A soil remediation system based on desulfurized gypsum and microorganisms

Abstract

The embodiment of the present application relates to the technical field of soil remediation, in particular to a soil remediation system based on desulfurization gypsum and microorganisms, comprising: a desulfurization gypsum treatment assembly, which is used for preparing desulfurization gypsum powder and desulfurization gypsum slurry by taking desulfurization gypsum generated by a coal-fired power plant as raw material; a mineralization bacteria preparation assembly, which is used for obtaining desulfurization gypsum source functional mineralization bacteria liquid by taking desulfurization gypsum powder as an initial bacteria source; a soil plowing assembly, which is used for plowing the soil to be remediated after a spraying assembly applies desulfurization gypsum slurry to the soil to be remediated, so that the soil to be remediated is uniformly mixed with the desulfurization gypsum slurry to obtain pre-improved soil; and the pre-improved soil to which a remediation reaction liquid is applied is plowed to precipitate target heavy metal ions in the pre-improved soil. The technical scheme of the present application can improve the remediation effect of saline-alkali and heavy metal contaminated soil, and avoid the environmental risk caused by the storage of desulfurization gypsum.

Description

Technical Field

[0001] This invention relates to the field of soil remediation technology, and in particular to a soil remediation system based on the synergistic effect of desulfurized gypsum and microorganisms. Background Technology

[0002] Coal-fired power plants generate large amounts of desulfurization gypsum during flue gas desulfurization (FGD) processes. The storage and disposal of this gypsum not only occupies land but also poses environmental risks. Current technologies allow for the use of desulfurization gypsum in saline-alkali land remediation; however, its effectiveness is highly dependent on abundant leaching water and requires specific drainage conditions, limiting its application in arid or poorly drained areas. Furthermore, the remediation effect is not sustainable. In addition, salinization pollution often coexists with heavy metal pollution in the soil to be remediated, and desulfurization gypsum is ineffective in remediating soils contaminated with heavy metals.

[0003] Therefore, there is an urgent need to develop a new technical solution to solve the above-mentioned technical problems. Summary of the Invention

[0004] This invention provides a soil remediation system based on the synergy of desulfurized gypsum and microorganisms, which can improve the remediation effect of salinized and heavy metal contaminated soils and avoid the environmental risks caused by the stockpiling of desulfurized gypsum.

[0005] In a first aspect, the present invention provides a soil remediation system based on the synergistic effect of desulfurized gypsum and microorganisms, comprising: A desulfurized gypsum treatment component includes a crushing device and a first mixing tank. The crushing device includes a first outlet and a second outlet for crushing desulfurized gypsum produced by a coal-fired power plant to obtain desulfurized gypsum powder. The first mixing tank is connected to the first outlet of the crushing device and is used to receive a first portion of the desulfurized gypsum powder and to mix the desulfurized gypsum powder with water to obtain a desulfurized gypsum slurry. The mineralizing bacteria preparation component is connected to the second outlet of the pulverizing device and is used to receive the second part of desulfurized gypsum powder. The desulfurized gypsum powder is used as the initial bacterial source and inoculated into a prepared enrichment culture medium for enrichment culture and subculture to obtain desulfurized gypsum source functional mineralizing bacteria solution. The nitrogen source in the enrichment culture medium is urea. The first spraying component is connected to the first mixing tank and is used to spray the desulfurized gypsum slurry onto the soil to be remediated. The second mixing tank is connected to the mineralization bacteria preparation component and is used to mix the desulfurized gypsum source functional mineralization bacteria liquid with urea solution to obtain a repair reaction solution. The soil tillage assembly is used to tillage the soil to be repaired after the spraying assembly applies desulfurized gypsum slurry to the soil to be repaired, so as to mix the soil to be repaired with the desulfurized gypsum slurry evenly to obtain pre-improved soil; and to tillage the pre-improved soil to which the remediation reaction solution has been applied, so as to precipitate the target heavy metal ions in the pre-improved soil and realize the remediation of the pre-improved soil.

