Bottom mud environment in-situ remediation particles and preparation method thereof

Abstract

The invention relates to the technical field of environmental sludge treatment, in particular to sediment environment in-situ remediation particles and a preparation method thereof. The soil conditioner is prepared from the following raw materials: zeolite powder, volcanic rock powder, bentonite, silica sol, a functional component loaded precursor and bacillus spore powder. The sediment in-situ remediation particles are of a core-shell structure, activated zeolite-volcanic rock serves as an inner core to construct a porous framework, Fe / Mn and Mg / Ca loading sites are combined, pollutant adsorption, fixation and passivation are achieved, the sediment microenvironment is improved, conditions are created for outer-layer bacillus bioremediation, and space-time synergy of physicochemical and bioremediation is formed; a preparation route of curing nucleation and then low-temperature coating is adopted, the contradiction between mineral roasting and microorganism temperature intolerance is solved, the spore activity is guaranteed, and the loss resistance of the spore is improved.

Description

Technical Field

[0001] This invention relates to the field of environmental sludge treatment technology, specifically to an in-situ environmental remediation particle for sediment and its preparation method. Background Technology

[0002] Seabed sediments, as important sinks and potential sources of pollutants in water bodies, accumulate nitrogen, phosphorus, organic matter, and heavy metals over long periods. Under anoxic or anaerobic conditions, sediments are prone to enhanced reductive properties and sulfide formation, accompanied by the transformation of ammonia nitrogen, phosphate, and some metal forms, which are released into the overlying water, resulting in a continuous backflow of endogenous pollution. This leads to problems such as repeated eutrophication, black and odorous water, and water quality fluctuations. Therefore, developing efficient, stable, and engineering-feasible in-situ sediment remediation materials is a crucial requirement for river and lake management and the treatment of black and odorous water bodies.

[0003] Existing in-situ remediation technologies for sediment mainly include dredging, cover and isolation, addition of adsorbent / fixation materials, in-situ redox regulation, and bioremediation. While dredging can rapidly reduce pollution load, it involves large-scale engineering, high costs, and is prone to secondary disturbance and sediment disposal pressure. Cover and isolation can reduce sediment-water exchange, but requires materials with high erosion resistance and long-term stability, and it is difficult to simultaneously address the internal transformation and continuous release of pollutants within the sediment. Adding minerals or modified materials is widely used due to their relatively simple construction methods. Examples include zeolite, bentonite, volcanic rock powder, biochar, and modified minerals such as iron, calcium, and magnesium, which can be used to adsorb ammonium nitrogen, fix phosphates, or retain heavy metals. However, these materials often rely on a single mechanism and frequently suffer from insufficient synergistic control of multiple pollutants, diminishing effectiveness over time, easy dispersion or pulverization leading to turbidity and loss, and poor fixation stability in strongly reducing environments, all of which affect long-term remediation results.

[0004] Bioremediation, through the addition of functional microorganisms or the promotion of in-situ microbial community recovery, can enhance organic matter transformation and improve black and odorous conditions. However, in actual sediment environments, it is often constrained by factors such as sulfide toxicity, reducing fluctuations, salinity changes, and competition from native microorganisms. Exogenous bacteria are prone to slow recovery, unstable onset of action, dilution, or erosion. To improve the stability of engineering applications, carrier immobilization or slow-release protection is usually required. However, existing carrier systems are mostly used separately from inorganic immobilization materials, making it difficult to form an integrated, multi-target, and continuous remediation system. In addition, although existing technologies have proposed the combination of mineral materials and microorganisms to achieve both immobilization and bioremediation, the preparation of metal-modified minerals often involves acid / alkali treatment and calcination solidification steps. Microorganisms are sensitive to high temperatures and salinity, and there is a clear contradiction between the two being compatible and maintaining long-term activity in the same material. At the same time, the adsorption and burial of microorganisms or extracellular enzymes by mineral powders may also weaken the biological effect, leading to a simple superposition of the compound system, making it difficult to achieve stable synergy. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a sediment environmental in-situ remediation particle and its preparation method.

