Slow-release composite functional filler for in-situ remediation of black and odorous water body and preparation method thereof

Abstract

This invention discloses a slow-release composite functional filler for in-situ remediation of black and odorous water bodies and its preparation method, belonging to the field of water environment treatment and ecological restoration technology. The slow-release composite functional filler includes citric acid-aminosilane synergistic confined modified biochar, sodium humate, zeolite powder, attapulgite, calcium nitrate, polyferric sulfate, polyhydroxybutyrate microspheres, sodium alginate, chitosan, and carnosine. The citric acid-aminosilane synergistic confined modified biochar is prepared by synergistic confined modification of biochar, citric acid, and γ-aminopropyltriethoxysilane. This invention improves the adsorption and fixation capacity of the material for ammonia nitrogen, phosphate, and organic pollutants by constructing a composite structure with the synergistic effect of citric acid-aminosilane synergistic confined modified biochar and carnosine slow-release system, enhancing the odor suppression effect and microbial activity, while simultaneously achieving a continuous slow-release supply of functional components. It is suitable for in-situ remediation of black and odorous water bodies in rivers, lakes, and landscape water bodies.

Description

Technical Field

[0001] This invention belongs to the field of water environment management and ecological restoration technology, specifically relating to a slow-release composite functional filler for in-situ remediation of black and odorous water bodies and its preparation method. Background Technology

[0002] Black and odorous water bodies refer to water bodies that are black or dark in color and accompanied by a strong odor, formed by the long-term accumulation of organic pollutants, nitrogen and phosphorus nutrients, and reducing substances, which decompose under anaerobic or hypoxic conditions. With the acceleration of urbanization and industrialization, a large amount of domestic sewage, industrial wastewater, and non-point source pollutants enter rivers, lakes, and landscape water bodies, leading to problems such as reduced dissolved oxygen, increased ammonia nitrogen and total phosphorus concentrations, and aggravated release of endogenous pollutants from bottom sediments in some water bodies, seriously affecting the aquatic ecological environment and the quality of life of residents.

[0003] Currently, the main methods for treating black and odorous water bodies include pollution interception and source control, dredging and sediment removal, aeration and oxygenation, microbial remediation, and in-situ remediation using filler materials. Among these, in-situ remediation technology has received widespread attention due to its simple construction, minimal disturbance to the water body, low operating costs, and ability to achieve long-term sustainable treatment. Existing in-situ remediation fillers typically use porous materials such as zeolite, biochar, and attapulgite as carriers to remove ammonia nitrogen, phosphate, and some organic pollutants through adsorption. However, existing fillers generally suffer from problems such as a limited number of active sites, insufficient pollutant adsorption capacity, rapid degradation of adsorption performance during long-term operation, and weak microbial attachment ability, making it difficult to meet the requirements for long-term stable remediation of black and odorous water bodies.

[0004] Furthermore, to promote denitrification and microbial growth, existing technologies typically add carbon sources such as glucose, sodium acetate, starch, or polylactic acid to the water. However, the release rate of these substances is difficult to control, easily leading to problems such as excessively rapid release in the early stages and insufficient carbon supply in the later stages. This not only reduces remediation efficiency but may also cause localized increases in organic load, triggering new risks of water quality deterioration. Simultaneously, traditional fillers have limited ability to inhibit the release of sulfides, volatile odorous substances, and endogenous phosphorus from sediment, making it difficult to achieve sustained elimination of black and odorous conditions.

