A method for promoting the development of water-stable macroaggregates in red mud

Abstract

The present invention relates to a method for promoting the development of water-stable macroaggregates in red mud. The method comprises separating hyalophora and hyalophora from algae crusts on the surface of a red mud pile, purifying, propagating, and filtering the hyalophora propagation concentrate and hyalophora propagation concentrate, mixing the two in equal volumes to obtain an algae-promoting liquid, and then spraying the liquid evenly on the surface of the red mud pile. When a blue-green algae crust grows on the surface of the red mud pile and the total nitrogen content is ≥0.1% and the total organic carbon content is ≥1.0%, the surface red mud is plowed for the first time, and then a bacterial-promoting liquid and a fungal-promoting liquid are sprayed and plowed for the second time. The red mud is regularly sprinkled with water to moisten the red mud. The present invention utilizes a combined algae, fungi, and bacterial remediation technology to promote the development and maturation of water-stable macroaggregates during the soilification process of the red mud. The resulting water-stable macroaggregates are structurally stable, not prone to degradation, highly drought-resistant, do not require the addition of inorganic or organic modifiers and repair agents, and are free of secondary residual pollution.

Description

Technical Field

[0001] The invention belongs to the technical field of ecological restoration and soil transformation of red mud, and specifically is a method for promoting the development of water-stable macroaggregates in red mud. Background Art

[0002] Red mud is a powdery, alkaline solid waste emitted during the alumina smelting process. Approximately 0.8 to 2 tons of red mud are emitted for every ton of alumina produced. Due to its unfavorable physical and chemical properties, such as salinity, corrosiveness, and radioactivity, its comprehensive utilization efficiency is low, with a utilization rate below 6%. Most of the red mud produced is stored in dams. During the long-term open-air storage of red mud, various heavy metal pollutants and alkalis have a serious negative impact on the groundwater, surface water, soil, and regional ecological functions surrounding the storage site, affecting the ecological, economic, and social value of the surrounding area.

[0003] Researching and implementing ecological restoration technologies at red mud dumps, and achieving revegetation and ecological restoration at these sites, are crucial steps in controlling red mud environmental risks, achieving large-scale red mud disposal, and ensuring the green and sustainable development of the alumina industry. These efforts are of great practical significance. However, the physical and chemical properties of red mud differ significantly from those of ordinary soil. Its poor physical structure, high salinity, and lack of nutrients severely hinder the settlement of pioneer species and the growth of plant roots. Therefore, soil-improving red mud is fundamental to revegetation and ecological restoration.

[0004] Currently, the main methods used to improve red mud soil are topsoil mulching and matrix amendment. Topsoil mulching involves transporting fresh soil from other areas and applying it to the surface of red mud dumps, combined with vegetation planting to improve the extreme environmental conditions. However, this method not only requires a large amount of soil for initial covering, but also requires regular replenishment of fresh soil and long-term monitoring. It is also prone to surface soil salinization. Matrix amendment improves the physical and chemical properties of red mud by adding exogenous amendments. The main amendments used include gypsum, organic fertilizers, and inorganic fertilizers. Gypsum can reduce the pH and alkalinity of red mud through a calcium-sodium replacement reaction, improving its physical structure. Organic fertilizers such as biosolids, compost, and straw can increase the organic matter content of red mud and reduce its bulk density and density. Inorganic fertilizers such as diammonium phosphate promote the growth of vegetation on red mud dumps. However, the disadvantages of matrix amendment are high resource consumption, high investment costs, the potential for secondary pollution, and the difficulty in establishing long-term, stable vegetation on the surface of red mud dumps.

[0005] The key to transforming red mud from a saline-alkaline waste residue into a soil-like matrix lies in the development of water-stable macroaggregates within the mud. Soil aggregates are porous structural units of varying scales formed by the combination of mineral particles and organic matter. They are the fundamental building blocks of soil structure and the foundation of its formation. Red mud contains high levels of silt and clay, is highly alkaline, and has a poor aggregate structure. This results in an extremely low content of water-stable macroaggregates, the essential components for red mud's ability to permeate, aerate, retain water and fertilizer, and resist drought and maintain moisture. Currently, topsoil mulching and matrix improvement methods commonly used for red mud soil improvement primarily focus on desalination, reducing aluminum toxicity, increasing organic matter content, and expanding vegetation cover. However, the formation and development of water-stable macroaggregates is slow. Even after the application of organic and inorganic amendments and remediation agents, the water-stable macroaggregates that do develop degrade due to the decomposition and disappearance of the agents. This ultimately hinders the self-renewal and maintenance of the vegetation ecosystem established on the red mud surface. Summary of the Invention

