A low-temperature wastewater denitrification accelerator based on sodium acetate and its preparation method

Abstract

This invention belongs to the field of wastewater treatment technology, and discloses a low-temperature wastewater denitrification accelerator based on sodium acetate and its preparation method. The accelerator is composed of 85%–95% sodium acetate, 0.5%–5% N-dodecyl homoserine lactone, and 4.5%–10% hydroxylated mesoporous silica carrier, prepared by planetary ball milling. It utilizes a quorum sensing mechanism to activate eps gene expression, enhance EPS secretion, and improve carbon source adsorption and mass transfer efficiency. When applied, nitrate nitrogen removal rate can reach 94%, carbon source consumption is reduced by 18%–22%, sludge settling performance is significantly improved, and it is suitable for efficient denitrification of low-temperature wastewater at 8℃–15℃. This invention provides a low-temperature wastewater denitrification accelerator with a well-defined structure, clear mechanism of action, and strong engineering applicability, as well as its preparation method. This technical solution achieves a systematic improvement in the efficiency of low-temperature biological denitrification through precise molecular-level regulation and synergistic optimization of macroscopic processes.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology and relates to a low-temperature wastewater denitrification accelerator based on sodium acetate and its preparation method. Background Technology

[0002] In modern wastewater treatment systems, biological nitrogen removal is a core component in controlling eutrophication, and its efficiency directly impacts the stability of effluent quality and the sustainability of environmental carrying capacity. The denitrification process relies on heterotrophic denitrifying bacteria using organic carbon sources as electron donors under anaerobic conditions to reduce nitrates or nitrites to nitrogen gas, thus achieving effective nitrogen removal. Sodium acetate, due to its simple molecular structure, rapid biodegradation rate, and lack of secondary pollution risk, has long been widely used as an external carbon source, demonstrating excellent engineering applicability in municipal and industrial wastewater treatment. Especially in wastewater with low carbon-to-nitrogen ratios, supplementing with sodium acetate can significantly improve denitrification efficiency and has become a standard technical approach in the industry.

[0003] However, with the continuous expansion of wastewater treatment plant operating areas and the normalization of low-temperature conditions in winter, traditional sodium acetate dosing schemes face severe challenges in low-temperature environments. When the water temperature drops below 15°C, the physiological activity of denitrifying microorganisms is significantly suppressed, their cell membrane fluidity decreases, and enzymatic reaction rates slow down. More importantly, the low-temperature environment strongly inhibits the synthesis and secretion of extracellular polymers (EPS) by denitrifying bacteria. EPS, as a key medium for the stability of microbial aggregate structure and substrate mass transfer, not only provides a physical protective barrier for the microbial community but also plays a pivotal role in the adsorption, enrichment, and interfacial transfer of organic carbon sources. If the secretion of EPS by denitrifying bacteria is insufficient, even if the concentration of sodium acetate in the aqueous phase is sufficient, it is difficult to effectively capture and transport it to the cell surface, leading to a significant decrease in its bioavailability. This, in turn, triggers a chain reaction of problems such as sluggish denitrification rates, fluctuations in nitrogen removal efficiency, and even system collapse. Summary of the Invention

[0004] To achieve the above-mentioned objectives, this invention provides a sodium acetate-based low-temperature wastewater denitrification accelerator and its preparation method. The accelerator constructs a composite system with both efficient carbon source supply and low-temperature metabolic activation functions by combining sodium acetate with specific microbial signaling molecules. This aims to solve the problem of decreased sodium acetate bioavailability caused by insufficient extracellular polymeric substances (EPS) secretion by denitrifying bacteria under low-temperature conditions, thereby significantly improving the denitrification efficiency and system operational stability of low-temperature wastewater.

[0005] The low-temperature wastewater denitrification accelerator of this invention is composed of the following components by mass percentage: sodium acetate 85% to 95%, microbial signaling molecules 0.5% to 5%, and carrier material 4.5% to 10%. The microbial signaling molecules are N-acylhomoserine lactone compounds, specifically N-dodecylhomoserine lactone, with the molecular formula C0. 16 H 29 NO3, with a purity of not less than 98%, a melting point of 78℃ to 82℃, and a solubility in water of 120mg / L to 150mg / L.

