Pretreatment system for high-concentration nickel sulfate wastewater

Abstract

The utility model discloses high concentration nickel sulfate wastewater pretreatment system, including the oil separation tank, the one side of oil separation tank is connected with the adjusting pool, the one side of adjusting pool is connected with a section Fenton tower and two section Fenton tower in proper order, the one side of two section Fenton tower is connected with primary coagulation sedimentation tank and secondary coagulation sedimentation tank in proper order, and the bottom of primary coagulation sedimentation tank and secondary coagulation sedimentation tank is connected with same first plate and frame filter press, the one side of secondary coagulation sedimentation tank is connected with intermediate water pool, and this high concentration nickel sulfate wastewater pretreatment system can produce strong oxidizability free radical through Fenton oxidation, ozone oxidation by coupling advanced oxidation and adsorption technology, and refractory macromolecular organic matter in nickel sulfate production wastewater is degraded into small molecular organic matter, and the residual organic matter in wastewater is further removed by virtue of the powerful adsorption capacity of activated carbon, and the effect of deep treatment is reached.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, and in particular to a pretreatment system for high-concentration nickel sulfate wastewater. Background Technology

[0002] Nickel sulfate (N i Nickel sulfate (SO4) is an important industrial raw material widely used in various fields, including electroplating, lithium battery manufacturing, catalyst production, and chemical reagent production. Due to its unique chemical properties, nickel sulfate can improve the wear resistance, corrosion resistance, and aesthetics of metal surfaces during electroplating. In lithium battery manufacturing, nickel sulfate is used to improve battery energy density and lifespan. In the field of catalysts, nickel sulfate can act as a catalyst to accelerate chemical reactions and improve product selectivity. Furthermore, nickel sulfate can be used to produce nickel salts, such as nickel ammonium sulfate and nickel potassium sulfate, which have wide applications in ceramics, glass, electronics, and pharmaceuticals. In recent years, with the rapid rise of the new energy vehicle industry, the demand for nickel sulfate in the production of power lithium batteries has been continuously increasing. According to the latest data, as of 2021, my country's nickel sulfate consumption was approximately 4 × 10⁵ tons, with power lithium batteries accounting for as much as 60%. This trend indicates that the future development prospects of the nickel sulfate market are even broader, with enormous development potential.

[0003] Currently, the main process for nickel sulfate production in my country is roughly as follows: "raw material leaching – purification – solid-liquid separation – extraction – crystallization." This process is simple, easy to operate, and has low production costs, but it generates a large amount of wastewater and waste gas, causing serious environmental pollution. Nickel sulfate production wastewater contains a large amount of sulfate and chloride ions, with a salt content exceeding 5%, and the wastewater has a strongly acidic pH. Furthermore, the wastewater has a high concentration of organic matter and an extremely low B / C ratio, making conventional biological treatment methods ineffective. Therefore, in actual production processes, companies typically use a "pretreatment + MVR evaporation crystallization" method. However, the initial investment and operating costs of MVR evaporation crystallization equipment are high, and the high salinity of the wastewater further increases the boiling point, requiring a large amount of steam to be consumed during operation. Moreover, the heat exchangers and pipes of the equipment are prone to scaling, affecting the efficiency of MVR evaporation crystallization. For companies with large daily processing volumes, the processing capacity of a single MVR unit is relatively limited, further increasing the company's wastewater treatment costs.

[0004] CN213738911U discloses a nickel sulfate production wastewater treatment system, which uses multi-stage reaction tanks to purify different heavy metal ions. However, it should be noted that nickel sulfate production wastewater typically also contains large amounts of organic matter, nitrogenous pollutants, and total phosphorus. Although this method is effective in treating heavy metal ions, its removal efficiency for other pollutants is relatively limited, making it difficult to meet increasingly stringent wastewater discharge standards. Therefore, a high-concentration nickel sulfate wastewater pretreatment system is proposed. Utility Model Content

