Preparation method of sediment micro-ecological reconstruction and pollutant targeted fixation conditioning agent

Abstract

This application relates to the field of water pollution control technology and discloses a method for preparing a sediment microecological reconstruction and pollutant-targeted immobilization conditioner. The method includes: modifying mesoporous silica with amino- and thiolated compounds and mixing it with biochar to obtain an adsorbent material; dispersing ferrous sulfate, sodium thiosulfate, and hydroxyapatite with the adsorbent material in a sodium alginate solution and adding it dropwise to a calcium chloride solution for cross-linking and chitosan coating to obtain microcapsules; compounding riboflavin, humic acid, carbon source nutrients, and adding signaling molecules to obtain a metabolic enhancer; compounding metalloenzyme inhibitors and activating them with microorganisms to obtain an activator; granulating and coating calcium carbonate, magnesium hydroxide, ferrous sulfate, sulfur powder, calcium peroxide, and sodium lactate to obtain buffer particles; mixing the adsorbent material, microcapsules, and buffer particles, spraying, adding the metabolic enhancer and activator, adding binders and pore-forming agents, granulating, drying, sieving, and spraying a protective film to obtain the conditioner. This application solves the technical problems of existing sediment conditioners, such as single function, uncontrolled release, and microecological imbalance.

Description

Technical Field

[0001] This application relates to the field of water pollution control technology, and in particular to a method for preparing a sediment microecological reconstruction and pollutant targeted fixation conditioner. Background Technology

[0002] Sediment pollution control is a key step in water environment restoration. Existing sediment conditioning agents mainly include two categories: chemical passivators and bioremediation agents. Chemical passivators, such as lime and phosphate, fix heavy metals by precipitation or adsorption, while bioremediation agents promote the degradation of organic matter by adding exogenous microorganisms or nutrients. Some products use a simple physical mixing method to combine adsorbent materials with passivators, achieving pollutant control through a one-time addition.

[0003] However, existing technologies have significant shortcomings: single-function conditioners only target a certain type of pollutant in heavy metals or organic matter, and their effect on the remediation of sediments with complex pollution is limited; the release of each component in simple physical mixing compound products is uncontrollable, and rapid dissolution can lead to excessively high local concentrations, causing toxicity or premature consumption, resulting in weak remediation in the later stages; the addition of exogenous microorganisms has problems such as competition with native microbial communities, poor adaptability, and difficulty in colonization, and it ignores the microbial potential of the sediment itself; traditional powder or granular conditioners have low mechanical strength, are easily broken and lost under the scouring of water flow, and have poor resistance to disturbance. Summary of the Invention

[0004] This application provides a method for preparing a sediment microecological reconstruction and pollutant-targeted immobilization conditioner. It is used to achieve multi-level capture and immobilization of pollutants by constructing gradient pore size adsorption materials, to achieve on-demand release of functional components by using an intelligent responsive double-layer coating structure, and to achieve autonomous microecological repair by enhancing anaerobic metabolism and enzymatic activation of indigenous microbial communities through electron shuttles. This method solves the technical problems of existing sediment conditioners, such as single function, uncontrolled release, and microecological imbalance.

[0005] This application provides a method for preparing a sediment microecological reconstruction and pollutant-targeted immobilization conditioner, the method comprising: Step S1: After sequentially modifying the mesoporous silica support with amination and thiolization, it is mixed with oxidized biochar to obtain a gradient pore size composite adsorbent material. Step S2: Ferrous sulfate, sodium thiosulfate and hydroxyapatite precursor are mixed and then dispersed together with the gradient pore size composite adsorbent in sodium alginate solution and added dropwise to calcium chloride solution for cross-linking. Then, the mixture is coated with chitosan to obtain a double-layer sustained-release passivated microcapsule. Step S3: After combining riboflavin, humic acid, carbon source and nutrients, add signaling molecules to obtain anaerobic metabolism enhancer concentrate. Step S4: After combining the metal salt activator, enzyme preparation and inhibitor, the mixture is activated by the indigenous microbial concentrate to obtain the indigenous microbial community targeted activator; Step S5: A pH buffer is prepared by mixing calcium carbonate-magnesium hydroxide with ferrous sulfate-sulfur powder, and an Eh regulator is prepared by mixing calcium peroxide with sodium lactate. The two are then compounded and granulated to obtain pH-Eh synergistic buffer particles. Step S6: Mix the gradient pore size composite adsorbent material, the double-layer slow-release passivation microcapsules and the pH-Eh synergistic buffer particles, spray in the anaerobic metabolism enhancer concentrate and the indigenous microbial community directional activator, add the composite binder and pore-forming agent, granulate by extrusion, dry and sieve, and then spray with a biological protective film to obtain the conditioner.

[0006] The technical solution provided in this application prepares a gradient pore size composite adsorbent material by sequentially modifying a mesoporous silica support through amylation and thiolization, and then mixing it with oxidized biochar. A synergistic system of thiol-amino-carboxyl triple functional groups is constructed on the material surface. Thiol groups achieve a triple fixation mechanism for heavy metal ions through coordination bonds, amino groups through electrostatic attraction, and carboxyl groups through ion exchange and surface complexation. Simultaneously, the gradient pore size structure includes a macroporous layer that traps suspended particles and large organic molecules, a mesoporous layer that selectively adsorbs heavy metal ions, and a microporous layer that deeply captures small molecule pollutants. A three-dimensional capture network of physical sieving, chemical bonding, and electrostatic attraction was formed, effectively solving the problems of low capacity, poor selectivity, and easy desorption of traditional single-functional group adsorbents. By mixing ferrous sulfate, sodium thiosulfate, and hydroxyapatite precursors with gradient pore size composite adsorbents and using sodium alginate-chitosan bilayer coating technology to prepare slow-release passivation microcapsules, the pH-responsive characteristics of the calcium alginate inner layer and the Eh-responsive characteristics of the chitosan outer layer were utilized to achieve intelligent on-demand release of the passivating agent and adsorbent material according to changes in sediment environmental parameters. In an acidic environment, cross-linking weakens and releases more rapidly to neutralize acidity. The outer layer of chitosan undergoes chain breakage in an anaerobic, low-potential environment, increasing porosity and promoting diffusion. This effectively solves the problems of excessively high local concentrations or premature consumption caused by traditional single-dose additions, significantly improving the utilization rate of functional components and extending their effective duration. An anaerobic metabolism enhancer concentrate was prepared by using riboflavin and humic acid as electron shuttles, combined with carbon sources and nutrients, and adding signaling molecules. Riboflavin and humic acid lower the electron transfer activation energy between methanogens and iron-reducing bacteria, while signaling molecules activate gene expression in indigenous bacterial communities. Upregulating key metabolic enzymes effectively solves the problems of poor adaptability and colonization difficulties of traditional exogenous bacterial agents, and fully realizes the potential of indigenous microorganisms. By combining metal salt activators, enzyme preparations and inhibitors and activating them with concentrated indigenous microbial solution to prepare targeted activators, nickel ions activate urease, manganese and cobalt ions activate phosphatase, exogenous enzymes pre-degrade macromolecular organic matter, and inhibitors control the excessive growth of sulfate-reducing bacteria, a three-dimensional activation mechanism of enzyme activation-substrate supply-microbial community regulation is formed, which effectively solves the problems of low activity and insufficient expression of functional genes in indigenous microorganisms.

[0007] By using calcium carbonate-magnesium hydroxide and ferrous sulfate-sulfur powder as anti-acidification and anti-alkaliification buffers respectively, and calcium peroxide and sodium lactate as oxygen source and electron donor respectively, pH-Eh synergistic buffer particles were prepared. Calcium carbonate rapidly neutralizes acidity while magnesium hydroxide provides long-lasting buffering. Calcium peroxide slowly releases oxygen to create a micro-aerobic environment on the surface while sodium lactate provides electrons to maintain an anaerobic environment in the deeper layers. This achieves bidirectional pH stabilization and stratified Eh regulation, ensuring that the sediment meets the aerobic requirements of nitrifying bacteria on the surface and the anaerobic requirements of methanogenic bacteria in the deeper layers. This effectively solves the problem of drastic fluctuations in environmental parameters that inhibit microbial activity caused by traditional conditioners. Furthermore, by mixing gradient pore size composite adsorption materials, double-layer slow-release passivated microcapsules, and pH-Eh synergistic buffer particles at a dry basis mass ratio, and then spraying with a concentrated anaerobic metabolism enhancer and a native microbial community targeted activator, and then adding... The mixture incorporates bentonite-sodium carboxymethyl cellulose-molasses composite binder and ammonium bicarbonate pore-forming agent. After extrusion granulation, drying, and sieving, it is coated with a sodium alginate-chitosan bio-protective film. This process achieves uniform dispersion, stable coating, and synergistic effects of the multifunctional components. Bentonite absorbs water and swells to form a gel network that encapsulates each component. Sodium carboxymethyl cellulose crosslinks to form a three-dimensional network that enhances strength. Molasses, after drying, forms a glassy structure that improves adhesion. Ammonium bicarbonate decomposes to create pores, increasing specific surface area and permeation channels. The bio-protective film prevents breakage during transportation and slows down rapid dissolution. This effectively solves the problems of component stratification, low strength, easy pulverization, and uncontrolled release in traditional simple mixed products. Ultimately, it achieves a dual-effect synergy of targeted pollutant fixation and microecological reconstruction, enabling the sediment conditioner to exhibit significant advantages in the treatment of complex pollution, including comprehensive functions, controllable release, high remediation efficiency, and long-lasting effects. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic diagram of an embodiment of the preparation method of sediment microecological reconstruction and pollutant targeted fixation conditioner in this application. Detailed Implementation

[0010] This application provides a method for preparing a sediment microecological reconstruction and pollutant-targeted fixation conditioner. The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms "comprising" or "having" and any variations thereof are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0011] For ease of understanding, the specific process of the embodiments of this application is described below. Please refer to [link / reference]. Figure 1 One embodiment of the preparation method of the sediment microecological reconstruction and pollutant targeted immobilization conditioner in this application includes: Step S1: After sequentially modifying the mesoporous silica support with amination and thiolization, it is mixed with oxidized biochar to obtain a gradient pore size composite adsorbent material. Step S2: Ferrous sulfate, sodium thiosulfate and hydroxyapatite precursor are mixed and then dispersed together with gradient pore size composite adsorbent in sodium alginate solution and added dropwise to calcium chloride solution for cross-linking. Then, the mixture is coated with chitosan to obtain a double-layer sustained-release passivated microcapsule. Step S3: After combining riboflavin, humic acid, carbon source and nutrients, add signaling molecules to obtain anaerobic metabolism enhancer concentrate. Step S4: After combining the metal salt activator, enzyme preparation and inhibitor, the mixture is activated by the indigenous microbial concentrate to obtain the indigenous microbial community targeted activator; Step S5: A pH buffer is prepared by mixing calcium carbonate-magnesium hydroxide with ferrous sulfate-sulfur powder, and an Eh regulator is prepared by mixing calcium peroxide with sodium lactate. The two are then compounded and granulated to obtain pH-Eh synergistic buffer particles. Step S6: Mix gradient pore size composite adsorbent material, double-layer slow-release passivation microcapsules and pH-Eh synergistic buffer particles, spray with anaerobic metabolism enhancer concentrate and indigenous microbial community directional activator, add composite binder and pore-forming agent, granulate by extrusion, dry and sieve, and then spray with a biological protective film to obtain conditioner.

