Method and system for treating nanofiltration concentrated water

Abstract

The invention provides a nanofiltration concentrated water treatment method and system.The treatment method comprises the steps that nanofiltration concentrated water is conveyed to a catalytic ozonation tower provided with a modified biochar catalyst to be subjected to catalytic ozonation treatment, and primary treatment liquid is obtained; and carrying out biochemical treatment on the primary treatment liquid to obtain a secondary treatment liquid. According to the nanofiltration concentrated water treatment method and system provided by the invention, the nanofiltration concentrated water is subjected to catalytic ozonation treatment, so that pollutants such as soluble organic matters, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrated water can be effectively decomposed, the organic load in the nanofiltration concentrated water is reduced, and the biodegradability of the nanofiltration concentrated water is improved; and a good foundation is laid for relieving the burden of subsequent biochemical treatment and improving the treatment efficiency of the nanofiltration concentrated water. The nanofiltration concentrated water is subjected to biochemical treatment, and pollutants in the nanofiltration concentrated water can be further removed, so that the environmental pollution can be reduced, and the recycling of resources is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a method and system for treating nanofiltration concentrated water. Background Art

[0002] my country's steel industry has maintained a high growth trend in recent years, with annual output growth ranging from 15% to 22%. However, the steel industry is also an industry with high energy consumption, high resource consumption and high pollution. Its water consumption is huge, accounting for about 14% of the country's total industrial water consumption.

[0003] A large amount of wastewater is generated during the steel production process, among which nanofiltration concentrate is the high-concentration wastewater remaining after nanofiltration treatment. This type of wastewater contains high concentrations of pollutants such as salt and organic matter. If it is discharged directly, it will not only cause serious pollution to the environment, but also waste precious water resources. Therefore, how to efficiently treat the nanofiltration concentrate generated during the steel production process and realize the reuse of resources has become one of the technical problems that technicians in this field need to solve urgently. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for treating nanofiltration concentrate to solve one or more problems existing in the prior art, such as direct discharge of nanofiltration concentrate generated in the steel production process causing serious environmental pollution and wasting water resources.

[0005] To achieve the above object, the present invention is implemented through the following technical scheme: a method for treating nanofiltration concentrate, comprising: transporting the nanofiltration concentrate to an ozone catalytic oxidation tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a secondary treatment liquid.

[0006] Optionally, the modified biochar catalyst is prepared by the following steps: SA1: selecting hemp stalks as biochar raw materials and washing them 2 to 3 times, preparing a calcium hydroxide solution with a mass fraction of 3% to 5%, soaking the washed hemp stalks in the calcium hydroxide solution for 75 to 95 minutes, taking them out and drying them, placing the hemp stalks in a drying device and drying them for 90 to 105 minutes, and then cooling them to room temperature; SA2: placing the hemp stalks in a heating device and heating them at a temperature of 3°C / min to 5°C / min. The method comprises the following steps: heating the mixture to 515°C to 603°C at a speed of 100 to 200°C, maintaining the mixture at a temperature of 515°C to 603°C for 45 to 67 minutes, cooling the mixture to room temperature, obtaining hemp stalk biochar, grinding the cooled hemp stalk biochar into fine powder, and screening out the hemp stalk biochar fine powder of 100 to 200 meshes; SA3: preparing a manganese nitrate solution with a concentration of 13% to 17% and a copper chloride solution with a concentration of 5% to 9% calculated on the basis of metal elements, and mixing the manganese nitrate solution with the copper chloride solution in a volume ratio of 1: (3 to 4). After mixing, a first mixed solution is obtained, and 2 mL to 5 mL of triethyl phosphate with a concentration of 16 mol / L is added to each liter of the first mixed solution, and the mixture is stirred at a stirring speed of 55 rpm to 65 rpm for 210 minutes to 275 minutes to obtain a second mixed solution; SA4: the hemp stalk biochar fine powder is mixed with the second mixed solution in a volume ratio of 1: (5 to 7), and the hemp stalk biochar fine powder is soaked in the second mixed solution for 530 minutes to 710 minutes. Take it out and dry it; SA5: put the dried hemp stalk biochar fine powder into the heating device, heat it to 235°C~241°C at a heating rate of 2°C / min~5°C / min, keep it at 235°C~241°C for 45 minutes to 58 minutes, and continue to heat it to 332°C~347°C at a heating rate of 2°C / min~5°C / min, keep it at 332°C~347°C for 118 minutes to 137 minutes, and then cool it to room temperature to obtain the modified biochar catalyst.

[0007] Optionally, the volume ratio of the modified biochar catalyst to the ozone catalytic oxidation tower is 82% to 87%.

[0008] Optionally, the residence time of the nanofiltration concentrated water in the ozone catalytic oxidation tower ranges from 51 minutes to 62 minutes.

[0009] Optionally, the ozone source in the ozone catalytic oxidation tower includes an oxygen source, and the ozone concentration in the ozone catalytic oxidation tower includes 65g / m 3 ~80g / m 3 .

