A microbial material for seabed sediment mineralization and sand fixation and its application method

Abstract

The present invention provides a microbial material for mineralizing and fixing seabed sediments and its application method, specifically relating to the technical field of seabed sediment solidification. The application method uses a microbial material, which includes a hollow microbial solidification and sealing body, a calcium source urea capsule, spherical water grass mud particles, and sea sand; the calcium source urea capsule is placed in the inner cavity of the microbial solidification and sealing body; the spherical water grass mud particles include water grass mud containing nutrients and water grass seeds wrapped therein. The present invention induces the production of calcium carbonate minerals under the action of seawater, thereby forming a mineralized film on the seabed surface, so that the spherical water grass mud particles containing water grass seeds are stabilized in the microbial solidification and sealing body and sea sand, creating conditions for the reproduction of water grass seeds while effectively resisting the erosion of seabed bottom currents, solidifying the seabed surface, and further achieving the improvement of the seabed sediment.

Description

Technical Field

[0001] The patent of this invention relates to the field of seabed substrate solidification technology, specifically to a microbial material for seabed substrate mineralization and sand fixation and its application method. Background Art

[0002] In the field of marine engineering, the stability of offshore wind turbine and photovoltaic pile foundations is seriously threatened by seabed scour. Localized scour is particularly prominent in the complex marine environment characterized by wind, waves, and currents. Scour not only reduces pile foundation stability but can also cause resonance in the turbine structure, increasing fatigue stress and shortening the lifespan of the wind turbine. Therefore, scour protection for offshore wind and photovoltaic pile foundations is a key technology for ensuring their safe operation.

[0003] Traditional scour prevention methods include landfill (such as sand belts and rocks), soil consolidation, and geotextile coverings. However, these methods are prone to erosion in areas with high current velocities, leading to secondary scour. Furthermore, their effectiveness is limited in areas with high sediment loads and turbid waters. Therefore, developing new seabed improvement technologies is crucial for improving the stability and safety of offshore wind farms. Summary of the Invention

[0004] To overcome the above-mentioned deficiencies of the prior art, the present invention provides a microbial material for seabed sediment mineralization and sand fixation and its application method. The specific technical solution is as follows:

[0005] A microbial material for seabed substrate mineralization and sand fixation, comprising a hollow microbial solid carrier and sealing body, a calcium source urea capsule, spherical water grass mud particles and sea sand; the inner cavity of the calcium source urea capsule encapsulates a mixture of urea solution and calcium chloride solution; the calcium source urea capsule is placed in the inner cavity of the microbial solid carrier and sealing body; the spherical water grass mud particles include water grass mud containing nutrients and water grass seeds encapsulated therein; wherein the microbial solid carrier and sealing body, the spherical water grass mud particles and sea sand are mixed in a volume ratio of 1:1:2.

[0006] Preferably, the microorganism-immobilized and sealed body is prepared by immersing porous nano-culture balls in a suspension of active urease-producing bacteria extracted from marine sediments for 6 hours, and then placing the balls in a vacuum desiccator and evacuating the mixture using a vacuum pump for 8 to 10 hours.

[0007] Preferably, the active urease-producing bacterial suspension comprises a nutrient solution and bacteria cultured in the nutrient solution; the bacteria are selected from the group consisting of Bacillus lysinicus, Bacillus pasteurianus, and Ochrobacterium; the number of colonies in the active urease-producing bacterial suspension is 3.0×10 7 CFU / mL~5.0×10 7 CFU / mL.

[0008] Preferably, the ingredients of the nutrient solution include fish peptone, yeast extract powder and sodium chloride; wherein the concentration of fish peptone is 5-10 g / L, the concentration of yeast extract powder is 3-7 g / L, the concentration of sodium chloride is 5-10 g / L, and the pH value of the nutrient solution is equal to 7.

[0009] Preferably, the particle size of the porous nano-culture balls is 20 mm.