[0005] To address the shortcomings of existing technologies, this utility model provides a high-concentration nickel sulfate wastewater pretreatment system, which solves the technical problems of high operating costs or inability to simultaneously remove multiple pollutants from wastewater in current high-salt nickel sulfate production wastewater treatment processes.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A high-concentration nickel sulfate wastewater pretreatment system includes an oil separator. One side of the oil separator is connected to an equalization tank. One side of the equalization tank is sequentially connected to a first-stage Fenton tower and a second-stage Fenton tower. One side of the second-stage Fenton tower is sequentially connected to a primary coagulation sedimentation tank and a secondary coagulation sedimentation tank. The bottom of the primary and secondary coagulation sedimentation tanks is connected to the same first plate and frame filter press. One side of the secondary coagulation sedimentation tank is connected to an intermediate water tank. One side of the intermediate water tank is connected to an ozone catalytic oxidation tower. One side of the ozone catalytic oxidation tower is connected to an activated carbon adsorption tower. One side of the activated carbon adsorption tower is connected to a terminal coagulation sedimentation tank. The bottom of the terminal coagulation sedimentation tank and the activated carbon adsorption tower is connected to the same second plate and frame filter press. A sludge hopper is installed below both the first and second plate and frame filter presses, and a sludge incinerator is installed on one side of the sludge hopper.

[0007] Preferably, the oil separator is provided with an oil-water inlet and a slag outlet on one side, and three oil-water separating plates are provided inside the oil separator. One side of each oil-water separating plate is provided with a slag separating plate, and both sides of the oil-water separating plates are provided with oil-water separating outlets. An oil-water separating outlet is provided on one side of the oil separator.

[0008] Preferably, both the regulating tank and the intermediate water tank are equipped with a water inlet and a water outlet, and both the regulating tank and the intermediate water tank are equipped with a mixer and a pH meter.

[0009] Preferably, both the first-stage and second-stage Fenton towers are equipped with tower body inlets and outlets. The outlet of the first-stage Fenton tower is connected to the inlet of the second-stage Fenton tower. Both the first-stage and second-stage Fenton towers are equipped with circulation inlets and outlets on one side, which are connected. Both the first-stage and second-stage Fenton towers are equipped with hydrogen peroxide distribution pipes. The first-stage Fenton tower is equipped with a ferrous oxide distribution pipe. Both the first-stage and second-stage Fenton towers are equipped with tower body water distributors.

[0010] Preferably, the primary coagulation sedimentation tank, the secondary coagulation sedimentation tank, and the terminal coagulation sedimentation tank are all provided with a mixing zone and a settling zone. A sedimentation inlet and a sedimentation outlet are provided on one side of each of the primary, secondary, and terminal coagulation sedimentation tanks. A sedimentation inlet pipe is provided in the mixing zone, with one end of the sedimentation inlet pipe extending to the settling zone. One end of the sedimentation inlet pipe is connected to a central pipe, and a sedimentation outlet is provided at the bottom of the central pipe. A sludge discharge port is provided at the bottom of each of the primary, secondary, and terminal coagulation sedimentation tanks. The sludge discharge ports at the bottom of the primary and secondary coagulation sedimentation tanks are connected to the first plate and frame filter press.

[0011] Preferably, the bottom of the ozone catalytic oxidation tower is provided with an oxidation water inlet and a tail gas collection port. An oxidation jet is connected to the bottom of the oxidation water inlet, and an ozone generator is connected to one side of the oxidation jet. An oxidation water distributor is provided inside the ozone catalytic oxidation tower.

