Method and system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water

Abstract

The application provides a method and system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water, which comprises the following steps: using a compound oxidizing coagulant to coagulate and precipitate the coking reverse osmosis concentrated water to obtain a first treatment liquid; and conveying the first treatment liquid to an ozone catalytic oxidation tower provided with a modified water slag catalyst to perform ozone catalytic oxidation treatment, thereby obtaining a second treatment liquid. The method and system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water can preliminarily remove benzofluoranthene and perfluoroalkyl compounds and other refractory organic matters in the coking reverse osmosis concentrated water through coagulation and precipitation treatment, thereby improving the effect of subsequent ozone catalytic oxidation treatment. Further ozone catalytic oxidation treatment of the coking reverse osmosis concentrated water can further remove benzofluoranthene and perfluoroalkyl compounds and other refractory organic matters in the coking reverse osmosis concentrated water, thereby reducing environmental pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, in particular to a method and system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water. Background Art

[0002] Coking wastewater is a highly concentrated and complex industrial wastewater containing a variety of inorganic and organic pollutants, including chemical oxygen demand (COD), ammonia nitrogen, thiocyanate, phenols, aniline, and benzofluoranthene. Benzofluoranthene is a typical non-biodegradable organic compound, while perfluoroalkyl compounds, due to their high stability and bioaccumulation, pose a serious threat to the environment and human health.

[0003] Reverse osmosis technology is widely used in the treatment of coking wastewater due to its excellent desalination performance and low energy consumption. However, its application produces large amounts of brine, which not only contains high concentrations of salt but also contains a variety of difficult-to-degrade organic compounds, including benzofluoranthene and perfluoroalkyl compounds. These organic compounds are extremely toxic and stable, making them difficult to effectively remove using traditional biological treatment methods, posing a serious threat to the environment and ecosystems. Summary of the Invention

[0004] The object of the present invention is to provide a method and system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrate, so as to solve one or more problems existing in the prior art, such as the difficulty in effectively removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrate by traditional biological treatment methods and the serious threat they pose to the environment and ecosystem.

[0005] To achieve the above object, the present invention is implemented by the following technical solution: a method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water, comprising:

[0006] Using a composite oxidizing coagulant to perform coagulation and sedimentation treatment on the coking reverse osmosis concentrated water to obtain a primary treated liquid;

[0007] The primary treatment liquid is transported to an ozone catalytic oxidation tower equipped with a modified water slag catalyst for ozone catalytic oxidation treatment to obtain a secondary treatment liquid.

[0008] Optionally, the water quality of the coking reverse osmosis concentrated water before treatment is: benzofluoranthene concentration is 34.1 μg / L to 56.5 μg / L, and perfluoroalkyl compound concentration is 821 ng / L to 1785 ng / L.

[0009] Optionally, the coking reverse osmosis concentrate is subjected to coagulation and sedimentation treatment using a compound oxidizing coagulant to obtain a primary treatment liquid, comprising: transporting the coking reverse osmosis concentrate to a coagulation and sedimentation tank; adding the compound oxidizing coagulant to the coagulation and sedimentation tank so that the coking reverse osmosis concentrate and the compound oxidizing coagulant undergo a coagulation and sedimentation reaction in the coagulation and sedimentation tank to obtain the primary treatment liquid.

[0010] Optionally, 234 mL to 356 mL of the composite oxidizing coagulant is added to each ton of the coking reverse osmosis concentrated water.

[0011] Optionally, the composite oxidizing coagulant is prepared by the following steps: SA1: selecting a particle size of 100-300 mesh and a specific surface area of ​​14.2 m 2 / g~26.1m 2 / g of diatomaceous earth; SA2: mixing the diatomaceous earth, potassium ferrate and potassium permanganate in a mass ratio of (9-15):4:3, conveying the mixture to a mixer and grinding for 25 minutes to 37 minutes to obtain a mixed powder; SA3: placing the mixed powder in a heating device and heating it to 42°C to 47°C, maintaining it at this temperature for 72 minutes to 89 minutes, and then cooling it to room temperature to obtain a mixed solid; SA4: preparing a ferric chloride solution with a concentration of 234 mg / L to 303 mg / L, adding 0.7 g to 1.5 g of the mixed solid to each liter of the ferric chloride solution, and stirring at a stirring speed of 40 rpm to 55 rpm for 21 minutes to 34 minutes to obtain the composite oxidizing coagulant.

[0012] Optionally, the modified water slag catalyst is prepared by the following steps: SB1: selecting water slag with a particle size of 1.5 mm to 3.2 mm; SB2: soaking the water slag in a hydrochloric acid solution with a mass fraction of 2.3% to 4.6% for 67 minutes to 89 minutes, taking it out and placing it in a drying device for drying for 95 minutes to 135 minutes, and then cooling it to room temperature; SB3: preparing a mixed solution of the water slag, ferric chloride, copper chloride and pure water in a volume ratio of (6 to 7):2:3:(60 to 80) and placing it in a reaction vessel, adding 1 mL to 3 mL of dioxane and 0.2 g to 0.5 g of chloromethylated polystyrene to each liter of the mixed solution; SB4: heating the reaction vessel to 175°C to 197°C, maintaining it at this temperature for 125 minutes to 176 minutes, cooling the mixed solution to room temperature and filtering it to obtain the modified water slag catalyst.

