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

Abstract

The invention provides a method and system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water, and the method comprises the following steps: carrying out coagulating sedimentation treatment on the coking reverse osmosis concentrated water by using a compound oxidation coagulant to obtain a primary treatment liquid; and conveying the primary treatment liquid to a catalytic ozonation tower with a modified water slag catalyst, and carrying out catalytic ozonation treatment to obtain a secondary treatment liquid. According to the method and the system for removing the benzofluoranthene and the perfluoroalkyl compounds in the coking reverse osmosis concentrated water, provided by the invention, the coking reverse osmosis concentrated water is subjected to coagulating sedimentation treatment, so that refractory organic matters such as the benzofluoranthene and the perfluoroalkyl compounds in the coking reverse osmosis concentrated water can be preliminarily removed; therefore, the effect of subsequent catalytic ozonation treatment can be improved. The coking reverse osmosis concentrated water is subjected to catalytic ozonation treatment, so that refractory organic matters such as benzofluoranthene and perfluoroalkyl compounds in the coking reverse osmosis concentrated water can be further removed, and environmental pollution can be reduced.

Description

Technical Field

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

[0002] Coking wastewater is a high-concentration and complex industrial wastewater, containing a variety of inorganic and organic pollutants, such as chemical oxygen demand (COD), ammonia nitrogen, thiocyanate, phenols, aniline, benzofluoranthene and other harmful substances. Among them, benzofluoranthene is a typical difficult-to-biodegrade organic matter, and perfluoroalkyl compounds, due to their high stability and bioaccumulation, will pose a serious threat to the environment and human health.

[0003] In the treatment of coking wastewater, reverse osmosis technology is widely used due to its excellent desalination performance and low energy consumption. However, the application of reverse osmosis technology produces a large amount of concentrated water, which not only contains high concentrations of salt, but also is enriched with a variety of difficult-to-degrade organic matter including benzofluoranthene and perfluoroalkyl compounds. These organic matter are extremely toxic and stable, and are difficult to effectively remove through traditional biological treatment methods, which will pose a serious threat to the environment and ecosystem. Summary of the invention

[0004] The object of the present invention is to provide a method and system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water, so as to solve one or more problems existing in the prior art, namely, that benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water are difficult to be effectively removed by traditional biological treatment methods and pose a serious threat to the environment and ecosystem.

[0005] To achieve the above object, the present invention is implemented by the following technical scheme: a method for removing benzofluoranthene and perfluoroalkyl compounds in 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: conveying 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: Select 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: after mixing the diatomaceous earth, potassium ferrate and potassium permanganate in a mass ratio of (9-15):4:3, conveying them to a mixer and grinding them 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, and keeping it at this temperature for 72 minutes to 89 minutes, cooling it to room temperature to obtain a mixed solid; SA4: preparing a ferric chloride solution with a concentration of 234mg / L to 303mg / L, adding 0.7g to 1.5g of the mixed solid to each liter of the ferric chloride solution, 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 container, adding 1 mL to 3 mL of dioxane and 0.2 g to 0.5 g of chloromethylated polystyrene per liter of the mixed solution; SB4: heating the reaction container 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 purpose, the present invention also provides a system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrate, 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 concentrate 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 in coking reverse osmosis concentrated water provided by the present invention have the following beneficial effects:

[0018] The method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present invention comprises: using a composite oxidizing coagulant to perform coagulation and precipitation treatment on the coking reverse osmosis concentrated water to obtain a primary treatment liquid; 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 coking reverse osmosis concentrated water by using a composite oxidation coagulant, the oxidant in the composite oxidation 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 oxidation 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 oxidation and coagulation of the composite oxidation coagulant, thereby improving the removal effect of the benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic matter in the coking reverse osmosis concentrated water. 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 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 in coking reverse osmosis concentrated water provided by the present invention can effectively remove benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic substances in coking reverse osmosis concentrated water, thereby reducing environmental pollution.

[0019] Since the system for removing benzofluoranthene and perfluoroalkyl compounds in 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 in coking reverse osmosis concentrated water described in any of the above items, the system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present invention 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 invention. For the advantages of the system for removing benzofluoranthene and perfluoroalkyl compounds in 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 in 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 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-primary 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 following is a further detailed description of the method and system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water proposed by the present invention in combination with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the accompanying drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Any modification of the structure, change in the proportional relationship or adjustment of the size, in the case of the same or similar effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention. The specific design features of the present invention disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific environment to be applied and used. Furthermore, in the embodiments described below, the same reference numerals may be used in common among different drawings to indicate the same parts or parts having the same functions, and their repeated descriptions may be omitted.

