Composite carrier, method for the production and use thereof

Abstract

The application relates to the technical field of wastewater denitrification, and discloses a composite carrier as well as a preparation method and application thereof. The composite carrier comprises porous molybdenum disulfide, the porous structure of the molybdenum disulfide in-situ grows zirconium metal organic frameworks, and the surface of the molybdenum disulfide is loaded with graphene. The composite carrier can not only serve as a place for denitrification of microorganisms, but also can improve the denitrification efficiency of the microorganisms.

Description

Technical Field

[0001] This invention relates to the field of wastewater denitrification technology, and in particular to a composite carrier, its preparation method, and its application. Background Technology

[0002] Nitrogen removal from wastewater is the process of treating wastewater to remove nitrogen to prevent eutrophication. It is generally divided into two types: physicochemical methods and biological methods. Physicochemical methods include breakpoint oxidation, air stripping or steam stripping, and selective ion exchange. In practice, biological denitrification, involving nitrification and denitrification, is often used. First, under aerobic conditions, nitrifying bacteria in the wastewater oxidize nitrogen compounds to nitrates (nitrification stage). Then, under anoxic conditions (dissolved oxygen less than 0.5 mg / L), denitrifying bacteria in the wastewater reduce the nitrates to gaseous nitrogen and other final gaseous products, which are released into the atmosphere (denitrification stage). However, these two stages require significant amounts of air, consume energy for sludge recirculation, and require the addition of exogenous organic carbon sources, resulting in a slow denitrification rate and energy waste. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a composite carrier, its preparation method, and its application. The composite carrier in this invention can not only serve as a site for microbial denitrification but also improve the efficiency of microbial denitrification.

[0004] The present invention provides a composite carrier comprising a porous molybdenum disulfide, wherein a zirconium metal-organic framework is grown in situ in the porous structure of the molybdenum disulfide, and graphene is loaded on the surface of the molybdenum disulfide.

[0005] Furthermore, the surface of the composite carrier is also connected with carboxyl groups.

[0006] The present invention also provides a method for preparing the composite carrier, the method comprising:

[0007] Step S1: The porous molybdenum disulfide is immersed in a metal-organic framework precursor solution, subjected to hydrothermal treatment, washed, and dried to obtain an intermediate product.

[0008] Step S2: The intermediate product is placed in a chemical vapor deposition furnace for gas phase carbon deposition, and then treated by plasma-enhanced chemical vapor deposition. In plasma-enhanced chemical vapor deposition, oxygen is introduced for treatment. The oxygen flow rate, processing power, current and voltage are set during the treatment to obtain a composite carrier.

[0009] Furthermore, in step S1, the method for preparing the metal-organic framework material precursor solution includes: dissolving and dispersing zirconium oxychloride octahydrate and 1,3,5-pyromellitic acid in an organic solution and mixing them evenly.

[0010] Furthermore, the organic solution is composed of N,N-dimethylformamide and formic acid, wherein the ratio of N,N-dimethylformamide to formic acid is 1:1 by volume.

[0011] Furthermore, by mass, the ratio of zirconium oxychloride octahydrate to 1,3,5-pyromellitic acid is (0.5-1.5) parts : (0.5-1) parts.

[0012] Furthermore, the mass concentration of the zirconium oxychloride octahydrate in the organic solution is 0.5 g / 50 mL to 1.5 g / 50 mL.

[0013] Furthermore, in step S1, the mass concentration of molybdenum disulfide in the metal-organic framework precursor solution is 5 mg / mL to 10 mg / mL.

[0014] Furthermore, in step S1, the temperature of the hydrothermal reaction is 110℃-130℃, and the time of the hydrothermal reaction is 10h-14h.

[0015] Furthermore, in step S1, the specific washing process includes washing at least three times with N,N-dimethylformamide and methanol respectively.

[0016] Furthermore, in step S1, the drying temperature is 50℃-70℃, and the drying time is 11h-13h.

[0017] Furthermore, in step S2, the specific method for performing gaseous carbon deposition in the chemical vapor deposition furnace includes: placing the intermediate product into the chemical vapor deposition furnace, adjusting the gas flow rate of the gaseous carbon source to 100 mL / min-200 mL / min, the reaction temperature to 1300℃-1500℃, and the reaction time to 0.5 h-1 h.

[0018] Furthermore, the heating rate to reach the reaction temperature is 4℃ / min-6℃ / min.

[0019] Furthermore, the gaseous carbon includes one or more of methane, acetylene, and ethylene.