[0012] Preferably, the activated carbon adsorption tower is provided with an adsorption inlet and an adsorption outlet tank. An adsorption jet injector and a guide tube are installed inside the activated carbon adsorption tower. The adsorption jet injector is located inside the guide tube, and an inclined plate is installed outside the guide tube. An agitator is installed on the activated carbon adsorption tower, and a backwash water pipe is connected to the agitator. One end of the agitator is equipped with a universal joint, and one side of the universal joint is connected to the backwash inlet. A filter head is installed on the activated carbon adsorption tower. The bottom of the activated carbon adsorption tower is connected to the sludge discharge port at the bottom of the end coagulation sedimentation tank, and a second plate and frame filter press is connected between the bottom of the first plate and frame filter press and the first layer of the second plate and frame filter press is provided with a filtrate return collection tank. An activated carbon feed port is provided on one side of the activated carbon adsorption tower.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows: This high-concentration nickel sulfate wastewater pretreatment system, through the coupling of advanced oxidation and adsorption processes, can generate highly oxidizing free radicals through Fenton oxidation and ozone oxidation, which degrade the recalcitrant large molecular organic matter in nickel sulfate production wastewater into small molecular organic matter. Activated carbon, with its strong adsorption capacity, further removes residual organic matter in the wastewater, achieving the effect of deep treatment. The entire process is not limited by the high salinity of the wastewater and eliminates the need for the domestication process of microorganisms in the biochemical system. After construction, it can directly treat wastewater. By optimizing the Fenton dosing and hydraulic exchange modes, the treatment efficiency of the Fenton process was effectively improved, and the organic load of subsequent processes was reduced. The activated carbon adsorption system effectively enhances the binding between activated carbon and pollutants in wastewater by optimizing its internal structure, thereby increasing adsorption efficiency. The sludge is incinerated and then recycled to avoid the risk of leakage during hazardous waste treatment. The recycled Ni can be reused in the production line to reduce raw material costs. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the structure of the oil separator and equalization tank of this utility model; Figure 3 This is a schematic diagram of the structure of the single-stage and double-stage Fenton towers of this utility model; Figure 4 This is a schematic diagram of the structure of the primary coagulation sedimentation tank, the secondary coagulation sedimentation tank, and the intermediate water tank of this utility model; Figure 5 This is a schematic diagram of the ozone catalytic oxidation tower, activated carbon adsorption tower, and terminal coagulation sedimentation tank of this utility model.

[0015] In the diagram: 1. Oil separator; 2. Equalization tank; 3. First-stage Fenton tower; 4. Second-stage Fenton tower; 5. First-stage coagulation sedimentation tank; 6. Second-stage coagulation sedimentation tank; 7. First plate and frame filter press; 8. Intermediate water tank; 9. Ozone catalytic oxidation tower; 10. Activated carbon adsorption tower; 11. Terminal coagulation sedimentation tank; 12. Second plate and frame filter press; 13. Sludge incinerator; 14. Oil separator inlet; 15. Slag separator plate; 16. Slag discharge port; 17. Oil separator baffle; 18. Oil separator water outlet; 19. Oil separator water outlet; 20. Water tank inlet; 21. Mixer; 22. pH meter; 23. Water tank outlet; 24. Tower inlet; 25. Tower water distributor; 26. Circulation inlet; 27. Circulation outlet. 28. Tower outlet; 29. ​​Hydrogen peroxide distribution pipe; 30. Ferrous oxide distribution pipe; 31. Mixing zone; 32. Settling zone; 33. Sedimentation inlet; 34. Sedimentation inlet pipe; 35. Central pipe; 36. Sedimentation outlet; 37. Sludge discharge port; 38. Sedimentation outlet tank; 39. Filtrate return to collection tank; 40. Sludge hopper; 41. Oxidation inlet; 42. Oxidation water distributor; 43. Oxidation jet injector; 44. Ozone generator; 45. Tail gas collection port; 46. Adsorption inlet; 47. Adsorption jet injector; 48. Guide tube; 49. Inclined plate; 50. Activated carbon feed port; 51. Agitator; 52. Backwash water pipe; 53. Backwash inlet; 54. Filter head; 55. Adsorption outlet tank. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Example: Refer to Figure 1-5 A high-concentration nickel sulfate wastewater pretreatment system includes an oil separator 1, an equalization tank 2 connected to one side of the oil separator 1, a first-stage Fenton tower 3 and a second-stage Fenton tower 4 connected sequentially to one side of the equalization tank 2, a first-stage coagulation sedimentation tank 5 and a second-stage coagulation sedimentation tank 6 connected sequentially to one side of the second-stage Fenton tower 4, a first-stage coagulation sedimentation tank 5 and a second-stage coagulation sedimentation tank 6 connected to the bottom of the first-stage coagulation sedimentation tank 5 and the second-stage coagulation sedimentation tank 6, an activated carbon adsorption tower 10 connected to one side of the second-stage coagulation sedimentation tank 6, an end coagulation sedimentation tank 11 connected to one side of the intermediate water tank 8, an ozone catalytic oxidation tower 9 connected to one side of the ozone catalytic oxidation tower 9, an activated carbon adsorption tower 10 connected to one side of the activated carbon adsorption tower 10, an end coagulation sedimentation tank 11 connected to one side of the end coagulation sedimentation tank 11 and the activated carbon adsorption tower 10, and a second-stage coagulation sedimentation tank 12 connected to the bottom of the end coagulation sedimentation tank 11 and the activated carbon adsorption tower 10, a sludge hopper 40 installed below both the first-stage coagulation sedimentation tank 7 and the second-stage coagulation sedimentation tank 12, and a sludge incinerator 13 installed on one side of the sludge hopper 40.

