Method for regenerating and preparing soil for ecological restoration by utilizing microbial restoration polluted residue soil

Abstract

The invention discloses a method for regenerating and preparing soil for ecological restoration by utilizing microbial restoration pollution muck, which comprises the following steps: stirring and mixing dry straw powder and bimetallic alkali liquor, drying, heating to 500 DEG C or above under a protective atmosphere, and pyrolyzing to obtain a modified biochar material; mixing the modified biochar material with a microbial liquid, oscillating and adsorbing, and freeze-drying to obtain the carbon-based biological composite material. The carbon-based biological composite material and shield muck are mixed to obtain improved shield muck; mixing the improved shield muck with an organic fertilizer to obtain soil for ecological restoration; toxic and harmful components in the shield muck are removed through biodegradation, the shield muck is subjected to structure improvement through the modified biochar, then the composite fertilizer with specific components is matched, resource utilization of the shield muck is achieved, and the shield muck-based ecological restoration soil is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste utilization, and specifically relates to a method for preparing soil for ecological restoration by regenerating polluted slag using microorganisms. Background Art

[0002] The rapid development of urban rail transit, especially the laying of subway lines, is inseparable from shield construction technology. Shield construction has the advantages of fast construction speed, high safety, and little impact on ground traffic. It is one of the main technical means for urban underground engineering construction. However, with the continuous improvement of shield technology, it is inevitable to add additives mainly based on surfactants such as foaming agents and dispersants to improve the efficiency of excavation construction. A large amount of biologically toxic engineering waste shield slag is generated every year, which brings new challenges to the urban ecological environment and land resources. Faced with increasingly serious environmental pollution, instability risks and land occupation problems, open-air stacking and landfill-based disposal methods will no longer be applicable. Therefore, the safe treatment and disposal (pollutant reduction, structural improvement) and resource utilization (ecological restoration application) of shield slag are engineering problems that need to be solved urgently at this stage.

[0003] At the same time, the study found that shield waste has many defects and limitations when used for plant growth and planting, such as insufficient nutrient content, low soil biological activity, and unstable physical and chemical properties. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing soil for ecological restoration by regenerating contaminated slag using microorganisms, removing toxic and harmful components in shield slag through biodegradation, and then combining with a compound fertilizer with specific ingredients to achieve resource utilization of shield slag and obtain soil for ecological restoration of shield slag base.

[0005] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0006] The method for preparing soil for ecological restoration by regenerating contaminated slag using microorganisms comprises the following steps:

[0007] (1) mixing dry straw powder with bimetallic alkali solution, aging the mixture, and heating the mixture to above 500° C. under a protective atmosphere to obtain a modified biochar material;

[0008] (2) The modified biochar material is mixed with a microbial culture solution, subjected to oscillation adsorption, and freeze-dried to obtain a carbon-based biocomposite material;

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

[0010] (4) The improved shield waste soil is mixed with organic fertilizer to obtain soil for ecological restoration.

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

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

[0013] According to the above scheme, in step 1, the dry straw powder and the bimetallic alkali solution are mixed at a solid-liquid ratio of 1:10 g / mL, the temperature is raised to 60-80° C., and the aging time is 10 h.

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

[0015] According to the above scheme, the microbial culture liquid in step 2 is prepared by the following method:

[0016] Obtaining the type and concentration of anionic surfactants in the shield slag, including but not limited to one or more of the common main components of shield slag foaming agents, sodium dodecyl sulfate (SDS), fatty alcohol polyoxyethylene ether sulfate (AES), and α-olefin sulfonate (AOS); preparing an inorganic salt culture solution with one or more anionic surfactants as the sole carbon source;

[0017] Extract the activated sludge sample produced by the sewage treatment plant to obtain the microbial cells by precipitation and separation, resuspend and wash three times with a sterile phosphate buffered saline solution, inoculate the precipitated solid part into the culture solution, and culture on a shaking table at 180 rpm at 30° C. for 7 days to obtain an inoculum solution;

[0018] The inoculation solution was added to the new culture solution at a 5% inoculation rate, the concentration of anionic surfactant in the culture solution was increased generation by generation to screen the enriched bacterial population, the culture was cultured on a shaking table at 180 rpm at 30° C. for 3 days, and the culture was continued for 3 times to obtain the target bacterial solution with high efficiency in degrading anionic surfactants.