[0013] Optionally, the volume ratio of the modified water slag catalyst to the ozone catalytic oxidation tower is 75% to 85%; and the residence time of the primary treatment liquid in the ozone catalytic oxidation tower is 37 minutes to 46 minutes.

[0014] Optionally, the ratio of the height to the diameter of the ozone catalytic oxidation tower is 4:1.

[0015] Optionally, the water quality of the secondary treatment liquid is: the concentration of benzofluoranthene is 14.2 μg / L to 21.1 μg / L, and the concentration of perfluoroalkyl compounds is 234 ng / L to 511 ng / L.

[0016] To achieve the above-mentioned objectives, the present invention also provides a system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water, comprising a coagulation and sedimentation module and an ozone catalytic oxidation module arranged in sequence; the coagulation and sedimentation module is configured to use a compound oxidizing coagulant to perform coagulation and sedimentation treatment on the coking reverse osmosis concentrated water to obtain a primary treatment liquid; the ozone catalytic oxidation module is configured to transport the primary treatment liquid to an ozone catalytic oxidation tower equipped with a modified water slag catalyst for ozone catalytic oxidation treatment to obtain a secondary treatment liquid.

[0017] Compared with the prior art, the method and system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided by the present invention have the following beneficial effects:

[0018] The method provided by the present invention for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water comprises: using a composite oxidizing coagulant to perform coagulation and sedimentation treatment on the coking reverse osmosis concentrated water to obtain a primary treatment liquid; and transporting the primary treatment liquid to an ozone catalytic oxidation tower equipped with a modified water slag catalyst to perform ozone catalytic oxidation treatment to obtain a secondary treatment liquid. Thus, the method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided by the present invention is to perform coagulation and precipitation treatment on the coking reverse osmosis concentrated water by using a composite oxidizing coagulant, wherein the oxidant in the composite oxidizing coagulant (exemplarily, including but not limited to potassium ferrate and potassium permanganate) can produce a strong oxidizing substance to decompose the benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic matter in the coking reverse osmosis concentrated water, and the coagulant in the composite oxidizing coagulant (exemplarily, including but not limited to ferric chloride solution) can increase the sedimentation rate and efficiency of the suspended matter, and under the synergistic effect of oxidation and coagulation of the composite oxidizing coagulant, the removal effect of difficult-to-degrade organic matter such as benzofluoranthene and perfluoroalkyl compounds in the coking reverse osmosis concentrated water can be improved. Then, by transporting the primary treatment liquid to an ozone catalytic oxidation tower provided with a modified water slag catalyst for ozone catalytic oxidation treatment, the ozone catalytic oxidation efficiency of the primary treatment liquid can be improved, thereby further improving the removal effect of difficult-to-degrade organic matter such as benzofluoranthene and perfluoroalkyl compounds in the coking reverse osmosis concentrated water. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided by the present invention can effectively remove benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic substances from the coking reverse osmosis concentrated water, thereby reducing environmental pollution.

[0019] Since the system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided by the present invention belongs to the same inventive concept as the method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water described in any of the above-mentioned items, the system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided by the present invention has at least all the advantages of the method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided by the present invention. For the advantages of the system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided by the present invention, please refer to the relevant description of the beneficial effects of the method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided by the present invention, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the overall steps of a method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided in Example 1 of the present invention;

[0021] Figure 2 A schematic diagram of a specific process of a method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided in Example 1 of the present invention;

[0022] Figure 3 This is a structural block diagram of a system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided in Example 2 of the present invention;

[0023] The following are the descriptions of the reference numerals:

[0024] 1-coagulation and sedimentation module, 11-first-stage water inlet pump, 12-coagulation and sedimentation tank, 13-dosing device, 2-ozone catalytic oxidation module, 21-secondary water inlet pump, 22-ozone catalytic oxidation tower, 23-drainage pump. DETAILED DESCRIPTION

[0025] The method and system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present application will be further described in detail below in combination with the accompanying drawings and specific embodiments. The advantages and features of the present application will be more apparent according to the following description. It should be noted that the accompanying drawings are very simplified and non-precise in proportion, and are only used for the purpose of facilitating and clarifying the description of the embodiments of the present application. For the purpose of making the purposes, features and advantages of the present application more apparent and easy to understand, please refer to the accompanying drawings. It should be understood that the structures, proportions, sizes, etc. shown in the drawings attached to the present specification are only used to cooperate with the content disclosed in the specification, so that those skilled in the art can understand and read, and are not used to limit the implementation of the present application. Any modification of structure, change of proportion relationship or adjustment of size, as long as it is the same or similar to the effect and purpose that can be achieved by the present application, should still fall within the scope of the technical content disclosed by the present application. The specific design features of the present application disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific application and use environment. In addition, in the following description of the embodiments, the same reference numerals are sometimes used in different drawings to represent the same parts or parts with the same function, and the repeated description is omitted.

