Stainless steel wastewater permanganate index advanced treatment method and system

Abstract

The application provides a stainless steel wastewater permanganate index deep treatment method and system, which comprises the following steps: conveying the stainless steel wastewater to be treated to an ozone catalytic tower provided with a modified biological charcoal catalyst for ozone catalytic oxidation treatment to obtain a first-stage treatment liquid; and conveying the first-stage treatment liquid to a modified activated carbon adsorption tower provided with modified activated carbon filler for adsorption treatment to obtain a second-stage treatment liquid. The stainless steel wastewater permanganate index deep treatment method and system can be used for special treatment of the permanganate index, realizes efficient and stable reduction of the permanganate index in the wastewater, and ensures that the permanganate index in the effluent can stably reach the III-class standard requirement of the Environmental Quality Standards for Surface Water (GB 3838-2002).

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a method and system for deep treatment of permanganate index of stainless steel wastewater. Background Technology

[0002] Stainless steel production wastewater is characterized by its complex composition and large fluctuations in water quality. Its sources mainly encompass multiple production stages, including pickling, passivation, cold rolling washing, and workshop floor washing. All types of wastewater contain varying degrees of recalcitrant organic matter, complexing agents, and heavy metals, forming a complex composite pollution system, resulting in generally high permanganate indices. With increasingly stringent requirements for watershed water environment management, stainless steel wastewater discharge needs to be upgraded from meeting the "Water Pollutant Discharge Standard for Iron and Steel Industry" (GB13456-2012) to consistently meeting the Class III standard of the "Surface Water Environmental Quality Standard" (GB 3838-2002) (permanganate index ≤ 6 mg / L). This places extremely high demands on the deep removal of organic pollutants and the stability of effluent.

[0003] However, existing conventional treatment processes for stainless steel wastewater primarily focus on removing heavy metals, adjusting pH levels, and reducing chemical oxygen demand (COD). For permanganate index, only basic co-treatment is typically performed: some suspended organic matter is removed during pretreatment by adjusting pH, or colloidal organic matter is separated through flocculation and sedimentation in subsequent heavy metal removal stages. No dedicated advanced treatment units are designed. While the permanganate index of conventionally treated wastewater meets the emission standards for the steel industry, it is difficult to consistently meet the Class III requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002). Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for deep treatment of permanganate index in stainless steel wastewater, in order to solve one or more of the problems in the existing conventional treatment processes for stainless steel wastewater, such as the lack of a deep treatment method for permanganate index, which makes it difficult for the permanganate index test results of the wastewater to consistently meet the Class III standard requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for deep treatment of permanganate index in stainless steel wastewater, comprising:

[0006] The stainless steel wastewater to be treated is transported to an ozone catalytic tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treated liquid.

[0007] The primary treated liquid is transported to a modified activated carbon adsorption tower equipped with modified activated carbon packing for adsorption treatment to obtain a secondary treated liquid.

[0008] Optionally, the stainless steel wastewater to be treated has the following characteristics: pH value of 6-9 and permanganate index of 32 mg / L-49 mg / L.

[0009] Optionally, the step of conveying the stainless steel wastewater to be treated to an ozone catalytic tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treated liquid includes: conveying the stainless steel wastewater to be treated to an ozone catalytic tower equipped with a modified biochar catalyst via a primary inlet pump; and supplying ozone to the ozone catalytic tower through an ozone generator so that the stainless steel wastewater to be treated, the modified biochar catalyst, and the ozone undergo an ozone catalytic oxidation reaction in the ozone catalytic tower to obtain the primary treated liquid.

[0010] Optionally, in the ozone catalytic tower, the ozone inlet concentration is 75 mg / L to 93 mg / L, and the ozone utilization rate is 89% to 93%.

[0011] Optionally, the modified biochar catalyst is packed in a volume that accounts for 80% to 85% of the effective volume of the ozone catalytic tower, and the flow rate of the stainless steel wastewater to be treated in the ozone catalytic tower is 4.3 m / h to 5.8 m / h.

[0012] Optionally, the modified biochar catalyst is prepared by the following steps: cotton stalks are selected as the biochar raw material, rinsed with water 2 to 3 times, and a 32% to 47% phosphoric acid solution is prepared. The cotton stalks are soaked in the phosphoric acid solution for 67 to 112 minutes, removed and dried, and then placed in a 105°C oven for 65 to 145 minutes, followed by natural cooling to obtain pretreated cotton stalks. The pretreated cotton stalks are then placed in a muffle furnace and heated to 520°C to 535°C at a heating rate of 4°C to 7°C per minute under nitrogen protection, held for 45 to 65 minutes, and then naturally cooled to obtain cotton stalk biochar. The cotton stalk biochar was prepared by grinding it into 100-200 mesh fine powder. 100-200 mesh bentonite was selected as an inorganic binder and mixed with the cotton stalk biochar fine powder at a mass ratio of 1:(3-4). The mixture was added to a twin-shaft mixer and premixed at a speed of 75-95 rpm for 2-3 minutes. Deionized water was then sprayed in, controlling the total moisture content to be 12%-15%. The mixture was then placed in a first reaction vessel, which was kept at a constant temperature of 53-56℃ and mixed at a speed of 75-95 rpm. The mixture is stirred at a stirring speed of 95 rpm for 35 to 40 minutes, and then cooled to obtain a cooled mixture. The cooled mixture is then placed into a twin-screw extruder for granulation. In the twin-screw extruder, the screw speed is 95 rpm to 115 rpm, the die temperature is 215°C to 225°C, and the extrusion pressure is 9.3 MPa to 11.2 MPa to obtain biochar granules. A cobalt nitrate solution with a concentration of 0.2 mol / L to 0.5 mol / L and a nickel nitrate solution with a concentration of 0.2 mol / L to 0.7 mol / L are prepared, and the cobalt nitrate solution and the nickel nitrate solution are mixed at a volume ratio of (2 to 3):1. A mixed solution was obtained; the mixed solution was placed in a second reaction vessel, and the biochar particles were added to the mixed solution at a liquid-to-solid ratio of (6~8) mL: 1 g. Under nitrogen protection, the second reaction vessel was heated to 78℃~83℃, then heated to 125℃~135℃ and hydrothermally reacted for 10~15 hours. After natural cooling, the solid product was obtained by filtration, and the solid product was washed with deionized water until neutral, and then dried at 105℃ for 75 minutes~105 minutes to obtain the modified biochar catalyst; wherein, the compressive strength of the modified biochar catalyst is 3.5 MPa~4.5 MPa, and the specific surface area is 167.1 m². 2 / g~187.6m 2 / g, with a metal loading rate of 5.1%~6.3%.