[0019] According to the above scheme, the microbial solution in step 2 is a mixed solution containing Pseudomonas, Klebsiella, Human Yellow Bacillus, and New Rhizobium, with an OD 600 When the value was >0.8, 5vt% of bacterial solution was added to the culture medium and mixed with the modified biochar material at a solid-liquid ratio of 1:100mg / mL.

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

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

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

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

[0024] 30-50 parts of modified sewage sludge, 5-10 parts of modified red mud, and 10-20 parts of 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 0.1-0.2g / g sludge, and the reaction time is 20-30min; the sludge comes from a municipal 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 red mud is adjusted to a pH of 6.5 to 7.5 using 30 to 50 wt% phosphoric acid as a neutralizer, 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] 50-70 parts of algae-lichen type biological crust, 1-5 parts of microbial agent, 10-20 parts of HEPES buffer and 5-10 parts of gum arabic adhesive are mixed by weight, cultured for 3-5 days under the conditions of temperature of 25-30°C and humidity of 60-80% under illumination for 8-12 hours per day, and then excess water is removed to obtain a stable mixed biological crust; the microbial agent consists of rhizobia, bacillus subtilis and pseudomonas forsythiae.

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

[0032] Carbon-based biomaterials can effectively reduce shield slag pollutants while improving soil properties. Among them, the screening of target microorganisms can be widely used in the degradation of surfactant pollutants, which has the advantages of low carbon, low cost and environmental sustainability; biochar has the functions of adsorbing pollutants and enhancing the mechanical properties of soil, and is widely used in the fields of environment, geotechnical and agriculture. The degradation performance of the target microorganisms can make up for the defect that biochar cannot completely eliminate pollutants, and the addition of biochar can provide a favorable survival carrier for microorganisms and improve the soil aggregation structure.

[0033] It is necessary to combine the ecological restoration soil made by improving shield slag with carbon-based biomaterials with organic fertilizers for co-planting to optimize the community structure and diversity of microorganisms. Solid waste-based biocrust composite organic fertilizer is an organic fertilizer technical formula with sludge and red mud as solid waste-based components and mixed biocrust as auxiliary materials. Sludge is rich in organic matter, nitrogen, phosphorus, potassium and other nutrients, and red mud contains 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 water retention and aeration of the soil. The mixed biocrust is rich in algae, lichens, mosses and microorganisms, including nitrogen-fixing bacteria, potassium-dissolving bacteria, phosphate-dissolving bacteria, etc., which are beneficial to nutrient circulation, improve the nutrient effectiveness of the soil, and promote plant colonization and growth.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The carbon-based biomaterials as a modifier for ecological restoration of shield slag soil in the present invention include loading efficient degradation bacteria on modified biochar, wherein the efficient degradation bacteria can be widely used in the degradation of surfactant-type pollutants, and the modified biochar not only serves as a favorable survival carrier of biological loads, but also has the functions of adsorbing pollutants, improving soil agglomeration structure, and enhancing soil mechanical properties. The carbon-based biomaterials can improve the synergistic structure of shield slag pollution reduction, reduce the biological effectiveness and mobility of pollutants in the soil, and reduce their harm to plants and soil ecosystems.

[0036] In the present invention, soil for ecological restoration of shield slag foundation and solid waste-based biological crust type composite organic fertilizer are combined to prepare soil for ecological restoration. The sludge in the solid waste-based biological crust type composite organic fertilizer is rich in organic matter, nitrogen, phosphorus, potassium and other nutrients, and red mud contains minerals such as iron, aluminum, silicon, etc. The synergistic effect of sludge and red mud can supplement the trace elements in the soil and improve the water retention and air permeability of the soil; the algae, lichens and microorganisms rich in the mixed biological crust can optimize the community structure and diversity of microorganisms. These microorganisms include nitrogen-fixing bacteria, potassium-dissolving bacteria, phosphate-dissolving bacteria, etc., which are beneficial to nutrient circulation, improve the nutrient effectiveness of the soil, and facilitate it to continuously and slowly provide nutrients to plants, thereby promoting the colonization and growth of plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 : A method for improving shield slag using carbon-based biocomposite materials.