[0012] It is understood that the executing entity of this application can be a sediment microecological reconstruction and pollutant targeted immobilization conditioner preparation system, or it can be a terminal or a server; the specific implementation is not limited here. This application's embodiments use a server as an example for illustration.

[0013] Specifically, the amination modification involves a condensation reaction between the silane coupling agent KH-550 and the silanol groups on the surface of mesoporous silica, forming Si-O-Si covalent bonds and introducing amino functional groups onto the material surface. The reaction mechanism is that the silane coupling agent is hydrolyzed in ethanol solvent to generate silanol groups, which then undergo dehydration condensation with the hydroxyl groups on the silica surface. The reflux reaction temperature is controlled at 75 to 85 degrees Celsius for 4 to 6 hours to ensure the reaction proceeds fully. After removing unreacted reagents by filtration, a modified material with uniformly distributed amino groups on the surface is obtained. Thiolization modification is based on the formation of amide bonds between amino and carboxyl groups. The amino-modified material is dispersed in an aqueous solution, and 3-mercaptopropionic acid is added dropwise as a thiol source. Simultaneously, EDC and NHS are added as condensing agents to activate the carboxyl groups. EDC first reacts with the carboxyl groups of thiolpropionic acid to form the active intermediate O-acylisourea. NHS further reacts with this intermediate to generate a stable NHS active ester. This active ester then undergoes a nucleophilic substitution reaction with the amino groups on the material surface to form stable amide bonds, thus successfully grafting thiol groups onto the material surface. The reaction pH is controlled between 5.5 and 6.5 because at this pH range, the carboxyl groups are in a partially deprotonated state, which is conducive to activation, while the amino groups are in a partially protonated state, maintaining a certain degree of nucleophilicity. The reaction temperature is maintained at 25 to 35 degrees Celsius to avoid hydrolysis and deactivation of the condensing agents. The reaction time is 8 to 10 hours to ensure that the thiol grafting rate reaches saturation. Carboxylation of biochar is achieved through nitric acid oxidation. Bamboo charcoal or straw charcoal, after being carbonized at 700 to 800 degrees Celsius under oxygen-limited conditions, has a rich aromatic carbon skeleton and surface defect sites. Nitric acid, as a strong oxidant, oxidizes carbon atoms on the surface of biochar to carboxyl groups under reflux conditions at 80 to 90 degrees Celsius. The oxidation reaction involves the electrophilic attack of the nitric acid group on carbon and the subsequent hydrolysis process. The reflux time of 4 to 6 hours makes the carboxyl content reach 2.0 to 3.2 mmol / g. When thiol-amino bifunctional materials are mixed with carboxylated biochar at a mass ratio of 3:2, the thiol groups are mainly immobilized by forming coordinate bonds with heavy metal ions. In the coordinate bonds, the lone pair electrons of the sulfur atom form σ bonds with the empty orbitals of the metal ions. For cadmium ions, the bond energy of the cadmium-sulfur bond is about 208 kJ / mol, which is much higher than that of electrostatic adsorption. In the solution, the amino group is protonated into a positively charged ammonium ion, which attracts the negatively charged heavy metal anion complex through electrostatic interaction or forms a coordinate bond with the metal ion through the lone pair electrons of the nitrogen atom. The carboxyl group is adsorbed through the coordination of the carboxyl oxygen atom with the metal ion and the ion exchange between the carboxylate ion and the metal ion. The synergistic effect of the three functional groups greatly improves the adsorption capacity compared with materials with single functional groups.

[0014] The mixing of ferrous sulfate and sodium thiosulfate in a molar ratio of 2:1 is based on the metabolic characteristics of sulfate-reducing bacteria under anaerobic conditions. Under anaerobic conditions, sulfate-reducing bacteria use sulfate ions as electron acceptors for respiration, reducing sulfate ions to sulfide ions. The chemical reaction is: sulfate ion adds 8 electrons and 9 hydrogen ions to generate sulfhydryl ions and 4 water molecules. Sodium thiosulfate, as an intermediate oxidized sulfur source, is more easily utilized by microorganisms. Ferrous ions can participate in the metabolism of iron-reducing bacteria as electron donors and can also react in situ with sulfide ions produced by microorganisms to generate ferrous sulfide precipitate. Ferrous sulfide is further converted into more stable iron sulfides such as pyrrhotite. These iron sulfides have a synergistic fixation effect on heavy metals. On the one hand, they embed heavy metal ions into the crystal lattice through isomorphous substitution. On the other hand, the negatively charged surface of the iron sulfides captures cationic heavy metals through electrostatic attraction. Hydroxyapatite precursors are prepared by co-precipitation of calcium chloride and diammonium hydrogen phosphate at a calcium-to-phosphorus molar ratio of 5:3. Calcium ions and phosphate ions react under alkaline conditions to generate hydroxyapatite crystal nuclei, which are then calcined at 500 to 600 degrees Celsius for 2 to 4 hours to perfect the crystal structure. The chemical formula of hydroxyapatite is pentacalcium triphosphate hydroxyl. Calcium ions in its crystal lattice can undergo isomorphous substitution with lead or cadmium ions to form stable metal phosphate minerals. These minerals have extremely low solubility product constants. For example, the solubility product constant of pentacalcium triphosphate hydroxyl is approximately 10 to ... The passivating agent mixture and the gradient pore size composite adsorbent were mixed at a mass ratio of 1.5:1 and then dispersed in a sodium alginate solution. Sodium alginate is a linear polysaccharide composed of mannuronic acid and guluronic acid. The carboxyl groups on the molecular chain are deprotonated under neutral to weakly alkaline conditions to form negatively charged carboxylate ions. When the sodium alginate suspension containing the passivating agent and adsorbent is dropped into a calcium chloride solution, the calcium ions rapidly undergo ionic cross-linking with the carboxylate ions on the sodium alginate molecular chain. Each calcium ion can simultaneously bind two carboxylate ions to form a cross-linked network similar to an egg-box structure. The droplet becomes spherical under the action of surface tension. After cross-linking and curing, spherical calcium alginate microcapsules are formed. The microcapsules encapsulate the passivating agent and adsorbent. The cross-linking reaction begins from the surface and propagates inward the moment the droplet contacts the calcium solution. The dropping height is controlled at 8 to 12 cm to ensure that the droplet has appropriate kinetic energy to penetrate the liquid surface without breaking. The curing time is 20 to 30 minutes to ensure that the microcapsules are fully cross-linked.Chitosan coating is based on polyelectrolyte composite action. Chitosan is a deacetylated product of chitin. Under acidic conditions, the amino groups on the molecular chain are protonated to form positively charged ammonium ions. When calcium alginate microcapsules are immersed in a chitosan solution, the positive charge on the chitosan molecular chain and the negatively charged carboxylate ions remaining on the microcapsule surface are electrostatically attracted to form a polyelectrolyte composite film. Chitosan molecular chains are deposited layer by layer on the microcapsule surface. An immersion time of 30 to 50 minutes results in a film thickness of 40 to 80 micrometers. This composite film is responsive to redox potential and can withstand anaerobic low-potential environments. The glycosidic bonds and amino groups on the lower chitosan molecular chain undergo reducing chain scission, increasing membrane porosity and promoting the outward diffusion of core substances. However, under aerobic high-potential conditions, the membrane structure remains compact, and the release rate decreases. This intelligent response characteristic is achieved through the potential-substance concentration relationship described by the Nernst equation, where the potential equals the standard electrode potential plus the gas constant multiplied by the absolute temperature divided by the electron transfer number multiplied by the Faraday constant, then multiplied by the concentration of the oxidized state divided by the natural logarithm of the concentration of the reduced state. By controlling the ambient potential, the permeability of the membrane is regulated, thereby achieving the on-demand release of the passivating agent.