[0006] In response to the above problems, the present invention provides a method for promoting the development of water-stable macroaggregates in red mud. The method uses algae, fungi and bacteria to jointly repair and promote the development and maturation of water-stable macroaggregates in the process of red mud soilification. The method not only generates water-stable macroaggregates of red mud with stable structure and not easy to degenerate, but also has strong drought resistance, no need to add inorganic or organic modifiers and repair agents, no secondary residual pollution, simple operation, low cost, and easy large-scale application.

[0007] The present invention is specifically implemented through the following technical solutions. According to the present invention, a method for promoting the development of water-stable macroaggregates in red mud mainly includes the following steps:

[0008] (1) Scrape and collect blue-green and dark-green algae crusts from the surface of red mud that has been piled for 3 to 10 years in the red mud dump. The red mud area where the algae crust is located is a naturally piled red mud area that has not been artificially repaired. The sampling time is preferably after rainfall and when the average daytime temperature exceeds 20°C.

[0009] (2) The collected algae crusts were ground and diluted 1000-10000 times with sterile distilled water. The algae crusts were then inoculated onto BG11 solid culture plates containing 4-5% red mud (mass percentage) and cultured in a light incubator under the following conditions: light intensity of 3000-4000 lx, temperature of 25-30°C, light-dark ratio of 14h:10h, and culture time of 3-4 weeks. Then, the sheathing filamentous algae and the filamentous algae were separated from the BG11 solid culture plates and further purified on BG11 solid culture plates containing 4-5% red mud (mass percentage) until the purified sheathing filamentous algae and the filamentous algae were obtained.

[0010] (3) The purified Scalycosa and Tricholoma were propagated in sterile BG11 liquid culture medium, respectively, with an inoculation density of 0.8-1.2 mg / L. The culture conditions were: light intensity of 3000-4000 lx, temperature of 25-30 °C, and light-dark ratio of 12h:12h. The culture was terminated when the dry weight of algal cells exceeded 0.12 g / L (the dry weight of algal cells was determined by taking a certain volume of culture medium, drying it, and weighing it to calculate the dry weight of algal cells per liter of culture medium). The liquid culture medium containing the algal cells was centrifuged or filtered, and the filtrate was collected to obtain the propagation concentrate of Scalycosa and Tricholoma.

[0011] (4) The propagation concentrate of the sheathed filamentous algae and the propagation concentrate of the filamentous algae are mixed evenly in a volume ratio of 1:1 to obtain an algae-promoting liquid with an algae cell density of 2.0 to 3.0 g / L, and the algae-promoting liquid is evenly sprayed or poured on the surface of the red mud pile; the volume of the algae-promoting liquid required to be sprayed or poured per square meter of the red mud pile surface is equal to the mass of algae cells contained per square meter of the red mud pile surface divided by the algae cell density in the algae-promoting liquid. The mass of algae cells contained per square meter of the red mud pile surface is calculated according to the following formula:

[0012] ρ=k×(1-WSA)×(1-TN×100)

[0013] Where ρ is the mass of algae cells per square meter of red mud pile surface (unit: g / m 2 ); k is the conversion coefficient, its value is 7.73g / m 2 WSA is the water-stable macroaggregate content in red mud; TN is the total nitrogen content in red mud (%). WSA is measured according to the national standard NY / T 1121.19-2008, and TN is measured according to the national standard NY / T53-1987.

[0014] Spray water regularly to moisten the red mud so that the moisture content on the surface of the red mud pile is not less than 30%. When the average external temperature is below 8°C, the surface of the red mud needs to be covered with a film.

[0015] (5) When the surface of the red mud pile treated in step (4) grows a clear blue-green algae crust, and the total nitrogen content (TN) in the red mud is ≥0.1% and the total organic carbon content (TOC) is ≥1.0% (TN is measured in accordance with the national standard NY / T53-1987, and TOC is measured in accordance with the national standard HJ 658-2013), the surface red mud is plowed for the first time to mix the algae crust with the surface red mud, and the surface of the red mud pile after the first plowing is sprayed or irrigated with a bacteria-promoting liquid and a fungus-promoting liquid, and a second plowing is performed to mix the surface red mud, algae crust, bacteria-promoting liquid, and fungus-promoting liquid evenly. Water is sprayed regularly to moisten the red mud so that the moisture content on the surface of the red mud pile is not less than 30%. When the average external temperature is below 8°C, the red mud surface needs to be covered with a ground film.