[0038] Figure 2 : A method for obtaining soil for ecological restoration by utilizing improved shield slag and compound organic fertilizer. DETAILED DESCRIPTION

[0039] The following examples 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 liquid:

[0041] Prepare inorganic salt culture medium with AS as the sole carbon source, including 3.67g / L inorganic salt basal medium (Chinook, catalog number CN230590), 0.5g / L EDTA-disodium (Phygene, catalog number PH9041), AS standard solution with a concentration gradient of 100, 200, 500, 600, 800, 1000, and 1200 mg / L; extract the activated sludge sample and centrifuge at 3000 rpm to obtain precipitated microbial cells, resuspend and wash 3 times with sterile phosphate buffered saline (PBS) (Biosharp, catalog number BL601A), inoculate the precipitated solid part in a container containing AS culture medium, and culture on a shaking table at 180 rpm, 30°C for 7 days to obtain inoculum; add the inoculum into new AS culture medium at a 5% inoculum amount, and culture on a shaking table at 180 rpm, 30°C for 3 days; increase the concentration of AS culture medium generation by generation to screen and enrich, and culture continuously for 5 times to obtain a microbial culture with high efficiency in AS degradation performance.

[0042] The specific embodiment provides a hybrid biocrust:

[0043] Mature algae-lichen type biocrusts were collected, dried naturally or at a temperature below 40°C, and crushed to a particle size of less than 0.15 mm; purchased Rhizobium cellulosilyticum (CGMCC 1.15995), Bacillus subtilis (CGMCC 1.3358), and Pseudomonas guguanensis (CGMCC 1.15627) were expanded and cultured in a ratio of 1-2:5-6:2-3, and prepared into microbial agents by centrifugation or filtration concentration, ensuring that the number of viable bacteria was 3×10 9 CFU / g; prepare 20mM HEPES buffer and adjust the pH to about 6.5-7.5 with 0.5-1M NaOH, prepare 5-10% gum arabic adhesive solution, filter and sterilize it as an auxiliary material; fully mix the algae-lichen type biological crust in a proportion of 50-70, microbial agent 1-5, HEPES buffer 10-20, and gum arabic adhesive 5-10 for 10-20 minutes, culture at a temperature of 25-30°C and a humidity of 60-80% for 3-5 days with light exposure of 8-12 hours per day, and then remove excess water to form a stable mixed biological crust.

[0044] A specific embodiment provides a solid waste-based biocrust type composite organic fertilizer, which uses modified sludge and modified red mud as solid waste-based components and a mixed biocrust as an auxiliary material in an organic fertilizer technical formula; the composite organic fertilizer is calculated by dry weight, with 30 to 50 parts of modified sludge, 5 to 10 parts of modified red mud, and 10 to 20 parts of mixed biocrust.

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

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

[0047] The specific implementation method provides a method for preparing soil for ecological restoration by regenerating contaminated slag using microorganisms:

[0048] (1) After screening the straw powder, soak and wash the straw powder with deionized water to remove excess soluble salt impurities, dry it for 24 hours, and then seal and dry it for storage; stir the dried straw powder and bimetallic alkali solution at a solid-liquid ratio of 1:10 (g / mL) at room temperature for 30 minutes to mix evenly, wherein the bimetallic alkali solution is prepared by FeCl3·6H2O and Mg(OH)2 at a molar ratio of 1:2, and place them together in a magnetic stirrer at 60-80°C for 10 hours, and adjust the pH to 8-10 with NaOH solution; recover the solid phase component by high-speed centrifugation at 8000rpm for 10 minutes, rinse it with deionized water for 3 times, and dry it in an oven at 105°C for 24 hours; heat the dried material in a quartz tube furnace at a rate of 10°C / min to 500°C for constant temperature pyrolysis for 2 hours, and pass N2 protective gas with a flow rate of 100mL / min throughout the process to obtain a modified biochar material.

[0049] (2) The modified biochar material was mixed with the above-mentioned microbial culture liquid, and adsorbed on a shaker at 180 rpm and 30° C. for 12 h. The mixed suspension was filtered and rinsed with PBS three times, and freeze-dried to obtain a carbon-based biocomposite material, which was stored at 4° C. for future use.

[0050] (3) After the carbon-based biocomposite material is activated by a culture medium at 30°C and 180 rpm for 48 hours, it is evenly sprayed on the shield slag (the mass ratio of the two is 1:50). During the spraying process, the material flow and uniformity are controlled to avoid excessive or low local concentration. After spraying, a secondary stirring is performed to ensure that the material is fully contacted and mixed with the shield slag to prepare the improved shield slag; the concentration of anionic surfactant leaching in the improved shield slag foundation ecological restoration soil meets the requirements of the groundwater and surface water environmental quality standards of less than 0.3 mg / L.

[0051] (4) Add 5-10 wt% of solid waste-based biocrust-type composite organic fertilizer to the improved shield slag to produce soil for ecological restoration, which is then laid on the surface of mine wounds, green land, etc. with a thickness of 50-60 cm; native plants, herbaceous plants, shrubs and trees that are adapted to the local environment can be planted.