[0005] Therefore, developing an in-situ remediation packing material that combines efficient adsorption, slow-release carbon supply, phosphorus removal and nitrogen fixation, odor suppression and microbial community reconstruction functions, and improving its long-term stable remediation capability in black and odorous water bodies, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To overcome the technical problems of existing in-situ remediation fillers for black and odorous water bodies, such as limited adsorption capacity, insufficient active sites, poor slow-release performance, insufficient carbon supply sustainability, weak microbial attachment ability, and unstable long-term remediation effects, this invention aims to provide a slow-release composite functional filler for in-situ remediation of black and odorous water bodies and its preparation method. The filler includes citric acid-aminosilane synergistic confined modified biochar, sodium humate, zeolite powder, attapulgite, calcium nitrate, polyferric sulfate, polyhydroxybutyrate microspheres, sodium alginate, chitosan, and carnosine. The citric acid-aminosilane synergistic confined modified biochar is obtained by synergistic confined modification of biochar with citric acid and γ-aminopropyltriethoxysilane. The polyhydroxybutyrate microspheres are internally loaded with carnosine and sodium humate to form a slow-release system, thereby constructing a composite remediation material with functions of pollutant adsorption and fixation, slow-release carbon supply, phosphorus and nitrogen removal, and microecological regulation. This invention significantly improves the removal capacity of packing material for ammonia nitrogen, phosphate and organic pollutants in black and odorous water bodies by constructing a composite structure that combines citric acid-aminosilane synergistic confined modified biochar and carnosine sustained-release system, and enhances the long-term stable remediation performance of the packing material.

[0007] The objective of this invention can be achieved through the following technical solutions: A slow-release composite functional filler for in-situ remediation of black and odorous water bodies comprises the following raw materials in parts by weight: 40-80 parts of citric acid-aminosilane synergistic confined modified biochar; 10-30 parts of sodium humate; 10-40 parts of zeolite powder; 5-25 parts of attapulgite; 3-15 parts of calcium nitrate; 2-12 parts of polyferric sulfate; 3-20 parts of polyhydroxybutyrate microspheres; 2-10 parts of sodium alginate; 1-8 parts of chitosan; and 0.1-3 parts of carnosine; wherein the citric acid-aminosilane synergistic... The confined modified biochar is prepared by synergistic confining modification of biochar, citric acid, and γ-aminopropyltriethoxysilane. The citric acid is fixed on the surface of the biochar to form a carboxyl-rich active layer, and the γ-aminopropyltriethoxysilane is hydrolyzed and condensed to form a silicon-oxygen network, which is combined with the surface of the biochar and the carboxyl-rich active layer, thereby constructing an organic-inorganic synergistic confined structure on the surface of the biochar. The polyhydroxybutyrate microspheres are loaded with carnosine and sodium humate to achieve the sustained release of functional components.

[0008] Optionally, the citric acid-aminosilane synergistic confinement modified biochar comprises the following raw materials in parts by weight: 100-200 parts biochar; 5-30 parts citric acid; 3-20 parts γ-aminopropyltriethoxysilane; 50-150 parts ethanol; and 80-250 parts deionized water.

[0009] Optionally, the preparation method of citric acid-aminosilane synergistic confinement modified biochar includes the following steps: (1) Citric acid and biochar were mixed to obtain citric acid pre-modified biochar; (2) Add γ-aminopropyltriethoxysilane to citric acid premodified biochar and react to obtain silicon-oxygen network modified biochar; (3) The silicon-oxygen network modified biochar was separated, washed and dried to obtain citric acid-aminosilane synergistic confinement modified biochar.

[0010] Optionally, the reaction conditions in step (1) are as follows: citric acid is added to a mixed solvent consisting of ethanol and deionized water, stirred and dissolved at 40-70°C, then biochar is added, and stirred at 300-800 rpm for 30-180 min.

[0011] Optionally, the reaction conditions for step (2) are to adjust the pH of the system to 8-10 and react at 50-80℃ for 2-8 hours.

[0012] Optionally, the reaction conditions for step (3) are washing with ethanol and deionized water until neutral, and drying at 60–100°C for 6–24 h.

[0013] Optionally, a method for preparing a fine-structured, highly stable fused alumina refractory material includes the following steps: S1, Sodium humate, carnosine and polyhydroxybutyrate are mixed to prepare polyhydroxybutyrate microspheres loaded with sodium humate and carnosine. S2, citric acid-aminosilane synergistic confinement modified biochar, zeolite powder, attapulgite, calcium nitrate, polyferric sulfate and polyhydroxybutyrate microspheres are mixed evenly to obtain a mixture; S3, sodium alginate and chitosan are added to the mixture for mixing and granulation, followed by solidification and drying to obtain a slow-release composite functional filler for in-situ remediation of black and odorous water bodies.

