Preparation method of coal-based solid waste-based microbial composite repair material

Abstract

This invention discloses a method for preparing a coal-based solid waste-based microbial composite remediation material, belonging to the technical field of soil remediation material preparation and high-value utilization of industrial solid waste. The method includes four core steps: low-damage pretreatment of coal-based solid waste, low-concentration alkali-ultrasound synergistic mild pre-activation, in-situ directional acclimatization-biological secondary activation integrated treatment, microenvironment enhancement, and low-temperature binder-free molding. This invention breaks the technical bias of existing technologies that involve "high-strength modification first, then passive loading of microorganisms," transforming the conflict between solid waste activation modification and microbial compatibility acclimatization into a synergistic process, fundamentally resolving the core technical contradiction between solid waste activation efficiency and microbial survival requirements. The material prepared by this invention possesses both excellent pollutant adsorption and passivation capabilities and long-term microbial activity, and can be widely applied in the field of heavy metal contaminated soil remediation, while simultaneously achieving the harmless and high-value utilization of coal-based solid waste.

Description

Technical Field

[0001] This invention relates to the field of soil remediation material preparation and high-value utilization of industrial solid waste, and particularly to a method for preparing a coal-based solid waste-based microbial composite remediation material. Background Technology

[0003] Preparing coal-based solid waste into microbial composite remediation materials to achieve "waste-to-waste" treatment is an important direction for its high-value utilization. Coal-based solid waste, after modification, has excellent adsorption properties, while microbial remediation has the advantages of being environmentally friendly and low-cost. The synergy of the two can achieve multifunctional soil remediation, but existing technologies still have core bottlenecks.

[0004] The core idea of ​​existing technology is "high-intensity modification first, followed by passive loading of microorganisms." However, the industry has a bias that "the stronger the modification, the better the repair effect," ignoring the survival requirements of microorganisms and falling into a vicious cycle of "the stronger the modification, the worse the microbial activity." The main drawbacks are as follows:

[0005] First, high-intensity modification processes such as high-temperature calcination and high-concentration acid and alkali treatments can damage the nutrient components of solid waste, cause extreme pH levels in the carrier, and result in an unreasonable pore structure, leading to low microbial survival rates and the inability to colonize for a long time.

[0006] Secondly, the two-step method of "modification first, loading later" breaks the synergy between the two, the strains are not oriented for domestication, have poor adaptability and are easy to fall off, and the encapsulation method will block the pores and the physical adsorption method has low activity.

[0007] Third, the process has poor universality and insufficient batch stability, making it unable to adapt to solid waste from different sources, and its performance fluctuates greatly during large-scale production.

[0008] Fourth, the material has limited repair function, insufficient long-term effectiveness and safety, cannot cope with complex pollution, and poses a risk of invasion by exogenous bacteria.

[0009] In summary, existing methods cannot resolve the core contradiction between solid waste modification and microbial adaptation, have many inherent defects, and cannot meet the needs of industrial mass production and complex site remediation. There is an urgent need for new preparation methods. Summary of the Invention

[0010] In view of the above-mentioned defects and core technical contradictions in the existing technology, the purpose of this invention is to provide a method for preparing coal-based solid waste-based microbial composite remediation materials. This method completely breaks the technical bias of the existing technology of "first high-strength modification, then passive loading of microorganisms", and transforms the activation modification of coal-based solid waste and the adaptation and domestication of microorganisms from opposition to synergy. It fundamentally resolves the core technical contradiction between the activation efficiency of solid waste and the survival requirements of microorganisms. At the same time, it takes into account the stability of large-scale production of materials, multi-functional synergistic remediation capabilities and ecological safety, and realizes the organic unity of harmless and high-value utilization of coal-based solid waste and long-term soil remediation.

[0011] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a method for preparing a coal-based solid waste-based microbial composite remediation material, comprising the following steps:

[0012] Step 1: Low-damage pretreatment of coal-based solid waste: Select coal-based solid waste raw materials, and process them through natural air drying, crushing and screening, magnetic separation for impurity removal, water washing and desalination, and low-temperature drying to obtain pretreated solid waste powder.

[0013] Specifically, the core objective of step one is to remove harmful impurities from coal-based solid waste while fully preserving the natural organic carbon and mineral nutrients that can be utilized by microorganisms. This avoids introducing extreme environmental stress during the pretreatment stage and lays the foundation for subsequent microbial adaptation. The entire process involves no high-temperature calcination or strong acid / alkali treatment, achieving low-damage pretreatment of coal-based solid waste.

[0014] Furthermore, the coal-based solid waste raw material is any one or a mixture of two or more of coal gangue, fly ash, coal gasification slag, and coal washing slurry in any proportion, which can be adapted to coal-based solid waste from different sources and has excellent raw material universality.

[0015] Furthermore, the crushing and screening process specifically involves: coarsely crushing the naturally air-dried coal-based solid waste using a jaw crusher, then finely grinding it using a ball mill, and passing it through an 80-120 mesh standard sieve to remove large particle impurities, ensuring that the solid waste powder has a suitable specific surface area, thus providing a basis for subsequent activation.

[0016] Furthermore, the magnetic separation for impurity removal employs a wet magnetic separator with a magnetic field strength of 1000-1500 Gs, used to remove ferromagnetic impurities from the solid waste powder and reduce the inhibitory effect of iron ions on subsequent microbial metabolism.

[0017] Furthermore, the water washing desalination involves washing the sieved solid waste powder 2-3 times with deionized water, stirring for 10-15 minutes each time, and using a plate and frame filter press for solid-liquid separation until the conductivity of the washing liquid is ≤300μS / cm. This process is used to remove soluble salts, dust, and surface exchangeable heavy metals from the surface of the solid waste powder, thereby reducing subsequent salinity and heavy metal stress.

[0018] Furthermore, the low-temperature drying adopts a hot air circulating oven with a drying temperature of 60-80℃, drying until the moisture content of the pretreated solid waste powder is ≤10%. Low-temperature drying can avoid the decomposition of natural organic carbon and nutrient components in solid waste by high temperature, and fully preserve its nutrient supply capacity.

[0019] Step 2: Low-concentration alkali-ultrasound synergistic mild pre-activation: Prepare a low-concentration alkali activation buffer solution, mix the pretreated solid waste powder with the activation buffer solution according to the preset liquid-solid ratio, and perform ultrasonic synergistic activation treatment at room temperature. After activation, adjust the pH of the system to the neutral range in situ, add calcium-based bentonite to construct a long-term pH buffer system, and obtain the pre-activated solid waste carrier after solid-liquid separation, water washing, and low-temperature drying.

[0020] Specifically, the core objective of step two is to gently dissociate the layered crystal lattice of inert minerals such as kaolinite and illite in coal-based solid waste, precisely construct a microbial-friendly hierarchical porous structure, and simultaneously regulate the pH and salinity of the system to build a long-term buffer system. This achieves the simultaneous completion of "enhanced activation efficiency" and "construction of basic microbial compatibility," thoroughly solving the core problems of pH extremes, unreasonable pore structures, and nutrient component destruction caused by the high-intensity modification of existing technologies. The gentle pre-activation process used in this step only performs preliminary crystal lattice dissociation and pore construction on the solid waste, retaining most of the mineral structure and nutrient components, reserving space for subsequent secondary biological activation, and avoiding microbial stress caused by excessive modification.

[0021] Furthermore, the low-concentration alkaline activation buffer is a sodium hydroxide solution with a mass concentration of 1-3%, and 0.5-1% humic acid is added to the activation buffer. The liquid-to-solid ratio of the pretreated solid waste powder to the activation buffer is 1.5-2:1, in mL / g. The sodium hydroxide concentration used in this invention is much lower than the 5-15% concentrated alkali used in existing technologies, which can significantly reduce alkali consumption and subsequent waste liquid treatment costs, while avoiding excessive etching. The added humic acid can act as a buffer to prevent drastic pH fluctuations during activation, and also as a nutrient source for subsequent microbial growth, while improving the material's ability to complex and passivate heavy metals. It should be noted that the low-concentration alkaline activation buffer should be prepared and used immediately at room temperature, and mixed with the pretreated solid waste powder within 1 hour after preparation to avoid changes in the components of the buffer due to prolonged storage, which could lead to decreased activation effect, unstable pH of the system, and affect the compatibility of subsequent microorganisms.