[0006] This invention provides a soil remediation system based on the synergistic effect of desulfurized gypsum and microorganisms. It can prepare desulfurized gypsum slurry and powder for soil remediation using desulfurized gypsum produced from coal-fired power plants as raw material. This not only avoids the environmental risks associated with desulfurized gypsum stockpiling but also reduces the cost of remediation materials. The introduction of a microbial-induced mineralization process reduces the dependence of desulfurized gypsum remediation on abundant leaching water and a complete drainage system, broadening its applicability in arid, semi-arid, or poorly drained areas. Combining the chemical remediation effect of desulfurized gypsum with the biomineralization effect of desulfurized gypsum-derived functional mineralizing bacterial solution simultaneously addresses the problems of salinization and heavy metal pollution. Furthermore, the desulfurized gypsum-derived functional mineralizing bacterial solution is directly screened and acclimatized from desulfurized gypsum, resulting in bacterial agents with natural tolerance to high-calcium, high-salt, and heavy metal environments. This high compatibility with desulfurized gypsum raw materials improves the remediation effect and the durability of the remediation effect. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the structure of a soil remediation system based on the synergistic effect of desulfurized gypsum and microorganisms according to an embodiment of the present invention; Figure 2 This is a schematic diagram of another soil remediation system based on the synergy of desulfurized gypsum and microorganisms provided in an embodiment of the present invention.

[0009] Figure label: 10-Desulfurization gypsum treatment component; 11- Crushing device; 12 - First mixing tank; 20-Mineralizing bacteria preparation components; 21-Enrichment culture unit; 22-Accustomed Cultivation Unit; 221 - Acclimatization and cultivation tank; 222 - First Dosing Inoculation Tube; 223 - Extraction solution addition device; 224 - Second Shaking Incubator; 23-Extraction preparation unit; 231 - Extract mixing tank; 232 - First Shaking Incubator; 233 - Solid-liquid separation device; 30 - First spraying component; 40 - Second mixing tank; 50 - Soil Tillage Components. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0011] Please refer to Figures 1-2 This invention provides a soil remediation system based on the synergistic effect of desulfurized gypsum and microorganisms, comprising: The desulfurized gypsum treatment component 10 includes a crushing device 11 and a first mixing tank 12. The crushing device 11 includes a first outlet and a second outlet, which are used to crush the desulfurized gypsum produced by the coal-fired power plant to obtain desulfurized gypsum powder. The first mixing tank 12 is connected to the first outlet of the crushing device 11 and is used to receive a first portion of the desulfurized gypsum powder and to mix the desulfurized gypsum powder with water to obtain desulfurized gypsum slurry. The mineralization bacteria preparation component 20 is connected to the second outlet of the pulverizing device 11 and is used to receive the second part of desulfurized gypsum powder. The desulfurized gypsum powder is used as the initial bacterial source and is introduced into the prepared enrichment culture medium for enrichment culture and subculture to obtain desulfurized gypsum source functional mineralization bacteria solution. The nitrogen source in the enrichment culture medium is urea. The first spraying component 30 is connected to the first mixing tank 12 and is used to spray desulfurized gypsum slurry onto the soil to be remediated. The second mixing tank 40 is connected to the mineralization bacteria preparation component 20 and is used to mix the desulfurized gypsum source functional mineralization bacteria liquid with urea solution to obtain the repair reaction liquid. The soil tillage component 50 is used to tillage the soil to be repaired after the spraying component applies desulfurized gypsum slurry to the soil to be repaired, so as to mix the soil to be repaired with the desulfurized gypsum slurry evenly to obtain pre-improved soil; and to tillage the pre-improved soil to which the repair reaction solution has been applied, so as to precipitate the target heavy metal ions in the pre-improved soil and realize the repair of the pre-improved soil.