[0018] Furthermore, the oil separator 1 is equipped with an oil-water inlet 14 and a slag outlet 16 on one side. The oil separator 1 contains three oil-water baffles 17, with a slag-separating plate 15 on one side of each baffle 17. Oil-water inlets 18 are installed on both sides of the baffles 17. An oil-water outlet 19 is located on one side of the oil separator 1. Wastewater first enters the oil separator 1 for oil separation treatment. Due to the large amount of extractant used in the nickel sulfate production process, the wastewater contains a high oil content; failure to treat it will significantly impact the subsequent effluent. The oil separator 1 is divided by multiple oil-water baffles 17, with the inlet... A slag baffle 15 is installed below the inlet to separate larger impurities in the wastewater. A slag discharge port 16 is installed at the bottom of the tank to clean up the accumulated waste slag in the tank. There are multiple oil-water separating baffles 17 inside the oil-water separating tank 1. The bottom of the first and third oil-water separating baffles 17 is equipped with an oil-water separating outlet 18. Wastewater enters the subsequent tank through the oil-water separating outlet 18. Due to the low density of oil, after being separated by several stages of oil-water separating baffles 17, the oil is gradually separated and placed above the previous stages of the tank. An oil-water separating outlet 19 is installed at the bottom of the last stage of the tank. Wastewater enters the water inlet 20 of the regulating tank 2 through the oil-water separating outlet 19.

[0019] Furthermore, both the equalization tank 2 and the intermediate water tank 8 are equipped with water inlets 20 and water outlets 23. Both the equalization tank 2 and the intermediate water tank 8 are equipped with mixers 21 and pH meters 22. Both the first-stage Fenton tower 3 and the second-stage Fenton tower 4 are equipped with tower body inlets 24 and tower body outlets 28. The tower body outlet 28 of the first-stage Fenton tower 3 is connected to the tower body inlet 24 of the second-stage Fenton tower 4. Both the first-stage Fenton tower 3 and the second-stage Fenton tower 4 have circulation inlets 26 and circulation outlets 27 on one side, which are connected. Both the first-stage Fenton tower 3 and the second-stage Fenton tower 4 are equipped with hydrogen peroxide distribution pipes 29. The first-stage Fenton tower 3 has a ferrous oxide distribution pipe 30 inside. Both the first-stage Fenton tower 3 and the second-stage Fenton tower 4 are equipped with tower... The water distributor 25, the primary coagulation sedimentation tank 5, the secondary coagulation sedimentation tank 6 and the terminal coagulation sedimentation tank 11 are all equipped with a mixing zone 31 and a settling zone 32. The primary coagulation sedimentation tank 5, the secondary coagulation sedimentation tank 6 and the terminal coagulation sedimentation tank 11 are equipped with a settling inlet 33 and a settling outlet 38 on one side. The mixing zone 31 is equipped with a settling inlet pipe 34. One end of the settling inlet pipe 34 extends to the settling zone 32. One end of the settling inlet pipe 34 is connected to a central pipe 35. The bottom of the central pipe 35 is equipped with a settling outlet 36. The bottom of the primary coagulation sedimentation tank 5, the secondary coagulation sedimentation tank 6 and the terminal coagulation sedimentation tank 11 are all equipped with a sludge discharge port 37. The sludge discharge port 37 at the bottom of the primary coagulation sedimentation tank 5 and the secondary coagulation sedimentation tank 6 is connected to the first plate and frame filter press 7.