[0022] Furthermore, the parameters for the ultrasonic synergistic activation treatment are: ultrasonic power 200-300W, ultrasonic frequency 40kHz, treatment temperature 25-35℃, and treatment time 30-60min. The core mechanism of room-temperature ultrasonic synergistic activation lies in the fact that the cavitation effect generated by ultrasound can form local high pressure and microjets, promoting the rapid penetration of low-concentration alkaline solution into the interlayer structure of solid waste minerals, gently opening the layered lattice of inert minerals, greatly improving activation efficiency, and avoiding the damage to nutrient components caused by high-temperature activation; the ultrasonic cavitation effect can also form uniform etching on the mineral surface, accurately constructing a hierarchical porous structure, and increasing the specific surface area of ​​the carrier by 3-5 times without high-temperature calcination.

[0023] Furthermore, the in-situ pH control system is adjusted to 6.8-7.5 using dilute hydrochloric acid with a mass concentration of 0.5-1%. After activation, the pH of the system is immediately locked within the optimal neutral range for microbial growth, eliminating extreme pH stress at its source. The amount of calcium-based bentonite added is 0.3-0.8% of the total mass of the system. Calcium-based bentonite has excellent pH buffering capacity and cation exchange performance, which can maintain the stability of the system pH for a long time during the application of the material, avoiding stress to microorganisms caused by pH fluctuations in the external soil environment. At the same time, it can further enhance the material's adsorption and passivation capacity for heavy metals.

[0024] Furthermore, the solid-liquid separation is performed using a plate and frame filter press. The separated solid residue is washed with deionized water until the conductivity of the washing liquid is ≤200μS / cm. The soluble salt content in the carrier is strictly controlled to eliminate high salt osmotic pressure stress. The low-temperature drying is performed using a hot air circulating oven at a drying temperature of 40-45℃ until the moisture content is ≤12%. Low-temperature drying avoids thermal shock after subsequent microbial inoculation while preserving the porous structure of the carrier.

[0025] Furthermore, the prepared pre-activated solid waste carrier has a precise hierarchical pore structure: macropores of 10-50 μm account for ≥40%, providing exclusive colonization sites for microbial cells, forming a stable microenvironment, and protecting microorganisms from external environmental impacts; mesopores of 2-50 nm account for ≥35%, used for pollutant adsorption and nutrient storage, realizing the functional zoning of "microbial colonization" and "pollutant adsorption", and completely solving the problem of unreasonable pore structure in existing technologies.

[0026] Step 3: In-situ directional domestication-biological secondary activation integrated treatment: Using the pre-activated solid waste carrier as the sole mineral nutrient source, a directional domestication culture medium is prepared. The pre-set composite functional bacterial strain seed liquid is inoculated into the domestication culture medium for continuous subculturing and directional domestication. Simultaneously, the environmental adaptability domestication of the composite functional bacterial strain and the biological secondary activation of the pre-activated solid waste carrier are completed, resulting in a mixed system of domesticated composite bacterial liquid and biologically activated solid waste suspension. The mixed system is allowed to stand to complete the in-situ specific loading and colonization of the strains. After solid-liquid separation, a wet-based composite carrier is obtained.

[0027] Specifically, step three is the core inventive point of this invention, completely breaking the technical bias of "modification first, loading later" in existing technologies. It combines "secondary activation of solid waste" with "directed domestication and in-situ loading of strains," making the modification process a microbial adaptation process, thus fundamentally resolving the contradiction between activation modification and microbial adaptability. In this step, the metabolic products (organic acids, extracellular polymers, etc.) of the composite functional bacterial system are the sole driving force for the secondary activation of solid waste. The bioactivation process is the process of strains undergoing directed adaptation and domestication to the carrier environment. The surviving strains are dominant strains that are fully adapted to the carrier environment, can utilize the carrier's nutrients for growth, and have extremely strong stress resistance. There are no stress problems, achieving a positive cycle of "higher activation efficiency and stronger microbial colonization ability," completely reversing the negative contradiction of existing technologies.

[0028] Furthermore, the composite functional bacterial strain consists of *Bacillus jellyoidus*, *Bacillus megaterium*, *Acinetobacter rhusiolyticus*, and *Aspergillus echinococcosis*, with a viable count ratio of 2:2:1:1 for each strain; the total viable count of the seed liquid of the composite functional bacterial strain is ≥1×10⁻⁶. 9 CFU / mL. Among them, Bacillus jellyoidis and Bacillus megaterium are silicate bacteria that can secrete a large amount of organic acids and extracellular polysaccharides. They can efficiently dissociate inert silicate minerals in coal-based solid waste to achieve secondary biological activation, and passivate heavy metal ions in the soil, activate phosphorus and potassium elements in the soil, and improve soil fertility. Acinetobacter loufi exhibits excellent tolerance to heavy metals and degradation capacity for organic pollutants, which can enhance the stress resistance and compound pollution remediation capacity of the strain. Aspergillus echinococcosis can produce a variety of extracellular enzymes, further enhancing mineral activation capacity, while forming a synergistic symbiotic relationship with other strains to improve the stability of the strain.

[0029] Furthermore, the formulation of the targeted acclimatization culture medium is as follows: 20-30 g / L pre-activated solid waste carrier powder, 5 g / L glucose, 2 g / L peptone, and 1 g / L yeast extract. The initial pH of the culture medium is 7.0-7.2, and it is used after being sterilized by autoclaving at 121°C for 20 minutes. The core design of this invention lies in using the pre-activated solid waste carrier as the sole mineral nutrient source of the culture medium. The strains must activate the mineral nutrients in the carrier through their own metabolism in order to grow and reproduce normally, thereby achieving targeted acclimatization, screening out dominant strains that are fully adapted to the carrier environment, and simultaneously completing the secondary biological activation of the carrier.

[0030] Furthermore, the inoculum size for the continuous subculturing and directional domestication is 5-8%, and the domestication culture conditions are: temperature 30-32℃, shaking speed 150-180 rpm, continuous subculturing for 3-5 generations, with each generation having a culture cycle of 24 hours, and fresh directional domestication culture medium being replaced after each generation. The final domesticated compound bacterial solution has a total viable count ≥5×10⁻⁶. 9 CFU / mL. Continuous subculturing and domestication can further enhance the adaptability of the strain to the vector environment, improve the strain's stress resistance and mineral activation ability. Each subculturing process is a targeted screening of the strain and further biological activation of the vector, achieving complete synchronization of domestication and activation.

[0031] Furthermore, the conditions for in-situ specific loading and colonization are as follows: the mixture is stirred at a low speed of 50-80 rpm for 10-15 minutes to ensure uniformity, and then allowed to stand for 2-4 hours. This allows the acclimatized strain to specifically adsorb onto the pores of the metabolically activated carrier through its own secreted extracellular polymers (EPS), thus completing the in-situ loading. Unlike the non-specific physical adsorption of existing technologies, the strains of this invention specifically adsorb onto the metabolically activated carrier. The binding force between the strains and the carrier is extremely strong, making them difficult to detach. At the same time, the pore structure of the carrier and the nutrient environment are perfectly adapted to the growth requirements of the strains, resulting in an initial colonization rate of ≥65%, which is far higher than the initial colonization rate of <25% in existing technologies.

[0032] Furthermore, solid-liquid separation was performed using a low-speed centrifuge at 1000-1500 rpm to avoid damage to the bacterial cells caused by high-speed centrifugation. The resulting wet-based composite carrier had a water content of 40-50% and a viable count of ≥2×10⁻⁶. 8 CFU / g (dry basis).

[0033] Step 4: Microhabitat enhancement and low-temperature binder-free molding: Slow-release nutrients and low-temperature protectants are added to the wet-based composite carrier. The carbon-nitrogen ratio of the system is precisely controlled to the optimal range for microbial growth. After uniform mixing, the mixture is dried under low temperature vacuum, extruded and granulated without binder, and vacuum-sealed to obtain a coal-based solid waste-based microbial composite remediation material.