[0010] Optionally, the nanofiltration concentrate includes steel nanofiltration concentrate, and the water quality of the steel nanofiltration concentrate is: sulfate ion concentration of 4530mg / L~6270mg / L, dissolved organic matter concentration of 234mg / L~343mg / L, ammonia nitrogen concentration of 12mg / L~19mg / L, and perfluoroalkyl compound concentration of 108.1ng / L~207.9ng / L.

[0011] Optionally, the biochemical treatment of the primary treatment liquid to obtain the secondary treatment liquid includes: conveying the primary treatment liquid to an aerobic aeration reactor for biochemical treatment to obtain the secondary treatment liquid; wherein a modified polyurethane filler is provided in the aerobic aeration reactor.

[0012] Optionally, the volume ratio of the modified polyurethane filler to the aerobic aeration reactor is 35% to 45%.

[0013] Optionally, the water quality of the secondary treatment liquid is: sulfate ion concentration is 4530mg / L~6270mg / L, dissolved organic matter concentration is 45mg / L~56mg / L, ammonia nitrogen concentration is 1mg / L~3mg / L, and perfluoroalkyl compound concentration is 29.1ng / L~56.1ng / L.

[0014] To achieve the above-mentioned purpose, the present invention also provides a system for treating nanofiltration concentrate, comprising an ozone catalytic oxidation module and a biochemical module arranged in sequence; the ozone catalytic oxidation module is configured to transport the nanofiltration concentrate to an ozone catalytic oxidation tower provided with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treatment liquid; the biochemical module is configured to perform biochemical treatment on the primary treatment liquid to obtain a secondary treatment liquid.

[0015] Compared with the prior art, the nanofiltration concentrated water treatment method and system provided by the present invention have the following beneficial effects:

[0016] The method for treating nanofiltration concentrated water provided by the present invention comprises: conveying the nanofiltration concentrated water to an ozone catalytic oxidation tower provided with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treatment liquid; and performing biochemical treatment on the primary treatment liquid to obtain a secondary treatment liquid. Thus, the method for treating nanofiltration concentrated water provided by the present invention is to convey the nanofiltration concentrated water to an ozone catalytic oxidation tower provided with a modified biochar catalyst for ozone catalytic oxidation treatment, and the modified biochar catalyst has good physical properties, and can effectively convert ozone into hydroxyl free radicals in the ozone catalytic oxidation reaction, thereby effectively degrading and adsorbing pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrated water, thereby significantly reducing the organic load in the nanofiltration concentrated water and improving the biodegradability of the nanofiltration concentrated water, laying a good foundation for reducing the burden of subsequent biochemical treatment and improving the treatment efficiency of the nanofiltration concentrated water. Then, by performing biochemical treatment on the nanofiltration concentrated water, pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrated water can be further removed. The method for treating nanofiltration concentrated water provided by the present invention can efficiently remove pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrated water, thereby reducing environmental pollution and facilitating the reuse of resources.

[0017] Furthermore, the biochemical treatment of the primary treatment liquid to obtain the secondary treatment liquid includes: transporting the primary treatment liquid to an aerobic aeration reactor for biochemical treatment to obtain the secondary treatment liquid; wherein the aerobic aeration reactor is provided with a modified polyurethane filler. Thus, the method for treating nanofiltration concentrated water provided by the present invention can further degrade biodegradable pollutants in the nanofiltration concentrated water by transporting the primary treatment liquid to an aerobic aeration reactor provided with a modified polyurethane filler for biochemical treatment.

[0018] Since the nanofiltration concentrate treatment system provided by the present invention belongs to the same inventive concept as the nanofiltration concentrate treatment method described in any of the above-mentioned items, the nanofiltration concentrate treatment system provided by the present invention at least has all the advantages of the nanofiltration concentrate treatment method provided by the present invention. For the advantages of the nanofiltration concentrate treatment system provided by the present invention, please refer to the relevant description of the beneficial effects of the nanofiltration concentrate treatment method provided by the present invention, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the overall steps of a method for treating nanofiltration concentrated water provided in Example 1 of the present invention;

[0020] Figure 2 A schematic diagram of a specific process of a method for treating nanofiltration concentrated water provided in Example 1 of the present invention;

[0021] Figure 3A structural block diagram of a nanofiltration concentrated water treatment system provided in Embodiment 2 of the present invention;

[0022] The following are the descriptions of the reference numerals:

[0023] 1- ozone catalytic oxidation module, 11- primary lifting pump, 12- ozone catalytic oxidation tower, 2- biochemical module, 21- secondary lifting pump, 22- aerobic aeration reactor, 23- drainage pump. DETAILED DESCRIPTION

[0024] The following is a further detailed description of the nanofiltration concentrated water treatment method and system 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 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 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. And, in the embodiments described below, sometimes the same figure mark is used in common between different drawings to represent the same part or part with the same function, and its repeated description is omitted.

[0025] 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".