[0020] Furthermore, in step S2, the oxygen flow rate is 50mL / min-60mL / min, the processing power is 45W-55W, the current is no greater than 1A and greater than 0.5A, and the voltage is no greater than 100KV and greater than 1KV.

[0021] The present invention also provides the application of the composite carrier in activated sludge for wastewater denitrification.

[0022] The embodiments of the present invention have the following technical effects:

[0023] 1. Using the composite carrier obtained in this invention to mix with activated sludge can improve the efficiency of wastewater denitrification. Specifically, molybdenum disulfide has piezoelectric self-driving properties. During wastewater treatment, it can generate electrons under the action of hydraulic disturbance and vibration. These electrons can be transferred to the surface of microbial cells or nitrate nitrogen molecules, promoting the chemical reduction of nitrate nitrogen and biological denitrification. In addition, the porous structure of molybdenum disulfide used in this invention not only helps to increase the specific surface area of ​​molybdenum disulfide, thus facilitating the loading of more microorganisms in its porous structure, but also facilitates the rapid transfer of generated electrons to the surface of microbial cells, further improving the efficiency of biological denitrification. On this basis, in order to prevent the porous structure of molybdenum disulfide from collapsing under hydraulic action, a zirconium metal-organic framework is generated in situ in the porous structure. First, the zirconium metal-organic framework serves as a framework structure to support molybdenum disulfide. Second, it facilitates the transfer of electrons in the porous structure, thus facilitating the reception of electrons by more microbial cell surfaces in the porous structure. Third, the zirconium metal-organic framework is corrosion-resistant. Building upon this foundation, the present invention further incorporates graphene loaded onto the surface of molybdenum disulfide. Graphene not only facilitates the outward transfer of electrons generated by molybdenum disulfide, allowing them to be utilized by unadsorbed microbial surfaces and nitrate nitrogen molecules in the sludge, but the graphene within the composite carriers also forms electron transport pathways within the activated sludge. Thus, the graphene and zirconium metal-organic framework form an electron transport route centered on molybdenum disulfide, with electrons radiating outwards from the molybdenum disulfide core, creating an electron transport network within the activated sludge. Finally, carboxyl groups are attached to the surface of the composite carriers. These carboxyl groups not only reduce aggregation between the composite carriers but also facilitate the adsorption of nitrate nitrogen molecules, thereby enhancing electron transport efficiency.

[0024] 2. In this invention, graphene loaded on the surface of molybdenum disulfide can promote the transfer of electrons to the surroundings. The amount of electrons generated by molybdenum disulfide is directly related to the hydraulic force transferred on the surface of molybdenum disulfide. Therefore, it is necessary to control the amount of graphene loaded on the surface of molybdenum disulfide to reduce the influence of graphene on the amount of electrons generated by molybdenum disulfide while ensuring the electron transfer efficiency. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] In a first aspect, some embodiments of the present invention provide a composite carrier comprising a porous molybdenum disulfide, wherein a zirconium metal-organic framework is grown in situ in the porous structure of the molybdenum disulfide, and graphene is loaded on the surface of the molybdenum disulfide.

[0027] In some embodiments, the surface of the composite carrier is further connected with carboxyl groups.

[0028] Secondly, some embodiments of the present invention also provide a method for preparing the composite carrier, the method comprising:

[0029] Step S1: The porous molybdenum disulfide is immersed in a metal-organic framework precursor solution, subjected to hydrothermal treatment, washed, and dried to obtain an intermediate product.

[0030] Step S2: The intermediate product is placed in a chemical vapor deposition furnace for gas phase carbon deposition, and then treated by plasma-enhanced chemical vapor deposition. In plasma-enhanced chemical vapor deposition, oxygen is introduced for treatment. The oxygen flow rate, processing power, current and voltage are set during the treatment to obtain a composite carrier.

[0031] In some embodiments, the preparation method of the metal-organic framework material precursor solution in step S1 includes: dissolving and dispersing zirconium oxychloride octahydrate and 1,3,5-pyromellitic acid in an organic solution and mixing them evenly.

[0032] In some embodiments, the organic solution is composed of N,N-dimethylformamide and formic acid, wherein the ratio of N,N-dimethylformamide to formic acid is 1:1 by volume.

[0033] In some embodiments, the ratio of zirconium oxychloride octahydrate to 1,3,5-pyromellitic acid, by mass, is (0.5-1.5) parts:(0.5-1) parts.