[0034] Specifically, the core objective of step four is to maintain microbial compatibility in the long term, construct a continuous and stable microbial microenvironment, solve the problems of microbial activity loss and decreased compatibility during the drying, molding, and storage processes of existing technologies, and at the same time take into account the formability and transportation convenience of the material for large-scale application, and avoid the damage to the material performance caused by adding binders.

[0035] Furthermore, the slow-release nutrient components are corn starch and molasses, and the cryoprotectant is trehalose; wherein the amount of corn starch added is 2-5% of the dry weight of the wet-based composite carrier, the amount of molasses added is 1-3%, and the amount of trehalose added is 0.5-1%. Corn starch and molasses serve as slow-release carbon sources, which can be slowly released during material application to provide a continuous nutrient supply for microorganisms, preventing microorganisms from becoming inactive due to nutrient depletion, and allowing for precise control of the carbon-nitrogen ratio of the system; trehalose can protect the cell membrane and protein structure of microorganisms during drying and storage, preventing cell damage during low-temperature drying and significantly reducing the loss of microbial activity.

[0036] Furthermore, the carbon-nitrogen ratio of the system is precisely controlled to 20-25:1, which is the optimal carbon-nitrogen ratio for microbial growth and reproduction. This ensures the continuous growth and metabolism of microorganisms on the carrier, achieving long-term colonization.

[0037] Furthermore, the low-temperature vacuum drying temperature is 35-40℃, the vacuum degree is -0.08~-0.1MPa, and the material is dried until the moisture content is 12-15%. Low-temperature vacuum drying can complete the drying process quickly at a lower temperature, avoiding the lethal effect of high temperature on microorganisms. At the same time, the vacuum environment can reduce the damage to the microbial cells caused by oxidation. The activity loss rate of the strain during the drying process is ≤10%, which is far lower than the level of >70% in the prior art.

[0038] Furthermore, the binder-free extrusion granulation uses a roller extrusion granulator with a granulation particle size of 2-3mm. It eliminates the need for binders such as cement and polyacrylamide, which can clog pores and inhibit microbial activity. The natural binding properties of corn starch can achieve good molding results, ensuring both the formability and transportation convenience of the material, while fully preserving the material's pore structure and microbial activity. This solves the secondary contradiction of "inability to balance formability and functionality" in existing technologies.

[0039] Furthermore, the vacuum sealing uses aluminum foil vacuum packaging bags, and after sealing, it is stored in a cool, dry place. The total effective viable bacteria count of the prepared coal-based solid waste-based microbial composite remediation material is ≥1×10⁻⁶. 8The material has the following properties: CFU / g, pH 6.5-7.5, specific surface area ≥80m² / g, heavy metal leaching content meets the limit requirements of GB5085.3-2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification", initial colonization rate ≥65%, effective viable bacteria retention rate ≥80% after 6 months of storage at room temperature, and shelf life far longer than the existing technology level of <6 months; after application, the heavy metal content in the soil meets the limit requirements of GB15618-2018 "Soil Environmental Quality - Agricultural Land Soil Pollution Risk Control Standard".

[0040] Compared with the prior art, the present invention has the following outstanding advantages:

[0041] 1. Breaking away from the existing technical bias of "high-intensity modification first, then passive loading of microorganisms", this technology integrates solid waste activation and microbial domestication, fundamentally solving the vicious cycle of "the stronger the modification, the worse the microbial activity", and improving the initial colonization rate of microorganisms and the survival rate of strains in the soil.

[0042] 2. Construct a microbial-friendly carrier microenvironment by constructing a hierarchical pore structure through gentle pre-activation, strictly controlling salinity and pH, and combining targeted domestication and screening of suitable strains to improve the initial colonization rate and long-term survival rate of microorganisms.

[0043] 3. The synergistic effect of the composite functional microbial system and the adsorption and passivation of coal-based solid waste can simultaneously achieve heavy metal passivation, soil nutrient activation and micro-ecological restoration. It is suitable for a variety of heavy metal pollution scenarios, and the remediation effect is better than existing technologies. The process has strong universality and can be adapted to different types of coal-based solid waste. The parameters of the whole process are controllable, the batch stability is good, the scale-up effect is small, and continuous industrial production can be realized. Attached Figure Description

[0044] Figure 1 This is a process flow diagram of the preparation method of the coal-based solid waste-based microbial composite remediation material of the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and comparative examples. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0047] It should be noted that the coal-based solid waste raw materials used in the following examples were all taken from typical coal-producing areas in China. Specifically, the coal gangue was taken from a coal mine in Datong, Shanxi Province; the fly ash was taken from a thermal power plant in Wuhu, Anhui Province; and the coal gasification slag was taken from a coal chemical enterprise in Yulin, Shaanxi Province. All bacterial strains used were purchased from the China General Microbiological Culture Collection Center (CGMCC), including *Bacillus spp.* CGMCC1.239, *Bacillus megaterium* CGMCC1.238, *Acinetobacter loufee* CGMCC1.3897, and *Aspergillus echinococcosis* CGMCC3.3928. All chemical reagents used were of analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd. All equipment used was conventional equipment in the field.

[0048] In the following examples and comparative examples, the detection methods for relevant performance indicators are as follows:

[0049] Effective viable bacteria count: determined using the plate count method in GB20287-2006 "Agricultural Microbial Agents";

[0050] Specific surface area and pore structure: determined by nitrogen adsorption-desorption method using a specific surface area and pore size analyzer;

[0051] Heavy metal leaching amount: determined according to HJ / T299-2007 "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method", and heavy metal concentration was detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0052] Strain survival rate: The material was inoculated into liquid culture medium and cultured. The number of viable bacteria was measured at different time points, and the survival rate was calculated.

[0053] Initial colonization rate: determined using the carrier elution counting method. The specific steps are as follows: Take 10g of wet-based composite carrier (or finished material), add 90mL of sterile physiological saline, place in a shaker at 180rpm and 30℃ for 30min to fully elute the bacterial strains colonizing the pores of the carrier, and determine the number of viable bacteria in the eluent (i.e., the number of viable bacteria colonizing the carrier) using the plate counting method. The calculation method is: Initial colonization rate = (number of viable bacteria colonizing the carrier / number of viable bacteria initially loaded on the carrier) × 100%;

[0054] Soil heavy metal passivation rate: The material was added to the composite polluted soil at a dosage of 2% (Cd content 2.3 mg / kg, Pb content 450 mg / kg, Cu content 80 mg / kg, Zn content 200 mg / kg). After 30 days of cultivation, the content of available heavy metals in the soil was determined by DTPA extraction method, and the passivation rate was calculated.

[0055] Stability at room temperature: The material was stored at 25℃ in a cool, dry place for 6 months, and the number of viable bacteria was determined and the viable bacteria retention rate was calculated.

[0056] Comprehensive energy consumption: The energy consumption corresponding to the electricity consumption and reagent consumption of each process (pretreatment, activation, acclimatization, drying, molding) is statistically analyzed. Based on Example 1 (100%), the relative comprehensive energy consumption of each experimental group is calculated.

[0057] Raw material cost: The consumption of raw materials (solid waste, reagents, nutrients, etc.) for each process was statistically analyzed. Based on Example 1 (100%), the relative raw material cost of each experimental group was calculated.

[0058] Example 1

[0059] See Figure 1 This embodiment provides a method for preparing a coal-based solid waste-based microbial composite remediation material, using coal gangue as the main raw material. The specific steps are as follows:

[0060] Step 1: Low-damage pretreatment of coal-based solid waste: Coal gangue raw material from a coal mine in Datong, Shanxi Province was selected, air-dried naturally until the moisture content was ≤15%, coarsely crushed using a jaw crusher, finely ground using a ball mill, and passed through a 100-mesh standard sieve; a wet magnetic separator was used for magnetic separation to remove impurities, with a magnetic field strength of 1200 Gs; the magnetically separated coal gangue powder was washed three times with deionized water, stirring for 15 minutes each time, and then separated by plate and frame filter press until the conductivity of the washing liquid was ≤300 μS / cm; the washed coal gangue powder was placed in a 70℃ hot air circulating oven and dried until the moisture content was ≤10%, obtaining pretreated coal gangue powder.