[0026] It should be understood that, unless specifically stated or apparent from the context, as used herein, the term "about" is understood to be within normal tolerances in the art, for example within 2 standard deviations of the mean. "About" can be understood to be 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 explicitly from the context, all numerical values provided herein are modified by the term "about".

[0027] Example One

[0028] The present embodiment provides a method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water. Specifically, please refer to Figure 1 and Figure 2 , Figure 1 The general step schematic diagram of the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present embodiment is shown in Figure 2 The specific flow schematic diagram of the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present embodiment is shown in Figure 1 and Figure 2 It can be seen that the method comprises:

[0029] S100: coagulation and sedimentation treatment is performed on the coking reverse osmosis concentrated water using a compounded oxidation coagulant to obtain a primary treatment liquid;

[0030] S200: The primary treatment liquid is transported to an ozone catalytic oxidation tower 22 equipped with a modified water slag catalyst for ozone catalytic oxidation treatment to obtain a secondary treatment liquid.

[0031] Thus, the method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided in this embodiment is to perform coagulation and sedimentation treatment on the coking reverse osmosis concentrated water by using a composite oxidizing coagulant. The oxidant in the composite oxidizing coagulant (exemplarily including but not limited to potassium ferrate and potassium permanganate) can produce a strong oxidizing substance to decompose the benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic matter in the coking reverse osmosis concentrated water. The coagulant in the composite oxidizing coagulant (exemplarily including but not limited to ferric chloride solution) can increase the sedimentation rate and efficiency of the suspended matter. Under the synergistic effect of the oxidation and coagulation of the composite oxidizing coagulant, the removal effect of the benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic matter in the coking reverse osmosis concentrated water can be improved. Then, by transporting the primary treatment liquid to an ozone catalytic oxidation tower 22 equipped with a modified water slag catalyst for ozone catalytic oxidation treatment, the ozone catalytic oxidation efficiency of the primary treatment liquid can be improved, thereby further improving the removal effect of the benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic matter in the coking reverse osmosis concentrated water. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided by the present invention can effectively remove benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic substances from the coking reverse osmosis concentrated water, thereby reducing environmental pollution.

[0032] For example, in some exemplary embodiments, the water quality characteristics of the coking reverse osmosis concentrated water before treatment can be: TDS (Total dissolved solids) is about 23345 mg / L ~ 34678 mg / L, suspended matter concentration is about 89 mg / L ~ 139 mg / L, benzofluoranthene concentration is about 34.1 μg / L ~ 56.5 μg / L, and perfluoroalkyl compound concentration is about 821 ng / L ~ 1785 ng / L.

[0033] Preferably, the step S100 of using the compound oxidizing coagulant to coagulate and precipitate the coking reverse osmosis concentrated water to obtain a primary treatment liquid comprises: feeding the coking reverse osmosis concentrated water into a coagulation and precipitation tank 12; adding the compound oxidizing coagulant into the coagulation and precipitation tank 12, so that the coking reverse osmosis concentrated water and the compound oxidizing coagulant have a coagulation and precipitation reaction in the coagulation and precipitation tank 12 to obtain the primary treatment liquid. In this way, by adding the compound oxidizing coagulant into the coagulation and precipitation tank 12, the oxidizing agent (for example, including but not limited to potassium ferrate and potassium permanganate) in the compound oxidizing coagulant can produce a strong oxidizing substance to decompose the benzofluoranthene and perfluoroalkyl compounds and other refractory organic matters in the coking reverse osmosis concentrated water, and the coagulant (for example, including but not limited to ferric chloride solution) in the compound oxidizing coagulant can improve the settling speed and efficiency of the suspended solids, so that the removal effect of the benzofluoranthene and perfluoroalkyl compounds and other refractory organic matters in the coking reverse osmosis concentrated water can be improved under the synergistic effect of the oxidation and coagulation of the compound oxidizing coagulant.

[0034] For example, in some of the exemplary embodiments, the front part of the coagulation and precipitation tank 12 is a dosing and mixing zone (not shown in the figure), which is connected with a dosing device 13. The dosing device 13 adds the compound oxidizing coagulant into the dosing and mixing zone at a dosing ratio of about 234 mL to 356 mL of the compound oxidizing coagulant per ton of the coking reverse osmosis concentrated water. A stirring device (not shown in the figure) is arranged in the dosing and mixing zone, so that the coking reverse osmosis concentrated water and the compound oxidizing coagulant are fully mixed for 3.5 minutes to 6 minutes. In addition, the rear part of the coagulation and precipitation tank 12 is a precipitation zone (not shown in the figure), and the residence time of the coking reverse osmosis concentrated water in the precipitation zone is 17 minutes to 20 minutes.