[0013] Optionally, the modified activated carbon filler is prepared by the following steps: selecting a specific surface area of ​​850 m².2 / g~960m 2 / g of coal-based crushed activated carbon, fluidized bed coal gasification slag with a particle size of 100-200 mesh, and non-self-igniting coal gangue with a particle size of 100-200 mesh; the fluidized bed coal gasification slag and the non-self-igniting coal gangue are washed 2-3 times with clean water, dried at 105℃ for 12 hours, and a hydrochloric acid solution with a concentration of 2.1mol / L-2.6mol / L is prepared. The fluidized bed coal gasification slag and the non-self-igniting coal gangue are mixed at a volume ratio of (2-4):1 to obtain a solid mixture. The solid mixture is immersed in the hydrochloric acid solution at a solid-liquid ratio of 1g:(4-7)mL and stirred at a stirring speed of 115 rpm-135 rpm for 45-55 minutes to obtain an acid-treated mixture. The acid-treated mixture is filtered, washed with water until neutral, and then heated at 110℃. The mixture is dried at ℃ to obtain a pretreated mixture; the pretreated mixture is mixed with the coal-based crushed activated carbon at a mass ratio of (2~3):1, and deionized water is added as a binder. The mixture is stirred in a mixer at a stirring speed of 65 rpm to 75 rpm for 10 to 15 minutes to obtain a mixture. The mixture is then placed in an extrusion granulator for granulation to obtain granular products. The granular products are placed in a muffle furnace and preheated at 75℃ to 80℃ for 50 to 55 minutes. The temperature is then increased to 385℃ to 393℃ at a heating rate of 3℃ to 5℃ per minute and held for 45 to 55 minutes. The temperature is then increased to 555℃ to 565℃ at a heating rate of 6℃ to 8℃ per minute and held for 35 to 45 minutes. The mixture is then cooled to obtain the modified activated carbon filler.

[0014] Optionally, the specific surface area of ​​the modified activated carbon filler is 895.1 m². 2 / g~1078.3m 2 / g, with a maximum adsorption capacity of 56.2mg / g to 64.1mg / g for organic matter.

[0015] Optionally, the filling volume of the modified activated carbon packing accounts for 80% to 85% of the effective volume of the modified activated carbon adsorption tower, and the flow rate of the primary treatment liquid in the modified activated carbon adsorption tower is 6 m / h to 7 m / h.

[0016] To achieve the above objectives, the present invention also provides a deep treatment system for permanganate index of stainless steel wastewater. The system includes an ozone catalytic oxidation unit and an adsorption unit arranged sequentially. The ozone catalytic oxidation unit includes a primary influent pump and an ozone catalytic tower connected in sequence, and an ozone generator connected to the ozone catalytic tower. The ozone catalytic tower contains a modified biochar catalyst. The adsorption unit includes a secondary influent pump, a modified activated carbon adsorption tower, and an effluent pump connected in sequence. The inlet of the secondary influent pump is connected to the effluent of the ozone catalytic tower. The modified activated carbon adsorption tower contains modified activated carbon packing. The primary influent pump is configured to pump the stainless steel wastewater to be treated... Wastewater is transported to the ozone catalytic tower; the ozone generator is configured to supply ozone to the ozone catalytic tower; the ozone catalytic tower is configured to receive the stainless steel wastewater to be treated and the ozone, and to cause the stainless steel wastewater to be treated, the modified biochar catalyst, and the ozone to undergo an ozone catalytic oxidation reaction in the ozone catalytic tower to obtain a primary treated liquid; the secondary inlet pump is configured to transport the primary treated liquid to the modified activated carbon adsorption tower; the modified activated carbon adsorption tower is configured to use the modified activated carbon packing to adsorb and treat the primary treated liquid to obtain a secondary treated liquid; the outlet pump is configured to discharge the secondary treated liquid.

[0017] Compared with existing technologies, the deep treatment method and system for permanganate index of stainless steel wastewater provided by the present invention has the following beneficial effects:

[0018] The present invention provides a method for deep treatment of permanganate index in stainless steel wastewater, comprising: conveying the stainless steel wastewater to be treated to an ozone catalytic tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treated liquid; and conveying the primary treated liquid to a modified activated carbon adsorption tower equipped with modified activated carbon packing for adsorption treatment to obtain a secondary treated liquid. Thus, the present invention provides a method for deep treatment of permanganate index in stainless steel wastewater by conveying the stainless steel wastewater to be treated to an ozone catalytic tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment. The modified biochar catalyst has a rough and porous surface, exhibiting good water absorption and ion exchange capacity, and possesses good physical properties. During the ozone catalytic oxidation treatment, it can effectively convert ozone into hydroxyl radicals, effectively degrading and adsorbing organic matter in the wastewater, and efficiently and stably reducing the permanganate index in the wastewater. Furthermore, by conveying the primary treated liquid to a modified activated carbon adsorption tower equipped with modified activated carbon packing for adsorption treatment, the modified activated carbon packing has a large specific surface area and a high adsorption capacity for organic matter, which can further reduce the permanganate index in the primary treated liquid. Finally, by adopting the deep treatment method for permanganate index of stainless steel wastewater provided by the present invention, it is possible to carry out special treatment on permanganate index, achieve efficient and stable reduction of permanganate index in wastewater, and ensure that the permanganate index in the effluent can stably meet the Class III standard requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0019] Since the stainless steel wastewater permanganate index deep treatment system provided by this invention belongs to the same inventive concept as the stainless steel wastewater permanganate index deep treatment method described in any of the above claims, the stainless steel wastewater permanganate index deep treatment system provided by this invention has at least all the advantages of the stainless steel wastewater permanganate index deep treatment method provided by this invention. For the advantages of the stainless steel wastewater permanganate index deep treatment system provided by this invention, please refer to the relevant description of the beneficial effects of the stainless steel wastewater permanganate index deep treatment method provided by this invention, which will not be repeated here. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall steps of a deep treatment method for permanganate index of stainless steel wastewater provided in Embodiment 1 of the present invention;

[0021] Figure 2 This is a schematic diagram of the specific process of a deep treatment method for permanganate index of stainless steel wastewater provided in Embodiment 1 of the present invention;

[0022] Figure 3 This is a structural block diagram of a deep treatment system for permanganate index of stainless steel wastewater provided in Embodiment 2 of the present invention;

[0023] The annotations in the attached figures are explained as follows:

[0024] 1-Ozone catalytic oxidation unit, 11-First stage water inlet pump, 12-Ozone catalytic tower, 13-Ozone generator;

[0025] 2-Adsorption unit, 21-Secondary inlet pump, 22-Modified activated carbon adsorption tower, 23-Outlet pump. Detailed Implementation

[0026] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the deep treatment method and system for permanganate index of stainless steel wastewater proposed in this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, used only to facilitate and clarify the illustration of the embodiments of this invention. Please refer to the drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this invention. Any modifications to the structure, changes in proportions, or adjustments to the size, provided that the effects and objectives achieved by this invention are the same or similar, should still fall within the scope of the technical content disclosed in this invention. Specific design features of the invention disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the specific application and usage environment. Furthermore, in the embodiments described below, the same reference numerals are sometimes used across different drawings to denote the same parts or parts having the same function, omitting repeated descriptions.