[0016] The amount of bacteria-promoting liquid sprayed or poured on the surface of the red mud pile is 8 to 12 L per square meter.

[0017] The minimum dosage of fungus-promoting liquid for spraying or watering on the surface of red mud pile is calculated according to the following formula:

[0018]

[0019] Where X1 is the volume of fungus-promoting liquid sprayed or poured on the surface of red mud pile per square meter (unit: L / m 2 ); WSA is the content of water-stable macroaggregates in red mud; ANC is the acid neutralization capacity of red mud (unit: mmol H + ·g -1 ); M is the conversion factor, its value is 0.48mmol H + ·g -1 ·m 2 ·L -1 WSA is measured according to the national standard NY / T1121.19-2008. ANC can be determined using a long-term titration method. For example, 5g of red mud is mixed with 25mL of deionized water in a glass container and titrated with 0.01mol / L HCl. The endpoint pH of the titration is 4.5. If the pH exceeds 4.5 on the second day, titrate again with 0.01mol / L HCl to lower the pH to 4.5. This process is repeated until the pH no longer changes. The amount of hydrogen ions titrated is the ANC.

[0020] The bacteria-promoting solution used in this step can be prepared according to the following method:

[0021] (5.1) Inoculate Nourishia into sterilized Gao's medium No. 1 containing 0.5% red mud particles (mass percentage) and culture at 30-35°C with shaking until the absorbance OD 600 When the concentration is ≥1.3, the culture is stopped to obtain the living cell solution of Nourella;

[0022] (5.2) Inoculate the lactobacillus into a sterilized beef extract peptone medium containing 0.5% red mud particles (mass percentage) and culture at 30-35°C with shaking until the absorbance OD 600 When the value is ≥1.2, the culture is stopped to obtain the living cell liquid of Lactobacillus;

[0023] (5.3) Inoculate Paenibacillus polymyxa into sterilized medium A and culture at 30-35°C with shaking until the absorbance OD 600 When the pH value is ≥1.5, the culture is stopped to obtain the living cell solution of Paenibacillus polymyxa. The culture medium A uses deionized water as a solvent and comprises the following components: 150 g / L glucose, 3.0 g / L yeast extract, 2.0 g / L K2HPO4, and 5 g / L red mud particles;

[0024] (5.4) Mix the live cell solution of Nourella, the live cell solution of Lactobacillus, and the live cell solution of Paenibacillus polymyxa at a volume ratio of 1: (1.4-1.6): 2, and then add trehalose (the added mass of trehalose is 1 / 20 of the added mass of the live cell solution of Lactobacillus) to prepare a bacteria-promoting solution.

[0025] The fungus promotion solution used in this step can be prepared according to the following method: spores or mycelial fragments of Trichoderma or Aspergillus are inoculated into a sterilized potato dextrose agar solid medium, cultured at 30-35°C with shaking for 96-108 hours, and mature Trichoderma or Aspergillus spores on the surface of the potato dextrose agar solid medium are collected and placed in sterilized deionized water to prepare a spore concentrate. The number of spores in each milliliter of the spore concentrate is about 1.0×10 7 This spore concentrate is the fungus promoting liquid.

[0026] (6) When the pH value of the red mud on the surface of the red mud pile is lower than 9.0 and the content of water-stable macroaggregates is greater than 70%, salt-alkali tolerant plants can be sown for vegetation reconstruction. The salt-alkali tolerant plants include but are not limited to Suaeda salsa.

[0027] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical solution, the present invention can achieve considerable technological advancement and practicality, and has a wide range of utilization value. It has at least the following advantages:

[0028] (1) The present invention uses a combined technology of algae, bacteria, and fungi to promote the construction and development of water-stable aggregates in red mud. In the early stage, the key algae in the natural soil formation process of red mud, such as sheathed filamentous algae and common filamentous algae, are added to inject organic carbon and nitrogen into the red mud through nitrogen fixation and carbon fixation, providing nutrients and habitats for the development of heterotrophic bacteria in the next step. At the same time, the algae crust can initially bind and fix the red mud on the surface of the red mud pile, so that it is not eroded by water and wind and retains moisture, thereby promoting the initial development of water-stable aggregates. In the later stage, the key fungi Trichoderma or Aspergillus, the key actinomycete Nourella, and the key bacteria Lactobacillus and Bacillus polymyxa in the natural soil formation process of red mud are added. The fungi and bacteria use the organic nutrients injected by the algae to secrete organic acids to reduce the salinity and alkalinity of the red mud. The hyphae of the fungi and actinomycetes bind the red mud clay and powder particles to aggregate them into large-sized particles. The extracellular polymers (EPS) secreted by the microorganisms wrap the red mud particles to further form water-stable large aggregates with a stable mechanical structure.

