Method for preparing soil conditioner from ardealite and red mud as well as product and application of soil conditioner

Abstract

The invention discloses a method for preparing a soil conditioner from ardealite and red mud as well as a product and application of the soil conditioner. The method comprises the following steps: mixing camellia oleifera residues, red mud and ardealite, uniformly stirring, aging, carrying out hydrothermal reaction, drying, and grinding to obtain stable powder; mixing plant ash, crop powder and straw powder, and uniformly stirring to obtain driving powder; mixing the aronia melanocarpa primary pulp and the sea-buckthorn primary pulp, and uniformly stirring to obtain probiotic pulp; mixing the probiotic slurry, the driving powder and the stabilizing powder, uniformly stirring, and adding compound microorganisms for fermentation to obtain the soil conditioner. The preparation process is simple, and the efficient microbial fermentation soil is prepared by fully utilizing the two industrial solid wastes of the ardealite and the red mud and carrying out synergistic reasonable proportioning and compound microbial fermentation. The prepared microbial fermentation soil is extremely low in heavy metal leaching toxicity, the significant yield increase of lettuce and leaf lettuce planted in the repaired land parcel can be fully achieved, and the highest yield increase rates reach 156.72% and 191.05% respectively.

Description

Technical Field

[0001] The present invention relates to a method for preparing a soil conditioner by using phosphogypsum and red mud, and its product and application, belonging to the field of soil conditioners. Background Art

[0002] As the main by-product of the phosphate fertilizer industry, phosphogypsum has a complex composition, containing not only a large amount of calcium sulfate, but also rich in phosphates, fluorides, heavy metals (such as cadmium, manganese) and radioactive element radium. The long-term storage of these harmful substances undoubtedly poses a severe challenge to the environment and ecosystem. Specifically, the storage of phosphogypsum will not only cause groundwater pollution, through the leaching effect of rainwater, fluorides, phosphates and heavy metals seep into the groundwater system, leading to water quality acidification and heavy metal enrichment problems, but also cause soil degradation, acidic leachate destroys the soil structure, inhibits the activity of microorganisms, and then reduces the yield and quality of crops. In addition, the annual global discharge of phosphogypsum exceeds 300 million tons, while the comprehensive utilization rate is less than 15%, which is not only a great waste of resources, but also occupies a large amount of precious land resources, exacerbating the tension of land resources. Red mud, as a strongly alkaline waste residue in the alumina production process, usually has a pH value between 10 and 12, containing various components such as aluminum, iron oxides and sodium salts. The storage of red mud also brings serious environmental problems. On the one hand, its strong alkaline characteristics will cause soil salinization, make the soil harden, and it is difficult for vegetation to grow, thus destroying the balance of the ecosystem; on the other hand, the heavy metals such as vanadium and chromium remaining in the red mud are easily dissolved under alkaline conditions, posing a serious threat to the safety of groundwater. The annual discharge of red mud in China exceeds 100 million tons, while the utilization rate is only 4%, the storage cost is high, and with the continuous development of the alumina industry, the discharge of red mud is increasing year by year, and its environmental risks cannot be ignored. Therefore, exploring the resource utilization ways of phosphogypsum and red mud not only helps to alleviate the environmental pressure brought by them, but also can realize the effective recovery and reuse of resources, which has important practical significance and strategic value.

[0003] Phosphogypsum and red mud have certain complementarity in physical and chemical properties. Phosphogypsum is weakly acidic (pH 3 - 5), while red mud is strongly alkaline. After mixing the two, acid-base neutralization can be achieved, adjusting the pH value of the mixed system to neutral or near neutral, thereby reducing environmental risks. In addition, phosphogypsum is rich in calcium and sulfur elements, while red mud is rich in nutrients such as iron and aluminum oxides. The combination of the two can significantly improve soil structure, enhance soil fertility and water retention capacity, and promote the absorption and utilization of mineral elements by plants. Microbial fermentation technology plays an important role in the synergistic utilization of phosphogypsum and red mud. By adding organic conditioners such as distiller's grains and sludge, and using the aerobic fermentation process to generate organic matter such as humus, the fertility level of the soil can be further improved. At the same time, the metabolites (such as polysaccharides and organic acids) produced by microorganisms during the fermentation process can form stable complexes with heavy metals, reducing their bioavailability, thereby achieving the passivation treatment of heavy metals.

