Method for preparing ecological remediation soil by using microbial remediation of contaminated spoil

Abstract

The application discloses a method for preparing ecological restoration soil by repairing contaminated spoil through regeneration, and comprises the following steps: mixing dry straw powder and bimetallic alkali liquor, stirring and drying, pyrolyzing under a protective atmosphere at a temperature above 500 DEG C to obtain modified biochar material; mixing the modified biochar material with microbial liquid, oscillating and adsorbing, and freeze-drying to obtain carbon-based biological composite material; mixing the carbon-based biological composite material with shield spoil to obtain improved shield spoil; and mixing the improved shield spoil with organic fertilizer to obtain ecological restoration soil; the method removes toxic and harmful components in the shield spoil through biodegradation, the modified biochar improves the structure of the shield spoil, and the specific component compound fertilizer is used, so that the shield spoil is recycled, and the shield spoil-based ecological restoration soil is obtained.

Description

Technical Field

[0001] This invention belongs to the field of solid waste utilization technology, specifically relating to a method for preparing ecological restoration soil by regenerating contaminated slag using microorganisms. Background Technology

[0002] The rapid development of urban rail transit, especially the construction of subway lines, is inseparable from tunnel boring machine (TBM) technology. TBM construction boasts advantages such as high construction speed, high safety, and minimal impact on surface traffic, making it one of the main technical means for urban underground engineering construction. However, with the continuous improvement of TBM technology, additives, primarily surfactants such as foaming agents and dispersants, are inevitably incorporated to enhance tunneling efficiency. This generates a large amount of biotoxic tunnel boring machine (TBM) waste soil each year, posing new challenges to the urban ecological environment and land resources. Faced with increasingly serious environmental pollution, instability risks, and land occupation, open-air dumping and landfilling are no longer suitable disposal methods. Therefore, the safe treatment and disposal (pollutant reduction, structural improvement) and resource utilization (ecological restoration applications) of TBM waste soil are urgent engineering challenges that need to be addressed at present.

[0003] Meanwhile, the study found that when tunnel boring machine (TBM) slag is used for plant growth and planting, it has many defects and limitations, such as insufficient nutrient content, low soil biological activity, and unstable physicochemical properties. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing ecological restoration soil by regenerating contaminated tunnel boring machine (TBM) slag using microbial remediation. This method removes toxic and harmful components from TBM slag through biodegradation and then combines it with a compound fertilizer containing specific components to achieve the resource utilization of TBM slag and obtain TBM slag-based ecological restoration soil.

[0005] To achieve the above objectives, the following technical solution is adopted:

[0006] A method for preparing ecological restoration soil by regenerating contaminated waste using microorganisms includes the following steps:

[0007] (1) After mixing dried straw powder with bimetallic alkali solution, the mixture is matured and then pyrolyzed at a temperature above 500°C under a protective atmosphere to obtain modified biochar material.

[0008] (2) The modified biochar material is mixed with microbial inoculum, shaken for adsorption, and freeze-dried to obtain a carbon-based biocomposite material;

[0009] (3) The carbon-based biocomposite material is mixed with shield tunneling slag to obtain improved shield tunneling slag;

[0010] (4) Mix the improved shield tunnel slag with organic fertilizer to obtain soil for ecological restoration.

[0011] According to the above scheme, the dried straw powder in step 1 is soaked in deionized water, washed, and dried.

[0012] According to the above scheme, the bimetallic alkaline solution in step 1 is prepared by mixing FeCl3 and Mg(OH)2 in NaOH solution at a molar ratio of 1:2, with a pH of 8-10, wherein Fe... 3+ The solution concentration is 1 mol / L.

[0013] According to the above scheme, in step 1, the dried straw powder and bimetallic alkali solution are mixed at a solid-liquid ratio of 1:10 g / mL, heated to 60-80℃, and the maturation time is 10h.

[0014] According to the above scheme, the pyrolysis process in step 1 is carried out in a quartz tube furnace, with N2 protective gas flowing through it, a heating rate of 10℃ / min, and pyrolysis for 2 hours.

[0015] According to the above scheme, the microbial inoculum in step 2 is prepared in the following way:

[0016] Obtain the types and concentrations of anionic surfactants in the shield tunnel slag, including but not limited to one or more of the common shield tunnel slag foaming agents, such as sodium dodecyl sulfate (SDS), sodium fatty alcohol polyoxyethylene ether sulfate (AES), and α-alkenyl sulfonate (AOS); and prepare an inorganic salt culture medium using one or more anionic surfactants as the sole carbon source.

[0017] Microbial cells were extracted from the sedimentation and separation of activated sludge samples produced by wastewater treatment plants, and washed three times by resuspending in sterile phosphate buffer solution. The precipitated solid portion was then inoculated into the culture medium and cultured at 30°C and 180 rpm for 7 days to obtain the inoculum.

[0018] The inoculum was added to the new culture medium at a 5% inoculum amount. The concentration of anionic surfactant in the culture medium was increased generation by generation to screen and enrich bacterial groups. The culture was carried out at 30°C and 180 rpm for 3 days. The culture was repeated 3 times to obtain the target bacterial culture that efficiently degrades anionic surfactants.