[0061] Step Two: Low-Concentration Alkali-Ultrasound Synergistic Mild Pre-Activation: Prepare a 2% sodium hydroxide solution and add 0.8% humic acid (by mass of the total solution) to it, stirring until homogeneous to obtain an activation buffer. Mix the pretreated coal gangue powder with the activation buffer at a liquid-to-solid ratio of 1.8:1 (mL / g) and stir until homogeneous. Place the mixture in an ultrasonic device and sonicate for 45 minutes at 250W, 40kHz, and 30℃. After ultrasonic treatment, apply 0.8% dilute hydrochloric acid in situ. Adjust the pH of the system to 7.0-7.2, add 0.5% calcium-based bentonite by mass of the total system, and stir evenly; use a plate and frame filter press for solid-liquid separation, wash the solid residue with deionized water until the conductivity of the washing liquid is ≤200μS / cm; place the solid residue in a 42℃ hot air circulating oven and dry it until the moisture content is ≤12% to obtain a pre-activated coal gangue carrier. The specific surface area is 72.3m² / g, of which 10-50μm macropores account for 42.6% and 2-50nm mesopores account for 37.2%.

[0062] Step 3: In-situ directional domestication - integrated biological secondary activation treatment:

[0063] Preparation of S1 composite functional bacterial strain seed culture: *Bacillus subtilis*, *Bacillus megaterium*, *Acinetobacter rhusiolyticus*, and *Aspergillus echinococcosis* were activated and cultured separately to prepare single-strain cultures. These cultures were then mixed at a viable cell ratio of 2:2:1:1 to obtain a total viable cell count of 1.2 × 10⁻⁶. 9 CFU / mL compound functional bacterial seed culture;

[0064] S2 directional acclimatization culture medium preparation: Using pre-activated coal gangue carrier powder as the sole mineral nutrient source, the culture medium is prepared with the following formula: 25 g / L pre-activated coal gangue carrier powder, 5 g / L glucose, 2 g / L peptone, and 1 g / L yeast extract. The initial pH is adjusted to 7.0-7.2, and the medium is then autoclaved at 121℃ for 20 minutes before use.

[0065] S3 Continuous Subculturing and Directed Acclimation: The seed culture of the compound functional bacterial strain was inoculated into the directed acclimation medium at a 6% inoculum and cultured with shaking at 31℃ and 160 rpm for 24 hours to obtain the first-generation acclimation bacterial culture. The first-generation acclimation bacterial culture was then inoculated into fresh directed acclimation medium at a 6% inoculum and cultured under the same conditions for 24 hours to obtain the second-generation acclimation bacterial culture. This process was repeated for four generations to obtain the final acclimated compound bacterial culture, which, upon testing, showed a total viable count of 6.8 × 10⁻⁶. 9 CFU / mL;

[0066] S4 in-situ specific colonization: The acclimatized mixture was stirred at 60 rpm for 12 min, and after thorough mixing, it was allowed to stand for 3 h, allowing the strains to specifically adsorb onto the pores of the bioactivated coal gangue carrier via their own EPS. Solid-liquid separation was performed using a centrifuge at 1200 rpm to obtain a wet-based composite carrier. Testing showed that its moisture content was 45%, and the effective viable count on a dry basis was 2.7 × 10⁻⁶. 8 CFU / g, initial colonization rate 75.6%.

[0067] Step 4: Microhabitat Enhancement and Low-Temperature Adhesive-Free Molding: Add 3% corn starch, 2% molasses, and 0.8% trehalose to the wet-based composite carrier by dry weight, stir evenly, and precisely control the carbon-nitrogen ratio of the system to 22:1; place the mixture in a vacuum drying oven at 38℃ and a vacuum degree of -0.09MPa, and dry it to a moisture content of 13%; granulate it using a roller extrusion granulator, controlling the particle size to 2-3mm; vacuum seal it using aluminum foil vacuum packaging bags to obtain the finished coal-based solid waste-based microbial composite remediation material.

[0068] The performance indicators of the finished product prepared in this embodiment were tested and found to be as follows: the total number of effective viable bacteria was 1.8 × 10⁻⁶. 8 The material has a CFU / g concentration, a pH of 7.1, and a specific surface area of ​​86.5 m² / g. The leaching amounts of heavy metals such as Cd, Pb, Cr, and As are all far below the limits specified in GB5085.3-2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification". The initial colonization rate is 75.6%. After 6 months of storage at room temperature, the effective viable bacteria retention rate is 86.2%. The survival rate of the strain in the soil after 3 months is 58.7%. The passivation rates for available Cd, Pb, Cu, and Zn in the soil are 92.3%, 94.6%, 91.1%, and 90.5%, respectively. After application, the heavy metal content in the soil meets the limits specified in GB15618-2018 "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control". The relative comprehensive energy consumption is 100%, and the relative raw material cost is 100%.

[0069] Example 2

[0070] This embodiment provides a method for preparing a coal-based solid waste-based microbial composite remediation material, using fly ash as the main raw material. The specific steps are as follows:

[0071] Step 1: Low-damage pretreatment of coal-based solid waste: Fly ash raw material from a thermal power plant in Wuhu, Anhui Province was selected, air-dried naturally until the moisture content was ≤15%, and passed through a 100-mesh standard sieve to remove large particulate impurities; a wet magnetic separator was used for magnetic separation to remove impurities, with a magnetic field strength of 1000 Gs; the magnetically separated fly ash was washed twice with deionized water, with stirring for 10 minutes each time, and solid-liquid separation was performed by plate and frame filter press until the conductivity of the washing liquid was ≤300 μS / cm; the washed fly ash was placed in a 60℃ hot air circulating oven and dried until the moisture content was ≤10%, thus obtaining pretreated fly ash.

[0072] Step 2: Low-concentration alkali-ultrasound synergistic mild pre-activation: Prepare a 1% sodium hydroxide solution and add 0.5% humic acid (by mass of the total solution) to it, stirring until homogeneous to obtain an activation buffer. Mix the pretreated fly ash with the activation buffer at a liquid-to-solid ratio of 1.5:1 (mL / g) and stir until homogeneous. Place the mixture in an ultrasonic device and sonicate for 60 minutes at 200W, 40kHz, and 25℃. After ultrasonic treatment, apply 0.5% dilute hydrochloric acid in situ. Adjust the pH of the system to 6.8-7.0, add 0.3% calcium-based bentonite by mass of the total system, and stir evenly; use a plate and frame filter press for solid-liquid separation, wash the solid residue with deionized water until the conductivity of the washing liquid is ≤200μS / cm; place the solid residue in a 40℃ hot air circulating oven and dry it until the moisture content is ≤12% to obtain a pre-activated fly ash carrier. The specific surface area is 68.5m² / g, of which 10-50μm macropores account for 41.2% and 2-50nm mesopores account for 36.5%.

[0073] Step 3: In-situ directional domestication - integrated biological secondary activation treatment:

[0074] Preparation of S1 composite functional bacterial strain seed culture: Same as in Example 1, yielding a total viable count of 1.1 × 10⁻⁶. 9 CFU / mL compound functional bacterial seed culture;

[0075] S2 directional acclimatization culture medium preparation: Using pre-activated fly ash carrier powder as the sole mineral nutrient source, the culture medium is prepared with the following formula: 20 g / L pre-activated fly ash carrier powder, 5 g / L glucose, 2 g / L peptone, and 1 g / L yeast extract. The initial pH is adjusted to 7.0-7.2, and the medium is then autoclaved at 121℃ for 20 minutes before use.

[0076] S3 Continuous Subculturing and Directed Acclimation: The seed culture of the compound functional bacterial strain was inoculated into the directed acclimation medium at an inoculation rate of 5%, and cultured with shaking at 30℃ and 150 rpm for 24 h. This process was repeated for 3 generations to obtain the acclimated compound bacterial culture. The total viable count was found to be 5.5 × 10⁻⁶. 9 CFU / mL;

[0077] S4 in-situ specific loading colonization: The acclimatized mixture was stirred at 50 rpm for 10 min, and after thorough mixing, it was allowed to stand for 2 h. Solid-liquid separation was then performed using a centrifuge at 1000 rpm to obtain the wet-based composite carrier. Testing showed that its moisture content was 40%, and the effective viable count on the dry basis was 2.2 × 10⁻⁶. 8 CFU / g, initial colonization rate 68.3%.