[0006] The technical effects described in this invention are achieved through the following technical solution: a sediment environment in-situ remediation particle, the composition of which includes the following raw materials: zeolite powder, volcanic rock powder, bentonite, silica sol, precursor of loaded functional components and Bacillus spore powder; Furthermore, the particle size of the zeolite powder and volcanic rock powder is 100-200 mesh; Furthermore, the precursor for the loaded functional component is composed of an iron source, a manganese source, a magnesium source, and a calcium source; Furthermore, the iron source is selected from either FeCl3 or Fe(NO3)3; Furthermore, the manganese source is selected from either MnSO4 or Mn(NO3)2; Furthermore, the magnesium source is selected from any one of MgCl2, MgSO4, and Mg(NO3)2; Furthermore, the calcium source is selected from any one of CaCl2, Ca(NO3)2, Ca(OH)2, and light CaCO3; Furthermore, the effective viable count of the Bacillus spore powder is 1×10⁻⁶. 9 ~10 10 CFU / g; Furthermore, another aspect of the present invention provides a method for preparing in-situ remediation particles for sediment environments, specifically comprising the following steps: S1: Weigh out zeolite powder, volcanic rock powder and bentonite according to the proportion, put them into a mixer and dry mix them to obtain a uniform mineral mixture powder; S2: Add the S1 mixed powder to a 0.5 mol / L HCl solution, stir at room temperature for 60 min, filter, wash with deionized water until the pH of the filtrate is 6.5-7; dry at 100-110℃ for 4-8 h to obtain acid-activated mineral powder; S3: Place the S2 acid-activated mineral powder in a muffle furnace for calcination and allow it to cool naturally to room temperature to obtain mineral carrier powder; S4: Prepare a mixed solution of 0.5–0.8 mol / L iron source and 0.05–0.1 mol / L manganese source with deionized water to obtain metal salt solution I; add S3 mineral carrier powder to metal salt solution I and stir at 50–70℃ for 50–80 min; adjust the pH to 8.3–8.7 by adding 2 mol / L NaOH dropwise, and continue stirring for 40–80 min; let stand for 3–5 h for aging, filter, and wash with deionized water until the conductivity of the filtrate is ≤50 µS / cm and the pH is neutral; dry at 80℃ for 4–8 h to obtain Fe / Mn supported powder; S5: Prepare a mixed solution of 0.3-0.5 mol / L magnesium source and 0.3-1 mol / L calcium source with deionized water to obtain metal salt solution II; add S4 Fe / Mn supported powder to metal salt solution II and stir at 50℃ for 60-90 min; adjust the pH to 9.3-9.7 with 1 mol / L Na2CO3 solution, continue stirring for 40-80 min, let stand for aging for 2-4 h, filter, wash with deionized water until the pH of the filtrate is neutral, and dry at 80℃ for 4-8 h to obtain Fe / Mn / Mg / Ca co-supported powder; S6: The S5 Fe / Mn / Mg / Ca co-loaded powder is calcined in air at 320-380℃ for 1-2 hours and then naturally cooled to room temperature to obtain solidified powder. S7: Add the S6 solidified powder to the granulation mixer, and spray silica sol and deionized water while mixing to make the moisture content of the wet material reach 20-30%. Mix the wet material to make it uniform and spherical. Then continuously feed it into the tray for granulation, controlling the particle size of the finished product to 1-3 mm. First, solidify it at 60℃ for 2-3 hours, and then dry it at 105℃ for 6-10 hours to make the moisture content of the finished product ≤8%, thus obtaining mineral functional core particles. S8: Prepare a 1-2 wt% sodium alginate solution with deionized water and stir to dissolve; add trehalose to make the concentration 1-3 wt%; after the solution cools to room temperature, add Bacillus spore powder and stir gently until homogeneous to obtain spore coating solution; S9: Place the mineral functional core particles from step S7 into a fluidized bed, spray the spore coating solution from step S8, immerse the wet particles in a 2-4 wt% CaCl2 solution for 10-20 min to cross-link the sodium alginate outer layer into a film, remove and drain, vacuum dry at 20-30℃ for 16-24 h to obtain in-situ repair particles. Further, in step S1, the mass ratio of zeolite powder, volcanic rock powder and bentonite is 10:6-7:0.6-0.8; Further, in step S2, the solid-liquid ratio of the mixed powder and the HCl solution is 1g:6-10mL; Furthermore, in step S3, the calcination temperature is 500–580°C, and the time is 1–3 hours; Further, in step S4, the solid-liquid ratio of the mineral carrier powder to the metal salt solution I is 1g:8-10mL; Further, in step S5, the solid-liquid ratio of the Fe / Mn supported powder and the metal salt solution II is 1g:8-12mL; Further, in step S7, the silica sol contains 30 wt% SiO2; and the amount of silica sol added, calculated as SiO2, is 1-3 wt% of the mass of the powder cured in S6. Furthermore, in step S7, the granulation disk angle is 40-60° and the rotation speed is 15-20 rpm; Further, in step S8, the activity of Bacillus in the spore coating solution is 1×10⁻⁶. 7 ~10 8 CFU / mL; Further, in step S8, the spraying parameters are: fluidized bed inlet air temperature 25-35℃, atomizing air pressure 0.1-0.25MPa, coating liquid spraying flow rate 15-30mL / min, and target coating weight gain 8-12wt%.