[0019] According to the above scheme, the microbial culture in step 2 uses a mixed culture containing Pseudomonas, Klebsiella, *Xanthomonas humanis*, and *Neorhizium anisopliae*, with an OD of [missing information]. 600 If the value is >0.8, add 5 VT% of bacterial solution to the culture medium and mix it with modified biochar material at a solid-liquid ratio of 1:100 mg / mL.

[0020] According to the above scheme, the leaching amount of anionic surfactant in the improved shield tunnel slag in step 3 is less than 0.3 mg / L.

[0021] According to the above scheme, in step 3, the carbon-based biocomposite material is activated at 30°C and 180 rpm for 48 hours before being mixed with the shield tunneling slag.

[0022] According to the above scheme, in step 3, the carbon-based biocomposite material is mixed with the shield tunneling slag at a mass ratio of 1:50.

[0023] According to the above scheme, the composition of the organic fertilizer in step 4, by weight, is as follows:

[0024] 30-50 parts modified sludge, 5-10 parts modified red mud, and 10-20 parts mixed biological crust;

[0025] According to the above scheme, the modified sludge is prepared in the following manner:

[0026] Ozone micro-nano bubbles are injected into the sludge for oxidation treatment. The ozone dosage is 0.1-0.2 g / g of sludge, and the reaction time is 20-30 min. The sludge comes from an urban sewage treatment plant and contains organic matter, nitrogen, and phosphorus.

[0027] According to the above scheme, the modified red mud is prepared in the following manner:

[0028] The pH of the red mud was adjusted to 6.5-7.5 using 30-50 wt% phosphoric acid as a neutralizing agent, and then washed and separated to obtain modified red mud.

[0029] According to the above scheme, the hybrid biological crust is prepared in the following manner:

[0030] Mix 50-70 parts by weight of algae-lichen type biocrust, 1-5 parts of microbial inoculant, 10-20 parts of HEPES buffer, and 5-10 parts of gum arabic binder. Incubate for 3-5 days at a temperature of 25-30℃ and a humidity of 60-80% with 8-12 hours of light per day. Remove excess water to obtain a stable mixed biocrust. The microbial inoculant consists of rhizobium, Bacillus subtilis, and Pseudomonas aeruginosa.

[0031] According to the above scheme, the amount of organic fertilizer added in step 4 is 5-10 wt%.

[0032] Carbon-based biomaterials can effectively reduce pollutants in tunnel boring machine (TBM) excavation while improving soil properties. Specifically, the selected target microorganisms can be widely used to degrade surfactant-based pollutants, offering advantages such as low carbon footprint, low cost, and environmental sustainability. Biochar itself has the functions of adsorbing pollutants and enhancing soil mechanical properties, making it widely used in environmental, geotechnical, and agricultural fields. The degradation performance of the target microorganisms can compensate for the limitation of biochar in completely eliminating pollutants, while the addition of biochar provides a favorable survival carrier for microorganisms and improves soil aggregate structure.

[0033] Ecological restoration soil prepared by modifying tunnel boring machine (TBM) slag using carbon-based biomaterials should be combined with organic fertilizers for vegetative application to optimize the microbial community structure and diversity. Solid waste-based bio-crust type compound organic fertilizer is a technical formula that uses sludge and red mud as solid waste components and mixed bio-crust as an auxiliary material. Sludge is rich in organic matter, nitrogen, phosphorus, potassium, and other nutrients, while red mud contains minerals such as iron, aluminum, and silicon. The synergistic effect of sludge and red mud can replenish trace elements in the soil and improve soil water retention and aeration. The mixed bio-crust is rich in algae, lichens, mosses, and microorganisms, including nitrogen-fixing bacteria, potassium-solubilizing bacteria, and phosphate-solubilizing bacteria, which are beneficial for nutrient cycling, improve soil nutrient availability, and promote plant establishment and growth.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] The carbon-based biomaterial used as a soil conditioner for the ecological restoration of tunnel boring machine (TBM) slag soil in this invention comprises highly efficient degrading bacteria loaded onto modified biochar. These highly efficient degrading bacteria are widely applicable to the degradation of surfactant-based pollutants. The modified biochar not only serves as a favorable carrier for biomass but also adsorbs pollutants, improves soil aggregate structure, and enhances soil mechanical properties. This carbon-based biomaterial can synergistically improve the structure and reduce pollution in TBM slag soil, decreasing the bioavailability and mobility of pollutants in the soil and reducing their harm to plants and soil ecosystems.