[0034] In some embodiments, the mass concentration of the zirconium oxychloride octahydrate in the organic solution is 0.5 g / 50 mL to 1.5 g / 50 mL.

[0035] In some embodiments, in step S1, the mass concentration of molybdenum disulfide in the metal-organic framework precursor solution is 5 mg / mL-10 mg / mL.

[0036] In some embodiments, in step S1, the temperature of the hydrothermal reaction is 110℃-130℃, and the time of the hydrothermal reaction is 10h-14h.

[0037] In some embodiments, the washing process in step S1 includes washing at least three times with N,N-dimethylformamide and methanol respectively.

[0038] In some embodiments, in step S1, the drying temperature is 50℃-70℃ and the drying time is 11h-13h.

[0039] In some embodiments, the specific method for performing gaseous carbon deposition in the chemical vapor deposition furnace in step S2 includes: placing the intermediate product into the chemical vapor deposition furnace, adjusting the gas flow rate of the gaseous carbon source to 100 mL / min-200 mL / min, the reaction temperature to 1300℃-1500℃, and the reaction time to 0.5 h-1 h.

[0040] In some embodiments, the heating rate to reach the reaction temperature is 4°C / min to 6°C / min.

[0041] In some embodiments, the gaseous carbon includes one or more of methane, acetylene, and ethylene.

[0042] In some embodiments, in step S2, the oxygen flow rate is 50 mL / min-60 mL / min, the processing power is 45 W-55 W, the current is no more than 1 A and greater than 0.5 A, and the voltage is no more than 100 KV and greater than 1 KV.

[0043] Thirdly, some embodiments of the present invention also provide the application of the composite carrier in activated sludge for wastewater denitrification.

[0044] The following detailed explanation is provided with reference to specific embodiments and comparative examples:

[0045] Example 1:

[0046] (1) Preparation of precursor solution for metal-organic framework material: Weigh 1.2 g zirconium oxychloride octahydrate and 0.8 g 1,3,5-pyromellitic acid and dissolve and disperse them in 50 mL organic solution (the organic solution is composed of formic acid and N,N-dimethylformamide, and the volume ratio of formic acid and N,N-dimethylformamide is 1:1) and sonicate for 1.5 hours.

[0047] (2) Preparation of porous molybdenum disulfide: Weigh 0.1 mmol of ammonium molybdate tetrahydrate and add it to a 100 mL beaker. Add 10 mL of deionized water and dissolve the drug completely in a 50 °C water bath. Add 7 mmol of thiourea and repeat the heating process to dissolve the precursor solution into a colorless and transparent solution. Add 7 mmol of 350 nm diameter silica to the beaker and sonicate for 30 min to ensure uniform dispersion of silica in the precursor solution. Then, stir at room temperature for 12 h to ensure sufficient contact between the ions in the aqueous phase and the surface of the silica microspheres. Finally, freeze the resulting pale blue suspension in a refrigerator for 12 h, and then dry the frozen solid sample in a freeze dryer (-40 °C, 55 Pa) for 15 h. Scrape off the dried sample, grind it evenly, and calcine it in a tube furnace at 500 °C for 4 h under a nitrogen atmosphere. After the reaction was completed, the sample was treated with 2M sodium hydroxide aqueous solution for 20 hours to remove the silica microspheres. Finally, the black powder sample was washed with deionized water by multiple filtrations and dried in an oven at 50°C to obtain porous molybdenum disulfide. In this invention, the porous molybdenum disulfide can also be commercially available.

[0048] (3) The porous molybdenum disulfide was immersed in a metal-organic framework precursor solution with a mass concentration of 8 mg / mL. After mixing, the mixture was placed in an autoclave at 130°C and sealed for hydrothermal treatment for 13 h. The mixture was then washed three times with N,N-dimethylformamide and methanol, and dried at 50°C for 12 h to obtain the intermediate product.

[0049] (4) The intermediate product was placed in a chemical vapor deposition furnace for gaseous carbon deposition. The methane gas flow rate was adjusted to 150 mL / min, the reaction temperature to 1400℃, the heating rate to reach the reaction temperature to be 5℃ / min, and the reaction time to be 0.8 h. Then, it was treated by plasma-enhanced chemical vapor deposition. In plasma-enhanced chemical vapor deposition, oxygen was introduced for treatment. The oxygen flow rate was set to 55 mL / min, the treatment power to be 50 W, the current to be 0.8 A, and the voltage to be 2 KV to obtain a composite carrier.