[0015] The mechanism of action of riboflavin as an extracellular electron shuttle is based on its redox potential characteristics. The isochloroazine ring system in the riboflavin molecule can reversibly accept or release electrons. The standard potential of the reduced riboflavin dinucleotide is -0.22 volts. This potential value is between -0.30 to -0.40 volts at the end of the electron transport chain of methanogens and +0.77 volts for the reduction of iron ions in iron-reducing bacteria. According to the free energy change formula, the free energy change equals the number of negative electrons transferred multiplied by the Faraday constant multiplied by the potential difference. The larger the potential difference, the more negative the free energy change of the reaction, and the more easily the reaction proceeds spontaneously. After accepting electrons released by methanogens, riboflavin is transformed into a reduced state and then transfers electrons to iron ions or sulfate ions, significantly reducing the electron transport activation energy and accelerating the methanogenesis process. The quinone group structure in the humic acid molecule also has electron shuttle function. The quinone group can reversibly switch between the quinone and hydroquinone forms, with a standard potential range of -0.15 to -0.30 volts. It forms a complementary potential gradient with riboflavin, further promoting the transfer of electrons between different microbial populations. The design of the ratio of sodium acetate and glucose as carbon sources is based on the phased theory of anaerobic digestion. Glucose is first fermented by acid-producing bacteria into volatile fatty acids such as acetate, propionate, and butyrate. This process follows the glycolysis pathway and part of the tricarboxylic acid cycle. Theoretically, one molecule of glucose can produce two molecules of acetic acid. Acetic acid is the direct substrate of methanogens. The reaction formula for the conversion of acetate to methane is that acetate ions generate methane and carbon dioxide. The free energy change of this reaction is -31 kJ / mol methane. It is an exothermic reaction, but the energy release is relatively small, requiring methanogens to finely regulate metabolism. In the initial stage, a high concentration of glucose (800 to 1000 mg / L) and sodium acetate (1600 to 2000 mg / L) is added to quickly initiate the hydrolysis, acidification, and acetic acid production stages. In the later stage, the concentration is reduced to glucose (50 to 80 mg / L) and sodium acetate (100 to 150 mg / L) to maintain stable methanogenesis without causing the accumulation of volatile fatty acids, which would lead to a decrease in pH and inhibit methanogens. The nutrient ratio was designed based on a carbon-nitrogen-phosphorus mass ratio of 100:5:1, taking into account the elemental composition of microbial cells. Ammonium chloride provided the nitrogen source, potassium dihydrogen phosphate provided the phosphorus source and potassium ions, and among the trace elements, nickel ions were the active metal center for urease and carbon monoxide dehydrogenase, cobalt ions were a core element for vitamin B12, and molybdenum was a cofactor for formate dehydrogenase. These enzymes all participate in key steps of anaerobic metabolism. The signaling molecule N-3-hydroxy-dodecyl-homoserine lactone belongs to the quorum sensing signaling class of acylhomoserine lactones. When the concentration reaches 10 to 50 nanomoles per liter, it can bind to LuxR-type transcriptional regulatory proteins of Gram-negative bacteria. This complex binds to the promoter region of specific genes, activating transcription and upregulating the expression of genes encoding denitrifying enzymes such as nitrate reductase and nitrite reductase, and methanogenic enzymes such as methyl-CoM reductase, thus simultaneously increasing the biomass and enzyme activity of the functional bacterial community.

[0016] The mechanism by which nickel sulfate acts as a urease activator is based on the fact that nickel ions are an essential component of the urease's double nickel active center. Urease catalyzes the hydrolysis of urea, in which urea adds water to produce two molecules of ammonia and carbon dioxide. The Michaelis constant of this reaction reflects the enzyme's affinity for the substrate; the smaller the Michaelis constant, the higher the enzyme's affinity for the substrate. In the presence of nickel ions, the Michaelis constant decreases from 15 to 20 mmol / L to 1.2 to 2.5 mmol / L. The catalytic efficiency is defined as the maximum reaction rate divided by the Michaelis constant. Nickel ions increase the catalytic efficiency by 8 to 12 times. Manganese sulfate and cobalt chloride were used as phosphatase activators because manganese and cobalt ions are metal cofactors for alkaline and acidic phosphatases, respectively. Phosphatases catalyze the hydrolysis of organophosphate compounds into inorganic phosphates. The reaction is: organic phosphate esters add water to produce alcohols and then add hydrogen phosphate. Using the Lineweaver-Burk double reciprocal plot method, a straight line was obtained by plotting the reciprocal of the reaction rate on the ordinate and the reciprocal of the substrate concentration on the abscissa. The slope of the line is the Michaelis constant divided by the maximum reaction rate, and the ordinate intercept is the reciprocal of the maximum reaction rate. After adding manganese and cobalt ions, the maximum reaction rate increased from 0.8 to 1.2 μmol / min / mg enzyme to 3.5 to 4.8 μmol / min / mg enzyme, an increase of about 3.5 times. The cellulase complex includes an endoglucanase that randomly cleaves the glycosidic bonds within the cellulose molecule, an exoglucanase that sequentially hydrolyzes the cellulose chain from the ends to produce cellobiose, and a β-glucosidase that hydrolyzes cellobiose into glucose. These three enzymes work synergistically to complete cellulose degradation. A protease hydrolyzes proteins into peptides and amino acids. These enzyme preparations convert recalcitrant macromolecular organic matter in the sediment into smaller molecules that can be utilized by microorganisms. The cellulase-catalyzed hydrolysis reaction follows the Michaelis-Menten equation, and the reaction rate is equal to the maximum reaction rate multiplied by the substrate concentration divided by the Michaelis constant plus the substrate concentration. By adding exogenous enzymes, the substrate conversion rate can be increased from 0.05 to 0.08 g / L / day to 0.35 to 0.50 g / L / day, accelerating the release of carbon sources. Metronidazole and sodium molybdate are used as a combination of inhibitors to control the overgrowth of sulfate-reducing bacteria. Metronidazole is reduced to an active metabolite under anaerobic conditions, selectively inhibiting the energy metabolism of sulfate-reducing bacteria and blocking the pathway of sulfate reduction to hydrogen sulfide. Sodium molybdate, as a structural analog of sulfate, competitively inhibits sulfate reductase, a key enzyme in the sulfate reduction process. Molybdate is structurally similar to sulfate but cannot be reduced, occupying the enzyme's active site and preventing sulfate binding. The inhibitor concentration is controlled within a range that inhibits sulfate-reducing bacteria but has little effect on methanogens and denitrifying bacteria. The half-inhibitory concentration is 0.5 to 1.0 mg / L for sulfate-reducing bacteria and greater than 20 mg / L for methanogens. After mixing the various stock solutions by volume, a surfactant such as Tween-80 is added. The surfactant molecules consist of hydrophilic head groups and hydrophobic tail chains, which form micelles in the solution to reduce surface tension, decreasing it from 72 millinewtons per meter to 35 to 40 millinewtons per meter and reducing the wetting angle from 110 degrees to 45 to 55 degrees, thereby improving the penetration and dispersion of the activator in the sediment.During anaerobic activation with the indigenous microbial concentrate, the concentrate was obtained by enriching and culturing sediment samples collected on-site. The enrichment culture was conducted under anaerobic conditions with sediment as inoculum and appropriate nutrients added to screen functional microbial communities adapted to the local environment. The activation process was carried out under anaerobic conditions at 25 to 30 degrees Celsius for 12 to 24 hours. The enzyme preparations and metal ions in the activator activated the metabolic enzyme system of the indigenous microorganisms, and the microorganisms began to grow, reproduce, and secrete extracellular enzymes. After activation, the dehydrogenase activity was determined by the triphenyltetrazole chloride method. Triphenyltetrazole was reduced to red triphenylformazan under the action of dehydrogenase. The concentration of triphenylformazan was quantitatively determined by colorimetric method to calculate the dehydrogenase activity. After activation, the dehydrogenase activity increased from 0.1 to 0.15 mg / g / hour to 0.5 to 0.8 mg / g / hour, an increase of 4 to 6 times.

[0017] The role of calcium carbonate and magnesium hydroxide as anti-acidification buffers is based on the reaction of alkaline substances with acids. The reaction formula of calcium carbonate with acid is calcium carbonate plus two hydrogen ions to generate calcium ions plus water plus carbon dioxide. The reaction rate is fast and can quickly neutralize the volatile fatty acids produced by the anaerobic degradation of bottom sediment. The solubility product constant of magnesium hydroxide is 5.6 x 10^-12, and its solubility is lower than that of calcium carbonate, providing a long-lasting buffering capacity. The reaction formula of magnesium hydroxide plus two hydrogen ions to generate magnesium ions plus two water molecules. The two are combined in a mass ratio of 3:1 to achieve a combination of rapid response and long-lasting buffering. Ferrous sulfate and sulfur powder are used as anti-alkali buffers based on the generation of acidic substances. In sediment, ammonia is produced through ammonification, leading to an increase in pH. The ammonification reaction involves nitrogenous organic matter adding water to form ammonia plus organic residues. Ferrous ions are oxidized under slightly aerobic conditions to produce hydrogen ions. The reaction is: four ferrous ions plus oxygen and ten water molecules to form four ferric hydroxide precipitates plus eight hydrogen ions. Sulfur powder is oxidized by sulfur-oxidizing bacteria to produce sulfuric acid. The reaction is: two elemental sulfur molecules plus three oxygen molecules and two water molecules to form two sulfuric acid molecules, releasing a large number of hydrogen ions and lowering the pH. According to the Henderson-Hasselbalch equation, pH equals the negative logarithm of the acid dissociation constant plus the base concentration divided by the logarithm of the acid concentration. Buffer capacity is defined as the reciprocal of the pH change caused by adding one mole of hydrogen or hydroxide ions. Buffer capacity equals 2.303 multiplied by the total buffer concentration multiplied by the acid dissociation constant multiplied by the hydrogen ion concentration divided by the square of the acid dissociation constant plus the hydrogen ion concentration. This buffer system reaches its maximum buffer capacity in the pH range of 6.0 to 7.5. Calcium peroxide slowly hydrolyzes in water, releasing oxygen. The reaction is two calcium peroxide molecules plus two water molecules to produce two calcium hydroxide molecules plus oxygen. The release rate is controlled by particle size and coating thickness. The oxygen release creates a micro-aerobic environment with dissolved oxygen of 0.2 to 0.5 mg / L in the 0 to 5 cm layer of bottom sediment. According to the Nernst equation, the potential is equal to the standard electrode potential plus the gas constant multiplied by the absolute temperature divided by the number of electrons transferred multiplied by the Faraday constant multiplied by the concentration of oxidized state divided by the natural logarithm of the concentration of reduced state. By controlling the oxygen release rate, the potential is maintained between +50 and +150 mV. This potential range meets the aerobic requirements of nitrifying bacteria. The nitrification reaction is ammonium ions plus two oxygen molecules to produce nitrate ions plus two hydrogen ions plus water. This also avoids complete aerobic conditions that would lead to the inactivation of methanogenic bacteria. Sodium lactate is oxidized under anaerobic conditions as an electron donor. The reaction is as follows: lactate ions add water to form acetate ions, bicarbonate ions, four hydrogen ions, and four electrons. The released electrons are used for sulfate reduction and iron reduction. The sulfate reduction reaction is as follows: sulfate ions add eight electrons and nine hydrogen ions to form sulfhydryl ions and four water molecules, with a standard potential of -0.22 volts. The iron reduction reaction is as follows: ferric ions add one electron to form ferrous ions. The potential for the reduction of ferric hydroxide to ferrous ions is approximately -0.10 volts, maintaining the potential of the deep sediment layer at -150 to -100 millivolts.A mixture of pH buffer and Eh regulator is compounded and then added to an aqueous solution of polyvinyl alcohol as a binder. Hydroxyl groups on the polyvinyl alcohol molecular chain form hydrogen bonds with the surface of the buffer particles. During mixing in a twin-screw extruder, the materials are thoroughly and uniformly mixed under the shear force of the screws. The extrusion temperature of 60-80 degrees Celsius causes partial dissolution of the polyvinyl alcohol, forming a viscous matrix. An extrusion pressure of 2-4 MPa forces the material through the die to form strips. During hot air drying, water evaporates and the polyvinyl alcohol solidifies, forming the particle skeleton. Ethyl cellulose coating is achieved through fluidized bed spraying. Ethyl cellulose dissolves in ethanol to form a coating solution. The particles are suspended in a fluidized state by an upward airflow in the fluidized bed. The coating solution is sprayed onto the particle surface through atomizing nozzles. Ethanol evaporates rapidly, leaving an ethyl cellulose film. The coating thickness is controlled to be 30-60 micrometers by spraying time and rate. The ethyl cellulose film slowly dissolves in water, controlling the release rate of the core material. The coated particles are then post-cured at 50-60 degrees Celsius for 2-3 hours. Post-curing relaxes the internal stress of the coating film, increases its density, and enhances its strength.