[0006] The carrier material is mesoporous silica that has undergone surface hydroxylation treatment, and its specific surface area is 600 m². 2 / g to 800m 2 / g, pore size distribution of 2nm to 5nm, average particle size of 200nm to 500nm, surface hydroxyl density of 4.5OH / nm 2 6.0OH / nm 2 to.

[0007] The preparation method of the accelerator includes the following steps: First, the mesoporous silica carrier material is placed in deionized water to prepare a suspension with a mass concentration of 5%, and stirred at 300 rpm for 30 minutes under a 60°C water bath to ensure thorough dispersion of the carrier; then, an ethanol solution of N-dodecyl homoserine lactone is slowly added dropwise to the suspension, wherein the mass ratio of N-dodecyl homoserine lactone to the carrier material is 1:9 to 1:19, and the dropwise addition process lasts for 15 minutes. After the dropwise addition is completed, stirring is continued at 60°C for 2 hours. The signal molecules are loaded into the pores of the carrier through hydrogen bonds and van der Waals forces. Then, the loaded carrier material is filtered through a 0.22 μm microporous membrane, washed three times with anhydrous ethanol, and vacuum dried at 40 °C for 12 hours to obtain the loaded signal molecule carrier. Finally, the loaded signal molecule carrier is mixed with anhydrous sodium acetate powder in a certain proportion and co-milled in a planetary ball mill at 300 rpm for 60 minutes to make the carrier particles uniformly embedded in the interstices of sodium acetate crystals, thus obtaining the final low-temperature wastewater denitrification accelerator.

[0008] In a preferred embodiment of the present invention, the promoter comprises 90% sodium acetate, 2% N-dodecyl homoserine lactone, and 8% carrier material. Under this ratio, the promoter maximizes the increase in the secretion of extracellular polymers by denitrifying bacteria at a water temperature of 10°C. Laboratory tests show that the protein and polysaccharide content in the extracellular polymers of denitrifying bacteria is 2.3 times and 1.8 times higher, respectively, than that of the blank control group.

[0009] In another preferred embodiment of the present invention, the carrier material is modified with surface silanization to introduce carboxyl functional groups. Specifically, mesoporous silica is refluxed with 3-aminopropyltriethoxysilane in toluene solvent for 6 hours, and then reacted with succinic anhydride in N,N-dimethylformamide at 80°C for 4 hours, finally obtaining a surface carboxyl group density of 3.2COOH / nm. 2 The loading efficiency of N-dodecyl homoserine lactone was increased to 92%, an improvement of 18 percentage points compared to the unmodified carrier, and the sustained release rate of the signal molecule in the aqueous phase was controlled within 15% over 72 hours, ensuring its continuous and stable release in the reactor. This modified carrier... The mechanism of action of the promoter described in this invention is based on the principle of microbial quorum sensing (QS). When the promoter is added to a low-temperature anoxic reactor, sodium acetate rapidly dissolves in the aqueous phase, providing the electron donor required for denitrification; simultaneously, N-dodecyl homoserine lactone loaded in a mesoporous carrier is slowly released in the aqueous environment, diffuses to the surface of denitrifying bacteria cells, and specifically binds to LuxR-type receptor proteins on the cell membrane to form a signal-receptor complex.

[0010] The complex enters the cell nucleus and binds to the QS response element (QSRE) upstream of the EPS gene operon, initiating the transcription of genes encoding key enzymes for EPS synthesis, such as epsA, epsB, and epsC.

[0011] Furthermore, the increased secretion of EPS significantly improved the interfacial microenvironment of denitrifying bacteria aggregates. On the one hand, the EPS network structure enhanced the adsorption capacity of the bacterial micelles for soluble sodium acetate molecules, enriching acetate ions around the cells through electrostatic interactions and hydrogen bonding, thereby increasing the local carbon source concentration. On the other hand, the EPS hydrogel phase reduced substrate diffusion resistance, accelerating the rate of sodium acetate transport to the cell membrane. Microelectrode measurements showed that, at 10°C, the sodium acetate concentration gradient inside the bacterial micelles was reduced by 62% compared to the system without the additive, indicating a significant improvement in mass transfer efficiency.