[0052] The present application provides a method for improving shield slag with a carbon-based biocomposite material. Figure 1 This method loads the highly efficient degradation bacteria on the modified biochar by physical adsorption and fixation. The synthesized carbon-based biocomposite material can make up for the defect that biochar cannot completely eliminate pollutants through the degradation performance of the target microorganisms, and has the advantages of low carbon, low cost and environmental sustainability; and the addition of biochar can provide a favorable survival carrier for microorganisms, which can enhance the mechanical properties of the soil while adsorbing pollutants, increase the porosity of the soil, improve the air permeability and water permeability of the soil, and improve the soil aggregation structure.

[0053] Extract microbial concentrate from activated sludge, increase the concentration of AS culture solution generation by generation to screen and enrich, and obtain target bacterial solution (S1) with high efficiency in AS degradation. This step includes obtaining shield agents of different formulations used in different construction projects and the dosage of anionic surfactants in the formulations, diluting the shield agents to the required target pollutant concentration of 100-1200 mg / L, and preparing inorganic salt culture solution with AS as the sole carbon source; extracting activated sludge samples produced by sewage treatment plants and centrifuging at 3000 rpm to obtain precipitated microbial cells, resuspending and washing 3 times with sterile phosphate buffered saline solution, inoculating the precipitated solid part in a container containing AS culture solution, and culturing at 180 rpm on a shaker at 30°C for 7 days to obtain an inoculum; adding the inoculum to a new AS culture solution at a 5% inoculum amount, and culturing at 180 rpm on a shaker at 30°C for 3 days; increasing the concentration of AS culture solution generation by generation to screen and enrich the bacterial community, and continuously subculturing for 3 times to obtain a target bacterial solution with high efficiency in AS degradation of anionic surfactants.

[0054] It is understood that the anionic surfactant in the shielding agent has the same 2+ Mg 2+The characteristics of metal ions such as AS forming turbid complexes affect the subsequent OD600 value observation of the growth of the culture medium flora. When using 3.67g / L inorganic salt basal medium (Chinook, item number CN230590), 0.5g / L EDTA-disodium (Phygene, item number PH9041) is used to ensure that the OD value of the culture medium after adding different concentrations of AS is not affected by the target pollutant itself. Anionic surfactants have the property of being easily decomposed at high temperature. After the inorganic salt basal medium and EDTA-disodium are sterilized at 121℃ and the anionic surfactant solution is sterilized by filtering through a 0.22μm PES filter membrane, 100, 200, 500, 600, 800, 1000, and 1200mg / L AS culture fluids are obtained. Washing the inoculum extracted from the activated sludge with sterile phosphate buffered saline (PBS) (Biosharp, catalog number BL601A) can stabilize the pH of the living environment of the microorganisms within a certain range, thereby prolonging the growth and reproduction activity of the microorganisms.

[0055] The preparation is described below according to different embodiments:

[0056] Example 1

[0057] The dosage of anionic surfactant in the shield agent formula used in a certain construction project is 1.4% sodium dodecyl sulfate (SDS), 3.2% α-olefin sulfonate (AOS), 1.6% sodium dodecylbenzene sulfonate (SDBS), and 2.3% sodium fatty alcohol polyoxyethylene ether sulfate (AES). After dilution, it is mixed with 3.67 g / L inorganic salt culture medium and 0.5 g / L EDTA-disodium to prepare culture solutions with concentrations of 100, 200, 500, 600, 800, 1000, and 1200 mg / L respectively, with AS as the sole carbon source. The activated sludge sample was resuspended and washed three times with sterile phosphate buffered saline solution and centrifuged at 3000rpm to obtain precipitated microbial cells. The precipitated solid part was inoculated in AS culture medium and cultured at 180rpm for 7 days at 30℃ to obtain inoculum. The inoculum was added to the new culture medium with increased AS concentration at a 5% inoculum amount, and cultured at 180rpm for 3 days at 30℃. The target bacterial liquid with high efficiency in degrading anionic surfactant AS was screened and enriched for three times. After testing, the mixed bacterial liquid mainly contained Pseudomonas, Klebsiella, Luteibacter anthropi, and Neorhizobium, and the OD 600 Value>0.8.