[0018] The gradient pore size composite adsorbent material, a bilayer slow-release passivated microcapsule, and pH-Eh synergistic buffer particles were mixed at a dry basis mass ratio of 2:3:2. This ratio was based on the functional positioning of each component. The adsorbent material (28.6% by mass) was responsible for the rapid capture of pollutants, the passivated microcapsule (42.8% by mass) provided long-term support for heavy metal fixation and organic matter degradation, and the buffer particles (28.6% by mass) maintained the stability of the microecological environment. The three were mixed in a high-speed mixer at a speed of 30 to 50 revolutions per minute for 30 to 50 minutes. The mixing uniformity was determined by measuring the content of each component at 10 random sampling points and calculating the coefficient of variation. The coefficient of variation was equal to the standard deviation divided by the mean multiplied by 100%. A coefficient of variation of less than 5% indicated that the mixing was uniform. When adding anaerobic metabolism enhancer concentrate and indigenous microbial community targeted activator by spraying, the spray pressure is 0.2 to 0.4 MPa to atomize the liquid into droplets with a diameter of less than 50 micrometers. The droplets are evenly distributed on the surface of the solid particles and penetrate into the internal pores of the particles through capillary action and surface adsorption. The total amount of liquid components added is 8% to 12% of the mass of the solid mixture. Bentonite, as an inorganic binder, absorbs water and expands 15 to 20 times to form a gel network. The expansion mechanism is the hydration of exchangeable cations between bentonite crystal layers. Water molecules enter the interlayer space, increasing the interlayer spacing. The resulting gel network encapsulates the particles of each component. The carboxyl groups on the sodium carboxymethyl cellulose molecular chain crosslink with calcium or magnesium ions to form a three-dimensional network structure. The crosslinking reaction involves two carboxyl groups forming a coordinate bond with a divalent metal ion. The polysaccharides in molasses dehydrate and concentrate during drying to form a glassy structure. Glassy sugars have high mechanical strength and binding force. Ammonium bicarbonate, as a pore-forming agent, decomposes during drying. The reaction is ammonium bicarbonate generating ammonia, water vapor, and carbon dioxide. These three gases form channels inside the particles with a pore size of 5 to 20 micrometers and a porosity of 20% to 30%. The increased channels enhance the specific surface area and water contact area, promoting full contact between the functional components and the sediment. The moisture content of the material is controlled between 18% and 25%. The moisture content is measured within 3 minutes using a rapid moisture analyzer with a drying method at 105 degrees Celsius. The moisture content is calculated as wet weight minus dry weight divided by wet weight multiplied by 100%. When the moisture content is below 15%, the material has insufficient bonding force and the particles are easily broken. When it is above 28%, the material adheres and is difficult to form.The two rollers of the double-roller extrusion granulator have die holes on their surfaces. The roller pressure of 15 to 25 MPa compresses the material and extrudes it through the die holes. The roller speed ratio of 1:1.1 to 1:1.3 allows one roller to rotate slightly faster, generating shear force to help the material enter the die holes. The extruded strip is cut into cylindrical particles with a length of 3 to 6 mm by a rotary cutter. Extrusion granulation makes the internal structure of the particles dense, with a compressive strength of 20 to 35 Newtons per particle. During the vibrating fluidized bed drying process, the inlet air temperature is 70 to 90 degrees Celsius, and the bed temperature is 55 to 65 degrees Celsius to avoid damage to microbial activity due to excessive temperature. The vibration frequency is 15 to 25 Hz to ensure that the particles tumble and are heated evenly in the bed. The residence time is 40 to 60 minutes, and the moisture content at the drying endpoint is controlled below 8%. Too high a moisture content will cause microorganisms to activate prematurely and consume nutrients during storage, while too low a moisture content will cause the particle cracking strength to decrease. Vibrating screen grading classifies particles with a diameter of 2 to 4 mm as qualified products, with a yield of 75% to 85%. Fine powder smaller than 2 mm and coarse particles larger than 4 mm are returned to the mixing process for regranulation, achieving material recycling. A sodium alginate-chitosan mixture is sprayed onto the particle surface to form a bioprotective film, with a coating amount of 2% to 4% of the particle mass and a film thickness of 15 to 30 micrometers. This film prevents particle breakage and pulverization during transportation and distribution, reducing the wear rate from 8% to 12% of the uncoated material to less than 3%. The film gradually dissolves in water, delaying the rapid dissolution of the core components. Complete dissolution time at 25 degrees Celsius is 24 to 48 hours. Sodium alginate and chitosan can be degraded by microorganisms into carbon and nitrogen sources without introducing secondary pollution.

[0019] In one specific embodiment, step S1 includes: After dispersing the mesoporous silica support in ethanol solvent, a silane coupling agent was added and refluxed. After filtration, washing and drying, amino-modified mesoporous silica was obtained. Amino-modified mesoporous silica was dispersed in an aqueous solution, and a sulfur-containing reagent was added dropwise. A condensing agent was added simultaneously to promote the formation of amide bonds. After reaction, washing, and drying, a thiol-amino bifunctional adsorbent material was obtained. After oxygen-limited carbonization, biochar was subjected to reflux oxidation with nitric acid solution to introduce carboxyl functional groups. After washing and drying, carboxylated biochar was obtained. A gradient pore size composite adsorbent was obtained by dry mixing of thiol-amino bifunctional adsorbent material and carboxylated biochar.

[0020] Specifically, the mesoporous silica support is dispersed in anhydrous ethanol at a material-to-liquid ratio of 1:8 g / mL. The stirring speed is controlled at 60 to 80 degrees Celsius to ensure thorough dispersion of the support. The amount of silane coupling agent KH-550 added is calculated as 8% to 12% of the support mass. In the KH-550 molecule, the ethoxysilane end undergoes a hydrolysis reaction in the ethanol solvent to generate silanol groups. The silanol groups undergo a dehydration condensation reaction with the silanol groups on the surface of the mesoporous silica to form Si-O-Si covalent bonds. At the same time, the aminopropyl group at the other end of the molecule is introduced into the material surface. The reflux reaction temperature is maintained at 75 to 85 degrees Celsius for 4 to 6 hours, and the stirring speed is 300 to 400 rpm to ensure uniform mass transfer. After the reaction, the solid and liquid are separated by vacuum filtration. The material is washed 3 to 5 times with anhydrous ethanol to remove unreacted silane coupling agent and byproduct ethanol. The material is dried in a vacuum drying oven at 80 to 100 degrees Celsius for 8 to 12 hours to remove residual solvent, resulting in a modified material with uniformly distributed amino functional groups on the surface. Amino-modified mesoporous silica was dispersed in deionized water to prepare a suspension with a concentration of 15% to 20%. 3-Mercaptopropionic acid was added dropwise as a sulfur-containing reagent, with the amount added calculated as 1.2 to 1.5 times the molar amount of amino in the material. Condensing agents EDC and NHS were added simultaneously in a molar ratio of EDC to NHS to amino of 2:1.5:1. EDC first reacts with the carboxyl group of 3-mercaptopropionic acid to form an O-acylisourea intermediate. NHS reacts with the intermediate to generate an NHS active ester. The positively charged carboxyl carbon atom of this active ester is subjected to nucleophilic attack by the amino group, and the lone pair electrons of the nitrogen atom form a new carbon-nitrogen bond with the carboxyl carbon. Simultaneously, NHS leaves, completing the formation of the amide bond. The pH of the reaction system was adjusted to 5.5 to 6.5 to keep the carboxyl groups in a semi-deprotonated state to facilitate activation, while maintaining the moderate nucleophilicity of the amino groups. The reaction temperature was 25 to 35 degrees Celsius to avoid hydrolysis of the condensing agent. The reaction time was 8 to 10 hours to allow the thiol grafting to reach saturation. The thiol content was determined by the Ellman reagent colorimetric method. The Ellman reagent 5,5'-dithiobis(2-nitrobenzoic acid) reacts with the thiol groups to generate a yellow product, 2-nitro-5-thiobenzoate ion. The absorbance was measured at a wavelength of 412 nm. According to the Lambert-Beer law, the absorbance is directly proportional to the thiol concentration. A thiol content of 1.8 to 2.5 mmol / g indicates successful modification.Biochar raw materials, such as bamboo charcoal or straw charcoal, are carbonized under oxygen-limited conditions at a temperature of 700-800 degrees Celsius for 2-3 hours. This oxygen-limited environment is achieved by filling the container with nitrogen or using a sealed container. During carbonization, the cellulose, hemicellulose, and lignin in the biomass undergo pyrolysis, removing volatile matter and moisture to form a charcoal material rich in aromatic carbon skeletons. The carbonized biochar is then mixed with a 30%-40% nitric acid solution at a ratio of 1:10 g / mL and refluxed at 80-90 degrees Celsius for 4-6 hours. Nitric acid acts as a strong oxidizing agent. In this reaction, the nitrogen atom in the nitrate ion is in its highest oxidation state with a valence of +5, and it electrophilically attacks the aromatic carbon atoms on the surface of biochar, oxidizing the carbon atoms to carboxyl functional groups. During the reaction, nitric acid is reduced to nitrogen oxide gas and escapes. The carboxyl content is determined by the Boehm titration method. The sample is dispersed in sodium hydroxide solution to neutralize the carboxyl groups with hydroxide ions. Excess hydroxide ions are back-titrated with standard hydrochloric acid solution. The carboxyl content is calculated based on the number of moles of hydroxide ions consumed. A carboxyl content of 2.0 to 3.2 mmol / g meets the requirements. Thiol-amino bifunctional adsorbent material and carboxylated biochar were dry-mixed at a mass ratio of 3:2 in a high-speed mixer at a speed of 1500 to 2000 rpm for 20 to 30 minutes. This high-speed mixing ensured thorough dispersion and interweaving of the two materials, forming a composite structure with a gradient pore size distribution. Mesoporous silica provided a macroporous layer with a pore size of 100 to 200 nm, a mesoporous layer with a pore size of 10 to 50 nm, and a microporous layer with a pore size less than 2 nm. The pores formed after biochar carbonization were mainly concentrated in the mesoporous and macroporous ranges. The specific surface area of ​​the composite material was determined by the BET nitrogen adsorption method. The adsorption isotherm of nitrogen was measured at 77 Kelvin in liquid nitrogen, and the specific surface area was calculated according to the BET equation, reaching 520 to 680 m² / g. The total pore volume was calculated to be 0.45 to 0.65 cm³ / g using nitrogen adsorption-desorption curves. The pore size distribution was obtained by analyzing the desorption curves using the BJH method.