[0036] This invention combines shield tunnel slag-based ecological restoration soil and solid waste-based bio-crust type compound organic fertilizer to prepare ecological restoration soil. The solid waste-based bio-crust type compound organic fertilizer contains sludge rich in organic matter, nitrogen, phosphorus, potassium and other nutrients, and red mud containing minerals such as iron, aluminum, and silicon. The synergistic effect of sludge and red mud can supplement the trace elements in the soil and improve the soil's water retention and aeration. The mixed bio-crust is rich in algae, lichens and microorganisms, which can optimize the community structure and diversity of microorganisms. These microorganisms, including nitrogen-fixing bacteria, potassium-solubilizing bacteria and phosphorus-solubilizing bacteria, are conducive to nutrient cycling, improve the soil's nutrient availability, and facilitate the continuous and slow supply of nutrients to plants, promoting plant establishment and growth. Attached Figure Description

[0037] Figure 1 A method for improving tunnel boring machine excavation soil using carbon-based biocomposite materials.

[0038] Figure 2 A method for obtaining soil for ecological restoration by using modified shield tunneling slag and compound organic fertilizer. Detailed Implementation

[0039] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0040] A specific embodiment provides a microbial bacterial solution:

[0041] Prepare an inorganic salt culture medium using AS as the sole carbon source, including 3.67 g / L inorganic salt basal medium (Chinook, catalog number CN230590), 0.5 g / L... EDTA-disodium (Phygene, catalog number PH9041) was used to prepare AS standard solutions at concentration gradients of 100, 200, 500, 600, 800, 1000, and 1200 mg / L. Microbial cells were extracted from activated sludge samples and centrifuged at 3000 rpm to obtain precipitated microbial cells. These cells were then resuspended and washed three times with sterile phosphate-buffered saline (PBS) (Biosharp, catalog number BL601A). The precipitated solids were inoculated into a container containing AS culture medium and cultured on a shaker at 180 rpm and 30°C for 7 days to obtain the inoculum. The inoculum was then added to new AS culture medium at a 5% inoculum volume and cultured on a shaker at 180 rpm and 30°C for 3 days. The concentration of AS culture medium was progressively increased for screening and enrichment. After five consecutive subcultures, a microbial culture with highly efficient AS degradation capabilities was obtained.

[0042] A specific implementation provides a hybrid type of biological crust:

[0043] Mature algal-lichen biocrusts were collected, naturally air-dried or dried at below 40℃, pulverized, and sieved to a particle size of less than 0.15mm. Purchased rhizobium (Rhizobium cellulosilyticum, CGMCC 1.15995), Bacillus subtilis (CGMCC 1.3358), and Pseudomonas guguanensis (CGMCC 1.15627) were cultured at a ratio of 1–2:5–6:2–3. The resulting microbial inoculum was concentrated by centrifugation or filtration, ensuring a viable count of 3 × 10⁻⁶ cells / year. 9 CFU / g; Prepare a 20mM HEPES buffer solution and adjust the pH to approximately 6.5-7.5 with 0.5-1M NaOH. Prepare a 5-10% gum arabic binder solution, filter and sterilize it, and use it as an excipient. Mix thoroughly for 10-20 minutes according to the following ratio: algae-lichen type biocrust 50-70, microbial agent 1-5, HEPES buffer 10-20, gum arabic binder 5-10. Incubate for 3-5 days at a temperature of 25-30℃ and a humidity of 60-80% with 8-12 hours of light per day. Remove excess water to form a stable mixed biocrust.

[0044] A specific embodiment provides a solid waste-based biocrust type compound organic fertilizer, which uses modified sludge and modified red mud as solid waste-based components and mixed biocrust as auxiliary material. The compound organic fertilizer, calculated by dry weight, contains 30-50 parts of modified sludge, 5-10 parts of modified red mud, and 10-20 parts of mixed biocrust.

[0045] Specifically, the preparation conditions for the modified sludge include: injecting ozone micro-nano bubbles into the sludge for oxidation treatment, with an ozone dosage of 0.1–0.2 g / g, an air intake rate of 1.8–2.0 L / min, and a reaction time of 20–30 min.

[0046] Specifically, the preparation conditions of the modified red mud include: adjusting the pH of the red mud with 30-50 wt% phosphoric acid as a neutralizing agent, and then washing and separating it.

[0047] The specific implementation method provides a method for preparing ecological restoration soil by regenerating contaminated waste soil using microbial remediation:

[0048] (1) After sieving the straw powder, soak and wash the straw powder with deionized water to remove excess soluble salt impurities, and dry it for 24 hours before sealing and storing it. Mix the dried straw powder with bimetallic alkali solution at a solid-liquid ratio of 1:10 (g / mL) at room temperature for 30 minutes. The bimetallic alkali solution is prepared by FeCl3·6H2O and Mg(OH)2 in a molar ratio of 1:2. Place them together in a magnetic stirrer at 60-80℃ for 10 hours and adjust the pH to 8-10 with NaOH solution. Recover the solid phase components by high-speed centrifugation at 8000rpm for 10 minutes and wash with deionized water 3 times. Dry the material in an oven at 105℃ for 24 hours. Heat the dried material to 500℃ in a quartz tube furnace at a rate of 10℃ / min and keep it at a constant temperature for 2 hours. Use N2 protective gas with a flow rate of 100mL / min throughout the process to obtain modified biochar material.

[0049] (2) The modified biochar material was mixed with the above-mentioned microbial liquid, and the mixture was shaken and adsorbed at 180 rpm and 30°C for 12 h. After filtering the mixed suspension, it was washed three times with PBS and freeze-dried to obtain the carbon-based biocomposite material, which was stored at 4°C for later use.