[0020] A pH meter 22 and a mixer 21 are installed in the equalization tank 2 to control the pH of the influent and to homogenize the wastewater, ensuring that the pH of the wastewater entering the Fenton system is between 3 and 3.5 to ensure the efficiency of the Fenton reaction. The homogenized wastewater undergoes Fenton treatment to degrade a large amount of organic matter. Fenton is a multi-stage process, which can effectively improve the utilization rate of wastewater reagents. Compared with the ordinary Fenton process, the COD removal rate of wastewater can be increased by 15-30%. The wastewater after Fenton treatment first enters the primary coagulation sedimentation tank 5, where alkali is added to cause some metal ions in the wastewater to form insoluble precipitates. Then, PAC and PAM are added for solid-liquid separation. Since nickel sulfate production wastewater usually contains a high concentration of nickel, some of which is in a complexed state, Fenton treatment can effectively remove most of the complexed nickel. Nickel is converted into nickel ions and removed in the primary coagulation and sedimentation process. However, some stubborn nickel remains that is difficult to treat. Therefore, for this type of wastewater, a secondary coagulation and sedimentation process is selected. During the secondary coagulation and sedimentation process, the pH of the wastewater is adjusted to 9.5-11, and sulfides are added as highly efficient heavy metal removal agents to combine with the remaining Ni in the wastewater. PAC and PAM are then added for coagulation and sedimentation. After treatment, the Ni concentration in the wastewater can be reduced to 0.1 mg / L. After solid-liquid separation in the sedimentation tank, the supernatant enters the intermediate water tank 8, and the sludge is pumped into the plate and frame filter press for treatment. The filtrate is returned to the homogenization tank. The remaining sludge is filtered to remove a large amount of water and then incinerated. The incinerated product is used for Ni recovery.

[0021] The Fenton reactor is a tower structure, consisting of a tower body, a tower inlet 24, a tower outlet 28, and a circulating water inlet. Inside the tower, from bottom to top, are arranged a tower distributor 25, a ferrous oxide chemical distribution pipe 30 (not included in the two-stage Fenton tower 4), and a hydrogen peroxide chemical distribution pipe 29. Wastewater enters the Fenton tower evenly through the tower distributor 25. The ferrous oxide chemical distribution pipe 30 and the hydrogen peroxide chemical distribution pipe 29 are arranged in a ring inside the tower, with downward openings. The wastewater and chemical reagent flow directions are opposite, which facilitates rapid mixing of the wastewater and chemical reagent. Circulating water inlets are located at the bottom and top of the Fenton tower. Inlet 26 and circulation outlet 27 are used to circulate the wastewater in the tower externally using a circulation pump. The residence time of the wastewater in the first-stage Fenton tower 3 is controlled at 30-120 minutes. The wastewater then enters the second-stage Fenton tower 4 from the top outlet. The second-stage Fenton tower 4 is generally the same as the first-stage Fenton tower 3, except that it lacks the ferricloth chemical tube 30. The residence time of the wastewater in the second-stage Fenton tower 4 is controlled at 30-120 minutes. The treated effluent enters the subsequent coagulation and sedimentation zone. Coagulation and sedimentation can be carried out using inclined plate tubes, vertical flow, etc., with vertical flow being used as an example. The primary coagulation sedimentation tank 5 consists of a mixing zone 31 and a settling zone 32. The mixing zone 31 is divided into three parts by a partition: a pH adjustment zone, a PAC dosing zone, and a PAM dosing zone. A sedimentation inlet pipe 34 is installed in the middle of the PAM dosing zone and connects to the settling zone 32. Wastewater enters the sedimentation inlet pipe 34 under pressure. The bottom of the sedimentation outlet 36 is sealed with a plug, while the outlet is open around the perimeter. Sludge accumulates in the conical hopper of the settling zone, and a sludge discharge port 37 at the bottom is used for periodic sludge removal. After treatment, the wastewater is discharged from the upper outlet and enters the secondary coagulation sedimentation tank 6. The secondary coagulation sedimentation tank 6 consists of a mixing zone 31 and a settling zone 32. The mixing zone 31 is divided into four parts by a partition: a pH adjustment zone, a sulfide dosing zone, a PAC dosing zone, and a PAM dosing zone. A sedimentation inlet pipe 34 is set in the middle of the PAM dosing zone and connected to the settling zone 32. Wastewater enters the sedimentation inlet pipe 34 under pressure. The bottom of the sedimentation outlet 36 is sealed with a plug, and water is discharged through the surrounding holes. Sludge accumulates in the cone hopper of the settling zone. A sludge discharge port 37 is opened at the bottom for periodic sludge removal. The effluent from the secondary coagulation sedimentation tank 6 enters the intermediate water tank 8.

