Application of composite modified activated carbon in rapid formation of enhanced aerobic granular sludge
By preparing composite modified activated carbon, loading calcium and magnesium oxides and forming a polydopamine film, the problem of long start-up cycle of aerobic granular sludge is solved, realizing rapid and stable start-up and efficient sewage treatment, which is suitable for municipal and industrial wastewater treatment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Filing Date
- 2026-05-06
- Publication Date
- 2026-07-10
AI Technical Summary
The long start-up period of aerobic granular sludge granulation limits its engineering application, and improper parameter control can easily lead to sludge floc disintegration or excessive proliferation of filamentous bacteria, making it difficult to achieve rapid and stable start-up.
By using composite modified activated carbon, a porous activated carbon material with surface functional groups was prepared through steps such as heating and stirring, ultrasonic treatment, calcination and modification with dopamine hydrochloride. Calcium and magnesium oxides were loaded to form a polydopamine film, which promoted microbial aggregation and adhesion and shortened the granulation cycle.
It significantly shortens the formation cycle of aerobic granular sludge, improves wastewater treatment efficiency, and is suitable for municipal and industrial wastewater treatment, with broad application prospects.
Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment technology, specifically to the application of a composite modified activated carbon in enhancing the rapid formation of aerobic granular sludge. Background Technology
[0002] Aerobic granular sludge (AGS) technology is a novel biological wastewater treatment process based on microbial self-aggregation. This technology optimizes reactor hydraulic conditions and operating parameters, enabling dispersed microorganisms to form granular sludge aggregates with regular shapes, dense structures, and excellent settling properties in an aerobic environment. Compared to traditional activated sludge flocs, aerobic granular sludge offers significant advantages, including high biomass concentration, high sludge-water separation efficiency, strong simultaneous nitrogen and phosphorus removal capabilities, and a compact reactor structure. It can couple multiple functions such as carbon oxidation, nitrification, denitrification, and biological phosphorus removal within a single reactor, significantly reducing the footprint and energy consumption of wastewater treatment facilities. In recent years, with the development of sequencing batch reactors (SBRs) and their improved processes, aerobic granular sludge technology has shown broad application prospects in the treatment of municipal wastewater, high-concentration organic wastewater, and industrial wastewater.
[0003] Despite the numerous technological advantages of aerobic granular sludge technology, its industrial application has long been constrained by the lengthy start-up period. During reactor start-up, the inoculated flocculent activated sludge needs to be gradually acclimated and cultivated into structurally stable granular sludge, a process that typically requires several months of operation. This significantly prolongs the engineering commissioning cycle and increases operating costs during the start-up phase. The main reason for the slow start-up of granular sludge is the high sensitivity of the microbial self-aggregation process to operating parameters such as hydraulic shear force, substrate selective pressure, and settling time. Improper parameter control can easily lead to sludge floc disintegration or excessive proliferation of filamentous bacteria, hindering granule formation. Furthermore, differences in water quality characteristics and microbial community structure make the granular start-up process difficult to predict and control, further exacerbating the uncertainty and technical risks of reactor start-up.
[0004] Therefore, shortening the granulation start-up cycle of aerobic granular sludge and achieving rapid and stable reactor start-up have become key technical requirements for promoting the engineering application of this technology. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide an application of composite modified activated carbon in enhancing the rapid formation of aerobic granular sludge.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides an application of composite modified activated carbon in enhancing the rapid formation of aerobic granular sludge.
[0007] In the technical solution disclosed in this invention, the preparation method of the composite modified activated carbon is as follows: S1. Add activated carbon to an acid solution, heat and stir, then filter, wash and dry to obtain pretreated activated carbon; S2. The pretreated activated carbon is impregnated in a mixed solution containing calcium chloride and magnesium nitrate, ultrasonically treated, and then filtered, washed, dried, calcined and ground to obtain the activated carbon composite material. S3. Place the activated carbon composite material in a hydrochloric acid dopamine solution, adjust the pH of the solution to 8-9, stir the reaction, and after the reaction is completed, filter, wash and dry to obtain the composite modified activated carbon.
[0008] In the technical solution disclosed in this invention, in step S1, the solid-liquid ratio of activated carbon and acid solution is 1g:10-20mL. For example, 1g:10mL, 1g:12mL, 1g:15mL, 1g:16mL, 1g:18mL, and 1g:20mL can be selected, but it is not limited to the listed values. Other unlisted values within the range are also applicable.