[0012] In this embodiment of the invention, desulfurized gypsum produced by a coal-fired power plant is recycled using a desulfurized gypsum treatment component 10. Using desulfurized gypsum as raw material, desulfurized gypsum powder is prepared by a pulverizing device 11. The powder is then stirred with water in a first mixing tank 12 to obtain a desulfurized gypsum slurry. This slurry is generated by mixing a portion of the desulfurized gypsum powder with water. A second portion of the desulfurized gypsum powder from the second outlet of the pulverizing device 11 is selected. The mineralization bacteria preparation component 20 uses Bacillus subtilis present in the desulfurized gypsum as the initial bacterial source, inoculated into an enrichment culture medium for enrichment and subculturing to obtain a desulfurized gypsum-derived functional mineralization bacteria solution. During the acclimation process, the high salt and high calcium environment of the desulfurized gypsum itself, along with urea (nitrogen source) in the culture medium, serves as selection pressure to screen for indigenous dominant bacterial groups (desulfurized gypsum-derived functional mineralization bacteria) that can tolerate the gypsum environment and possess high urease production activity. Desulfurized gypsum slurry and desulfurized gypsum-derived functional mineralizing bacteria solution are synergistically applied to the soil to be remediated. The desulfurized gypsum slurry is applied to the soil through the first spraying component 30, followed by tilling the soil using the soil tilling component 50 to ensure uniform mixing of the desulfurized gypsum slurry and the soil. The mixture is then left to stand for 3-5 days to obtain pre-treated improved soil. Next, the desulfurized gypsum-derived functional mineralizing bacteria solution is mixed with urea solution in the second mixing tank 40 to obtain a remediation reaction solution, which is then uniformly applied to the contaminated soil. The soil tilling component 50 is then used again to till the soil, ensuring even distribution of the remediation reaction solution.

[0013] Specifically, after applying desulfurized gypsum slurry to the soil to be remediated, part of the desulfurized gypsum slurry... In the replacement While promoting elution, it also acts as a cationic bridge between clay particles and organic matter, promoting the cementation of single particles into micro-aggregates. Applying desulfurized gypsum slurry enhances the aggregation of mineral soil particles, increases soil mechanical stability and the number of water-stable aggregates, and the effect increases with the application rate. Furthermore, applying desulfurized gypsum slurry promotes the formation of new pores in the topsoil, increases soil permeability, and rapidly captures pollutants from the soil solution. This process generates tiny calcium carbonate crystal nuclei, rapidly lowering the soil pH (if the initial soil pH is too high (>9.5), it may lead to functional death after subsequent application; after settling, the soil pH can be reduced to 8-9, which is the optimal range for urease activity). After applying the remediation reaction solution, the previously applied desulfurized gypsum slurry has already lowered the soil pH and increased soil porosity, making it easier for bacteria to colonize the surface of soil particles. The bacteria secrete urease, which hydrolyzes urea to produce... and Microorganisms utilize the calcium source in desulfurized gypsum slurry and the carbonate ions produced by urea hydrolysis to induce the formation of calcite-type calcium carbonate precipitates in soil pores. They also simultaneously solidify heavy metal ions in the soil through co-precipitation and isomorphic substitution, thereby achieving the remediation of pre-modified soil.

[0014] The above process can be represented by the following chemical reaction formula: Ion exchange is performed by applying desulfurized gypsum slurry:

[0015] Urea hydrolysis:

[0016] Calcium carbonate precipitation and heavy metal fixation:

[0017] in, This represents a divalent metal cation, which can co-precipitate with calcium carbonate, and has an ionic radius close to... Heavy metal ions (e.g.) , , , and ) can be Isomorphic substitution, or inclusion through penetration into the gaps or defects of the crystal. Within the crystal lattice, heavy metals transform from soluble ions into insoluble forms, preventing their re-release into the environment. Furthermore, this immobilization form, supported by calcium carbonate, is insensitive to changes in the redox potential of the surrounding environment, thus enabling efficient heavy metal immobilization and maintaining long-term stability. The cell walls of functional mineralizing bacteria carry negative charges (carboxyl and phosphate groups), allowing them to adsorb positively charged metal ions like magnets. These adsorbed ions subsequently become nucleation sites for calcium carbonate crystal growth.