[0014] Optionally, the reaction conditions for step S1 are as follows: sodium humate and carnosine are added to a polyhydroxybutyrate solution, emulsified at 500–2000 rpm for 10–60 min, and then the solvent is evaporated and solidified at 30–80 °C to obtain polyhydroxybutyrate microspheres loaded with sodium humate and carnosine.

[0015] Optionally, the reaction conditions for step S2 are as follows: at 20-50°C, the citric acid-aminosilane synergistic confined modified biochar, zeolite powder, attapulgite, calcium nitrate, polyferric sulfate and polyhydroxybutyrate microspheres are stirred at 200-800 rpm for 20-120 min.

[0016] Optionally, the reaction conditions for step S3 are as follows: after adding sodium alginate and chitosan, stir for 10-60 min, granulate, solidify in a calcium chloride solution with a mass fraction of 1-5% for 10-120 min, and dry at 40-80℃ for 4-24 h to obtain a slow-release composite functional filler for in-situ remediation of black and odorous water bodies.

[0017] The beneficial effects of this invention are: This invention employs citric acid and γ-aminopropyltriethoxysilane for synergistic confinement modification of biochar. Citric acid constructs a carboxyl-rich active layer on the biochar surface, while γ-aminopropyltriethoxysilane forms a stable silicon-oxygen network structure, achieving a strong bond between the organic active layer and the biochar framework. Compared to ordinary biochar, the organic-inorganic synergistic confinement structure constructed in this invention significantly increases the number of active sites on the material surface, improves specific surface area and pore utilization, thereby enhancing the adsorption and fixation capacity for ammonia nitrogen, phosphate, and organic pollutants. Simultaneously, it improves the structural stability and durability of the packing material in complex aquatic environments.

[0018] This invention is the first to introduce carnosine into an in-situ remediation packing system for black and odorous water bodies, and utilizes polyhydroxybutyrate microspheres to synergistically load and slowly release carnosine and sodium humate. The imidazole groups in carnosine can interact with metal ions and reducing substances in the water, helping to reduce the generation of malodorous substances such as hydrogen sulfide. Simultaneously, during the slow release process, carnosine and sodium humate continuously improve the microbial growth environment, enhance the activity of functional bacterial communities, and promote ammonia nitrogen conversion and organic pollutant degradation, thus achieving a remediation effect superior to traditional single carbon supply systems.

[0019] This invention utilizes polyhydroxybutyrate microspheres to construct a long-lasting, slow-release carbon supply system, effectively addressing the problems of rapid release, short duration of action, and insufficient carbon supply in the later stages associated with traditional soluble carbon sources. The functional components can be continuously and stably released into the water, providing long-term carbon source support for microbial metabolism, improving the stability of the denitrification process, and reducing the increased costs and water disturbance caused by repeated additions during operation.

[0020] This invention organically combines citric acid-aminosilane synergistic confined modified biochar, carnosine slow-release system, zeolite powder, attapulgite, polyferric sulfate and sodium humate, so that the packing material has multiple functions such as pollutant adsorption and fixation, slow-release carbon supply, phosphorus removal and nitrogen fixation, odor suppression and micro-ecological reconstruction. It can achieve synergistic purification and ecological restoration of black and odorous water bodies, and significantly improve the in-situ remediation efficiency and long-term operational stability of black and odorous water bodies. Attached Figure Description

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] Figure 1A comparison chart showing the ammonia nitrogen removal rate test results for samples with different ratios. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0024] Example 1: The purpose of this example is to verify the in-situ remediation effect of the prepared slow-release composite functional filler on black and odorous water bodies when the components are used in the lower limit ratio and under lower reaction conditions.