[0027] It should be understood that, unless specifically stated or obvious from the context, as used herein, the term “about” is understood to mean within the normal tolerance range in the field, such as within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise specified from the context, all numerical values ​​provided herein are modified by the term “about”.

[0028] Example 1

[0029] This embodiment provides a method for the advanced treatment of permanganate index in stainless steel wastewater. For details, please refer to [link to relevant documentation]. Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the overall steps of the deep treatment method for permanganate index of stainless steel wastewater provided in this embodiment; Figure 2 This is a schematic flowchart illustrating the deep treatment method for permanganate index of stainless steel wastewater provided in this embodiment. Figure 1 and Figure 2 As can be seen, the method includes:

[0030] S100: The stainless steel wastewater to be treated is transported to the ozone catalytic tower 12 equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain the first-grade treated liquid.

[0031] S200: The primary treatment liquid is transported to a modified activated carbon adsorption tower 22 equipped with modified activated carbon packing for adsorption treatment to obtain a secondary treatment liquid.

[0032] Therefore, the deep treatment method for permanganate index of stainless steel wastewater provided in this embodiment involves conveying the stainless steel wastewater to an ozone catalytic tower 12 equipped with a modified biochar catalyst for ozone catalytic oxidation treatment. This modified biochar catalyst has a rough and porous surface, exhibiting good water absorption and ion exchange capacity, and possesses excellent physical properties. During ozone catalytic oxidation, it can effectively convert ozone into hydroxyl radicals, effectively degrading and adsorbing organic matter in the wastewater, thus efficiently and stably reducing the permanganate index. Furthermore, the primary treated liquid is conveyed to a modified activated carbon adsorption tower 22 equipped with modified activated carbon packing for adsorption treatment. This modified activated carbon packing has a large specific surface area and a high adsorption capacity for organic matter, further reducing the permanganate index in the primary treated liquid. Finally, by employing the deep treatment method for permanganate index of stainless steel wastewater provided by this invention, specific treatment of the permanganate index can be achieved, realizing efficient and stable reduction of the permanganate index in the wastewater, ensuring that the permanganate index in the effluent consistently meets the Class III standard requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0033] It should be noted that the stainless steel wastewater to be treated has met the limit requirements in Table 2 of the "Water Pollutant Discharge Standard for Iron and Steel Industry" (GB 13456-2012). For example, in some embodiments, the water quality of the stainless steel wastewater to be treated is: pH value of 6-9, and permanganate index of 32 mg / L-49 mg / L.

[0034] Preferably, in step S100, the step of conveying the stainless steel wastewater to be treated to an ozone catalytic tower 12 equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treated liquid includes: conveying the stainless steel wastewater to be treated to the ozone catalytic tower 12 equipped with a modified biochar catalyst via a primary inlet pump 11; and providing ozone to the ozone catalytic tower 12 through an ozone generator 13, so that the stainless steel wastewater to be treated, the modified biochar catalyst, and the ozone undergo an ozone catalytic oxidation reaction in the ozone catalytic tower 12 to obtain the primary treated liquid.

[0035] For example, in some embodiments, the stainless steel wastewater to be treated enters the ozone catalytic tower 12 from the bottom via a primary inlet pump 11 and flows out from bottom to top; the ozone generator 13 is an oxygen source generator, and the ozone generated also enters from the bottom of the ozone catalytic tower 12 and then fills the entire ozone catalytic tower 12.

[0036] For example, in some exemplary embodiments, the ozone inlet concentration in the ozone catalytic tower 12 is 75 mg / L to 93 mg / L, and the ozone utilization rate is 89% to 93%; the modified biochar catalyst accounts for 80% to 85% of the effective volume of the ozone catalytic tower 12, and the flow rate of the stainless steel wastewater to be treated in the ozone catalytic tower 12 is 4.3 m / h to 5.8 m / h.

[0037] Exemplarily, in some embodiments, the modified biochar catalyst is prepared by the following steps:

[0038] SA1: Select cotton stalks as biochar raw material, rinse them with clean water 2 to 3 times, and prepare a phosphoric acid solution with a concentration of 32% to 47%. Soak the cotton stalks in the phosphoric acid solution for 67 minutes to 112 minutes, take them out and dry them, and then put them in an oven at 105℃ for 65 minutes to 145 minutes. After natural cooling, the pretreated cotton stalks are obtained.

[0039] SA2: The pretreated cotton stalks are placed in a muffle furnace and heated to 520°C to 535°C at a heating rate of 4°C / min to 7°C / min under nitrogen protection. The temperature is maintained at this temperature for 45 minutes to 65 minutes and then naturally cooled to obtain cotton stalk biochar. The cotton stalk biochar is then ground into fine powder in a grinder, and 100-200 mesh cotton stalk biochar fine powder is selected.

[0040] SA3: Select 100-200 mesh bentonite as an inorganic binder, mix the bentonite with the cotton straw biochar powder at a mass ratio of 1:(3-4) to obtain a mixture, add the mixture to a twin-shaft mixer, and premix at a rate of 75 rpm to 95 rpm for 2 to 3 minutes. Then, slowly spray in deionized water and control the total water content to be 12% to 15% (on a wet basis). After that, put the mixture into a sealed first reaction vessel, keep the temperature of the first reaction vessel constant at 53℃ to 56℃, and stir at a stirring speed of 75 rpm to 95 rpm for 35 to 40 minutes. Cool to obtain a cooled mixture.

[0041] SA4: The cooled mixture is fed into a twin-screw extruder for granulation. In the twin-screw extruder, the screw speed is 95 rpm to 115 rpm, and the die temperature is 215°C to 225°C. The high temperature can induce slight thermoplasticity in the biochar-bentonite composite system, which can significantly improve the particle density and compressive strength. The die is a circular die with a 2.0 mm aperture, and the extrusion pressure is 9.3 MPa to 11.2 MPa to ensure that the particle structure is uniform and free of voids, thus preparing biochar particles with a diameter of 2.0 mm.

[0042] SA5: Prepare a cobalt nitrate solution with a concentration of 0.2 mol / L to 0.5 mol / L and a nickel nitrate solution with a concentration of 0.2 mol / L to 0.7 mol / L. Mix the cobalt nitrate solution and the nickel nitrate solution at a volume ratio of (2~3):1 to obtain a mixed solution.