[0021] In one specific embodiment, step S2 includes: Ferrous sulfate and sodium thiosulfate were mixed in a molar ratio and then compounded and ground with hydroxyapatite precursor to obtain a passivating agent mixture. The passivating agent mixture and the gradient pore size composite adsorbent were mixed at a certain mass ratio and then dispersed in a sodium alginate solution to form a uniform suspension. The suspension was added dropwise to a calcium chloride solution for ionic cross-linking and solidification to form calcium alginate microcapsules. Calcium alginate microcapsules were immersed in chitosan solution for polyelectrolyte composite membrane coating, and after rinsing and drying, double-layer sustained-release passivated microcapsules were obtained.

[0022] Specifically, the mixture of ferrous sulfate and sodium thiosulfate in a molar ratio of 2:1 is based on the metabolic needs of sulfate-reducing bacteria under anaerobic conditions. Under anaerobic conditions, sulfate-reducing bacteria use sulfate ions as electron acceptors for respiration, reducing sulfate ions to sulfide ions. Sodium thiosulfate, as an intermediate oxidized sulfur source, is more easily utilized by microorganisms to convert into sulfide ions. Ferrous ions react in situ with sulfide ions produced by microorganisms to generate ferrous sulfide precipitate. Ferrous sulfide is further converted into stable iron sulfides such as pyrrhotite. These iron sulfides embed heavy metals into the crystal lattice through isomorphous substitution and capture heavy metal cations through electrostatic attraction of the surface negative charge. Hydroxyapatite precursors are prepared by co-precipitation of calcium chloride and diammonium hydrogen phosphate at a calcium-to-phosphorus molar ratio of 5:3. The resulting hydroxyapatite crystal nuclei are calcined at 500-600°C to perfect the crystal structure. In the hydroxyapatite lattice, calcium ions undergo isomorphous substitution with lead or cadmium ions to form metal phosphate minerals. The solubility product constant is reduced to the order of 10⁻⁸ to 10⁻⁸⁵, far lower than that of sulfide precipitation, achieving ultra-stable fixation of heavy metals. A passivating agent mixture and a gradient pore size composite adsorbent are mixed at a mass ratio of 1.5:1 and dispersed in a sodium alginate solution. Sodium alginate is a linear polysaccharide whose carboxyl groups deprotonate under neutral to weakly alkaline conditions to form negatively charged carboxylate ions. The suspension is uniformly dispersed at a solid-liquid ratio of 1:4 to 1:6 g / mL under mechanical stirring at 400-600 rpm. The suspension is added dropwise to the calcium chloride solution using a syringe or peristaltic pump. The drop height is 8 to 12 cm to give the droplets appropriate kinetic energy to penetrate the liquid surface without breaking. Calcium ions undergo ionic cross-linking with sodium alginate carboxylate ions. Each calcium ion simultaneously binds to two carboxylate ions to form an egg-box structure cross-linking network. Under the action of surface tension, the droplets become spherical. The cross-linking reaction proceeds from the surface of the droplets to the interior. After solidification in the calcium chloride solution for 20 to 30 minutes, spherical calcium alginate microcapsules are formed. The microcapsule particle size is controlled at 2.5 to 4.0 mm, and the interior is encapsulated with passivating agents and adsorbent materials. Calcium alginate microcapsules are immersed in a chitosan solution. Under acidic conditions, the amino groups of the chitosan molecular chains are protonated to form positively charged ammonium ions. The positive charge of chitosan and the negative charge of residual carboxylate ions on the microcapsule surface are electrostatically attracted to form a polyelectrolyte composite membrane. Chitosan molecular chains are deposited layer by layer on the surface of the microcapsules. The immersion time is 30 to 50 minutes to achieve a membrane thickness of 40 to 80 micrometers. This composite membrane is responsive to redox potential. Under anaerobic low potential conditions, the glycosidic bonds and amino groups of chitosan molecular chains undergo reducing chain scission, increasing the membrane porosity and promoting the outward diffusion of the core material. Under aerobic high potential conditions, the membrane structure is compact and the release rate is reduced. After rinsing with deionized water to remove residual calcium ions and chitosan from the surface, the microcapsules are dried at 30 to 40 degrees Celsius until the water content is less than 10% to obtain double-layered sustained-release passivated microcapsules.

[0023] In one specific embodiment, step S3 includes: Riboflavin was dissolved in deionized water, and after adding a solubilizer, it was heated and stirred in a water bath until completely dissolved. After cooling to room temperature, riboflavin mother liquor was obtained. Sodium humate was dissolved in an alkaline solution and stirred until completely dissolved to obtain humic acid mother liquor. Sodium acetate and glucose were mixed and dissolved in deionized water in a certain mass ratio to obtain a carbon source mother liquor; ammonium chloride and potassium dihydrogen phosphate were mixed in a certain molar ratio and then dissolved in a trace element mixture to obtain a nutrient salt mother liquor. After mixing riboflavin mother liquor, humic acid mother liquor, carbon source mother liquor and nutrient salt mother liquor in a volume ratio, adding homoserine lactone signaling molecules and stabilizers, and adjusting the pH, an anaerobic metabolism enhancer concentrate was obtained.

[0024] Specifically, when dissolving riboflavin in deionized water, a material-to-liquid ratio of 1:20 g / mL is used. Due to the low solubility of riboflavin in water, polyethylene glycol-400 is added as a solubilizer at a rate of 2% to 3% of the total solution mass. The ether oxygen atoms in the polyethylene glycol molecule form hydrogen bonds with the riboflavin molecule to enhance solubility. The water bath heating temperature is controlled at 40 to 50 degrees Celsius, and the mixture is stirred until the riboflavin is completely dissolved. The heating temperature should not be too high to avoid thermal decomposition of the isofluoroazine ring system in the riboflavin molecule. After cooling to room temperature, a riboflavin mother liquor is obtained. Riboflavin acts as an extracellular electron shuttle in anaerobic metabolism. Its isofluoroazine ring can reversibly switch between oxidized and reduced states. The reduced riboflavin accepts electrons released by methanogens and then transfers the electrons to iron ions or sulfate ions, reducing the activation energy of electron transfer and accelerating the methanogenesis process. Sodium humate is dissolved in an alkaline solution prepared with sodium hydroxide, and the pH of the solution is adjusted to 9 to 10. Under alkaline conditions, the carboxyl and phenolic hydroxyl groups of humic acid deprotonate to form carboxylate and phenolic anions, increasing the solubility to 15 to 25 g / L. Stirring for 1 to 2 hours ensures complete dissolution, yielding a humic acid mother liquor. The quinone group in the humic acid molecule acts as an electron shuttle under anaerobic conditions, reversibly transferring electrons between the quinone and hydroquinone forms, forming a complementary potential gradient with riboflavin to promote electron transfer between different microbial populations. Sodium acetate and glucose are mixed at a mass ratio of 2:1 and dissolved in deionized water. This ratio is based on the staged theory of anaerobic digestion. Glucose is fermented by acid-producing bacteria to produce volatile fatty acids, including acetate, propionate, and butyric acid. Acetic acid is a direct substrate for methanogens. Initially, a high concentration of carbon source is added to quickly initiate the hydrolysis, acidification, and acetic acid production stages. Later, a low concentration is maintained to avoid the accumulation of volatile fatty acids, which would cause a pH drop and inhibit methanogens. A carbon source mother liquor with a concentration of 30% to 40% is prepared. Ammonium chloride and potassium dihydrogen phosphate are mixed at a molar ratio of 5:1, which matches the nutritional requirements of anaerobic microorganisms with a carbon-nitrogen-phosphorus mass ratio of 100:5:1. Ammonium chloride provides nitrogen for the synthesis of amino acids and nucleic acids, while potassium dihydrogen phosphate provides phosphorus for the synthesis of nucleic acids and phospholipids and provides potassium ions to maintain cell osmotic pressure. The added trace element mixture includes ferric chloride, manganese sulfate, cobalt chloride, nickel chloride, and sodium molybdate. These trace elements are cofactors of key enzymes in anaerobic metabolism. Nickel ions are the active center of urease and carbon monoxide dehydrogenase, cobalt ions are the core element of vitamin B12, and molybdenum is a cofactor of formate dehydrogenase. The mixture is dissolved to prepare a nutrient salt stock solution with a concentration of 15% to 20%.Riboflavin mother liquor, humic acid mother liquor, carbon source mother liquor, and nutrient salt mother liquor were mixed at a volume ratio of 1:1.5:3:1. During mixing, mechanical stirring was performed at 300-500 rpm for 30-50 minutes to ensure uniformity. The concentration of N-3-hydroxy-dodecyl-homoserine lactone signaling molecule was controlled at 10-50 nanomoles per liter. This signaling molecule belongs to the acylhomoserine lactone class of quorum sensing signals. After binding to LuxR-type transcriptional regulatory proteins of Gram-negative bacteria, this complex binds to the gene promoter region and activates... Active transcription was performed to upregulate the expression of nitrate reductase, nitrite reductase, and methyl coenzyme M reductase genes. Trehalose was added as a stabilizer at a concentration of 2% to 3% of the total mass of the mixture. Trehalose is a non-reducing disaccharide that forms a glassy structure under dehydration conditions to protect the activity of microbial enzymes. The pH was adjusted to 6.8 to 7.2 to obtain a concentrated anaerobic metabolism enhancer solution. This concentrated solution has a stability period of more than 6 months under refrigeration at 4 degrees Celsius. When using, it should be diluted 1:50 to 1:100 and added to the sediment remediation site.