[0026] It should be understood that, unless otherwise stated or obvious from the context, as used herein, the term "about" is understood to be within the normal tolerance range in the art, such as 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 value. Unless otherwise clear from the context, all numerical values ​​provided herein are modified by the term "about".

[0027] Embodiment 1

[0028] This embodiment provides a method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrate. Figure 1 and Figure 2 , Figure 1 A schematic diagram of the overall steps of the method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water provided in this embodiment; Figure 2 The specific process diagram of the method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrate provided in this embodiment. Figure 1 and Figure 2 It can be seen that the method comprises:

[0029] S100: using a composite oxidizing coagulant to perform coagulation and sedimentation treatment on the coking reverse osmosis concentrated water to obtain a primary treated 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 treat the coking reverse osmosis concentrated water with coagulation and precipitation 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 strong oxidizing substances to decompose the benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organics 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, and under the synergistic effect of oxidation and coagulation of the composite oxidizing coagulant, the removal effect of the benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organics in the coking reverse osmosis concentrated water can be improved. Then, by transporting the primary treatment liquid to the ozone catalytic oxidation tower 22 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 the benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organics 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 invention can effectively remove benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic substances in coking reverse osmosis concentrated water, thereby reducing environmental pollution.

[0032] Exemplarily, 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 23345mg / L~34678mg / L, suspended matter concentration is about 89mg / L~139mg / L, benzofluoranthene concentration is about 34.1μg / L~56.5μg / L, and perfluoroalkyl compound concentration is about 821ng / L~1785ng / L.

[0033] Preferably, the step S100 uses a compound oxidizing coagulant to perform coagulation and sedimentation treatment on the coking reverse osmosis concentrate to obtain a primary treatment liquid, including: conveying the coking reverse osmosis concentrate to a coagulation and sedimentation tank 12; adding the compound oxidizing coagulant to the coagulation and sedimentation tank 12, so that the coking reverse osmosis concentrate and the compound oxidizing coagulant undergo a coagulation and sedimentation reaction in the coagulation and sedimentation tank 12 to obtain the primary treatment liquid. Therefore, by adding a compound oxidizing coagulant into the coagulation sedimentation tank 12, the oxidant in the compound oxidizing coagulant (exemplarily including but not limited to potassium ferrate and potassium permanganate) can produce strong oxidizing substances to decompose difficult-to-degrade organic matter such as benzofluoranthene and perfluoroalkyl compounds in the coking reverse osmosis concentrate, and the coagulant in the compound oxidizing coagulant (exemplarily including but not limited to ferric chloride solution) can increase the sedimentation rate and efficiency of suspended matter. Under the synergistic effect of oxidation and coagulation of the compound oxidizing coagulant, the removal effect of difficult-to-degrade organic matter such as benzofluoranthene and perfluoroalkyl compounds in the coking reverse osmosis concentrate can be improved.

[0034] For example, in some exemplary embodiments, the front part of the coagulation sedimentation tank 12 is a dosing mixing zone (not shown in the figure), and the dosing mixing zone is connected to a dosing device 13, and the dosing device 13 adds a compound oxidizing coagulant to the dosing mixing zone at a dosing ratio of about 234mL to 356mL of the compound oxidizing coagulant per ton of the coking reverse osmosis concentrated water. A stirring device (not shown in the figure) is provided in the dosing 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 sedimentation tank 12 is a sedimentation zone (not shown in the figure), and the residence time of the coking reverse osmosis concentrated water in the sedimentation zone is 17 minutes to 20 minutes.

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

[0036] SA1: Select 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;

[0037] SA2: After mixing the diatomaceous earth, potassium ferrate and potassium permanganate in a mass ratio of (9-15):4:3, the mixture is conveyed to a mixer and ground for 25-37 minutes to obtain a mixed powder;

[0038] 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;

[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, the composite oxidation coagulant is prepared according to the above steps, so that the oxidation effect and coagulation effect of the composite oxidation coagulant are better, which lays a good foundation for improving the removal effect of refractory organic matter such as benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water. It should be noted that the parameters given in the preparation process of the above composite oxidation coagulant are only exemplary, and these parameters should be reasonably set according to the water quality characteristics of the coking reverse osmosis concentrated water.

