Method for improving water erosion resistance of soil based on MICP

Abstract

The invention provides a method for improving water erosion resistance of soil based on MICP, and belongs to the technical field of environmental protection. A soil erosion resisting agent is added into the soil, the soil erosion resisting agent is coal ash loaded with urea, calcium chloride, bacillus pasteurii and bacillus subtilis, and the adding amount of the soil erosion resisting agent is 100-200 g sprayed on the surface of the soil per 1 m < 2 >. Calcium carbonate in the soil is deposited through the activity of bacteria, original inter-particle pores are filled along with continuous deposition of the calcium carbonate, soil particles are changed into a whole from loose particles, and the mechanical property of the soil is enhanced. According to the method, the water erosion resistance of the soil can be greatly improved, and the environmental protection capability is improved.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection, and in particular to a method for improving soil resistance to water erosion based on MICP. Background Art

[0002] In the construction of construction land, roads, dams, etc., earth is filled and cut. If the slope formed by this is left directly, it will be eroded by rainfall, weathering, etc., resulting in landslides, stone rolling and other accidents. Therefore, the patent document Japanese Patent No. 4048800 prevents soil erosion by spraying a spray material mixed with an anti-soil desiccant at a ratio of 0.5-1.5 kg relative to 1 m3 of the spray material to the slope. The anti-soil desiccant contains a water-swellable water-absorbing resin, a surfactant and a synthetic resin emulsion. However, this method is relatively costly.

[0003] MICP technology, namely microbial induced calcium carbonate deposition technology, is a common biological induced mineralization reaction process. In essence, it uses a certain type of bacteria in nature, whose metabolism can produce urease that decomposes urea. The carbonate ions produced after the decomposition of urea combine with free metal cations in nature to form gelled crystals. The application of MICP technology has low requirements for production energy consumption and production costs, and can also reduce greenhouse gas emissions. MICP technology can improve the geological properties of soil, so it can be used as an alternative geological reinforcement technology. Summary of the invention

[0004] The purpose of the present invention is to propose a method for improving soil water erosion resistance based on MICP. Through the activity of bacteria, calcium carbonate is deposited in the soil. As calcium carbonate is continuously deposited, the original pores between particles are filled, and the soil particles are transformed from loose particles into a whole, and their mechanical properties are enhanced. The method of the present invention can greatly improve the soil's water erosion resistance and improve the ability of environmental protection.

[0005] The technical solution of the present invention is achieved in this way:

[0006] The invention provides a method for improving soil water erosion resistance based on MICP. A soil erosion resistance agent is added into the soil. The soil erosion resistance agent is fly ash loaded with urea, calcium chloride, Bacillus pasteurianus and Bacillus subtilis.

[0007] As a further improvement of the present invention, the preparation method of the soil erosion inhibitor is as follows:

[0008] S1. Inoculating Bacillus pasteurianus and Bacillus subtilis into a slant culture medium, activating the culture, and obtaining a composite bacterial activation solution;

[0009] S2. Add fly ash to ethanol, add a silane coupling agent, heat and stir to react, filter, wash, and dry to obtain modified fly ash;

[0010] S3. Add the modified fly ash into the composite bacteria activation liquid, add urea and calcium chloride, stir and mix evenly, freeze-dry, and prepare the anti-soil erosion agent.

[0011] As a further improvement of the present invention, the mass ratio of Bacillus pasteurianus to Bacillus subtilis is 10:3-5.

[0012] As a further improvement of the present invention, the activation culture condition is 35-40° C., and the activation culture is 18-24 hours.

[0013] As a further improvement of the present invention, the bacterial content in the composite bacteria activation solution is 10 10 -10 11 cfu / mL.

[0014] As a further improvement of the present invention, the mass ratio of the silane coupling agent to the fly ash is 1-2:10.

[0015] As a further improvement of the present invention, the silane coupling agent is at least one of KH550, KH602, and KH792.