[0035] For example, in some of the exemplary embodiments, the compound oxidizing coagulant is prepared by the following steps:

[0036] SA1: diatomite with a particle size of 100 mesh to 300 mesh and a specific surface area of 14.2 m 2 / g to 26.1 m 2 / g is selected;

[0037] SA2: the diatomite, potassium ferrate and potassium permanganate are mixed at a mass ratio of (9-15):4:3, and then fed into a mixer for grinding for 25 minutes to 37 minutes to obtain a mixed powder;

[0038] SA3: the mixed powder is placed into a heating device and heated to 42°C to 47°C, and then kept at this temperature for 72 minutes to 89 minutes, and then cooled to room temperature to obtain a mixed solid;

[0039] SA4: Prepare a ferric chloride solution with a concentration of 234 mg / L to 303 mg / L, add 0.7 g to 1.5 g of the mixed solid per liter of the ferric chloride solution, and stir at a stirring speed of 40 rpm to 55 rpm for 21 minutes to 34 minutes to obtain the composite oxidizing coagulant.

[0040] Thus, a composite oxidizing coagulant is prepared according to the above steps, which has better oxidation and coagulation effects, laying a good foundation for improving the removal of difficult-to-degrade organic matter such as benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrate. It should be noted that the parameters given in the preparation process of the above composite oxidizing coagulant are only exemplary and should be reasonably set according to the water quality characteristics of the coking reverse osmosis concentrate.

[0041] It should be noted that, as those skilled in the art will appreciate, the present invention does not impose any particular limitations on the type of heating device. For example, in some exemplary embodiments, the heating device may be a heating furnace that uses nitrogen as a protective atmosphere.

[0042] For example, in some exemplary embodiments, the water quality of the obtained primary treatment liquid is: a benzofluoranthene concentration of 24.3 μg / L to 39.1 μg / L, and a perfluoroalkyl compound concentration of 567 ng / L to 1103 ng / L.

[0043] Preferably, the modified water slag catalyst is prepared by the following steps:

[0044] SB1: Select water slag with a particle size of 1.5 mm to 3.2 mm;

[0045] SB2: Soaking the slag in a hydrochloric acid solution having a mass fraction of 2.3% to 4.6% for 67 to 89 minutes, removing the slag and placing it in a drying device for drying for 95 to 135 minutes, and then cooling it to room temperature;

[0046] SB3: preparing a mixed solution of the water slag, ferric chloride, copper chloride, and pure water in a volume ratio of (6-7):2:3:(60-80) and placing the solution in a reaction vessel. Adding 1 mL-3 mL of dioxane and 0.2 g-0.5 g of chloromethylated polystyrene per liter of the mixed solution;

[0047] SB4: The reaction vessel is heated to 175° C. to 197° C., and maintained at this temperature for 125 to 176 minutes, and then the mixed solution is cooled to room temperature and filtered to obtain the modified water slag catalyst.

[0048] Thus, a modified water-slag catalyst was prepared according to the above steps, resulting in a modified water-slag catalyst having superior catalytic performance, laying a good foundation for improving the removal of refractory organic matter, such as benzofluoranthene and perfluoroalkyl compounds, from coking reverse osmosis concentrate. It should be noted that the parameters given in the preparation of the modified water-slag catalyst are merely illustrative and should be appropriately set based on the water quality characteristics of the coking reverse osmosis concentrate.

[0049] It should be noted that, as those skilled in the art will appreciate, the present invention does not impose any particular limitations on the types of the drying device and the reaction vessel. For example, in some exemplary embodiments, the drying device may be a forced air drying oven with a set temperature of 115°C; and the reaction vessel may be an autoclave. Before heating, the autoclave is sealed and then filled with nitrogen to remove air, creating an oxygen-free protective atmosphere.

[0050] Furthermore, the volume ratio of the modified water-slag catalyst to the ozone catalytic oxidation tower 22 is 75% to 85%, and the residence time of the primary treatment liquid in the ozone catalytic oxidation tower 22 is 37 to 46 minutes. This significantly improves the treatment effect and operating efficiency of the ozone catalytic oxidation tower 22, thereby better removing difficult-to-degrade organic matter such as benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrate. Furthermore, it reduces the operating energy consumption and cost of the ozone catalytic oxidation tower 22.

[0051] Preferably, the ratio of the height to the diameter of the ozone catalytic oxidation tower 22 is 4: 1. This can further improve the treatment effect and operating efficiency of the ozone catalytic oxidation tower 22 and reduce the operating energy consumption and operating cost of the ozone catalytic oxidation tower 22.