[0025] In one specific embodiment, step S4 includes: Nickel sulfate was dissolved in deionized water to prepare a urease activator stock solution; manganese sulfate and cobalt chloride were mixed in a molar ratio and dissolved to prepare a phosphatase activator stock solution. The cellulase complex and protease complex were mixed in a certain mass ratio and then dispersed in a phosphate buffer containing trehalose to obtain an enzyme preparation solution. Metronidazole and sodium molybdate were mixed to prepare an inhibitor stock solution; Urease activator stock solution, phosphatase activator stock solution, enzyme preparation solution and inhibitor stock solution are mixed in volume ratio, and surfactant is added to adjust the pH. Then, the mixture is anaerobically activated with indigenous microbial concentrate to obtain indigenous microbial community targeted activator.

[0026] Specifically, when dissolving riboflavin in deionized water, a material-to-liquid ratio of 1:20 g / mL is used. Due to the low solubility of riboflavin in water, polyethylene glycol-400 is added as a solubilizer at a rate of 2% to 3% of the total solution mass. The ether oxygen atoms in the polyethylene glycol molecule form hydrogen bonds with the riboflavin molecule to enhance solubility. The water bath heating temperature is controlled at 40 to 50 degrees Celsius, and the mixture is stirred until the riboflavin is completely dissolved. The heating temperature should not be too high to avoid thermal decomposition of the isofluoroazine ring system in the riboflavin molecule. After cooling to room temperature, a riboflavin mother liquor is obtained. Riboflavin acts as an extracellular electron shuttle in anaerobic metabolism. Its isofluoroazine ring can reversibly switch between oxidized and reduced states. The reduced riboflavin accepts electrons released by methanogens and then transfers the electrons to iron ions or sulfate ions, reducing the activation energy of electron transfer and accelerating the methanogenesis process. Sodium humate is dissolved in an alkaline solution prepared with sodium hydroxide, and the pH of the solution is adjusted to 9 to 10. Under alkaline conditions, the carboxyl and phenolic hydroxyl groups of humic acid deprotonate to form carboxylate and phenolic anions, increasing the solubility to 15 to 25 g / L. Stirring for 1 to 2 hours ensures complete dissolution, yielding a humic acid mother liquor. The quinone group in the humic acid molecule acts as an electron shuttle under anaerobic conditions, reversibly transferring electrons between the quinone and hydroquinone forms, forming a complementary potential gradient with riboflavin to promote electron transfer between different microbial populations. Sodium acetate and glucose are mixed at a mass ratio of 2:1 and dissolved in deionized water. This ratio is based on the staged theory of anaerobic digestion. Glucose is fermented by acid-producing bacteria to produce volatile fatty acids, including acetate, propionate, and butyric acid. Acetic acid is a direct substrate for methanogens. Initially, a high concentration of carbon source is added to quickly initiate the hydrolysis, acidification, and acetic acid production stages. Later, a low concentration is maintained to avoid the accumulation of volatile fatty acids, which would cause a pH drop and inhibit methanogens. A carbon source mother liquor with a concentration of 30% to 40% is prepared. Ammonium chloride and potassium dihydrogen phosphate are mixed at a molar ratio of 5:1, which matches the nutritional requirements of anaerobic microorganisms with a carbon-nitrogen-phosphorus mass ratio of 100:5:1. Ammonium chloride provides nitrogen for the synthesis of amino acids and nucleic acids, while potassium dihydrogen phosphate provides phosphorus for the synthesis of nucleic acids and phospholipids and provides potassium ions to maintain cell osmotic pressure. The added trace element mixture includes ferric chloride, manganese sulfate, cobalt chloride, nickel chloride, and sodium molybdate. These trace elements are cofactors of key enzymes in anaerobic metabolism. Nickel ions are the active center of urease and carbon monoxide dehydrogenase, cobalt ions are the core element of vitamin B12, and molybdenum is a cofactor of formate dehydrogenase. The mixture is dissolved to prepare a nutrient salt stock solution with a concentration of 15% to 20%.Riboflavin mother liquor, humic acid mother liquor, carbon source mother liquor, and nutrient salt mother liquor were mixed at a volume ratio of 1:1.5:3:1. During mixing, mechanical stirring was performed at 300-500 rpm for 30-50 minutes to ensure uniformity. The concentration of N-3-hydroxy-dodecyl-homoserine lactone signaling molecule was controlled at 10-50 nanomoles per liter. This signaling molecule belongs to the acylhomoserine lactone class of quorum sensing signals. After binding to LuxR-type transcriptional regulatory proteins of Gram-negative bacteria, this complex binds to the gene promoter region and activates... Active transcription was performed to upregulate the expression of nitrate reductase, nitrite reductase, and methyl coenzyme M reductase genes. Trehalose was added as a stabilizer at a concentration of 2% to 3% of the total mass of the mixture. Trehalose is a non-reducing disaccharide that forms a glassy structure under dehydration conditions to protect the activity of microbial enzymes. The pH was adjusted to 6.8 to 7.2 to obtain a concentrated anaerobic metabolism enhancer solution. This concentrated solution has a stability period of more than 6 months under refrigeration at 4 degrees Celsius. When using, it should be diluted 1:50 to 1:100 and added to the sediment remediation site.

[0027] In one specific embodiment, step S5 includes: Calcium carbonate and magnesium hydroxide are mixed in a certain mass ratio to serve as an anti-acidification buffer, and ferrous sulfate and sulfur powder are mixed in a certain mass ratio to serve as an anti-alkaliification buffer. The two are then compounded in a certain mass ratio to obtain a pH buffer mixture. Calcium peroxide and sodium lactate were mixed in a certain mass ratio, and then compounded with humic acid in the humic acid mother liquor to obtain an Eh regulator mixture. After the pH buffer mixture and the Eh regulator mixture are compounded in a certain mass ratio, they are added to a polyvinyl alcohol aqueous solution and mixed and granulated in a twin-screw extruder. After hot air drying, buffer granules are obtained. The buffer particles were coated with an ethyl cellulose alcohol solution in a fluidized bed to prepare a coating layer, and then subjected to a post-curing treatment to obtain pH-Eh synergistic buffer particles.

[0028] Specifically, calcium carbonate and magnesium hydroxide are mixed in a 3:1 mass ratio as an anti-acidification buffer. Calcium carbonate reacts rapidly with acid, quickly neutralizing volatile fatty acids produced by anaerobic degradation of sediment. The reaction generates calcium ions, which then react with water and carbon dioxide. Magnesium hydroxide, with its low solubility, provides a long-lasting buffer, generating magnesium ions, which then react with water. This combination achieves a combination of rapid response and long-lasting buffering. Ferrous sulfate and sulfur powder are mixed in a 2:1 mass ratio as an anti-alkaliification buffer. Ferrous ions are oxidized under slightly aerobic conditions to produce hydrogen ions. Four ferrous ions, plus oxygen and ten water molecules, produce four ferric hydroxide precipitates and eight hydrogen ions. Sulfur powder is oxidized by sulfur-oxidizing bacteria to produce sulfuric acid, releasing hydrogen ions and lowering the pH. Two elemental sulfur molecules, plus three oxygen molecules and two water molecules, produce two sulfuric acid molecules. An anti-acidification buffer and an anti-alkaliification buffer are mixed in a 4:1 mass ratio to obtain a pH buffer mixture based on the actual situation that the risk of sediment acidification is greater than the risk of alkaliification. Calcium peroxide and sodium lactate are mixed at a mass ratio of 3:2. Calcium peroxide slowly hydrolyzes in water, with two calcium peroxide molecules adding two water molecules to produce two calcium hydroxide molecules and oxygen. The released oxygen creates a microaerobic environment with dissolved oxygen of 0.2 to 0.5 mg / L on the surface of the sediment. Sodium lactate is oxidized under anaerobic conditions, with lactate ions adding water to produce acetate ions, bicarbonate ions, four hydrogen ions, and four electrons. The released electrons are used for sulfate reduction and iron reduction, maintaining the redox potential of the deep sediment layer at -150 to -100 mV. The calcium peroxide and sodium lactate mixture is then compounded with humic acid from the humic acid mother liquor at a mass ratio of 3:2:1. Humic acid acts as an electron shuttle, promoting electron transfer to obtain an Eh regulator mixture. The pH buffer mixture and Eh regulator mixture are compounded at a mass ratio of 3:1 and then added to a polyvinyl alcohol aqueous solution with a polyvinyl alcohol concentration of 5% to 8% and a material-to-liquid ratio controlled at 1:1.2 to 1:1.5 g / mL. The hydroxyl groups of the polyvinyl alcohol molecular chain form hydrogen bonds with the surface of the buffer particles, which acts as a binder. The mixture is then fed into a twin-screw extruder for mixing and granulation. The screw temperature is 60 to 80 degrees Celsius, which partially dissolves the polyvinyl alcohol to form a viscous matrix. The speed is 80 to 120 rpm, and the extrusion pressure is 2 to 4 MPa to extrude the material from the die to form strips. The material is then dried with hot air at an inlet temperature of 70 to 90 degrees Celsius and a bed temperature of 55 to 65 degrees Celsius for a residence time of 40 to 60 minutes. During the drying process, the water evaporates and the polyvinyl alcohol solidifies to form a granular skeleton, resulting in buffer particles.The buffer particles are placed in a fluidized bed and suspended by an upward airflow, thus achieving a fluidized state. Ethyl cellulose is dissolved in 95% ethanol to prepare a coating solution with a concentration of 8% to 12%, which is then sprayed onto the particle surface through an atomizing nozzle. The inlet air temperature is 60 to 70 degrees Celsius, the air velocity is 1.5 to 2.5 meters per second, and the spraying rate is 2 to 3 grams per minute. The ethanol evaporates rapidly, leaving an ethyl cellulose membrane. The coating thickness is controlled to be 30 to 60 micrometers by the spraying time. After coating, the particles are post-cured at 50 to 60 degrees Celsius for 2 to 3 hours. Post-curing relaxes the internal stress of the coating membrane, increases the membrane density, and enhances the membrane strength. The ethyl cellulose membrane slowly dissolves in water, controlling the release rate of the core material to obtain pH-Eh synergistic buffer particles.