[0050] Example 2:

[0051] The preparation method of Example 2 is the same as that of Example 1. However, when performing gas phase carbon deposition in the chemical vapor deposition furnace in Example 2, the parameters used are as follows: the methane gas flow rate is adjusted to 200 mL / min, the reaction temperature is 1500℃, the heating rate to reach the reaction temperature is 4℃ / min, and the reaction time is 1 h. Other parameters in the preparation method of Example 2 are the same as those in Example 1.

[0052] Example 3:

[0053] The preparation method of Example 3 is the same as that of Example 1. However, when performing gas phase carbon deposition in the chemical vapor deposition furnace in Example 3, the parameters used are as follows: the methane gas flow rate is adjusted to 100 mL / min, the reaction temperature is 1400℃, the heating rate to reach the reaction temperature is 6℃ / min, and the reaction time is 0.5 h. Other parameters in the preparation method of Example 3 are the same as those in Example 1.

[0054] Example 4:

[0055] The preparation method of Example 4 is the same as that of Example 1. However, when performing gas phase carbon deposition in the chemical vapor deposition furnace in Example 4, the parameters used are as follows: the methane gas flow rate is adjusted to 200 mL / min, the reaction temperature is 1400℃, the heating rate to reach the reaction temperature is 5℃ / min, and the reaction time is 0.8 h. Other parameters in the preparation method of Example 3 are the same as those in Example 1.

[0056] Comparative Example 1:

[0057] Porous molybdenum disulfide was placed in a chemical vapor deposition (CVD) furnace for CVD carbon deposition. The methane flow rate was adjusted to 150 mL / min, the reaction temperature to 1400 °C, the temperature rise rate to reach the reaction temperature to be 5 °C / min, and the reaction time to be 0.8 h. Subsequently, a plasma-enhanced CVD process was performed, in which oxygen was introduced. The oxygen flow rate was set to 55 mL / min, the processing power to be 50 W, the current to be 0.8 A, and the voltage to be 2 kV to obtain the carrier.

[0058] Comparative Example 2:

[0059] (1) Preparation of precursor solution for metal-organic framework material: Weigh 1.2 g zirconium oxychloride octahydrate and 0.8 g 1,3,5-pyromellitic acid and dissolve and disperse them in 50 mL organic solution (the organic solution is composed of formic acid and N,N-dimethylformamide, and the volume ratio of formic acid and N,N-dimethylformamide is 1:1) and sonicate for 1.5 hours.

[0060] (2) The porous molybdenum disulfide was immersed in a metal-organic framework precursor solution with a mass concentration of 8 mg / mL. After mixing, the mixture was placed in an autoclave at 130°C and sealed for hydrothermal treatment for 13 h. The mixture was then washed three times with N,N-dimethylformamide and methanol, and dried at 50°C for 12 h to obtain the intermediate product.

[0061] (3) The intermediate product was treated by plasma-enhanced chemical vapor precipitation. Oxygen was introduced into the plasma-enhanced chemical vapor precipitation process. The oxygen flow rate was set to 55 mL / min, the processing power to 50 W, the current to 0.8 A, and the voltage to 2 KV to obtain the carrier.

[0062] Comparative Example 3:

[0063] (1) Preparation of precursor solution for metal-organic framework material: 1.2 g of zirconium oxychloride octahydrate and 0.8 g of 1,3,5-pyromellitic acid were weighed and dissolved and dispersed in 50 mL of organic solution (the organic solution is composed of formic acid and N,N-dimethylformamide, with a volume ratio of formic acid to N,N-dimethylformamide of 1:1) and ultrasonically stirred for 1.5 hours.

[0064] (2) The porous molybdenum disulfide was immersed in a metal-organic framework precursor solution with a mass concentration of 8 mg / mL. After mixing, the mixture was placed in an autoclave at 130°C and sealed for hydrothermal treatment for 13 h. The mixture was then washed three times with N,N-dimethylformamide and methanol, and dried at 50°C for 12 h to obtain the intermediate product.

[0065] (3) The intermediate product was placed in a chemical vapor deposition furnace for gas phase carbon deposition. The methane gas flow rate was adjusted to 150 mL / min, the reaction temperature was 1400℃, the heating rate to reach the reaction temperature was 5℃ / min, and the reaction time was 0.8 h to obtain the support.