[0052] For example, in some exemplary embodiments, the water quality of the obtained secondary treatment liquid is: a benzofluoranthene concentration of 14.2 μg / L to 21.1 μg / L, and a perfluoroalkyl compound concentration of 234 ng / L to 511 ng / L.

[0053] In order to facilitate understanding of the present invention, the process of treating coking reverse osmosis concentrated water by using the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided in this embodiment is described as an example.

[0054] In this example, the water quality characteristics of the coking reverse osmosis concentrated water are: TDS 23345mg / L to 34678mg / L, suspended solids concentration 89mg / L to 139mg / L, benzofluoranthene concentration 34.1μg / L to 56.5μg / L, and perfluoroalkyl compound concentration 821ng / L to 1785ng / L. The treatment steps for this coking reverse osmosis concentrated water are as follows:

[0055] First, the coking reverse osmosis concentrate is transported to the dosing and mixing zone of the coagulation and sedimentation tank 12 via the primary water inlet pump 11. Simultaneously, the dosing device 13 is controlled to add a composite oxidizing coagulant to the dosing and mixing zone at a dosage ratio of 234 mL to 356 mL per ton of the coking reverse osmosis concentrate. The coking reverse osmosis concentrate and the composite oxidizing coagulant are thoroughly mixed for 3.5 to 6 minutes. After the coking reverse osmosis concentrate remains in the sedimentation zone for 17 to 20 minutes, a primary treated liquid is obtained. Specifically, the primary treated liquid has a TDS of 23,345 mg / L to 34,678 mg / L, a suspended solids concentration of 7 mg / L to 17 mg / L, a benzofluoranthene concentration of 24.3 μg / L to 39.1 μg / L, and a perfluoroalkyl compound concentration of 567 ng / L to 1,103 ng / L.

[0056] Specifically, in this example, the composite oxidizing coagulant is prepared by the following steps: selecting a particle size of 100-300 mesh and a specific surface area of ​​14.2 m 2 / g~26.1m 2 / g of diatomaceous earth; after mixing diatomaceous earth, potassium ferrate and potassium permanganate in a mass ratio of (9-15):4:3, conveying the mixture to a mixer and grinding for 25 minutes to 37 minutes to obtain a mixed powder; then placing the mixed powder in a heating furnace, heating it to 42°C to 47°C under a protective atmosphere of nitrogen, and maintaining it at this temperature for 72 minutes to 89 minutes, and then cooling it to room temperature to obtain a mixed solid; then preparing a ferric chloride solution with a concentration of 234 mg / L to 303 mg / L, adding 0.7g to 1.5g of the mixed solid to each liter of the ferric chloride solution, and stirring at a stirring speed of 40 rpm to 55 rpm for 21 minutes to 34 minutes to obtain the composite oxidizing coagulant.

[0057] Then, the primary treatment liquid is transported to the ozone catalytic oxidation tower 22 equipped with a modified water slag catalyst via a secondary water inlet pump 21. The height-to-diameter ratio of the ozone catalytic oxidation tower 22 is 4:1, and the volume ratio of the modified water slag catalyst to the ozone catalytic oxidation tower 22 is 75% to 85%. After the primary treatment liquid remains in the ozone catalytic oxidation tower 22 for 37 to 46 minutes, a secondary treatment liquid is obtained, which is then discharged via a drainage pump 23. Specifically, the TDS of the secondary treatment liquid is 23345 mg / L to 34678 mg / L, the suspended solids concentration is 5 mg / L to 11 mg / L, the benzofluoranthene concentration is 14.2 μg / L to 21.1 μg / L, and the perfluoroalkyl compound concentration is 234 ng / L to 511 ng / L. It can be seen that the secondary treatment liquid meets the discharge standards or reuse requirements and can be directly discharged or transported to a near-zero discharge system for wastewater.

[0058] More specifically, in this example, the modified water slag catalyst is prepared by the following steps: selecting water slag with a particle size of 1.5 mm to 3.2 mm; and soaking the water slag in a hydrochloric acid solution with a mass fraction of 2.3% to 4.6% for 67 minutes to 89 minutes, taking it out and placing it in a blast drying furnace at 115°C for 95 minutes to 135 minutes, and then cooling it to room temperature; then, the water slag, ferric chloride, copper chloride and pure water are prepared into a mixed solution according to a volume ratio of (6 to 7):2:3:(60 to 80) and placed in an autoclave, and 1 mL to 3 mL of dioxane and 0.2 g to 0.5 g of chloromethylated polystyrene are added to each liter of the mixed solution; finally, the autoclave is sealed and filled with nitrogen and heated to 175°C to 197°C. After maintaining this temperature for 125 minutes to 176 minutes, the mixed solution is cooled to room temperature and filtered to obtain the modified water slag catalyst.

[0059] It can be seen that the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present invention is used to treat coking reverse osmosis concentrated water, which can efficiently remove difficult-to-degrade organic matter such as benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water, thereby effectively solving the problem of environmental pollution caused by coking reverse osmosis concentrated water.