[0012] In practical applications, the promoter described in this invention is continuously added to the front end of the anoxic tank via a metering pump. The addition concentration is 3.5 mg to 4.5 mg of promoter for every 1 mg of nitrate nitrogen removed. This addition scheme ensures that signaling molecules establish an effective concentration at the initial stage of denitrification, simultaneously activating metabolic pathways and carbon source utilization.

[0013] In the preparation method described in this invention, the planetary ball milling process parameters have a decisive influence on the performance of the accelerator. When the ball milling speed is below 200 rpm, the carrier particles cannot be uniformly dispersed in the sodium acetate matrix, resulting in uneven release of signal molecules; when the speed is above 400 rpm, the sodium acetate crystals are excessively broken, increasing the specific surface area and making them prone to moisture absorption and agglomeration during storage. After optimization, grinding at 300 rpm for 60 minutes yields a final product with a concentrated particle size distribution (D50=120μm), good flowability (angle of repose <35°), and a signal molecule encapsulation rate >95%.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The technical solution of this invention solves the shortcomings of existing technologies that rely solely on increasing the dosage of sodium acetate or external heating, resulting in high operating costs, large system fluctuations, and high risks of secondary pollution. By precisely embedding microbial signaling molecules into the carbon source system, a technological paradigm shift from passive supply to active activation is achieved. This promoter not only maintains the core function of sodium acetate as a highly efficient carbon source, but also directionally enhances the physiological adaptability of denitrifying bacteria at low temperatures through the QS regulation mechanism, fundamentally breaking through the bioavailability bottleneck caused by limited EPS secretion.

[0015] 2. After the EPS content of sludge is increased, the structure of the bacterial flocs becomes denser, the settling performance is improved, and the load on the secondary settling tank is reduced.

[0016] 3. The sustained-release design of signaling molecules avoids the impact of instantaneous high concentrations, ensuring the ecological balance of the microbial community and having no inhibitory or toxic effects. Detailed Implementation

[0017] This invention provides a sodium acetate-based low-temperature wastewater denitrification promoter and its preparation method, aiming to solve the problem of decreased sodium acetate bioavailability caused by insufficient extracellular polymer secretion by denitrifying bacteria under low-temperature conditions. This invention constructs a composite system with both efficient carbon source supply and low-temperature metabolic activation functions by compounding sodium acetate with specific microbial signaling molecules, thereby significantly improving the denitrification efficiency and system operational stability of low-temperature wastewater.

[0018] The technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples, so as to ensure that those skilled in the art can fully understand and implement the present invention.

[0019] Example 1: Components: Sodium acetate 90%, N-dodecyl homoserine lactone 2%, unmodified mesoporous silica (specific surface area 700 m²) 2 / g, pore size 3nm, average particle size 350nm) 8%; Preparation parameters: N-dodecyl homoserine lactone to mesoporous silica mass ratio 1:19, planetary ball mill speed 300 rpm, grinding time 60 minutes, grinding temperature controlled at 40℃, vacuum drying temperature 40℃, vacuum degree -0.095MPa; Application conditions: Test temperature 10℃, dosage is 4.0mg accelerator per 1mg nitrate nitrogen removed.

[0020] Example 2: Components: Sodium acetate 90%, N-dodecyl homoserine lactone 2%, modified mesoporous silica (modified with 3-aminopropyltriethoxysilane and succinic anhydride, carboxyl group density 3.2 COOH / nm) 2 8%;) Preparation parameters: N-dodecyl homoserine lactone to modified mesoporous silica mass ratio 1:19, planetary ball mill speed 300 rpm, grinding time 60 minutes, grinding temperature controlled at 42℃, vacuum drying temperature 40℃, vacuum degree -0.095MPa; Application conditions: Test temperature 10℃, dosage is 4.0mg accelerator per 1mg nitrate nitrogen removed.

[0021] Example 3: Components: Sodium acetate 85%, N-dodecyl homoserine lactone 5%, unmodified mesoporous silica (specific surface area 650 m²) 2 / g, pore size 2.5nm, average particle size 300nm) 10%; Preparation parameters: N-dodecyl homoserine lactone to mesoporous silica mass ratio 1:9, planetary ball mill speed 300 rpm, grinding time 60 minutes, grinding temperature controlled at 43℃, vacuum drying temperature 40℃, vacuum degree -0.095MPa; Application conditions: Test temperature 8℃, dosage is 4.5mg accelerator per 1mg nitrate nitrogen removed.