[0050] (3) The carbon-based biocomposite material is activated in a culture medium at 30°C and 180 rpm for 48 hours, and then uniformly sprayed into the shield tunnel slag (the mass ratio of the two is 1:50). During the spraying process, the material flow rate and uniformity are controlled to avoid local concentrations that are too high or too low. After spraying, the material is stirred a second time to ensure that the material and the shield tunnel slag are fully mixed to prepare the improved shield tunnel slag. The concentration of anionic surfactant leaching in the improved shield tunnel slag-based ecological restoration soil meets the requirement of groundwater and surface water environmental quality standards <0.3 mg / L.

[0051] (4) Add 5-10 wt% solid waste-based biological crust-type compound organic fertilizer to the improved shield tunnel slag to make ecological restoration soil, and lay it on the surface of mine wounds, green land, etc., with a thickness of 50-60 cm; native plants adapted to the local environment, herbaceous plants, shrubs and trees, etc. can be selected for planting.

[0052] This application provides a method for improving shield tunneling slag with carbon-based biocomposite materials, as detailed in the attached document. Figure 1 As shown, this method loads highly efficient degrading microbial communities onto modified biochar via physical adsorption and immobilization. The synthesized carbon-based biocomposite material can compensate for the deficiency of biochar in completely eliminating pollutants through the degradation performance of the target microorganisms, and has the advantages of low carbon, low cost, and environmental sustainability. The addition of biochar can also provide a favorable survival carrier for microorganisms, which can enhance soil mechanical properties, increase soil porosity, improve soil aeration and permeability, and improve soil aggregate structure while adsorbing pollutants.

[0053] Microbial concentrate was extracted from activated sludge, and the concentration of the AS culture medium was progressively increased to screen and enrich the microorganisms, obtaining a highly efficient target bacterial culture (S1) for degrading AS. This step included obtaining different formulations of tunnel boring machine (TBM) agents used in different construction projects and the dosage of anionic surfactants in those formulations; diluting the TBM agents to the required target pollutant concentration of 100–1200 mg / L; preparing an inorganic salt culture medium with AS as the sole carbon source; extracting activated sludge samples from wastewater treatment plants and centrifuging at 3000 rpm to obtain precipitated microbial cells; resuspending and washing three times with sterile phosphate buffer solution; inoculating the precipitated solid portion into a container containing AS culture medium and culturing at 30°C and 180 rpm for 7 days to obtain the inoculum; adding the inoculum to new AS culture medium at a 5% inoculum volume and culturing at 30°C and 180 rpm for 3 days; progressively increasing the concentration of the AS culture medium to screen and enrich the bacterial population; and continuously subculturing three times to obtain a highly efficient target bacterial culture for degrading the anionic surfactant AS.

[0054] It is understandable that the anionic surfactants in the tunnel boring machine's chemicals have a similar effect to Ca. 2+ Mg 2+The ability of metal ions to form turbid complexes affects subsequent observation of the OD600 value of the bacterial community in the culture medium. Therefore, when using 3.67 g / L inorganic salt basal medium (Chinook, catalog number CN230590), 0.5 g / L EDTA-disodium (Phygene, catalog number PH9041) was used in conjunction to ensure that the OD value of the medium was not affected by the target contaminant itself after adding different concentrations of AS. Anionic surfactants are easily decomposed at high temperatures. After sterilizing the inorganic salt basal medium and EDTA-disodium at 121°C under high pressure, the sterilized anionic surfactant solution was filtered through a 0.22 μm PES filter membrane to obtain AS culture solutions of 100, 200, 500, 600, 800, 1000, and 1200 mg / L. Washing the inoculum extracted from activated sludge with sterile phosphate-buffered saline (PBS) (Biosharp, catalog number BL601A) can stabilize the pH of the microbial environment within a certain range, thus prolonging the growth and reproduction of the microorganisms.

[0055] The preparation process is described below according to different implementation methods:

[0056] Example 1

[0057] The formulation of the shield tunneling agent used in a certain construction project contained 1.4% sodium dodecyl sulfate (SDS), 3.2% α-alkenyl sulfonate (AOS), 1.6% sodium dodecylbenzene sulfonate (SDBS), and 2.3% sodium fatty alcohol polyoxyethylene ether sulfate (AES). After dilution, it was mixed with 3.67 g / L of inorganic salt medium and 0.5 g / L of EDTA-disodium to prepare culture solutions with AS as the sole carbon source at concentrations of 100, 200, 500, 600, 800, 1000, and 1200 mg / L, respectively. Activated sludge samples were resuspended in sterile phosphate buffer solution and washed three times, then centrifuged at 3000 rpm to obtain precipitated microbial cells. The precipitated solid fraction was inoculated into AS culture medium and cultured at 30°C and 180 rpm for 7 days to obtain the inoculum. The inoculum was added at a 5% inoculum volume to a new culture medium to increase the AS concentration, and cultured at 30°C and 180 rpm for 3 days. This was repeated three times, and the target bacterial culture for highly efficient degradation of the anionic surfactant AS was screened and enriched. Analysis showed that the mixed bacterial culture mainly contained Pseudomonas, Klebsiella, Luteibacter anthropi, and Neorhizobium. OD 600 Value > 0.8.