[0078] Step 4: Microhabitat Enhancement and Low-Temperature Adhesive-Free Molding: Add 2% corn starch, 1% molasses, and 0.5% trehalose to the wet-based composite carrier by dry weight, stir evenly, and precisely control the carbon-nitrogen ratio of the system to 20:1; place the mixture in a vacuum drying oven at 35℃ and a vacuum degree of -0.08MPa, and dry it to a moisture content of 12%; granulate it using a roller extrusion granulator, controlling the particle size to 2-3mm; vacuum seal it using aluminum foil vacuum packaging bags to obtain the finished coal-based solid waste-based microbial composite remediation material.

[0079] The performance indicators of the finished product prepared in this embodiment were tested and found to be as follows: the total number of effective viable bacteria was 1.5 × 10⁻⁶. 8 The material has a concentration of CFU / g, a pH of 6.9, a specific surface area of ​​81.2 m² / g, and heavy metal leaching levels that meet the limits of GB5085.3-2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification". The initial colonization rate is 68.3%. After 6 months of storage at room temperature, the effective viable bacteria retention rate is 82.5%. The survival rate of the strain in the soil after 3 months is 53.4%. The passivation rate for available Cd in the soil is 90.1%, for available Pb it is 92.7%, for available Cu it is 89.8%, and for available Zn it is 89.2%. After application, the heavy metal content in the soil meets the limits of GB15618-2018 "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control". The relative comprehensive energy consumption is 97%, and the relative raw material cost is 95%.

[0080] Example 3

[0081] This embodiment provides a method for preparing a coal-based solid waste-based microbial composite remediation material, using coal gasification slag as the main raw material. The specific steps are as follows:

[0082] Step 1: Low-damage pretreatment of coal-based solid waste: Coal gasification slag raw material from a coal chemical enterprise in Yulin, Shaanxi Province was selected, naturally air-dried until the moisture content was ≤15%, crushed, and passed through a 120-mesh standard sieve; a wet magnetic separator was used for magnetic separation to remove impurities, with a magnetic field strength of 1500 Gs; the gasification slag powder after magnetic separation was washed three times with deionized water, stirring for 15 minutes each time, and then separated by plate and frame filter press until the conductivity of the washing liquid was ≤300 μS / cm; the washed gasification slag powder was placed in an 80℃ hot air circulating oven and dried until the moisture content was ≤10%, thus obtaining pretreated gasification slag powder.

[0083] Step Two: Low-Concentration Alkali-Ultrasound Synergistic Mild Pre-Activation: Prepare a 3% sodium hydroxide solution and add 1% humic acid (by mass of the total solution) to it, stirring until homogeneous to obtain an activation buffer. Mix the pretreated gasification slag powder with the activation buffer at a liquid-to-solid ratio of 2:1 (mL / g) and stir until homogeneous. Place the mixture in an ultrasonic device and sonicate for 30 minutes at 300W, 40kHz, and 35℃. After ultrasonic treatment, use 1% dilute hydrochloric acid in situ to regulate the mixture. Adjust the pH to 7.2-7.5, add 0.8% calcium-based bentonite by mass of the total system, and stir evenly; use a plate and frame filter press for solid-liquid separation, wash the solid residue with deionized water until the conductivity of the washing liquid is ≤200μS / cm; place the solid residue in a 45℃ hot air circulating oven and dry it until the moisture content is ≤12% to obtain a pre-activated gasification slag carrier. The specific surface area is 75.8m² / g, of which 10-50μm macropores account for 43.5% and 2-50nm mesopores account for 38.1%.

[0084] Step 3: In-situ directional domestication - integrated biological secondary activation treatment:

[0085] Preparation of S1 composite functional bacterial strain seed culture: Same as in Example 1, yielding a total viable count of 1.3 × 10⁻⁶. 9 CFU / mL compound functional bacterial seed culture;

[0086] S2 directional acclimatization culture medium preparation: Using pre-activated gasification slag carrier powder as the sole mineral nutrient source, the culture medium is prepared with the following formula: 30 g / L pre-activated gasification slag carrier powder, 5 g / L glucose, 2 g / L peptone, and 1 g / L yeast extract. The initial pH is adjusted to 7.0-7.2, and the medium is then autoclaved at 121℃ for 20 minutes before use.

[0087] S3 Continuous Subculturing and Directed Acclimation: The seed culture of the compound functional bacterial strain was inoculated into the directed acclimation medium at an inoculation rate of 8%, and cultured with shaking at 32℃ and 180 rpm for 24 h. This process was repeated for 5 generations to obtain the acclimated compound bacterial culture. The total viable count was measured to be 7.2 × 10⁻⁶. 9 CFU / mL;

[0088] S4 in-situ specific colonization: The acclimatized mixture was stirred at 80 rpm for 15 min, and after thorough mixing, it was allowed to stand for 4 h, allowing the strains to specifically adsorb onto the pores of the bioactivated gasification slag carrier via their own EPS. Solid-liquid separation was performed using a centrifuge at 1500 rpm to obtain a wet-based composite carrier. Testing showed that its moisture content was 50%, and the effective viable count on a dry basis was 2.9 × 10⁻⁶. 8 CFU / g, initial colonization rate 78.9%.

[0089] Step 4: Microenvironment enhancement and low-temperature binder-free molding: Add 5% corn starch, 3% molasses, and 1% trehalose by dry weight to the wet-based composite carrier, stir evenly, and precisely control the carbon-nitrogen ratio of the system to 25:1; place the mixture in a vacuum drying oven at 40℃ and a vacuum degree of -0.1MPa, and dry it to a moisture content of 15%; granulate it using a roller extrusion granulator, and control the particle size to 2-3mm; vacuum seal it using aluminum foil vacuum packaging bags to obtain the finished coal-based solid waste-based microbial composite remediation material.

[0090] The performance indicators of the finished product prepared in this embodiment were tested and found to be as follows: the total number of effective viable bacteria was 2.1 × 10⁻⁶. 8 The material has a CFU / g concentration, a pH of 7.3, and a specific surface area of ​​90.8 m² / g. The leaching amounts of heavy metals such as Cd, Pb, Cr, and As are all far below the limits specified in GB5085.3-2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification". The initial colonization rate is 78.9%. After 6 months of storage at room temperature, the effective viable bacteria retention rate is 88.7%. The survival rate of the strains in the soil after 3 months is 62.3%. The passivation rates for available Cd, Pb, Cu, and Zn in the soil are 93.8%, 95.2%, 91.5%, and 90.8%, respectively. After application, the heavy metal content in the soil meets the limits specified in GB15618-2018 "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control". The relative comprehensive energy consumption is 105%, and the relative raw material cost is 102%.

[0091] Example 4

[0092] This embodiment provides a method for preparing a coal-based solid waste-based microbial composite remediation material, using washed coal slime as the main raw material. The specific steps are as follows:

[0093] Step 1: Low-damage pretreatment of coal-based solid waste: Coal sludge raw material from a coal mine in Jincheng, Shanxi Province was selected, air-dried to a moisture content of ≤15%, coarsely crushed using a jaw crusher, finely ground using a ball mill, and passed through a 100-mesh standard sieve; a wet magnetic separator was used for magnetic separation to remove impurities, with a magnetic field strength of 1300 Gs; the magnetically separated coal sludge powder was washed three times with deionized water, stirring for 12 minutes each time, and then separated by plate and frame filter press until the conductivity of the washing liquid was ≤300 μS / cm; the washed coal sludge powder was placed in a 75℃ hot air circulating oven and dried to a moisture content of ≤10% to obtain pretreated coal sludge powder.

[0094] Step 2: Low-concentration alkali-ultrasound synergistic mild pre-activation: Prepare a 2% sodium hydroxide solution and add 0.7% humic acid (by mass of the total solution) to it, stirring until homogeneous to obtain an activation buffer. Mix the pretreated coal slurry powder with the activation buffer at a liquid-to-solid ratio of 1.7:1 (mL / g) and stir until homogeneous. Place the mixture in an ultrasonic device and sonicate for 40 min at 240 W, 40 kHz, and 32 °C. After ultrasonic treatment, apply 0.7% dilute hydrochloric acid in situ. Adjust the pH of the system to 7.0-7.2, add 0.6% calcium-based bentonite by mass of the system, and stir evenly; use a plate and frame filter press for solid-liquid separation, and wash the solid residue with deionized water until the conductivity of the washing liquid is ≤200μS / cm; place the solid residue in a 43℃ hot air circulating oven and dry it until the moisture content is ≤12% to obtain a pre-activated coal slime carrier. The specific surface area is 70.5m² / g, of which 10-50μm macropores account for 42.1% and 2-50nm mesopores account for 36.8%.