[0025] S1, 5 parts of citric acid were added to a mixed solvent consisting of 50 parts of ethanol and 80 parts of deionized water and stirred at 40°C to dissolve. Then, 100 parts of biochar were added and stirred at 300 rpm for 30 min. Next, 3 parts of γ-aminopropyltriethoxysilane were added to adjust the pH of the system to 8 and reacted at 50°C for 2 h. After the reaction was completed, the mixture was washed with ethanol and deionized water until neutral and dried at 60°C for 6 h to obtain citric acid-aminosilane synergistic confinement modified biochar. S2, 10 parts of sodium humate and 0.1 parts of carnosine were added to 3 parts of polyhydroxybutyrate solution, emulsified at 500 rpm for 10 min, and then the solvent was evaporated and solidified at 30 °C to obtain polyhydroxybutyrate microspheres loaded with sodium humate and carnosine; then 40 parts of citric acid-aminosilane synergistic confined modified biochar, 10 parts of zeolite powder, 5 parts of attapulgite, 3 parts of calcium nitrate, 2 parts of polyferric sulfate and the polyhydroxybutyrate microspheres were stirred at 200 rpm for 20 min at 20 °C to obtain a mixture; S3. Add 2 parts sodium alginate and 1 part chitosan to the mixture obtained in step S2, stir for 10 min and then granulate; place the obtained particles in a 1% calcium chloride solution to solidify for 10 min and dry at 40℃ for 4 h to obtain a slow-release composite functional filler for in-situ remediation of black and odorous water bodies.

[0026] Example 2: The purpose of this example is to verify the synergistic effect of citric acid-aminosilane co-confined modified biochar and carnosine sustained-release system when the components are in the median ratio and under moderate reaction conditions.

[0027] S1, 17.5 parts of citric acid were added to a mixed solvent consisting of 100 parts of ethanol and 165 parts of deionized water and stirred at 55°C to dissolve. Then, 150 parts of biochar were added and stirred at 550 rpm for 105 min. Then, 11.5 parts of γ-aminopropyltriethoxysilane were added to adjust the pH of the system to 9 and reacted at 65°C for 5 h. After the reaction was completed, the mixture was washed with ethanol and deionized water until neutral and dried at 80°C for 15 h to obtain citric acid-aminosilane synergistic confinement modified biochar. S2, 20 parts of sodium humate and 1.5 parts of carnosine were added to 11.5 parts of polyhydroxybutyrate solution and emulsified at 1250 rpm for 35 min. Then, the solvent was evaporated and solidified at 55 °C to obtain polyhydroxybutyrate microspheres loaded with sodium humate and carnosine. Then, 60 parts of citric acid-aminosilane synergistic confined modified biochar, 25 parts of zeolite powder, 15 parts of attapulgite, 9 parts of calcium nitrate, 7 parts of polyferric sulfate and the polyhydroxybutyrate microspheres were stirred at 500 rpm for 70 min at 35 °C to obtain a mixture. S3. Add 6 parts sodium alginate and 4.5 parts chitosan to the mixture obtained in step S2, stir for 35 min and then granulate; place the obtained particles in a 3% calcium chloride solution to solidify for 65 min and dry at 60℃ for 14 h to obtain a slow-release composite functional filler for in-situ remediation of black and odorous water bodies.

[0028] Example 3: The purpose of this example is to verify the long-term repair performance and structural stability of the slow-release composite functional filler when the components are used at the upper limit ratio and under higher reaction conditions.

[0029] S1, 30 parts of citric acid were added to a mixed solvent consisting of 150 parts of ethanol and 250 parts of deionized water and stirred at 70°C to dissolve. Then, 200 parts of biochar were added and stirred at 800 rpm for 180 min. Next, 20 parts of γ-aminopropyltriethoxysilane were added to adjust the pH of the system to 10 and reacted at 80°C for 8 h. After the reaction was completed, the mixture was washed with ethanol and deionized water until neutral and dried at 100°C for 24 h to obtain citric acid-aminosilane synergistic confinement modified biochar. S2, 30 parts of sodium humate and 3 parts of carnosine were added to 20 parts of polyhydroxybutyrate solution and emulsified at 2000 rpm for 60 min. Then, the solvent was evaporated and solidified at 80 °C to obtain polyhydroxybutyrate microspheres loaded with sodium humate and carnosine. Then, 80 parts of citric acid-aminosilane synergistic confined modified biochar, 40 parts of zeolite powder, 25 parts of attapulgite, 15 parts of calcium nitrate, 12 parts of polyferric sulfate and the polyhydroxybutyrate microspheres were stirred at 800 rpm for 120 min at 50 °C to obtain a mixture. S3. Add 10 parts sodium alginate and 8 parts chitosan to the mixture obtained in step S2, stir for 60 min and then granulate; place the obtained particles in a 5% calcium chloride solution to solidify for 120 min and dry at 80℃ for 24 h to obtain a slow-release composite functional filler for in-situ remediation of black and odorous water bodies.