[0007] The beneficial effects of this invention are as follows: Compared to existing in-situ sediment remediation materials (single mineral adsorbents, single metal salt modifiers, or simple addition of microbial agents), the sediment environmental in-situ remediation particles of this invention adopt a core-shell integrated structure, organically coupling the porous mineral adsorption and chemical fixation of the core layer with the bioremediation effect of the outer Bacillus layer. This achieves simultaneous remediation of multiple targets and spatiotemporal synergy, thereby obtaining comprehensive effects that are difficult to achieve with single mineral adsorbents or simple addition of microbial agents. The particle core is constructed with activated zeolite and volcanic rock to form a porous framework and a high specific surface area interface, which can rapidly adsorb and exchange ionic components in the sediment pore water, reducing NH4. + This addresses the risk of releasing easily migratable pollutants. Based on this, loading sites such as Fe / Mn and Mg / Ca are introduced, enabling the core to simultaneously stabilize and passivate sulfide and reducing odor components. Phosphate is stabilized through precipitation and ion interactions, significantly reducing the release flux of nutrients and odor precursors. It also complexes or co-precipitates some dissolved metal ions for retention. This pre-treatment physicochemical purification and buffering process improves the redox environment at the sediment interface and reduces inhibitory factors, providing a buffer zone for the recovery and continuous metabolism of outer spores. This allows spores to more stably exert extracellular enzyme and metabolic competition under in-situ conditions, promoting organic matter transformation and inhibiting odor production. This forms a coupled synergistic mechanism of first fixing and buffering toxicity in the core, followed by bioremediation and enhanced efficacy in the outer layer.

[0008] To address the engineering contradiction that modified minerals require calcination and solidification to enhance load stability, while microorganisms are not temperature-resistant, this invention adopts a time-dependent preparation route of first solidifying and nucleating, followed by low-temperature film coating. By utilizing fluidized bed low-temperature spraying combined with a sodium alginate-calcium ion crosslinking system, a bioactive layer with certain semi-permeable and slow-release properties is formed on the surface of the mineral core. This maximizes the preservation of spore activity and significantly improves its resistance to erosion, dilution, and competitive inactivation, reducing the problems of easy loss and unstable onset of action during in-situ addition, and achieving a longer-lasting and more stable remediation process.

[0009] In terms of environmental friendliness and engineering practicality, this invention uses inorganic cementing systems such as silica sol for granulation and molding, which effectively reduces the risk of secondary organic load that may be caused by organic adhesives. The particle size is controlled at 1 to 3 mm, which has good settling performance and mechanical stability. After addition, it is not easy to generate dust and reduces the risk of pulverization and secondary turbidity. It can quickly locate at the bottom sediment interface to form a remediation layer with dual functions of adsorption and fixation and biodegradation, thereby improving the sensory black and odorous appearance while achieving synergistic reduction of nutrients and related pollutants.

[0010] In summary, this invention has significant advantages in terms of target coverage, duration of in-situ action, compatibility of materials and bioactivity, and feasibility. Furthermore, by solidifying the key sequence into the product structure and preparation route, it improves batch-to-batch consistency and reproducibility of effects. Attached Figure Description

[0011] Figure 1 To improve the NH4 content in the sediment overlying water during static release tests of particles in Examples 1 and 1-5 + Concentration change results graph; Figure 2 To improve the PO4 content in the sediment overlying water during static release tests of particles in Examples 1 and 1-5 3- Concentration change results graph; Figure 3 The graph shows the changes in the concentration of dissolved sulfides in the sediment overlying water during the static release test of the remediation particles in Example 1 and Comparative Examples 1-5. Figure 4 The graph shows the results of viable bacteria retention rate in the particle erosion test of Example 1 and Comparative Examples 2-4; Figure 5 In the continuous action test of the repair particles in Example 1 and Comparative Examples 1-5, PO4 was used. 3- Concentration change results graph; Figure 6 The graph shows the results of the viable bacteria retention rate of the repair particles in the continuous action test of Example 1 and Comparative Examples 1-5. Detailed Implementation