[0010] Also preferably, the capsule coating of the calcium source urea capsule comprises a capsule shell body, and both the inner and outer surfaces of the capsule shell body are sprayed with a cellulose triacetate coating.

[0011] Also preferably, the capsule shell body is made of a mixture of cold-soluble gelatin, glycerin and water; wherein the cold-soluble gelatin: glycerin: water are mixed in a volume ratio of 1:0.4-0.6:0.8-1.2.

[0012] Further preferably, the pH value of the mixed solution in the calcium source urea capsule is neutral; wherein the concentration of the urea solution is 1.0-1.5 mol / L; and the concentration of the calcium chloride solution is 0.8-1.2 mol / L.

[0013] Still further preferably, the clay, activated carbon, mineral powder, calcium oxalate, calcium silicate and silica sol in the water grass mud are mixed in a volume ratio of 12:4:2:2:1:1.

[0014] More preferably, a method for mineralizing and fixing seabed sediments using the above-mentioned microbial material specifically comprises the following steps:

[0015] S1. Prepare microbial immobilization and sealing bodies, calcium source urea capsules and spherical water grass mud particles, and screen sea sand with uniform particle size for standby;

[0016] S2. Mix the microbial solidified body, spherical waterweed mud particles, and sea sand in a volume ratio of 1:1:2, transport the mixture by ship to the seabed area to be solidified and improved, and evenly spray the mixture onto the seabed surface using a pump pipeline to form a covering layer;

[0017] S3. The cellulose triacetate coating on the outer surface of the calcium-source urea capsule within the microbial-immobilized container undergoes deacetylation under weakly alkaline seawater conditions, exposing the capsule shell. The cold-soluble gelatin within the capsule shell gradually dissolves in water until the inner cellulose triacetate coating is exposed. Further deacetylation occurs, disintegrating the capsule coating and releasing the mixed liquid within the capsule shell.

[0018] S4. The mixed solution decomposes into ammonia and carbon dioxide under the catalytic action of bacteria in the active urease-producing bacterial suspension. Then, in the alkaline environment of seawater, the ammonia is converted into ammonium ions and hydroxide ions, while the carbon dioxide is converted into carbonate ions and bicarbonate ions. These react with calcium ions in the seawater to form calcium carbonate, which then encapsulates the microbial immobilization body, the spherical waterweed mud particles, and the sea sand.

[0019] S5. After 14 to 28 days, calcium carbonate will fill the gaps between the microbial solid sealing body, spherical water grass mud particles and sea sand and connect them to form a mineralized film. The spherical water grass mud particles will be stabilized in the microbial solid sealing body and sea sand. The water grass seeds will begin to grow based on the nutrients in the water grass mud, and their roots will penetrate into the lower mud and sand, and together with the mineralized layer, they will complete the solidification and improvement of the seabed bottom.

[0020] The beneficial effects of the present invention are:

[0021] 1. This invention induces the production of calcium carbonate minerals under the action of seawater, thereby forming a mineralized film on the seabed surface. This stabilizes the spherical waterweed mud particles containing waterweed seeds in the microbial immobilization and sealing body and sea sand. This creates conditions for the reproduction of waterweed seeds while effectively resisting erosion by low-lying seabed currents, solidifying the seabed surface and achieving improvement in the seabed substrate.

[0022] 2. The preparation method of the present invention is simple and easy to implement. Mixing the microbial material with sea sand can also effectively reduce the cost of improving the seabed substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings that constitute the specification of this application are used to provide further understanding of this application and do not constitute improper limitations on this application.

[0024] Figure 1 A diagram showing the process of forming a mineralized film using the microbial material of the present invention;

[0025] Figure 2 To finally form a mineralized film. DETAILED DESCRIPTION

[0026] The specific implementation methods of a microbial material for seabed sediment mineralization and sand fixation and its application method provided by the present invention are further described in conjunction with the accompanying drawings and examples.