[0009] Specifically, the acid solution is selected from nitric acid solution, sulfuric acid solution or hydrochloric acid solution, and the concentration of the acid solution is 0.5-2 mol / L.
[0010] In the technical solution disclosed in this invention, in step S1, the heating and stirring temperature is 60-80℃, for example, 60℃, 65℃, 70℃, 75℃, or 80℃ can be selected; the heating and stirring time is 2-4h, for example, 2h, 2.5h, 3h, 3.5h, or 4h can be selected, but it is not limited to the listed values, and other unlisted values within the range are also applicable.
[0011] In the technical solution disclosed in this invention, in step S2, the mass ratio of pretreated activated carbon, calcium chloride and magnesium nitrate is 10-15:3-6:3-6.
[0012] In the technical solution disclosed in this invention, in step S2, the calcination temperature is 400-550℃, for example, 400℃, 420℃, 450℃, 460℃, 480℃, 500℃, 520℃, and 550℃ can be selected; the calcination time is 2-3h, for example, 2h, 2.5h, and 3h can be selected, but it is not limited to the listed values. Other unlisted values within the range are also applicable.
[0013] In the technical solution disclosed in this invention, in step S3, the ratio of activated carbon composite material to dopamine hydrochloride solution is 5-10g:100mL. For example, 5g:100mL, 6g:100mL, 7g:100mL, 8g:100mL, 9g:100mL, and 10g:100mL can be selected, but it is not limited to the listed values. Other unlisted values within the range are also applicable.
[0014] In the technical solution disclosed in this invention, in step S3, the concentration of the dopamine hydrochloride solution is 1-3 g / L. For example, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, or 3 g / L can be selected, but it is not limited to the listed values. Other unlisted values within the range are also applicable.
[0015] In the technical solution disclosed in this invention, in step S3, the reaction is stirred for 12-24 hours under room temperature and light-protected conditions. For example, 12 hours, 15 hours, 18 hours, 21 hours, or 24 hours can be selected, but it is not limited to the listed values. Other unlisted values within the range are also applicable.
[0016] In the technical solution disclosed in this invention, the ratio of composite modified activated carbon to aerobic granular sludge is 4-8g:100mL. For example, 4g:100mL, 5g:100mL, 6g:100mL, 7g:100mL, and 8g:100mL can be selected, but it is not limited to the listed values. Other unlisted values within the range are also applicable.
[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The composite modified activated carbon provided by the present invention can significantly shorten the granulation cycle when applied to enhance the rapid formation of aerobic granular sludge. At the same time, the porous structure and surface functional groups of the composite modified activated carbon can help adsorb pollutants in sewage, forming a synergy with the biodegradation of aerobic granular sludge, further improving the sewage treatment efficiency. It is suitable for various municipal sewage and industrial wastewater treatment scenarios and has broad industrial application prospects and practical value.
[0018] (2) The composite modified activated carbon provided by the present invention forms uniformly dispersed calcium and magnesium oxide crystal nuclei on the surface and in the pores of activated carbon by co-loading calcium chloride and magnesium nitrate and calcination treatment. This can efficiently neutralize the negative charge on the sludge surface and reduce electrostatic repulsion. At the same time, it stimulates microorganisms to secrete extracellular polymers (EPS), providing strong crystal nuclei support for the initial aggregation of aerobic granular sludge. Compared with loading calcium oxide or magnesium oxide alone, it is easier to induce microbial aggregation and further shorten the granulation cycle.
[0019] (3) The present invention modifies activated carbon composite material with hydrochloric acid dopamine, and forms a polydopamine film on the surface of the composite material, which significantly improves the biocompatibility and microbial adhesion ability of the composite modified activated carbon, accelerates the colonization and proliferation of microorganisms on the carrier surface, and works together with calcium and magnesium oxides to greatly shorten the formation cycle of aerobic granular sludge and improve the granule formation efficiency. Detailed Implementation
[0020] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.
[0021] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.
[0022] The aerobic activated sludge used in this embodiment of the invention comes from the aeration tank of an urban wastewater treatment plant, with an MLSS concentration of 4500 mg / L; the activated carbon has a mesh size of 200 mesh.
[0023] Example 1 The application of a composite modified activated carbon in enhancing the rapid formation of aerobic granular sludge, the specific steps are as follows: S1. Set up a sequencing batch reactor (SBR) with an effective reactor volume of 2L.