[0012] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the raw materials involved in the present invention are all purchased through conventional commercial channels. Experimental methods without specific conditions are conventional methods and conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0013] Example 1: A sediment remediation particle, comprising the following raw materials: zeolite powder, volcanic rock powder, bentonite, silica sol, precursor of loaded functional components, and Bacillus spore powder; The particle size of the zeolite powder and volcanic rock powder is 150 mesh; The effective viable count of the Bacillus spore powder is 5 × 10⁻⁶. 9 CFU / g; The preparation of the in-situ remediation particles for sediment environments specifically includes the following steps: S1: Weigh 100g of zeolite powder, 63g of volcanic rock powder and 7g of bentonite according to the ratio, put them into a mixer and dry mix them to obtain a uniform mineral mixture powder; S2: Add the S1 mixed powder to 160 mL of 0.5 mol / L HCl solution, stir at room temperature for 60 min, filter, and wash with deionized water until the pH of the filtrate is 6.8; dry at 105 °C for 6 h to obtain acid-activated mineral powder; S3: Place the S2 acid-activated mineral powder in a muffle furnace at 550℃ for 2 hours and let it cool naturally to room temperature to obtain mineral carrier powder; S4: Prepare a mixed solution of 0.6 mol / L Fe(NO3)3 and 0.06 mol / L Mn(NO3)2 with deionized water to obtain metal salt solution I; add S3 mineral carrier powder to 1530 mL of metal salt solution I and stir at 60℃ for 65 min; adjust the pH to 8.5 by adding 2 mol / L NaOH dropwise and continue stirring for 60 min; let stand for 4 h for aging, filter, wash with deionized water until the conductivity of the filtrate is ≤50 µS / cm and the pH is neutral; dry at 80℃ for 6 h to obtain Fe / Mn supported powder; S5: Prepare a mixed solution of 0.4 mol / L Mg(NO3)2 and 0.8 mol / L Ca(NO3)2 with deionized water to obtain metal salt solution II; add the S4 Fe / Mn supported powder to 1700 mL of metal salt solution II and stir at 50 °C for 80 min; adjust the pH to 9.5 with 1 mol / L Na2CO3 solution, continue stirring for 60 min, let stand for 3 h for aging, filter, wash with deionized water until the pH of the filtrate is neutral, and dry at 80 °C for 6 h to obtain Fe / Mn / Mg / Ca co-supported powder; S6: The S5 Fe / Mn / Mg / Ca co-loaded powder was calcined in air at 350℃ for 1.5h and then naturally cooled to room temperature to obtain the solidified powder. S7: Add the S6 solidified powder to the granulation mixer, and spray 11.3g of silica sol and deionized water while mixing to make the moisture content of the wet material reach 25%. Mix the wet material to make it uniform and spherical. Then continuously feed it into the granulation pan with a granulation pan angle of 50° and a rotation speed of 18rpm to control the particle size of the finished product to 1-3mm. First, solidify it at 60℃ for 2.5h, and then dry it at 105℃ for 8h to make the moisture content of the finished product ≤8% to obtain mineral functional core particles. S8: Prepare a 1.5wt% sodium alginate solution with deionized water and stir to dissolve; add trehalose to make the concentration 2wt%; after the solution cools to room temperature, add Bacillus spore powder and gently stir until homogeneous to obtain 5×10⁻⁶ spores. 7 CFU / mL spore coating solution; S9: Place the mineral functional core particles from step S7 into a fluidized bed and spray them with the spore coating solution from step S8. The fluidized bed inlet air temperature is 30℃, the atomization pressure is 0.2MPa, the coating solution spraying flow rate is 25mL / min, and the target coating weight gain is 10wt%. Soak the wet particles in a 3wt% CaCl2 solution for 15min to crosslink the sodium alginate outer layer into a film. Remove and drain the particles, and vacuum dry them at 25℃ for 20h to obtain in-situ repair particles.

[0014] Example 2: A sediment remediation particle, comprising the following raw materials: zeolite powder, volcanic rock powder, bentonite, silica sol, precursor of loaded functional components, and Bacillus spore powder; The particle size of the zeolite powder and volcanic rock powder is 200 mesh; The effective viable count of the Bacillus spore powder is 1×10⁻⁶. 10 CFU / g; The preparation of the in-situ remediation particles for sediment environments specifically includes the following steps: S1: Weigh out zeolite powder, volcanic rock powder and bentonite according to the proportion, put them into a mixer and dry mix them to obtain a uniform mineral mixture powder; S2: Add the S1 mixed powder to a 0.5 mol / L HCl solution, stir at room temperature for 60 min, filter, and wash with deionized water until the pH of the filtrate is 6.5; dry at 100℃ for 4 h to obtain acid-activated mineral powder; S3: Place the S2 acid-activated mineral powder in a muffle furnace at 500℃ for 3 hours and let it cool naturally to room temperature to obtain mineral carrier powder; S4: Prepare a mixed solution of 0.5 mol / L FeCl3 and 0.05 mol / L Mn(NO3)2 with deionized water to obtain metal salt solution I; add S3 mineral carrier powder to metal salt solution I and stir at 50℃ for 50 min; adjust the pH to 8.3 by adding 2 mol / L NaOH dropwise, and continue stirring for 40 min; let stand for 3 h for aging, filter, wash with deionized water until the conductivity of the filtrate is ≤50µS / cm and the pH is neutral; dry at 80℃ for 4 h to obtain Fe / Mn supported powder; S5: Prepare a mixed solution of 0.3 mol / L MgCl2 and 0.3 mol / L CaCl2 with deionized water to obtain metal salt solution II; add the Fe / Mn supported powder from S4 to metal salt solution II and stir at 50℃ for 60 min; adjust the pH to 9.3 with 1 mol / L Na2CO3 solution, continue stirring for 40 min, let stand for 2 h to age, filter, wash with deionized water until the pH of the filtrate is neutral, and dry at 80℃ for 4 h to obtain Fe / Mn / Mg / Ca co-supported powder; S6: The S5 Fe / Mn / Mg / Ca co-loaded powder was calcined in air at 320℃ for 2 hours and then naturally cooled to room temperature to obtain the solidified powder. S7: Add the S6 solidified powder to the granulation mixer, and spray 5.5g of silica sol and deionized water while mixing to make the moisture content of the wet material reach 20%. Mix the wet material to make it uniform and spherical. Then continuously feed it into the granulation pan with a granulation pan angle of 60° and a rotation speed of 15rpm to control the particle size of the finished product to 1-3mm. First, solidify it at 60℃ for 2h, and then dry it at 105℃ for 6h to make the moisture content of the finished product ≤8% to obtain mineral functional core particles. S8: Prepare a 1wt% sodium alginate solution with deionized water and stir to dissolve; add trehalose to bring the concentration to 1wt%; after the solution cools to room temperature, add Bacillus spore powder and gently stir until homogeneous to obtain 1×10⁻⁶ spores. 7 CFU / mL spore coating solution; S9: Place the mineral functional core particles from step S7 into a fluidized bed and spray them with the spore coating solution from step S8. The fluidized bed inlet air temperature is 25℃, the atomization pressure is 0.1MPa, the coating solution spraying flow rate is 15mL / min, and the target coating weight gain is 8wt%. Soak the wet particles in a 2wt% CaCl2 solution for 10min to crosslink the sodium alginate outer layer into a film. Remove and drain the particles, and vacuum dry them at 20℃ for 24h to obtain in-situ repair particles.

