Biochar / double-gel composite microbial remediation agent particles as well as preparation method and application of biochar / double-gel composite microbial remediation agent particles

Abstract

The invention discloses biochar / double-gel composite microbial remediation agent particles which are prepared from biochar powder, basophilic microorganisms, magnesium lithium silicate inorganic gel, sodium alginate hydrogel and calcium salt. Accordingly, a corresponding preparation method is also established, namely, the biochar powder and the basophilic microbial spore culture solution are mixed, compounded with the magnesium lithium silicate inorganic gel and the sodium alginate hydrogel and then crosslinked with the calcium salt solution, and the microspherical microbial remediation agent particles are obtained. The method is easy and convenient to operate, high in cost effectiveness, environmentally friendly and suitable for industrial large-scale production. The obtained repairing agent is good in particle sphericity degree, small in particle strength deviation, good in biocompatibility and long-term stability and good in self-repairing effect on concrete cracks.

Description

Technical Field

[0001] The invention belongs to the field of solid waste resource utilization and concrete materials science, and in particular relates to a biochar / double gel composite microbial repair agent particle and a preparation method and application thereof. Background Art

[0002] In the context of global environmental protection and sustainable development, low-carbon emission reduction has become a key issue in construction and materials science. As one of the most widely used materials in modern construction, concrete produces a large amount of carbon emissions during its production and use, which puts tremendous pressure on the environment. Improving the service life of concrete structures is an effective way to save energy and reduce emissions in the construction industry, but once concrete cracks, it is difficult to repair it in time, resulting in accelerated structural deterioration. In addition, traditional repair materials have shortcomings in durability, biocompatibility and environmental friendliness. Therefore, the development of innovative composite repair materials has become an important task.

[0003] Lithium magnesium silicate inorganic gel and sodium alginate hydrogel are widely used in biomedicine and materials science due to their good adsorption potential, surface charge characteristics and biocompatibility. Biochar, as a material with high porosity and high specific surface area, is considered to be an ideal microbial carrier due to its good adsorption performance and biocompatibility. Converting agricultural waste into high-value-added biochar materials through carbonization not only realizes waste utilization, but also reduces greenhouse gas emissions.

[0004] Therefore, developing a low-carbon and environmentally friendly building material with self-repairing function based on a biochar / double gel composite system is of great significance for improving the durability and service life of concrete and reducing the carbon footprint. Summary of the invention

[0005] The present invention aims to solve the deficiencies of the prior art microbial repair agents in terms of biocompatibility and long-term stability. To this end, the present invention provides a biochar / double gel composite microbial repair agent particle and a preparation method and application thereof. The repair agent particle has excellent biocompatibility and long-term stability, and can effectively repair concrete cracks, showing a good self-repairing effect.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The biochar / double-gel composite microbial remediation agent particles are made of biochar powder, alkaliphilic microorganisms, lithium magnesium silicate inorganic gel, sodium alginate hydrogel and calcium salt as raw materials.

[0008] The biochar powder is obtained by carbonizing plant fibers, and the plant fibers are hemp fibers, wood waste, and fruit peel waste; the alkaliphilic microorganisms are Bacillus pasteurianus, Bacillus cohnii, Bacillus pseudofirmus, and Bacillus alkaliphilus; and the calcium salts are calcium chloride, calcium acetate, calcium nitrate, and calcium lactate.

[0009] The preparation method of the above-mentioned microbial remediation agent particles is to mix biochar powder with alkaliphilic microbial spore culture solution, and compound it with lithium magnesium silicate inorganic gel and sodium alginate hydrogel, and then cross-link it with calcium salt solution to obtain microspherical microbial remediation agent particles.