[0066] Comparative Example 4:

[0067] The preparation method of Comparative Example 4 is the same as that of Example 1. However, when performing gas phase carbon deposition in the chemical vapor deposition furnace in Comparative Example 4, the parameters used are as follows: the methane gas flow rate is adjusted to 90 mL / min, the reaction temperature is 1300℃, the heating rate to reach the reaction temperature is 6℃ / min, and the reaction time is 0.5 h. Other parameters in the preparation method of Comparative Example 4 are the same as those in Example 1.

[0068] Comparative Example 5:

[0069] The preparation method of Comparative Example 5 is the same as that of Example 1. However, when performing gas phase carbon deposition in the chemical vapor deposition furnace in Comparative Example 5, the parameters used are as follows: the methane gas flow rate is adjusted to 250 mL / min, the reaction temperature is 1500 °C, the heating rate to reach the reaction temperature is 4 °C / min, and the reaction time is 1 h. Other parameters in the preparation method of Comparative Example 5 are the same as those in Example 1.

[0070] The carriers obtained from the examples and comparative examples were tested:

[0071] The carrier and activated sludge were mixed at a ratio of 1g carrier to 1000mL activated sludge, and then placed in the biological treatment system. The volume ratio of the mixed carrier and activated sludge to the volume of the biological treatment system was 1:80, with a volume of 1L. The system simulated biological denitrification of wastewater, with an influent TN of 60mg / L, a retention time of 14 hours, and a temperature of room temperature (approximately 22℃). The supernatant was collected from the effluent for nitrogen-related index testing. The activated sludge was sourced from the facultative anaerobic biological treatment section of the chemical wastewater biological treatment system at Wuxi Hynix Semiconductor Materials Co., Ltd.

[0072] Results and Analysis:

[0073] Table 1. Results of nitrogen-containing wastewater treatment in the examples and comparative examples.

[0074] — Inlet TN Outflow TN Total nitrogen removal rate (%) Example 1 60 3 95.00％ Example 2 60 4.3 92.83％ Example 3 60 4.5 92.50％ Example 4 60 5.5 90.83％ Comparative Example 1 60 30 50.00％ Comparative Example 2 60 28 53.33％ Comparative Example 3 60 16 73.33％ Comparative Example 4 60 13 78.33％ Comparative Example 5 60 17 71.67％

[0075] The present invention successfully obtained a composite carrier for wastewater denitrification. The composite carrier contains porous molybdenum disulfide, which exhibits piezoelectric self-driving properties. During wastewater treatment, it generates electrons under hydraulic disturbance and vibration. These electrons can be transferred to the surface of microbial cells or nitrate nitrogen molecules, promoting the chemical reduction and biological denitrification of nitrate nitrogen, thereby improving the wastewater denitrification rate. Comparison of Examples 1-4 with Comparative Examples 1-5 reveals that the composite carrier obtained by the present invention has significant advantages in wastewater denitrification. Wastewater treated with the composite carrier of the present invention shows a significant reduction in nitrogen content.

[0076] Because a porous molybdenum disulfide structure is used, its porous structure increases the specific surface area of ​​molybdenum disulfide, which is beneficial for adsorbing many microorganisms loaded within its porous structure, thereby improving the efficiency of biological denitrification. However, the porous structure of molybdenum disulfide can collapse due to hydraulic forces. Therefore, in this invention, a zirconium metal-organic framework structure is also generated in situ within the porous structure. This improves the stability of the porous structure and allows for electron transfer, enabling more microbial cell surfaces within the porous structure to receive electrons, further enhancing the denitrification capacity of wastewater. This was verified by comparing Examples 1-4 with Comparative Example 1. When there is no zirconium metal-organic framework in the porous structure, Comparative Example 1 may have experienced structural collapse, and the electron transport capacity within the porous structure is reduced. Therefore, the nitrogen conversion rate of Comparative Example 1 is significantly lower than that of Examples 1-4.

[0077] Graphene is loaded onto the surface of the porous molybdenum disulfide structure of this invention. Graphene not only transfers electrons generated by molybdenum disulfide outwards, allowing them to be utilized by unadsorbed microbial surfaces and nitrate nitrogen molecules in the sludge, but the graphene between the composite carriers also forms electron transport pathways within the activated sludge. Furthermore, graphene and the zirconium metal-organic framework form an electron transport route centered on molybdenum disulfide, with electrons transferring outwards from the molybdenum disulfide core. This creates an electron transport network within the activated sludge, which enhances electron transport throughout the entire activated sludge, thereby increasing the nitrogen conversion rate in the wastewater. Comparison of Examples 1-4 with Comparative Example 2 verifies that graphene can improve nitrogen conversion in wastewater.

