Method and device for full-scale bioremediation of soil bioactivity by means of red mud

Abstract

The application relates to a method and device for full-amount biological soil bioactivity reclamation of red mud by a biological method, wherein the method comprises the following steps: S10, mixing cane pith powder and red mud at a certain ratio; S20, feeding livestock and poultry manure and first compound formula strains into a biological reactor, continuously feeding sterile air and keeping a certain temperature and pressure, forming internal circulation of fermentation substrates under the action of air flow and a flow guide cylinder, and becoming acidic substances under the action of microbial bacteria; S30, carrying out neutralization reaction of the acidic hydrolyzate and the red mud in a neutralization waste heat recovery reaction tank, outputting in the form of mud slurry, and carrying out pressure filtration to generate filter mud; S40, adding soil conditioner or bio-organic fertilizer and second compound formula strains to the filter mud, and improving the organic matter content and soil bioactivity; and S50, completing soilization under the combined action of multiple microorganisms. The technical scheme of the application solves the problems of waste of land resources and environmental pollution caused by red mud stacking in the prior art.

Description

Technical Field

[0001] This application relates to the technical field of red mud restoration, and more specifically, to a method and apparatus for the full-scale biological reclamation of red mud using a biological method. Background Technology

[0002] Red mud, also known as red clay, is an industrial solid waste discharged after alumina extraction from bauxite. It generally contains a high amount of iron oxide and resembles reddish soil in appearance, hence its name. However, some varieties contain less iron oxide and appear brown or even grayish-white. Red mud is an insoluble residue and can be classified into sintering red mud, Bayer process red mud, and combined process red mud. Its main components are SiO2, Al2O3, CaO, and Fe2O3. The storage of red mud on land not only wastes land resources but also makes it susceptible to leaching by rainwater and erosion by wind, thus polluting the surrounding atmosphere, water, and soil systems, posing a significant negative impact on the ecological health of the red mud storage site and its surrounding areas.

[0003] The application of red mud has been extensively studied both domestically and internationally. It mainly includes the preparation of building materials such as cement and as roadbed materials, the recovery of valuable metals, the preparation of special functional materials, and the treatment of water and air pollutants. However, due to many problems in the utilization of red mud, such as low resource utilization rate, unclear economic benefits, high energy consumption of utilization processes, and secondary pollution, it is still in the exploratory stage in many fields and has not yet been truly industrialized. Summary of the Invention

[0004] This application provides a method and apparatus for the full-scale biological reclamation of red mud using biological methods, in order to solve the problems of waste of land resources and environmental pollution caused by red mud stockpiling in the prior art.

[0005] According to the method for full-scale biological reclamation of red mud using biological methods provided in this application, the method includes the following steps: S10 mixing sugarcane pith powder and red mud in a certain proportion; S20 adding livestock and poultry manure and a first compound formula microbial inoculum into a bioreactor, continuously introducing sterile air while maintaining a certain temperature and pressure, the fermentation substrate forms an internal circulation under the action of airflow and a guide tube, and becomes an acidic substance under the action of microorganisms; simultaneously, the exhaust gas discharged from the bioreactor passes through a primary air compressor, an air filter, a secondary air compressor, and an ejector, mixes with fresh air to become a high-speed, high-pressure jet, and is introduced into the aeration fermentation tank. For fermentation of organic water-soluble fertilizer; S30 neutralizes acidic hydrolysate and red mud in a neutralization waste heat recovery reactor, producing a slurry, which is then filtered to generate filter mud; S40 adds soil conditioner or bio-organic fertilizer and a second compound formula of microorganisms to the filter mud to increase its organic matter content and soil biological activity; S50, under the combined action of multiple microorganisms, the regenerated soil meets all indicators, and can then be combined with fertigation technology (the organic water-soluble fertilizer fermented in the aerated fermentation tank is applied to the soil around the plant roots through drip irrigation) to plant specific plants to further improve the soil biological activity and complete the soilization.

[0006] Furthermore, the sugarcane pith powder consists of particles of approximately 2 mm, and the mass ratio of the sugarcane pith powder to the red mud is (0.3–0.8):1. Mixing the sugarcane pith powder with the strongly alkaline red mud can dissolve the lignin in the sugarcane pith into smaller molecules, promoting the separation of lignin and cellulose, which is beneficial for subsequent rapid fermentation.

[0007] Furthermore, both the first and second compound formulation strains are high-performance strains selected using high-throughput screening technology. During implementation, flow cytometry is used to sort the cells or particles.

[0008] Furthermore, both the first and second compound formulation strains were first activated by inoculating them onto test tube slant culture at a temperature of 28–35°C and a pH of 7.0. They were then progressively scaled up in flat flasks or shake flasks and seed tanks to obtain a large number of highly active compound strains. The purpose of the first-stage seed culture was to reproduce a large number of vigorous cells. The culture medium should be low in sugar and high in organic nitrogen, and the culture conditions should be designed to promote cell growth. The second-stage seed culture was to further expand the number of cells to achieve a sufficient number of strains required for fermentation.

[0009] Furthermore, the livestock and poultry manure is one or more of chicken manure, sheep manure, cow manure, and pig manure. The first compound formula microbial strain includes one or more of lactic acid bacteria, yeast, Aspergillus niger, Trichoderma, Mucor, Bacillus subtilis, methanogenic bacteria, and thermophilic acidophilic bacteria; the second compound formula microbial strain includes one or more of Bacillus megaterium, Bacillus mucilaginosus, Thiobacillus ferrooxidans, Thiobacillus acidophilus, Stratosporum spp., Bacillus spheroides, Bacillus laterosporus, Streptomyces jingyangensis, and Aspergillus oryzae. The specific planted plants are one or more of water spinach, sweet bamboo shoots, castor beans, elephant grass, and forage grass.

[0010] Furthermore, after the livestock and poultry manure is mixed with the first compound formula microbial inoculum and added to the bioreactor, the pressure is maintained at 0.15 MPa, and sterile air is continuously introduced; during the first 0-12 hours of fermentation, the temperature inside the reactor is controlled at 30℃; during 12-24 hours, the temperature inside the reactor gradually rises and is maintained at 39℃; during 24-48 hours, the temperature inside the reactor slowly decreases and is maintained at 30℃ until fermentation is complete; when the pH of the acidic hydrolysate in the reactor is ≤3.0 and the organic matter content is less than or equal to 40%, fermentation can be considered complete.

[0011] Furthermore, the mass ratio of acidic hydrolysate to red mud is 1:(1.5-5), with the specific ratio determined based on the actual pH of both, ensuring the final mixture pH is controlled between 6.7 and 7.3. The reaction time is approximately 3-6 hours. When the final substrate pH reaches around 7.0 and remains essentially unchanged, the reaction is considered complete. Appropriate stirring should be performed during the reaction. The acidic hydrolysate and red mud undergo an acid-base neutralization reaction. The products of this neutralization reaction can solidify some heavy metal elements in the waste residue mixture, initially reducing the heavy metal ion content. After the sugarcane pith powder undergoes high-temperature cooking to release heat during the neutralization reaction, lignin and cellulose are completely separated. Lignin breaks down from a complex three-dimensional network molecule into multiple smaller molecules with straight-chain structures, which facilitates more efficient decomposition and utilization of lignin and cellulose by microorganisms, greatly improving fermentation decomposition efficiency.