[0015] Example 3: A sediment remediation particle, comprising the following raw materials: zeolite powder, volcanic rock powder, bentonite, silica sol, precursor of loaded functional components, and Bacillus spore powder; The particle size of the zeolite powder and volcanic rock powder is 100 mesh; The effective viable count of the Bacillus spore powder is 1×10⁻⁶. 9 CFU / g; The preparation of the in-situ remediation particles for sediment environments specifically includes the following steps: S1: Weigh out zeolite powder, volcanic rock powder and bentonite according to the proportion, put them into a mixer and dry mix them to obtain a uniform mineral mixture powder; S2: Add the S1 mixed powder to a 0.5 mol / L HCl solution, stir at room temperature for 60 min, filter, and wash with deionized water until the pH of the filtrate is 7; dry at 110℃ for 8 h to obtain acid-activated mineral powder; S3: Place the S2 acid-activated mineral powder in a muffle furnace at 580℃ for 1 hour and cool it naturally to room temperature to obtain mineral carrier powder; S4: Prepare a mixed solution of 0.8 mol / L Fe(NO3)3 and 0.1 mol / L MnSO4 with deionized water to obtain metal salt solution I; add S3 mineral carrier powder to metal salt solution I and stir at 70℃ for 80 min; adjust the pH to 8.7 by adding 2 mol / L NaOH dropwise and continue stirring for 80 min; let stand for 5 h for aging, filter, wash with deionized water until the conductivity of the filtrate is ≤50µS / cm and the pH is neutral; dry at 80℃ for 8 h to obtain Fe / Mn supported powder; S5: Prepare a mixed solution of 0.5 mol / L MgSO4 and 1 mol / L Ca(OH)2 with deionized water to obtain metal salt solution II; add the Fe / Mn supported powder from S4 to metal salt solution II and stir at 50℃ for 90 min; adjust the pH to 9.7 with 1 mol / L Na2CO3 solution, continue stirring for 80 min, let stand for 4 h for aging, filter, wash with deionized water until the pH of the filtrate is neutral, and dry at 80℃ for 8 h to obtain Fe / Mn / Mg / Ca co-supported powder; S6: The S5 Fe / Mn / Mg / Ca co-loaded powder was calcined in air at 380℃ for 1 hour and then naturally cooled to room temperature to obtain the solidified powder. S7: Add the S6 solidified powder to the granulation mixer, and spray 17.8g of silica sol and deionized water while mixing to make the moisture content of the wet material reach 30%. Mix the wet material to make it uniform and spherical. Then continuously feed it into the granulation pan with a granulation pan angle of 60° and a rotation speed of 20rpm to control the particle size of the finished product to 1-3mm. First, solidify it at 60℃ for 3h, and then dry it at 105℃ for 10h to make the moisture content of the finished product ≤8% to obtain mineral functional core particles. S8: Prepare a 2wt% sodium alginate solution with deionized water and stir to dissolve; add trehalose to make the concentration 3wt%; after the solution cools to room temperature, add Bacillus spore powder and stir gently until homogeneous to obtain 1×10⁻⁶ spores. 8 CFU / mL spore coating solution; S9: Place the mineral functional core particles from step S7 into a fluidized bed and spray them with the spore coating solution from step S8. The fluidized bed inlet air temperature is 35℃, the outlet air temperature is 30℃, the atomization pressure is 0.25MPa, the coating solution spraying flow rate is 30mL / min, and the target coating weight gain is 12wt%. Soak the wet particles in a 4wt% CaCl2 solution for 20min to crosslink the sodium alginate outer layer into a film. Remove and drain the particles, and vacuum dry them at 30℃ for 16h to obtain in-situ repair particles.

[0016] Comparative Example 1: In Comparative Example 1, no iron, manganese, magnesium, or calcium sources were added for loading and deposition. Instead, the activated mineral carrier powder was directly subjected to S7 granulation and nucleation. The remaining steps and parameters were the same as in Example 1.

[0017] Comparative Example 2: No Bacillus spore powder was added in Comparative Example 2. In S9, a sodium alginate-trehalose solution without spores was sprayed and then CaCl2 crosslinked to form a film, followed by the same low-temperature drying. The remaining steps and parameters were the same as in Example 1.

[0018] Comparative Example 3: In Comparative Example 3, Bacillus spore powder was directly added to the wet material of S7 granulation; the remaining steps and parameters were the same as in Example 1.