[0018] In one embodiment of the present invention, the mineralizing bacteria preparation component 20 includes: In enrichment culture unit 21, desulfurized gypsum powder is used as the initial bacterial source and inoculated into an enrichment culture medium with urea as the sole nitrogen source to obtain a primary enrichment solution. The domestication culture unit 22 is connected to the enrichment culture unit 21. The primary enrichment solution is subcultured in a domestication culture medium containing desulfurized gypsum extract to obtain desulfurized gypsum source functional mineralizing bacterial solution.

[0019] In this embodiment, the enrichment medium is prepared as follows: Weigh 5g of soybean peptone, 15g of casein peptone, 5g of sodium chloride, and 20g of urea (as the sole nitrogen source). Add 900g of distilled water, stir well, and adjust the pH to between 7 and 8. Sterilize the prepared enrichment medium at 120℃ for 15 minutes under 0.1MPa, and then add 20g of urea as the sole nitrogen source. If urea is added before sterilization, a low-temperature sterilization method is used to prevent urea decomposition at high temperatures. Select 10g of desulfurized gypsum powder dried at 60℃, and inoculate it into a conical flask containing 100mL of the above enrichment medium through enrichment culture unit 21. Incubate at 30℃ and 150rpm for 24-48 hours with shaking to obtain the primary enrichment solution. Select 1 mL of primary enrichment solution and inoculate it into fresh acclimatization medium at a ratio of 1:50 through acclimatization culture unit 22 (the composition of the acclimatization medium is the same as that of the enrichment medium, and 1% desulfurized gypsum extract can be added to enhance the strain's tolerance to heavy metals). Perform subculture (preferably 2-3 consecutive subcultures) to obtain a composite functional bacterial solution with stable genetic traits and high metabolic activity. When the culture solution becomes turbid, with obvious precipitation and a strong, pungent ammonia odor (indicating that urea has decomposed to produce ammonia gas), and the pH value rises significantly (>8.5), it indicates that the activation and acclimatization of the desulfurized gypsum-derived functional mineralizing bacteria have been successful.

[0020] In one embodiment of the present invention, the mineralizing bacteria preparation assembly 20 further includes an extract preparation unit 23, and the pulverizing device 11 further includes a third outlet; the extract preparation unit 23 includes: The extraction liquid mixing tank 231 is connected to the third outlet of the crushing device 11. It is used to receive the third part of desulfurized gypsum powder and mix the desulfurized gypsum powder with deionized water according to a preset mass ratio to obtain the extraction liquid. The first shaking incubator 232 and the extraction solution mixing tank 231 are set inside the first shaking incubator 232. The first shaking incubator 232 is used to perform a first shaking treatment on the extraction solution to obtain a shaking solution. Solid-liquid separation device 233 is used to perform solid-liquid separation treatment on the shaken mixture and extract the supernatant as desulfurized gypsum extract. The desulfurized gypsum extract includes calcium ions and sulfate ions dissolved from the desulfurized gypsum, as well as at least one target heavy metal pollutant ion dissolved from the impurities in the desulfurized gypsum.

[0021] In this embodiment, desulfurized gypsum produced by a coal-fired power plant is dried and pulverized to a predetermined fineness by a pulverizing device 11. A certain amount of desulfurized gypsum powder is weighed and placed in a clean container (extraction mixing tank 231). Deionized water is added according to a preset solid-liquid mass ratio, and the powder is stirred to initially disperse it. The mixture is transferred to a first shaking incubator 232 and continuously shaken at a set temperature and shaking speed for a predetermined time to fully leach out the soluble components in the desulfurized gypsum, resulting in a uniform shaking mixture. After the shaking treatment, the shaking mixture is separated into solid and liquid components by a solid-liquid separation device 233 to remove solid residues. The supernatant is collected and further filtered and sterilized to obtain a desulfurized gypsum extract. This extract contains calcium and sulfate ions dissolved from the desulfurized gypsum, as well as one or more target heavy metal pollutant ions dissolved from the impurities contained in the desulfurized gypsum.