[0043] SA6: Place the mixed solution into the second reaction vessel, add the biochar particles to the mixed solution at a liquid-to-solid ratio of (6~8) mL: 1 g, and heat the second reaction vessel to 78℃~83℃ under nitrogen protection. At this temperature, the biochar particles are fully wetted and uniformly dispersed. Then, the temperature is raised to 125℃~135℃ to carry out a hydrothermal reaction, and the hydrothermal reaction is carried out for 10~15 hours. The hydrothermal reaction process is conducive to the directional growth and firm anchoring of metal oxide / hydroxide nanocrystals on the surface of biochar. After the hydrothermal reaction is completed, the mixture is naturally cooled, filtered and separated to obtain a solid product, and the solid product is washed with deionized water until neutral. Then, it is dried at 105℃ for 75 minutes~105 minutes to obtain the modified biochar catalyst.

[0044] Therefore, the modified biochar catalyst prepared through the above steps has a rough and porous surface, exhibiting good water absorption and ion exchange capabilities; moreover, the modified biochar catalyst has a compressive strength of 3.5 MPa to 4.5 MPa and a specific surface area of ​​167.1 m². 2 / g~187.6m 2 / g, with a metal loading rate of 5.1%~6.3% (measured by weight); in addition, the modified biochar catalyst has good physical properties and can effectively convert ozone into hydroxyl radicals during ozone catalytic oxidation treatment, which can effectively degrade and adsorb organic matter in wastewater, thereby efficiently and stably reducing the permanganate index in wastewater.

[0045] It should be noted that the parameters given in the preparation process of the modified biochar catalyst are only illustrative examples, and these parameters should be reasonably set according to the water quality characteristics of the stainless steel wastewater to be treated.

[0046] For example, in some embodiments, the water quality characteristics of the primary treated liquid obtained after the stainless steel wastewater to be treated is as follows: permanganate index is 8 mg / L to 11 mg / L.

[0047] Further, in step S200, the primary treatment liquid can be transported by the secondary inlet pump 21 to the modified activated carbon adsorption tower 22 equipped with modified activated carbon packing for adsorption treatment to obtain the secondary treatment liquid, and the secondary treatment liquid can be discharged by the outlet pump 23.

[0048] Preferably, in some embodiments, the modified activated carbon filler is prepared by the following steps:

[0049] SB1: Select a specific surface area of ​​850m² 2 / g~960m 2 / g of coal-based crushed activated carbon, fluidized bed coal gasification slag with a particle size of 100-200 mesh, and non-self-igniting coal gangue with a particle size of 100-200 mesh; wherein, the fluidized bed coal gasification slag is coal gasification slag taken from the fluidized bed gasification process, which has a porous structure and high residual carbon content, which is beneficial for preparing adsorption materials; the main components of the non-self-igniting coal gangue are aluminosilicate minerals such as kaolinite and illite.

[0050] SB2: Rinse the gasification slag and the non-self-igniting coal gangue with clean water 2 to 3 times to remove soluble salts. Then, dry them at 105°C for 12 hours. Prepare a hydrochloric acid solution with a concentration of 2.1 mol / L to 2.6 mol / L. Mix the gasification slag and the non-self-igniting coal gangue at a volume ratio of (2 to 4):1 to obtain a solid mixture. Immerse the solid mixture in the hydrochloric acid solution at a solid-liquid ratio of 1 g to (4 to 7) mL and stir at a stirring speed of 115 rpm to 135 rpm for 45 to 55 minutes. The purpose of acid washing here is to remove some metal oxides and at the same time to expand the pores and increase the volume. The acid-treated mixture is then filtered, washed with water until neutral, and dried at 110°C to obtain the pretreated mixture.

[0051] SB3: The pretreated mixture is mixed with the coal-based crushed activated carbon at a mass ratio of (2~3):1, and deionized water is added as a binder. The mixture is stirred in a mixer at a stirring speed of 65 rpm to 75 rpm for 10 to 15 minutes to obtain a plastic mixture. The mixture is then placed into an extrusion granulator for granulation to obtain cylindrical granules with a diameter of 2.0 mm. The extrusion granulator is a twin-screw extrusion granulator with a screw speed of 95 rpm to 115 rpm, a die temperature of 215℃ to 225℃, a circular die with a hole diameter of 2.0 mm, and an extrusion pressure of 9.3 MPa to 11.2 MPa.

[0052] SB4: The particulate product is placed in a muffle furnace and preheated at 75℃~80℃ for 50 to 55 minutes. Then, the temperature is increased to 385℃~393℃ at a rate of 3℃ / min~5℃ / min and held for 45 to 55 minutes. At this temperature, organic matter can be removed. Then, the temperature is increased to 555℃~565℃ at a rate of 6℃ / min~8℃ / min and held at a constant temperature for 35 to 45 minutes. This allows the aluminosilicate minerals in the non-self-igniting coal gangue and the residual carbon in the gasification slag of the fluidized bed coal gasification to further form a stable composite structure. The product is then cooled with the furnace to obtain the modified activated carbon filler.

[0053] Therefore, the modified activated carbon filler prepared through the above steps has a particle size of 2.0 mm and a specific surface area of ​​895.1 m². 2 / g~1078.3m 2 / g, with a maximum adsorption capacity of 56.2mg / g~64.1mg / g for organic matter, and can further reduce the permanganate index in the primary treatment solution during the adsorption process.

[0054] It should be noted that the parameters given in the preparation process of the modified activated carbon packing are only illustrative examples, and these parameters should be reasonably set according to the water quality characteristics of the stainless steel wastewater to be treated.

[0055] For example, in some embodiments, the modified activated carbon packing volume accounts for 80% to 85% of the effective volume of the modified activated carbon adsorption tower 22, and the flow rate of the primary treatment liquid in the modified activated carbon adsorption tower 22 is 6 m / h to 7 m / h.

[0056] For example, in some embodiments, the water quality characteristics of the secondary treated liquid obtained after the primary treated liquid is adsorbed by the modified activated carbon adsorption tower 22 are: pH value of 6~9, permanganate index of 2mg / L~4mg / L, and the permanganate index meets the Class III standard requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0057] To facilitate a further understanding of the present invention, the following two specific examples illustrate the present invention by treating stainless steel wastewater that has reached the limit requirements of Table 2 of the "Water Pollutant Discharge Standard for Iron and Steel Industry" (GB 13456-2012) using the deep treatment method for permanganate index of stainless steel wastewater provided by the present invention.

[0058] Example 1: The water quality characteristics of the stainless steel wastewater to be treated are: pH value approximately 7.2, permanganate index approximately 36 mg / L. The treatment steps for this stainless steel wastewater are as follows:

[0059] First, the stainless steel wastewater to be treated is pumped to an ozone catalytic tower 12 equipped with a modified biochar catalyst via a primary inlet pump 11. The wastewater enters the tower from the bottom and flows out from the top. An ozone generator 13, which is also an oxygen source generator, is connected to the ozone catalytic tower 12. The generated ozone also enters the tower from the bottom and fills the entire tower. The ozone concentration in the ozone catalytic tower 12 is 79 mg / L, and the ozone utilization rate is 91%. The modified biochar catalyst occupies 80% of the effective volume of the ozone catalytic tower 12, and the flow velocity of the stainless steel wastewater in the tower is 4.9 m / h. After ozone catalytic oxidation treatment in the ozone catalytic tower 12, a primary treated liquid is obtained, which has a permanganate index of 9 mg / L.