[0026] Embodiment 1

[0027] This embodiment provides a method for treating nanofiltration concentrated water. Figure 1 and Figure 2 , Figure 1 A schematic diagram of the overall steps of the method for treating nanofiltration concentrated water provided in this embodiment; Figure 2 The specific process diagram of the method for treating nanofiltration concentrated water provided in this embodiment is as follows. Figure 1and Figure 2 It can be seen that the processing method includes:

[0028] S100: transporting the nanofiltration concentrated water to an ozone catalytic oxidation tower 12 equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treated liquid;

[0029] S200: performing biochemical treatment on the primary treatment liquid to obtain a secondary treatment liquid.

[0030] Thus, the method for treating nanofiltration concentrated water provided in this embodiment is to transport the nanofiltration concentrated water to an ozone catalytic oxidation tower 12 provided with a modified biochar catalyst for ozone catalytic oxidation treatment. The modified biochar catalyst has good physical properties and can effectively convert ozone into hydroxyl radicals in the ozone catalytic oxidation reaction, thereby effectively degrading and adsorbing pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrated water, thereby significantly reducing the organic load in the nanofiltration concentrated water and improving the biodegradability of the nanofiltration concentrated water, laying a good foundation for reducing the burden of subsequent biochemical treatment and improving the treatment efficiency of the nanofiltration concentrated water. Then, by biochemically treating the nanofiltration concentrated water, pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrated water can be further removed. The method for treating nanofiltration concentrated water provided by the present invention can efficiently remove pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrated water, thereby reducing environmental pollution and helping to achieve resource reuse.

[0031] Exemplarily, in some exemplary embodiments, the nanofiltration concentrate may be steel nanofiltration concentrate, and the water quality characteristics of the steel nanofiltration concentrate may be: sulfate ion concentration of 4530 mg / L to 6270 mg / L, dissolved organic matter concentration of 234 mg / L to 343 mg / L, ammonia nitrogen concentration of 12 mg / L to 19 mg / L, and perfluoroalkyl compound concentration of 108.1 ng / L to 207.9 ng / L.

[0032] It should be noted that the water quality characteristics of the obtained primary treatment liquid are: sulfate ion concentration is about 4530mg / L~6270mg / L, soluble organic matter concentration is about 151mg / L~203mg / L, ammonia nitrogen concentration is about 5mg / L~9mg / L, and perfluoroalkyl compound concentration is about 56.3ng / L~123.7ng / L; the water quality characteristics of the obtained secondary treatment liquid are: sulfate ion concentration is about 4530mg / L~6270mg / L, soluble organic matter concentration is about 45mg / L~56mg / L, ammonia nitrogen concentration is about 1mg / L~3mg / L, and perfluoroalkyl compound concentration is about 29.1ng / L~56.1ng / L.

[0033] Preferably, the modified biochar catalyst is prepared by the following steps:

[0034] SA1: Select hemp stalks as biochar raw materials and wash them 2 to 3 times, prepare a calcium hydroxide solution with a mass fraction of 3% to 5%, soak the washed hemp stalks in the calcium hydroxide solution for 75 to 95 minutes, take them out and dry them, place the hemp stalks in a drying device and dry them for 90 to 105 minutes, and then cool them to room temperature;

[0035] SA2: placing the hemp stalks into a heating device, heating to 515°C to 603°C at a heating rate of 3°C / min to 5°C / min, maintaining the temperature of 515°C to 603°C for 45 minutes to 67 minutes, cooling to room temperature to obtain hemp stalk biochar, and grinding the cooled hemp stalk biochar into fine powder, and screening out hemp stalk biochar fine powder of 100 mesh to 200 mesh;

[0036] SA3: preparing a manganese nitrate solution with a concentration of 13% to 17% and a copper chloride solution with a concentration of 5% to 9% calculated on the basis of metal elements, mixing the manganese nitrate solution and the copper chloride solution in a volume ratio of 1:(3 to 4) to obtain a first mixed solution, adding 2 mL to 5 mL of triethyl phosphate with a concentration of 16 mol / L per liter of the first mixed solution, stirring at a stirring speed of 55 rpm to 65 rpm for 210 minutes to 275 minutes to obtain a second mixed solution;

[0037] SA4: mixing the hemp stalk biochar fine powder with the second mixed solution in a volume ratio of 1:(5-7), soaking the hemp stalk biochar fine powder in the second mixed solution for 530 minutes to 710 minutes, taking it out and drying it;

[0038] SA5: Place the dried hemp stalk biochar fine powder into the heating device, heat it to 235°C-241°C at a heating rate of 2°C / min-5°C / min, maintain it at 235°C-241°C for 45 minutes-58 minutes, continue to heat it to 332°C-347°C at a heating rate of 2°C / min-5°C / min, maintain it at 332°C-347°C for 118 minutes-137 minutes, and then cool it to room temperature to obtain the modified biochar catalyst.