[0016] As a further improvement of the present invention, the temperature of the heating and stirring reaction is 45-55° C. and the time is 1-3 h.

[0017] As a further improvement of the present invention, the mass ratio of the modified fly ash, urea, calcium chloride and composite bacteria activation liquid is 10:0.5-1:0.1-0.2:2-4.

[0018] As a further improvement of the present invention, the amount of the anti-soil erosion agent added is per 1m 2 Spray 100-200g on the soil surface.

[0019] The present invention has the following beneficial effects:

[0020] The method of the present invention can greatly improve the soil's ability to resist water erosion. Bacteria are adsorbed on the surface of soil particles. Due to the difference in nutrient solution concentration gradient inside and outside the cells, nutrients such as urea outside the cells migrate from the cell membrane into the interior of the cells. Through the metabolic process of bacteria under alkaline conditions, urease in Bacillus pasteurianus converts the carbon source in the nutrients into carbon dioxide and the nitrogen source into ammonia. Ammonia and carbon dioxide are hydrolyzed in the extracellular liquid environment. Since the hydrolysis of ammonia increases the pH value of the environment, OH in the extracellular solution is - The increase in ion concentration neutralizes the H+ ions produced by the hydrolysis of carbon dioxide and makes HCO3 - The hydrolysis balance is constantly moving towards the production of CO3 2- In the direction of2- At the same time, because the extracellular space often carries negatively charged ionic groups such as hydroxyl, amino, amide, and carboxylic acid, it will adsorb Ca in the solution environment. 2+ Mg 2+ ions, and Ca 2+ Mg 2+ With CO3 2- The ions combine and mineralize on the surface of soil particles to form calcium carbonate. As calcium carbonate continues to deposit, the original pores between particles are filled, and the soil particles change from loose particles to a whole, and their mechanical properties are enhanced. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1

[0023] This embodiment provides a method for improving soil water erosion resistance based on MICP, adding soil erosion resistance agent to the soil, the addition amount is 2 Spray 100g on the soil surface and continue treating for 7 days.

[0024] The preparation method of the soil erosion inhibitor is as follows:

[0025] S1. Inoculate 1g of Bacillus pasteurianus and 0.3g of Bacillus subtilis into a slant culture medium and activate and culture at 35℃ for 18h to obtain a composite bacterial activation solution with a bacterial content of 10 10 -10 11 cfu / mL;

[0026] S2. Add 10 g of fly ash to 100 mL of ethanol, add 1 g of silane coupling agent KH602, heat to 45 ° C, stir and react for 1 h, filter, wash, and dry to obtain modified fly ash;

[0027] S3. Add 10 g of modified fly ash to 20 g of composite bacteria activation liquid, add 0.5 g of urea and 0.1 g of calcium chloride, stir and mix for 30 minutes, and freeze-dry to obtain an anti-soil erosion agent.

[0028] Example 2

[0029] This embodiment provides a method for improving soil water erosion resistance based on MICP, adding soil erosion resistance agent to the soil, the addition amount is 2 Spray 200g on the soil surface and continue treating for 7 days.

[0030] The preparation method of the soil erosion inhibitor is as follows:

[0031] S1. Inoculate 1g of Bacillus pasteurianus and 0.5g of Bacillus subtilis into a slant culture medium and activate and culture at 40℃ for 24h to obtain a composite bacterial activation solution with a bacterial content of 10 10 -10 11 cfu / mL;

[0032] S2. Add 10 g of fly ash to 100 mL of ethanol, add 2 g of silane coupling agent KH550, heat to 55 ° C, stir and react for 3 h, filter, wash, and dry to obtain modified fly ash;

[0033] S3. Add 10 g of modified fly ash to 40 g of composite bacteria activation liquid, add 0.5 g of urea and 0.1 g of calcium chloride, stir and mix for 30 minutes, and freeze-dry to obtain an anti-soil erosion agent.