[0022] Example 4: Components: Sodium acetate 95%, N-dodecyl homoserine lactone 0.5%, unmodified mesoporous silica (specific surface area 750 m²) 2 / g, pore size 4nm, average particle size 400nm) 4.5%; Preparation parameters: N-dodecyl homoserine lactone to mesoporous silica mass ratio 1:17, planetary ball mill speed 300 rpm, grinding time 60 minutes, grinding temperature controlled at 38℃, vacuum drying temperature 40℃, vacuum degree -0.095MPa; Application conditions: Test temperature 12℃, dosage is 3.5mg accelerator per 1mg nitrate nitrogen removed.

[0023] Example 5: Components: Sodium acetate 88%, N-dodecyl homoserine lactone 3%, modified mesoporous silica (carboxyl group density 3.2 COOH / nm) 2 9%;) Preparation parameters: N-dodecyl homoserine lactone to modified mesoporous silica mass ratio 1:15, planetary ball mill speed 300 rpm, grinding time 60 minutes, grinding temperature controlled at 41℃, vacuum drying temperature 40℃, vacuum degree -0.095MPa; Application conditions: Test temperature 9℃, dosage is 3.8mg accelerator per 1mg nitrate nitrogen removed.

[0024] Example 6: Components: Sodium acetate 92%, N-dodecyl homoserine lactone 1.5%, unmodified mesoporous silica (specific surface area 680 m²) 2 / g, pore size 3.5nm, average particle size 320nm) 6.5%; Preparation parameters: N-dodecyl homoserine lactone to mesoporous silica mass ratio 1:18, planetary ball mill speed 300 rpm, grinding time 60 minutes, grinding temperature controlled at 39℃, vacuum drying temperature 40℃, vacuum degree -0.095MPa; Application conditions: Test temperature 11℃, dosage is 3.7mg accelerator per 1mg nitrate nitrogen removed.

[0025] Example 7: Components: Sodium acetate 86%, N-dodecyl homoserine lactone 4%, modified mesoporous silica (carboxyl density 3.2 COOH / nm) 2 10%;) Preparation parameters: N-dodecyl homoserine lactone to modified mesoporous silica mass ratio 1:10, planetary ball mill speed 300 rpm, grinding time 60 minutes, grinding temperature controlled at 44℃, vacuum drying temperature 40℃, vacuum degree -0.095MPa; Application conditions: Test temperature 15℃, dosage is 4.2mg accelerator per 1mg nitrate nitrogen removed.

[0026] Comparative Example 1: Component: 100% sodium acetate; Preparation parameters: No ball milling, no carrier loading step, anhydrous sodium acetate powder is used directly; Application conditions: Test temperature 10℃, dosage is the amount of sodium acetate added for every 1mg of nitrate nitrogen removed (consistent with the basic amount of carbon source in Example 1).

[0027] Comparative Example 2: Components: Sodium acetate 92%, unmodified mesoporous silica (same as Example 1) 8%; Preparation parameters: planetary ball mill speed 300 rpm, grinding time 60 minutes, grinding temperature controlled at 40℃, vacuum drying temperature 40℃, vacuum degree -0.095MPa; Application conditions: Test temperature 10℃, dosage is 4.0 mg per 1 mg nitrate nitrogen removed (consistent with the dosage in Example 1).

[0028] Comparative Example 3: Components: Sodium acetate 98%, N-dodecyl homoserine lactone 2%; Preparation parameters: The two powders are directly mixed without ball milling or carrier loading steps; Application conditions: Test temperature 10℃, dosage is 4.0 mg per 1 mg nitrate nitrogen removed (consistent with the dosage in Example 1).

[0029] Test method: Nitrate nitrogen removal rate determination: Ion chromatography was used. Wastewater samples before and after the reaction were filtered through a 0.45 μm filter membrane and the nitrate nitrogen concentration was detected by ion chromatography. The removal rate was calculated (removal rate = (influent nitrate nitrogen concentration - effluent nitrate nitrogen concentration) / influent nitrate nitrogen concentration × 100%).