[0019] Comparative Example 4: In Comparative Example 4, CaCl2 crosslinking was not performed, and deionized water soaking of equal duration was used instead of crosslinking soaking; the remaining steps and parameters were consistent with those in Example 1.

[0020] Comparative Example 5: Acid activation and calcination activation were not performed in Comparative Example 5, i.e., S2 and S3 were omitted; the remaining steps and parameters were the same as in Example 1.

[0021] Mechanical strength test: The compressive strength and breakage rate (15N constant load for breaking) of the sample particles of Examples 1-3 and Comparative Examples 1-5 were measured with reference to GB / T 44750-2024, and the coefficient of variation was calculated. The results are shown in Table 1 below.

[0022] Table 1. Mechanical strength test results of in-situ remediation particles in the examples and comparative examples

[0023] Based on the results in Table 1, the overall mechanical properties of the example group are significantly better than those of the comparative group. Example 1 shows the best performance, while Examples 2 and 3 show a slight decrease but still maintain high strength and low dispersion. This indicates that the continuous skeleton structure formed by activation-loading-curing and inorganic cementation granulation in this invention can effectively reduce internal defects and improve particle load-bearing capacity. In the comparative examples, although Comparative Example 2 eliminated the spores, it retained the activation, loading, curing, and granulation skeleton, so the compressive strength did not drop sharply. However, due to the lack of surface defect passivation and stress dispersion caused by the lack of a biological coating layer, it showed lower strength and stability than the examples and a higher breakage rate. After eliminating the loading deposition in Comparative Example 1, the particles can still be formed by silica sol and clay cementation, but the inorganic densification and interface bridging formed by deposition-curing are insufficient, resulting in decreased strength, increased CV, and increased breakage rate. Comparative Examples 3 and 4 correspond to the failure to achieve the post-sclerotium shell structure and the failure to form Ca, respectively. 2+ In cross-linked films, defects on the particle surface and inside are more likely to accumulate, and stress concentration is more pronounced, resulting in higher dispersion and breakage rate. In Comparative Example 5, omitting the activation step leads to insufficient carrier pore structure and surface hydroxyl sites, weakening the effective binding of subsequent loading and cementation. This makes it easier for weak areas to form inside the particles, resulting in the lowest compressive strength and the highest breakage rate. Static release test: Samples: blank control (no particles added), Example 1, Comparative Examples 1-5; Take a 1L container and add 300g of wet bottom sediment (remove stones, shells and large particles, mix thoroughly and pass through a 2mm sieve), slowly add 700mL of top water along the container wall, avoiding stirring the bottom sediment, let it stand at 25℃ for 24h as the equilibrium period, add particles based on the dry basis of the bottom sediment (i.e., 2g / 100g dry sediment); if the dry basis of the bottom sediment is unknown, the moisture content can be measured first and converted accordingly; Spread each test sample evenly on the surface of the bottom sediment, allowing the particles to settle naturally and cover the interface area, incubate at 25±1℃ in the dark, and take samples on days 0, 1, 3, 7, 14 and 28 respectively, each time taking 10mL of top water from about 2cm above the mud-water interface, and immediately add an equal volume of top water from the same batch after sampling to maintain a constant volume, PO4 3- With NH4 + -N samples were filtered through a 0.45 μm filter after sampling; sulfide samples (with S...) 2- Immediately after sampling, zinc acetate was added for fixation, and NH4 was determined using the indophenol blue method. + Ammonium molybdate spectrophotometric determination of PO4 3- The methylene blue method for determining sulfides yielded the following test results: Figure 1 , Figure 2 and Figure 3 As shown.

[0024] based on Figure 1-3 Results analysis showed that in the blank group, NH4 increased with prolonged culture time. + PO4 3-Both dissolved sulfides and nitrogen oxides showed a continuous upward trend, reflecting the continuous release and enhanced reductive properties of sediment under static conditions. In Example 1, after addition, all indicators rapidly decreased and remained at low levels for a long period, indicating that the adsorption / ion exchange of mineral functional cores and the fixation / passivation of Fe / Mn and Mg / Ca sites provided pre-purification and buffering. Simultaneously, the core-shell cross-linked film enhanced spore stability and sustained action, ensuring the inhibitory effect did not diminish within 28 days. In Comparative Example 2, although spores were eliminated, the activated, loaded, solidified, and granulated framework was still retained, resulting in significant inhibition in the early and middle stages. However, the sustained inhibition of nitrogen, phosphorus, and sulfides in the later stages was slightly weaker than in Example 1. Comparative Example 1, even after removing the loading sites, still showed contributions from mineral adsorption and ion exchange, superior to the blank, but its control over phosphorus and sulfides was significantly insufficient. Comparative Examples 3 (simultaneous addition) and 4 (without cross-linking film formation) showed a certain decrease in the early stages, but due to the lack of a stable core-shell immobilization structure, spores were easily inactivated or lost, leading to a rebound in the middle and later stages, especially a significant rebound in sulfides. Comparative Example 5, by omitting activation, resulted in insufficient pore structure and interface sites, leading to a decrease in loading and fixation efficiency. It exhibited the weakest overall inhibition and the largest increase in release in the later stage.