[0024] S2, both reactors are filled with aerobic activated sludge MLSS=4500mg / L.
[0025] S3. Add 5g of composite modified activated carbon and 100mL of aerobic activated sludge to each 1L of effective reactor volume, adjust the pH to 7.5, and control the temperature at 25℃. The preparation method of the composite modified activated carbon is as follows: (1) Add 10g of activated carbon to 100mL of 1mol / L nitric acid solution, heat and stir at 80℃ for 2h, then filter, wash and dry to obtain pretreated activated carbon; (2) 10g of pretreated activated carbon was impregnated in 100mL of a mixed solution containing 3g calcium chloride and 3g magnesium nitrate, ultrasonically treated at 300W for 60min, then filtered, washed and dried, calcined at 550℃ for 2h, and ground through a 200-mesh sieve to obtain activated carbon composite material. (3) Place 5g of activated carbon composite material in 100mL of 2g / L hydrochloric acid dopamine solution, adjust the pH of the solution to 8.5, stir and react for 12h at room temperature and in the dark. After the reaction is completed, filter, wash and dry to obtain composite modified activated carbon.
[0026] S4. Operating cycle: 240 minutes / cycle, including water intake, aeration reaction, settling and drainage stages, with the settling time gradually shortened from 30 minutes to 3 minutes.
[0027] S5. Using sodium acetate as the carbon source, COD is approximately 800 mg / L, ammonia nitrogen is approximately 45 mg / L, TP is approximately 4 mg / L, and Ca... 2+ 10 mg / L, Mg 2+ The concentration is 10 mg / L.
[0028] S6. Systematically investigate the formation process and long-term operational stability of aerobic granular sludge.
[0029] When the entire operation cycle was 34 days, the concentration of ammonia nitrogen was detected to be 0.24 mg / L, which shows that the method provided in this embodiment has a good denitrification effect, and the proportion of aerobic granular sludge with a particle size >1 mm in the system was 94.3%.
[0030] Example 2 The application of a composite modified activated carbon in enhancing the rapid formation of aerobic granular sludge, the specific steps are as follows: S1. Set up a sequencing batch reactor (SBR) with an effective reactor volume of 2L.
[0031] S2, both reactors are filled with aerobic activated sludge MLSS=4500mg / L.
[0032] S3. Add 4g of composite modified activated carbon and 100mL of aerobic activated sludge to each 1L of effective reactor volume, adjust the pH to 7.5, and control the temperature at 25℃. The preparation method of the composite modified activated carbon is as follows: (1) Add 10g of activated carbon to 100mL of 1mol / L nitric acid solution, heat and stir at 80℃ for 2h, then filter, wash and dry to obtain pretreated activated carbon; (2) 10g of pretreated activated carbon was impregnated in 100mL of a mixed solution containing 5g of calcium chloride and 5g of magnesium nitrate, ultrasonically treated at 300W for 60min, then filtered, washed and dried, calcined at 550℃ for 2h, and ground through a 200-mesh sieve to obtain activated carbon composite material. (3) Place 10g of activated carbon composite material in 100mL of 3g / L hydrochloric acid dopamine solution, adjust the pH of the solution to 8.5, stir and react for 12h at room temperature and in the dark. After the reaction is completed, filter, wash and dry to obtain composite modified activated carbon.
[0033] S4. Operating cycle: 240 minutes / cycle, including water intake, aeration reaction, settling and drainage stages, with the settling time gradually shortened from 30 minutes to 3 minutes.
[0034] S5. Using sodium acetate as the carbon source, COD is approximately 800 mg / L, ammonia nitrogen is approximately 45 mg / L, TP is approximately 4 mg / L, and Ca... 2+ 10 mg / L, Mg 2+ The concentration is 10 mg / L.
[0035] S6. Systematically investigate the formation process and long-term operational stability of aerobic granular sludge.
[0036] When the entire operation cycle was 34 days, the concentration of ammonia nitrogen was detected to be 0.31 mg / L, which shows that the method provided in this embodiment has a good denitrification effect, and the proportion of aerobic granular sludge with a particle size >1 mm in the system is 93.9%.
[0037] Example 3 The application of a composite modified activated carbon in enhancing the rapid formation of aerobic granular sludge, the specific steps are as follows: S1. Set up a sequencing batch reactor (SBR) with an effective reactor volume of 2L.
[0038] S2, both reactors are filled with aerobic activated sludge MLSS=4500mg / L.