[0010] The above preparation method comprises the following steps:

[0011] (1) placing the crushed plant fiber in an oven for drying, cooling to room temperature, and then placing it in a carbonization furnace for carbonization treatment under the protection of an inert gas, and grinding it into powder after cooling in the furnace to obtain biochar powder;

[0012] (2) inoculating an alkaliphilic microbial strain into an alkaline medium, adding a spore conversion promoting agent to the alkaline medium, and obtaining a microbial spore culture solution after shaking culture;

[0013] (3) preparing sodium alginate hydrogel and lithium magnesium silicate inorganic gel respectively under constant temperature water bath conditions, and adding nutrients to the sodium alginate hydrogel;

[0014] (4) fully mixing the microbial spore culture solution of step (2) and the biochar powder of step (1) to obtain a bacterial suspension, and then adjusting the pH value of the bacterial suspension with a nitric acid solution;

[0015] (5) uniformly mixing the bacterial suspension of step (4) and the lithium magnesium silicate inorganic gel of step (3), and allowing them to stand for rehydration to obtain a gel suspension; uniformly mixing the gel suspension with the sodium alginate hydrogel of step (3) to obtain a composite gel suspension;

[0016] (6) Using a micro-syringe pump or a peristaltic pump, dropwise add the composite gel suspension of step (5) into the calcium salt solution, filter out the repair agent particles after sufficient cross-linking, place the repair agent particles in an ultra-clean workbench to air dry, and then place them in an oven to dry.

[0017] In step (1), the drying temperature is 100°C to 110°C, the carbonization temperature is 400°C to 700°C, the carbonization time is 0.5h to 2h, and the heating rate is 2°C / min to 10°C / min; the particle size range of the biochar powder is 0.5μm to 300μm.

[0018] In step (2), the inoculation amount of the alkaliphilic microbial strain is 1% of the volume of the alkaline culture medium, the pH value of the alkaline culture medium is 9-10, the spore conversion promoting agent mainly comprises anhydrous manganese sulfate, the addition amount thereof is 0.16 g / L-0.2 g / L, the culture is carried out under constant temperature shaking for 48 h-96 h, the temperature is 25° C.-37° C., and the shaking rate is 160 r / min-180 r / min.

[0019] In step (3), the water bath temperature is 32° C. to 42° C., the mass volume concentration of the sodium alginate hydrogel is 1% to 2%, the mass volume concentration of the lithium magnesium silicate inorganic gel is 2% to 2.5%, the nutrient is one of casein peptone, soybean meal peptone, yeast extract powder, beef extract powder, peptone, urea, sucrose, and inosine, or a combination thereof, and the mass volume ratio of the nutrient to the sodium alginate hydrogel is 1 g:20 mL to 30 mL.

[0020] In step (4), the mass volume ratio of biochar powder to microbial spore culture solution is 1 g: 2 mL to 3 mL, the concentration of nitric acid solution is 0.8 mol / L to 1 mol / L, and the pH value of the bacterial suspension is adjusted to 7 to 8.

[0021] In step (5), the volume ratio of the bacteria-carrying suspension to the lithium magnesium silicate inorganic gel is 1:0.5-2, and the volume ratio of the gel suspension to the sodium alginate hydrogel is 1:0.5-2.

[0022] In step (6): the mass concentration of the calcium salt solution is 1.8-2.5%.

[0023] Application of the above-mentioned microbial remediation agent particles or the microbial remediation agent particles obtained by the preparation method in concrete repair.

[0024] In response to the problems existing in current concrete repair materials, the inventors have developed a biochar / double gel composite microbial repair agent particle, which is made of biochar powder, alkaliphilic microorganisms, lithium magnesium silicate inorganic gel, sodium alginate hydrogel and calcium salt as raw materials. Based on this, a corresponding preparation method has also been established, that is, by mixing biochar powder with alkaliphilic microbial spore culture fluid, and compounding with lithium magnesium silicate inorganic gel and sodium alginate hydrogel, and then cross-linking with calcium salt solution, microspherical microbial repair agent particles are obtained. This method is not only simple to operate and cost-effective, but also environmentally friendly and suitable for industrial-scale production. The obtained repair agent particles have good sphericity and small particle strength deviation, and at the same time have good biocompatibility and long-term stability, and have a good self-repair effect on concrete cracks.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] (1) The present invention uses biochar as a carrier for microorganisms and uses its porous structure to create suitable growth conditions for microorganisms, which is conducive to improving the survival rate of microorganisms and thus enhancing the self-repairing ability of concrete. In addition, the high porosity of biochar gives it excellent adsorption capacity, which can effectively capture harmful media such as chloride ions, sulfate ions and carbon dioxide in the environment, preventing these media from penetrating into the interior of the concrete, significantly improving the durability of the concrete structure and extending its service life.