[0012] Furthermore, the thiobacillus-like microorganisms in the second compound formula mainly function to efficiently passivate heavy metal ions, and elemental sulfur is an essential nutrient for their growth and activities. When the heavy metal content of the treated red mud is high, thiobacillus-like microorganisms and 0.05-2% of 150-mesh monoclinic sulfur powder by weight of fermentation substrate are added to the second compound formula to enhance the microorganisms' ability to passivate heavy metal ions.

[0013] According to another aspect of this application, a device for the full-scale biological reclamation of red mud using a biological method is also provided. The device is characterized by employing the aforementioned method and includes: a bioreactor, an integrated water and fertilizer system, and a waste heat recovery system that cooperate with each other. The bioreactor includes: a sterile air pipe, an aeration structure, a heating water jacket, an exhaust port, and a tank. Sterile air is connected from the tank to the aeration structure at the bottom of the reactor. The aeration structure consists of nozzles arranged in a circular pattern at the bottom of the reactor, and the radius of the nozzle arrangement should satisfy 0.4R≤D. 喷 ≤0.5R,D 喷 R is the radius of the nozzle arrangement, and R is the inner radius of the reactor. The shape of the nozzles should meet the following requirements. 0.07R≤a≤0.1R, 0.04R≤b≤0.6R, 0.02R≤c≤0.04R, where a, b, and c are the major, middle, and minor axes of the ellipse, respectively. Circular nozzles are arranged on the nozzle head. x, y, and z represent the three dimensions of the Cartesian coordinate system. The extension of the major axis of the nozzle head passes through the center of the bottom of the tank. The manhole, sight glass, and exhaust port are located at the upper end of the tank. The guide tube is located at the center of the reactor and is trumpet-shaped with a taper of 1:(50~100). The waste heat recovery equipment includes an air compressor waste heat recovery device, a neutralization waste heat recovery device, a hot water storage tank, and a supercritical carbon dioxide heat pump. All recovered waste heat is stored as hot water in the hot water storage tank, which is equipped with a supercritical carbon dioxide heat pump for auxiliary heating. The air compressor waste heat recovery device includes a circulating water pump and a cooling water jacket. The neutralization waste heat recovery device includes a pressure relief valve, a reaction tank, a condenser heat exchanger, a baffle plate, a feed inlet, a stirring shaft, a stirrer, a condenser heat exchanger inlet, a condenser heat exchanger outlet, a discharge port, and a manhole. The pressure relief valve is located on the reaction tank, the condenser heat exchanger is located inside the reaction tank, the stirrer is located inside the reaction tank, and the baffle plate is located between the condenser heat exchanger and the stirrer. The integrated water and fertilizer system includes an aerated fermentation tank, a finished water and fertilizer tank, and drip irrigation tape.

[0014] Furthermore, the reaction vessel body includes an outer shell and a lining. The cross-section of the baffle plate perpendicular to the stirring shaft is V-shaped, with the V-shaped opening of the baffle plate facing upwards.

[0015] By applying the technical solution of this application, soil biological activity is enhanced through microbial inoculants, neutralization reactions, and the addition of soil conditioners or bio-organic fertilizers, thus completing the soilification of red mud. The technical solution of this application effectively solves the problems of wasteful land use and environmental pollution caused by existing red mud dumping methods. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the process flow of the biological red mud full-scale soil biological activity reclamation method of this application is shown;

[0019] Figure 2 A schematic diagram of the internal structure of the neutralization waste heat recovery reactor of the apparatus of this application is shown;

[0020] Figure 3 It shows Figure 2 A three-dimensional structural diagram of the neutralization waste heat recovery reaction vessel;

[0021] Figure 4 It shows Figure 2 A three-view schematic diagram of the neutralization waste heat recovery reactor.

[0022] Figure 5 A schematic diagram of the ejector of the device of this application is shown.

[0023] Figure 6 A schematic diagram of the internal structure of the bioreactor of the device of this application is shown;

[0024] Figure 7 It shows Figure 6 A schematic diagram of the aeration structure of a bioreactor;

[0025] Figure 8 The following is a schematic diagram of the particle swarm optimization algorithm of the method of this application;

[0026] Figure 9 A schematic diagram of the bacterial strain expansion culture process is shown.

[0027] The above figures include the following reference numerals:

[0028] 1. Pressure relief valve; 2. Outer shell of the reaction tank; 3. Lining of the reaction tank; 4. Condensing heat exchanger; 5. Baffle plate; 6. Feed inlet; 7. Stirring shaft; 8. Stirrer; 9. Inlet / outlet of condensing heat exchanger; 10. Discharge port; 11. Manhole; 12. Exhaust port; 13. Feed inlet; 14. Reactor body; 15. Water jacket; 16. Flow guide tube; 17. Aeration structure; 18. Discharge pipe. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways, rotated 90 degrees, or in other orientations, and the spatial relative descriptions used herein will be interpreted accordingly.

[0032] like Figures 1 to 9 As shown in this embodiment, a method for full-scale soil bioactivity reclamation using biological red mud is as follows: First, sugarcane pith powder and red mud are mixed in a certain proportion; then, a first compound formula microbial inoculum is added to livestock and poultry manure, and the mixture is rapidly hydrolyzed in a bioreactor (application publication number: CN116410026A) for 48 hours, becoming an acidic substance under the action of microorganisms; next, the acidic hydrolysate is neutralized with red mud in a neutralization waste heat recovery reaction tank, producing a slurry, which is then filtered (the liquid after solid-liquid separation can be recycled); next, a soil conditioner or bio-organic fertilizer and a second compound formula microbial inoculum are added to the filter mud to increase its organic matter content and soil bioactivity; finally, under the combined action of multiple microorganisms, the regenerated soil meets all indicators after 72 hours, and crops can be planted. By combining fertigation technology (application publication numbers: CN116195418A, CN116283372A) with plant remediation, soil fertility and biological activity can be further improved, and the red mud can be transformed into soil.

[0033] Sugarcane pith powder consists of particles approximately 2 mm in size. The mass ratio of sugarcane pith powder to red mud is (0.3–0.8):1. Mixing sugarcane pith powder with strongly alkaline red mud can dissolve the lignin in the sugarcane pith into smaller molecules, promoting the separation of lignin (difficult for microorganisms to decompose) and cellulose (easily decomposed by microorganisms), which is beneficial for subsequent rapid fermentation.

[0034] The compound formulation strains are high-performance strains selected through high-throughput screening technology. During implementation, flow cytometry (FCM) is used to sort the cells or particles.

[0035] The compound-formulated microbial strain is first activated by inoculating it onto test tube slant agar at 28–35°C and pH 7.0. It is then progressively scaled up through flat flasks, shake flasks, and seed tanks to obtain a large quantity of highly active compound microbial strains. The purpose of primary seed culture is to propagate a large number of vigorous cells; the culture medium should be low in sugar and high in organic nitrogen, with culture conditions designed to promote bacterial growth. Secondary seed culture is used to further expand the cell count, achieving a sufficient population of microorganisms for fermentation.