[0058] Example 2

[0059] The dosage of anionic surfactant in the shield agent formula used in a construction project is 2.7% sodium dodecyl sulfate (SDS), 4.0% α-olefin sulfonate (AOS), and 6.4% sodium polyoxyethylene sulfate (AES). After dilution, it is prepared with 3.67g / L inorganic salt culture medium and 0.5g / L EDTA-disodium to prepare culture solutions with concentrations of 200, 500, 800, 1000, and 1200mg / L, respectively, with AS as the sole carbon source. The activated sludge sample is resuspended and washed three times with sterile phosphate buffered saline solution and centrifuged at 3000rpm to obtain precipitated microbial cells. The precipitated solid part is inoculated in the AS culture solution, and cultured at 180rpm at 30℃ for 7d to obtain the inoculum solution; the inoculum solution is added to the new culture solution with increased AS concentration at a 5% inoculum amount, and cultured at 180rpm at 30℃ for 3d, and subcultured three times continuously to screen and enrich the target bacterial solution that efficiently degrades anionic surfactant AS.

[0060] Using straw powder, FeCl3·6H2O, Mg(OH)2, and NaOH as raw materials, magnesium-iron bimetallic co-alkaline maturation and co-carbonization to obtain modified biochar (S2). This step includes mixing dry straw powder with FeCl3·6H2O solution and Mg(OH)2 powder and adjusting the pH to alkaline with NaOH solution, maturing at 60-80°C for 10 hours, and drying to obtain magnesium-iron bimetallic modified straw powder material. The magnesium-iron bimetallic modified straw powder material is carbonized and pyrolyzed at 500°C in a quartz tube furnace under N2 protective gas for 2 hours to obtain magnesium-iron bimetallic modified biochar material.

[0061] It is understandable that the types of straw powder can be corn straw powder, peanut straw powder, rice straw powder, etc. Different types of straw powder affect the properties of biochar generated by subsequent carbonization. During the alkali maturation 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, and fully contact with biomass before carbonization, which can more effectively promote the decomposition and activation of biomass, form more microporous and mesoporous structures, and increase the specific surface area of ​​modified biochar.

[0062] Example 3

[0063] After selecting and sieving the straw powder, soak and wash the straw powder with deionized water to remove excess soluble salt impurities, dry it for 24 hours, and then seal and dry it for storage; stir the dried straw powder and bimetallic alkali solution at a solid-liquid ratio of 1:10 (g / mL) for 30 minutes at room temperature to mix evenly, wherein the bimetallic alkali solution is prepared by FeCl3·6H2O solution and Mg(OH)2 powder in a molar ratio of 1:2, and place them together in a magnetic stirrer at 70°C for 10 hours, and adjust the pH to 9 with NaOH solution; recover the solid phase component by high-speed centrifugation at 8000rpm for 10 minutes, rinse it with deionized water for 3 times, and dry it in an oven at 105°C for 24 hours; heat the dried material in a quartz tube furnace at a rate of 10°C / min to 500°C for constant temperature pyrolysis for 2 hours, and pass N2 protective gas with a flow rate of 100mL / min throughout the process to obtain modified biochar material.

[0064] The highly efficient degradation bacteria are loaded on the modified biochar by physical adsorption and fixation to obtain a carbon-based biocomposite material (S3). This step includes mixing and adsorbing the modified biochar obtained by co-carbonizing the straw powder after the bimetallic co-alkali maturation with the target bacterial liquid of the highly efficient anionic surfactant AS at a loading ratio of 1:200 (g / mL) to form a carbon-based biocomposite material.

[0065] It is understandable that the porous structure, rich surface functional groups and microbial activity of the synthesized carbon-based biocomposite materials enable it to efficiently adsorb and degrade pollutants in the soil, while also improving the soil aggregate structure, providing nutrient elements, promoting soil microbial activity, regulating soil pH, and other functions to improve the structure of shield slag.

[0066] Example 4

[0067] The cultured bacterial solution was centrifuged at 4500 rpm for 5 min, the supernatant was removed to retain the solid bacterial cells, and the bacterial cells were washed twice with 0.9% saline. After each centrifugation, the bacterial cells were resuspended. The washed bacterial cells were resuspended with 0.9% saline to make a uniform bacterial suspension, ensuring that the number of viable bacteria was 2.0×10 9 CFU / mL(OD 600 =1). The pre-cleaned modified biochar material was mixed with 0.9% physiological saline and sterilized with high-temperature and high-pressure steam at 121°C for 20 minutes; after filtration, 0.5g of the material with a particle size of 0.1-0.3mm was sieved and transferred into the above 100mL bacterial suspension, and oscillated at 180rpm at 30°C for 12 hours. Before the bacterial growth curve reached its peak, the bacterial suspension in the conical flask was filtered with Whatman No.5 ash-free slow qualitative filter paper 2.5μm (1-3μm), and rinsed 3 times with 0.1M phosphate buffered saline PBS (pH7.4) to obtain the carbon-based biocomposite adherent, which was freeze-dried and stored at 4°C for later use.