[0027] (2) The present invention can flexibly add a variety of functional auxiliary materials during the preparation process, which can effectively improve the physical and chemical properties of the repair agent and greatly enhance the adaptability and overall performance of the repair agent to diverse application environments.

[0028] (3) The preparation method of the present invention has the characteristics of simple operation and easy control of process conditions, which ensures that the structure and performance of the prepared repair agent particles are stable and reliable. The method also has the advantage of being suitable for industrial large-scale production, with high production efficiency, which can effectively reduce manufacturing costs and thus maximize economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 These are actual pictures of the repair agent particles of the embodiments and comparative examples, in which: a is embodiment 1, b is embodiment 2, and c is comparative example.

[0030] Figure 2 It is a comparison chart of the average value and standard deviation of the single particle strength of the repair agent particles of the embodiment and the comparative example.

[0031] Figure 3 It is a comparison chart of the compressive strength of the test pieces of the embodiment, comparative example and control group at different ages.

[0032] Figure 4 It is a comparison chart of the compressive strength recovery rate of the test pieces in the embodiment, comparative example and control group after 35 days of repair.

[0033] Figure 5 The following are the crack repair effect diagrams of the embodiment and comparative example specimens. DETAILED DESCRIPTION

[0034] 1. Implementation

[0035] Example 1

[0036] (1) The crushed bagasse fiber was placed in an oven at 105°C for 3 hours, cooled to room temperature, and then placed in a carbonization furnace. The temperature was raised from room temperature to 500°C at a heating rate of 3°C / min under inert gas protection. The fiber was carbonized at this temperature for 45 minutes, cooled to room temperature with the furnace, and ground and sieved to obtain biochar. The particle size of the biochar was less than 275 μm.

[0037] (2) Sporosarcina pasteurii ATCC 11859 was inoculated into an alkaline medium at a volume inoculation rate of 1%. The alkaline medium contained the following components: 1000 parts of deionized water, 3 parts of casein peptone, 1 part of soybean meal peptone, 4 parts of urea, 0.02 parts of potassium dihydrogen phosphate, 0.18 parts of anhydrous manganese sulfate, 4.2 parts of sodium carbonate, and 5.3 parts of sodium bicarbonate. The alkaline medium was placed in a constant temperature shaking incubator at a temperature of 30°C and a shaking rate of 180 r / min for 96 h. The concentration of the obtained microbial spore culture solution was 4×10 8 CFU / mL.

[0038] (3) Sodium alginate is added to sterilized deionized water to prepare a sodium alginate hydrogel with a mass volume concentration of 2%, and a lithium magnesium silicate inorganic gel with a mass volume concentration of 2.5% is prepared in this way. A high-speed disperser is used for mixing during the gel preparation process to achieve uniform dispersion of the sodium alginate hydrogel and the lithium magnesium silicate inorganic gel. Nutrients are added to the sodium alginate hydrogel, and the ratio of the sodium alginate hydrogel to the nutrients is: 1000 parts of sodium alginate hydrogel, 12 parts of casein peptone, 4 parts of soybean meal peptone, 20 parts of urea, 3 parts of yeast extract powder, and 8 parts of inosine.

[0039] (4) During the gel preparation process, the biochar powder and the microbial spore culture solution were fully mixed at a mass volume ratio of 1 g:2 mL to obtain a bacterial suspension, and then the pH value of the bacterial suspension was adjusted to 7-7.5 with a 1 mol / L nitric acid solution;

[0040] (5) The bacterial suspension was mixed with the inorganic gel of lithium magnesium silicate in a volume ratio of 2:1, and allowed to stand for rehydration to obtain a gel suspension; the gel suspension was mixed with the sodium alginate hydrogel in a volume ratio of 2:1 to obtain a composite gel suspension for standby use;

[0041] (6) Calcium nitrate tetrahydrate was added to sterilized deionized water to prepare a calcium nitrate solution with a mass concentration of 2%. The composite gel suspension was dripped into the calcium nitrate solution drop by drop using a peristaltic pump to form a microsphere repair agent. After sufficient cross-linking, the repair agent particles were filtered out and placed in an ultra-clean workbench to air-dry for 6 hours. Subsequently, the air-dried repair agent particles were placed in an oven at 50°C and dried for 18 hours to finally obtain a microbial repair agent immobilized with Bacillus pasteurianus.