[0030] Comparative Example 1: The purpose of this comparative example is to verify the effect of citric acid-modified biochar on the repair performance of slow-release composite functional fillers after replacing citric acid-aminosilane synergistic confined modified biochar.

[0031] S1, 17.5 parts of citric acid were added to a mixed solvent consisting of 100 parts of ethanol and 165 parts of deionized water and stirred at 55°C to dissolve. Then 150 parts of biochar were added and stirred at 550 rpm for 105 min. After the reaction was completed, the mixture was washed with ethanol and deionized water until neutral and dried at 80°C for 15 h to obtain citric acid modified biochar. S2, 20 parts of sodium humate and 1.5 parts of carnosine were added to 11.5 parts of polyhydroxybutyrate solution and emulsified at 1250 rpm for 35 min. Then, the solvent was evaporated and solidified at 55 °C to obtain polyhydroxybutyrate microspheres loaded with sodium humate and carnosine. Then, 60 parts of citric acid modified biochar, 25 parts of zeolite powder, 15 parts of attapulgite, 9 parts of calcium nitrate, 7 parts of polyferric sulfate and the polyhydroxybutyrate microspheres were stirred at 500 rpm for 70 min at 35 °C to obtain a mixture. S3. Add 6 parts sodium alginate and 4.5 parts chitosan to the mixture obtained in step S2, stir for 35 min and then granulate; place the obtained particles in a 3% calcium chloride solution to solidify for 65 min and dry at 60℃ for 14 h to obtain a slow-release composite functional filler for in-situ remediation of black and odorous water bodies.

[0032] Comparative Example 2: The purpose of this comparative example is to verify the effect of aminosilane-modified biochar on the repair performance of slow-release composite functional fillers after replacing citric acid-aminosilane synergistic confined modified biochar.

[0033] S1, 150 parts of biochar were added to a mixed solvent consisting of 100 parts of ethanol and 165 parts of deionized water, followed by the addition of 11.5 parts of γ-aminopropyltriethoxysilane. The pH of the system was adjusted to 9, and the reaction was carried out at 65°C for 5 h. After the reaction was completed, the biochar was washed with ethanol and deionized water until neutral, and then dried at 80°C for 15 h to obtain aminosilane-modified biochar. S2, 20 parts of sodium humate and 1.5 parts of carnosine were added to 11.5 parts of polyhydroxybutyrate solution and emulsified at 1250 rpm for 35 min. Then, the solvent was evaporated and solidified at 55 °C to obtain polyhydroxybutyrate microspheres loaded with sodium humate and carnosine. Then, 60 parts of aminosilane modified biochar, 25 parts of zeolite powder, 15 parts of attapulgite, 9 parts of calcium nitrate, 7 parts of polyferric sulfate and the polyhydroxybutyrate microspheres were stirred at 500 rpm for 70 min at 35 °C to obtain a mixture. S3. Add 6 parts sodium alginate and 4.5 parts chitosan to the mixture obtained in step S2, stir for 35 min and then granulate; place the obtained particles in a 3% calcium chloride solution to solidify for 65 min and dry at 60℃ for 14 h to obtain a slow-release composite functional filler for in-situ remediation of black and odorous water bodies.

[0034] Comparative Example 3: The purpose of this comparative example is to verify the effect of carnosine on the repair performance of sustained-release composite functional fillers.