[0041] It should be noted that, as those skilled in the art can understand, the present invention does not impose too many restrictions on the type of the heating device. For example, in some exemplary embodiments, the heating device can be a heating furnace, and the heating furnace uses nitrogen as the protective atmosphere.

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

[0046] SB3: The water slag, ferric chloride, copper chloride and pure water are prepared into a mixed solution in a volume ratio of (6-7):2:3:(60-80) and placed in a reaction container, and 1 mL-3 mL of dioxane and 0.2 g-0.5 g of chloromethylated polystyrene are added to each liter of the mixed solution;

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

[0048] Thus, the modified water slag catalyst is prepared according to the above steps, so that the modified water slag catalyst has better catalytic performance, which lays a good foundation for improving the removal effect of refractory organic matter such as benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water. It should be noted that the parameters given in the preparation process of the above modified water slag catalyst are only exemplary, and these parameters should be reasonably set according to the water quality characteristics of the coking reverse osmosis concentrated water.

[0049] It should be noted that, as can be understood by those skilled in the art, the present invention does not impose too many restrictions on the types of the drying device and the reaction container. For example, in some exemplary embodiments, the drying device can be a forced air drying furnace, the set temperature of which is 115°C; the reaction container can be an autoclave, and before the autoclave is heated, the autoclave is first sealed and then filled with nitrogen to exclude air and create 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%; the residence time of the primary treatment liquid in the ozone catalytic oxidation tower 22 is 37 minutes to 46 minutes. Thus, the treatment effect and operation efficiency of the ozone catalytic oxidation tower 22 can be significantly improved, so that the refractory organic matter such as benzofluoranthene and perfluoroalkyl compounds in the coking reverse osmosis concentrated water can be better removed. In addition, the operation energy consumption and operation cost of the ozone catalytic oxidation tower 22 can be reduced.

[0051] Preferably, the ratio of the height to the diameter of the ozone catalytic oxidation tower 22 is 4: 1. Thus, the treatment effect and operation efficiency of the ozone catalytic oxidation tower 22 can be further improved, and the operation energy consumption and operation cost of the ozone catalytic oxidation tower 22 can be reduced.

[0052] For example, in some exemplary embodiments, the water quality of the obtained secondary treatment liquid is: 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.

[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 is 23345mg / L~34678mg / L, suspended solids concentration is 89mg / L~139mg / L, benzofluoranthene concentration is 34.1μg / L~56.5μg / L, and perfluoroalkyl compound concentration is 821ng / L~1785ng / L. The treatment steps for the coking reverse osmosis concentrated water are as follows:

[0055] First, the coking reverse osmosis concentrated water is transported to the dosing mixing area of ​​the coagulation sedimentation tank 12 by the primary water inlet pump 11. At the same time, the dosing device 13 is controlled to add the composite oxidizing coagulant to the dosing mixing area at a dosing ratio of 234mL to 356mL of the composite oxidizing coagulant per ton of coking reverse osmosis concentrated water, so that the coking reverse osmosis concentrated water and the composite oxidizing coagulant are fully mixed for 3.5 minutes to 6 minutes. After the coking reverse osmosis concentrated water stays in the sedimentation area for 17 minutes to 20 minutes, the primary treatment liquid is obtained. Specifically, the TDS of the primary treatment liquid is 23345mg / L to 34678mg / L, the suspended matter concentration is 7mg / L to 17mg / L, the benzofluoranthene concentration is 24.3μg / L to 39.1μg / L, and the perfluoroalkyl compound concentration is 567ng / L to 1103ng / 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 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 to 42°C to 47°C under a nitrogen protective atmosphere, and maintaining at this temperature for 72 minutes to 89 minutes, cooling to room temperature to obtain a mixed solid; then preparing a ferric chloride solution with a concentration of 234mg / L to 303mg / L, adding 0.7g to 1.5g of the mixed solid to each liter of the ferric chloride solution, 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 provided with a modified water slag catalyst by the 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 stays in the ozone catalytic oxidation tower 22 for 37 minutes to 46 minutes, the secondary treatment liquid is obtained, and the secondary treatment liquid is discharged by the drainage pump 23. Specifically, the TDS of the secondary treatment liquid is 23345mg / L to 34678mg / L, the suspended matter concentration is 5mg / L to 11mg / L, the benzofluoranthene concentration is 14.2μg / L to 21.1μg / L, and the perfluoroalkyl compound concentration is 234ng / L to 511ng / L. It can be seen that the secondary treatment liquid meets the discharge standard or reuse requirements and can be directly discharged or transported to the near-zero discharge system of 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 115°C forced air drying furnace for drying for 95 minutes to 135 minutes, and then cooling it to room temperature; then preparing a mixed solution of water slag, ferric chloride, copper chloride and pure water according to a volume ratio of (6 to 7): 2: 3: (60 to 80) and placing it in an autoclave, adding 1 mL to 3 mL of dioxane and 0.2 g to 0.5 g of chloromethylated polystyrene per liter of the mixed solution; finally, sealing the autoclave and filling it with nitrogen and heating it to 175°C to 197°C, keeping 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.