[0060] To facilitate further understanding of the present invention, the present invention will be described below with two specific examples of treating coking reverse osmosis concentrated water using the method provided by the present invention for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water.

[0061] Example 1: The water quality characteristics of the coking reverse osmosis concentrated water are: TDS of 25649 mg / L, suspended solids concentration of 98 mg / L, benzofluoranthene concentration of 37.8 μg / L, and perfluoroalkyl compound concentration of 978 ng / L. The treatment steps for the coking reverse osmosis concentrated water are as follows:

[0062] First, the coking reverse osmosis concentrate was pumped to the dosing and mixing zone of the coagulation and sedimentation tank 12 via the primary water inlet pump 11. Simultaneously, the dosing device 13 was controlled to add a composite oxidizing coagulant to the dosing and mixing zone at a rate of 264 mL per ton of coking reverse osmosis concentrate. The coking reverse osmosis concentrate and the composite oxidizing coagulant were thoroughly mixed for 4.3 minutes. After the coking reverse osmosis concentrate remained in the sedimentation zone for 18 minutes, a primary treated liquid was obtained. Specifically, the primary treated liquid had a TDS of 25,517 mg / L, a suspended solids concentration of 12 mg / L, a benzofluoranthene concentration of 28.1 μg / L, and a perfluoroalkyl compound concentration of 694 ng / L.

[0063] Specifically, in this example, the composite oxidizing coagulant is prepared by the following steps: selecting a particle size of 120 mesh and a specific surface area of ​​21.3 m 2 / g of diatomaceous earth; diatomaceous earth, potassium ferrate and potassium permanganate are mixed in a mass ratio of 10:4:3, conveyed to a mixer and ground for 28 minutes to obtain a mixed powder; the mixed powder is then placed in a heating furnace, heated to 45°C under a protective atmosphere of nitrogen, maintained at this temperature for 78 minutes, and then cooled to room temperature to obtain a mixed solid; then a ferric chloride solution with a concentration of 251 mg / L is prepared, 0.9 g of the mixed solid is added to each liter of the ferric chloride solution, and the mixture is stirred at a stirring speed of 45 rpm for 25 minutes to obtain the composite oxidizing coagulant.

[0064] Then, the primary treatment liquid is transported to an ozone catalytic oxidation tower 22 equipped with a modified water slag catalyst via a secondary water inlet pump 21. The height-to-diameter ratio of the ozone catalytic oxidation tower 22 is 4:1, and the volume ratio of the modified water slag catalyst to the ozone catalytic oxidation tower 22 is 80%. After the primary treatment liquid remains in the ozone catalytic oxidation tower 22 for 39 minutes, a secondary treatment liquid is obtained, and the secondary treatment liquid is discharged via a drainage pump 23. Specifically, the TDS of the secondary treatment liquid is 24521 mg / L, the suspended solids concentration is 6 mg / L, the benzofluoranthene concentration is 16.8 μg / L, and the perfluoroalkyl compound concentration is 324 ng / L. It can be seen that the secondary treatment liquid meets the emission standards or reuse requirements and can be directly discharged or transported to a near-zero emission wastewater system.

[0065] More specifically, in this example, the modified water slag catalyst was prepared by the following steps: selecting water slag with a particle size of 2.4 mm; soaking the water slag in a hydrochloric acid solution with a mass fraction of 2.8% for 75 minutes, taking it out and placing it in a 115°C forced air drying furnace for 112 minutes, and then cooling it to room temperature; then preparing a mixed solution of water slag, ferric chloride, copper chloride and pure water in a volume ratio of 6:2:3:65 and placing it in an autoclave, adding 1 mL of dioxane and 0.3 g of chloromethylated polystyrene to each liter of the mixed solution; finally, sealing the autoclave, filling it with nitrogen, and heating it to 182°C. After maintaining it at this temperature for 142 minutes, the mixed solution was cooled to room temperature and filtered to obtain the modified water slag catalyst.

[0066] Example 2: The water quality characteristics of the coking reverse osmosis concentrated water are: TDS 31485 mg / L, suspended solids concentration 124 mg / L, benzofluoranthene concentration 48.7 μg / L, and perfluoroalkyl compound concentration 1457 ng / L. The treatment steps for the coking reverse osmosis concentrated water are as follows:

[0067] First, the coking reverse osmosis concentrate was pumped to the dosing and mixing zone of the coagulation and sedimentation tank 12 via a primary water inlet pump 11. Simultaneously, a dosing device 13 was controlled to add a composite oxidizing coagulant to the dosing and mixing zone at a rate of 314 mL per ton of coking reverse osmosis concentrate. The coking reverse osmosis concentrate and the composite oxidizing coagulant were thoroughly mixed for 6 minutes. After the coking reverse osmosis concentrate remained in the sedimentation zone for 19 minutes, a primary treated liquid was obtained. Specifically, the primary treated liquid had a TDS of 31,041 mg / L, a suspended solids concentration of 15 mg / L, a benzofluoranthene concentration of 35.9 μg / L, and a perfluoroalkyl compound concentration of 924 ng / L.