[0022] Furthermore, the bottom of the ozone catalytic oxidation tower 9 is equipped with an oxidation inlet 41 and a tail gas collection port 45. An oxidation jet injector 43 is connected to the bottom of the oxidation inlet 41, and an ozone generator 44 is connected to one side of the oxidation jet injector 43. An oxidation water distributor 42 is installed inside the ozone catalytic oxidation tower 9, and a pH meter 22 and a stirrer 21 are installed in the intermediate water tank 8 to control the pH of the wastewater in the tank to 7-9. Since the ozone catalytic oxidation treatment effect is poor in acidic and strongly alkaline solutions, and in a strongly acidic environment, the surface of the catalyst may undergo protonation, which may change the active sites of the catalyst and thus affect the catalytic oxidation effect. The efficiency and selectivity of the oxidation reaction; in addition, an acidic environment may accelerate the corrosion or dissolution of the catalyst, further reducing its catalytic activity; under strongly alkaline conditions, the hydroxyl groups on the catalyst surface may change, leading to a reduction in active sites or decreased activity; furthermore, a strongly alkaline environment may also cause some components in the catalyst to hydrolyze or dissolve, which may also adversely affect its catalytic performance; in contrast, when the pH value is between 7 and 9, the solution is close to neutral or weakly alkaline; under these conditions, the catalyst can usually maintain good stability and activity, thus exhibiting a superior catalytic ozonation degradation effect.

[0023] Wastewater from intermediate water tank 8 is pumped into ozone catalytic oxidation tower 9. Ozone catalytic oxidation tower 9 is equipped with a baffle at the bottom and is filled with catalyst at the top to improve ozone utilization efficiency. After the effluent from intermediate water tank 8 and ozone are fully mixed by oxidation jet injector 43, they are evenly introduced into the tower through oxidation water distributor 42 at the bottom of the ozone tower. The water flow has full contact and exchange with the catalyst. Ozone tail gas is collected and treated by tail gas collection port 45 at the top of the tower. Circulation ports are set at the top and bottom of the ozone tower, and external circulation is carried out by circulation pump to improve ozone catalytic oxidation efficiency. Ozone effluent flows out from the outlet at the top of the tower and enters activated carbon adsorption tower 10.

[0024] Furthermore, the activated carbon adsorption tower 10 is equipped with an adsorption inlet 46 and an adsorption outlet tank 55. An adsorption jet injector 47 and a guide tube 48 are installed inside the activated carbon adsorption tower 10. The adsorption jet injector 47 is located inside the guide tube 48, and an inclined plate 49 is installed outside the guide tube 48. An agitator 51 is installed on the activated carbon adsorption tower 10, and a backwash water pipe 52 is connected to the agitator 51. A universal joint is installed at one end of the agitator 51, and a backwash inlet 53 is connected to one side of the universal joint. A filter head 5 is installed on the activated carbon adsorption tower 10. 4. The bottom of the activated carbon adsorption tower 10 is connected to the sludge discharge port 37 at the bottom of the end coagulation sedimentation tank 11, which is connected to the second plate and frame filter press 12. The first plate and frame filter press 7 and the first layer of the second plate and frame filter press 12 are provided with a filtrate return collection tank 39. An activated carbon feed port 50 is provided on one side of the activated carbon adsorption tower 10. From bottom to top, the activated carbon adsorption tower 10 is sequentially equipped with a sludge discharge pipe, an adsorption inlet 46, an activated carbon feed port 50, a backwash inlet 53, and an outlet weir. The bottom of the tower is designed as a cone shape, which helps the fluid to... The bottom facilitates smooth convergence and guidance; in the middle of the tower, a guide tube 48 is installed, with an adsorption jet 47 embedded inside. Its adsorption inlet 46 is directly connected to the inlet pipe, ensuring the uniformity and stability of the incoming water. Inclined plates 49 are cleverly arranged on the outside of the guide tube 48. These plates 49 not only enhance the fluid's guidance but also help increase the contact area between the activated carbon and the fluid. An agitator 51 and a backwash water pipe 52 are configured above the inclined plates 49, with the backwash water pipe 52 connected to the backwash inlet 53. Fixed on the rotating rod of the agitator 51, the backwash water pipe 52 can rotate freely inside the tower when the agitator is running. In addition, a filter head 54 is also provided at the top of the activated carbon adsorption tower 10. The effluent must first pass through this filter head 54 for fine filtration, and then flow out of the tower body through the effluent weir and enter the adsorption effluent tank 55. The activated carbon adsorption tower 10 backwashes the filter head 54 regularly. This design not only ensures the adsorption efficiency of activated carbon, but also facilitates the daily cleaning and maintenance of the tower body. After activated carbon adsorption, the effluent enters the terminal coagulation sedimentation tank 11.