[0004] The synergistic resource utilization of phosphogypsum and red mud through microbial fermentation technology has both environmental remediation and agricultural application values. Its theoretical feasibility has been verified through acid-base neutralization, nutrient complementarity, and microbial passivation mechanisms. From a social perspective, it helps to promote the low-carbon circular utilization of industrial solid waste and contribute to the construction of ecological civilization. However, to achieve the industrial application of this technology, it is necessary to further optimize the compatibility of fermentation inoculants and production process parameters. In the future, it is necessary to continue to deeply study the key technologies and influencing factors in the microbial fermentation process, explore more efficient and environmentally friendly preparation processes and application models. At the same time, strengthen cooperation and exchanges with relevant enterprises and research institutions, promote the transformation and popularization of the achievements of this technology, and make greater contributions to China's environmental protection cause and agricultural sustainable development. Summary of the Invention

[0005] Object of the Invention: The technical problem to be solved by the present invention is to provide a method for preparing a soil conditioner using phosphogypsum and red mud, as well as its product and application.

[0006] Technical Solution: To solve the above technical problem, the present invention provides a method for preparing a soil conditioner using phosphogypsum and red mud, comprising the following steps:

[0007] (1) Mix camellia oleifera residue, red mud, and phosphogypsum, stir evenly, age, perform hydrothermal reaction, dry and then grind into powder to obtain stable powder;

[0008] (2) Mix plant ash, crop powder, and straw powder, stir evenly to obtain driving powder;

[0009] (3) Mix aronia melanocarpa original pulp and seabuckthorn original pulp, stir evenly to obtain probiotic pulp;

[0010] (4) Mix the probiotic slurry, feed-driving powder, and stabilizing powder, stir evenly, add the complex microorganism for fermentation to obtain the soil conditioner; the complex microorganism consists of actinomycetes, bacillus, and functionalized additional bacteria.

[0011] Among them, the mass ratio of the camellia oleifera residue, red mud, and phosphogypsum in step (1) is 10 - 30:15 - 45:100.

[0012] Among them, the aging time in step (1) is 12 - 36 hours.

[0013] Among them, the temperature of the hydrothermal reaction in step (1) is 120 - 360 °C, the time is 6 - 24 hours, and the volume-mass ratio of the liquid-solid ratio is 1 - 5:1 mL / g.

[0014] Among them, the crop powder in step (2) is any one of corn flour, wheat flour, sweet potato flour, cassava flour, kudzu root flour, oat flour, and potato flour.

[0015] Among them, the mass ratio of the plant ash, crop powder, and straw powder in step (2) is 2.5 - 7.5:5 - 25:100.

[0016] Among them, the mass ratio of the aronia melanocarpa puree and seabuckthorn puree in step (3) is 15 - 45:100.

[0017] Among them, the mass ratio of the probiotic slurry, feed-driving powder, and stabilizing powder in step (4) is 0.5 - 4.5:20 - 60:100.

[0018] Among them, the mass of the complex microorganism in step (4) accounts for 0.05% - 0.55% of the total mass of the probiotic slurry, feed-driving powder, stabilizing powder, and complex microorganism.

[0019] Among them, the complex microorganisms are all bacterial powders.

[0020] Among them, the mass ratio of the actinomycetes, bacillus, and functionalized additional bacteria in step (4) is 0.25 - 1.75:0.25 - 1.75:1.

[0021] Among them, the actinomycetes in step (4) is any one of Streptomyces microflavus var. lactosus, Streptomyces microflavoviridis, Cellulomonas falcata, Streptomyces albogriseolus, or Streptomyces vinaceusdrappus.

[0022] Among them, the bacillus in step (4) is any one of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, Paenibacillus validus, or Virgibacillus halophilus.

[0023] Among them, the functionalized additional bacteria described in step (4) are any one of Halomonas sulfidovorans, Halorubrum sulfidifaciens, Pseudonocardia sulfidoxidans, Comamonas phosphatis, Bradyrhizobium diazoefficiens, Flavobacterium denitrificans, Azospirillum brasilense, Cycloclasticus denitrificans, Azotobacter beijerinckii, Azotobacter vinelandii, Herbaspirillum diazotrophicus, Rhodobacter azotoformans, Cellulomonas diazotrophica, Azotobacter armeniacus or Azotobacter paludis.

[0024] Among them, the fermentation time described in step (4) is 5 to 25 days, and the fermentation temperature is 10 to 50 °C.

[0025] The present invention also provides a soil conditioner prepared by the said method.

[0026] The present invention also provides the application of the said soil conditioner in improving plant yield or repairing heavy metal contaminated soil.