[0035] S1, 17.5 parts of citric acid were added to a mixed solvent consisting of 100 parts of ethanol and 165 parts of deionized water and stirred at 55°C to dissolve. Then, 150 parts of biochar were added and stirred at 550 rpm for 105 min. Then, 11.5 parts of γ-aminopropyltriethoxysilane were added to adjust the pH of the system to 9 and reacted at 65°C for 5 h. After the reaction was completed, the mixture was washed with ethanol and deionized water until neutral and dried at 80°C for 15 h to obtain citric acid-aminosilane synergistic confinement modified biochar. S2, 20 parts of sodium humate were added to 11.5 parts of polyhydroxybutyrate solution, emulsified at 1250 rpm for 35 min, and then the solvent was evaporated and solidified at 55 °C to obtain polyhydroxybutyrate microspheres loaded with sodium humate; then 60 parts of citric acid-aminosilane synergistic confined modified biochar, 25 parts of zeolite powder, 15 parts of attapulgite, 9 parts of calcium nitrate, 7 parts of polyferric sulfate and the polyhydroxybutyrate microspheres were stirred at 500 rpm for 70 min at 35 °C to obtain a mixture; S3. Add 6 parts sodium alginate and 4.5 parts chitosan to the mixture obtained in step S2, stir for 35 min and then granulate; place the obtained particles in a 3% calcium chloride solution to solidify for 65 min and dry at 60℃ for 14 h to obtain a slow-release composite functional filler for in-situ remediation of black and odorous water bodies.

[0036] Performance testing: 1. Ammonia nitrogen removal rate test Two L of simulated black and odorous water was taken, with an initial ammonia nitrogen concentration controlled at 20 mg / L. The same mass of the slow-release composite functional packing material obtained in the examples and comparative examples was added to each. The samples were continuously aerated and cultured at 25℃ for 14 days, with samples taken every 2 days. The ammonia nitrogen concentration in the water samples was determined using Nessler's reagent spectrophotometry, and the ammonia nitrogen removal rate was calculated based on the changes in ammonia nitrogen concentration before and after treatment to evaluate the packing material's ability to remove ammonia nitrogen pollutants from black and odorous water.

[0037] 2. Total phosphorus removal rate test Two L of simulated black and odorous water was taken, with an initial total phosphorus concentration controlled at 5 mg / L. The same mass of the slow-release composite functional packing material obtained in the examples and comparative examples was added, and the mixture was incubated at 25℃ for 14 days. The total phosphorus concentration in the water before and after treatment was determined by ammonium molybdate spectrophotometry, and the total phosphorus removal rate was calculated to evaluate the packing material's effect on phosphorus pollutant fixation and removal.

[0038] 3. Hydrogen sulfide inhibition rate test A simulated black and odorous water body system containing bottom sediment was used. The slow-release composite functional packing materials obtained in the examples and comparative examples were added to the system and anaerobically cultured at 25℃ for 21 days. The concentration of hydrogen sulfide generated at the interface between the water and bottom sediment during the culture process was determined by methylene blue spectrophotometry, and the hydrogen sulfide inhibition rate was calculated using the blank group as a reference to evaluate the packing material's ability to inhibit the formation of malodorous substances in black and odorous water bodies.

[0039] 4. Continuous stability testing and repair Five liters of simulated black and odorous water were taken, and the same mass of the slow-release composite functional packing materials obtained in the examples and comparative examples were added. The mixture was continuously operated at 25°C for 60 days, and the ammonia nitrogen removal rate was measured every 10 days. The ratio of the ammonia nitrogen removal rate on day 60 to that on day 10 was used as the remediation stability retention rate to evaluate the slow-release carbon supply capacity and long-term continuous remediation performance of the packing material.

[0040] Table 1. Performance test results of the examples and comparative examples.

[0041] According to Table 1 and Figure 1 The slow-release composite functional packing materials obtained from different embodiments and comparative examples showed significant differences in ammonia nitrogen removal rate, total phosphorus removal rate, hydrogen sulfide inhibition rate, and remediation stability retention rate. Among them, Example 2 achieved the highest performance levels in all indicators, with an ammonia nitrogen removal rate of 95.8%, a total phosphorus removal rate of 94.3%, a hydrogen sulfide inhibition rate of 92.7%, and a remediation stability retention rate of 95.6%. This indicates that under moderate component ratios and moderate reaction conditions, the functional components can form an optimal synergistic effect, thereby achieving excellent remediation results for black and odorous water bodies.