[0042] Example 2

[0043] (1) The crushed bagasse fiber was placed in an oven at 105°C for 3 hours, cooled to room temperature, and then placed in a carbonization furnace. The temperature was raised from room temperature to 500°C at a heating rate of 3°C / min under inert gas protection. The fiber was carbonized at this temperature for 45 minutes, cooled to room temperature with the furnace, and ground and sieved to obtain biochar. The particle size of the biochar was less than 275 μm.

[0044] (2) Bacillus cohnii DSM 6307 was inoculated into an alkaline medium at a volume inoculation rate of 1%, wherein the alkaline medium comprises: 1000 parts of deionized water, 3 parts of sucrose, 3 parts of yeast extract powder, 0.15 parts of anhydrous calcium chloride, 0.02 parts of potassium dihydrogen phosphate, 0.18 parts of anhydrous manganese sulfate, 4.2 parts of sodium carbonate, and 5.3 parts of sodium bicarbonate. The alkaline medium was placed in a constant temperature shaking incubator at a temperature of 30°C and a shaking rate of 180 r / min for 96 hours, and the concentration of the obtained microbial spore culture solution was 2×10 8 CFU / mL;

[0045] (3) Sodium alginate is added to sterilized deionized water to prepare a sodium alginate hydrogel with a mass volume concentration of 2%, and a lithium magnesium silicate inorganic gel with a mass volume concentration of 2.5% is prepared in this way. A high-speed disperser is used for mixing during the gel preparation process to achieve uniform dispersion of the sodium alginate hydrogel and the lithium magnesium silicate inorganic gel. Nutrients are added to the sodium alginate hydrogel, and the ratio of the sodium alginate hydrogel to the nutrients is: 1000 parts of sodium alginate hydrogel, 3 parts of peptone, 12 parts of sucrose, 12 parts of yeast extract powder, and 8 parts of inosine.

[0046] (4) During the gel preparation process, the biochar powder and the microbial spore culture solution were fully mixed at a mass volume ratio of 1 g:2 mL to obtain a bacterial suspension, and then the pH value of the bacterial suspension was adjusted to 7-7.5 with a 1 mol / L nitric acid solution;

[0047] (5) The bacterial suspension was mixed with the inorganic gel of lithium magnesium silicate in a volume ratio of 2:1, and allowed to stand for rehydration to obtain a gel suspension; the gel suspension was mixed with the sodium alginate hydrogel in a volume ratio of 2:1 to obtain a composite gel suspension for standby use;

[0048] (6) Calcium lactate was added to sterilized deionized water to prepare a calcium lactate solution with a mass concentration of 2%. The composite gel suspension was dripped into the calcium lactate solution drop by drop using a peristaltic pump to form a microsphere repair agent. After sufficient cross-linking, the repair agent particles were filtered out and placed in an ultra-clean workbench for air drying for 6 hours. The air-dried repair agent particles were then placed in an oven at 50°C for drying for 18 hours to finally obtain a microbial repair agent immobilized with Bacillus cohnii.

[0049] 2. Comparison

[0050] (1) The crushed bagasse fiber was placed in an oven at 105°C for 3 hours, cooled to room temperature, and then placed in a carbonization furnace. The temperature was raised from room temperature to 500°C at a heating rate of 3°C / min under inert gas protection. The fiber was carbonized at this temperature for 45 minutes, cooled to room temperature with the furnace, and ground and sieved to obtain biochar. The particle size of the biochar was less than 275 μm.

[0051] (2) Sodium alginate was added to sterilized deionized water to prepare a sodium alginate hydrogel with a mass volume concentration of 2%, and a lithium magnesium silicate inorganic gel with a mass volume concentration of 2.5% was prepared in the same manner. During the gel preparation process, a high-speed disperser was used for mixing to achieve uniform dispersion of the sodium alginate hydrogel and the lithium magnesium silicate inorganic gel.