[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] In order to facilitate further understanding of the present invention, the present invention is 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 is 25649 mg / L, suspended solids concentration is 98 mg / L, benzofluoranthene concentration is 37.8 μg / L, and perfluoroalkyl compound concentration is 978 ng / L. The treatment steps for the coking reverse osmosis concentrated water are as follows:

[0062] First, the coking reverse osmosis concentrated water is transported to the dosing mixing area of ​​the coagulation sedimentation tank 12 by the primary water inlet pump 11. At the same time, the dosing device 13 is controlled to add the composite oxidizing coagulant to the dosing mixing area at a dosing ratio of 264 mL of the composite oxidizing coagulant per ton of coking reverse osmosis concentrated water, so that the coking reverse osmosis concentrated water and the composite oxidizing coagulant are fully mixed for 4.3 minutes. After the coking reverse osmosis concentrated water stays in the sedimentation area for 18 minutes, the primary treatment liquid is obtained. Specifically, the TDS of the primary treatment liquid is 25517 mg / L, the suspended matter concentration is 12 mg / L, the benzofluoranthene concentration is 28.1 μg / L, and the perfluoroalkyl compound concentration is 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; after mixing diatomaceous earth, potassium ferrate and potassium permanganate in a mass ratio of 10:4:3, conveying to a mixer and grinding for 28 minutes to obtain a mixed powder; then putting the mixed powder into a heating furnace, heating to 45°C under a nitrogen protective atmosphere, and keeping at this temperature for 78 minutes, cooling to room temperature to obtain a mixed solid; then preparing a ferric chloride solution with a concentration of 251 mg / L, adding 0.9 g of the mixed solid to each liter of the ferric chloride solution, stirring 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 provided with a modified water slag catalyst by 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 stays in the ozone catalytic oxidation tower 22 for 39 minutes, a secondary treatment liquid is obtained, and the secondary treatment liquid is discharged by a drainage pump 23. Specifically, the TDS of the secondary treatment liquid is 24521 mg / L, the suspended matter 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 discharge standards or reuse requirements and can be directly discharged or transported to a near-zero discharge system for wastewater.

[0065] More specifically, in this example, the modified water slag catalyst is 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 drying 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, keeping it at this temperature for 142 minutes, cooling the mixed solution to room temperature and filtering it to obtain the modified water slag catalyst.

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

[0067] First, the coking reverse osmosis concentrated water is transported to the dosing mixing area of ​​the coagulation sedimentation tank 12 by the primary water inlet pump 11. At the same time, the dosing device 13 is controlled to add the composite oxidizing coagulant to the dosing mixing area at a dosing ratio of 314 mL of the composite oxidizing coagulant per ton of coking reverse osmosis concentrated water, so that the coking reverse osmosis concentrated water and the composite oxidizing coagulant are fully mixed for 6 minutes. After the coking reverse osmosis concentrated water stays in the sedimentation area for 19 minutes, the primary treatment liquid is obtained. Specifically, the TDS of the primary treatment liquid is 31041 mg / L, the suspended matter concentration is 15 mg / L, the benzofluoranthene concentration is 35.9 μg / L, and the perfluoroalkyl compound concentration is 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 ​​20.1 m 2 / g of diatomaceous earth; after mixing diatomaceous earth, potassium ferrate and potassium permanganate in a mass ratio of 12:4:3, conveying to a mixer and grinding for 35 minutes to obtain a mixed powder; then putting the mixed powder into a heating furnace, heating to 46°C under a nitrogen protective atmosphere, and keeping at this temperature for 83 minutes, cooling to room temperature to obtain a mixed solid; then preparing a ferric chloride solution with a concentration of 279 mg / L, adding 1.2 g of the mixed solid to each liter of the ferric chloride solution, stirring at a stirring speed of 50 rpm for 30 minutes, to obtain the composite oxidizing coagulant.