[0058] Example 2

[0059] The shield tunneling agent formulation used in a certain construction project contained 2.7% sodium dodecyl sulfate (SDS), 4.0% α-alkenyl sulfonate (AOS), and 6.4% sodium fatty alcohol polyoxyethylene ether sulfate (AES). After dilution, it was mixed with 3.67 g / L inorganic salt medium and 0.5 g / L EDTA-disodium to prepare culture solutions with AS as the sole carbon source at concentrations of 200, 500, 800, 1000, and 1200 mg / L, respectively. Activated sludge samples were resuspended in sterile phosphate buffer solution and washed three times, followed by centrifugation at 3000 rpm to obtain precipitated microbial cells. The precipitated solids were inoculated into AS culture solution and cultured at 30°C and 180 rpm for 7 days to obtain the inoculum. The inoculum was then added at a 5% inoculation rate to a new culture solution with increased AS concentration, and cultured at 30°C and 180 rpm for 3 days. This process was repeated three times, and the target bacterial culture for efficiently degrading the anionic surfactant AS was screened and enriched.

[0060] Modified biochar (S2) was obtained by co-carbonizing magnesium-iron bimetallic biochar using straw powder, FeCl3·6H2O, Mg(OH)2, and NaOH as raw materials. This step involved mixing dried straw powder with FeCl3·6H2O solution and Mg(OH)2 powder, adjusting the pH to alkaline with NaOH solution, and then co-carbonizing at 60–80℃ for 10 hours. After drying, magnesium-iron bimetallic modified straw powder material was obtained. The magnesium-iron bimetallic modified straw powder material was then carbonized and pyrolyzed at 500℃ for 2 hours in a quartz tube furnace under N2 protective gas to obtain magnesium-iron bimetallic modified biochar material.

[0061] Understandably, the type of straw powder that can be selected includes corn straw powder, peanut straw powder, rice straw powder, etc., and different types of straw powder will affect the properties of the biochar produced during subsequent carbonization. During the co-alkali ripening process of straw powder and bimetallic alkali solution, the alkali solution can penetrate into the interior of the straw powder and react with organic matter. Sufficient contact with biomass before carbonization can more effectively promote the decomposition and activation of biomass, forming more micropores and mesopores, and increasing the specific surface area of ​​the modified biochar.

[0062] Example 3

[0063] After selecting and sieving straw powder, it was soaked and washed with deionized water to remove excess soluble salt impurities. After drying for 24 hours, it was sealed and stored. The dried straw powder and bimetallic alkali solution were mixed evenly at room temperature for 30 minutes at a solid-liquid ratio of 1:10 (g / mL). The bimetallic alkali solution was prepared by mixing FeCl3·6H2O solution and Mg(OH)2 powder at a molar ratio of 1:2. The mixture was placed together in a magnetic stirrer at 70℃ for 10 hours and the pH was adjusted to within the range of 9 with NaOH solution. The solid phase components were recovered by high-speed centrifugation at 8000rpm for 10 minutes and washed three times with deionized water. The mixture was then dried in an oven at 105℃ for 24 hours. The dried material was then pyrolyzed in a quartz tube furnace at a rate of 10℃ / min to 500℃ for 2 hours under constant temperature with N2 protective gas at a flow rate of 100mL / min throughout the process to obtain modified biochar material.

[0064] A carbon-based biocomposite material (S3) was prepared by loading highly efficient degrading bacteria onto modified biochar via physical adsorption and immobilization. This step involves mixing and immobilizing the modified biochar, which was co-carbonized after bimetallic co-alkali ripening of straw powder, with the target bacterial solution containing highly efficient degrading anionic surfactant AS at a loading ratio of 1:200 (g / mL), thereby forming the carbon-based biocomposite material.

[0065] Understandably, the porous structure, abundant surface functional groups, and microbial activity of the synthesized carbon-based biocomposite material enable it to efficiently adsorb and degrade pollutants in the soil. At the same time, it also improves the soil aggregate structure, provides nutrients, promotes soil microbial activity, and regulates soil pH, thus improving the composition of tunnel boring machine slag.

[0066] Example 4

[0067] Centrifuge the cultured bacterial suspension at 4500 rpm for 5 min, remove the supernatant, and retain the solid bacterial cells. Wash the bacterial cells twice with 0.9% physiological saline, resuspending them after each centrifugation. Resuspend the washed bacterial cells in 0.9% physiological saline to prepare a homogeneous bacterial suspension, ensuring a viable count of 2.0 × 10⁻⁶. 9 CFU / mL (OD) 600 =1) Approximately. The pre-cleaned modified biochar material was mixed with 0.9% physiological saline and sterilized by high-temperature and high-pressure steam at 121℃ for 20 min. After filtration, 0.5 g of material with a particle size of 0.1–0.3 mm was sieved and transferred to 100 mL of the above bacterial suspension, and the mixture was kept at 30℃ and shaken at 180 rpm for 12 h. Before the bacterial growth curve reached its peak, the bacterial suspension in the conical flask was filtered through 2.5 μm (1–3 μm) Whatman No. 5 ashless filter paper for slow qualitative analysis, and washed three times with 0.1 M phosphate-buffered saline (PBS) (pH 7.4). The resulting carbon-based biocomposite material was freeze-dried and stored at 4℃ for later use.