[0027] A microbial material for seabed bottom mineralization and sand fixation, comprising a hollow microbial solidification and sealing body, calcium source urea capsules, spherical water grass mud particles and sea sand;

[0028] The microorganism-immobilized and sealed body is prepared by soaking the porous nano-culture balls in a suspension of active urease-producing bacteria extracted from marine sediments for 6 hours, and then placing the balls in a vacuum dryer and using a vacuum pump to evacuate the air for 8 to 10 hours to dry and remove foreign bacteria. Preferably, the porous nano-culture balls have a particle size of 20 mm.

[0029] Preferably, the active urease-producing bacterial suspension comprises a nutrient solution and bacteria cultured in the nutrient solution; the bacteria are selected from the group consisting of Bacillus lysinicus, Bacillus pasteurianus, and Ochrobacterium. The number of colonies in the active urease-producing bacterial suspension is 3.0×10 7 CFU / mL~5.0×10 7 CFU / mL; the ingredients of the nutrient solution include fish peptone, yeast extract powder and sodium chloride; wherein the concentration of fish peptone is 5-10g / L, the concentration of yeast extract powder is 3-7g / L, the concentration of sodium chloride is 5-10g / L, and the pH value of the nutrient solution is equal to 7.

[0030] Preferably, the calcium source urea capsule is placed in the inner cavity of the microorganism immobilization and sealing body, and the inner cavity of the calcium source urea capsule encapsulates the mixture of urea solution and calcium chloride solution and keeps the pH value of the mixture neutral; wherein, the concentration of the urea solution is 1.0-1.5 mol / L; the concentration of the calcium chloride solution is 0.8-1.2 mol / L.

[0031] It's worth noting that to ensure the calcium-source urea capsule's internal solution doesn't dissolve the capsule coating before re-entering seawater, the capsule's coating is prepared using the following method: It includes a capsule shell, the inner and outer surfaces of which are spray-coated with a cellulose triacetate (CTA) coating. The shell is made from a mixture of cold-melting gelatin, glycerin, and water, with the cold-melting gelatin: glycerin: water being mixed in a volume ratio of 1:0.4-0.6:0.8-1.2. The basic principle is that the calcium-source urea mixed solution inside the capsule coating is neutral and does not chemically react with the cellulose triacetate (CTA) coating on the inner surface, thus having good anti-melting properties. During capsule preparation, storage, transportation, and other dry environments, the inside and outside of the capsule are in a stable state and will not melt on their own. However, when exposed to seawater, the cellulose triacetate (CTA) coating on the outer surface of the capsule coating will undergo a deacetylation reaction under weakly alkaline seawater conditions, exposing the capsule shell body. The cold-soluble gelatin contained therein will gradually melt in water, exposing the cellulose triacetate (CTA) coating on the inner surface and continuing to undergo deacetylation, eventually causing the capsule coating to disintegrate and release the calcium-source urea mixed solution in the capsule cavity.

[0032] It is also preferred that the spherical water grass mud particles include water grass mud containing nutrients and water grass seeds wrapped inside thereof; wherein the clay, activated carbon, mineral powder, calcium oxalate, calcium silicate and silica sol in the water grass mud are mixed in a volume ratio of 12:4:2:2:1:1.

[0033] Further preferably, the microorganism solid sealing body, spherical water grass mud particles and sea sand are mixed in a volume ratio of 1:1:2.