[0036] Livestock and poultry manure is one or more of chicken manure, sheep manure, cow manure, and pig manure. The first compound formulation of microbial strains includes one or more of lactic acid bacteria, yeast, Aspergillus niger, Trichoderma, Mucor, Bacillus subtilis, methanogenic bacteria, and thermophilic acidophilic bacteria. These strains are engineered strains screened using high-throughput methods. They are capable of targeted hydrolysis of livestock and poultry manure, rapidly producing various organic acids. In practical engineering, different compound microbial strain formulations can be selected according to requirements to achieve aerobic or anaerobic acid production.

[0037] After livestock and poultry manure is mixed with the first compound formula microbial inoculum and added to the bioreactor, the pressure is maintained at 0.15 MPa, and sterile air is continuously introduced. During the first 0–12 hours of fermentation, the temperature inside the reactor is controlled at 30℃; from 12–24 hours, the temperature gradually rises and is maintained at 39℃; from 24–48 hours, the temperature slowly decreases and is maintained at 30℃ until fermentation is complete. Fermentation is considered complete when the pH of the acidic hydrolysate in the reactor is ≤3.0 and the organic matter content is ≤40%.

[0038] The neutralization waste heat recovery reactor mainly consists of a pressure relief valve (1), an outer shell (2), a lining (3), a condenser heat exchanger (4), a baffle plate (5), a feed inlet (6), a stirring shaft (7), a stirrer (8), an inlet / outlet of the condenser heat exchanger (9), a discharge port (10), and a manhole (11). The design pressure is 0.3 MPa, and the design temperature is 300℃. The neutralization waste heat recovery reactor meets the requirements of relevant national standards such as GB / T 150.1-2011 "Pressure Vessels Part 1: General Requirements" and GB / T 150.2-2011 "Pressure Vessels Part 2: Materials".

[0039] The pressure relief valve is located at the top of the tank and automatically opens or closes based on the feedback value from the high-precision pressure sensor inside the tank to prevent excessive pressure. Furthermore, the pressure relief valve must be opened before maintenance, discharging, and feeding to prevent accidents caused by excessive pressure. The reaction tank body consists of an outer shell, an insulation layer, and a lining. Preferably, the outer shell is made of Q345R (4mm thick), the insulation layer is made of vacuum or polyurethane material (3mm thick), and the lining is made of zirconium alloy (Zr-3) (3mm thick). The condenser heat exchanger is located at the top of the tank and adopts a serpentine coil form with fins and a hydrophobic coating. It recovers and neutralizes the heat of the reaction while condensing water vapor and returning it to the reaction tank. The hot water obtained from the condenser heat exchanger can be used for boiler feedwater preheating, temperature control and insulation in bioreactors or microbial culture expansion processes, reducing energy consumption. The baffle plate is located below the heat exchanger to prevent liquid or solid splashing from affecting its performance. The baffle plate employs a combination of V-shaped and inverted V-shaped structures, arranged axially along the tank body and fixed at both ends. Multiple drainage holes are distributed on the sides, and the baffle plate is made of high-temperature and corrosion-resistant material. The V-shaped structure serves two purposes: firstly, it guides steam, making its flow more controllable and creating internal circulation; secondly, this structure facilitates the collection of condensate and prevents its accumulation, allowing it to drain promptly through the small holes on the side of the baffle plate. The stirring device is located in the lower part of the tank, rotating at 10–30 r / min. The tank is equipped with multiple corrosion-resistant, high-precision sensors for pressure, temperature, pH, and other parameters.

[0040] The heat transfer coefficient and area of ​​a coil heat exchanger are determined by the following formula:

[0041]

[0042] In the formula, k is the heat transfer coefficient; A0 is the sum of the tube surface area and the fin surface area; α w —Heat transfer coefficient of the water-side surface inside the pipe;

[0043] A w —Inner surface area of ​​the tube; α0 —Heat transfer coefficient of the air side surface; η s —Surface efficiency.

[0044]

[0045] In the formula, A is the required heat transfer area; Q0 is the heat of neutralization reaction; t a —Gas temperature inside the reaction vessel; t0 —Cooling water temperature; ε —Emissivity of the tube surface, typically taken as 0.95; σ —Blackbody radiation coefficient.

[0046] The mass ratio of acidic hydrolysate to red mud is 1:(1.5-5), with the specific ratio determined based on the actual pH of both, ensuring the final mixture's pH is controlled between 6.7 and 7.3. The reaction time is approximately 3-6 hours. The reaction is considered complete when the final substrate pH reaches around 7.0 and remains essentially unchanged. Appropriate stirring is necessary during the reaction. The acidic hydrolysate and red mud undergo an acid-base neutralization reaction. The products of this neutralization reaction can solidify some heavy metal elements such as As, Pb, and Cr in the waste mixture, initially reducing the heavy metal ion content. Furthermore, after the sugarcane pith powder undergoes high-temperature cooking following the neutralization reaction, lignin and cellulose are completely separated. Lignin breaks down from a complex three-dimensional network molecule into multiple smaller molecules with straight-chain structures, facilitating more efficient microbial decomposition and utilization of lignin and cellulose, significantly improving fermentation efficiency.

[0047] The second compound formulation includes one or more of the following microbial strains: *Bacillus megaterium*, *Bacillus mucilaginosus*, *Thiobacillus ferrooxidans*, *Thiobacillus acidophilus*, *Bacillus isothermalus*, *Bacillus spheroidosa*, *Bacillus laterosporus*, *Streptomyces jingyangensis*, and *Aspergillus oryzae*. These strains are engineered strains selected using high-throughput methods. The preferred mass ratio of bacilli to fungi is 6:4, which not only rapidly passivates heavy metal ions but also enables targeted hydrolysis of agricultural waste, rapidly increasing soil organic matter and biological activity, promoting the formation of large aggregates, increasing particle size, reducing bulk density, and improving the physical structure of red mud.

[0048] The thiobacillus-like microorganisms in the second compound formula mainly function to efficiently passivate heavy metal ions, and elemental sulfur is an essential nutrient for their growth. When the heavy metal content of the red mud being treated is high, thiobacillus-like microorganisms (adjusting the number of microorganisms according to the heavy metal content) and 0.05–2% of 150-mesh monoclinic sulfur powder (adjusting the amount according to the number of microorganisms) can be added to the second compound formula to enhance the microorganisms' ability to passivate heavy metal ions.

[0049] The mass ratio of filter mud (red mud mixture), soil conditioner (or bio-organic fertilizer), and the second compound formula microbial inoculum is 10:(0.5-1.5):(0.2-0.5), so that the moisture content of the mixture is about 50%. During the fermentation process, the mixture should be turned over 2-3 times.

[0050] The detection indicators for red mud soil include: bulk density, pH, organic matter content, heavy metal ion content, and soil respiration intensity. These indicators should meet the following requirements: bulk density ≤ 1.8 g / cm³; pH between 6.5 and 7.5; total organic carbon (TOC) ≥ 10.0 g / kg; heavy metal ion content should not exceed the pollution risk screening value in the "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control" (GB 15618—2018); and daily average soil respiration intensity ≥ 3.6 g / (m²·d).

[0051] After the reclaimed soil is cultivated, a season of crops needs to be planted, preferably water spinach or sweet bamboo shoots. This should be combined with fertigation technology to further improve the soil's biological activity and fertility, ensuring the arable land quality exceeds the standards outlined in the "Land Use Status Classification".