[0025] Rinsing Test: Samples: Example 1, Comparative Examples 2-4; Weigh 0.5g of sample particles into a sterile centrifuge tube, add 50mL of sterile PBS, vortex for 2min to fully elute the spores on the particle surface and in the coating layer into the liquid phase, perform a 10-fold serial dilution of the eluent, plate it, incubate for 24h, and count the viable bacteria count C0 (CFU / g dry weight of particles) before rinsing; Add 200mL of PBS and 2g of sample particles to each conical flask, seal and place in a shaker at 25℃, rinse at 150rpm for 2h. After rinsing, remove the particles with a sterile sieve, drain the surface liquid, weigh 0.5g of sample particles again, and obtain the viable bacteria count C1 (CFU / g dry weight of particles) after rinsing using the same elution method as above. Calculate the viable bacteria retention rate (%) = C1 / C0 × 100%, and the results are as follows. Figure 4 As shown.

[0026] based on Figure 4 As a result, Example 1 had the highest retention rate, and in the static release test, Example 1 maintained the lowest NH4 level for 28 days. + / PO4 3-The consistency with sulfides indicates that the outer cross-linked membrane effectively resists erosion and loss, ensuring the continuous recovery and long-term effect of spores. Comparative Example 4 showed a moderate retention rate, consistent with the rebound observed in the later stages of the static release test, indicating that the uncross-linked membrane layer is more prone to detachment under hydrodynamic conditions, making it difficult to maintain the biological effect. Comparative Example 3 showed the lowest retention rate, consistent with one of the most significant rebounds in the later stages of its static release test, indicating that simultaneous mixing and granulation makes it difficult to form a stable immobilized structure, resulting in a significant decrease in the effective bacterial count after erosion. Comparative Example 2, without added strains, was considered negative: consistent with its trend of performing relatively well but weaker than Example 1 in the static release test.

[0027] Continuous action test: Samples: blank control (no particles added), Example 1, Comparative Examples 1-5. Take a 1L container and add 300g of wet bottom mud (remove stones, shells and large particles, mix thoroughly and pass through a 2mm sieve). Slowly add 700mL of top water along the container wall, avoiding stirring the bottom mud. Let it stand at 25℃ for 24h as the equilibration period. Add particles based on the dry basis of the bottom mud (i.e., 2g / 100g dry mud). If the dry basis of the bottom mud is unknown, the moisture content can be measured first and then converted. Spread each test sample evenly on the surface of the bottom mud, allowing the particles to settle naturally and cover the interface area. Incubate at 25±1℃ in the dark. Take 10mL of top water from about 2cm above the mud-water interface each time to measure PO4. 3- Then, simultaneously remove 100 mL of topsoil from each bottle and add 100 mL of fresh topsoil from the same batch. Add 5 mL of 100 mg / L KH2PO4 standard solution to each bottle. Take samples on days 7, 14, 28, and 42, and record the PO4 content in the topsoil. 3- Changes in viable bacterial count and retention rate of particles (to determine the viable bacterial count of particles at each time point, parallel bottles corresponding to the sampling time points were set up; at 7 days, 14 days, 28 days, and 42 days, all particles from the corresponding parallel bottles were taken out, collected with a sterile sieve, and washed once with sterile PBS. 0.5g of particles were weighed and added to 50mL of sterile PBS, vortexed for 2min to elute spores, serially diluted 10-fold, plated, and incubated for 24h for counting to obtain the viable bacterial count C of particles at each time point). t and with C t The viable cell retention rate is calculated as C0 × 100%, where C0 is determined by the flushing test method. The test results are as follows: Figure 5 and Figure 6 As shown.

[0028] based on Figure 5-6 Results analysis showed that Example 1 maintained a high viable bacterial retention rate even after 42 days, with PO4... 3-The low level of phosphorus retention, with no significant rebound, reflects the stability of the fixation of loading sites and the long-term synergistic effect of the biolayer. Although Comparative Example 2 was sterile, phosphorus fixation was still stable at sites such as Mg / Ca, resulting in good phosphorus control in the early and middle stages. However, lacking the continuous regulation of interfacial state and organic matter transformation by the biolayer, a slight rebound occurred in the later stages, indicating that the biolayer contributes to stability under long-term continuous shocks. The rapid decline in viable cell retention rate in Comparative Example 3 / 4 was related to its PO4 content. 3- The significant rebound between 28 and 42 days confirms that the posterior sclerotium shell structure is consistent with Ca. 2+ Cross-linking film formation is key to achieving long-term continuous action. Comparative Example 5 suffers from low core-pore structure and site efficiency, and weak buffering capacity due to activation deficiency; PO4... 3- The levels continued to rise and approached zero, while the viable bacteria declined even faster, indicating that activation was a fundamental step. In Comparative Example 1, after removing the loading sites, phosphorus control mainly relied on mineral adsorption, PO4... 3- The levels were significantly higher than those in Example 1 and Comparative Example 2; at the same time, due to the lack of a pre-buffer for sulfide / reducing inhibition, the viable bacteria decayed faster, further leading to insufficient long-term phosphorus control stability.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A type of in-situ remediation particle for sediment environments, characterized in that, Its composition includes the following raw materials: zeolite powder, volcanic rock powder, bentonite, silica sol, precursor of loaded functional components, and Bacillus spore powder; The precursor for the loaded functional component is composed of an iron source, a manganese source, a magnesium source, and a calcium source; The particle size of the zeolite powder and volcanic rock powder is 100-200 mesh.