[0034] During the application, first, prepare the microbial solid-carrying sealing body, calcium source urea capsule and spherical aquatic plant mud particles, and screen the sea sand with uniform particle size for use; then, mix the microbial solid-carrying sealing body, spherical aquatic plant mud particles and sea sand in a volume ratio of 1:1:2, transport them by ship to the seabed area to be solidified and improved, and use a pumping pipeline to evenly spray them on the seabed surface to form a covering layer; then, the triacetate cellulose coating on the outer surface of the calcium source urea capsule in the cavity of the microbial solid-carrying sealing body undergoes a deacetylation reaction under weakly alkaline seawater conditions and exposes the capsule body, and the cold-soluble gelatin in the capsule body gradually melts in water until the triacetate cellulose coating on the inner surface is exposed, and then the deacetylation reaction continues to occur, causing the capsule coat to disintegrate and release the mixed liquid in the capsule coat cavity; then Afterwards, the mixed liquid decomposes into ammonia and carbon dioxide under the catalytic action of bacteria in the active urease-producing bacteria suspension, and then in the alkaline environment of seawater, ammonia is converted into ammonia ions and hydroxide ions, and carbon dioxide is converted into carbonate ions and bicarbonate ions, and reacts with calcium ions in seawater to form calcium carbonate. Calcium carbonate wraps the microbial solid sealing body, spherical water grass mud particles and sea sand; finally, after 14 to 28 days, calcium carbonate fills the gaps between the microbial solid sealing body, spherical water grass mud particles and sea sand and connects them to form a mineralized film. The spherical water grass mud particles are stabilized in the microbial solid sealing body and sea sand. The water grass seeds begin to grow relying on the nutrients in the water grass mud, and the roots penetrate into the lower mud and sand, and together with the mineralized layer, complete the solidification and improvement of the seabed bottom.

[0035] Example:

[0036] S1. Preparation of microbial immobilized and sealed bodies and calcium source urea capsules:

[0037] The nutrient solution with the concentration of fish peptone 10 g / L, yeast extract powder 5 g / L, and sodium chloride 10 g / L was used to prepare a bacterial concentration of 5.0 × 10 7 CFU / mL of Bacillus lysininus suspension was prepared, and a 20 mm diameter porous nanoparticle culture ball (hollow interior) was immersed in the suspension for 6 hours before being removed. The soaked porous nanoparticle culture ball was then placed in a vacuum desiccator and evacuated with a vacuum pump for 8 hours to obtain a microorganism-immobilized and sealed body, which was then stored in a dry environment at room temperature.

[0038] A calcium source urea mixture was prepared using a 1.0 mol / L urea solution and a 0.8 mol / L calcium chloride solution (the pH value of the mixture was adjusted to 7 by hydrochloric acid); a capsule shell body was prepared using cold-soluble gelatin: glycerol: water in a volume ratio of 1:0.4:0.8, and a cellulose triacetate coating was sprayed on the inner and outer surfaces of the capsule shell body to prepare a capsule coating; the mixture and the capsule coating were encapsulated, and the prepared calcium source urea capsule was placed in the inner cavity of a microbial solid sealing body and stored in a dry environment at room temperature.

[0039] S2. Preparation of spherical water grass mud particles:

[0040] The cement grass and water grass seeds containing nutrients are rolled into small particles in a material making machine. Water is sprayed during the forming process to ensure the formation of particles. The spherical water grass mud particles obtained must be used within 24 hours after preparation.

[0041] The ingredients of cement grass include the following components as shown in Table 1 below:

[0042] Table 1: Cement grass ingredients

[0043] clay activated carbon Ore powder calcium oxalate calcium silicate Silica Sol 70 20 10 10 5 5

[0044] S3. Preparation of microbial materials:

[0045] The microbial solid sealing body obtained above, the spherical water grass mud particles and the sea sand are mixed in a volume ratio of 1:1:2 to obtain the microbial material for use.