[0052] (3) During the gel preparation process, the biochar powder was thoroughly mixed with sterilized deionized water at a mass volume ratio of 1 g:2 mL to obtain a biochar suspension;

[0053] (4) The biochar suspension and the lithium magnesium silicate inorganic gel are mixed evenly in a volume ratio of 2:1, and allowed to stand for rehydration to obtain a gel suspension; the gel suspension and the sodium alginate hydrogel are mixed evenly in a volume ratio of 2:1 to obtain a composite gel suspension for standby use;

[0054] (5) Calcium chloride dihydrate was added to sterilized deionized water to prepare a calcium chloride solution with a mass concentration of 2%. The composite gel suspension was dripped into the calcium chloride solution drop by drop using a peristaltic pump to form a microsphere repair agent. After sufficient cross-linking, the repair agent particles were filtered out and placed in an ultra-clean workbench to air-dry for 6 hours. Subsequently, the air-dried repair agent particles were placed in an oven at 50°C for 18 hours to finally obtain bacteria-free repair agent particles.

[0055] This comparative example is based on Example 1. Compared with Example 1, the main differences of this comparative example are: (a) step (2) is not included; (b) in step (3), no nutrients are added to the sodium alginate hydrogel; (c) in step (4), the microbial spore culture solution is replaced with sterilized deionized water; (d) in step (4), nitric acid solution is not used to adjust the pH value of the suspension; (e) in step (6), calcium nitrate tetrahydrate is replaced with calcium chloride dihydrate. The rest is the same as Example 1.

[0056] 3. Evaluation of repair agent performance

[0057] 3.1 Appearance of repair agent particles

[0058] like Figure 1 As shown, the particle size distribution of the repair agent particles obtained in the comparative example and the embodiment of the present invention is concentrated, and both have good particle uniformity.

[0059] 3.2 Properties of repair agent particles

[0060] 100 repair agent particles were randomly selected to test the single particle strength, and the mean and standard deviation of the single particle strength were calculated.

[0061] The average and standard deviation of the single particle strength of Example 1, Example 2 and the comparative example are as follows: Figure 2 shown.

[0062] from Figure 2 It can be seen that the average value of the single particle strength is Example 2>Comparative Example>Example 1, and the standard deviation of the single particle strength is Comparative Example>Example 2>Example 1. The difference in the role of urea and sucrose in the preparation of particles has a significant effect on the mechanical properties and uniformity of the particles. Urea may interact with the carboxyl group in sodium alginate, thereby interfering with the cross-linking process of calcium ions and sodium alginate. This interference may cause the cross-linked network to be not tight enough, thereby reducing the strength of the repair agent particles prepared in Example 1. Although urea may destroy the cross-linked network, its uniform distribution in the particles helps to form a more consistent particle structure. This uniform distribution makes the strength distribution of the repair agent particles prepared in Example 1 more concentrated and the standard deviation is small. Sucrose enhances the strength of the repair agent particles prepared in Example 2 through filling and bonding, but may increase the inhomogeneity of the internal structure of the particles, making the strength distribution of the repair agent particles prepared in Example 2 more dispersed and the standard deviation larger. This shows that adding different excipients will have a significant effect on the mechanical properties of the repair agent. Therefore, selecting suitable excipients and optimizing their addition methods can significantly improve the comprehensive performance of the repair agent and meet the needs of different application scenarios.

[0063] 3.3 Effect of repair agent particles on the mechanical properties of concrete

[0064] In order to verify the influence of the repair agent particles on the mechanical properties of concrete, the repair agent particles obtained in Example 1, Example 2 and the comparative example were subjected to the following experiments:

[0065] The repair agent particles obtained in Example 1, Example 2 and the comparative example are added to the concrete during stirring to replace part of the concrete aggregate to prepare cubic specimens with a size of 100mm×100mm×100mm. At the same time, concrete specimens without the addition of repair agent particles are designed as a control group. The specimens are demolded 24 hours after molding, and the specimens are placed in a standard curing room for curing. The compressive strength of the concrete specimens is measured at a curing age of 3d, 7d, and 28d. At the age of 28d, the concrete specimens are pre-cracked by applying a load equivalent to 80% of their 28d compressive strength, and the specimens are immersed in water for ventilation curing. The water temperature is controlled at (30±1)℃, and the compressive strength of the concrete specimens is measured after 35d of immersion repair. The compressive strength recovery rate is calculated by the following formula:

[0066]

[0067] Where:

[0068] CSR – compressive strength recovery rate;

[0069] F 28 d——28d compressive strength of concrete cube specimen (MPa);

[0070] F 35 d is the compressive strength of the concrete cube specimen after 35 days of repair (MPa).