[0095] Step 3: In-situ directional domestication - integrated biological secondary activation treatment:

[0096] Preparation of S1 composite functional bacterial strain seed culture: Same as in Example 1, yielding a total viable count of 1.2 × 10⁻⁶. 9 CFU / mL compound functional bacterial seed culture;

[0097] S2 directional acclimatization culture medium preparation: Using pre-activated coal slurry carrier powder as the sole mineral nutrient source, the culture medium was prepared with the following formula: 24 g / L pre-activated coal slurry carrier powder, 5 g / L glucose, 2 g / L peptone, and 1 g / L yeast extract. The initial pH was adjusted to 7.0-7.2, and the medium was autoclaved at 121℃ for 20 minutes before use.

[0098] S3 Continuous Subculturing and Directed Acclimation: The seed culture of the compound functional bacterial strain was inoculated into the directed acclimation medium at an inoculation rate of 6%, and cultured with shaking at 31℃ and 165 rpm for 24 h. This process was repeated for 4 generations to obtain the acclimated compound bacterial culture. The total viable count was found to be 6.5 × 10⁻⁶. 9 CFU / mL;

[0099] S4 in-situ specific loading and colonization: The acclimatized mixture was stirred at a low speed of 65 rpm for 12 min, and after thorough mixing, it was allowed to stand for 3 h, allowing the strains to specifically adsorb onto the pores of the bioactivated coal slurry carrier via their own EPS. Solid-liquid separation was performed using a low-speed centrifuge at 1300 rpm to obtain a wet-based composite carrier. Testing showed that its moisture content was 44%, and the effective viable count on a dry basis was 2.5 × 10⁻⁶. 8 CFU / g, initial colonization rate 72.8%.

[0100] Step 4: Microhabitat Enhancement and Low-Temperature Adhesive-Free Molding: Add 3% corn starch, 2% molasses, and 0.7% trehalose to the wet-based composite carrier by dry weight, stir evenly, and precisely control the carbon-nitrogen ratio of the system to 22:1; place the mixture in a vacuum drying oven at 37℃ and a vacuum degree of -0.09MPa, and dry it to a moisture content of 13%; granulate it using a roller extrusion granulator, controlling the particle size to 2-3mm; vacuum seal it using aluminum foil vacuum packaging bags to obtain the finished coal-based solid waste-based microbial composite remediation material.

[0101] The performance indicators of the finished product prepared in this embodiment were tested and found to be as follows: the total number of effective viable bacteria was 1.6 × 10⁻⁶. 8 The material has a CFU / g concentration, a pH of 7.1, and a specific surface area of ​​85.2 m² / g. The leaching amounts of heavy metals such as Cd, Pb, Cr, and As are all significantly lower than the limits specified in GB5085.3-2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification". The initial colonization rate is 72.8%. After 6 months of storage at room temperature, the effective viable bacteria retention rate is 85.1%. The survival rate of the strain in the soil after 3 months is 56.9%. The passivation rates for available Cd, Pb, Cu, and Zn in the soil are 91.7%, 93.9%, 90.7%, and 89.9%, respectively. After application, the heavy metal content in the soil meets the limits specified in GB15618-2018 "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control". The relative comprehensive energy consumption is 99%, and the relative raw material cost is 98%.

[0102] Example 5

[0103] This embodiment provides a method for preparing a coal-based solid waste-based microbial composite remediation material, using coal gangue and fly ash (mass ratio 1:1) as mixed raw materials. The specific steps are as follows:

[0104] Step 1: Low-damage pretreatment of coal-based solid waste: Coal gangue from a coal mine in Datong, Shanxi Province, and fly ash from a thermal power plant in Wuhu, Anhui Province, were mixed at a mass ratio of 1:1 and air-dried until the moisture content was ≤15%. After coarse crushing with a jaw crusher, the mixture was finely ground with a ball mill and passed through a 100-mesh standard sieve. A wet magnetic separator was used for magnetic separation to remove impurities, with a magnetic field strength of 1250 Gs. The mixed solid waste powder after magnetic separation was washed three times with deionized water, stirring for 13 minutes each time. Solid-liquid separation was performed by plate and frame filter press until the conductivity of the washing liquid was ≤300 μS / cm. The washed mixed solid waste powder was placed in a 72℃ hot air circulating oven and dried until the moisture content was ≤10%, resulting in pretreated mixed solid waste powder.

[0105] Step Two: Low-Concentration Alkali-Ultrasound Synergistic Mild Pre-Activation: Prepare a 2% sodium hydroxide solution and add 0.8% humic acid (by mass of the total solution), stirring until homogeneous to obtain an activation buffer. Mix the pretreated mixed solid waste powder with the activation buffer at a liquid-to-solid ratio of 1.8:1 (mL / g) and stir until homogeneous. Place the mixture in an ultrasonic device and sonicate for 42 minutes at 250W, 40kHz, and 31℃. After ultrasonic treatment, apply 0.8% dilute hydrochloric acid in situ. Adjust the pH of the system to 7.0-7.2, add 0.5% calcium-based bentonite by mass of the system, and stir evenly; use a plate and frame filter press for solid-liquid separation, wash the solid residue with deionized water until the conductivity of the washing liquid is ≤200μS / cm; place the solid residue in a 42℃ hot air circulating oven and dry it until the moisture content is ≤12% to obtain a pre-activated mixed solid waste carrier. The specific surface area is 73.1m² / g, of which 10-50μm macropores account for 42.4% and 2-50nm mesopores account for 37.0%.

[0106] Step 3: In-situ directional domestication - integrated biological secondary activation treatment:

[0107] Preparation of S1 composite functional bacterial strain seed culture: Same as in Example 1, yielding a total viable count of 1.2 × 10⁻⁶. 9 CFU / mL compound functional bacterial seed culture;

[0108] S2 directional acclimatization culture medium preparation: Using pre-activated mixed solid waste carrier powder as the sole mineral nutrient source, the culture medium is prepared with the following formula: 25 g / L pre-activated mixed solid waste carrier powder, 5 g / L glucose, 2 g / L peptone, and 1 g / L yeast extract. The initial pH is adjusted to 7.0-7.2, and the medium is then autoclaved at 121℃ for 20 minutes before use.

[0109] S3 Continuous Subculturing and Directed Acclimation: The seed culture of the compound functional bacterial strain was inoculated into the directed acclimation medium at an inoculation rate of 6%, and cultured with shaking at 31℃ and 160 rpm for 24 h. This process was repeated for 4 generations to obtain the acclimated compound bacterial culture. The total viable count was measured to be 6.7 × 10⁻⁶. 9 CFU / mL;

[0110] S4 in-situ specific colonization: The acclimatized mixed system was stirred at a low speed of 60 rpm for 12 min, and after thorough mixing, it was allowed to stand for 3 h, allowing the bacterial strains to specifically adsorb onto the pores of the bioactivated mixed solid waste carrier via their own EPS. Solid-liquid separation was performed using a low-speed centrifuge at 1200 rpm to obtain a wet-based composite carrier. Testing showed that its moisture content was 45%, and the effective viable count on a dry basis was 2.6 × 10⁻⁶. 8 CFU / g, initial colonization rate 74.2%.

[0111] Step 4: Microhabitat Enhancement and Low-Temperature Adhesive-Free Molding: Add 3% corn starch, 2% molasses, and 0.8% trehalose to the wet-based composite carrier by dry weight, stir evenly, and precisely control the carbon-nitrogen ratio of the system to 22:1; place the mixture in a vacuum drying oven at 38℃ and a vacuum degree of -0.09MPa, and dry it to a moisture content of 13%; granulate it using a roller extrusion granulator, controlling the particle size to 2-3mm; vacuum seal it using aluminum foil vacuum packaging bags to obtain the finished coal-based solid waste-based microbial composite remediation material.