[0042] Both Examples 1 and 3 achieved good test results, but their overall performance was slightly lower than that of Example 2. Specifically, Example 1, due to the lower component addition amount and reaction intensity, resulted in a relatively insufficient degree of citric acid-aminosilane synergistic confined structure construction, which limited the number of active sites on the material surface and the sustained carbon supply capacity of the controlled-release system. Therefore, its performance indicators were lower than those of Example 2. Although Example 3 increased the addition amount of each component and the reaction intensity, the excessive degree of modification may have led to the covering of some active sites. Furthermore, the higher component loading was not conducive to the full utilization of the pore structure; therefore, its performance was also slightly lower than that of Example 2.

[0043] Comparative Example 1 used citric acid-modified biochar instead of citric acid-aminosilane synergistic confinement modified biochar. The ammonia nitrogen removal rate, total phosphorus removal rate, hydrogen sulfide inhibition rate, and remediation stability retention rate decreased to 73.5%, 71.2%, 65.4%, and 72.8%, respectively. The results indicate that while citric acid modification alone can increase some surface-active groups, the lack of a silicon-oxygen network for stabilizing confinement of the active layer leads to a significant decrease in the material's long-term stability and pollutant adsorption capacity. This demonstrates that the synergistic confinement structure plays a crucial role in improving remediation performance.

[0044] Comparative Example 2, using aminosilane-modified biochar, showed slightly better performance than Comparative Example 1, but was still significantly lower than Example 2. This indicates that while the silicon-oxygen network formed by introducing aminosilane alone can improve the structural stability of the material, the lack of a carboxyl-rich active layer provided by citric acid limits the number of adsorption sites on the material surface, making it difficult to fully exert the synergistic removal effect on ammonia nitrogen, phosphate, and organic pollutants. This further demonstrates the necessity of synergistic modification with citric acid and aminosilane.

[0045] Comparative Example 3, which only removed carnosine, saw its ammonia nitrogen removal rate and total phosphorus removal rate decrease to 84.8% and 83.2%, respectively, its hydrogen sulfide inhibition rate decrease to 74.1%, and its remediation stability retention rate decrease to 81.7%. This indicates that carnosine in the system of this invention can not only participate in the odor inhibition process but also form a synergistic effect with the sodium humate slow-release system, providing a more suitable growth environment for functional microorganisms, thereby improving denitrification efficiency and long-term remediation capacity. The significant improvement in hydrogen sulfide inhibition rate, in particular, fully demonstrates the unexpected technical effects brought about by the introduction of carnosine.

[0046] In summary, this invention, by constructing a citric acid-aminosilane synergistic confined modified biochar and carnosine sustained-release system, achieves synergistic enhancement of functions such as pollutant adsorption and fixation, continuous carbon supply, odor suppression, and promotion of microecological restoration. Among these, Example 2 exhibits the best performance across all indicators, demonstrating that moderate component ratios and moderate reaction conditions can fully leverage the synergistic effect of each functional component, resulting in a sustained-release composite functional filler with excellent in-situ remediation performance and long-term operational stability for black and odorous water bodies.

Claims

1. A slow-release composite functional filler for in-situ remediation of black and odorous water, characterized in that, The raw materials include the following parts by weight: 40-80 parts of citric acid-aminosilane synergistic confinement modified biochar; 10-30 parts of sodium humate; 10-40 parts of zeolite powder; 5-25 parts of attapulgite; 3-15 parts of calcium nitrate; 2-12 parts of polyferric sulfate; 3-20 parts of polyhydroxybutyrate microspheres; 2-10 parts of sodium alginate; 1-8 parts of chitosan; and 0.1-3 parts of carnosine; wherein the citric acid-aminosilane synergistic confinement modified biochar is produced by biological... The biochar microspheres were prepared by synergistic confinement modification of char, citric acid, and γ-aminopropyltriethoxysilane. The citric acid was immobilized on the surface of the biochar to form a carboxyl-rich active layer. The γ-aminopropyltriethoxysilane was hydrolyzed and condensed to form a silicon-oxygen network, which was then combined with the surface of the biochar and the carboxyl-rich active layer, thereby constructing an organic-inorganic synergistic confinement structure on the surface of the biochar. The polyhydroxybutyrate microspheres were loaded with carnosine and sodium humate to achieve the sustained release of functional components.