[0052] The standard is Grade 10 in GB / T 21010-2017 or Grade 6 in the "Grading of Cultivated Land Quality" (GB / T 33469-2016). For example, a comprehensive utilization project of red mud by an aluminum company in Guangxi.

[0053] I. Red mud sampling analysis

[0054] The red mud was collected from the aluminum company's red mud stockpile. The sampling method followed the sampling standards specified in the "Technical Specification for Soil Environmental Testing (HJ / T166-2004)". Five sampling points were set up using the quincunx sampling method, and approximately 10 tons of red mud samples were collected from the surface layer (0–20 cm depth). The samples were mixed and transported back to the laboratory. The basic physicochemical properties and heavy metal content of the collected red mud are shown in Tables 1 and 2.

[0055] Table 1 Basic Physicochemical Properties of Red Mud

[0056]

[0057]

[0058] Table 2. Heavy metal ion content in red mud (mg / kg)

[0059] Cu Zn As Pb Cr Mn Cd Ni 35.04 366.79 37.81 280.83 186.49 76.23 0.91 37.28

[0060] According to the "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control" (GB 15618—2018), the heavy metal content in this red mud sample did not exceed the pollution risk control value, but some heavy metals exceeded the pollution risk screening value. This indicates a potential pollution risk, requiring further control measures before crop planting can proceed.

[0061] II. Optimization of the ratio of acid-producing bacteria

[0062] The first compound microbial strain used in this embodiment (with no antagonistic interaction between strains) includes Trichoderma, Aspergillus niger, Bacillus subtilis, yeast, methanogens, and thermophilic acidophilic bacteria. The Trichoderma and Bacillus subtilis in the first compound microbial strain can degrade macromolecular organic matter (such as cellulose, hemicellulose, lignin, etc.) in livestock and poultry manure, breaking it down into easily absorbed nutrients such as glucose. Subsequently, the acid-producing bacteria (Aspergillus niger, yeast, methanogens, and thermophilic acidophilic bacteria) introduced into the reactor convert glucose into organic acids such as citric acid and acetic acid through biochemical reactions, initiating large-scale acid production.

[0063] Experimental plan:

[0064] Step 1: Add the first compound formula microbial strain and livestock and poultry manure into the reactor;

[0065] Step 2: The initial pressure of the reactor is maintained at 0.15 MPa, and sterile air is continuously introduced; during the first 0-12 hours of fermentation, the temperature inside the reactor is controlled at 30℃; during the first 12-24 hours, the temperature inside the reactor gradually rises and is maintained at 39℃; during the first 24-48 hours, the temperature inside the reactor slowly decreases and is maintained at 30℃ until fermentation is completed at 48 hours.

[0066] Step 3: Comparative analysis of the fermentation broth.

[0067] Table 3. Sugar-acid conversion rate and cost data of acid-producing bacteria.

[0068] strains Sugar-acid conversion rate T (%) Production cost (RMB / kg) Aspergillus niger 66 30 yeast 52 15 Methanogens 69 25 Thermophilic acidophilic bacteria 71 34

[0069] Based on practical production experience, a sugar-acid conversion rate (Ts) ≥ 65% is sufficient to meet production standards. To achieve a balance between the acid-producing performance and cost of the compound-formulated microbial agent fermentation, a particle swarm optimization algorithm is used to optimize the microbial formula. With cost minimization as the objective, the microbial formula is optimized to achieve the lowest possible production cost.

[0070] Particle Swarm Optimization (PSO), also known as Particle Swarm Optimization or Birdsong Optimization, is a novel evolutionary algorithm developed in recent years by J. Kennedy and RCEberhart. PSO is a type of evolutionary algorithm that starts with random solutions and iteratively searches for the optimal solution. Fitness is used to evaluate the quality of the solution. It is simpler than genetic algorithms, as it lacks the "crossover" and "mutation" operations of genetic algorithms. It finds the global optimum by following the currently found optimal value. This algorithm has attracted considerable attention in academia due to its ease of implementation, high accuracy, and fast convergence, and has demonstrated its superiority in solving practical problems. PSO is a parallel algorithm. The modeling and optimization process is as follows:

[0071] 1. Establish the objective function

[0072] To minimize costs, an objective function is established.

[0073]

[0074] In the formula, i is the number of microbial strains involved in the formulation, i = 1, 2, 3, 4; xi is the mass percentage of the i-th microbial strain; X is the matrix composed of the mass percentages of each microbial strain, X = [x1, x2, x3, x4]T, X ≥ 0; ki is the production cost of the i-th microbial strain.

[0075] 2. Constraints

[0076] The microbial compound formulation model has three constraints: the ratio constraint keeps the calculated microbial ratio within a reasonable range, and the property constraint ensures that the optimized microbial formulation meets the control indicators.

[0077] (1) Proportioning constraints:

[0078] (2) Upper and lower limits of proportion constraints: X min ≤X≤X max

[0079] (3) Lower limit constraint on sugar-acid conversion rate:

[0080] In constraint (1), h(X) represents the sum of the proportions of each bacterial strain. In constraint (2), X... min and X max —The lower and upper limits of the pre-set ratios of each microbial strain can be obtained from practical production experience. min =[x 1min ,x 2min ,x3min ,x 4min ] T =[0.1,0.1,0.2,0.1] T X min ≥0, X max =[x 1max ,x 2max ,x 3max ,x 4max ] T =[0.3,0.25,0.5,0.2] T X max ≥0. In constraint (3), T i —The sugar-acid conversion rate of the i-th bacterial species, T s —The standard for sugar-acid conversion rate of compound formula strains is 0.66 here.

[0081] 3. Optimization of Constraints

[0082] Since constraint (1) is inconvenient to include in the feasible region, constraint (1) is transformed into a penalty function:

[0083] g(x)=σ(h(X)-1) 2

[0084] In the formula, σ is the penalty coefficient; h(X) is the constraint of the strain formulation model (1).

[0085] The penalty function method is one of the main methods for incorporating constraints that are inconvenient to include in the feasible region into the objective function. According to the "penalty strategy" of the penalty function, the penalty coefficient needs to be set to a very large value to ensure that the constraints take effect. This penalty coefficient σ = 1.0 × 10⁻⁶. 9 .

[0086] 4. Establishment of the final objective function

[0087] With the optimization objectives of achieving the target sugar-acid conversion rate and minimizing total cost, a linear weighted method was used to transform the multi-objective optimization into a single-objective optimization. Combining the objective function and constraints, an augmented objective function was constructed. The final objective function of the microbial compound formulation model is as follows:

[0088]

[0089] In the formula, λ1 and λ2 represent the weights of the sugar-acid conversion rate and production cost in the strain formulation, where λ1 = λ2 = 10; x i —The mass percentage of the i-th bacterial species; T i —The sugar-acid conversion rate of the i-th bacterial species, T s —Standard for sugar-acid conversion rate of compound formula strains, where T is the standard. s =0.66; k i—Production cost of the i-th strain, k min —The target value of the total cost formula, where k is the total cost. min =25; σ—penalty coefficient, here σ=1.0×10 9 .