[0046] S4. Seabed solidification and improvement method:

[0047] S4.1 Prepare microbial immobilization and sealing bodies, calcium source urea capsules, and spherical water grass mud particles, and select sea sand with uniform particle size for later use;

[0048] S4.2 The microbial material obtained in S3 is transported by ship to the seabed area to be solidified and improved, and is evenly sprayed on the seabed surface through a pumping pipeline to form a covering layer;

[0049] S4.3 The cellulose triacetate (CTA) coating on the outer surface of the calcium source urea capsule in the cavity of the microbial immobilization and sealing body undergoes a deacetylation reaction under weakly alkaline seawater conditions (see Reaction Formula 1), exposing the capsule shell. The cold-soluble gelatin contained therein gradually dissolves in water, exposing the cellulose triacetate (CTA) coating on the inner surface and continuing to undergo deacetylation, eventually causing the capsule shell to disintegrate and release the calcium source urea mixture in the capsule cavity;

[0050] S4.4 High concentration of calcium source urea is decomposed into ammonia (NH3) and carbon dioxide (CO2) under the catalysis of Bacillus lysinicus (see reaction formula 2). Then, in the alkaline environment of seawater, ammonia (NH3) is hydrated to form ammonium ions (NH4 - ) and hydroxide ions (OH - ), CO2 is converted into carbonate ions (CO3 2- ) and bicarbonate ions (HCO3 - ), (see reaction formula 3-5), and with calcium ions (Ca 2+ ) reacts to form calcium carbonate (CaCO3) (see reaction formula 6), which gradually wraps the microbial solidification and sealing body, spherical water grass mud particles and sea sand. Figure 1 As shown;

[0051] S4.5 After 14 to 28 days, calcium carbonate will fill the gaps between the microbial solidification and sealing body, the spherical water grass mud particles and the sea sand and connect them to form a mineralized film. The spherical water grass mud particles will be stabilized in the microbial solidification and sealing body and the sea sand. The water grass seeds will begin to grow based on the nutrients in the water grass mud and their roots will penetrate into the lower mud and sand, and together with the mineralized layer, they will complete the solidification and improvement of the seabed bottom. Figure 2 shown.

[0052] Among them, under weakly alkaline seawater conditions, the main chemical reaction of the deacetylation reaction of cellulose triacetate (CTA) coating can be expressed as:

[0053] CTA+OH - →CA+AcO-CTA+OH - →CA+AcO - (1);

[0054] Wherein, CTA is cellulose triacetate, OH - is hydroxide ion, CA is cellulose, AcO - Acetate ions; the acetyl group in CTA is hydrolyzed under alkaline conditions to produce cellulose and acetate ions.

[0055]

[0056] The present invention provides an efficient and environmentally friendly method for improving seabed substrate, which solidifies the seabed surface through microbial mineralization, creating conditions for the reproduction of aquatic grass seeds while effectively enhancing the seabed's ability to resist scouring and promoting the recovery of marine habitats.

[0057] In the present invention, the orientation or positional relationship indicated by terms such as "upper", "lower", "bottom", "top", etc. is based on the orientation or positional relationship shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationship of the various parts or elements of the present invention. They do not specifically refer to any part or element in the present invention and cannot be understood as limiting the present invention. Terms such as "connected" and "connect" should be understood in a broad sense, indicating that they can be fixedly connected, integrally connected, or detachably connected; they can be directly connected or indirectly connected through an intermediate medium. For relevant scientific research or technical personnel in this field, the specific meaning of the above terms in the present invention can be determined according to the specific circumstances, and they cannot be understood as limiting the present invention.

[0058] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A microbial material for seabed mineralization and sand fixation, characterized in that: It includes a hollow microorganism solid-carrying and sealing body, calcium source urea capsules, spherical water grass mud particles and sea sand; The inner cavity of the calcium source urea capsule contains a mixture of urea solution and calcium chloride solution; The calcium source urea capsule is placed in the inner cavity of the microorganism immobilization and sealing body; The spherical water grass mud particles include water grass mud containing nutrients and water grass seeds wrapped therein; Among them, the microbial solidification and sealing body, spherical water grass mud particles and sea sand are mixed in a volume ratio of 1:1:2; The microorganism immobilization and sealing body is prepared by soaking porous nano-culture balls in a suspension of active urease-producing bacteria extracted from marine sediments for 6 hours, and then placing them in a vacuum desiccator and using a vacuum pump to evacuate for 8 to 10 hours. The active urease-producing bacterial suspension comprises a nutrient solution and bacteria cultured in the nutrient solution; The bacteria is one of lysinic Bacillus, pasteurian Bacillus or Ochrobacterium; The colony count of the active urease-producing bacteria suspension was 3.0×10 7 CFU / mL~5.0×10 7 CFU / mL; The capsule coating of the calcium source urea capsule comprises a capsule shell body, and the inner and outer surfaces of the capsule shell body are sprayed with a cellulose triacetate coating.