[0039] S3. Add 8g of composite modified activated carbon and 100mL of aerobic activated sludge to each 1L of effective reactor volume, adjust the pH to 7.5, and control the temperature at 25℃. The preparation method of the composite modified activated carbon is as follows: (1) Add 10g of activated carbon to 100mL of 1mol / L nitric acid solution, heat and stir at 80℃ for 2h, then filter, wash and dry to obtain pretreated activated carbon; (2) 15g of pretreated activated carbon was impregnated in 100mL of a mixed solution containing 6g of calcium chloride and 6g of magnesium nitrate, ultrasonically treated at 300W for 60min, then filtered, washed and dried, calcined at 550℃ for 2h, and ground through a 200-mesh sieve to obtain activated carbon composite material. (3) Place 10g of activated carbon composite material in 100mL of 2.5g / L hydrochloric acid dopamine solution, adjust the pH of the solution to 8.5, stir and react for 12h at room temperature and in the dark. After the reaction is completed, filter, wash and dry to obtain composite modified activated carbon.
[0040] S4. Operating cycle: 240 minutes / cycle, including water intake, aeration reaction, settling and drainage stages, with the settling time gradually shortened from 30 minutes to 3 minutes.
[0041] S5. Using sodium acetate as the carbon source, COD is approximately 800 mg / L, ammonia nitrogen is approximately 45 mg / L, TP is approximately 4 mg / L, and Ca...2+ 10 mg / L, Mg 2+ The concentration is 10 mg / L.
[0042] S6. Systematically investigate the formation process and long-term operational stability of aerobic granular sludge.
[0043] When the entire operation cycle was 34 days, the concentration of ammonia nitrogen was detected to be 0.18 mg / L, which shows that the method provided in this embodiment has a good denitrification effect, and the proportion of aerobic granular sludge with a particle size >1 mm in the system is 94.6%.
[0044] Comparative Example 1 The application of activated carbon in enhancing the rapid formation of aerobic granular sludge, the specific steps are as follows: S1. Set up a sequencing batch reactor (SBR) with an effective reactor volume of 2L.
[0045] S2, both reactors are filled with aerobic activated sludge MLSS=4500mg / L.
[0046] S3. Add 5g of activated carbon and 100mL of aerobic activated sludge to each 1L of effective reactor volume, adjust the pH to 7.5, and control the temperature at 25℃.
[0047] S4. Operating cycle: 240 minutes / cycle, including water intake, aeration reaction, settling and drainage stages, with the settling time gradually shortened from 30 minutes to 3 minutes.
[0048] S5. Using sodium acetate as the carbon source, COD is approximately 800 mg / L, ammonia nitrogen is approximately 45 mg / L, TP is approximately 4 mg / L, and Ca... 2+ 10 mg / L, Mg 2+ The concentration is 10 mg / L.
[0049] S6. Systematically investigate the formation process and long-term operational stability of aerobic granular sludge.
[0050] When the entire operation cycle was 34 days, the concentration of ammonia nitrogen was detected to be 3.53 mg / L, and the proportion of aerobic granular sludge with a particle size >1 mm in the system was 68.2%.
[0051] Compared with Example 1, no modification treatment was performed on the activated carbon in Comparative Example 1.
[0052] Comparative Example 2 The application of a modified activated carbon in enhancing the rapid formation of aerobic granular sludge, the specific steps are as follows: S1. Set up a sequencing batch reactor (SBR) with an effective reactor volume of 2L.
[0053] S2, both reactors are filled with aerobic activated sludge MLSS=4500mg / L.
[0054] S3. Add 5g of modified activated carbon and 100mL of aerobic activated sludge to each 1L of effective reactor volume, adjust the pH to 7.5, and control the temperature at 25℃. The modified activated carbon is prepared as follows: (1) Add 10g of activated carbon to 100mL of 1mol / L nitric acid solution, heat and stir at 80℃ for 2h, then filter, wash and dry to obtain pretreated activated carbon; (2) 10g of pretreated activated carbon was immersed in 100mL of a mixed solution containing 3g calcium chloride and 3g magnesium nitrate, ultrasonically treated at 300W for 60min, then filtered, washed and dried, calcined at 550℃ for 2h, and ground through a 200-mesh sieve to obtain modified activated carbon.
[0055] S4. Operating cycle: 240 minutes / cycle, including water intake, aeration reaction, settling and drainage stages, with the settling time gradually shortened from 30 minutes to 3 minutes.
