reaction, and the reaction time is 15 minutes.

[0016] In a preferred embodiment of the present invention, a 10% sodium hydroxide solution is added to the secondary reaction tank to adjust the pH of the wastewater to 10, and then sodium sulfide is added to remove Ni 2+ At the same time, ferric chloride is added for coagulation treatment, and the reaction time is 15 minutes.

[0017] In a preferred embodiment of the present invention, a PAC solution with an effective Al2O3 content of 10% is added into the coagulation reaction tank to perform coagulation reaction on the wastewater.

[0018] In a preferred embodiment of the present invention, a 0.1% concentration of anionic PAM solution is added into the flocculation reaction tank to perform flocculation reaction on the wastewater.

[0019] In a preferred embodiment of the present invention, the quartz sand filter, the activated carbon filter and the filtered water pool are connected to a backwash pump via pipelines in sequence.

[0020] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0021] The nickel-containing wastewater recovery system of the present invention has the characteristics of simple equipment structure and low maintenance cost. The recovery system adopts three subsystems, namely, a physical and chemical subsystem, a reuse subsystem and a sludge subsystem, to operate in coordination. On the one hand, the efficient treatment and resource utilization of industrial wastewater are realized. The industrial wastewater is reused in production after deep treatment, which improves the recycling of water resources and protects the balance and stability of aquatic ecosystems. On the other hand, the cost of industrial water use is reduced, technological innovation and industrial upgrading are promoted, and the unity of economic benefits and environmental benefits is achieved through the standard discharge of wastewater and resource recycling, which is of great significance to the long-term development of enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further described below in conjunction with the accompanying drawings and embodiments;

[0023] Figure 1 is a structural diagram of a preferred embodiment of the present invention;

[0024] Figure 2 A flowchart of a preferred embodiment of the present invention;

[0025] In the figure:

[0026] 11. First regulating tank; 12. Second regulating tank; 13. Primary reaction tank; 14. Secondary reaction tank; 15. Coagulation reaction tank; 16. Flocculation reaction tank; 17. Sedimentation tank;

[0027] 21. Intermediate water pool; 22. Quartz sand filter; 23. Activated carbon filter; 24. Post-filtration water pool; 25. Reverse osmosis security filter; 26. Reverse osmosis device; 27. Recycled water pool;

[0028] 31. Sludge thickening tank; 32. Sludge dewatering machine; 33. Sludge drying machine;

[0029] 40. Wastewater transfer pump; 50. Pipeline-connected backwash pump; 60. Reverse osmosis water supply pump; 70. Reverse osmosis high-pressure pump; 80. Pool lift pump; 90. Sludge discharge pump; 100. Sludge feed pump. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0031] This embodiment provides a nickel-containing wastewater recovery system, which has the characteristics of simple equipment structure and low maintenance cost. On the one hand, it realizes the efficient treatment and resource utilization of industrial wastewater. The industrial wastewater is reused in production after deep treatment, which improves the recycling of water resources and protects the balance and stability of aquatic ecosystems. On the other hand, it reduces the cost of industrial water use, promotes technological innovation and industrial upgrading, and achieves the unity of economic and environmental benefits through the standard discharge of wastewater and resource recycling, which is of great significance to the long-term development of enterprises.

[0032] Combination Figure 1 and Figure 2As shown, the recovery system of this embodiment includes a physicochemical subsystem, a reuse subsystem and a sludge subsystem. The physicochemical subsystem includes a first regulating tank 11, a second regulating tank 12, a primary reaction tank 13, a secondary reaction tank 14, a coagulation reaction tank 15, a flocculation reaction tank 16 and a sedimentation tank 17 which are connected in sequence. The first regulating tank 11 treats the nickel-containing wastewater by an average value and an average amount. The sedimentation tank 17 is provided with a water outlet and a sewage outlet. The reuse subsystem includes an intermediate water tank 21, a quartz sand filter 22, an activated carbon filter 23, a filtered water tank 17 which are connected in sequence. The intermediate water tank 21 is connected to the outlet of the sedimentation tank 17 through a pipeline. The sludge subsystem includes a sludge thickening tank 31, a sludge dewatering machine 32 and a sludge dryer 33 which are connected in sequence. The sludge thickening tank 31 is connected to the sewage outlet of the sedimentation tank 17 through a sludge discharge pump 90. The second regulating tank 12, the primary reaction tank 13, the secondary reaction tank 14, the coagulation reaction tank 15 and the flocculation reaction tank 16 of this embodiment are all reaction tanks made of carbon steel lining FRP material.