[0090] 5. Optimization process and results

[0091] like Figure 8 As shown, all particles in the space are first assigned initial random positions and initial random velocities. Then, the position of each particle is advanced sequentially based on its velocity, the known optimal global position in the space, and the particle's optimal position. As the calculation iterates, by exploring and utilizing known advantageous positions in the search space, the particles will gather near one or more optimal points.

[0092] Its core idea is to utilize the sharing of information among individuals in a group to enable the movement of the entire group to evolve from disorder to order in the problem-solving space, thereby obtaining a feasible solution to the problem.

[0093] In each iteration, after finding two optimal values ​​(pbest, gbest), the particle updates its velocity and position using the following formula.

[0094] v i =ωv i +c1·rand()·(pbest i -x i )+c2·rand()·(gbest i -x i )

[0095] That is, the velocity of the i-th particle in this step = its own velocity inertia in the previous step + self-cognition part + social cognition part

[0096] x i =x i +v i

[0097] That is, the position of the i-th particle in the next step = its current position + its current velocity * the time of motion.

[0098] In the formula, vi is the particle's velocity; rand() is a random number between (0,1); xi is the particle's position; c1 and c2 are the individual learning factor and the social learning factor, respectively; ω is the inertia factor, and the larger its value, the stronger the global optimization ability; pbest i It is the best position that the i-th particle passes through; gbest is the best position that all particles pass through.

[0099] The particle swarm size is set to N=20, the dimension of each particle is n=4, the upper limit of the number of iterations is Loop=1000, the learning factors are c1=c2=2, and the inertia factor ω adopts a non-linear decreasing strategy.

[0100] The optimal ratio of acid-producing bacteria is shown in the table below.

[0101] Table 4. Optimal ratio of acid-producing bacteria after optimization by particle swarm optimization algorithm.

[0102] strains Quality percentage (%) Aspergillus niger 13 yeast 24 Methanogens 43 Thermophilic acidophilic bacteria 20

[0103] After optimization, the cost of the acid-producing bacteria agent is 25 yuan / kg, and the sugar-acid conversion rate is 65%.

[0104] The existing acid-producing bacteria ratios, summarized based on production experience, are shown in the table below.

[0105] Table 5 Existing acid-producing bacteria ratios

[0106] strains Quality percentage (%) Aspergillus niger 15 yeast 22 Methanogens 39 Thermophilic acidophilic bacteria 24

[0107] The existing acid-producing bacteria agent costs 25.7 yuan / kg, with a sugar-acid conversion rate of 65%. Therefore, after optimization using particle swarm optimization, the unit cost of the acid-producing bacteria agent is reduced by 2.8% while maintaining the same sugar-acid conversion rate.

[0108] III. Optimization of Compound Microbial Agent Formulation

[0109] In experiments and production, it was found that within a certain range, the final fermentation acid production result is not sensitive to the specific proportion of each aerobic bacterium. The optimal ratio is determined to be mold: Bacillus = 1:1.2.

[0110] Based on the optimal ratio of acid-producing bacteria and aerobic bacteria determined by particle swarm optimization, an extreme vertex mixing experimental design method with upper and lower limit controls was adopted to obtain a mixing experimental scheme to determine the ratio of aerobic bacteria to acid-producing bacteria. Upper and lower limits for each factor were set based on production practice (each component in the formula is expressed as a mass fraction): the mass ratio of aerobic bacteria was 0–40%, and the mass ratio of acid-producing bacteria was 60–100%. Five treatments were designed for the experiment. One kg of pig manure sample was weighed, and 5% of the pig manure mass was added to a compound inoculant with different ratios of aerobic and acid-producing bacteria. The mixtures were fermented in the same bioreactor for 48 hours.

[0111] Table 6. Composition of pig manure samples used in the experiment

[0112]

[0113] Table 7. Fermentation results of aerobic and acid-producing bacteria with different ratios.

[0114] Serial Number aerobic bacteria mass ratio (%) Acid-producing bacteria mass ratio (%) pH after fermentation 1 0％ 100％ 3.55 2 10％ 90％ 3.01 3 20％ 80％ 2.94 4 30％ 70％ 2.88 5 40％ 60％ 2.99

[0115] Therefore, for this pig manure sample, the optimal mass ratio of aerobic bacteria and acid-producing bacteria in the first compound formula is 30% and 70%, respectively. The mass ratio (%) of Aspergillus niger, yeast, Trichoderma, Bacillus, thermophilic acidophilic bacteria, and methanogenic bacteria in the first compound formula is 9:17:14:16:14:30.

[0116] IV. Red mud soil transformation and its results

[0117] A device for the full-scale biological reclamation of red mud using biological methods includes: a bioreactor, an integrated water and fertilizer system, and a waste heat recovery system that work together.

[0118] The main components of the bioreactor include: an exhaust port 12, a feed inlet 13, the reactor body 14, a water jacket 15, a guide tube 16, an aeration structure 17, and a discharge pipe 18. The aeration structure 17 and the discharge pipe 18 are located at the bottom of the reactor. The aeration structure 17 consists of nozzles arranged in a circular pattern at the bottom of the reactor and connected to a sterile air storage tank via pipes. The radius of the nozzle arrangement should satisfy 0.4R ≤ D. 喷 ≤0.5R,D 喷 R is the radius of the nozzle arrangement, and R is the inner radius of the reactor. The shape of the nozzles should meet the following requirements. 0.07R≤a≤0.1R, 0.04R≤b≤0.6R, 0.02R≤c≤0.04R, where a, b, and c are the major, middle, and minor axes of the ellipse, respectively. Circular nozzles are arranged on the nozzle head. x, y, and z represent the three dimensions of the Cartesian coordinate system. The extension of the major axis of the nozzle passes through the center of the bottom of the tank. The exhaust port 12 and the feed port 13 are located at the upper end of the tank. The guide tube 16 is located at the center of the bottom circle of the reactor. Its upper port is at a predetermined distance from the upper inner wall of the reactor body 14, and its lower port is at a predetermined distance from the lower inner wall of the reactor body 14. The guide tube 16 is trumpet-shaped with a taper of 1:(50~100), resulting in better mass transfer. The reactor body 14 is externally enclosed by a water jacket 15, which allows for adjustment of the internal medium composition and temperature to heat or cool the reactor as needed.