[0056] S5. Using sodium acetate as the carbon source, COD is approximately 800 mg / L, ammonia nitrogen is approximately 45 mg / L, TP is approximately 4 mg / L, and Ca... 2+ 10 mg / L, Mg 2+ The concentration is 10 mg / L.
[0057] S6. Systematically investigate the formation process and long-term operational stability of aerobic granular sludge.
[0058] When the entire operation cycle was 34 days, the concentration of ammonia nitrogen was detected to be 1.86 mg / L, and the proportion of aerobic granular sludge with a particle size >1 mm in the system was 78.7%.
[0059] Compared to Example 1, the activated carbon composite material in Comparative Example 2 was not covered with a polydopamine film.
[0060] Comparative Example 3 The application of a modified activated carbon in enhancing the rapid formation of aerobic granular sludge, the specific steps are as follows: S1. Set up a sequencing batch reactor (SBR) with an effective reactor volume of 2L.
[0061] S2, both reactors are filled with aerobic activated sludge MLSS=4500mg / L.
[0062] S3. Add 5g of modified activated carbon and 100mL of aerobic activated sludge to each 1L of effective reactor volume, adjust the pH to 7.5, and control the temperature at 25℃. The modified activated carbon is prepared as follows: (1) Add 10g of activated carbon to 100mL of 1mol / L nitric acid solution, heat and stir at 80℃ for 2h, then filter, wash and dry to obtain pretreated activated carbon; (2) Place 5g of pretreated activated carbon in 100mL of 2g / L dopamine hydrochloride solution, adjust the pH of the solution to 8.5, stir and react for 12h at room temperature and in the dark. After the reaction is completed, filter, wash and dry to obtain modified activated carbon.
[0063] S4. Operating cycle: 240 minutes / cycle, including water intake, aeration reaction, settling and drainage stages, with the settling time gradually shortened from 30 minutes to 3 minutes.
[0064] S5. Using sodium acetate as the carbon source, COD is approximately 800 mg / L, ammonia nitrogen is approximately 45 mg / L, TP is approximately 4 mg / L, and Ca... 2+ 10 mg / L, Mg 2+ The concentration is 10 mg / L.
[0065] S6. Systematically investigate the formation process and long-term operational stability of aerobic granular sludge.
[0066] When the entire operation cycle was 34 days, the concentration of ammonia nitrogen was detected to be 1.17 mg / L, and the proportion of aerobic granular sludge with a particle size >1 mm in the system was 84.9%.
[0067] Compared to Example 1, Comparative Example 3 showed no metal oxide loading on the activated carbon.
[0068] Comparative Example 4 The application of a composite modified activated carbon in enhancing the rapid formation of aerobic granular sludge, the specific steps are as follows: S1. Set up a sequencing batch reactor (SBR) with an effective reactor volume of 2L.
[0069] S2, both reactors are filled with aerobic activated sludge MLSS=4500mg / L.
[0070] S3. Add 5g of composite modified activated carbon and 100mL of aerobic activated sludge to each 1L of effective reactor volume, adjust the pH to 7.5, and control the temperature at 25℃. The preparation method of the composite modified activated carbon is as follows: (1) Add 10g of activated carbon to 100mL of 1mol / L nitric acid solution, heat and stir at 80℃ for 2h, then filter, wash and dry to obtain pretreated activated carbon; (2) 10g of pretreated activated carbon was impregnated in 100mL of a solution containing 3g of calcium chloride, ultrasonically treated at 300W for 60min, then filtered, washed, dried, calcined at 550℃ for 2h, and ground through a 200-mesh sieve to obtain the activated carbon composite material. (3) Place 5g of activated carbon composite material in 100mL of 2g / L hydrochloric acid dopamine solution, adjust the pH of the solution to 8.5, stir and react for 12h at room temperature and in the dark. After the reaction is completed, filter, wash and dry to obtain composite modified activated carbon.
[0071] S4. Operating cycle: 240 minutes / cycle, including water intake, aeration reaction, settling and drainage stages, with the settling time gradually shortened from 30 minutes to 3 minutes.
[0072] S5. Using sodium acetate as the carbon source, COD is approximately 800 mg / L, ammonia nitrogen is approximately 45 mg / L, TP is approximately 4 mg / L, and Ca... 2+ 10 mg / L, Mg 2+ The concentration is 10 mg / L.
[0073] S6. Systematically investigate the formation process and long-term operational stability of aerobic granular sludge.