[0071] The compressive strength of the specimens in Example 1, Example 2, Comparative Example and Control Group at different ages is as follows Figure 3 As shown. Figure 3 It can be seen that the effect of the repair agent particles on the early compressive properties of concrete is relatively limited. In the early stage, the concrete mixed with the repair agent particles showed relatively excellent compressive strength. This may be because the repair agent particles can quickly play a role in the early stage of concrete, promote the partial hydration reaction, and thus improve the early strength. However, with the increase of age, the later strength growth of ordinary concrete is more significant, and its strength can continue to increase and gradually exceed that of concrete mixed with repair agent particles. This shows that although the repair agent particles have a certain effect on improving the compressive properties of concrete in the early stage, their effect on the continuous growth of strength in the later stage is not as good as that of ordinary concrete.

[0072] The compressive strength recovery rates of the specimens in Example 1, Example 2, Comparative Example and Control Group after 35 days of repair are as follows: Figure 4As shown. The compressive strength recovery rates of the specimens in Example 1, Example 2, the comparative example and the control group are all over 100%, and the compressive strength recovery rate is Example 1>Comparative example>Control group>Example 2. During the immersion and ventilation curing process, the penetration of water can prompt the cement particles that are not fully hydrated in the matrix of the specimen to continue to undergo hydration reaction. At the same time, the calcium hydroxide in the matrix will undergo carbonization reaction with carbon dioxide in the air to generate calcium carbonate. Both processes may lead to an increase in the compressive strength of the specimen.

[0073] 3.4 Repair effect of repair agent particles on concrete cracks

[0074] In order to verify the repairing effect of the repair agent particles on concrete cracks, the repair agent particles obtained in Example 1, Example 2 and the comparative example were subjected to the following experiment:

[0075] The repair agent particles obtained in Example 1, Example 2 and the comparative example are added to the concrete during stirring to replace part of the concrete aggregate to prepare cylindrical specimens with a size of φ100mm×200mm. At the same time, concrete specimens without the addition of repair agent particles are designed as a control group. The specimens are demolded 24 hours after molding, and the specimens are placed in a standard curing room for curing. When the curing age is 21d, two specimens with a height of (50±2)mm are cut from the middle of the specimen, and the processed specimens should continue to be placed in a standard curing room for curing. When the curing age is 28d, the specimens are taken out and cracks are created. After 56d of the cracks, the specimens are immersed in water for ventilation curing, and the water temperature is controlled at (30±1)℃. The healing effect of the cracked specimens at multiple repair ages is monitored.

[0076] The crack healing effects of Example 1, Example 2 and Comparative Example specimens are as follows: Figure 5 As shown. Figure 5 It can be seen that as time goes by, the repair product grows from both sides of the crack to the center. At the same dosage, the repair effect of the test pieces of Example 1 and Example 2 is significantly better than that of the comparative test piece. After 35 days of curing, the repair product basically fills the crack, while there is only a small amount of repair product on both sides of the crack of the comparative test piece, which may be related to the incomplete hydration of calcium hydroxide in the concrete matrix.

[0077] The specific proportions of the above-mentioned Example 1, Example 2, Comparative Example and Control Group can be seen in the following Table 1.

[0078] Table 1, Example 1, Example 2, Comparative Example and Control Group Concrete Mix Ratio

[0079]

Claims

1. A biochar / double gel composite microbial remediation agent particle, characterized in that It is made from biochar powder, alkaliphilic microorganisms, lithium magnesium silicate inorganic gel, sodium alginate hydrogel and calcium salt.