[0022] In one embodiment of the present invention, the preset mass ratio of desulfurized gypsum powder to deionized water is 1:(5-20); The temperature conditions for the first oscillation process are: The rotation speed is not less than 100 rpm, and the first oscillation treatment time is... Hour.

[0023] In this embodiment, when preparing the desulfurized gypsum extract, the mass ratio of desulfurized gypsum powder to deionized water is controlled between 1:5 and 1:20. If the mass ratio is lower than 1:5, the system will become too thick and difficult to mix; if the mass ratio is higher than 1:20, the extract concentration will be insufficient to provide effective microbial acclimation pressure. The extraction process is underway... Oscillation under conditions of speed ≥100rpm Hours. This temperature range ensures efficient dissolution and energy saving, while sufficient rotation speed prevents powder deposition and ensures adequate contact; Hours of oscillation allow the target ions to fully dissolve and reach a stable state.

[0024] In one embodiment of the present invention, the domestication and cultivation unit 22 includes: Acclimation culture tank 221 is used to hold acclimation culture medium; The first metering inoculation tube 222 is connected between the enrichment culture unit 21 and the acclimatization culture tank 221, and is used to inoculate the primary enrichment solution into the acclimatization culture medium. The volume of the primary enrichment solution accounts for 1% to 3% of the total volume of the culture medium in the acclimatization culture tank 221. The extract addition device 223 includes a storage tank and a second metering inoculation tube. The storage tank is used to store the desulfurized gypsum extract, and the second metering inoculation tube is used to add the desulfurized gypsum extract to the acclimatization culture tank 221 at a ratio of 0.5% to 2.0% of the acclimatization culture medium volume. The second shaking incubator 224 is used to place the acclimatization culture tank 221 and to perform a second shaking treatment on the acclimatization culture medium under a preset temperature environment.

[0025] In this embodiment, after obtaining the primary enrichment solution, 1 mL of the primary enrichment solution is selected through the first metering inoculation tube 222 and inoculated into fresh acclimatization culture medium at a ratio of 1:50. The acclimatization culture medium is placed in the acclimatization culture tank 221, and the composition of the acclimatization culture medium is the same as that of the enrichment culture medium. An additional 1% of desulfurized gypsum extract is added to the acclimatization culture medium through the extract addition device 223 to enhance the strain's tolerance to heavy metals. The acclimatization culture medium with added desulfurized gypsum extract is placed in the second shaking incubator 224 and subjected to a second shaking treatment at a preset temperature. Two to three subcultures of acclimatization culture are performed to obtain a composite functional bacterial solution with stable genetic traits and high metabolic activity.

[0026] In one embodiment of the present invention, the optical density value of the desulfurized gypsum-derived functional mineralizing bacterial solution at a wavelength of 600 nm is between 1.0 and 1.5, and the urease activity of the desulfurized gypsum-derived functional mineralizing bacterial solution is between 10 and 15 U / mL.

[0027] In this embodiment, a spectrophotometer was used to measure the bacterial concentration. The optical density of the desulfurized gypsum-derived functional mineralizing bacterial solution at a wavelength of 600 nm needed to be controlled at approximately 1.0-1.5 to ensure sufficient bacterial biomass. A conductivity meter was used to detect urease activity. By measuring the rate of change in the conductivity of the bacterial solution, the urease activity was controlled at 10-15 U / mL (or the conductivity change was controlled within a specific range) to ensure the catalytic efficiency of the subsequent MIP reaction.

[0028] In one embodiment of the present invention, the target heavy metal ions include one or more of cadmium ions, lead ions, copper ions, and zinc ions.

[0029] In this embodiment, the method of the present invention is applicable to the remediation of common heavy metal pollution in soil, including ions corresponding to elements such as cadmium, lead, copper, and zinc. These ions can be simulated by desulfurized gypsum extract and effectively immobilized during subsequent microbial mineralization. The soil remediation method disclosed in this invention can simultaneously treat one or more of these heavy metal ions.