[0029] In one specific embodiment, step S6 includes: Gradient pore size composite adsorbent material, double-layer slow-release passivation microcapsules and pH-Eh synergistic buffer particles were added to a high-speed mixer at a dry basis mass ratio to obtain a solid mixture. The anaerobic metabolism enhancer concentrate and the indigenous microbial community targeted activator were sprayed evenly onto the surface of the solid mixture to obtain a wet mixture. Bentonite, sodium carboxymethyl cellulose and molasses are used as composite binders and ammonium bicarbonate is used as a pore-forming agent. They are then added to the wet mixture and mixed. The mixture is then fed into a roller extrusion granulator for extrusion granulation. After drying in a vibrating fluidized bed, the mixture is classified by a vibrating screen to obtain qualified granules. The qualified granules were placed in a fluidized bed coating machine and sprayed with a sodium alginate-chitosan mixture for surface coating. After cooling and foreign matter detection, they were vacuum packaged to obtain the conditioner.

[0030] Specifically, gradient pore size composite adsorbent bilayer slow-release passivated microcapsules and pH-Eh synergistic buffer particles are fed into a high-speed mixer at a dry basis mass ratio of 2:3:2. This ratio is based on the functional positioning of each component. The adsorbent material is responsible for the rapid capture of pollutants, the passivated microcapsules provide long-term support for heavy metal fixation and organic matter degradation, and the buffer particles maintain the stability of the micro-ecological environment. The mixer adopts a V-type or double-cone type with an effective volume of 200 to 500 liters, a filling coefficient of 0.4 to 0.6, a mixing speed of 30 to 50 revolutions per minute, and a mixing time of 30 to 50 minutes to ensure uniform dispersion of each component. The mixing uniformity is calculated by measuring the content of each component at 10 random sampling points and calculating the coefficient of variation. The coefficient of variation is equal to the standard deviation divided by the mean multiplied by 100%. A coefficient of variation of less than 5% indicates that the mixture is uniform and a solid mixture is obtained. The anaerobic metabolism enhancer concentrate and the indigenous microbial community targeted activator are atomized by spraying at a pressure of 0.2 to 0.4 MPa into droplets with a diameter of less than 50 micrometers. The atomization mechanism is that when the liquid passes through the nozzle under high pressure, the shear force overcomes the surface tension, causing the liquid flow to break into fine droplets. The droplets are evenly distributed on the surface of the solid particles. Through capillary action, the droplets penetrate into the interior along the pores on the particle surface. Surface adsorption causes the liquid components to adhere to the particle surface and internal pores. The total amount of liquid components added is 8% to 12% of the mass of the solid mixture to obtain a wet-mixed material. Bentonite is added as an inorganic binder at a rate of 5% to 8% of the dry basis mass of the wet-mixed material. The main component of bentonite is montmorillonite. There are exchangeable cations such as sodium and calcium ions between the crystal layers of montmorillonite. After absorbing water, water molecules enter the interlayer space, causing the cations to hydrate. The interlayer spacing increases from about 1 nanometer to about 2 to 4 nanometers. Macroscopically, this manifests as the bentonite volume expanding by 15 to 20 times, forming a gel network. The gel network encapsulates and binds the various component particles together. Sodium carboxymethyl cellulose is added at a concentration of 2% to 4%. The carboxyl groups on the sodium carboxymethyl cellulose molecular chain cross-link with calcium or magnesium ions. A divalent metal ion simultaneously binds to two carboxyl groups to form a coordinate bond. Multiple molecular chains are bridged by metal ions to form a three-dimensional network structure, which enhances the internal bonding strength of the particles. Molasses is added at a concentration of 3% to 5%. Molasses contains reducing sugars such as sucrose, glucose, and fructose, as well as non-reducing sugars. During the drying process, water evaporates, increasing the sugar concentration. When the sugar concentration exceeds the saturation concentration, the hydrogen bonding between sugar molecules strengthens. When the temperature drops below the glass transition temperature, the sugars form a glassy state. Glassy sugar molecules are highly disordered but have strong intermolecular forces, resulting in high mechanical strength and binding force. The amount of ammonium bicarbonate added is 3% to 5%. Ammonium bicarbonate has poor thermal stability and begins to decompose when the temperature exceeds 36 degrees Celsius during the drying process. The decomposition reaction is that ammonium bicarbonate produces ammonia, water vapor and carbon dioxide. The three gas products gather inside the particles to form bubbles. The bubbles expand and compress the surrounding material to form channels. The pore size is mainly distributed in the range of 5 to 20 micrometers, and the porosity reaches 20% to 30%. The channels increase the specific surface area and water permeation channels.The moisture content of the material is detected by a rapid moisture analyzer. The detection principle is to place the sample on a 105-degree Celsius heating plate, where an infrared heater rapidly evaporates the moisture, and an electronic balance monitors the mass change in real time. When the rate of mass change is lower than a set threshold, the drying endpoint is determined. The moisture content is calculated as the difference between the initial mass and the dried mass, divided by the initial mass and multiplied by 100%. The moisture content is controlled between 18% and 25%. When the moisture content is below 15%, the bentonite and sodium carboxymethyl cellulose are not sufficiently gelled and have insufficient bonding force. When the moisture content is above 28%, the material is too wet and sticks to the roller surface, making it difficult to extrude and form. The double-roller extrusion granulator consists of two rollers that rotate relative to each other. The roller surfaces are regularly distributed with die holes, which are circular with a diameter of 3 to 6 mm. The roller pressure is 15 to 25 MPa. The material is subjected to enormous pressure in the gap between the rollers, and the voids between the particles are compressed and the material is densified. When the material is extruded from the die holes, it expands slightly due to the release of pressure, forming a strip-shaped extrudate. The rotating cutter is located on the outside of the rollers, with a blade gap of 0.5 to 1 mm from the roller surface. The cutter speed is matched with the roller linear speed, cutting the continuously extruded strip into cylindrical particles with a length of 3 to 6 mm. Vibrating fluidized bed drying utilizes the combined action of vibration and hot air. The bed vibrates at a frequency of 15 to 25 Hz with an amplitude of 2 to 5 mm. The vibration causes the particles to jump and tumble within the bed. Simultaneously, hot air is blown upwards from the bottom of the bed at a speed of 1 to 2 m / s and an inlet air temperature of 70 to 90 degrees Celsius. The particles are in full contact with the hot air, and surface moisture evaporates, carrying away heat. The bed temperature is stabilized at 55 to 65 degrees Celsius. During the drying process, ammonium bicarbonate decomposes and releases gas, creating pores inside the particles. The residence time is 40 to 60 minutes, reducing the particle moisture content to below 8%. The vibrating screen grading uses a multi-layer screen. The upper screen with 4 mm apertures screens out coarse particles larger than 4 mm, the middle screen with 2 mm apertures screens out qualified particles of 2 to 4 mm, and the bottom screen receives fine powder smaller than 2 mm. The vibration frequency is 20 to 30 Hz, the amplitude is 5 to 10 mm, and the sieving time is 5 to 10 minutes. The yield of qualified particles is 75% to 85%. The coarse particles are crushed by a crusher and returned to the mixing process with the fine powder for regranulation. The sodium alginate-chitosan mixture is prepared with a concentration of 1.5-2.5% sodium alginate, 1.0-1.5% chitosan, and 2-3% glycerol. Glycerol acts as a plasticizer to increase membrane flexibility and prevent cracking. The mixture is sprayed onto the surface of suspended particles in a fluidized bed through an atomizing nozzle. The bed temperature is 50-60 degrees Celsius, the spray pressure is 0.15-0.25 MPa, the atomizing air flow rate is 40-60 cubic meters per hour, the coating amount is 2%-4% of the particle mass, and the coating thickness is 15-30 micrometers. After coating, the particles are cooled to room temperature and then passed through an X-ray foreign matter detector. The detection principle is that X-rays have a strong ability to penetrate organic matter but a weak ability to penetrate metal. Metal impurities appear as high-density shadows in the X-ray image. Particles with detected metal impurities are rejected. Qualified particles are vacuum-packed in 25 kg bags. The vacuum degree is controlled to ensure that the residual oxygen content is less than 2%. Nitrogen gas is filled to protect the microbial activity and obtain the conditioner.

[0031] In one specific embodiment, bentonite, sodium carboxymethyl cellulose, and molasses are used as a composite binder and ammonium bicarbonate is used as a pore-forming agent. These are then added to a wet mixture and fed into a roller extrusion granulator for extrusion granulation. After drying in a vibrating fluidized bed, the mixture is classified by a vibrating screen to obtain qualified granules, including: Bentonite, sodium carboxymethyl cellulose and molasses were mixed in a mass ratio to form a composite binder system, which was then added to the wet mixture along with ammonium bicarbonate. After controlling the moisture content of the material, the material to be granulated was obtained. The material to be granulated is fed into a roller extrusion granulator for extrusion and densification. After being extruded through the die holes, it is cut into cylindrical wet granules by a rotary cutter. The wet particles are conveyed to a vibrating fluidized bed dryer for drying, and the dried particles are obtained after controlling the moisture content at the end of the drying process. After being cooled, the dried granules are fed into a vibrating screen for particle size classification. Particles within the target particle size range are screened out as qualified particles, while fine powder and coarse particles that do not meet the particle size requirements are returned to the granulation process.