[0029] (2) The present invention provides a calculation formula for the minimum dosage of algae-promoting liquid and fungus-promoting liquid by performing linear fitting analysis on experimental data, thereby reducing the dosage of microbial reagents and saving costs.

[0030] (3) The present invention simulates the natural soil formation process of red mud during open-air stacking. Based on the primary succession law of microorganisms in the natural soil formation process of red mud and the key bacterial species at different stages of red mud soil formation, algae, bacteria, and fungi that dominate the early and late stages of red mud soil formation are selected as promoting liquid components, and the corresponding key bacterial species are added in the early and late stages of red mud soil formation, respectively, in accordance with the primary succession law of the natural soil formation process. Therefore, a stable and self-sustaining microbial ecosystem can be established on the surface of the red mud pile under open conditions. No organic and inorganic modifiers or repair agents (such as gypsum, activated carbon, straw) are added, there is basically no secondary pollution, and there is no phenomenon of degradation of water-stable aggregates due to degradation and consumption of organic and inorganic modifiers or repair agents. The water-stable large aggregates of red mud generated by the method of the present invention are stable in structure and not easy to degenerate. After sowing, vegetation can be quickly established on the surface of the red mud. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a 1500x magnified SEM image of the agglomerates formed by algae crusts adhering to red mud particles after applying algae-promoting liquid to red mud:

[0032] Figure 2 This is a 1500-fold magnified SEM image of aggregates formed by fungal hyphae and actinomycete hyphae bound to red mud particles after the application of fungal and bacterial promoting solutions to red mud after the initial tillage.

[0033] Figure 3 This is a photo of the germination of Suaeda salsa planted in unremediated red mud.

[0034] Figure 4 This is a photo of the germination of Suaeda salsa planted after red mud was repaired according to the method of Example 1. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] In the following examples, if specific conditions are not specified, they are all carried out according to conventional conditions or the conditions recommended by the manufacturer. The raw materials and reagents used, if the manufacturer is not specified, are all conventional products that can be purchased commercially. The lactobacillus, polymyxa, Trichoderma, Aspergillus, and Nourse can be separated or purchased by themselves. For example, lactobacillus, polymyxa, Trichoderma, and Aspergillus are purchased from the mall Beina Chuanglian Biotechnology Co., Ltd., and the article numbers are BNCC356105, BNCC138393, BNCC341615, and BNCC363585 respectively; Nourse is purchased from the China Pharmaceutical Microorganism Culture Collection Administration Center, and the article number is CPCC205536.

[0037] Example 1

[0038] (1) Blue-green algae crusts were collected from the fifth layer of an open-air red mud dump that had not been artificially restored. The sampling time was preferably after rainfall and when the average daytime temperature exceeded 20°C.

[0039] (2) In the laboratory, the collected algae crusts were ground, diluted 5000-fold with sterile distilled water, and then inoculated onto BG11 solid culture medium plates containing 5% red mud (mass percentage). The plates were then cultured in a light incubator for 25 days under the following conditions: light intensity of 3500 lx, temperature of 28°C, and light-dark ratio of 14 h:10 h. The algae were isolated and purified using a microscope and a 96-well plate limiting dilution method to obtain S. scalycoides and S. scalycoides. The plates were then further cultured and purified on BG11 solid culture medium plates containing 5% red mud (mass percentage) until the purified S. scalycoides and S. scalycoides were obtained.

[0040] (3) The purified sheathed filamentous algae and filamentous algae were propagated in sterile BG11 liquid culture medium, respectively, with an inoculation density of 1.0 mg / L. The culture conditions were: light intensity 3500 lx, temperature 28 °C, light-dark ratio 12h:12h, and cultured until the dry weight of algal cells exceeded 0.12 g / L. The liquid culture medium containing algal cells was filtered and the filtrate was collected to obtain the propagation concentrated solution of sheathed filamentous algae and the propagation concentrated solution of filamentous algae.