[0030] In one embodiment of the present invention, the particle size of the desulfurized gypsum powder is less than or equal to 0.075 mm; The mass ratio of desulfurized gypsum powder to water in the desulfurized gypsum slurry is 1:(4-6).

[0031] In this embodiment, desulfurization gypsum (the main component of which is produced by a coal-fired power plant) is selected. The desulfurized gypsum (with a moisture content of approximately 10-15%) is placed in a drying device (forced air drying oven) and dried at 60℃±5℃ for 12-24 hours (to remove surface free water and prevent dehydration and phase inversion of dihydrate gypsum). It is then pulverized using a ball mill or pulverizer and passed through a 200-mesh standard sieve with a diameter of 0.075mm, collecting the powder that passes through the sieve. This powder is mixed with water at a mass ratio of 1:(4-6) (preferably 1:5), and mechanically stirred for 30 minutes to prepare a uniformly suspended desulfurized gypsum slurry with a solid content of 15%-25% (preferably 20%).

[0032] In one embodiment of the present invention, the concentration of the urea solution is 18-22 g / L and the pH value is 7.0-8.0.

[0033] In this embodiment, a urea solution with a molar concentration of 18-22 g / L (preferably 20 g / L) is prepared, and the pH value is adjusted to 7-8 (this can be achieved by adding a small amount of urea solution). (Solution adjustment). The effect of urea concentration includes: if the urea concentration is too high, the excessively high concentration of urea will be rapidly hydrolyzed by urease, releasing a large amount of... This leads to a sharp increase in soil pH, inhibiting bacterial activity; if the urea concentration is too low, Insufficient urea concentration leads to low calcite precipitation, preventing heavy metal fixation via co-precipitation and significantly reducing fixation efficiency. This inhibits bacterial growth and urease activity, and the low urea concentration cannot support long-term remediation needs. A urea concentration of 20 g / L optimally matches bacterial growth and urease activity, achieving the highest heavy metal fixation efficiency while avoiding a balance between substrate limitation and toxicity inhibition.

[0034] In one embodiment of the present invention, the volume ratio of desulfurized gypsum-derived functional mineralizing bacteria solution to urea solution in the repair reaction solution is 1:1.

[0035] In this embodiment, the functional mineralizing bacteria solution and urea solution are mixed at a 1:1 ratio and then uniformly applied to the contaminated soil. The soil is then tilled again to ensure even distribution of the liquid. This ensures that the microbial activity matches the urea hydrolysis rate, providing sufficient carbonate ions for the precipitation reaction while avoiding a sharp increase in pH due to excessively high local urea concentrations, which would inhibit bacterial activity. The reaction solution prepared in this ratio exhibits good reaction stability and heavy metal fixation efficiency.

[0036] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0037] Finally, it should be noted that the above are merely preferred embodiments of the present invention, used only to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A soil remediation system based on the synergistic effect of desulfurized gypsum and microorganisms, characterized in that, include: A desulfurized gypsum treatment component includes a crushing device and a first mixing tank. The crushing device includes a first outlet and a second outlet for crushing desulfurized gypsum produced by a coal-fired power plant to obtain desulfurized gypsum powder. The first mixing tank is connected to the first outlet of the crushing device and is used to receive a first portion of the desulfurized gypsum powder and to mix the desulfurized gypsum powder with water to obtain a desulfurized gypsum slurry. The mineralizing bacteria preparation component is connected to the second outlet of the pulverizing device and is used to receive the second part of desulfurized gypsum powder. The desulfurized gypsum powder is used as the initial bacterial source and inoculated into a prepared enrichment culture medium for enrichment culture and subculture to obtain desulfurized gypsum source functional mineralizing bacteria solution. The nitrogen source in the enrichment culture medium is urea. The first spraying component is connected to the first mixing tank and is used to spray the desulfurized gypsum slurry onto the soil to be remediated. The second mixing tank is connected to the mineralization bacteria preparation component and is used to mix the desulfurized gypsum source functional mineralization bacteria liquid with urea solution to obtain a repair reaction solution. The soil tillage component is used to tillage the soil to be repaired after the spraying component applies desulfurized gypsum slurry to the soil to be repaired, so as to mix the soil to be repaired with the desulfurized gypsum slurry evenly and obtain pre-improved soil. In addition, the soil to which the remediation reaction solution has been applied is tilled to precipitate the target heavy metal ions in the soil and thus remediate the soil.