[0060] Specifically, in this example, the modified biochar catalyst is prepared through the following steps: First, cotton stalks are selected as the biochar raw material, rinsed twice with water, and a 36% phosphoric acid solution is prepared. The cotton stalks are soaked in the phosphoric acid solution for 85 minutes, removed and dried, and then placed in a 105°C oven for 90 minutes. After natural cooling, pretreated cotton stalks are obtained. Next, the pretreated cotton stalks are placed in a muffle furnace and heated to 520°C at a heating rate of 5°C / min under nitrogen protection. This temperature is maintained for 52 minutes, and after natural cooling, cotton stalk biochar is obtained. The cotton stalk biochar is then ground into a fine powder using a grinder. 100-mesh cotton stalk biochar powder was selected; then, 100-mesh bentonite was selected as an inorganic binder. The bentonite and cotton stalk biochar powder were mixed at a mass ratio of 1:3 to obtain a mixture. This mixture was added to a twin-shaft mixer and premixed at 78 rpm for 2 minutes. Deionized water was then slowly sprayed in, controlling the total moisture content to 13% (wet basis). The mixture was then placed in a sealed first reaction vessel, which was maintained at a constant temperature of 53°C and stirred at 81 rpm for 36 minutes. The mixture was then cooled to obtain a cooled mixture. Finally, the cooled mixture was placed into a twin-screw extruder granulator. Granulation is performed using a twin-screw extruder with a screw speed of 100 rpm and a die temperature of 218°C. The high temperature induces slight thermoplasticity in the biochar-bentonite composite system, significantly improving particle density and compressive strength. The die is a circular die with a 2.0 mm aperture, and the extrusion pressure is 9.5 MPa, ensuring a uniform particle structure without voids, resulting in biochar particles with a diameter of 2.0 mm. Next, a 0.3 mol / L cobalt nitrate solution and a 0.5 mol / L nickel nitrate solution are prepared and mixed at a volume ratio of 2:1 to obtain a mixed solution. Then, the... The mixed solution was placed in a second reaction vessel, and the biochar particles were added to the mixed solution at a liquid-to-solid ratio of 6 mL:1 g. Under nitrogen protection, the second reaction vessel was heated to 80°C to allow the biochar particles to be fully impregnated and uniformly dispersed. The temperature was then raised to 125°C to initiate a hydrothermal reaction, which was carried out for 12 hours. This hydrothermal reaction process facilitates the directional growth and firm anchoring of metal oxide / hydroxide nanocrystals on the biochar surface. After the hydrothermal reaction, the mixture was allowed to cool naturally, filtered to obtain a solid product, and washed with deionized water until neutral. The solid product was then dried at 105°C for 85 minutes to obtain the modified biochar catalyst. This modified biochar catalyst has a rough and porous surface, exhibiting good water absorption and ion exchange capabilities. Furthermore, the modified biochar catalyst has a compressive strength of 3.5 MPa and a specific surface area of ​​175.5 m². 2 / g, with a metal loading rate of 5.5% (measured by weight); in addition, this modified biochar catalyst has good physical properties and can effectively convert ozone into hydroxyl radicals during ozone catalytic oxidation treatment, which can effectively degrade and adsorb organic matter in wastewater, thereby efficiently and stably reducing the permanganate index in wastewater.

[0061] Then, the primary treated liquid is transported to a modified activated carbon adsorption tower 22 equipped with modified activated carbon packing material via a secondary inlet pump 21 for adsorption treatment. The volume of the modified activated carbon packing material occupies 80% of the effective volume of the modified activated carbon adsorption tower 22, and the flow rate of the primary treated liquid in the modified activated carbon adsorption tower 22 is 6.3 m / h. After adsorption treatment in the modified activated carbon adsorption tower 22, the resulting secondary treated liquid is discharged via an outlet pump 23. Specifically, the pH value of the secondary treated liquid is approximately 7.2, and the permanganate index is approximately 2.5 mg / L, which meets the Class III standard requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0062] More specifically, in this example, the modified activated carbon filler is prepared by the following steps: selecting a specific surface area of ​​880 m². 2 / g of coal-based crushed activated carbon, 100-mesh fluidized bed coal gasification slag, and 100-mesh non-self-igniting coal gangue; wherein, the fluidized bed coal gasification slag is coal gasification slag taken from the fluidized bed gasification process, which has a porous structure and high residual carbon content, which is beneficial for preparing adsorption materials; the main components of the non-self-igniting coal gangue are aluminosilicate minerals such as kaolinite and illite. Then, the gasification slag from the fluidized bed coal gasification process and the non-self-igniting coal gangue were rinsed three times with clean water to remove soluble salts. Afterward, they were dried at 105°C for 12 hours. A 2.2 mol / L hydrochloric acid solution was prepared, and the gasification slag from the fluidized bed coal gasification process and the non-self-igniting coal gangue were mixed at a volume ratio of 3:1 to obtain a solid mixture. The solid mixture was then immersed in the hydrochloric acid solution at a solid-liquid ratio of 1 g:6 mL and stirred at 120 rpm for 48 minutes. The acid washing process removes some metal oxides and also expands the pores and increases the volume, resulting in an acid-treated mixture. This acid-treated mixture was then filtered, washed with water until neutral, and dried at 110°C to obtain a pretreated mixture. Next, the mixture was added at a mass ratio of 2:1... The pretreated mixture is mixed with the coal-based crushed activated carbon, and deionized water is added as a binder. The mixture is stirred in a mixer at 65 rpm for 12 minutes to obtain a plastic mixture. This mixture is then granulated in an extrusion granulator to obtain cylindrical particles with a diameter of 2.0 mm. The granules are then placed in a muffle furnace and preheated at 75°C for 50 minutes. The temperature is then increased to 386°C at a rate of 3°C / min and held for 47 minutes to remove organic matter. The temperature is then increased to 560°C at a rate of 6°C / min and held for 36 minutes to further stabilize the aluminosilicate minerals in the non-self-igniting coal gangue and the residual carbon in the gasification slag of the fluidized bed coal gasification process, forming a stable composite structure. The mixture is then cooled in the furnace to obtain the modified activated carbon filler. The modified activated carbon filler has a particle size of 2.0 mm and a specific surface area of ​​911.2 m². 2 / g, with a maximum adsorption capacity of 58.6mg / g for organic matter.