[0033] In this embodiment, the second regulating tank 12 is connected to the first regulating tank 11 through a wastewater delivery pump 40, and a 10% concentration sulfuric acid solution and a 10% concentration sodium hydroxide solution are added into the second regulating tank 12 to adjust the pH of the wastewater to 3-4, and the reaction time is 15min. The primary reaction tank 13 is charged with a complex breaking agent potassium persulfate, hydrogen peroxide and ferrous sulfate for complex breaking reaction, and the reaction time is 15min. A 10% concentration sodium hydroxide solution is added into the secondary reaction tank 14 to adjust the pH of the wastewater to 10, and then sodium sulfide is added to remove Ni. 2+ At the same time, ferric chloride is added for coagulation treatment, the reaction time is 15 minutes, a PAC solution with an effective Al2O3 content of 10% is added to the coagulation reaction tank 15 to perform coagulation reaction on the wastewater, and a 0.1% concentration of anionic PAM solution is added to the flocculation reaction tank 16 to perform flocculation reaction on the wastewater.

[0034] Furthermore, the quartz sand filter 22, the activated carbon filter 23 and the post-filtration water pool 24 are connected in sequence to a backwash pump 50 via pipelines.

[0035] In actual use, the nickel-containing wastewater recovery system of this embodiment first homogenizes and adjusts the nickel-containing wastewater of FPC in the first regulating tank 11, then introduces the wastewater into the second regulating tank 12 through the wastewater delivery pump 40 to preliminarily adjust the pH, and adds sodium hydroxide and sulfuric acid to adjust the pH to 3-4. The purpose of this step is to adjust to the optimal pH of the subsequent Fenton reaction, and then enters the first reaction tank for complex breaking reaction, and adds potassium persulfate, hydrogen peroxide, and ferrous sulfate for oxidation treatment, the purpose of which is to oxidize the structurally stable complexed nickel into inorganic nickel. The complexed nickel is Ni 2+The complex is formed by coordination bonds with complexing agents. The coordination bonds have strong bond energy, which makes the complex structure stable. For example, Ni 2+ The complex formed with ethylenediaminetetraacetic acid (EDTA) has a high stability constant. Ordinary oxidants, such as sodium hypochlorite, cannot destroy its stable complex structure. This requires the use of Fenton's reagent. Under acidic conditions, ferrous ions catalyze the decomposition of hydrogen peroxide to produce hydroxyl radicals (·OH) with strong oxidizing properties. These hydroxyl radicals have extremely high oxidation potentials and can attack the complexing agent in the complexed nickel, causing it to undergo oxidative decomposition reactions and destroy the structure of the complex, thereby causing Ni 2+ Released from the complex. The released Ni 2+ It can be removed by subsequent precipitation and other methods.

[0036] Fenton reaction principle: Fe 2+ +H2O2→Fe 3+ +(OH)-+OH·

[0037] Potassium persulfate is also a strong oxidant. Its mechanism of reaction with organic matter is to break the hydrogen or hydroxyl hydrogen bonds connected to carbon atoms. Potassium persulfate combines with hydrogen atoms to generate potassium sulfate and sulfuric acid. Combining with Fenton can enhance the oxidation effect.

[0038] The dosage ratio of reagents in Fenton reaction is: H2O2 (mg / L): Ni 2+ (mg / L)=2:1, H2O2 (mg / L): Fe 2+ (mg / L)=3:1

[0039] Then it enters the secondary reaction tank 14, adds sodium hydroxide to adjust the pH to 10, and adds sodium sulfide and ferrous chloride at the same time. Sodium sulfide has a great influence on Ni 2+ Has a powerful net-catching effect, and Ni 2+ The reaction generates nickel sulfide (NiS) precipitation, thereby separating the heavy metals from the wastewater. At this time, the wastewater has already undergone the decomposition reaction in the primary reaction tank 13, and only ordinary sodium sulfide is needed to remove Ni in the wastewater. 2+ , which greatly reduces the wastewater treatment cost of this process.

[0040] Reaction principle: Ni 2+ +Na2S→NiS↓+2Na +

[0041] After the decomposition reaction is completed, PAC is added to the coagulation reaction tank 15 and PAM is added to the flocculation reaction tank 16 to assist sedimentation, and then enter the sedimentation tank 17. The effluent from the sedimentation tank 17 is connected to the intermediate water tank 21 and enters the quartz sand filter 22 through the water tank lifting pump 80.

[0042] The quartz sand filter 22 can effectively filter suspended particles such as silt, rust, algae, etc. in the water, and can ensure that the retained particles can be fully backwashed to reduce the concentration of suspended matter in the wastewater. And it can ensure that the retained particles can be fully backwashed to reduce the concentration of suspended matter in the wastewater.

[0043] The quartz sand filter 22 is filled with quartz sand with a particle size of 1-2 mm. The outlet of the quartz sand filter 22 is connected to the inlet of the activated carbon filter 23. The activated carbon filter 23 is mainly used to remove organic matter, odor, pigments and some heavy metals in the water. The activated carbon filled in the activated carbon filter 23 can reduce oxidizing substances in the water and play a security role for the reverse osmosis device 26.