2. The system according to claim 1, characterized in that, The mineralization bacteria preparation component includes: In the enrichment culture unit, the desulfurized gypsum powder is used as the initial bacterial source and inoculated into an enrichment culture medium with urea as the sole nitrogen source to obtain a primary enrichment solution. An acclimatization culture unit, connected to the enrichment culture unit, is used to subculture the primary enrichment solution in an acclimatization culture medium containing desulfurized gypsum extract to obtain a desulfurized gypsum-derived functional mineralizing bacterial solution.

3. The system according to claim 2, characterized in that, The mineralizing bacteria preparation assembly further includes an extract preparation unit, and the pulverizing device further includes a third outlet; the extract preparation unit includes: The extraction solution mixing tank is connected to the third outlet of the pulverizing device. It is used to receive the third part of desulfurized gypsum powder and mix the desulfurized gypsum powder with deionized water according to a preset mass ratio to obtain the extraction solution. The first shaking incubator is used to perform a first shaking treatment on the extract mixture to be extracted, so as to obtain a shaking mixture. A solid-liquid separation device is used to perform solid-liquid separation treatment on the shaken mixture and extract the supernatant as a desulfurized gypsum extract. The desulfurized gypsum extract includes calcium ions and sulfate ions dissolved from the desulfurized gypsum, as well as at least one target heavy metal pollutant ion dissolved from impurities in the desulfurized gypsum.

4. The system according to claim 3, characterized in that, The preset mass ratio of the desulfurized gypsum powder to deionized water is 1:(5-20); The temperature conditions for the first oscillation treatment are 20-30℃, the rotation speed is not less than 100rpm, and the time for the first oscillation treatment is 12-48 hours.

5. The system according to claim 2, characterized in that, The domestication and cultivation unit includes: An acclimatization culture tank is used to hold the acclimatization culture medium; A first metering inoculation tube is connected between the enrichment culture unit and the acclimatization culture tank, and is used to inoculate the primary enrichment solution into the acclimatization culture medium, wherein the volume of the primary enrichment solution accounts for 1% to 3% of the total volume of the culture medium in the acclimatization culture tank; An extract addition device includes a storage tank and a second metering inoculation tube. The storage tank is used to store desulfurized gypsum extract, and the second metering inoculation tube is used to add the desulfurized gypsum extract to the acclimatization culture tank at a ratio of 0.5% to 2.0% of the volume of the acclimatization culture medium. The second shaking incubator is used to place the acclimatization culture tank and to perform a second shaking treatment on the acclimatization culture medium under a preset temperature environment.

6. The system according to claim 3, characterized in that, The optical density value of the desulfurized gypsum-derived functional mineralizing bacterial solution at a wavelength of 600 nm is between 1.0 and 1.5, and the urease activity of the desulfurized gypsum-derived functional mineralizing bacterial solution is between 10 and 15 U / mL.

7. The system according to claim 1, characterized in that, The target heavy metal ions include one or more of cadmium ions, lead ions, copper ions, and zinc ions.

8. The system according to claim 1, characterized in that, The particle size of the desulfurized gypsum powder is less than or equal to 0.075 mm; The mass ratio of desulfurized gypsum powder to water in the desulfurized gypsum slurry is 1:(4-6).

9. The system according to claim 1, characterized in that, The concentration of the urea solution is 18-22 g / L, and the pH value is 7.0-8.

0.

10. The system according to claim 1, characterized in that, The volume ratio of the desulfurized gypsum-derived functional mineralizing bacteria solution to the urea solution in the repair reaction solution is 1:1.

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