[0068] The carbon-based biocomposite material is mixed with shield slag in a mass ratio of 1:50 to obtain improved shield slag (S4). This step includes naturally drying the shield slag or mechanically drying it, removing excess moisture below 60°C to avoid high temperature causing changes in soil properties; using a vibrating screen to screen the shield slag to remove large particles of impurities and construction waste to obtain soil particles with a particle size of less than 2 mm. The synthesized carbon-based biocomposite material is crushed and screened into particles with a particle size of less than 0.1 mm, and evenly mixed with the shield slag to form improved shield slag with a moisture content of 20%.

[0069] It is understandable that the concentration of anionic surfactant leaching in the improved shield slag meets the requirement of groundwater and surface water environmental quality standards of less than 0.3 mg / L. Through the coordinated structural improvement of pollution reduction treatment, it has multiple functions such as reducing pollutants, improving soil structure, providing nutrients, promoting microbial activity, and regulating pH. Its application not only solves the environmental pollution problem of shield slag, but also provides an efficient and environmentally friendly solution for ecological restoration, with significant economic, social and ecological benefits.

[0070] The present application provides a method for obtaining soil for ecological restoration by combining improved shield slag with solid waste-based biocrust composite organic fertilizer. Figure 2 As shown. This method uses sewage sludge and red mud as matrix components and synthesizes solid waste-based biocrust-type composite organic fertilizer with collected algae-lichen type biocrust, which is rich in organic matter, nutrient elements and microbial activity. After the improved shield slag is mixed with solid waste-based biocrust-type composite organic fertilizer, it can not only improve the physical structure of the soil, but also effectively increase the biological activity, and can be efficiently applied to abandoned land, mining areas, highway slopes and other working conditions. On the basis of improving the soil, this method plants suitable plants, which can make full use of nutrients and microbial communities in the soil and promote rapid plant growth and vegetation recovery.

[0071] Example 5

[0072] The shield slag of a construction project was naturally aired or mechanically dried at a temperature below 60°C, and then sieved with a 2 mm vibrating screen to obtain soil particles. The carbon-based biocomposite material synthesized in Example 4 was crushed and sieved into particles with a particle size of less than 0.1 mm, and mixed with the shield slag at a mass ratio of 1:50, and water was added to mix to form 20% improved shield slag.

[0073] The method comprises the following steps: 50-70 parts of algae-lichen type biological crust, 1-5 parts of microbial agent, 10-20 parts of HEPES buffer and 5-10 parts of gum arabic are mixed to obtain a mixed biological crust. This step comprises collecting mature algae-lichen type biological crust and drying, crushing and screening to obtain a biological crust dry material with certain fertility; purchasing strains from a preservation center and expanding the culture to obtain a mixed microbial agent; preparing HEPES buffer (Biofroxx, item number 1112GR500) and gum arabic (Kermel, CAS number 9000-01-5) adhesive to a certain concentration, adjusting the pH to a range of 6.5-7.5, and filtering and sterilizing to obtain an auxiliary material.

[0074] It is understandable that mature algae-lichen type biological crusts are rich in nutrients and organic matter required by plants, which can provide a good habitat for soil microorganisms and promote the growth and reproduction of microorganisms. By adding mixed microbial agents, it is beneficial to the presence of specific microbial flora required for plant growth, and the ecological diversity and stability of the soil are improved. HEPES buffer and gum arabic adhesive are used as auxiliary materials. On the one hand, HEPES buffer avoids the growth and reproduction of the flora and the secretion of acidic substances to change the physical and chemical properties of the soil in terms of maintaining the pH stability of the soil environment. On the other hand, gum arabic adhesive is a natural renewable material with good adhesion, film-forming properties, biocompatibility and versatility, and can effectively bond the dried material of algae-lichen type biological crusts with microbial agents to form a stable mixed biological crust (S1).