2. The microbial material for seabed mineralization and sand fixation according to claim 1, characterized in that: The ingredients of the nutrient solution include fish peptone, yeast extract powder and sodium chloride; Among them, the concentration of fish peptone is 5-10 g / L, the concentration of yeast extract powder is 3-7 g / L, the concentration of sodium chloride is 5-10 g / L, and the pH value of the nutrient solution is equal to 7.

3. The microbial material for seabed mineralization and sand fixation according to claim 1, characterized in that: The particle size of the porous nano-bacteria culture ball is 20 mm.

4. The microbial material for seabed mineralization and sand fixation according to claim 1, characterized in that: The capsule shell body is made of a mixture of cold-soluble gelatin, glycerin and water; Among them, cold-soluble gelatin: glycerol: water are mixed in a volume ratio of 1:0.4~0.6:0.8~1.

2.

5. The microbial material for seabed mineralization and sand fixation according to claim 4, characterized in that: The pH value of the mixed solution in the calcium source urea capsule is neutral; The concentration of the urea solution is 1.0-1.5 mol / L; the concentration of the calcium chloride solution is 0.8-1.2 mol / L.

6. The microbial material for seabed mineralization and sand fixation according to claim 1, characterized in that: The clay, activated carbon, mineral powder, calcium oxalate, calcium silicate and silica sol in the water grass mud are mixed in a volume ratio of 12:4:2:2:1:

1.

7. A method for mineralizing and fixing seabed sediments, using the microbial material according to any one of claims 1 to 6, characterized in that: The specific steps include: S1. Prepare microbial immobilization and sealing bodies, calcium source urea capsules and spherical water grass mud particles, and screen sea sand with uniform particle size for standby; S2. Mix the microbial solidified body, spherical waterweed mud particles, and sea sand in a volume ratio of 1:1:2, transport the mixture by ship to the seabed area to be solidified and improved, and evenly spray the mixture onto the seabed surface using a pump pipeline to form a covering layer; S3. The cellulose triacetate coating on the outer surface of the calcium-source urea capsule within the microbial-immobilized container undergoes deacetylation under weakly alkaline seawater conditions, exposing the capsule shell. The cold-soluble gelatin within the capsule shell gradually dissolves in water until the inner cellulose triacetate coating is exposed. Further deacetylation occurs, disintegrating the capsule coating and releasing the mixed liquid within the capsule shell. S4. The mixed solution decomposes into ammonia and carbon dioxide under the catalytic action of bacteria in the active urease-producing bacterial suspension. Then, in the alkaline environment of seawater, the ammonia is converted into ammonium ions and hydroxide ions, while the carbon dioxide is converted into carbonate ions and bicarbonate ions. These react with calcium ions in the seawater to form calcium carbonate, which then encapsulates the microbial immobilization body, the spherical waterweed mud particles, and the sea sand. S5. After 14 to 28 days, calcium carbonate will fill the gaps between the microbial solid sealing body, spherical water grass mud particles and sea sand and connect them to form a mineralized film. The spherical water grass mud particles will be stabilized in the microbial solid sealing body and sea sand. The water grass seeds will begin to grow based on the nutrients in the water grass mud, and their roots will penetrate into the lower mud and sand, and together with the mineralized layer, they will complete the solidification and improvement of the seabed bottom.

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