[0068] Specifically, in this example, the composite oxidizing coagulant is prepared by the following steps: selecting a particle size of 150 mesh and a specific surface area of ​​20.1m 2 / g of diatomaceous earth; diatomaceous earth, potassium ferrate and potassium permanganate are mixed in a mass ratio of 12:4:3, conveyed to a mixer and ground for 35 minutes to obtain a mixed powder; the mixed powder is then placed in a heating furnace, heated to 46°C under a protective atmosphere of nitrogen, maintained at this temperature for 83 minutes, and then cooled to room temperature to obtain a mixed solid; then a ferric chloride solution with a concentration of 279 mg / L is prepared, 1.2 g of the mixed solid is added to each liter of the ferric chloride solution, and the mixture is stirred at a stirring speed of 50 rpm for 30 minutes to obtain the composite oxidizing coagulant.

[0069] The primary treatment liquid is then transported to an ozone catalytic oxidation tower 22 equipped with a modified water slag catalyst via a secondary water inlet pump 21. The height-to-diameter ratio of the ozone catalytic oxidation tower 22 is 4:1, and the volume ratio of the modified water slag catalyst to the ozone catalytic oxidation tower 22 is 82%. After the primary treatment liquid remains in the ozone catalytic oxidation tower 22 for 42 minutes, a secondary treatment liquid is obtained, which is then discharged via a drainage pump 23. Specifically, the TDS of the secondary treatment liquid is 30112 mg / L, the suspended solids concentration is 9 mg / L, the benzofluoranthene concentration is 19.3 μg / L, and the perfluoroalkyl compound concentration is 415 ng / L. This shows that the secondary treatment liquid meets the emission standards or reuse requirements and can be directly discharged or transported to a near-zero discharge system for wastewater.

[0070] More specifically, in this example, the modified water slag catalyst was prepared by the following steps: selecting water slag with a particle size of 2.5 mm; soaking the water slag in a hydrochloric acid solution with a mass fraction of 3.1% for 80 minutes, taking it out and placing it in a 115°C forced air drying furnace for 125 minutes, and then cooling it to room temperature; then preparing a mixed solution of water slag, ferric chloride, copper chloride and pure water in a volume ratio of 7:2:3:70 and placing it in an autoclave, adding 2 mL of dioxane and 0.4 g of chloromethylated polystyrene to each liter of the mixed solution; finally, sealing the autoclave, filling it with nitrogen, and heating it to 190°C. After maintaining it at this temperature for 150 minutes, the mixed solution was cooled to room temperature and filtered to obtain the modified water slag catalyst.

[0071] Example 2

[0072] This embodiment provides a system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water. Figure 3 , Figure 3 The structural block diagram of the system for removing benzofluoranthene and perfluoroalkyl compounds from the coking reverse osmosis concentrated water provided in this embodiment. Figure 3 It can be seen that the system includes a coagulation and sedimentation module 1 and an ozone catalytic oxidation module 2 arranged in sequence; the coagulation and sedimentation module 1 is configured to use a compound oxidizing coagulant to perform coagulation and sedimentation treatment on the coking reverse osmosis concentrated water to obtain a primary treatment liquid; the ozone catalytic oxidation module 2 is configured to transport the primary treatment liquid to an ozone catalytic oxidation tower 22 equipped with a modified water slag catalyst for ozone catalytic oxidation treatment to obtain a secondary treatment liquid.

[0073] Since the system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided in this embodiment belongs to the same inventive concept as the method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water described in any of the above-mentioned embodiments, the system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided in this embodiment has at least all the advantages of the method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided in the above-mentioned embodiments. For the advantages of the system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided in this embodiment, please refer to the relevant description of the beneficial effects of the method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided in the above-mentioned embodiments, which will not be repeated here.