[0063] Example 2: The water quality characteristics of the stainless steel wastewater to be treated are: pH value approximately 7.5, permanganate index approximately 46 mg / L. The treatment steps for this stainless steel wastewater are as follows:

[0064] First, the stainless steel wastewater to be treated is pumped to an ozone catalytic tower 12 equipped with a modified biochar catalyst via a primary inlet pump 11. The wastewater enters the tower from the bottom and flows out from the top. An ozone generator 13, which is also an oxygen source generator, is connected to the ozone catalytic tower 12. The generated ozone also enters the tower from the bottom and fills the entire tower. The ozone concentration in the ozone catalytic tower 12 is 90 mg / L, and the ozone utilization rate is 92%. The modified biochar catalyst occupies 83% of the effective volume of the ozone catalytic tower 12, and the flow velocity of the stainless steel wastewater in the tower is 5.5 m / h. After ozone catalytic oxidation treatment in the ozone catalytic tower 12, a primary treated liquid is obtained, with a permanganate index of 10 mg / L.

[0065] Specifically, in this example, the modified biochar catalyst is prepared through the following steps: First, cotton stalks are selected as the biochar raw material, rinsed three times with clean water, and a 45% phosphoric acid solution is prepared. The cotton stalks are soaked in the phosphoric acid solution for 101 minutes, removed and dried, and then placed in a 105°C oven for 125 minutes. After natural cooling, pretreated cotton stalks are obtained. Next, the pretreated cotton stalks are placed in a muffle furnace and heated to 530°C at a heating rate of 6°C / min under nitrogen protection. This temperature is maintained for 60 minutes, and after natural cooling, cotton stalk biochar is obtained. The cotton stalk biochar is then ground into a fine powder using a grinder. 200-mesh cotton stalk biochar powder was selected; then, 200-mesh bentonite was selected as an inorganic binder, and the bentonite and cotton stalk biochar powder were mixed at a mass ratio of 1:4 to obtain a mixture. The mixture was added to a twin-shaft mixer and premixed at a rate of 90 rpm for 3 minutes. Deionized water was then slowly sprayed in, and the total moisture content was controlled to be 15% (on a wet basis). The mixture was then placed in a sealed first reaction vessel, which was kept at a constant temperature of 56°C and stirred at a stirring speed of 90 rpm for 38 minutes. The mixture was then cooled to obtain a cooled mixture. Finally, the cooled mixture was placed in a twin-screw extruder for granulation. The granulation process is carried out using a twin-screw extrusion granulator. The screw speed is 110 rpm, and the die temperature is 225°C. The high temperature induces slight thermoplasticity in the biochar-bentonite composite system, significantly improving particle density and compressive strength. The die is a circular die with a 2.0 mm aperture, and the extrusion pressure is 11 MPa, ensuring a uniform particle structure without voids, thus producing biochar particles with a diameter of 2.0 mm. Next, a 0.5 mol / L cobalt nitrate solution and a 0.6 mol / L nickel nitrate solution are prepared and mixed at a volume ratio of 3:1 to obtain a mixed solution. Then, the mixed solution... The mixed solution was placed in a second reaction vessel, and the biochar particles were added to the mixed solution at a liquid-to-solid ratio of 8 mL:1 g. Under nitrogen protection, the second reaction vessel was heated to 82°C to allow the biochar particles to be fully wetted and uniformly dispersed. The temperature was then raised to 135°C to initiate a hydrothermal reaction, which was carried out for 14 hours. This hydrothermal reaction process facilitates the directional growth and firm anchoring of metal oxide / hydroxide nanocrystals on the biochar surface. After the hydrothermal reaction, the mixture was allowed to cool naturally, filtered to obtain a solid product, and washed with deionized water until neutral. The solid product was then dried at 105°C for 100 minutes to obtain the modified biochar catalyst. This modified biochar catalyst has a rough and porous surface, exhibiting good water absorption and ion exchange capabilities. Furthermore, the modified biochar catalyst has a compressive strength of 4.5 MPa and a specific surface area of ​​181.5 m². 2 / g, with a metal loading rate of 6.0% (measured by weight); in addition, this modified biochar catalyst has good physical properties and can effectively convert ozone into hydroxyl radicals during ozone catalytic oxidation treatment, which can effectively degrade and adsorb organic matter in wastewater, thereby efficiently and stably reducing the permanganate index in wastewater.

[0066] Then, the primary treated liquid is transported to a modified activated carbon adsorption tower 22 equipped with modified activated carbon packing material via a secondary inlet pump 21 for adsorption treatment. The volume of the modified activated carbon packing material occupies 85% of the effective volume of the modified activated carbon adsorption tower 22, and the flow rate of the primary treated liquid in the modified activated carbon adsorption tower 22 is 7 m / h. After adsorption treatment in the modified activated carbon adsorption tower 22, the resulting secondary treated liquid is discharged via an outlet pump 23. Specifically, the pH value of the secondary treated liquid is approximately 7.5, and the permanganate index is approximately 3.6 mg / L, which meets the Class III standard requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0067] More specifically, in this example, the modified activated carbon filler is prepared by the following steps: selecting a specific surface area of ​​950 m². 2 / g of coal-based crushed activated carbon, 200-mesh fluidized bed coal gasification slag, and 200-mesh non-self-igniting coal gangue; wherein, the fluidized bed coal gasification slag is coal gasification slag taken from the fluidized bed gasification process, which has a porous structure and high residual carbon content, which is beneficial for preparing adsorption materials; the main components of the non-self-igniting coal gangue are aluminosilicate minerals such as kaolinite and illite. Then, the gasified coal gasification slag and the non-self-burning coal gangue were rinsed three times with clean water to remove soluble salts. Afterwards, they were dried at 105°C for 12 hours. A 2.3 mol / L hydrochloric acid solution was prepared, and the gasified coal gasification slag and the non-self-burning coal gangue were mixed at a volume ratio of 4:1 to obtain a solid mixture. The solid mixture was then immersed in the hydrochloric acid solution at a solid-liquid ratio of 1 g:7 mL and stirred at 130 rpm for 55 minutes. The acid washing process removes some metal oxides and also expands the pores and increases the volume. The resulting acid-treated mixture was filtered, washed with water until neutral, and dried at 110°C to obtain a pretreated mixture. Next, the mixture was prepared at a mass ratio of 3:1. The pretreated mixture is mixed with the coal-based crushed activated carbon, and deionized water is added as a binder. The mixture is stirred in a mixer at 75 rpm for 14 minutes to obtain a plastic mixture. This mixture is then granulated in an extrusion granulator to obtain cylindrical particles with a diameter of 2.0 mm. The granules are then placed in a muffle furnace and preheated at 77°C for 55 minutes. The temperature is then increased to 390°C at a rate of 5°C / min and held for 55 minutes to remove organic matter. The temperature is then increased to 565°C at a rate of 8°C / min and held for 45 minutes to further stabilize the aluminosilicate minerals in the non-self-igniting coal gangue and the residual carbon in the gasification slag of the fluidized bed coal gasification process, forming a stable composite structure. The mixture is then cooled in the furnace to obtain the modified activated carbon filler. The modified activated carbon filler has a particle size of 2.0 mm and a specific surface area of ​​1025.6 m². 2 / g, with a maximum adsorption capacity of 63.5mg / g for organic matter.