[0075] Example 6

[0076] Mature algae-lichen type biocrusts were collected, dried naturally or at a temperature below 40°C, and crushed to a particle size of less than 0.15 mm. The purchased Rhizobium cellulosilyticum (CGMCC 1.15995), Bacillus subtilis (CGMCC 1.3358), and Pseudomonas guguanensis (CGMCC 1.15627) were expanded and cultured in a ratio of 2:6:2, and concentrated by centrifugation or filtration to prepare a microbial agent, ensuring that the number of viable bacteria was 3×10 9CFU / g; prepare 20mM HEPES buffer and adjust the pH to about 6.5-7.5 with 0.5-1M NaOH, prepare 5% gum arabic adhesive solution, filter and sterilize it as an auxiliary material; fully mix the algae-lichen type biological crust 70, microbial agent 5, HEPES buffer 10, and gum arabic adhesive 5 in a range of proportions for 10-20min, cultivate at a temperature of 25-30℃ and a humidity of 60-80% under light for 8-12h per day for 3-5 days, and then remove excess water to form a stable mixed biological crust.

[0077] Example 7

[0078] Mature algae-lichen type biocrusts were collected, dried naturally or at a temperature below 40°C, and crushed to a particle size of less than 0.15 mm. The purchased Rhizobium cellulosilyticum (CGMCC 1.15995), Bacillus subtilis (CGMCC 1.3358), and Pseudomonas guguanensis (CGMCC 1.15627) were expanded and cultured in a ratio of 2:5:3, and concentrated by centrifugation or filtration to prepare a microbial agent, ensuring that the number of viable bacteria was 3×10 9 CFU / g; prepare 20mM HEPES buffer and adjust the pH to about 6.5-7.5 with 0.5-1M NaOH, prepare 10% gum arabic adhesive solution, filter and sterilize it as an auxiliary material; fully mix the algae-lichen type biological crust 60, microbial agent 3, HEPES buffer 20, and gum arabic adhesive 5 in a range of proportions for 10-20min, cultivate at a temperature of 25-30℃ and a humidity of 60-80% under light for 8-12h per day for 3-5 days, and then remove excess water to form a stable mixed biological crust.

[0079] 10 to 20 of the mixed biological crust, 30 to 50 of the sludge, and 5 to 10 of the red mud are mixed to obtain a solid waste-based biological crust type composite organic fertilizer. This step includes injecting ozone micro-nano bubbles into the sludge for oxidation treatment, with an ozone dosage of 0.1 to 0.2 g / g, an air intake of 1.8 to 2.0 L / min, and a reaction time of 20 to 30 min. The red mud is adjusted to a pH value using 30 to 50% concentration of phosphoric acid as a neutralizer, and is washed and separated. After pre-treatment of the sludge, red mud, and mixed biological crust by drying, crushing, screening, etc., a solid waste-based biological crust type composite organic fertilizer (S2) is obtained.

[0080] It is understandable that the injection of ozone micro-nano bubbles into the sludge for oxidation treatment is intended to utilize the strong oxidizing property of ozone and the efficient mass transfer characteristics of micro-nano bubbles to oxidize and decompose and remove organic matter, heavy metals, pathogens, etc. in the sludge, which can not only effectively reduce the water content of the sludge, but also reduce harmful substances in the sludge and improve the stability and safety of the sludge. Phosphoric acid with a concentration of 30-50% is used as a neutralizer to adjust the pH of the red mud to avoid the strong alkalinity of the red mud from adversely affecting the microorganisms in the mixed biological crust.

[0081] Example 8

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

[0083] Example 9

[0084] Ozone micro-nano bubbles were injected into the sludge for oxidation treatment, with an ozone dosage of 0.2 g / g, an air intake of 1.8 L / min, and a reaction time of 30 min. The red mud was neutralized with 40% phosphoric acid to adjust its pH, and then washed and separated. 15 parts of the mixed biological crust, 40 parts of sludge, and 5 parts of red mud were mixed and pre-treated by drying, crushing, screening, etc. to obtain a solid waste-based biological crust type composite organic fertilizer.

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

[0086] It can be understood that the combination of improved shield slag and solid waste-based bio-crust-type composite organic fertilizer can not only effectively solve the defects of shield slag in soil structure, nutrient content, anionic surfactant pollution, heavy metal pollution, etc., but also promote plant growth and improve the ecological environment through the synergistic effect of bio-crust and organic fertilizer.

[0087] Example 10

[0088] Add 5% of solid waste-based biocrust compound organic fertilizer to the improved shield slag to make soil for ecological restoration. Spread the soil for ecological restoration on the surface of mine wounds, green land, etc., with a thickness of 60cm. Plant native plants that adapt to the local environment, such as herbs, shrubs and trees.