[0074] In summary, the method and system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present application have the following advantages: the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present application comprises: using a compound oxidizing coagulant to coagulate and precipitate the coking reverse osmosis concentrated water to obtain a first treatment liquid; and conveying the first treatment liquid to an ozone catalytic oxidation tower provided with a modified water slag catalyst to perform ozone catalytic oxidation treatment, thereby obtaining a second treatment liquid. Thus, the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present application can coagulate and precipitate the coking reverse osmosis concentrated water by using a compound oxidizing coagulant, the oxidizing agent (for example, including but not limited to potassium ferrate and potassium permanganate) in the compound oxidizing coagulant can produce a strong oxidizing substance to decompose the benzofluoranthene and perfluoroalkyl compounds and other refractory organic matters in the coking reverse osmosis concentrated water, the coagulant (for example, including but not limited to ferric chloride solution) in the compound oxidizing coagulant can improve the settling speed and efficiency of suspended solids, and under the synergistic effect of oxidation and coagulation of the compound oxidizing coagulant, the removal effect of the benzofluoranthene and perfluoroalkyl compounds and other refractory organic matters in the coking reverse osmosis concentrated water can be improved. Then, the first treatment liquid is conveyed to the ozone catalytic oxidation tower provided with the modified water slag catalyst to perform ozone catalytic oxidation treatment, which can improve the ozone catalytic oxidation efficiency of the first treatment liquid, thereby further improving the removal effect of the benzofluoranthene and perfluoroalkyl compounds and other refractory organic matters in the coking reverse osmosis concentrated water. The method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present application can effectively remove the benzofluoranthene and perfluoroalkyl compounds and other refractory organic matters in the coking reverse osmosis concentrated water, thereby reducing environmental pollution.

[0075] Since the system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present application belongs to the same inventive concept as the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water described in any one of the above, the system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present application at least has all the advantages of the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present application. For the advantages of the system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present application, please refer to the relevant description of the advantages of the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present application, which will not be described here in detail.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water, characterized in that: The method comprises: Using a composite oxidizing coagulant to perform coagulation and sedimentation treatment on the coking reverse osmosis concentrated water to obtain a primary treated liquid; The primary treatment liquid is transported to an ozone catalytic oxidation tower equipped with a modified water slag catalyst for ozone catalytic oxidation treatment to obtain a secondary treatment liquid; wherein the modified water slag catalyst is prepared by the following steps: SB1: Select water slag with a particle size of 1.5 mm to 3.2 mm; SB2: Soak the slag in a hydrochloric acid solution with a mass fraction of 2.3% to 4.6% for 67 to 89 minutes, remove it and place it in a drying device for 95 to 135 minutes, and then cool it to room temperature; SB3: Prepare a mixed solution of the water slag, ferric chloride, copper chloride, and pure water in a volume ratio of (6-7):2:3:(60-80) and place the solution in a reaction vessel. Add 1 mL-3 mL of dioxane and 0.2 g-0.5 g of chloromethylated polystyrene per liter of the mixed solution. SB4: The reaction vessel is heated to 175° C. to 197° C., and maintained at this temperature for 125 minutes to 176 minutes, and then the mixed solution is cooled to room temperature and filtered to obtain the modified water slag catalyst.

2. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, wherein: The water quality of the coking reverse osmosis concentrated water before treatment is as follows: the concentration of benzofluoranthene is 34.1 μg / L~56.5 μg / L, and the concentration of perfluoroalkyl compounds is 821 ng / L~1785 ng / L.

3. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, wherein: The method of using a composite oxidizing coagulant to perform coagulation and sedimentation treatment on the coking reverse osmosis concentrated water to obtain a primary treated liquid comprises: transporting the coking reverse osmosis concentrated water to a coagulation sedimentation tank; The composite oxidizing coagulant is added to the coagulation sedimentation tank, so that the coking reverse osmosis concentrated water and the composite oxidizing coagulant undergo a coagulation and precipitation reaction in the coagulation sedimentation tank to obtain the primary treated liquid.

4. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, wherein: 234 mL to 356 mL of the composite oxidizing coagulant is added to each ton of the coking reverse osmosis concentrated water.

5. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, characterized in that: The composite oxidizing coagulant is prepared by the following steps: SA1: Select particle size of 100-300 mesh and specific surface area of ​​14.2m 2 / g~26.1m 2 / g of diatomaceous earth; SA2: The diatomaceous earth, potassium ferrate, and potassium permanganate were mixed in a mass ratio of (9-15):4:3, and the mixture was transferred to a mixer and ground for 25-37 minutes to obtain a mixed powder; SA3: placing the mixed powder in a heating device and heating it to 42° C. to 47° C., maintaining the temperature for 72 minutes to 89 minutes, and then cooling it to room temperature to obtain a mixed solid; SA4: Prepare a ferric chloride solution with a concentration of 234 mg / L to 303 mg / L, add 0.7 g to 1.5 g of the mixed solid per liter of the ferric chloride solution, and stir at a stirring speed of 40 rpm to 55 rpm for 21 minutes to 34 minutes to obtain the composite oxidizing coagulant.

6. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, wherein: The volume ratio of the modified water slag catalyst to the ozone catalytic oxidation tower is 75% to 85%; the residence time of the primary treatment liquid in the ozone catalytic oxidation tower is 37 minutes to 46 minutes.

7. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, characterized in that: The ratio of the height to the diameter of the ozone catalytic oxidation tower is 4:

1.

8. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, wherein: The water quality of the secondary treatment liquid is as follows: the concentration of benzofluoranthene is 14.2 μg / L to 21.1 μg / L, and the concentration of perfluoroalkyl compound is 234 ng / L to 511 ng / L.

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