[0041] (4) The propagation concentrate of the sheathed filamentous algae and the propagation concentrate of the common filamentous algae were mixed evenly in a volume ratio of 1:1 to obtain an algae-promoting liquid with an algae cell density of about 2.4 g / L. The algae-promoting liquid was evenly sprayed on the surface of the red mud in the flowerpot. The WSA (water-stable large aggregate content) of the red mud was 36.1%, and the TN (total nitrogen content) was 0.0103%. Water was sprayed regularly to moisten the surface of the red mud so that the moisture content of the surface red mud was maintained above 30%.

[0042] The volume of algae-promoting liquid required to be sprayed per square meter of red mud surface is equal to the mass of algae cells per square meter of red mud surface divided by the density of algae cells in the algae-promoting liquid. The mass of algae cells per square meter of red mud surface is calculated according to formula (1):

[0043] ρ=k×(1-WSA)×(1-TN×100) (1)

[0044] Where ρ is the mass of algae cells per square meter of red mud surface (unit: g / m 2 ), k is the conversion factor, its value is 7.73g / m 2 , WSA is the water-stable macroaggregate content in red mud, which is 36.1% in this example, and TN is the total nitrogen content in red mud (%), which is 0.0103% in this example. The mass of algae cells required to be sprayed per square meter of red mud surface is calculated by formula (1) to be 4.89 g / m 2 , and then concluded that the volume of algae-promoting liquid required to be sprayed per square meter of red mud surface is about 2.0L.

[0045] (5) When blue-green algae crusts grow on the red mud surface, the TN and TOC contents are measured. TN is 0.105% and TOC is 1.614%. The surface red mud is then plowed to mix the algae crusts and the surface red mud evenly. Bacteria-promoting liquid and fungi-promoting liquid are then sprayed on the red mud surface, and plowed a second time to mix the surface red mud, algae crusts, bacteria-promoting liquid, and fungi-promoting liquid evenly. The red mud is regularly sprayed with water to moisten the surface, ensuring a surface moisture content of no less than 30%.

[0046] The amount of the bacteria promoting liquid is 10L / m 2 The spraying amount of fungus promoting liquid is calculated by formula (2) as 3.54L / m 2 Formula (2) is as follows:

[0047]

[0048] Among them, X1 is the amount of fungus promoting liquid per square meter of red mud surface (unit: L / m 2 ); WSA is the content of water-stable macroaggregates in red mud, and in this embodiment, WSA is 49.6%; ANC is the acid neutralization capacity of red mud, and in this embodiment, ANC is 3.37 mmol H + ·g -1 ; M is the conversion factor, its value is 0.48mmol H + ·g -1 ·m 2 ·L -1 .

[0049] (6) After 6 months, the physical and chemical properties of the surface red mud and the effect of aggregate development were evaluated. The pH value of the red mud decreased from 12.7 to 8.4, the content of water-stable large aggregates increased from 36.1% to 62.4%, and the average weight diameter of the aggregates increased from 0.14 mm to 0.33 mm. When Suaeda salsa was sown in the red mud, the germination rate of Suaeda salsa decreased from 0% to ( Figure 3 ) was increased to 57.1% after the red mud was repaired according to this embodiment ( Figure 4 ).

[0050] The bacteria-promoting solution used in this example was prepared as follows:

[0051] Nourella was inoculated into sterilized Gao's medium No. 1 containing 0.5% red mud particles (mass percentage) and cultured at 32°C with shaking until the absorbance OD 600 When the pH value is ≥1.3, the culture is stopped to obtain the living cell liquid of Nourella; the lactobacillus is inoculated into the sterilized beef extract peptone medium containing 0.5% red mud particles (mass percentage), and the culture is shaken at 32°C until the absorbance OD 600 Stop culturing when the pH value is ≥1.2 to obtain the living cell solution of Lactobacillus; inoculate Paenibacillus polymyxa into the sterilized culture medium A and culture at 32°C with shaking until the absorbance OD 600 ≥1.5, and the culture is stopped to obtain a Paenibacillus polymyxa live cell solution. The culture medium A uses deionized water as a solvent and comprises: 150 g / L glucose, 3.0 g / L yeast extract, 2.0 g / L K2HPO4, and 5 g / L red mud particles. The live cell solution of Nourella, the live cell solution of Lactobacillus, and the live cell solution of Paenibacillus polymyxa are uniformly mixed in a volume ratio of 1:1.5:2, and then trehalose is added, wherein the added mass of trehalose is 1 / 20 of the added mass of the Lactobacillus live cell solution, to prepare a bacteria-promoting solution.