[0068] Example 2

[0069] This embodiment provides a deep treatment system for permanganate index of stainless steel wastewater. For details, please refer to [link to documentation]. Figure 3 , Figure 3 This is a structural block diagram of the stainless steel wastewater permanganate index deep treatment system provided in this embodiment. From... Figure 3As can be seen, the system includes an ozone catalytic oxidation unit 1 and an adsorption unit 2 arranged in sequence; the ozone catalytic oxidation unit 1 includes a primary inlet pump 11 and an ozone catalytic tower 12 connected in sequence, and an ozone generator 13 connected to the ozone catalytic tower 12, wherein the ozone catalytic tower 12 is provided with a modified biochar catalyst; the adsorption unit 2 includes a secondary inlet pump 21, a modified activated carbon adsorption tower 22 and an outlet pump 23 connected in sequence, wherein the inlet end of the secondary inlet pump 21 is connected to the outlet end of the ozone catalytic tower 12, and the modified activated carbon adsorption tower 22 is provided with modified activated carbon packing; the primary inlet pump 11 is configured to transport the stainless steel wastewater to be treated to the ozone catalytic tower 12. The system includes an ozone generator 13 configured to supply ozone to the ozone catalytic tower 12; the ozone catalytic tower 12 configured to receive the stainless steel wastewater to be treated and the ozone, and to cause the stainless steel wastewater to be treated, the modified biochar catalyst, and the ozone to undergo an ozone catalytic oxidation reaction in the ozone catalytic tower 12 to obtain a primary treated liquid; a secondary inlet pump 21 configured to transport the primary treated liquid to the modified activated carbon adsorption tower 22; the modified activated carbon adsorption tower 22 configured to adsorb the primary treated liquid using the modified activated carbon packing to obtain a secondary treated liquid; and an outlet pump 23 configured to discharge the secondary treated liquid.

[0070] It should be noted that the preparation steps of the modified biochar catalyst in this embodiment are the same as those of the modified biochar catalyst in Example 1 above, and the preparation steps of the modified activated carbon packing in this embodiment are the same as those of the modified activated carbon packing in Example 1 above, and will not be repeated here.

[0071] Since the stainless steel wastewater permanganate index deep treatment system provided in this embodiment belongs to the same inventive concept as the stainless steel wastewater permanganate index deep treatment method described in any of the above embodiments, the stainless steel wastewater permanganate index deep treatment system provided in this embodiment has at least all the advantages of the stainless steel wastewater permanganate index deep treatment methods provided in the above embodiments. For details regarding the advantages of the stainless steel wastewater permanganate index deep treatment system provided in this embodiment, please refer to the relevant descriptions of the beneficial effects of the stainless steel wastewater permanganate index deep treatment methods provided in the above embodiments, which will not be repeated here. Furthermore, the stainless steel wastewater permanganate index deep treatment system provided in this embodiment has stable treatment effect, low production and operating costs, simple operation, and a high degree of automation, making it an environmentally friendly wastewater treatment system.

[0072] In summary, the deep treatment method and system for permanganate index of stainless steel wastewater provided by this invention has the following advantages: The deep treatment method for permanganate index of stainless steel wastewater provided by this invention includes: conveying the stainless steel wastewater to be treated to an ozone catalytic tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treated liquid; and conveying the primary treated liquid to a modified activated carbon adsorption tower equipped with modified activated carbon packing for adsorption treatment to obtain a secondary treated liquid. Therefore, the deep treatment method for permanganate index of stainless steel wastewater provided by this invention, by conveying the stainless steel wastewater to be treated to an ozone catalytic tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment, utilizes the modified biochar catalyst, which has a rough and porous surface, exhibiting good water absorption and ion exchange capacity, and possessing good physical properties. During the ozone catalytic oxidation treatment process, it can effectively convert ozone into hydroxyl radicals, effectively degrading and adsorbing organic matter in the wastewater, and efficiently and stably reducing the permanganate index of the wastewater. Furthermore, by conveying the primary treated liquid to a modified activated carbon adsorption tower equipped with modified activated carbon packing material for adsorption treatment, the modified activated carbon packing material, with its large specific surface area and high adsorption capacity for organic matter, can further reduce the permanganate index in the primary treated liquid. Finally, by employing the deep treatment method for permanganate index in stainless steel wastewater provided by this invention, specific treatment of the permanganate index can be achieved, realizing efficient and stable reduction of the permanganate index in wastewater, ensuring that the permanganate index in the effluent consistently meets the Class III standard requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0073] Since the stainless steel wastewater permanganate index deep treatment system provided by this invention belongs to the same inventive concept as the stainless steel wastewater permanganate index deep treatment method described in any of the above claims, the stainless steel wastewater permanganate index deep treatment system provided by this invention has at least all the advantages of the stainless steel wastewater permanganate index deep treatment method provided by this invention. For the advantages of the stainless steel wastewater permanganate index deep treatment system provided by this invention, please refer to the relevant description of the beneficial effects of the stainless steel wastewater permanganate index deep treatment method provided by this invention, which will not be repeated here.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for deep treatment of permanganate index in stainless steel wastewater, characterized in that, include: The stainless steel wastewater to be treated is transported to an ozone catalytic tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treated liquid. The primary treated liquid is transported to a modified activated carbon adsorption tower equipped with modified activated carbon packing for adsorption treatment to obtain a secondary treated liquid.

2. The method for deep treatment of permanganate index in stainless steel wastewater as described in claim 1, characterized in that, The water quality of the stainless steel wastewater to be treated is as follows: pH value of 6-9, permanganate index of 32mg / L-49mg / L.

3. The method for deep treatment of permanganate index in stainless steel wastewater as described in claim 1, characterized in that, The process involves conveying the stainless steel wastewater to an ozone catalytic tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment, yielding a primary treated liquid, comprising: The stainless steel wastewater to be treated is pumped to an ozone catalytic tower equipped with a modified biochar catalyst via a primary inlet pump. Ozone is supplied to the ozone catalytic tower via an ozone generator, so that the stainless steel wastewater to be treated, the modified biochar catalyst, and the ozone undergo an ozone catalytic oxidation reaction in the ozone catalytic tower to obtain the primary treated liquid.

4. The method for deep treatment of permanganate index in stainless steel wastewater as described in claim 1, characterized in that, In the ozone catalytic tower, the ozone inlet concentration is 75 mg / L to 93 mg / L, and the ozone utilization rate is 89% to 93%.

5. The method for deep treatment of permanganate index in stainless steel wastewater as described in claim 1, characterized in that, The modified biochar catalyst is packed in a volume that accounts for 80% to 85% of the effective volume of the ozone catalytic tower, and the flow rate of the stainless steel wastewater to be treated in the ozone catalytic tower is 4.3 m / h to 5.8 m / h.