[0027] Reaction mechanism

[0028] Under hydrothermal conditions, the alkaline components in red mud react with the acidic components in phosphogypsum to produce water and corresponding salts, thereby reducing the alkalinity of red mud. At the same time, the minerals in red mud undergo phase transformation and react with the gypsum in phosphogypsum to form hydrated gel products. Phosphogypsum releases sulfate ions under hydrothermal conditions, and these sulfate ions react with aluminum ions in red mud and combine with calcium-based minerals to form ettringite, thereby filling the micro-pores of the material and improving the density of the matrix. Heavy metals and fluorine pollutants in red mud and phosphogypsum are effectively immobilized in ettringite and hydrated cementitious products. At the same time, under the hydrothermal environment, camellia oleifera residue undergoes a series of complex chemical transformations, involving processes such as carbonization, pyrolysis, and the formation of xylooligosaccharides. The lignin, cellulose, and hemicellulose contained in it undergo pyrolysis, dehydration, and carbonization processes under hydrothermal conditions. The generated organic products and hydrothermal biochar can adsorb substances such as iron, aluminum, silicon, sodium, titanium, and calcium in red mud, and combine with the residual organic phosphorus, inorganic phosphorus, fluorides, and organic matter released from phosphogypsum, and strengthen the hydrated cementitious and geopolimerization reactions between red mud and phosphogypsum mineral phases through phase transformation, chelation, and charge balance pathways. The organic matter in camellia oleifera residue decomposes into small-molecule organic acids and alcohols under high temperature and pressure, which can undergo complexation reactions with metal ions in red mud and phosphogypsum to form stable complexes. At the same time, the residual organic phosphorus and inorganic phosphorus in phosphogypsum will be further released and react with the organic matter in camellia oleifera residue to form phosphate ester compounds. The organic matter in camellia oleifera residue, aluminum oxide and iron oxide in red mud, and calcium sulfate dihydrate in phosphogypsum interact with each other during the hydrothermal reaction process to form a complex chemical network. During the mixed fermentation process, cellulose and hemicellulose in the mixture are decomposed into oligosaccharides and monosaccharides, and are further utilized by composite microorganisms to generate metabolic products such as organic acids and alcohols. At the same time, cellulose, hemicellulose, and lignin can gradually be transformed into humus under the action of microorganisms, increasing the organic matter content of the soil and improving soil fertility. Bacillus and actinomycetes ferment synergistically, utilize the nutrient elements provided by the hydrothermal decomposition of stabilized powder, plant ash, and camellia oleifera residue, and enzymatically decompose the straw powder and hydrothermal carbonization products of camellia oleifera residue to form various organic acids and alcohols, and through the further synergistic nitrogen and sulfur cycle effects of functional microorganisms, achieve the enrichment and resynthesis of polyphenols, vitamins, and organic acids. Under the synergistic action of composite microorganisms, polyphenols in aronia melanocarpa raw pulp and seabuckthorn raw pulp are partially degraded to generate small-molecule polyphenols with higher biological activity, thereby improving the antioxidant and antibacterial functions of the fermented soil. Composite microorganisms use the hydrothermal carbonization products of camellia oleifera residue as a carrier to adsorb, enrich, and transform microbial metabolites, and promote the full reaction of metabolic active substances with the active substances in the mixed probiotic pulp. The product fermented through the synergistic action of composite microorganisms has a high organic matter content and rich nutritional components. The harmful substances in red mud and phosphogypsum react with the enzyme and metabolite products to achieve transformation and effective fixation.

[0029] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: The preparation process of the present invention is simple. By making full use of two industrial solid wastes, phosphogypsum and red mud, and through collaborative and reasonable batching and compound microbial fermentation, highly efficient microbial fermentation soil is prepared. The prepared microbial fermentation soil has extremely low heavy metal leaching toxicity, and can fully achieve a significant increase in the yield of lettuce and lettuce grown in the repaired plot, with the highest yield increase rates reaching 156.72% and 191.05% respectively. Brief Description of the Drawings

[0030] Figure 1 It is a flow chart of the present invention. Detailed Embodiments

[0031] The technical solution of the present invention will be further described below with reference to the drawings.

[0032] Preparation of heavy metal contaminated soil: Weigh 1 kg of uncontaminated soil sample, then add 10 mg of thallium to the soil sample, add water to the soil according to the liquid-solid ratio of 1:1 ml / mg, stir evenly, and obtain the tested heavy metal contaminated soil sample after aging for 24 hours;

[0033] Red mud: The red mud is provided by Shandong Zibo Zhengheng Aluminum Industry Co., Ltd. The main detected components include: 38.52% Fe2O3, 27.83% Al2O3, 12.49% SiO2, 11.36% Na2O, 5.61% TiO2, 0.57% CaO, 0.34% SO3 and other components (inevitable impurities and loss on ignition);

[0034] Camellia oleifera residue: The Camellia oleifera residue is provided by Hunan Dasanxiang Camellia Oil Co., Ltd. The main detected components include: 11.82% oil, 23.65% protein, 16.52% tea saponin, 35.65% cellulose and 12.36% ash;

[0035] Phosphogypsum: The phosphogypsum is taken from Guizhou Xifeng Phosphate Mine Co., Ltd. The main components in the phosphogypsum sample include 52.70% SO3, 37.01% CaO, 4.37% SiO2, 2.07% Al2O3, 1.63% P2O5 and other components (inevitable impurities and loss on ignition).