[0052] The fungus promoting solution used in this example was prepared as follows:

[0053] The spores or mycelial fragments of Trichoderma were inoculated into sterilized potato dextrose agar solid medium and cultured at 32°C with shaking for 108 h. The mature Trichoderma spores on the surface of the potato dextrose agar solid medium were collected and placed in sterilized deionized water to prepare spore concentrate. The number of spores per ml of spore concentrate was about 1.0 × 10 7 This spore concentrate is the fungus promoting liquid.

[0054] Figure 1 This is a SEM image of the agglomerates formed by the algae crust adhering to the red mud particles after the algae promotion liquid was applied in Example 1, magnified 1500 times. It can be seen that the algae crust and the red mud particles adhere to each other to form agglomerates.

[0055] Figure 2 This is a 1500x magnified SEM image of the aggregates formed by fungal hyphae and actinomycete hyphae bound to red mud particles after applying the fungal promoting liquid and the bacterial promoting liquid in Example 1. It can be seen that the hyphae bound to the red mud particles formed large aggregates. Figure 1 , it was found that after applying algae-promoting liquid, fungus-promoting liquid and bacteria-promoting liquid, the average volume of aggregate particles increased significantly.

[0056] The above description is merely an embodiment of the present invention and does not constitute any form of limitation to the present invention. The present invention may also have other forms of embodiments based on the above structures and functions, which are not listed here one by one. Therefore, any simple modification, equivalent changes, and modifications made to the above embodiments by any person skilled in the art in accordance with the technical essence of the present invention without departing from the scope of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for promoting the development of water-stable macroaggregates in red mud, characterized in that: The following steps are involved: (1) Scrape and collect blue-green and dark-green algae crusts from the surface of red mud that has been piled for 3 to 10 years in the red mud dump. The red mud area where the algae crusts are located is a naturally piled red mud area that has not been artificially repaired; (2) Grinding the collected algae crusts, diluting them 1000-10000 times with sterile distilled water, and then inoculating them onto BG11 solid culture medium plates containing 4-5% red mud by mass, culturing them in a light incubator for 3-4 weeks, separating the sheathed filamentous algae and the filamentous algae from the BG11 solid culture medium plates, and continuing to purify them on BG11 solid culture medium plates containing 4-5% red mud by mass until the purified sheathed filamentous algae and the filamentous algae are obtained; (3) Propagating the purified Scalycosa and Tricholoma in sterile BG11 liquid culture medium, respectively, until the algal cell dry weight exceeds 0.12 g / L, terminating the culture, centrifuging or filtering the liquid culture medium containing the algal cells, and collecting the filtrate to obtain the propagation concentrate of Scalycosa and Tricholoma; (4) mixing the propagation concentrate of the sheathed filamentous algae and the propagation concentrate of the filamentous algae in a volume ratio of 1:1 to obtain an algae-promoting liquid, spraying or pouring the algae-promoting liquid evenly on the surface of the red mud pile, and regularly sprinkling water to moisten the red mud so that the moisture content of the red mud pile surface is not less than 30%, and covering the red mud surface with a mulch film when the average external temperature is lower than 8°C; (5) When obvious blue-green algae crust grows on the surface of the red mud pile treated in step (4), and the total nitrogen content in the red mud is ≥0.1% and the total organic carbon content is ≥1.0%, the surface red mud is plowed for the first time to mix the algae crust with the surface red mud evenly, and the surface of the red mud pile after the first plowing is sprayed or irrigated with a bacteria-promoting liquid and a fungus-promoting liquid, and a second plowing is performed to mix the surface red mud, the algae crust, the bacteria-promoting liquid, and the fungus-promoting liquid evenly; water is sprayed regularly to moisten the red mud so that the moisture content on the surface of the red mud pile is not less than 30%, and when the average external temperature is lower than 8°C, the surface of the red mud needs to be covered with a ground film; (6) After the treatment in step (5), when the pH value of the red mud on the surface of the red mud pile is lower than 9.0 and the content of water-stable macroaggregates is greater than 70%, salt-alkali tolerant plants are sown for vegetation reconstruction.