2. The slow-release composite functional filler for in-situ remediation of black and odorous water bodies according to claim 1, characterized in that, The citric acid-aminosilane synergistic confinement modified biochar comprises the following raw materials in parts by weight: 100-200 parts biochar; 5-30 parts citric acid; 3-20 parts γ-aminopropyltriethoxysilane; 50-150 parts ethanol; and 80-250 parts deionized water.

3. A slow-release composite functional filler for in-situ remediation of black and odorous water bodies according to claim 1 or 2, characterized in that, The preparation method of the citric acid-aminosilane synergistic confinement modified biochar includes the following steps: (1) Citric acid and biochar were mixed to obtain citric acid pre-modified biochar; (2) Add γ-aminopropyltriethoxysilane to citric acid premodified biochar and react to obtain silicon-oxygen network modified biochar; (3) The silicon-oxygen network modified biochar was separated, washed and dried to obtain citric acid-aminosilane synergistic confinement modified biochar.

4. The slow-release composite functional filler for in-situ remediation of black and odorous water bodies according to claim 3, characterized in that, The reaction conditions for step (1) are as follows: citric acid is added to a mixed solvent consisting of ethanol and deionized water, stirred and dissolved at 40-70°C, then biochar is added, and stirred at 300-800 rpm for 30-180 min.

5. A slow-release composite functional filler for in-situ remediation of black and odorous water bodies according to claim 3, characterized in that, The reaction conditions for step (2) are to adjust the pH of the system to 8-10 and react at 50-80℃ for 2-8 hours.

6. The slow-release composite functional filler for in-situ remediation of black and odorous water bodies according to claim 3, characterized in that, The reaction conditions for step (3) are washing with ethanol and deionized water until neutral, and drying at 60-100°C for 6-24 hours.

7. A method for preparing a fine-structured, highly stable fused cast corundum refractory material, characterized in that, The preparation method includes the following steps: S1, Sodium humate, carnosine and polyhydroxybutyrate are mixed to prepare polyhydroxybutyrate microspheres loaded with sodium humate and carnosine. S2, citric acid-aminosilane synergistic confinement modified biochar, zeolite powder, attapulgite, calcium nitrate, polyferric sulfate and polyhydroxybutyrate microspheres are mixed evenly to obtain a mixture; S3, sodium alginate and chitosan are added to the mixture for mixing and granulation, followed by solidification and drying to obtain a slow-release composite functional filler for in-situ remediation of black and odorous water bodies.

8. The method for preparing a slow-release composite functional filler for in-situ remediation of black and odorous water bodies according to claim 7, characterized in that, The reaction conditions for step S1 are as follows: sodium humate and carnosine are added to a polyhydroxybutyrate solution, emulsified at 500-2000 rpm for 10-60 min, and then the solvent is evaporated and solidified at 30-80°C to obtain polyhydroxybutyrate microspheres loaded with sodium humate and carnosine.

9. The method for preparing a slow-release composite functional filler for in-situ remediation of black and odorous water bodies according to claim 7, characterized in that, The reaction conditions for step S2 are as follows: at 20-50°C, citric acid-aminosilane synergistic confined modified biochar, zeolite powder, attapulgite, calcium nitrate, polyferric sulfate and polyhydroxybutyrate microspheres are stirred at 200-800 rpm for 20-120 min.

10. The method for preparing a slow-release composite functional filler for in-situ remediation of black and odorous water bodies according to claim 7, characterized in that, The reaction conditions for step S3 are as follows: after adding sodium alginate and chitosan, stir for 10-60 min, granulate, solidify in a calcium chloride solution with a mass fraction of 1-5% for 10-120 min, and dry at 40-80℃ for 4-24 h to obtain a slow-release composite functional filler for in-situ remediation of black and odorous water bodies.

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