[0119] The waste heat recovery equipment includes an air compressor waste heat recovery unit, a neutralization waste heat recovery unit, a hot water storage tank, and a supercritical carbon dioxide heat pump. The air compressor waste heat recovery unit includes a circulating water pump and a cooling water jacket. The air compressor is externally encased in the cooling water jacket, which is connected to the hot water storage tank via pipes and the circulating water pump. The neutralization waste heat recovery unit, also known as a neutralization waste heat recovery reaction tank, includes: a pressure relief valve 1, an outer shell 2, a lining 3, a condenser heat exchanger 4, a baffle plate 5, a feed inlet 6, a stirring shaft 7, a stirrer 8, a condenser heat exchanger inlet / outlet 9, and a discharge port 10. The reaction tank body includes the outer shell 2 and the lining 3. The pressure relief valve 1 is located at the top of the reaction tank body. The feed inlet 6 is located on the upper left side of the reaction tank body. The condenser heat exchanger inlet / outlet 9 is located at the upper part of the reaction tank body, and the condenser heat exchanger 4 is located at the upper part of the reaction tank body. A stirrer 8 is located at the bottom of the reaction tank and is powered by a stirring shaft 7, with a rotation speed of 10–30 r / min. The tank is equipped with multiple corrosion-resistant, high-precision sensors for pressure, temperature, and pH. A baffle plate 5 is positioned between the condenser heat exchanger 4 and the stirrer 8. The cross-section of the baffle plate 5, perpendicular to the stirring shaft 7, is V-shaped, with the V-shaped opening facing upwards. The discharge port 10 is located at the bottom of the reactor tank. The waste heat recovered by the above equipment is stored as hot water in a hot water storage tank. A heat exchanger is installed at the outlet of the hot water storage tank, connected to the gas cooler of a supercritical carbon dioxide heat pump for auxiliary heating. The hot water storage tank is connected to a sterile air storage tank and a bioreactor via pipes and a mixing valve, through a water jacket. The temperature is regulated by controlling the water temperature. One inlet of the mixing valve is connected to the outlet of the hot water storage tank, and the other inlet is connected to room temperature cooling water. The outlet water temperature is controlled by adjusting the valve opening.

[0120] The integrated water and fertilizer system includes an aerated fermentation tank, a fertigation product tank, and drip irrigation tape. The aerated fermentation tank is connected to the exhaust port 12 of the bioreactor, through which an air compressor, an air filter, an air compressor, and an ejector are connected in sequence. The ejector draws filtered bioreactor exhaust gas, while the injected stream is filtered fresh air. The aerated fermentation tank, the fertigation product tank, and the drip irrigation tape are connected in sequence via pipelines.

[0121] The 10 tons of red mud was divided into 10 batches, with 1 ton per batch, for treatment. Taking the soilization process of the 5th batch of red mud as an example, the detailed steps are as follows:

[0122] Step 1: After adding 250 kg of pig manure and 10 kg of the first compound formula inoculum to the feed inlet 13 of the bioreactor, maintain the initial pressure of the reactor at 0.15 MPa, and continuously introduce sterile air through the aeration structure 17. During the first 0-12 hours of fermentation, the temperature inside the reactor is controlled at 30℃ using the water jacket 15; from 12-24 hours, the temperature is gradually increased using the water jacket 15 and maintained at 39℃; from 24-48 hours, the temperature is slowly decreased using the water jacket 15 and maintained at 30℃ until fermentation is complete after 48 hours. The fermentation substrate forms an internal circulation under the action of airflow and the guide tube 16, and rapidly hydrolyzes into acidic substances within the bioreactor after 48 hours. The exhaust gas discharged from the bioreactor exhaust port 12 is pressurized by an air compressor and then passes through an air filter to remove most of the microorganisms. After being pressurized again by an air compressor, the filtered exhaust gas is mixed with fresh air under the action of an ejector to form a uniform high-speed, high-pressure airflow. This airflow is then introduced into the aeration fermentation tank for the fermentation of organic water-soluble fertilizer.

[0123] Step 2: The acidic hydrolysate of livestock and poultry manure after fermentation in the bioreactor is fed into the inlet 6 of the neutralization waste heat recovery reactor, where it undergoes a neutralization reaction with a 1.5t mixture of red mud and sugarcane pith (red mud: sugarcane pith = 2:1), releasing heat. The stirrer 8 operates at a speed of 20 r / min. When the pH of the reactants reaches approximately 7.0 and remains essentially constant, the reaction is considered complete, and the reactants are discharged through the outlet 10.

[0124] Step 3: After the neutralization reaction is completed, the red mud mixture is filtered to produce filter mud, which is then sent to a fermentation tank. 30 kg of the second compound formula bacteria and 100 kg of bio-organic fertilizer (authorization number: CN112159051B) are added for fermentation to increase its organic matter content and soil biological activity.

[0125] Step 4: Finally, after 72 hours of combined action by multiple microorganisms, the red mud is initially soilified and ready for reclamation. During the plant planting and restoration process, the fermented organic water-soluble fertilizer in the septic tank is applied to the initially soilified red mud through drip irrigation.

[0126] During the above operation, all air compressors are equipped with cooling water jackets, and the waste heat recovery reaction tank is equipped with a heat exchanger. The heat generated by these devices is carried away by cooling water and stored in a hot water storage tank, which is equipped with a supercritical carbon dioxide heat pump for auxiliary heating. The hot water in the storage tank is used to heat the sterile air and control the temperature of the bioreactor. The control strategy is as follows:

[0127] (1) When the temperature of the hot water in the storage tank is lower than the required supply temperature (t) 罐 <t 供This means the waste heat is insufficient to heat the sterile air and the bioreactor. The supercritical carbon dioxide heat pump is turned on, the cold water mixing valve is closed, and the hot water mixing valve is opened. The refrigerant flow rate is controlled by adjusting the heat pump's throttling device, thereby controlling the hot water temperature.

[0128]

[0129] t 供 =t 设 +Δt

[0130] In the formula, m R —Refrigerant flow rate, h gc，in and h gc，out —These represent the enthalpy values ​​of the refrigerant at the inlet and outlet of the gas cooler, respectively, c w —Specific heat capacity of water, m w —Hot water flow rate, t 供 —The temperature of the supplied hot water, t 罐 —Temperature of hot water in the storage tank, t 设 — Set temperature, Δt — heat exchange temperature difference, taken as 5℃.

[0131] (2) When the temperature of the hot water in the storage tank is greater than or equal to the required supply temperature (t) 罐 ≥t 供 This means that the waste heat can meet the needs of heating sterile air and the bioreactor. At this point, the supercritical carbon dioxide heat pump is turned off, and the water supply temperature is adjusted by regulating the opening of the hot water and cold water valves of the mixing valve.

[0132] In this embodiment, the room temperature is 27°C, the hot water storage tank capacity is 200L, the water temperature inside the tank is 40°C, the hot water flow rate is 60L / min, the supercritical carbon dioxide heat pump has a rated power of 1000W and a heating capacity of 2900W.

[0133] During the 0-12 hour stage of fermentation in step 1, the temperature of the hot water in the storage tank is greater than or equal to the required supply temperature (t). 罐 ≥t 供 (2) The water supply temperature is adjusted by controlling the opening of the mixing valve.

[0134] During the first 12-24 hours of fermentation in step 1, the temperature of the hot water in the tank is lower than the required supply temperature (t). 罐 <t 供 ), and adopt control strategy (1) to start the supercritical carbon dioxide heat pump. According to the carbon dioxide property table, the inlet and outlet enthalpy values ​​of the air cooler are 459.72 KJ / Kg and 416.63 KJ / Kg, respectively.

[0135] t 供 =t 设+Δt=39+5=44℃

[0136]

[0137] During the initial 24-48 hours of fermentation in step 1, control strategy (1) was adopted, adjusting the refrigerant flow rate once per hour to ensure a temperature drop of 1°C per hour. After 4 hours, the heat pump was shut off, and control strategy (2) was adopted thereafter to control the temperature of the supplied hot water at 35°C.

[0138] After the red mud soil was converted into soil, a series of experiments and tests were conducted, and the results are as follows.

[0139] Table 8. Basic physicochemical properties of red mud after biological treatment.