2. The method for promoting the development of water-stable macroaggregates in red mud according to claim 1, characterized in that: The culture conditions of step (2) are: light intensity 3000-4000 lx, temperature 25-30° C., and light-dark ratio 14h:10h.

3. The method for promoting the development of water-stable macroaggregates in red mud according to claim 1, characterized in that: During the propagation in step (3), the inoculation density of the herbaceous filamentous algae and the filamentous algae were both 0.8-1.2 mg / L, and the culture conditions were: light intensity 3000-4000 lx, temperature 25-30° C., and light-dark ratio 12h:12h.

4. The method for promoting the development of water-stable macroaggregates in red mud according to claim 1, wherein: The algae cell density in the algae-promoting liquid obtained in step (4) is 2.0 to 3.0 g / L. The volume of the algae-promoting liquid required to be sprayed or poured per square meter of the red mud pile surface is equal to the mass of algae cells per square meter of the red mud pile surface divided by the algae cell density in the algae-promoting liquid. The mass of algae cells per square meter of the red mud pile surface is calculated according to the following formula: ρ=k×(1-WSA)×(1-TN×100) Where ρ is the mass of algae cells per square meter of red mud pile surface, unit: g / m 2 ; k is the conversion coefficient, its value is 7.73g / m 2 ; WSA is the content of water-stable large aggregates in red mud; TN is the total nitrogen content in red mud (%).

5. The method for promoting the development of water-stable macroaggregates in red mud according to claim 1, wherein: The amount of bacteria-promoting liquid sprayed or poured on the surface of the red mud pile in step (5) is 8 to 12 L / m 2 .

6. The method for promoting the development of water-stable macroaggregates in red mud according to claim 1 or 5, characterized in that: The bacteria-promoting liquid is prepared according to the following method: (1) Nourella was inoculated into sterilized Gao's medium No. 1 containing 0.5 (wt.)% red mud particles and cultured at 30-35°C with shaking until the absorbance OD 600 When the concentration is ≥1.3, the culture is stopped to obtain the living cell solution of Nourella; (2) Lactobacillus was inoculated into a sterilized beef extract peptone medium containing 0.5 wt.% red mud particles and cultured at 30-35 °C with shaking until the absorbance OD 600 When the value is ≥1.2, the culture is stopped to obtain the living cell liquid of Lactobacillus; (3) Inoculate Paenibacillus polymyxa into sterilized culture medium A and culture at 30-35°C with shaking until the absorbance OD 600 When the pH value is ≥1.5, the culture is stopped to obtain the living cell solution of Paenibacillus polymyxa. The culture medium A uses deionized water as a solvent and comprises the following components: 150 g / L glucose, 3.0 g / L yeast extract, 2.0 g / L K2HPO4, and 5 g / L red mud particles; (4) The live cell solution of Nourella, the live cell solution of Lactobacillus, and the live cell solution of Paenibacillus polymyxa were mixed evenly in a volume ratio of 1: (1.4-1.6): 2, and then trehalose was added to prepare a bacteria-promoting solution, wherein the added mass of trehalose was 1 / 20 of the added mass of the live cell solution of Lactobacillus.

7. The method for promoting the development of water-stable macroaggregates in red mud according to claim 1, wherein: The amount of fungus-promoting liquid sprayed or watered on the surface of the red mud pile is calculated according to the following formula: Among them, X1 is the amount of fungus promoting liquid sprayed or watered per square meter of red mud pile surface, unit: L / m 2 ; WSA is the content of water-stable macroaggregates in red mud; ANC is the acid neutralization capacity of red mud, unit: mmol H + ·g -1 ; M is the conversion factor, its value is 0.48mmol H + ·g -1 ·m 2 ·L -1 .

8. The method for promoting the development of water-stable macroaggregates in red mud according to claim 1 or 7, characterized in that: The fungus promotion liquid is prepared according to the following method: spores or mycelial fragments of Trichoderma or Aspergillus are inoculated into a sterilized potato dextrose agar solid medium, cultured at 30-35°C with shaking for 96-108 hours, and mature Trichoderma or Aspergillus spores on the surface of the potato dextrose agar solid medium are collected and placed in sterilized deionized water to prepare a spore concentrate, wherein the number of spores per milliliter of the spore concentrate is 1.0×10 7 to obtain fungus promoting liquid.

9. The method for promoting the development of water-stable macroaggregates in red mud according to claim 1, characterized in that: The salt-alkali tolerant plants include Suaeda salsa.

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