[0039] Thus, the modified biochar catalyst was prepared according to the above steps, and the specific surface area of ​​the modified biochar catalyst can reach about 103m 2 / g~121.9m 2 / g, the metal loading rate (measured by weight method) can reach about 5% to 8%, which makes the modified biochar catalyst have better catalytic activity and adsorption capacity. In the ozone catalytic oxidation reaction, ozone can be effectively converted into hydroxyl radicals, laying a good foundation for the efficient removal of pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in nanofiltration concentrate.

[0040] 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 heating device. For example, in some exemplary embodiments, the drying device can be a drying oven, and its set temperature can be 105° C.; the heating device can be a muffle furnace.

[0041] It should be noted that the parameters given in the preparation process of the modified biochar catalyst are only exemplary, and these parameters should be reasonably set according to the water quality characteristics of the nanofiltration concentrate.

[0042] Furthermore, the volume ratio of the modified biochar catalyst to the ozone catalytic oxidation tower 12 is 82% to 87%. Thus, the catalytic efficiency can be significantly improved, the adsorption performance can be enhanced, the advanced oxidation process can be promoted, and the reaction conditions can be optimized, so that the nanofiltration concentrated water can be treated efficiently and economically.

[0043] Preferably, the residence time of the nanofiltration concentrated water in the ozone catalytic oxidation tower 12 is 51 minutes to 62 minutes. Thus, sufficient time is provided for ozone and the catalyst to react with pollutants such as organic matter, ammonia nitrogen, and perfluoroalkyl compounds in the nanofiltration concentrated water, thereby improving the removal efficiency of pollutants. Moreover, by maintaining a residence time of 51 minutes to 62 minutes, the operating energy consumption and operating cost of the ozone catalytic oxidation tower 12 can be reduced.

[0044] Further, the ozone source in the ozone catalytic oxidation tower 12 includes an oxygen source, and the ozone concentration in the ozone catalytic oxidation tower 12 includes 65g / m 3 ~80g / m 3 This can improve the ozone oxidation efficiency, enhance the pollutant removal effect, and reduce energy consumption and operating costs.

[0045] Preferably, the biochemical treatment of the primary treatment liquid to obtain the secondary treatment liquid includes: transporting the primary treatment liquid to an aerobic aeration reactor 22 for biochemical treatment to obtain the secondary treatment liquid; wherein a modified polyurethane filler is provided in the aerobic aeration reactor 22. Thus, by transporting the primary treatment liquid to the aerobic aeration reactor 22 provided with the modified polyurethane filler for biochemical treatment, the biodegradable pollutants in the nanofiltration concentrated water can be further degraded.

[0046] For example, in some exemplary embodiments, the aerobic aeration reactor 22 can be an aerobic aeration tank, in which a modified polyurethane filler is placed, and the filling rate of the modified polyurethane filler is 35% to 45%, the sludge concentration of the aerobic aeration tank is maintained at 4500 mg / L to 5300 mg / L, the concentration of dissolved oxygen is 4.1 mg / L to 5.6 mg / L, and the hydraulic retention time is 890 minutes to 1020 minutes.

[0047] In order to make the present invention more understandable, the process of treating nanofiltration concentrate using the method for treating nanofiltration concentrate provided in this embodiment is described as an example.

[0048] In this example, the water quality characteristics of the nanofiltration concentrated water are: sulfate ion concentration is 4530mg / L~6270mg / L, dissolved organic matter concentration is 234mg / L~343mg / L, ammonia nitrogen concentration is 12mg / L~19mg / L, and perfluoroalkyl compound concentration is 108.1ng / L~207.9ng / L. The treatment steps of the nanofiltration concentrated water are as follows:

[0049] First, the nanofiltration concentrated water is transported to the ozone catalytic oxidation tower 12 equipped with a modified biochar catalyst by a primary lift pump 11. The ozone catalytic oxidation tower 12 uses an oxygen source as an ozone source, and the ozone concentration is 65g / m 3 ~80g / m 3 , and the volume ratio of the modified biochar catalyst to the ozone catalytic oxidation tower 12 is 82% to 87%. After the nanofiltration concentrated water stays in the ozone catalytic oxidation tower 12 for 51 minutes to 62 minutes, a primary treatment liquid is obtained. Specifically, the sulfate ion concentration of the primary treatment liquid is 4530 mg / L to 6270 mg / L, the dissolved organic matter concentration is 151 mg / L to 203 mg / L, the ammonia nitrogen concentration is 5 mg / L to 9 mg / L, and the perfluoroalkyl compound concentration is 56.3 ng / L to 123.7 ng / L.