[0140] Testing items Test results pH 7.34 Total organic carbon (TOC), g / kg 10.06 Available phosphorus, mg / kg 33.76 Available potassium, mg / kg 31.28 Total nitrogen, mg / kg 270.56 <![CDATA[Bulk density, g / cm 3 > 1.65 <![CDATA[Daily average soil respiration intensity, g / (m 2 ·d)]]> 5.4

[0141] Table 9. Heavy metal ion content (mg / kg) of red mud after biological treatment.

[0142] Cu Zn As Pb Cr Mn Cd Ni 52.16 196.54 18.20 2.60 101.51 53.64 0.06 12.70

[0143] Table 10 Germination rate of water spinach seeds

[0144] Planting substrate Germination rate Untreated red mud 0％ Red mud treated by biological method 81％

[0145] The above data demonstrates that the red mud treated by the microbial method significantly improved the daily average soil respiration intensity, organic matter, and nutrient element content, while also substantially reducing bulk density, indicating a substantial improvement in the physical and chemical structure of the soil. Furthermore, the heavy metal content of the red mud treated by the microbial method was all below the pollution risk screening values ​​in the "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control" (GB 15618-2018), meaning that the risk of heavy metals in the soil to agricultural product quality and safety, crop growth, or the soil ecological environment is low and generally negligible. Using the method provided by this invention, the extreme physical and chemical properties of the red mud were improved, increasing the germination rate of water spinach seeds from 0% to 81%, making it highly suitable for plant growth. This facilitates further phytoremediation of red mud (planting water spinach) to improve soil fertility and biological activity, and enhances the stability of soil aggregate structure. The quality of cultivated land reaches level 10 in the "Land Use Status Classification" (GB / T 21010-2017) standard or level 6 in the "Cultivated Land Quality Grade" (GB / T33469-2016) standard, ultimately achieving full-scale reclamation of red mud with complete soil biological activity.

[0146] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0147] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0148] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for the full-scale biological reclamation of red mud using biological methods, characterized in that, Includes the following steps: S10 Mix sugarcane pith powder and red mud in a certain proportion; S20 introduces livestock and poultry manure and the first compound formula microbial strain into the bioreactor, continuously introducing sterile air while maintaining a certain temperature and pressure. The fermentation substrate forms an internal circulation under the action of airflow and guide tube, becoming acidic substances under the action of microorganisms. Simultaneously, the exhaust gas discharged from the bioreactor passes through a primary air compressor, an air filter, a secondary air compressor, and an ejector, mixing with fresh air to form a high-speed, high-pressure jet, which is then introduced into the aerated fermentation tank for the fermentation of organic water-soluble fertilizer. The first compound formula microbial strain has an optimized ratio of acid-producing bacteria and aerobic bacteria based on particle swarm optimization. The mass percentage (%) of Aspergillus niger, yeast, Trichoderma, Bacillus, thermophilic acidophilic bacteria, and methanogenic bacteria in the first compound formula microbial strain is 9:17:14:16:14:

30. S30 neutralizes acidic hydrolysate and red mud in a neutralization waste heat recovery reactor, producing a slurry, which is then filtered to generate filter mud. S40 Add soil conditioner or bio-organic fertilizer and second compound formula microbial strain to filter mud to improve its organic matter content and soil biological activity. The mass ratio of bacilli and fungi in the second compound formula microbial strain is 6:

4. With the combined action of various microorganisms, S50 regenerated soil meets all indicators and can be combined with fertigation technology to plant specific plants to further improve the biological activity of the soil and complete soil transformation. The optimization process of the particle swarm optimization algorithm is as follows: Establish the objective function: In the formula, i is the number of microbial strains involved in the formulation, i = 1, 2, 3, 4; xi is the mass percentage of the i-th microbial strain; X is the matrix composed of the mass percentages of each microbial strain, X = [x1, x2, x3, x4]T, X ≥ 0; ki is the production cost of the i-th microbial strain. Constraints: The microbial compound formulation model has three constraints: the ratio constraint keeps the calculated microbial ratio within a reasonable range, and the property constraint ensures that the optimized microbial formulation meets the control indicators. (1) Proportioning constraints: (2) Upper and lower limits of the ratio constraint: (3) Lower limit constraint of sugar-acid conversion rate: In constraint (1), h(X) represents the sum of the proportions of each bacterial strain; in constraint (2), X... min and X max —The lower and upper limits of the pre-set ratios of each microbial strain can be obtained from practical production experience. min =[x 1 min , x 2 min , x 3 min , x 4 min ] T =[0.1, 0.1, 0.2, 0.1] T X min ≥0, X max =[x 1 max , x 2 max , x 3 max , x 4 max ] T =[0.3, 0.25, 0.5, 0.2] T X max ≥0; T in constraint (3) i —The sugar-acid conversion rate of the i-th bacterial species, T s —The standard for sugar-acid conversion rate of the compound formula strain is 0.66 here; Optimize constraints: Since constraint (1) is inconvenient to include in the feasible region, constraint (1) is transformed into a penalty function: In the formula, σ is the penalty coefficient; h(X) is the constraint of the strain formulation model (1); The penalty function method is one of the main methods for incorporating constraints that are inconvenient to include in the feasible region into the objective function. According to the "penalty strategy" of the penalty function, the penalty coefficient needs to be set to a very large value to ensure that the constraints take effect. This penalty coefficient σ = 1.0 × 10⁻⁶. 9 ; The final objective function is established as follows: With the optimization objectives of achieving the target sugar-acid conversion rate and minimizing total cost, a linear weighted method was used to transform the multi-objective optimization into a single-objective optimization. An augmented objective function was constructed by combining the objective function and constraints. The final objective function of the microbial compound formulation model is: In the formula, λ1 and λ2 represent the weights of the sugar-acid conversion rate and production cost in the strain formulation, where λ1 = λ2 = 10; x i —The mass percentage of the i-th bacterial species; T i —The sugar-acid conversion rate of the i-th bacterial species, T s —Standard for sugar-acid conversion rate of compound formula strains, where T is the standard. s =0.66; k i —Production cost of the i-th strain, k min —The target value of the total cost formula, where k is the total cost. min =25; σ—penalty coefficient, here σ=1.0×10 9 ; Optimization process and results: First, all particles in the space are assigned initial random positions and initial random velocities. Then, based on each particle's velocity, the known optimal global position in the space, and the particle's optimal position, the position of each particle is advanced sequentially. As the calculation progresses and iterates, by exploring and utilizing known advantageous positions in the search space, the particles will gather near one or more optimal points. Its core idea is to use the sharing of information among individuals in a group to enable the movement of the entire group to evolve from disorder to order in the problem-solving space, thereby obtaining a feasible solution to the problem; In each iteration, after finding two optimal values ​​(pbest, gbest), the particle updates its velocity and position using the following formula; That is, the velocity of the i-th particle in this step = its own velocity inertia from the previous step + its self-cognition component + its social cognition component. That is, the position of the i-th particle in the next step = its current position + its current velocity * the time of motion. In the formula, vi is the particle's velocity; rand() is a random number between (0,1); xi is the particle's position; c1 and c2 are the individual learning factor and the social learning factor, respectively; ω is the inertia factor, and the larger its value, the stronger the global optimization ability; pbest i It is the best position that the i-th particle passes through; gbest is the best position that all particles pass through. The particle swarm size is set to N=20, the dimension of each particle is n=4, the upper limit of the number of iterations is Loop=1000, the learning factor is c1=c2=2, and the inertia factor ω adopts a non-linear decreasing strategy.