[0112] The performance indicators of the finished product prepared in this embodiment were tested and found to be as follows: the total number of effective viable bacteria was 1.7 × 10⁻⁶. 8 The material has a CFU / g concentration, a pH of 7.1, and a specific surface area of ​​86.1 m² / g. The leaching amounts of heavy metals such as Cd, Pb, Cr, and As are all significantly lower than the limits specified in GB5085.3-2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification". The initial colonization rate is 74.2%. After 6 months of storage at room temperature, the effective viable bacteria retention rate is 85.8%. The survival rate of the strains in the soil after 3 months is 57.8%. The passivation rates for available Cd, Pb, Cu, and Zn in the soil are 92.0%, 94.3%, 90.9%, and 90.3%, respectively. After application, the heavy metal content in the soil meets the limits specified in GB15618-2018 "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control". The relative comprehensive energy consumption is 102%, and the relative raw material cost is 101%.

[0113] Comparative Example 1

[0114] This comparative example uses existing conventional processes (high-temperature calcination + high-concentration alkali activation + pre-modification followed by microbial loading) to prepare coal-based solid waste-based microbial composite remediation materials. The specific steps are as follows:

[0115] Solid waste pretreatment: Same as step one (coal gangue raw material) in Example 1, to obtain pretreated coal gangue powder.

[0116] High-temperature calcination + high-concentration alkali activation: Pretreated coal gangue powder was calcined in a muffle furnace at 500℃ for 2 hours. After cooling to room temperature, it was mixed with a 10% sodium hydroxide solution at a liquid-to-solid ratio of 2:1 (mL / g) and activated by stirring in an 80℃ water bath for 2 hours. The pH was adjusted to 7.0-7.2 with dilute hydrochloric acid, and the solid and liquid were separated and washed with water until the conductivity was ≤200μS / cm. The mixture was then dried at 105℃ until the moisture content was ≤12% to obtain the modified coal gangue carrier.

[0117] Passive loading of microorganisms: Prepare the seed liquid of the composite functional bacterial strain in step S1 of the same step 3 of Example 1. Mix the modified coal gangue carrier and the bacterial liquid at a mass ratio of 10:1, stir and adsorb at 25°C for 1 hour, and dry at a low temperature of 38°C and vacuum degree of -0.09MPa until the water content is ≤15% to obtain the loaded bacterial carrier.

[0118] Conventional molding: 5% cement is added to the bacterial carrier as a binder, mixed evenly, and then extruded into granules (particle size 2-3mm). After low-temperature vacuum drying at 38℃ and vacuum degree -0.09MPa to a moisture content of 13%, the product is packaged to obtain the finished product.

[0119] The performance indicators of the finished product prepared in this comparative example were as follows: the total number of effective viable bacteria was 3.2 × 10⁻⁶. 7 The sample had a concentration of CFU / g, a pH of 7.2, and a specific surface area of ​​78.6 m² / g. The initial colonization rate was 22.8%. After 6 months of storage at room temperature, the retention rate of viable bacteria was 35.7%. The survival rate of the strain in soil after 3 months was 13.6%. The passivation rate of available Cd in soil was 68.5%, the passivation rate of available Pb was 70.2%, the passivation rate of available Cu was 65.3%, and the passivation rate of available Zn was 63.8%. The relative comprehensive energy consumption was 172%, and the relative raw material cost was 185%.

[0120] Comparative Example 2

[0121] This comparative example omits step one, the low-damage pretreatment step for coal-based solid waste, of the present invention. The remaining steps are completely consistent with Example 1, with the following specific adjustments:

[0122] Coal gangue raw material from a coal mine in Datong, Shanxi Province was directly selected. It was not subjected to natural air drying, magnetic separation for impurity removal, or water washing and desalination. It was only crushed through a 100-mesh standard sieve and directly used for the pre-activation treatment in step two. Steps two, three, and four are exactly the same as in Example 1.

[0123] The performance indicators of the finished product prepared in this comparative example were as follows: the total number of effective viable bacteria was 8.5 × 10⁻⁶. 7 The sample had a concentration of CFU / g, a pH of 6.8, and a specific surface area of ​​65.3 m² / g. The initial colonization rate was 42.1%. After 6 months of storage at room temperature, the retention rate of viable bacteria was 68.3%. The survival rate of the strain in soil after 3 months was 32.5%. The passivation rate of available Cd in the soil was 78.6%, and the passivation rate of available Pb was 80.1%. The relative comprehensive energy consumption was 98%, and the relative raw material cost was 96%.

[0124] Comparative Example 3

[0125] This comparative example omits step two of the invention: the low-concentration alkali-ultrasound synergistic mild pre-activation step. The remaining steps are completely consistent with Example 1, with the following specific adjustments:

[0126] After step one is completed, the pretreated coal gangue powder is used directly as a carrier, skipping the pre-activation treatment in step two, and directly proceeding to step three, in-situ directional domestication-biological secondary activation integrated treatment; steps three and four are exactly the same as in Example 1.

[0127] The performance indicators of the finished product prepared in this comparative example were as follows: the total number of effective viable bacteria was 7.2 × 10⁻⁶. 7 The sample had a concentration of CFU / g, a pH of 7.0, and a specific surface area of ​​48.9 m² / g. The initial colonization rate was 38.7%. After 6 months of storage at room temperature, the retention rate of viable bacteria was 65.8%. The survival rate of the strain in soil after 3 months was 28.9%. The passivation rate of available Cd in soil was 72.3%, and the passivation rate of available Pb was 75.6%. The relative comprehensive energy consumption was 82%, and the relative raw material cost was 98%.

[0128] Comparative Example 4

[0129] This comparative example omits the integrated in-situ directional domestication-biological secondary activation treatment step three of the present invention. The remaining steps are completely consistent with Example 1, with the following specific adjustments:

[0130] After step two is completed, a pre-activated coal gangue carrier is obtained; the composite functional bacterial seed liquid prepared in Example 1 is directly mixed with the pre-activated coal gangue carrier at a mass ratio of 10:1, stirred and adsorbed at 25°C for 1 hour to complete passive loading (no directional domestication, no secondary biological activation), and then proceeds directly to step four; step four is exactly the same as in Example 1.

[0131] The performance indicators of the finished product prepared in this comparative example were as follows: the total number of effective viable bacteria was 5.8 × 10⁻⁶. 7 The sample had a concentration of CFU / g, a pH of 7.1, and a specific surface area of ​​70.2 m² / g. The initial colonization rate was 25.3%. After 6 months of storage at room temperature, the retention rate of viable bacteria was 42.6%. The survival rate of the strain in soil after 3 months was 15.8%. The passivation rates for available Cd, Pb, Cu, and Zn in soil were 75.1%, 78.3%, 72.6%, and 71.4%, respectively. The relative comprehensive energy consumption was 88%, and the relative raw material cost was 97%.

[0132] Comparative Example 5

[0133] This comparative example omits step four, the microenvironment enhancement and low-temperature adhesive-free molding step, of the present invention. The remaining steps are completely consistent with Example 1, with the following specific adjustments:

[0134] After step three is completed, a wet-based composite carrier is obtained; without adding slow-release nutrients and low-temperature protectants, it is directly dried at 105°C to a moisture content of 13%, 5% cement is added as a binder for extrusion granulation, and then naturally dried and packaged; the remaining steps are exactly the same as in Example 1.

[0135] The performance indicators of the finished product prepared in this comparative example were as follows: the total number of effective viable bacteria was 4.3 × 10⁻⁶. 7 The sample had a concentration of CFU / g, a pH of 7.1, and a specific surface area of ​​72.8 m² / g. The initial colonization rate was 30.5%. After 6 months of storage at room temperature, the retention rate of viable bacteria was 38.9%. The survival rate of the strain in soil after 3 months was 18.2%. The passivation rate of available Cd in soil was 76.8%, the passivation rate of available Pb was 79.5%, the passivation rate of available Cu was 74.2%, and the passivation rate of available Zn was 73.1%. The relative comprehensive energy consumption was 95%, and the relative raw material cost was 108%.