[0050] Specifically, in this example, the modified biochar catalyst is prepared by the following steps: selecting hemp stalks as biochar raw materials and washing them with tap water for 2 to 3 times, preparing a calcium hydroxide solution with a mass fraction of 3% to 5%, soaking the washed hemp stalks in the calcium hydroxide solution for 75 to 95 minutes, taking them out and drying them, placing the hemp stalks in a drying oven at 105°C for 90 to 105 minutes, and cooling them to room temperature; then placing the hemp stalks in a muffle furnace at 3°C / min to 5°C / min The method comprises the following steps: heating the biochar to 515°C to 603°C at a heating rate of 1:1, keeping the biochar at this temperature for 45 to 67 minutes, cooling the biochar to room temperature, and grinding the biochar into fine powder in a grinder, and selecting the biochar fine powder of 100 to 200 meshes; then, preparing a manganese nitrate solution with a concentration of 13% to 17% and a copper chloride solution with a concentration of 5% to 9% based on the metal element, mixing the manganese nitrate solution with the copper chloride solution in a volume ratio of 1:(3 to 4), and obtaining the biochar. A mixed solution is prepared, and 2 mL to 5 mL of 16 mol / L triethyl phosphate is added to each liter of the first mixed solution, triethyl phosphate is used as an inorganic dispersant of the first mixed solution, and the mixture is stirred at a stirring speed of 55 rpm to 65 rpm for 210 minutes to 275 minutes to obtain a second mixed solution; then the screened 100-200 mesh hemp stalk biochar fine powder is mixed with the second mixed solution at a volume ratio of 1: (5-7), and the hemp stalk biochar fine powder is added to the second mixed solution. After soaking in the solution for 530 to 710 minutes, take it out and dry it; finally, put the dried hemp stalk biochar powder into a muffle furnace, heat it to 235 to 241 degrees Celsius at a heating rate of 2 to 5 degrees Celsius per minute, roast it at this temperature for 45 to 58 minutes, and continue to heat it to 332 to 347 degrees Celsius at a heating rate of 2 to 5 degrees Celsius per minute. After roasting at this temperature for 118 to 137 minutes, cool it to room temperature to obtain the modified biochar catalyst. The specific surface area of ​​the modified biochar catalyst obtained can reach 103m 2 / g~121.9m 2 / g, the metal loading rate (measured by weight method) can reach 5% to 8%.

[0051] Then, the primary treatment liquid is transported to an aerobic aeration tank provided with a modified polyurethane filler by a secondary lift pump 21. The filling rate of the modified polyurethane filler is 35% to 45%, the sludge concentration of the aerobic aeration tank is maintained at 4500mg / L to 5300mg / L, the concentration of dissolved oxygen is 4.1mg / L to 5.6mg / L, the hydraulic retention time is 890 minutes to 1020 minutes, and the secondary treatment liquid is obtained after treatment in the aerobic aeration tank, and the secondary treatment liquid is discharged by a drainage pump 23. Specifically, the sulfate ion concentration of the secondary treatment liquid is 4530mg / L to 6270mg / L, the concentration of dissolved organic matter is 45mg / L to 56mg / L, the concentration of ammonia nitrogen is 1mg / L to 3mg / L, and the concentration of perfluoroalkyl compounds is 29.1ng / L to 56.1ng / 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 wastewater zero discharge system.

[0052] It can be seen that the method for treating nanofiltration concentrate provided by the present invention can be used to treat nanofiltration concentrate, which can efficiently remove pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrate, thereby reducing environmental pollution and helping to achieve resource recycling.

[0053] In order to facilitate further understanding of the present invention, the present invention will be described below with reference to two specific examples of treating nanofiltration concentrate using the method for treating nanofiltration concentrate provided by the present invention.

[0054] Example 1: The water quality characteristics of the nanofiltration concentrated water are: sulfate ion concentration is 4579 mg / L, dissolved organic matter concentration is 251 mg / L, ammonia nitrogen concentration is 13 mg / L, and perfluoroalkyl compound concentration is 115.4 ng / L. The treatment steps for the nanofiltration concentrated water are as follows:

[0055] First, the nanofiltration concentrated water is transported to the ozone catalytic oxidation tower 12 equipped with a modified biochar catalyst by a primary lift pump 11. The ozone catalytic oxidation tower 12 uses an oxygen source as an ozone source, and the ozone concentration is 68 g / m 3 , and the volume ratio of the modified biochar catalyst to the ozone catalytic oxidation tower 12 is 83%. After the nanofiltration concentrated water stays in the ozone catalytic oxidation tower 12 for 54 minutes, a primary treatment liquid is obtained. Specifically, the sulfate ion concentration of the primary treatment liquid is 4712 mg / L, the dissolved organic matter concentration is 168 mg / L, the ammonia nitrogen concentration is 6 mg / L, and the perfluoroalkyl compound concentration is 68.9 ng / L.