[0068] The carbon-based biocomposite material is mixed with tunnel boring machine (TBM) slag at a mass ratio of 1:50 to obtain modified TBM slag (S4). This step includes naturally air-drying or mechanically drying the TBM slag below 60°C to remove excess moisture and prevent changes in soil properties due to high temperatures; screening the TBM slag using a vibrating screen to remove large particles and construction waste, obtaining soil particles with a diameter of less than 2 mm. The synthesized carbon-based biocomposite material is then pulverized and screened into particles with a diameter of less than 0.1 mm, and uniformly mixed with the TBM slag to prepare modified TBM slag with a moisture content of 20%.

[0069] Understandably, the concentration of anionic surfactants leached from the improved shield tunneling excavation soil meets the requirement of <0.3 mg / L for groundwater and surface water environmental quality standards. Through pollution reduction treatment and synergistic structural improvement, it possesses multiple functions, including reducing pollutants, improving soil structure, providing nutrients, promoting microbial activity, and regulating pH. Its application not only solves the environmental pollution problem of shield tunneling excavation soil but also provides an efficient and environmentally friendly solution for ecological restoration, demonstrating significant economic, social, and ecological benefits.

[0070] This application provides a method for obtaining ecological restoration soil by combining modified shield tunneling slag with solid waste-based bio-skin-type compound organic fertilizer, as shown in the attached document. Figure 2 As shown, this method uses sludge and red mud as substrate components, combined with collected algae-lichen type biocrusts to synthesize a solid waste-based biocrust-type compound organic fertilizer, which is rich in organic matter, nutrients, and microbial activity. Mixing the improved shield tunneling slag with this solid waste-based biocrust-type compound organic fertilizer not only improves the soil's physical structure but also effectively increases its biological activity, making it highly effective for use in abandoned sites, mining areas, and highway slopes. Based on soil improvement, planting suitable vegetation can fully utilize the soil's nutrients and microbial communities, promoting rapid plant growth and vegetation restoration.

[0071] Example 5

[0072] The tunnel boring machine (TBM) excavated soil from a certain construction project was naturally dried or mechanically dried at a temperature below 60°C to remove excess moisture, and then sieved through a 2mm vibrating screen to obtain soil particles. The carbon-based biocomposite material synthesized in Example 4 was crushed, sieved into particles with a particle size of less than 0.1mm, and mixed with the TBM excavated soil at a mass ratio of 1:50. Water was added to synthesize a 20% modified TBM excavated soil mixture.

[0073] The method includes the following steps: mixing 50-70g of algae-lichen biocrust, 1-5g of microbial inoculant, 10-20g of HEPES buffer, and 5-10g of gum arabic to obtain a mixed biocrust. This step includes collecting mature algae-lichen biocrust, drying, pulverizing, and sieving to obtain a dried biocrust material with a certain fertility; purchasing bacterial strains from a preservation center and expanding their cultivation to obtain a mixed microbial inoculant; preparing HEPES buffer (Biofroxx, catalog number 1112GR500) and gum arabic (Kermel, CAS number 9000-01-5) binder to a certain concentration, adjusting the pH to the range of 6.5-7.5, filtering, sterilizing, and obtaining the excipient.

[0074] It is understandable that mature algal-lichen biocrusts are rich in nutrients and organic matter required by plants, providing a favorable habitat for soil microorganisms and promoting their growth and reproduction. Adding mixed microbial agents facilitates the presence of specific microbial communities necessary for plant growth, thereby enhancing soil biodiversity and stability. HEPES buffer and gum arabic binder are used as excipients. On the one hand, HEPES buffer helps maintain soil pH stability by preventing the growth and reproduction of microorganisms from secreting acidic substances that could alter the soil's physicochemical properties. On the other hand, gum arabic binder, as a natural and renewable material, possesses excellent adhesion, film-forming properties, biocompatibility, and multifunctionality, effectively binding the dried algal-lichen biocrust with the microbial agents to form a stable mixed biocrust (S1).