[0136] Compared with the prior art Comparative Example 1, the initial planting rate of Examples 1-3 of the present invention is increased by 2.3-3.4 times (75.6%-78.9% vs 22.8%), the survival rate of strains in the soil for 3 months is increased by 4.3-4.6 times (53.4%-62.3% vs 13.6%), the overall energy consumption is reduced by 41.9%-47.1% (100%-105% vs 172%), the raw material cost is reduced by 45.9%-49.7% (95%-102% vs 185%), and the heavy metal passivation rate is increased by 19.8%-25.3%, proving the invention's superiority. This invention resolves the core contradiction of existing technologies where "the stronger the modification, the worse the microbial activity." The quantitative improvement effect is supported by clear experimental data. Compared with the single-variable control examples (2-5), the absence of any one of the core steps of this invention significantly reduced the effective viable bacteria count, initial colonization rate, strain survival rate, and heavy metal passivation rate of the finished product (reduction range of 15%-60%). Among them, the performance decline was most significant in control example 4, which lacked step three, in-situ directional domestication-biological secondary activation. Compared with Example 1, the initial colonization rate decreased by 66.8%, and the strain survival rate decreased by 73.1%.

[0137] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a coal-based solid waste-based microbial composite remediation material, characterized in that: Step 1: Select coal-based solid waste raw materials, and process them through natural air drying, crushing and screening, magnetic separation for impurity removal, water washing and desalination, and low-temperature drying to obtain pretreated solid waste powder; Step 2: Prepare a low-concentration alkaline activation buffer solution with a mass concentration of 1-3% sodium hydroxide. Add 0.5-1% humic acid to the buffer solution. Mix the pretreated solid waste powder with the activation buffer solution at a liquid-to-solid ratio of 1.5-2:1 mL / g. Perform ultrasonic synergistic activation treatment at room temperature with an ultrasonic power of 200-300W, a frequency of 40kHz, and a treatment time of 30-60min. After activation, adjust the pH of the system to 6.8-7.5 in situ. Add 0.3-0.8% calcium-based bentonite to construct a long-lasting pH buffer system. After solid-liquid separation, water washing, and low-temperature drying, the pre-activated solid waste carrier is obtained. Step 3: Using the pre-activated solid waste carrier as the sole mineral nutrient source, a directional acclimatization culture medium is prepared. The seed liquid of the composite functional bacterial strain is inoculated into the acclimatization culture medium and continuously passaged for directional acclimatization. Simultaneously, the environmental adaptability acclimatization of the composite functional bacterial strain and the secondary biological activation of the pre-activated solid waste carrier are completed, resulting in a mixed system of acclimatized composite bacterial liquid and biologically activated solid waste suspension. The mixed system is allowed to stand to complete the in-situ specific loading and colonization of the strains. After solid-liquid separation, a wet-based composite carrier is obtained. The composite functional bacterial strain is composed of Bacillus subtilis, Bacillus megaterium, Acinetobacter rofibrinolyticus, and Aspergillus echinosporum in a viable cell ratio of 2:2:1:

1. Step 4: Add slow-release nutrients and cryoprotectant to the wet-based composite carrier, precisely adjust the carbon-nitrogen ratio of the system to 20-25:1, mix evenly, and then perform low-temperature vacuum drying, binder-free extrusion granulation, and vacuum encapsulation to obtain coal-based solid waste-based microbial composite remediation material.

2. The preparation method of a coal-based solid waste-based microbial composite remediation material according to claim 1, characterized in that: In step one, the coal-based solid waste raw material is any one or a mixture of two or more of the following in any proportion: coal gangue, fly ash, coal gasification slag, and coal washing slime; the crushing and screening specifically involves crushing the air-dried coal-based solid waste and passing it through an 80-120 mesh standard sieve; the magnetic separation for impurity removal uses a wet magnetic separator with a magnetic field strength of 1000-1500 Gs; the water washing and desalination involves washing the screened solid waste powder 2-3 times with deionized water, stirring for 10-15 minutes each time, until the solid-liquid separation is achieved and the conductivity of the washing liquid is ≤300 μS / cm; the low-temperature drying temperature is 60-80℃, and the drying is carried out until the moisture content of the pretreated solid waste powder is ≤10%.

3. The preparation method of a coal-based solid waste-based microbial composite remediation material according to claim 1, characterized in that: In step two, the low-concentration alkaline activation buffer is a sodium hydroxide solution with a mass concentration of 1-3%, and 0.5-1% humic acid is added to the activation buffer. The liquid-to-solid ratio of the pretreated solid waste powder to the activation buffer is 1.5-2:1, in mL / g. The low-concentration alkaline activation buffer is prepared fresh at room temperature and mixed with the pretreated solid waste powder within 1 hour after preparation.

4. The preparation method of a coal-based solid waste-based microbial composite remediation material according to claim 1, characterized in that: In step two, the parameters for the ultrasonic synergistic activation treatment are as follows: ultrasonic power 200-300W, ultrasonic frequency 40kHz, treatment temperature 25-35℃, and treatment time 30-60min; the pH of the in-situ controlled system is adjusted to 6.8-7.5 using 0.5-1% dilute hydrochloric acid; the amount of calcium-based bentonite added is 0.3-0.8% of the total mass of the system; the water washing is performed until the conductivity of the solid residue washing liquid is ≤200μS / cm; the low-temperature drying temperature is 40-45℃, and the drying is performed until the moisture content is ≤12%.

5. The preparation method of a coal-based solid waste-based microbial composite remediation material according to claim 1, characterized in that: In step three, the composite functional bacterial strain consists of *Bacillus jellyoidus*, *Bacillus megaterium*, *Acinetobacter rouxii*, and *Aspergillus echinococcosis*, with a viable count ratio of 2:2:1:1 for each strain; the total viable count of the seed liquid of the composite functional bacterial strain is ≥1×10⁻⁶. 9 CFU / mL.

6. The preparation method of a coal-based solid waste-based microbial composite remediation material according to claim 1, characterized in that: In step three, the formulation of the directional acclimatization culture medium is as follows: 20-30 g / L of pre-activated solid waste carrier powder, 5 g / L of glucose, 2 g / L of peptone, and 1 g / L of yeast extract. The initial pH of the culture medium is 7.0-7.2, and it is used after being sterilized by high-pressure steam at 121°C for 20 minutes.

7. The preparation method of a coal-based solid waste-based microbial composite remediation material according to claim 1, characterized in that: In step three, the inoculum size for continuous subculturing and directional acclimatization is 5-8%, and the acclimatization culture conditions are: temperature 30-32℃, shaking speed 150-180 rpm, continuous subculturing for 3-5 generations, with each generation having a culture cycle of 24 hours, and fresh directional acclimatization culture medium being replaced after each generation. The final acclimatized compound bacterial solution has a total viable count ≥5×10⁻⁶. 9 CFU / mL.

8. The preparation method of a coal-based solid waste-based microbial composite remediation material according to claim 1, characterized in that: In step three, the conditions for in-situ specific colonization are as follows: low-speed stirring for 10-15 minutes to homogenize the mixture, standing for 2-4 hours, with a stirring speed of 50-80 rpm; the moisture content of the wet-based composite carrier is 40-50%, and the effective viable count of the loaded carrier is ≥2×10⁻⁶. 8 CFU / g (dry basis), initial planting rate ≥65%.

9. The preparation method of a coal-based solid waste-based microbial composite remediation material according to claim 1, characterized in that: In step four, the slow-release nutrient components are corn starch and molasses, and the cryoprotectant is trehalose; The amount of corn starch added is 2-5% of the dry weight of the wet-based composite carrier, the amount of molasses added is 1-3%, and the amount of trehalose added is 0.5-1%; the carbon-nitrogen ratio of the system is precisely controlled to 20-25:

1.

10. The method for preparing a coal-based solid waste-based microbial composite remediation material according to claim 1, characterized in that: In step four, the low-temperature vacuum drying temperature is 35-40℃, and the material is dried until the moisture content is 12-15%; the binder-free extrusion granulation uses a double-roller extrusion granulator, and the granulation particle size is 2-3mm; the total effective viable bacteria count of the prepared coal-based solid waste-based microbial composite remediation material is ≥1×10⁻⁶. 8 CFU / g, pH 6.5-7.5, specific surface area ≥80m² / g.

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