[0069] Then, the primary treatment liquid is transported to an ozone catalytic oxidation tower 22 provided with a modified water slag catalyst by 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 stays in the ozone catalytic oxidation tower 22 for 42 minutes, a secondary treatment liquid is obtained, and the secondary treatment liquid is discharged by a drainage pump 23. Specifically, the TDS of the secondary treatment liquid is 30112 mg / L, the suspended matter concentration is 9 mg / L, the benzofluoranthene concentration is 19.3 μg / L, and the perfluoroalkyl compound concentration is 415 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.

[0070] More specifically, in this example, the modified water slag catalyst is 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 drying 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, keeping it at this temperature for 150 minutes, cooling the mixed solution to room temperature and filtering it to obtain the modified water slag catalyst.

[0071] Embodiment 2

[0072] This embodiment provides a system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrate. Figure 3 , Figure 3 The structural block diagram of the system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrate 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 which are 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 provided 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 the present 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 the present 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 the present 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 invention have the following advantages: the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present invention comprises: using a composite oxidizing coagulant to perform coagulation and precipitation treatment on the coking reverse osmosis concentrated water to obtain a primary treatment liquid; transporting 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. 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 coking reverse osmosis concentrated water by using a composite oxidation coagulant, the oxidant in the composite oxidation 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 oxidation 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 oxidation and coagulation of the composite oxidation coagulant, thereby improving the removal effect of the benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic matter in the coking reverse osmosis concentrated water. 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 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 in coking reverse osmosis concentrated water provided by the present invention can effectively remove benzofluoranthene and perfluoroalkyl compounds and other difficult-to-degrade organic substances in 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 invention belongs to the same inventive concept as the method for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water described in any of the above items, the system for removing benzofluoranthene and perfluoroalkyl compounds in coking reverse osmosis concentrated water provided by the present invention 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 invention. For the advantages of the system for removing benzofluoranthene and perfluoroalkyl compounds in 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 in coking reverse osmosis concentrated water provided by the present invention, which will not be repeated here.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. 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 solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution 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.

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

3. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, characterized in that: 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: The coking reverse osmosis concentrated water is transported to a coagulation sedimentation tank; The composite oxidizing coagulant is added into the coagulation sedimentation tank, so that the coking reverse osmosis concentrated water and the composite oxidizing coagulant undergo a coagulation and sedimentation reaction in the coagulation sedimentation tank to obtain the primary treatment liquid.

4. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, characterized in that: 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 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: After mixing the diatomaceous earth, potassium ferrate and potassium permanganate in a mass ratio of (9-15):4:3, the mixture is conveyed 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, characterized in that: 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: 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: The water slag, ferric chloride, copper chloride and pure water are prepared into a mixed solution in a volume ratio of (6-7):2:3:(60-80) and placed in a reaction container, and 1 mL-3 mL of dioxane and 0.2 g-0.5 g of chloromethylated polystyrene are added to each liter of the mixed solution; SB4: The reaction container is heated to 175° C. to 197° C., and after maintaining the temperature for 125 minutes to 176 minutes, the mixed solution is cooled to room temperature and filtered to obtain the modified water slag catalyst.

7. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, characterized in that: 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.

8. 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.

9. The method for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water according to claim 1, characterized in that: 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.

10. A system for removing benzofluoranthene and perfluoroalkyl compounds from coking reverse osmosis concentrated water, characterized in that: The system comprises a coagulation and sedimentation module and an ozone catalytic oxidation module which are arranged in sequence; The coagulation and sedimentation module is configured to use a composite oxidizing coagulant to perform coagulation and sedimentation treatment on the coking reverse osmosis concentrated water to obtain a primary treated liquid; The ozone catalytic oxidation module is configured to transport the primary treatment liquid to an ozone catalytic oxidation tower provided with a modified water-slag catalyst for ozone catalytic oxidation treatment to obtain a secondary treatment liquid.

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