[0025] The terminal coagulation sedimentation tank 11 consists of a mixing zone 31 and a settling zone 32. The mixing zone 31 is divided into three parts by a partition: a pH adjustment zone, a PAC dosing zone, and a PAM dosing zone. A sedimentation inlet pipe 34 is set in the middle of the PAM dosing zone and connected to the settling zone 32. Wastewater enters the sedimentation inlet pipe 34 under pressure. The bottom of the sedimentation outlet 36 is sealed with a plug, and water is discharged through the surrounding holes. Sludge accumulates in the cone hopper of the settling zone. The sludge is periodically pumped out through the bottom sludge discharge port 37. The effluent from the terminal coagulation sedimentation is discharged through the sedimentation outlet tank 38. The wastewater treatment process of this system is completed. After coagulation and sedimentation, the sludge first passes through the first plate and frame filter press 7 and the second plate and frame filter press 12. The filtrate is discharged back to the collection tank 39, and the sludge enters the sludge incinerator 13 for incineration. During the incineration process, a large amount of organic matter in the sludge is converted into carbon dioxide and water. The remaining ash contains metal ions that have settled during the initial coagulation and sedimentation. These ions can be further recycled through acid leaching and purification. On the one hand, this reduces the potential risks of treating sludge containing heavy metals. On the other hand, recycling can effectively save some production raw materials and improve the efficiency of green production.

[0026] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pretreatment system for high-concentration nickel sulfate wastewater, comprising an oil separator (1), characterized in that, One side of the oil separator (1) is connected to an equalization tank (2). One side of the equalization tank (2) is connected to a first-stage Fenton tower (3) and a second-stage Fenton tower (4). One side of the second-stage Fenton tower (4) is connected to a first-stage coagulation sedimentation tank (5) and a second-stage coagulation sedimentation tank (6). The bottom of the first-stage coagulation sedimentation tank (5) and the second-stage coagulation sedimentation tank (6) are connected to the same first plate and frame filter press (7). One side of the second-stage coagulation sedimentation tank (6) is connected to an intermediate water tank (8). One side of the intermediate water tank (8) is connected to... An ozone catalytic oxidation tower (9) is connected to one side of the ozone catalytic oxidation tower (9), an activated carbon adsorption tower (10) is connected to one side of the activated carbon adsorption tower (10), an end coagulation sedimentation tank (11) is connected to one side of the end coagulation sedimentation tank (11) and the bottom of the activated carbon adsorption tower (10) are connected to the same second plate and frame filter press (12). A sludge hopper (40) is provided below both the first plate and frame filter press (7) and the second plate and frame filter press (12). A sludge incinerator (13) is provided on one side of the sludge hopper (40).

2. The high-concentration nickel sulfate wastewater pretreatment system according to claim 1, characterized in that, The oil separator (1) is provided with an oil-water inlet (14) and a slag outlet (16) on one side. The oil separator (1) is provided with three oil-water baffles (17). A slag baffle (15) is provided on one side of one oil-water baffle (17). Oil-water inlets (18) are provided on both sides of the oil-water baffles (17). An oil-water outlet (19) is provided on one side of the oil separator (1).