[0078] When the graphene loading on the molybdenum disulfide surface is low, the electron transport network is poorly constructed, hindering electron transport in the sludge. The amount of electrons generated by molybdenum disulfide is directly related to the hydraulic conductivity on its surface. However, a higher graphene loading affects hydraulic conductivity, reducing the amount of electrons generated by molybdenum disulfide and impacting nitrogen conversion in wastewater. This can be verified by comparing Examples 1-4 with Comparative Examples 4-5. Therefore, only when the graphene content on the molybdenum disulfide surface is appropriate can the impact of graphene on electron generation in molybdenum disulfide be reduced while ensuring electron transport efficiency.

[0079] Further comparison of Examples 1-4 showed that when the methane flow rate increases, the reaction time can be increased, the heating rate can be decreased, and the reaction temperature can be increased. Conversely, when the methane flow rate decreases, the reaction time can be reduced, the heating rate can be increased, and the reaction temperature can be decreased. This promotes uniform loading of graphene, reduces side reactions, and thus helps graphene to exert its function.

[0080] Finally, carboxyl groups were also attached to the composite carrier. The carboxyl groups can not only reduce the aggregation between composite carriers, but also facilitate the adsorption of nitrate nitrogen molecules by the composite carrier, thereby improving the efficiency of electron transfer. This was verified by comparing Examples 1-4 with Comparative Example 3.

[0081] In summary, the composite carrier obtained by this invention can not only serve as a site for microbial denitrification, but also improve the efficiency of microbial denitrification.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. The application of a composite carrier in activated sludge for wastewater denitrification, characterized in that, The composite carrier includes a porous molybdenum disulfide structure, in which a zirconium metal-organic framework is grown in situ, and graphene is loaded on the surface of the molybdenum disulfide. The surface of the composite carrier is also connected with carboxyl groups; The method for preparing the composite carrier includes: Step S1: The porous molybdenum disulfide is immersed in a metal-organic framework precursor solution, subjected to hydrothermal treatment, washed, and dried to obtain an intermediate product. Step S2: The intermediate product is placed in a chemical vapor deposition furnace for gas phase carbon deposition, and then treated by plasma-enhanced chemical vapor deposition. Oxygen is introduced into the plasma-enhanced chemical vapor deposition process. The oxygen flow rate, processing power, current and voltage are set during the process to obtain a composite carrier. In step S1, the preparation method of the metal-organic framework material precursor solution includes: dissolving and dispersing zirconium oxychloride octahydrate and 1,3,5-pyromellitic acid in an organic solution and mixing them evenly; The organic solution is composed of N,N-dimethylformamide and formic acid, and the ratio of N,N-dimethylformamide to formic acid is 1:1 by volume. The ratio of zirconium oxychloride octahydrate to 1,3,5-pyromellitic acid by mass is (0.5-1.5) parts : (0.5-1) parts; The zirconium oxychloride octahydrate has a mass concentration of 0.5 g / 50 mL to 1.5 g / 50 mL in the organic solution; In step S2, the specific method for performing gaseous carbon deposition in the chemical vapor deposition furnace includes: placing the intermediate product into the chemical vapor deposition furnace, adjusting the gas flow rate of the gaseous carbon source to 100 mL / min-200 mL / min, the reaction temperature to 1300℃-1500℃, and the reaction time to 0.5 h-1 h. The heating rate to reach the reaction temperature is 4℃ / min-6℃ / min; The gaseous carbon includes one or more of methane, acetylene, and ethylene.

2. The application of the composite carrier according to claim 1 in activated sludge for wastewater denitrification, characterized in that, In step S1, the mass concentration of molybdenum disulfide in the metal-organic framework precursor solution is 5 mg / mL-10 mg / mL. In step S1, the temperature of the hydrothermal reaction is 110℃-130℃, and the time of the hydrothermal reaction is 10h-14h. The specific washing process includes washing at least three times with N,N-dimethylformamide and methanol respectively. In step S1, the drying temperature is 50℃-70℃, and the drying time is 11h-13h.

3. The application of the composite carrier according to claim 1 in activated sludge for wastewater denitrification, characterized in that, In step S2, the oxygen flow rate is 50 mL / min-60 mL / min, the processing power is 45 W-55 W, the current is no more than 1 A and greater than 0.5 A, and the voltage is no more than 100 KV and greater than 1 KV.