[0034] Example 3

[0035] This embodiment provides a method for improving soil water erosion resistance based on MICP, adding soil erosion resistance agent to the soil, the addition amount is 2 Spray 150g on the soil surface and continue treating for 7 days.

[0036] The preparation method of the soil erosion inhibitor is as follows:

[0037] S1. Inoculate 1g of Bacillus pasteurianus and 0.4g of Bacillus subtilis into the slant culture medium and activate and culture at 37℃ for 21h to obtain a composite bacterial activation solution with a bacterial content of 10 10 -10 11 cfu / mL;

[0038] S2. Add 10 g of fly ash to 100 mL of ethanol, add 1.5 g of silane coupling agent KH792, heat to 50 ° C, stir and react for 2 h, filter, wash, and dry to obtain modified fly ash;

[0039] S3. Add 10 g of modified fly ash to 30 g of composite bacteria activation liquid, add 0.7 g of urea and 0.15 g of calcium chloride, stir and mix for 30 minutes, and freeze-dry to obtain an anti-soil erosion agent.

[0040] Test Example 1

[0041] The method in Examples 1-3 was used to improve the soil's ability to resist water erosion, and the soil outflow in each group was tested. The results are shown in Table 1, with no addition of soil erosion inhibitor as the control.

[0042] Table 1

[0043] Group Soil outflow (g) Control group 22.4 Example 1 23.9 Example 2 21.7 Example 3 182.8

[0044] It can be seen from the above table that the methods in Examples 1-3 of the present invention have a good ability to improve the soil's resistance to water erosion.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for improving soil resistance to water erosion based on MICP, characterized in that: An anti-soil erosion agent is added to the soil, wherein the anti-soil erosion agent is fly ash loaded with urea, calcium chloride, Bacillus pasteurianus and Bacillus subtilis.

2. The method for improving soil water erosion resistance based on MICP according to claim 1, characterized in that: The preparation method of the soil erosion inhibitor is as follows: S1. Inoculating Bacillus pasteurianus and Bacillus subtilis into a slant culture medium, activating the culture, and obtaining a composite bacterial activation solution; S2. Add fly ash to ethanol, add a silane coupling agent, heat and stir to react, filter, wash, and dry to obtain modified fly ash; S3. Add the modified fly ash into the composite bacteria activation liquid, add urea and calcium chloride, stir and mix evenly, freeze-dry, and prepare the anti-soil erosion agent.

3. The method for improving soil water erosion resistance based on MICP according to claim 2, characterized in that: The mass ratio of the Bacillus pasteurianus to the Bacillus subtilis is 10:3-5.

4. The method for improving soil water erosion resistance based on MICP according to claim 2, characterized in that: The activation culture is carried out at 35-40° C. for 18-24 hours.

5. The method for improving soil water erosion resistance based on MICP according to claim 2, characterized in that: The bacterial content of the composite bacteria activation solution is 10 10 -10 11 cfu / mL.

6. The method for improving soil water erosion resistance based on MICP according to claim 2, characterized in that: The mass ratio of the silane coupling agent to fly ash is 1-2:

10.

7. The method for improving soil water erosion resistance based on MICP according to claim 2, characterized in that: The silane coupling agent is at least one of KH550, KH602 and KH792.

8. The method for improving soil water erosion resistance based on MICP according to claim 2, characterized in that: The temperature of the heating and stirring reaction is 45-55° C. and the time is 1-3 hours.

9. The method for improving soil water erosion resistance based on MICP according to claim 2, characterized in that: The mass ratio of the modified fly ash, urea, calcium chloride and composite bacteria activation liquid is 10:0.5-1:0.1-0.2:2-4.

10. The method for improving soil water erosion resistance based on MICP according to claim 1, characterized in that: The amount of soil erosion inhibitor added is per 1m 2 Spray 100-200g on the soil surface.