[0056] Specifically, in this example, the modified biochar catalyst is prepared by the following steps: selecting hemp stalks as biochar raw materials and washing them with tap water for 3 times, preparing a calcium hydroxide solution with a mass fraction of 3.5%, soaking the washed hemp stalks in the calcium hydroxide solution for 82 minutes, taking them out and drying them, placing the hemp stalks in a drying oven at 105°C for 95 minutes, and cooling them to room temperature; then placing the hemp stalks in a muffle furnace, heating them to 550°C at a heating rate of 4°C / min, keeping them at this temperature for 52 minutes, and cooling them to room temperature to obtain hemp stalk biochar, placing the hemp stalk biochar in a grinder and grinding them into fine powder, and screening out 120-mesh hemp stalk biochar fine powder; then, calculating the metal elements, preparing a 14% manganese nitrate solution and a 6% copper chloride solution, and mixing the manganese nitrate solution with the copper chloride in a volume ratio of 1:3. After the solutions are mixed, a first mixed solution is obtained, and 3 mL of triethyl phosphate with a concentration of 16 mol / L is added to each liter of the first mixed solution. Triethyl phosphate is used as an inorganic dispersant of the first mixed solution, and the mixture is stirred at a stirring speed of 58 rpm for 227 minutes to obtain a second mixed solution; then the screened 120-mesh hemp stalk biochar fine powder is mixed with the second mixed solution at a volume ratio of 1:5, and the hemp stalk biochar fine powder is soaked in the second mixed solution for 560 minutes, then taken out and dried; finally, the dried hemp stalk biochar fine powder is placed in a muffle furnace, heated to 238°C at a heating rate of 3°C / min, roasted at this temperature for 48 minutes, and continued to heat to 339°C at a heating rate of 3°C / min, roasted at this temperature for 125 minutes, and then cooled to room temperature to obtain the modified biochar catalyst. The specific surface area of ​​the modified biochar catalyst obtained can reach 112.4m 2 / g, the metal loading rate (detected by weight method) can reach 6%.

[0057] Then, the primary treatment liquid is transported to an aerobic aeration tank provided with modified polyurethane filler by a secondary lift pump 21. The filling rate of the modified polyurethane filler is 38%, the sludge concentration of the aerobic aeration tank is maintained at 4851 mg / L, the concentration of dissolved oxygen is 4.3 mg / L, the hydraulic retention time is 910 minutes, and the secondary treatment liquid is obtained after treatment in the aerobic aeration tank, and the secondary treatment liquid is discharged by a drainage pump 23. Specifically, the sulfate ion concentration of the secondary treatment liquid is 4632 mg / L, the concentration of dissolved organic matter is 48 mg / L, the concentration of ammonia nitrogen is 1.5 mg / L, and the concentration of perfluoroalkyl compounds is 32.1 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 the wastewater zero discharge system.

[0058] Example 2: The water quality characteristics of the nanofiltration concentrated water are: sulfate ion concentration is 5796 mg / L, dissolved organic matter concentration is 312 mg / L, ammonia nitrogen concentration is 17 mg / L, and perfluoroalkyl compound concentration is 179.3 ng / L. The treatment steps for the nanofiltration concentrated water are as follows:

[0059] First, the nanofiltration concentrated water is transported to the ozone catalytic oxidation tower 12 equipped with a modified biochar catalyst by a primary lift pump 11. The ozone catalytic oxidation tower 12 uses an oxygen source as an ozone source, and the ozone concentration is 76 g / m 3 , and the volume ratio of the modified biochar catalyst to the ozone catalytic oxidation tower 12 is 85%. After the nanofiltration concentrated water stays in the ozone catalytic oxidation tower 12 for 61 minutes, a primary treatment liquid is obtained. Specifically, the sulfate ion concentration of the primary treatment liquid is 5612 mg / L, the dissolved organic matter concentration is 187 mg / L, the ammonia nitrogen concentration is 8 mg / L, and the perfluoroalkyl compound concentration is 112.4 ng / L.

[0060] Specifically, in this example, the modified biochar catalyst is prepared by the following steps: selecting hemp stalks as biochar raw materials and washing them with tap water for 3 times, preparing a 5% by mass calcium hydroxide solution, soaking the washed hemp stalks in the calcium hydroxide solution for 86 minutes, taking them out and drying them, placing the hemp stalks in a drying oven at 105°C for 100 minutes, and cooling them to room temperature; then placing the hemp stalks in a muffle furnace, heating them to 580°C at a heating rate of 5°C / min, keeping them at this temperature for 62 minutes, and cooling them to room temperature to obtain hemp stalk biochar, placing the hemp stalk biochar in a grinder and grinding them into fine powder, and screening out 150 mesh hemp stalk biochar fine powder; then, calculating the metal elements, preparing a 16% manganese nitrate solution and an 8% copper chloride solution, and mixing the manganese nitrate solution with the copper chloride in a volume ratio of 1:4. After the solutions are mixed, a first mixed solution is obtained, and 5 mL of triethyl phosphate with a concentration of 16 mol / L is added to each liter of the first mixed solution. Triethyl phosphate is used as an inorganic dispersant of the first mixed solution, and the mixture is stirred at a stirring speed of 63 rpm for 260 minutes to obtain a second mixed solution; then the screened 150-mesh hemp stalk biochar fine powder is mixed with the second mixed solution at a volume ratio of 1:6, and the hemp stalk biochar fine powder is soaked in the second mixed solution for 660 minutes, then taken out and dried; finally, the dried hemp stalk biochar fine powder is placed in a muffle furnace, heated to 240°C at a heating rate of 4°C / min, roasted at this temperature for 54 minutes, and continued to be heated to 345°C at a heating rate of 5°C / min. After roasting at this temperature for 130 minutes, it is cooled to room temperature to obtain the modified biochar catalyst. The specific surface area of ​​the modified biochar catalyst obtained can reach 117.6 m 2 / g, the metal loading rate (detected by weight method) can reach 7%.