[0030] Carbon source consumption reduction rate determination: The amount of sodium acetate required to remove one unit of nitrate nitrogen was calculated by detecting the concentration of acetate ions in the aqueous phase before and after the reaction (ion chromatography). The carbon source consumption reduction rate was obtained by comparing it with the pure sodium acetate group (Comparative Example 1). (Reduction rate = (consumption of pure sodium acetate group - consumption of experimental group) / consumption of pure sodium acetate group × 100%).

[0031] Sludge SVI value determination: According to the standard sludge settling performance test method, take mixed liquor sludge, let it stand for 30 minutes and record the settling volume. At the same time, measure the sludge concentration and calculate the SVI value (SVI = 30-minute settling volume / mL ÷ sludge concentration / g·L). -1 ).

[0032] Determination of protein and polysaccharide content in extracellular polymers: Proteins were stained using Coomassie Brilliant Blue G-250 staining, and polysaccharides were stained using the phenol-sulfuric acid method. The concentrations of protein and polysaccharides in extracellular polymers of the experimental group and the blank group (Comparative Example 1) were measured respectively, and the fold increase was calculated (fold increase = concentration of experimental group / concentration of blank group).

[0033] Determination of messenger ribonucleic acid expression of eps gene in denitrifying bacteria: Total ribonucleic acid was extracted from denitrifying bacteria using real-time quantitative polymerase chain reaction, and after reverse transcription into complementary deoxyribonucleic acid, the expression levels of messenger ribonucleic acid of epsA, epsB, and epsC genes were detected, and the fold increase was calculated by comparing with the blank group.

[0034] Determination of the effective diffusion coefficient of sodium acetate inside the fungal floc: The microelectrode method was used, in which a microelectrode was inserted into the fungal floc, and the change in sodium acetate concentration at different depths was monitored. The effective diffusion coefficient was calculated using Fick's law.

[0035] Signal molecule encapsulation rate determination: The concentration of N-dodecyl homoserine lactone in the carrier before and after loading was determined by high performance liquid chromatography, and the encapsulation rate was calculated (encapsulation rate = (mass of signal molecules in the carrier after loading / total mass of added signal molecules) × 100%).

[0036] Product Angle of Repose Measurement: The fixed funnel method is used to allow the accelerator powder to fall freely through the funnel, forming a conical accumulation. The angle of repose of the accumulation is measured (angle of repose = arctan(2h / d), where h is the height of the accumulation and d is the diameter of the bottom of the accumulation).

[0037] Performance test data comparison table 1:

[0038] Performance test data comparison table 2:

[0039] Comparing Examples 1-7 with Comparative Examples 1 (pure sodium acetate) and 2 (no signal molecule), it is evident that the examples with added N-dodecyl homoserine lactone achieved nitrate nitrogen removal rates of 92%-96%, significantly higher than the 68% of Comparative Example 1 and 75% of Comparative Example 2. Simultaneously, the fold increases in epsA gene expression (3.8-4.5 times), EPS protein, and polysaccharide (protein 2.1-2.7 times, polysaccharide 1.7-2.2 times) were significantly higher than those in the comparative examples (Comparative Example 1: both 1.0 times; Comparative Example 2: protein 1.2 times, polysaccharide 1.1 times, gene 1.3 times). This indicates that N-dodecyl homoserine lactone can activate the quorum sensing mechanism of denitrifying bacteria, upregulate eps gene expression, and promote extracellular polymer secretion, thereby addressing the problem of insufficient bioavailability of sodium acetate at low temperatures.

[0040] Comparing Example 1 and Comparative Example 3 (without carrier), the nitrate nitrogen removal rate of Example 1 (94%) is higher than that of Comparative Example 3 (82%), the carbon source consumption reduction rate (20%) is higher than that of Comparative Example 3 (8%), and the SVI value (95 mL / g) is lower than that of Comparative Example 3 (120 mL / g). Furthermore, both examples showed signal molecule encapsulation rates (73%-75% with unmodified carrier, 90%-92% with modified carrier), while Comparative Example 3 showed no encapsulation effect. This indicates that the carrier can achieve stable loading and sustained release of signal molecules, preventing rapid loss of signal molecules, prolonging their action time, and improving product flowability (angle of repose of Example 1: 30°-34°, compared to 42° in Comparative Example 3), thus enhancing the convenience of engineering applications.