[0032] Specifically, bentonite, sodium carboxymethyl cellulose, and molasses are mixed in a specific mass ratio to form a composite binder. The amount of bentonite added is 5% to 8% of the dry basis mass of the wet mixture as an inorganic binder. The bentonite absorbs water and swells to form a gel network that encapsulates the components. The amount of sodium carboxymethyl cellulose added is 2% to 4% as an organic binder. The carboxyl groups of the molecular chain crosslink with metal ions to form a three-dimensional network. The amount of molasses added is 3% to 5% as a biological binder. After drying, it forms a glassy structure to enhance strength. The amount of ammonium bicarbonate added is 3% to 5% as a pore-forming agent. During drying, it decomposes to generate gas that forms channels inside the particles. The composite binder and pore-forming agent are added to the wet mixture and mixed evenly. The moisture content is detected by a rapid moisture analyzer. The sample is heated at 105 degrees Celsius to evaporate the moisture. The mass change is monitored by an electronic balance. The moisture content is calculated as the initial mass minus the mass after drying divided by the initial mass. The moisture content is controlled between 18% and 25% to obtain the material to be granulated. The material to be granulated is fed into a roller extrusion granulator. The two rollers rotate relative to each other, with die holes distributed on their surfaces. A roller pressure of 15 to 25 MPa compacts the material. The material is compressed and densified within the gaps between the particles due to the pressure, and is extruded through the die holes. The extrudate expands slightly due to the release of pressure, forming strips. A rotating cutter is located on the outside of the rollers, with a blade clearance of 0.5 to 1 mm between the blade and the roller surface. The cutter's rotation speed matches the roller linear speed, cutting the strips into cylindrical wet granules with a length of 3 to 6 mm. The wet granules are then conveyed to a vibrating fluidized bed dryer. The bed vibrates at 15 to 25 Hz, causing the granules to jump and tumble. Hot air is blown from the bottom of the bed at an inlet temperature of 70 to 90 degrees Celsius. The moisture on the surface of the granules evaporates upon contact with the hot air. The bed temperature is 55 to 65 degrees Celsius, and the residence time is 40 to 60 minutes. During the drying process, ammonium bicarbonate decomposes to produce ammonia, water vapor, and carbon dioxide, creating pores inside the granules. The moisture content drops to below 8%, resulting in dried granules. After being cooled to room temperature, the dried granules are fed into a vibrating screen. The upper layer of the multi-layer screen with 4 mm mesh screens out coarse particles, the middle layer with 2 mm mesh screens out qualified particles of 2 to 4 mm, and the bottom layer receives fine powder. The vibration frequency is 20 to 30 Hz and the amplitude is 5 to 10 mm. The screening time is 5 to 10 minutes. The yield of qualified particles is 75% to 85%. The coarse particles are crushed and returned to the mixing process with the fine powder for regranulation.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a sediment micro-ecological reconstruction and pollutant targeted fixation conditioner, characterized in that, The method includes: Step S1: After sequentially modifying the mesoporous silica support with amination and thiolization, it is mixed with oxidized biochar to obtain a gradient pore size composite adsorbent material. Step S2: Ferrous sulfate, sodium thiosulfate and hydroxyapatite precursor are mixed and then dispersed together with the gradient pore size composite adsorbent in sodium alginate solution and added dropwise to calcium chloride solution for cross-linking. Then, the mixture is coated with chitosan to obtain a double-layer sustained-release passivated microcapsule. Step S3: After combining riboflavin, humic acid, carbon source and nutrients, add signaling molecules to obtain anaerobic metabolism enhancer concentrate. Step S4: After combining the metal salt activator, enzyme preparation and inhibitor, the mixture is activated by the indigenous microbial concentrate to obtain the indigenous microbial community targeted activator; Step S5: A pH buffer is prepared by mixing calcium carbonate-magnesium hydroxide with ferrous sulfate-sulfur powder, and an Eh regulator is prepared by mixing calcium peroxide with sodium lactate. The two are then compounded and granulated to obtain pH-Eh synergistic buffer particles. Step S6: Mix the gradient pore size composite adsorbent material, the double-layer slow-release passivation microcapsules and the pH-Eh synergistic buffer particles, spray in the anaerobic metabolism enhancer concentrate and the indigenous microbial community directional activator, add the composite binder and pore-forming agent, granulate by extrusion, dry and sieve, and then spray with a biological protective film to obtain the conditioner.

2. The preparation method of the sediment micro-ecological reconstruction and pollutant targeting fixation conditioner according to claim 1, characterized in that, Step S1 includes: After dispersing the mesoporous silica support in ethanol solvent, a silane coupling agent was added and refluxed. After filtration, washing and drying, amino-modified mesoporous silica was obtained. The amino-modified mesoporous silica was dispersed in an aqueous solution, a sulfur-containing reagent was added dropwise, and a condensing agent was added simultaneously to promote the formation of amide bonds. After reaction, washing and drying, a thiol-amino bifunctional adsorbent material was obtained. After oxygen-limited carbonization, biochar was subjected to reflux oxidation with nitric acid solution to introduce carboxyl functional groups. After washing and drying, carboxylated biochar was obtained. The thiol-amino bifunctional adsorbent material is dry-mixed with the carboxylated biochar to obtain the gradient pore size composite adsorbent material.

3. The preparation method of the sediment micro-ecological reconstruction and pollutant targeting fixation conditioner according to claim 1, characterized in that, Step S2 includes: Ferrous sulfate and sodium thiosulfate were mixed in a molar ratio and then compounded and ground with hydroxyapatite precursor to obtain a passivating agent mixture. The passivating agent mixture and the gradient pore size composite adsorbent are mixed at a certain mass ratio and then dispersed in a sodium alginate solution to form a uniform suspension. The suspension was added dropwise to a calcium chloride solution for ionic cross-linking and solidification to form calcium alginate microcapsules. The calcium alginate microcapsules were immersed in a chitosan solution for polyelectrolyte composite membrane coating, and after rinsing and drying, the double-layer sustained-release passivated microcapsules were obtained.

4. The preparation method of the sediment micro-ecological reconstruction and pollutant targeting fixation conditioner according to claim 1, characterized in that, Step S3 includes: Riboflavin was dissolved in deionized water, and after adding a solubilizer, it was heated and stirred in a water bath until completely dissolved. After cooling to room temperature, riboflavin mother liquor was obtained. Sodium humate was dissolved in an alkaline solution and stirred until completely dissolved to obtain humic acid mother liquor. Sodium acetate and glucose were mixed and dissolved in deionized water in a certain mass ratio to obtain a carbon source mother liquor; ammonium chloride and potassium dihydrogen phosphate were mixed in a certain molar ratio and then dissolved in a trace element mixture to obtain a nutrient salt mother liquor. The riboflavin mother liquor, the humic acid mother liquor, the carbon source mother liquor and the nutrient salt mother liquor are mixed in a volume ratio, then high-sirohydroxamate signal molecules and a stabilizer are added, and after pH adjustment, the anaerobic metabolism enhancer concentrate is obtained.

5. The preparation method of the sediment micro-ecological reconstruction and pollutant targeting fixation conditioner according to claim 4, characterized in that, The S4 step comprises: The urease activator stock solution is prepared by dissolving nickel sulfate in deionized water; the phosphatase activator stock solution is prepared by mixing manganese sulfate and cobalt chloride in a molar ratio and then dissolving and preparing; The cellulase complex and the protease complex are mixed in a mass ratio, then dispersed in a trehalose-containing phosphate buffer to obtain an enzyme preparation solution; The metronidazole and sodium molybdate are mixed to prepare an inhibitor stock solution; The urease activator stock solution, the phosphatase activator stock solution, the enzyme preparation solution and the inhibitor stock solution are mixed in a volume ratio, then a surfactant is added to adjust the pH, and then the indigenous microorganism concentrate is subjected to anaerobic activation to obtain the indigenous bacterial community directional activator.

6. The preparation method of the sediment micro-ecological reconstruction and pollutant targeting fixation conditioner according to claim 5, characterized in that, The S5 step comprises: Calcium carbonate and magnesium hydroxide are mixed in a mass ratio as an anti-acidification buffer, ferrous sulfate and sulfur powder are mixed in a mass ratio as an anti-alkalization buffer, and the two are compounded in a mass ratio to obtain a pH buffer mixture; Calcium peroxide and sodium lactate are mixed in a mass ratio, and then compounded with humic acid in the humic acid mother liquor to obtain an Eh regulator mixture; The pH buffer mixture and the Eh regulator mixture are compounded in a mass ratio, then polyvinyl alcohol aqueous solution is added and mixed in a twin-screw extruder to granulate, and then hot air drying is performed to obtain buffer granules; The buffer granules are placed in a fluidized bed to spray ethyl cellulose alcohol solution for coating layer preparation, and then post-aging treatment is performed to obtain the pH-Eh synergistic buffer granules.

7. The preparation method of the sediment micro-ecological reconstruction and pollutant targeting fixation conditioner according to claim 1, characterized in that, The S6 step comprises: The gradient pore size composite adsorbent material, the double-layer slow-release passivation microcapsule and the pH-Eh synergistic buffer granule are mixed in a high-speed mixer in a dry basis mass ratio to obtain a solid mixture; The anaerobic metabolism enhancer concentrate and the indigenous bacterial community directional activator are uniformly sprayed onto the surface of the solid mixture in a spray manner to obtain a wet mixed material; Bentonite, sodium carboxymethyl cellulose and molasses are used as a composite binder, and ammonium bicarbonate is used as a pore former, which are added to the wet mixed material and mixed, then extrusion granulation is performed in a pair of roller extrusion granulators, and then vibration fluidized bed drying is performed for vibration screening classification to obtain qualified granules; The qualified granules are placed in a fluidized bed coating machine to spray sodium alginate-chitosan mixed solution for surface coating, and then cooling and foreign matter detection are performed for vacuum packaging to obtain the conditioner.

8. The preparation method of the sediment micro-ecological reconstruction and pollutant targeting fixation conditioner according to claim 7, characterized in that, The bentonite, sodium carboxymethyl cellulose and molasses are used as a composite binder, the ammonium bicarbonate is used as a pore former, which are added to the wet mixed material, and then extrusion granulation is performed in a pair of roller extrusion granulators, and then the vibration fluidized bed drying is performed for vibration screening classification to obtain the qualified granules, which comprises: The bentonite, sodium carboxymethyl cellulose and molasses are compounded into a composite binder system in a mass ratio, and the ammonium bicarbonate is added to the wet mixed material, and then the moisture content of the material is controlled to obtain a material to be granulated; The material to be granulated is fed into a roller extrusion granulator for extrusion densification, and after being extruded through a die, it is cut into cylindrical wet granules by a rotary cutter. The wet particles are conveyed to a vibrating fluidized bed dryer for drying, and the moisture content at the drying endpoint is controlled to obtain dried particles. After cooling, the dried granules are fed into a vibrating screen for particle size classification. Particles within the target particle size range are screened out as qualified particles, while fine powder and coarse particles that do not meet the particle size requirements are returned to the granulation process.

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