2. The in-situ remediation particles for sediment environments according to claim 1, characterized in that, The iron source is selected from any one of FeCl3 and Fe(NO3)3; the manganese source is selected from any one of MnSO4 and Mn(NO3)2; the magnesium source is selected from any one of MgCl2, MgSO4 and Mg(NO3)2; and the calcium source is selected from any one of CaCl2, Ca(NO3)2, Ca(OH)2 and light CaCO3.

3. The in-situ remediation particles for sediment environments according to claim 1, characterized in that, The effective viable count of the Bacillus spore powder is 1×10⁻⁶. 9 ~10 10 CFU / g.

4. A method for preparing in-situ remediation particles for sediment environments according to any one of claims 1-3, characterized in that, Specifically, the following steps are included: S1: Weigh out zeolite powder, volcanic rock powder and bentonite according to the proportion, put them into a mixer and dry mix them to obtain a uniform mineral mixture powder; S2: Add the S1 mixed powder to an HCl solution, stir at room temperature, filter, wash with deionized water, and dry to obtain acid-activated mineral powder; S3: Place the S2 acid-activated mineral powder in a muffle furnace for calcination and allow it to cool naturally to room temperature to obtain mineral carrier powder; S4: Prepare a mixed solution of iron and manganese sources with deionized water to obtain metal salt solution I; add S3 mineral carrier powder to metal salt solution I, heat and stir; adjust the pH with NaOH dropwise, continue stirring; let stand for aging, filter, wash with deionized water; dry to obtain Fe / Mn supported powder; S5: Prepare a mixed solution of magnesium source and calcium source with deionized water to obtain metal salt solution II; add S4 Fe / Mn supported powder to metal salt solution II, heat and stir; adjust pH with 1 mol / L Na2CO3 solution, continue stirring, let stand for aging, filter, wash with deionized water until the pH of the filtrate is neutral, dry, and obtain Fe / Mn / Mg / Ca co-supported powder. S6: The S5 Fe / Mn / Mg / Ca co-loaded powder is calcined in air and then naturally cooled to room temperature to obtain a solidified powder. S7: Add the S6 solidified powder to the granulation mixer, and spray silica sol and deionized water while mixing. Knead the mixture to make the wet material uniform and spherical. Then continuously feed it into the granulation tray to control the particle size of the finished product. First solidify, then dry to obtain mineral functional core particles. S8: Prepare sodium alginate solution with deionized water and stir to dissolve; add trehalose; after the solution cools to room temperature, add Bacillus spore powder and stir gently until homogeneous to obtain spore coating solution; S9: Place the mineral functional core particles from step S7 into a fluidized bed, spray with the spore coating solution from step S8, immerse the wet particles in a CaCl2 solution to crosslink the sodium alginate outer layer into a film, remove and drain, vacuum dry to obtain in-situ repair particles.

5. The method for preparing in-situ remediation particles for sediment environments according to claim 4, characterized in that, In step S1, the mass ratio of zeolite powder, volcanic rock powder and bentonite is 10:6-7:0.6-0.

8.

6. The method for preparing in-situ remediation particles for sediment environments according to claim 4, characterized in that, In step S2, the solid-liquid ratio of the mixed powder and the HCl solution is 1g:6-10mL.

7. The method for preparing in-situ remediation particles for sediment environments according to claim 4, characterized in that, In step S3, the calcination temperature is 500-580℃ and the time is 1-3 hours.

8. The method for preparing in-situ remediation particles for sediment environments according to claim 4, characterized in that, In step S4, the solid-liquid ratio of the mineral carrier powder to metal salt solution I is 1g:8-10mL; in step S5, the solid-liquid ratio of the Fe / Mn supported powder to metal salt solution II is 1g:8-12mL.

9. The method for preparing in-situ remediation particles for sediment environments according to claim 4, characterized in that, In step S7, the silica sol contains 30 wt% SiO2; and the amount of silica sol added is 1 to 3 wt% of the mass of the solidified powder in step S6, calculated as SiO2; the granulation disk angle is 40 to 60°, and the rotation speed is 15 to 20 rpm.

10. The method for preparing in-situ remediation particles for sediment environments according to claim 4, characterized in that, In step S8, the activity of Bacillus in the spore coating solution is 1×10⁻⁶. 7 ~10 8 CFU / mL; The spraying parameters are: fluidized bed inlet air temperature 25-35℃, atomizing air pressure 0.1-0.25MPa, coating liquid spraying flow rate 15-30mL / min, and target coating weight gain 8-12wt%.

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