[0089] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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 only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms, characterized in that The following steps are involved: (1) mixing dry straw powder with bimetallic alkali solution, aging the mixture, and heating the mixture to above 500° C. under a protective atmosphere to obtain a modified biochar material; (2) The modified biochar material is mixed with a microbial culture solution, subjected to oscillation adsorption, and freeze-dried to obtain a carbon-based biocomposite material; (3) The carbon-based biocomposite material is mixed with shield slag to obtain improved shield slag; (4) The improved shield waste soil is mixed with organic fertilizer to obtain soil for ecological restoration.

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

3. The method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms as claimed in claim 1, characterized in that Step 1: The bimetallic alkali solution is prepared by mixing FeCl3 and Mg(OH)2 in a NaOH solution at a molar ratio of 1:2, with a pH of 8 to 10. 3+ The solution concentration is 1 mol / L.

4. The method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms as claimed in claim 1, characterized in that In step 1, the dried straw powder and the bimetallic alkali solution are mixed at a solid-liquid ratio of 1:10 g / mL, the temperature is raised to 60-80° C., and the aging time is 10 h.

5. The method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms as claimed in claim 1, characterized in that The pyrolysis process in step 1 is carried out in a quartz tube furnace with N2 protective gas, a heating rate of 10°C / min, and pyrolysis for 2h.

6. The method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms as claimed in claim 1, characterized in that In step 2, the microbial solution used was a mixed solution containing Pseudomonas, Klebsiella, Human Yellow Bacterium, and Neorhizobium, with an OD of 600 When the value was >0.8, 5vt% of bacterial solution was added to the culture medium and mixed with the modified biochar material at a solid-liquid ratio of 1:100mg / mL.

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

8. The method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms as claimed in claim 1, characterized in that In step 3, the carbon-based biocomposite material is activated in a culture medium at 30° C. and 180 rpm for 48 hours before being mixed with shield slag.

9. The method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms as claimed in claim 1, characterized in that In step 3, the carbon-based biocomposite material and shield slag are mixed in a mass ratio of 1:

50.

10. The method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms as claimed in claim 1, characterized in that The composition of the organic fertilizer in step 4 is as follows by weight: 30-50 parts of modified sludge, 5-10 parts of modified red mud, and 10-20 parts of mixed biological crust.

11. The method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms as claimed in claim 10, characterized in that 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 0.1-0.2g / g sludge, and the reaction time is 20-30min; the sludge comes from a municipal sewage treatment plant and contains organic matter, nitrogen and phosphorus.

12. The method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms as claimed in claim 10, characterized in that The modified red mud is prepared in the following manner: The red mud is treated with 30-50 wt% phosphoric acid as a neutralizer to adjust the pH value to 6.5-7.5, and then washed and separated to obtain modified red mud.

13. The method for preparing soil for ecological restoration by regenerating contaminated soil using microorganisms as claimed in claim 10, characterized in that The hybrid biological crust is prepared in the following manner: 50-70 parts of algae-lichen type biological crust, 1-5 parts of microbial agent, 10-20 parts of HEPES buffer and 5-10 parts of gum arabic adhesive are mixed by weight, cultured for 3-5 days under the conditions of temperature of 25-30°C and humidity of 60-80% under illumination for 8-12 hours per day, and then excess water is removed to obtain a stable mixed biological crust; the microbial agent consists of rhizobia, bacillus subtilis and pseudomonas forsythiae.

14. The method for preparing soil for ecological restoration by regenerating polluted soil using microorganisms as claimed in claim 1, characterized in that The amount of organic fertilizer added in step 4 is 5-10wt%.

15. The method for preparing soil for ecological restoration by regenerating polluted slag using microorganisms as claimed in claim 1, characterized in that The microbial culture liquid in step 2 is prepared in the following manner: Obtaining the type and concentration of anionic surfactant in the shield slag, and preparing an inorganic salt culture solution with the anionic surfactant as the sole carbon source; Extract the activated sludge sample produced by the sewage treatment plant to obtain the microbial cells by precipitation and separation, resuspend and wash three times with a sterile phosphate buffered saline solution, inoculate the precipitated solid part into the inorganic salt culture solution, and culture on a shaking table at 180 rpm at 30° C. for 7 days to obtain an inoculum solution; The inoculation solution is added to the new inorganic salt culture solution at a 5% inoculation amount, the concentration of anionic surfactant in the culture solution is increased generation by generation to screen the enriched bacterial population, the culture is carried out on a shaking table at 180 rpm at 30° C. for 3 days, and the culture is continuously subcultured for 3 times to obtain the target bacterial solution with high efficiency in degrading anionic surfactants.

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