[0061] Then, the primary treatment liquid is transported to an aerobic aeration tank provided with modified polyurethane filler by a secondary lift pump 21. The filling rate of the modified polyurethane filler is 43%, the sludge concentration of the aerobic aeration tank is maintained at 5213 mg / L, the concentration of dissolved oxygen is 4.5 mg / L, the hydraulic retention time is 987 minutes, and the secondary treatment liquid is obtained after treatment in the aerobic aeration tank, and the secondary treatment liquid is discharged by a drainage pump 23. Specifically, the sulfate ion concentration of the secondary treatment liquid is 5514 mg / L, the concentration of dissolved organic matter is 51 mg / L, the concentration of ammonia nitrogen is 2.3 mg / L, and the concentration of perfluoroalkyl compounds is 44.6 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 the wastewater zero discharge system.

[0062] Embodiment 2

[0063] This embodiment provides a nanofiltration concentrated water treatment system. Figure 3 , Figure 3 This is a structural block diagram of the nanofiltration concentrated water treatment system provided in this embodiment. Figure 3 It can be seen that the treatment system includes an ozone catalytic oxidation module 1 and a biochemical module 2 which are arranged in sequence; the ozone catalytic oxidation module 1 is configured to transport the nanofiltration concentrated water to an ozone catalytic oxidation tower 12 provided with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treatment liquid; the biochemical module 2 is configured to perform biochemical treatment on the primary treatment liquid to obtain a secondary treatment liquid.

[0064] Since the nanofiltration brine treatment system provided in this embodiment belongs to the same inventive concept as the nanofiltration brine treatment method described in any of the above-mentioned embodiments, the nanofiltration brine treatment system provided in this embodiment has at least all the advantages of the nanofiltration brine treatment method provided in the above-mentioned embodiments. For the advantages of the nanofiltration brine treatment system provided in this embodiment, please refer to the relevant description of the beneficial effects of the nanofiltration brine treatment method provided in the above-mentioned embodiments, which will not be repeated here.

[0065] In summary, the method and system for treating nanofiltration concentrate provided by the present invention have the following advantages: the method for treating nanofiltration concentrate provided by the present invention comprises: conveying the nanofiltration concentrate to an ozone catalytic oxidation tower provided with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treatment liquid; and subjecting the primary treatment liquid to biochemical treatment to obtain a secondary treatment liquid. Thus, the method for treating nanofiltration concentrate provided by the present invention is to convey the nanofiltration concentrate to an ozone catalytic oxidation tower provided with a modified biochar catalyst for ozone catalytic oxidation treatment. The modified biochar catalyst has good physical properties and can effectively convert ozone into hydroxyl radicals in the ozone catalytic oxidation reaction, thereby being able to effectively degrade and adsorb pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrate, thereby being able to significantly reduce the organic load in the nanofiltration concentrate and improve the biodegradability of the nanofiltration concentrate, laying a good foundation for reducing the burden of subsequent biochemical treatment and improving the treatment efficiency of the nanofiltration concentrate. Then, by biochemically treating the nanofiltration concentrated water, pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrated water can be further removed. The nanofiltration concentrated water treatment method provided by the present invention can efficiently remove pollutants such as soluble organic matter, ammonia nitrogen and perfluoroalkyl compounds in the nanofiltration concentrated water, thereby reducing environmental pollution and facilitating the reuse of resources.

[0066] Furthermore, the biochemical treatment of the primary treatment liquid to obtain the secondary treatment liquid includes: transporting the primary treatment liquid to an aerobic aeration reactor for biochemical treatment to obtain the secondary treatment liquid; wherein the aerobic aeration reactor is provided with a modified polyurethane filler. Thus, the method for treating nanofiltration concentrated water provided by the present invention can further degrade biodegradable pollutants in the nanofiltration concentrated water by transporting the primary treatment liquid to an aerobic aeration reactor provided with a modified polyurethane filler for biochemical treatment.

[0067] Since the nanofiltration concentrate treatment system provided by the present invention belongs to the same inventive concept as the nanofiltration concentrate treatment method described in any of the above-mentioned items, the nanofiltration concentrate treatment system provided by the present invention at least has all the advantages of the nanofiltration concentrate treatment method provided by the present invention. For the advantages of the nanofiltration concentrate treatment system provided by the present invention, please refer to the relevant description of the beneficial effects of the nanofiltration concentrate treatment method provided by the present invention, which will not be repeated here.