3. The high-concentration nickel sulfate wastewater pretreatment system according to claim 1, characterized in that, The regulating tank (2) and the intermediate water tank (8) are each equipped with a water tank inlet (20) and a water tank outlet (23), and the regulating tank (2) and the intermediate water tank (8) are each equipped with a mixer (21) and a pH meter (22).

4. The high-concentration nickel sulfate wastewater pretreatment system according to claim 1, characterized in that, Both the first-stage Fenton tower (3) and the second-stage Fenton tower (4) are equipped with a tower body inlet (24) and a tower body outlet (28). The tower body outlet (28) on the first-stage Fenton tower (3) is connected to the tower body inlet (24) on the second-stage Fenton tower (4). Both the first-stage Fenton tower (3) and the second-stage Fenton tower (4) are equipped with a circulation inlet (26) and a circulation outlet (27) on one side. The circulation inlet (26) and the circulation outlet (27) are connected. Both the first-stage Fenton tower (3) and the second-stage Fenton tower (4) are equipped with a hydrogen peroxide distribution pipe (29). The first-stage Fenton tower (3) is equipped with a ferrihydride distribution pipe (30). Both the first-stage Fenton tower (3) and the second-stage Fenton tower (4) are equipped with a tower body water distributor (25).

5. The high-concentration nickel sulfate wastewater pretreatment system according to claim 1, characterized in that, The primary coagulation sedimentation tank (5), the secondary coagulation sedimentation tank (6), and the terminal coagulation sedimentation tank (11) are all equipped with a mixing zone (31) and a settling zone (32). A sedimentation inlet (33) and a sedimentation outlet (38) are provided on one side of the primary coagulation sedimentation tank (5), the secondary coagulation sedimentation tank (6), and the terminal coagulation sedimentation tank (11). A sedimentation inlet pipe (34) is provided in the mixing zone (31). One end of the sedimentation inlet pipe (34) extends to the settling zone (32). One end of the sedimentation inlet pipe (34) is connected to a central pipe (35). A sedimentation outlet hole (36) is provided at the bottom of the central pipe (35). A sludge discharge port (37) is provided at the bottom of the primary coagulation sedimentation tank (5), the secondary coagulation sedimentation tank (6), and the terminal coagulation sedimentation tank (11). The sludge discharge port (37) at the bottom of the primary coagulation sedimentation tank (5) and the secondary coagulation sedimentation tank (6) is connected to the first plate and frame filter press (7).

6. The high-concentration nickel sulfate wastewater pretreatment system according to claim 1, characterized in that, The bottom of the ozone catalytic oxidation tower (9) is provided with an oxidation water inlet (41) and a tail gas collection port (45). The bottom of the oxidation water inlet (41) is connected to an oxidation jet (43). An ozone generator (44) is connected to one side of the oxidation jet (43). An oxidation water distributor (42) is provided inside the ozone catalytic oxidation tower (9).

7. The high-concentration nickel sulfate wastewater pretreatment system according to claim 5, characterized in that, The activated carbon adsorption tower (10) is provided with an adsorption inlet (46) and an adsorption outlet tank (55). An adsorption jet (47) and a guide tube (48) are provided inside the activated carbon adsorption tower (10). The adsorption jet (47) is located inside the guide tube (48). An inclined plate (49) is provided outside the guide tube (48). An agitator (51) is provided on the activated carbon adsorption tower (10). A backwash water pipe (52) is connected to the agitator (51). A universal joint is provided at one end of the agitator (51). The universal joint is connected to a backwash inlet (53) on one side. The activated carbon adsorption tower (10) is equipped with a filter head (54). The bottom of the activated carbon adsorption tower (10) is connected to the sludge discharge port (37) at the bottom of the end coagulation sedimentation tank (11) and the second plate and frame filter press (12). The first plate and frame filter press (7) and the first layer of the second plate and frame filter press (12) are equipped with a filtrate return collection tank (39). The activated carbon adsorption tower (10) is equipped with an activated carbon feed port (50) on one side.

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