[0041] Comparing Example 1 (unmodified carrier) with Example 2 (modified carrier) and Example 5 (modified carrier), it can be seen that the signal molecule encapsulation rate of the modified carrier group (90%-92%) is significantly higher than that of the unmodified carrier group (73%-75%), the nitrate nitrogen removal rate (95%-96%) is slightly higher than that of the unmodified group (92%-94%), and the EPS increase factor (protein 2.5-2.7 times, polysaccharide 2.0-2.2 times) is also higher than that of the unmodified group (protein 2.1-2.4 times, polysaccharide 1.7-1.9 times). This is because the carboxyl functional groups on the surface of the modified carrier can enhance the binding force with N-dodecyl homoserine lactone, improve the loading efficiency, and thus enhance the metabolic activation effect on denitrifying bacteria.

[0042] Example 3 (8℃, high signal molecules, high carrier) and Example 7 (15℃, high signal molecules, modified carrier) both achieved removal rates of over 92% in different low-temperature ranges, indicating that the promoter is applicable in the range of 8℃-15℃; Example 4 (low signal molecules, low carrier, 12℃) achieved a removal rate of 93%, indicating that even when the proportion of signal molecules and carrier is low, it can still meet the requirements for low-temperature denitrification, demonstrating the flexibility of the formulation.

[0043] The promoter of this invention solves the problems of low denitrification efficiency and carbon source waste of traditional pure sodium acetate at low temperatures through a synergistic system of sodium acetate carbon source supply + N-dodecyl homoserine lactone metabolism activation + carrier-loaded slow release. Compared with the prior art, the carbon source consumption of the embodiment is reduced by 18%-22%, the sludge SVI value is reduced to below 98 mL / g, the denitrification rate is significantly improved, and the preparation process is simple and the product has good stability, which can meet the low-temperature and high-efficiency denitrification requirements of wastewater treatment plants in cold regions.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a low-temperature wastewater denitrification accelerator based on sodium acetate, characterized in that, The accelerator is composed of the following components in mass percentage: Sodium acetate 85% to 95%, microbial signaling molecules 0.5% to 5%, carrier materials 4.5% to 10%; The microbial signal molecule is N-dodecanoylhomoserine lactone, with a melting point of 78°C to 82°C and a solubility in water of 120 mg / L to 150 mg / L. The carrier material is modified mesoporous silica with carboxyl functional groups introduced after surface silanization, and its surface carboxyl group density is 3.2 COOH / nm. 2 ; The modified mesoporous silica is prepared by the following steps: mesoporous silica is refluxed with 3-aminopropyltriethoxysilane in toluene for 6 hours, and then reacted with succinic anhydride in N,N-dimethylformamide at 80°C for 4 hours. The preparation method of the low-temperature wastewater denitrification accelerator includes the following steps: S10: Place the carrier material in deionized water to prepare a suspension with a mass concentration of 5%, and stir for 30 minutes in a 60°C water bath at 300 rpm. S20: Slowly add an ethanol solution of N-dodecyl homoserine lactone to the suspension over a period of 15 minutes. After the addition is complete, continue stirring at 60°C and 300 rpm for 2 hours to load the signal molecules into the carrier pores. S30: The loaded carrier was filtered through a 0.22 μm microporous membrane, washed three times with anhydrous ethanol, and dried under vacuum at 40 °C for 12 hours to obtain the loaded signal molecule carrier. S40: The loaded signal molecule carrier is mixed with anhydrous sodium acetate powder in a certain proportion, and then blended and ground in a planetary ball mill at 300 rpm for 60 minutes to obtain the final accelerator.

2. The preparation method according to claim 1, characterized in that, In step S20, the mass ratio of N-dodecyl homoserine lactone to mesoporous silica is 1:9 to 1:

19.

3. The preparation method according to claim 1, characterized in that, In step S20, the residual concentration of N-dodecyl homoserine lactone in the supernatant is monitored by high performance liquid chromatography, and the loading is determined to be balanced when the change in loading rate between two consecutive sampling intervals of 30 minutes is less than 0.5%.

4. The preparation method according to claim 1, characterized in that, In step S30, the vacuum degree during filtration is -0.085 MPa, and the temperature during vacuum drying is 40°C with a vacuum degree of -0.095 MPa. The water content of the resulting supported signal molecule carrier is less than 0.3%.

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