[0068] 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 treating nanofiltration concentrated water, characterized in that: The processing method comprises: The nanofiltration concentrated water is transported to an ozone catalytic oxidation tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treated liquid; The primary treatment liquid is subjected to biochemical treatment to obtain a secondary treatment liquid.

2. The method for treating nanofiltration concentrated water according to claim 1, characterized in that: The modified biochar catalyst is prepared by the following steps: SA1: Select hemp stalks as biochar raw materials and wash them 2 to 3 times, prepare a calcium hydroxide solution with a mass fraction of 3% to 5%, soak the washed hemp stalks in the calcium hydroxide solution for 75 to 95 minutes, take them out and dry them, place the hemp stalks in a drying device and dry them for 90 to 105 minutes, and then cool them to room temperature; SA2: placing the hemp stalks into a heating device, heating to 515°C to 603°C at a heating rate of 3°C / min to 5°C / min, maintaining the temperature of 515°C to 603°C for 45 minutes to 67 minutes, cooling to room temperature to obtain hemp stalk biochar, and grinding the cooled hemp stalk biochar into fine powder, and screening out hemp stalk biochar fine powder of 100 mesh to 200 mesh; SA3: preparing a manganese nitrate solution with a concentration of 13% to 17% and a copper chloride solution with a concentration of 5% to 9% calculated on the basis of metal elements, mixing the manganese nitrate solution and the copper chloride solution in a volume ratio of 1:(3 to 4) to obtain a first mixed solution, adding 2 mL to 5 mL of triethyl phosphate with a concentration of 16 mol / L per liter of the first mixed solution, stirring at a stirring speed of 55 rpm to 65 rpm for 210 minutes to 275 minutes to obtain a second mixed solution; SA4: mixing the hemp stalk biochar fine powder with the second mixed solution in a volume ratio of 1:(5-7), soaking the hemp stalk biochar fine powder in the second mixed solution for 530 minutes to 710 minutes, taking it out and drying it; SA5: Place the dried hemp stalk biochar fine powder into the heating device, heat it to 235°C-241°C at a heating rate of 2°C / min-5°C / min, maintain it at 235°C-241°C for 45 minutes-58 minutes, continue to heat it to 332°C-347°C at a heating rate of 2°C / min-5°C / min, maintain it at 332°C-347°C for 118 minutes-137 minutes, and then cool it to room temperature to obtain the modified biochar catalyst.

3. The method for treating nanofiltration concentrated water according to claim 1, characterized in that: The volume ratio of the modified biochar catalyst to the ozone catalytic oxidation tower is 82% to 87%.

4. The method for treating nanofiltration concentrated water according to claim 1, characterized in that: The residence time of the nanofiltration concentrated water in the ozone catalytic oxidation tower ranges from 51 minutes to 62 minutes.

5. The method for treating nanofiltration concentrated water according to claim 1, characterized in that: The ozone source in the ozone catalytic oxidation tower includes an oxygen source, and the ozone concentration in the ozone catalytic oxidation tower includes 65g / m 3 ~80g / m 3 .

6. The method for treating nanofiltration concentrated water according to claim 1, characterized in that: The biochemical treatment of the primary treatment liquid to obtain the secondary treatment liquid comprises: The primary treatment liquid is transported to an aerobic aeration reactor for biochemical treatment to obtain a secondary treatment liquid; wherein a modified polyurethane filler is arranged in the aerobic aeration reactor.

7. The method for treating nanofiltration concentrated water according to claim 6, characterized in that: The volume ratio of the modified polyurethane filler to the aerobic aeration reactor is 35% to 45%.

8. The method for treating nanofiltration concentrate according to any one of claims 1 to 7, characterized in that: The nanofiltration concentrate includes steel nanofiltration concentrate, and the water quality of the steel nanofiltration concentrate is: sulfate ion concentration is 4530mg / L~6270mg / L, dissolved organic matter concentration is 234mg / L~343mg / L, ammonia nitrogen concentration is 12mg / L~19mg / L, and perfluoroalkyl compound concentration is 108.1ng / L~207.9ng / L.

9. The method for treating nanofiltration concentrate according to any one of claims 1 to 7, characterized in that: The water quality of the secondary treatment liquid is as follows: sulfate ion concentration is 4530mg / L-6270mg / L, dissolved organic matter concentration is 45mg / L-56mg / L, ammonia nitrogen concentration is 1mg / L-3mg / L, and perfluoroalkyl compound concentration is 29.1ng / L-56.1ng / L.

10. A nanofiltration concentrated water treatment system, characterized in that: The treatment system comprises an ozone catalytic oxidation module and a biochemical module arranged in sequence; The ozone catalytic oxidation module is configured to transport the nanofiltration concentrated water to an ozone catalytic oxidation tower equipped with a modified biochar catalyst for ozone catalytic oxidation treatment to obtain a primary treated liquid; The biochemical module is configured to perform biochemical treatment on the primary treatment liquid to obtain a secondary treatment liquid.

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