6. The method for deep treatment of permanganate index in stainless steel wastewater as described in claim 1, characterized in that, The modified biochar catalyst was prepared through the following steps: Cotton stalks were selected as the raw material for biochar. They were rinsed with water 2 to 3 times and a phosphoric acid solution with a concentration of 32% to 47% was prepared. The cotton stalks were soaked in the phosphoric acid solution for 67 minutes to 112 minutes, taken out and dried, and then placed in an oven at 105°C for 65 minutes to 145 minutes. After natural cooling, the pretreated cotton stalks were obtained. The pretreated cotton stalks were placed in a muffle furnace and heated to 520°C to 535°C at a heating rate of 4°C to 7°C per minute under nitrogen protection. The temperature was then maintained for 45 to 65 minutes and allowed to cool naturally to obtain cotton stalk biochar. The cotton stalk biochar was then ground to obtain 100-200 mesh fine powder. Bentonite of 100-200 mesh was selected as an inorganic binder. The bentonite was mixed with the cotton stalk biochar powder at a mass ratio of 1:(3-4). The mixture was added to a twin-shaft mixer and premixed at a speed of 75-95 rpm for 2-3 minutes. Deionized water was then sprayed in, and the total water content was controlled to be 12%-15%. The mixture was then placed in a first reaction vessel, which was kept at a constant temperature of 53-56°C and stirred at a speed of 75-95 rpm for 35-40 minutes. The mixture was then cooled to obtain a cooled mixture. The cooled mixture is fed into a twin-screw extruder for granulation. In the twin-screw extruder, the screw speed is 95 rpm to 115 rpm, the die temperature is 215°C to 225°C, and the extrusion pressure is 9.3 MPa to 11.2 MPa to obtain biochar granules. Prepare a cobalt nitrate solution with a concentration of 0.2 mol / L to 0.5 mol / L and a nickel nitrate solution with a concentration of 0.2 mol / L to 0.7 mol / L. Mix the cobalt nitrate solution and the nickel nitrate solution at a volume ratio of (2~3):1 to obtain a mixed solution. The mixed solution was placed in a second reaction vessel, and the biochar particles were added to the mixed solution at a liquid-to-solid ratio of (6~8) mL: 1 g. Under nitrogen protection, the second reaction vessel was heated to 78℃~83℃, then heated to 125℃~135℃ and hydrothermally reacted for 10~15 hours. After natural cooling, the solid product was obtained by filtration. The solid product was washed with deionized water until neutral and then dried at 105℃ for 75 minutes~105 minutes to obtain the modified biochar catalyst. The modified biochar catalyst has a compressive strength of 3.5 MPa to 4.5 MPa and a specific surface area of ​​167.1 m². 2 / g~187.6m 2 / g, with a metal loading rate of 5.1%~6.3%.

7. The method for deep treatment of permanganate index of stainless steel wastewater as described in claim 1, characterized in that, The modified activated carbon filler is prepared by the following steps: Select a specific surface area of ​​850m² 2 / g~960m 2 / g of coal-based crushed activated carbon, fluidized bed coal gasification slag with a particle size of 100-200 mesh, and non-self-combusting coal gangue with a particle size of 100-200 mesh; After rinsing the gasified coal gasification slag and the non-self-igniting coal gangue 2 to 3 times with clean water, dry them at 105°C for 12 hours. Prepare a hydrochloric acid solution with a concentration of 2.1 mol / L to 2.6 mol / L. Mix the gasified coal gasification slag and the non-self-igniting coal gangue at a volume ratio of (2 to 4):1 to obtain a solid mixture. Soak the solid mixture in the hydrochloric acid solution at a solid-liquid ratio of 1 g to (4 to 7) mL and stir at a stirring speed of 115 rpm to 135 rpm for 45 to 55 minutes to obtain an acid-treated mixture. Filter the acid-treated mixture, wash it with water until neutral, and dry it at 110°C to obtain a pretreated mixture. The pretreated mixture is mixed with the coal-based crushed activated carbon at a mass ratio of (2~3):1, and deionized water is added as a binder. The mixture is stirred in a mixer at a stirring speed of 65 rpm to 75 rpm for 10 to 15 minutes to obtain a mixture. The mixture is then placed into an extrusion granulator for granulation to obtain granular products. The granular product is placed in a muffle furnace and preheated at 75°C to 80°C for 50 to 55 minutes. Then, the temperature is increased to 385°C to 393°C at a heating rate of 3°C / min to 5°C / min and held for 45 to 55 minutes. Next, the temperature is increased to 555°C to 565°C at a heating rate of 6°C / min to 8°C / min and held for 35 to 45 minutes. After cooling, the modified activated carbon filler is obtained.

8. The method for deep treatment of permanganate index in stainless steel wastewater as described in claim 1, characterized in that, The specific surface area of ​​the modified activated carbon filler is 895.1 m². 2 / g~1078.3m 2 / g, with a maximum adsorption capacity of 56.2mg / g to 64.1mg / g for organic matter.

9. The method for deep treatment of permanganate index of stainless steel wastewater as described in claim 1, characterized in that, The modified activated carbon packing material occupies 80% to 85% of the effective volume of the modified activated carbon adsorption tower, and the flow rate of the primary treatment liquid in the modified activated carbon adsorption tower is 6 m / h to 7 m / h.

10. A deep treatment system for permanganate index of stainless steel wastewater, characterized in that, The system includes an ozone catalytic oxidation unit and an adsorption unit arranged sequentially. The ozone catalytic oxidation unit includes a primary water pump and an ozone catalytic tower connected in sequence, and an ozone generator connected to the ozone catalytic tower. The ozone catalytic tower is equipped with a modified biochar catalyst. The adsorption unit includes a secondary water inlet pump, a modified activated carbon adsorption tower, and an outlet pump connected in sequence. The inlet end of the secondary water inlet pump is connected to the outlet end of the ozone catalytic tower. The modified activated carbon adsorption tower is equipped with modified activated carbon packing. The primary inlet pump is configured to transport the stainless steel wastewater to be treated to the ozone catalytic tower. The ozone generator is configured to supply ozone to the ozone catalytic tower; The ozone catalytic tower is configured to receive the stainless steel wastewater to be treated and the ozone, and to cause the stainless steel wastewater to be treated, the modified biochar catalyst and the ozone to undergo an ozone catalytic oxidation reaction in the ozone catalytic tower to obtain a primary treated liquid. The secondary inlet pump is configured to transport the primary treated liquid to the modified activated carbon adsorption tower; The modified activated carbon adsorption tower is configured to use the modified activated carbon packing to adsorb the primary treatment liquid to obtain a secondary treatment liquid. The water pump is configured to discharge the secondary treated liquid.

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