[0074] When the entire operation cycle was 34 days, the concentration of ammonia nitrogen was detected to be 0.96 mg / L, and the proportion of aerobic granular sludge with a particle size >1 mm in the system was 87.8%.
[0075] Compared to Example 1, Comparative Example 4 showed no magnesium oxide loading on the activated carbon.
[0076] Comparative Example 5 The application of a composite modified activated carbon in enhancing the rapid formation of aerobic granular sludge, the specific steps are as follows: S1. Set up a sequencing batch reactor (SBR) with an effective reactor volume of 2L.
[0077] S2, both reactors are filled with aerobic activated sludge MLSS=4500mg / L.
[0078] S3. Add 5g of composite modified activated carbon and 100mL of aerobic activated sludge to each 1L of effective reactor volume, adjust the pH to 7.5, and control the temperature at 25℃. The preparation method of the composite modified activated carbon is as follows: (1) Add 10g of activated carbon to 100mL of 1mol / L nitric acid solution, heat and stir at 80℃ for 2h, then filter, wash and dry to obtain pretreated activated carbon; (2) 10g of pretreated activated carbon was immersed in 100mL of solution containing 3g of magnesium nitrate, ultrasonically treated at 300W for 60min, then filtered, washed and dried, calcined at 550℃ for 2h, and ground through a 200-mesh sieve to obtain activated carbon composite material. (3) Place 5g of activated carbon composite material in 100mL of 2g / L hydrochloric acid dopamine solution, adjust the pH of the solution to 8.5, stir and react for 12h at room temperature and in the dark. After the reaction is completed, filter, wash and dry to obtain composite modified activated carbon.
[0079] S4. Operating cycle: 240 minutes / cycle, including water intake, aeration reaction, settling and drainage stages, with the settling time gradually shortened from 30 minutes to 3 minutes.
[0080] S5. Using sodium acetate as the carbon source, COD is approximately 800 mg / L, ammonia nitrogen is approximately 45 mg / L, TP is approximately 4 mg / L, and Ca... 2+ 10 mg / L, Mg 2+ The concentration is 10 mg / L.
[0081] S6. Systematically investigate the formation process and long-term operational stability of aerobic granular sludge.
[0082] When the entire operation cycle was 34 days, the concentration of ammonia nitrogen was detected to be 0.75 mg / L, and the proportion of aerobic granular sludge with a particle size >1 mm in the system was 89.1%.
[0083] Compared to Comparative Example 5 and Example 1, no calcium oxide was loaded on the activated carbon.
[0084] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.
Claims
1. The application of a composite modified activated carbon in enhancing the rapid formation of aerobic granular sludge, characterized in that, The preparation method of the composite modified activated carbon is as follows: S1. Add activated carbon to an acid solution, heat and stir, then filter, wash and dry to obtain pretreated activated carbon; S2. The pretreated activated carbon is impregnated in a mixed solution containing calcium chloride and magnesium nitrate, ultrasonically treated, and then filtered, washed, dried, calcined and ground to obtain the activated carbon composite material. S3. Place the activated carbon composite material in a hydrochloric acid dopamine solution, adjust the pH of the solution to 8-9, stir the reaction, and after the reaction is completed, filter, wash and dry to obtain the composite modified activated carbon.
2. The application according to claim 1, characterized in that, In step S1, the solid-liquid ratio of activated carbon to acid solution is 1g:10-20mL.
3. The application according to claim 1, characterized in that, In step S1, the heating and stirring temperature is 60-80℃, and the heating and stirring time is 2-4 hours.
4. The application according to claim 1, characterized in that, In step S2, the mass ratio of pretreated activated carbon, calcium chloride, and magnesium nitrate is 10-15:3-6:3-6.
5. The application according to claim 1, characterized in that, In step S2, the calcination temperature is 400-550℃ and the calcination time is 2-3 hours.
6. The application according to claim 1, characterized in that, In step S3, the ratio of activated carbon composite material to dopamine hydrochloride solution is 5-10g:100mL.
7. The application according to claim 1, characterized in that, In step S3, the concentration of the dopamine hydrochloride solution is 1-3 g / L.
8. The application according to claim 1, characterized in that, In step S3, the reaction is stirred for 12-24 hours at room temperature and in the dark.
9. The application according to claim 1, characterized in that, The ratio of composite modified activated carbon to aerobic granular sludge is 4-8g:100mL.