2. The microbial remediation agent particles according to claim 1, characterized in that: The biochar powder is obtained by carbonizing plant fibers, and the plant fibers are hemp fibers, wood waste, and fruit peel waste; the alkaliphilic microorganisms are Bacillus pasteurianus, Bacillus cohnii, Bacillus pseudofirmus, and Bacillus alkaliphilus; and the calcium salts are calcium chloride, calcium acetate, calcium nitrate, and calcium lactate.

3. The method for preparing the microbial remediation agent particles according to claim 1, characterized in that: The microspherical microbial remediation agent particles are obtained by mixing biochar powder with alkaliphilic microbial spore culture solution, compounding with lithium magnesium silicate inorganic gel and sodium alginate hydrogel, and then cross-linking with a calcium salt solution.

4. The preparation method according to claim 3, characterized in that The following steps are involved: (1) placing the crushed plant fiber in an oven for drying, cooling to room temperature, and then placing it in a carbonization furnace for carbonization treatment under the protection of an inert gas, and grinding it into powder after cooling in the furnace to obtain biochar powder; (2) inoculating an alkaliphilic microbial strain into an alkaline medium, adding a spore conversion promoting agent to the alkaline medium, and obtaining a microbial spore culture solution after shaking culture; (3) preparing sodium alginate hydrogel and lithium magnesium silicate inorganic gel respectively under constant temperature water bath conditions, and adding nutrients to the sodium alginate hydrogel; (4) fully mixing the microbial spore culture solution of step (2) with the biochar powder of step (1) to obtain a bacterial suspension, and then adjusting the pH value of the bacterial suspension with a nitric acid solution; (5) uniformly mixing the bacterial suspension of step (4) and the lithium magnesium silicate inorganic gel of step (3), and allowing them to stand for rehydration to obtain a gel suspension; uniformly mixing the gel suspension with the sodium alginate hydrogel of step (3) to obtain a composite gel suspension; (6) Using a micro-syringe pump or a peristaltic pump, dropwise add the composite gel suspension of step (5) into the calcium salt solution, filter out the repair agent particles after sufficient cross-linking, place the repair agent particles in an ultra-clean workbench to air dry, and then place them in an oven to dry.

5. The preparation method according to claim 3, characterized in that In step (1): the drying temperature is 100°C to 110°C, The carbonization temperature is 400℃~700℃, the carbonization time is 0.5h~2h, and the heating rate is 2℃ / min~10℃ / min; The particle size of the biochar powder ranges from 0.5 μm to 300 μm.

6. The preparation method according to claim 3, characterized in that In step (2), the inoculation amount of the alkaliphilic microbial strain is 1% of the volume of the alkaline culture medium, the pH value of the alkaline culture medium is 9-10, the spore conversion promoting agent is mainly composed of anhydrous manganese sulfate, the addition amount of which is 0.16 g / L-0.2 g / L, the constant temperature shaking culture is carried out for 48 h to 96 h, the temperature is 25 ° C to 37 ° C, and the shaking rate is 160 r / min to 180 r / min.

7. The preparation method according to claim 3, characterized in that In step (3), the water bath temperature is 32° C. to 42° C., the mass volume concentration of the sodium alginate hydrogel is 1% to 2%, the mass volume concentration of the lithium magnesium silicate inorganic gel is 2% to 2.5%, the nutrient is one of casein peptone, soybean meal peptone, yeast extract powder, beef extract powder, peptone, urea, sucrose, and inosine, or a combination thereof, and the mass volume ratio of the nutrient to the sodium alginate hydrogel is 1 g:20 mL to 30 mL.

8. The preparation method according to claim 3, characterized in that: In step (4), the mass volume ratio of the biochar powder to the microbial spore culture solution is 1g:2mL~3mL, the concentration of the nitric acid solution is 0.8mol / L~1mol / L, and the pH value of the bacterial suspension is adjusted to 7~8; in step (5), the volume ratio of the bacterial suspension to the lithium magnesium silicate inorganic gel is 1:0.5~2, and the volume ratio of the gel suspension to the sodium alginate hydrogel is 1:0.5~2.

9. The preparation method according to claim 3, characterized in that In step (6): the mass concentration of the calcium salt solution is 1.8-2.5%.

10. Use of the microbial remediation agent particles according to claim 1 or the microbial remediation agent particles obtained by any preparation method of claims 2 to 9 in concrete repair.

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