[0075] Example 6

[0076] Mature algal-lichen-type biocrusts were collected, naturally sun-dried, or dried at below 40℃, then pulverized and sieved to a particle size of less than 0.15mm. Purchased rhizobium (Rhizobium cellulosilyticum, CGMCC 1.15995), Bacillus subtilis (CGMCC 1.3358), and Pseudomonas guguanensis (CGMCC 1.15627) were cultured in a 2:6:2 ratio, and concentrated by centrifugation or filtration to prepare a microbial inoculum, ensuring a viable count of 3×10⁻⁶. 9CFU / g; Prepare a 20mM HEPES buffer solution and adjust the pH to approximately 6.5-7.5 with 0.5-1M NaOH. Prepare a 5% gum arabic binder solution, filter and sterilize it, and use it as an excipient. Mix thoroughly for 10-20 minutes according to the following ratio: algae-lichen type biocrust 70, microbial agent 5, HEPES buffer 10, gum arabic binder 5. Incubate for 3-5 days at a temperature of 25-30℃ and a humidity of 60-80% with 8-12 hours of light per day. Remove excess water to form a stable mixed biocrust.

[0077] Example 7

[0078] Mature algal-lichen biocrusts were collected, naturally sun-dried or dried at below 40℃, and then pulverized and sieved to a particle size of less than 0.15mm. Purchased Rhizobium cellulosilyticum (CGMCC 1.15995), Bacillus subtilis (CGMCC 1.3358), and Pseudomonas guguanensis (CGMCC 1.15627) were cultured in a 2:5:3 ratio, and concentrated by centrifugation or filtration to prepare a microbial inoculum, ensuring a viable count of 3×10⁻⁶. 9 CFU / g; Prepare a 20mM HEPES buffer solution and adjust the pH to approximately 6.5-7.5 with 0.5-1M NaOH. Prepare a 10% gum arabic binder solution, filter and sterilize it, and use it as an excipient. Mix thoroughly for 10-20 minutes according to the following ratio: algae-lichen type biocrust 60, microbial agent 3, HEPES buffer 20, gum arabic binder 5. Incubate for 3-5 days at a temperature of 25-30℃ and a humidity of 60-80% with 8-12 hours of light per day. Remove excess water to form a stable mixed biocrust.

[0079] The mixed bio-crust (10-20g), sludge (30-50g), and red mud (5-10g) are mixed to obtain a solid waste-based bio-crust type compound organic fertilizer. This step includes injecting ozone micro-nano bubbles into the sludge for oxidation treatment, with an ozone dosage of 0.1-0.2g / g, an air intake rate of 1.8-2.0L / min, and a reaction time of 20-30min. The red mud is adjusted to pH using 30-50% phosphoric acid as a neutralizing agent and then washed and separated. After pretreatment such as drying, pulverizing, and sieving, the sludge, red mud, and mixed bio-crust are obtained as solid waste-based bio-crust type compound organic fertilizer (S2).

[0080] Understandably, injecting ozone micro-nano bubbles into sludge for oxidation treatment aims to utilize the strong oxidizing properties of ozone and the efficient mass transfer characteristics of micro-nano bubbles to oxidize, decompose, and remove organic matter, heavy metals, pathogens, and other pollutants from the sludge. This not only effectively reduces the water content of the sludge but also decreases harmful substances, improving its stability and safety. Using 30-50% phosphoric acid as a neutralizing agent to adjust the pH of the red mud prevents its strong alkalinity from adversely affecting the microorganisms in the mixed biocrust.

[0081] Example 8

[0082] Ozone micro-nano bubbles were injected into the sludge for oxidation treatment. The ozone dosage was 0.1 g / g, the air intake rate was 2.0 L / min, and the reaction time was 20 min. The red mud was neutralized with 30% phosphoric acid as a neutralizing agent to adjust its pH, and then washed and separated. 20 parts of the mixed bio-crust, 50 parts of sludge, and 10 parts of red mud were mixed and pretreated by drying, crushing, and sieving to obtain a solid waste-based bio-crust type compound organic fertilizer.

[0083] Example 9

[0084] Ozone micro-nano bubbles were injected into the sludge for oxidation treatment. The ozone dosage was 0.2 g / g, the air intake rate was 1.8 L / min, and the reaction time was 30 min. The red mud was neutralized with 40% phosphoric acid as a neutralizing agent, and then washed and separated. 15 parts of the mixed biocrust, 40 parts of sludge, and 5 parts of red mud were mixed and pretreated by drying, crushing, and sieving to obtain a solid waste-based biocrust type compound organic fertilizer.

[0085] The solid waste-based bio-crust type compound organic fertilizer is added at a dosage of 5-10% to the improved shield tunneling slag soil described in Example 4 to obtain ecological restoration soil (S3). This step includes adding 5-10% of the solid waste-based bio-crust type compound organic fertilizer to the improved shield tunneling slag soil to prepare ecological restoration soil. The ecological restoration soil is laid on the surface of mine wounds, green areas, etc., with a thickness of 50-60cm. Native plants adapted to the local environment, such as herbaceous plants, shrubs, and trees, are planted.

[0086] It is understandable that combining improved tunnel boring machine (TBM) slag with solid waste-based bio-crust compound organic fertilizer can not only effectively solve the defects of TBM slag in terms of soil structure, nutrient content, anionic surfactant pollution, and heavy metal pollution, but also promote plant growth and improve the ecological environment through the synergistic effect of bio-crust and organic fertilizer.