[0044] The activated carbon filter 23 is filled with acid-washed coconut shell activated carbon with a particle size of 0.8-1.2mm. The water produced by the activated carbon filter 23 is connected to the post-filtration pool 24. The outlet of the post-filtration pool 24 is connected to the reverse osmosis water supply pump 60. The liquid is transported to the reverse osmosis security filter 25 through the reverse osmosis water supply pump 60. The shell of the reverse osmosis security filter 25 is made of FRP material with good anti-pollution performance and a pressure resistance level of 300psi. A PP filter element is placed inside with a filtration accuracy of 5μm. The function is to intercept particles larger than 5μm and prevent fine particles from entering the high-pressure pump and RO membrane elements and scratching the membrane surface. A discharge valve is set on the water pipe entering the reverse osmosis security filter 25, and an exhaust valve is set on the top of the reverse osmosis security filter 25.

[0045] The outlet of the reverse osmosis security filter 25 is connected to the inlet of the reverse osmosis high-pressure pump 70, and the outlet of the reverse osmosis high-pressure pump 70 is connected to the reverse osmosis device 26. The reverse osmosis high-pressure pump 70 provides sufficient osmotic pressure, and the outlet of the permeate after reverse osmosis desalination is connected to the inlet of the reuse water pool 27. The reuse water stored in the reuse water pool 27 can be transferred to the water use point by a pump.

[0046] The reverse osmosis device 26 is a reverse osmosis device 26 with an anti-pollution rolled reverse osmosis membrane element and a pressure resistance of 83 Bar.

[0047] In this embodiment, the sludge discharged from the sedimentation tank 17 enters the inlet of the sludge discharge pump 90 through a pipeline, and the sludge discharge pump 90 transfers the sludge to the sludge thickening tank 31. The outlet of the sludge thickening tank 31 is connected to the sludge feed pump 100, and the sludge is injected into the sludge dewatering machine 32. The sludge filtrate is connected to the inlet of the first regulating tank 11 through a pipeline, and the dewatered sludge enters the sludge dryer 33 for further concentration.

[0048] The sludge dewatering machine 32 is a chamber-type automatic high-pressure diaphragm filter press with a filtering pressure of 0.8 MPa, a squeezing pressure of 1.2 MPa, and equipped with an automatic flap, a sludge guide hopper, and a belt conveyor.

[0049] The sludge dryer 33 is a belt-type sludge dryer 33 which adopts a convection hot air drying method and a standard drying temperature of 68° C.-85° C., and the moisture content of the sludge output is less than 40%.

[0050] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A nickel-containing wastewater recovery system, characterized in that: It includes the physical and chemical subsystem, the recycling subsystem and the sludge subsystem; The physicochemical subsystem comprises a first regulating tank, a second regulating tank, a primary reaction tank, a secondary reaction tank, a coagulation reaction tank, a flocculation reaction tank and a sedimentation tank which are sequentially connected and arranged, wherein the first regulating tank performs mean and amount treatment on the nickel-containing wastewater, and the sedimentation tank is provided with a water outlet and a sewage outlet; The reuse subsystem includes an intermediate water pool, a quartz sand filter, an activated carbon filter, a post-filtration water pool, a reverse osmosis security filter, a reverse osmosis device and a reuse water pool which are sequentially connected, and the intermediate water pool is connected to the water outlet of the sedimentation tank through a pipeline; The sludge subsystem comprises a sludge concentration tank, a sludge dewatering machine and a sludge drying machine which are connected in sequence. The sludge concentration tank is connected to the sewage outlet of the sedimentation tank through a sludge discharge pump.

2. A nickel-containing wastewater recovery system according to claim 1, characterized in that: The second regulating tank, the primary reaction tank, the secondary reaction tank, the coagulation reaction tank and the flocculation reaction tank are all reaction tanks made of carbon steel lining and FRP material.

3. A nickel-containing wastewater recovery system according to claim 1, characterized in that: The second regulating tank is connected to the first regulating tank through a wastewater delivery pump. A 10% concentration sulfuric acid solution and a 10% concentration sodium hydroxide solution are added to the second regulating tank to adjust the pH of the wastewater to 3-4. The reaction time is 15 minutes.

4. A nickel-containing wastewater recovery system according to claim 1, characterized in that: The first-level reaction tank is charged with complex breaking agents, potassium persulfate, hydrogen peroxide and ferrous sulfate for complex breaking reaction, and the reaction time is 15 minutes.

5. A nickel-containing wastewater recovery system according to claim 1, characterized in that: The secondary reaction tank is filled with 10% sodium hydroxide solution to adjust the pH of the wastewater to 10, and then sodium sulfide is added to remove Ni 2+ At the same time, ferric chloride is added for coagulation treatment, and the reaction time is 15 minutes.

6. A nickel-containing wastewater recovery system according to claim 1, characterized in that: A PAC solution with an effective Al2O3 content of 10% is added into the coagulation reaction tank to carry out coagulation reaction on the wastewater.

7. A nickel-containing wastewater recovery system according to claim 1, characterized in that: A 0.1% concentration of anionic PAM solution is added into the flocculation reaction tank to carry out flocculation reaction on the wastewater.

8. A nickel-containing wastewater recovery system according to claim 1, characterized in that: The quartz sand filter, the activated carbon filter and the post-filtration water pool are connected to the backwash pump in sequence through pipelines.

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