2. The method for full-scale biological reclamation of red mud using biological methods according to claim 1, characterized in that, Sugarcane pith powder consists of particles of about 2mm. The mass ratio of sugarcane pith powder to red mud is (0.3~0.8):

1. Mixing sugarcane pith powder with strongly alkaline red mud can dissolve the lignin in sugarcane pith into small molecules, promote the separation of lignin and cellulose, and facilitate subsequent rapid fermentation.

3. The method for full-scale biological reclamation of red mud using biological methods according to claim 2, characterized in that, Both the first and second compound formulation strains are high-performance strains selected through high-throughput screening technology. During implementation, flow cytometry is used to sort the cells or particles.

4. The method for full-scale biological reclamation of red mud using biological methods according to claim 3, characterized in that, Both the first and second compound bacterial strains were first activated by inoculating them onto test tube slant culture at a temperature of 28-35℃ and a pH of 7.

0. They were then gradually scaled up through flat flasks, shake flasks, and seed tanks to obtain a large number of highly active compound bacterial strains. The purpose of the first-stage seed culture was to reproduce a large number of vigorous bacteria. The culture medium should be low in sugar and high in organic nitrogen, and the culture conditions should be designed to promote bacterial growth. Secondary seed culture is used to further increase the number of microorganisms to achieve a sufficient number of microbial populations required for fermentation.

5. The method for full-scale biological reclamation of red mud using biological methods according to claim 1, characterized in that, The livestock and poultry manure is one or more of chicken manure, sheep manure, cow manure, and pig manure; the first compound formula of microorganisms includes multiple of lactic acid bacteria, yeast, Aspergillus niger, Trichoderma, Mucor, Bacillus subtilis, methanogenic bacteria, and thermophilic acidophilic bacteria; the second compound formula of microorganisms includes multiple of Bacillus megaterium, Bacillus mucilaginosus, Thiobacillus ferrooxidans, Thiobacillus acidophilus, Stratosporum, Bacillus spheroidum, Bacillus laterosporus, Streptomyces jingyangensis, and Aspergillus oryzae; the specific plant to be planted is one or more of water spinach, sweet bamboo shoots, castor beans, elephant grass, and forage grass.

6. The method for full-scale biological reclamation of red mud using biological methods according to claim 5, characterized in that, After the livestock and poultry manure is mixed with the first compound formula microbial strain and added to the bioreactor, the pressure is maintained at 0.15 MPa, and sterile air is continuously introduced. During the first 0-12 hours of fermentation, the temperature inside the reactor is controlled at 30℃; during 12-24 hours, the temperature inside the reactor gradually rises and is maintained at 39℃; during 24-48 hours, the temperature inside the reactor slowly decreases and is maintained at 30℃ until fermentation is complete; when the pH of the acidic hydrolysate in the reactor is ≤3.0 and the organic matter content is less than or equal to 40%, fermentation is considered complete.

7. The method for full-scale biological reclamation of red mud using biological methods according to claim 6, characterized in that, The mass ratio of the acidic hydrolysate to the red mud is 1:(1.5~5), with the specific ratio determined based on the actual pH of both, ensuring the final mixture pH is controlled between 6.7 and 7.

3. The reaction time is approximately 3~6 hours. The reaction is considered complete when the final substrate pH reaches around 7.0 and remains essentially unchanged. Appropriate stirring is required during the reaction. The acidic hydrolysate and red mud undergo an acid-base neutralization reaction. The products of this neutralization reaction can solidify some heavy metal elements in the waste residue mixture, initially reducing the heavy metal ion content. After the sugarcane pith powder undergoes high-temperature cooking to release heat during the neutralization reaction, lignin and cellulose are completely separated. The lignin breaks down from a complex three-dimensional network molecule into multiple smaller molecules with straight-chain structures, which facilitates more efficient decomposition and utilization of lignin and cellulose by microorganisms, greatly improving fermentation decomposition efficiency.

8. The method for full-scale biological reclamation of red mud using biological methods according to claim 7, characterized in that, The thiobacillus-like microorganisms in the second compound formula mainly function to efficiently passivate heavy metal ions, and elemental sulfur is an essential nutrient for their growth. When the heavy metal content of the treated red mud is high, thiobacillus-like microorganisms and 0.05-2% of 150-mesh monoclinic sulfur powder by weight of fermentation substrate are added to the second compound formula to improve the microorganisms' ability to passivate heavy metal ions.

9. A device for the full-scale biological reclamation of red mud using a biological method, characterized in that, The device employs the method described in any one of claims 1 to 8, and the device comprises: a bioreactor, an integrated water and fertilizer system, and a waste heat recovery system that cooperate with each other; The bioreactor includes: a sterile air pipe, an aeration structure, a heating water jacket, an exhaust port, and a tank. Sterile air is supplied from the tank to the aeration structure at the bottom of the reactor. The aeration structure consists of nozzles arranged in a circular pattern at the bottom of the reactor, with the radius of the nozzle arrangement satisfying 0.4R ≤ D. 喷 ≤0.5R,D 喷 R is the radius of the nozzle arrangement, and R is the inner radius of the reactor. The shape of the nozzles should meet the following requirements. , 0.07R≤a≤0.1R, 0.04R≤b≤0.6R, 0.02R≤c≤0.04R, where a, b, and c are the major, middle, and minor axes of the ellipse, respectively. Circular nozzles are arranged on the nozzle, and the extension line of the major axis of the nozzle passes through the center of the bottom of the tank. The manhole, sight glass, and exhaust port are located at the upper end of the tank. The guide tube is located at the center of the reactor, is trumpet-shaped, and has a taper of 1:(50~100). The waste heat recovery equipment includes an air compressor waste heat recovery device, a neutralization waste heat recovery device, a hot water storage tank, and a supercritical carbon dioxide heat pump. All recovered waste heat is stored in the hot water storage tank in the form of hot water. The hot water storage tank is equipped with a supercritical carbon dioxide heat pump for auxiliary heating. The air compressor waste heat recovery device includes a circulating water pump and a cooling water jacket. The neutralization waste heat recovery device includes: a pressure relief valve, a reaction tank, a condenser heat exchanger, a baffle plate, a feed inlet, a stirring power shaft, a stirrer, a condenser heat exchanger inlet, a condenser heat exchanger outlet, a discharge port, and a manhole. The pressure relief valve is installed on the reaction tank, the condenser heat exchanger is installed inside the reaction tank, the stirrer is installed inside the reaction tank, and the baffle plate is installed between the condenser heat exchanger and the stirrer. The integrated water and fertilizer equipment includes an aeration fermentation tank, a water and fertilizer product tank, and drip irrigation tape.

10. The apparatus for full-scale biological reclamation of red mud using biological methods according to claim 9, characterized in that, The reaction vessel includes an outer shell and a lining. The cross-section of the baffle plate perpendicular to the stirring shaft is V-shaped, with the V-shaped opening facing upwards.

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