[0087] Example 10

[0088] Ecological restoration soil was prepared by adding 5% solid waste-based bio-skin-type compound organic fertilizer to the improved shield tunnel slag. This ecological restoration soil was then laid on the surface of mine excavations and green areas, with a thickness of 60cm. Native plants adapted to the local environment, including herbaceous plants, shrubs, and trees, were then planted.

[0089] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing ecological restoration soil by regenerating contaminated waste soil using microbial remediation, characterized in that... Includes the following steps: (1) After mixing dried straw powder with a bimetallic alkaline solution, the mixture is matured and then pyrolyzed at a temperature above 500°C under a protective atmosphere to obtain modified biochar material; the bimetallic alkaline solution is prepared by mixing FeCl3 and Mg(OH)2 in a molar ratio of 1:2 in NaOH solution, with pH = 8~10, Fe 3+ The solution concentration was 1 mol / L; the dried straw powder and bimetallic alkali solution were mixed at a solid-liquid ratio of 1:10 g / mL, heated to 60~80℃, and matured for 10 hours. (2) The modified biochar material is mixed with microbial inoculum, shaken for adsorption, and freeze-dried to obtain a carbon-based biocomposite material; The microbial culture solution used was a mixed culture solution containing Pseudomonas, Klebsiella, *Xanthomonas humanis*, and *Neorhizium*, with an OD of [missing information]. 600 If the value is >0.8, add 5 vt% of the bacterial solution to the culture medium and mix it with the modified biochar material at a solid-liquid ratio of 1:100 mg / mL. (3) The carbon-based biocomposite material is mixed with shield tunneling slag to obtain improved shield tunneling slag; (4) Mix the improved shield tunnel slag with organic fertilizer to obtain soil for ecological restoration; the composition of the organic fertilizer by weight is as follows: 30-50 parts of modified sludge, 5-10 parts of modified red mud, and 10-20 parts of mixed biological crust. The modified sludge is prepared in the following manner: Ozone micro-nano bubbles are injected into the sludge for oxidation treatment. The ozone dosage is 0.1~0.2 g / g of sludge, and the reaction time is 20~30 min. The sludge comes from an urban sewage treatment plant and contains organic matter, nitrogen, and phosphorus. The modified red mud is prepared in the following manner: The pH of the red mud was adjusted to 6.5-7.5 using 30-50 wt% phosphoric acid as a neutralizing agent, and then washed and separated to obtain modified red mud. The hybrid biological crust is prepared in the following manner: Mix 50-70 parts by weight of algae-lichen type biocrust, 1-5 parts by microbial inoculant, 10-20 parts by weight of HEPES buffer, and 5-10 parts by weight of gum arabic binder. Incubate for 3-5 days at 25-30°C and 60-80% humidity with 8-12 hours of light per day. Remove excess water to obtain a stable mixed biocrust. The microbial inoculant consists of rhizobium, Bacillus subtilis, and Pseudomonas aeruginosa. The microbial culture solution was prepared using the following method: The types and concentrations of anionic surfactants in the shield tunnel slag were obtained, and an inorganic salt culture solution was prepared using the anionic surfactants as the sole carbon source. Microbial cells were extracted from the precipitate of activated sludge samples produced by wastewater treatment plants, washed three times by resuspending in sterile phosphate buffer solution, and the precipitate solids were inoculated into the inorganic salt culture medium. The mixture was then cultured at 30°C and 180 rpm for 7 days to obtain the inoculum. The inoculum was added to the new inorganic salt culture medium at a 5% inoculum amount. The concentration of anionic surfactant in the culture medium was increased generation by generation to screen and enrich bacterial groups. The culture was carried out at 30°C and 180 rpm for 3 days. The culture was repeated 3 times to obtain the target bacterial culture that efficiently degrades anionic surfactants.

2. The method for preparing ecological restoration soil by regenerating contaminated waste soil using microorganisms as described in claim 1, characterized in that... The dried straw powder described in step 1 is soaked in deionized water, washed, and dried.

3. The method for preparing ecological restoration soil by regenerating contaminated waste soil using microorganisms as described in claim 1, characterized in that... In step 1, the pyrolysis process is carried out in a quartz tube furnace under N2 protective gas, with a heating rate of 10℃ / min and a pyrolysis time of 2 hours.

4. The method for preparing ecological restoration soil by regenerating contaminated waste soil using microorganisms as described in claim 1, characterized in that... The amount of anionic surfactant leached from the improved shield tunneling slag in step 3 is less than 0.3 mg / L.

5. The method for preparing ecological restoration soil by regenerating contaminated waste soil using microbial remediation as described in claim 1, characterized in that... In step 3, the carbon-based biocomposite material is activated at 30°C and 180 rpm for 48 hours before being mixed with the tunnel boring machine slag.

6. The method for preparing ecological restoration soil by regenerating contaminated waste soil using microbial remediation as described in claim 1, characterized in that... In step 3, the carbon-based biocomposite material is mixed with the tunnel boring machine slag at a mass ratio of 1:

50.

7. The method for preparing ecological restoration soil by regenerating contaminated waste soil using microbial remediation as described in claim 1, characterized in that... The amount of organic fertilizer added in step 4 is 5~10wt%.

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