[0036] Example 1 Influence of the mass ratio of Camellia oleifera residue, red mud and phosphogypsum on the performance of the prepared soil conditioner

[0037] Mix camellia oleifera residue, red mud, and phosphogypsum at mass ratios of 2.5:15:100, 5:15:100, 7.5:15:100, 10:7.5:100, 10:10:100, 10:12.5:100, 10:15:100, 20:15:100, 30:15:100, 10:30:100, 20:30:100, 30:30:100, 10:45:100, 20:45:100, 30:45:100, 30:50:100, 30:55:100, 30:60:100, 32.5:45:100, 35:45:100, 37.5:45:100 respectively. Stir evenly and age for 12 hours to obtain the initial mixture of paste residue. Place the initial mixture of paste residue into a reaction kettle for hydrothermal reaction to obtain a stabilized material. Then take out the stabilized material, dry it and grind it into powder to obtain a stable powder. The liquid-solid ratio of water to the initial mixture of paste residue is 1:1 mL / g, the hydrothermal temperature is 120 °C, and the hydrothermal time is 6 hours. Mix plant ash, crop powder, and straw powder at a mass ratio of 2.5:5:100, stir evenly to obtain a driving powder, where the crop powder is corn powder. Mix aronia (scientific name: Aronia melanocarpa) puree and sea buckthorn puree at a mass ratio of 15:100, stir evenly to obtain a probiotic puree. Mix the probiotic puree, driving powder, and stable powder at a mass ratio of 0.5:20:100, stir evenly, and add composite microorganisms for fermentation to obtain a soil conditioner. The fermentation time is 5 days, the fermentation temperature is 10 °C. The composite microorganisms are composed of actinomycetes, bacillus, and functionalized additional bacteria. The mass ratio of the added composite microorganisms is 0.05%, and the mass ratio of actinomycetes, bacillus, and functionalized additional bacteria is 0.25:0.25:1. The actinomycetes are Streptomyces microflavus var. lactose (CGMCC 4.1007); the bacillus is Bacillus subtilis (CGMCC 1.821); the functionalized additional bacteria is Sulfidomonas sulfuroxidans (CGMCC 1.6324).

[0038] Comparative experiment on the cultivation of lettuce and lettuce: Select two identical plots to grow lettuce and lettuce, namely Plot No. 1 and Plot No. 2. The processes of seedling selection, planting, and plant protection for lettuce or lettuce are the same. During the entire growth period, no soil conditioner is applied to Plot No. 1, and a soil conditioner (2 kg per square meter) is applied to Plot No. 2 before transplanting seedlings. After the planting period, harvest the lettuce or lettuce, wash, dry, and weigh them.

[0039] Lettuce yield increase rate: The weight difference between the lettuce harvested from Plot No. 2 and the lettuce harvested from Plot No. 1 is divided by the weight of the lettuce harvested from Plot No. 1 to obtain the lettuce yield increase rate.

[0040] Yumai lettuce yield increase rate: The weight difference between the Yumai lettuce harvested from Plot No. 2 and the Yumai lettuce harvested from Plot No. 1 is divided by the weight of the Yumai lettuce harvested from Plot No. 1 to obtain the Yumai lettuce yield increase rate.

[0041] Preparation of repaired heavy metal contaminated soil: The soil conditioner prepared in this example and the heavy metal contaminated agricultural land soil are mixed according to a mass ratio of 5:100, stirred evenly, evenly sprinkled with water, and aged for 7 days to obtain the repaired heavy metal contaminated agricultural land soil.

[0042] Heavy metal toxicity leaching test: The toxicity leaching test is carried out on the heavy metal contaminated soil samples before and after repair in accordance with the "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method" (HJ / T 299-2007).

[0043] Thallium ion concentration detection: The thallium concentration in the leachate is determined in accordance with the "Determination of Thallium in Water Graphite Furnace Atomic Absorption Spectrophotometry" (HJ 748-2015).

[0044] The test results of this example are shown in Table 1.

[0045] Table 1 Influence of the mass ratio of camellia oleifera residue, red mud, and phosphogypsum on the performance of the prepared soil conditioner

[0046]

[0047] As can be seen from Table 1, when the mass ratio of oil-tea camellia residue, red mud, and phosphogypsum is less than 10:15:100 (as in Table 1, the mass ratio of oil-tea camellia residue, red mud, and phosphogypsum = 7.5:15:100, 5:15:100, 2.5:15:100, 10:12.5:100, 10:10:100, 10:7.5:100 and lower ratios not listed in Table 1), the addition of oil-tea camellia residue and red mud is less, and the reaction of oil-tea camellia residue, red mud, and phosphogypsum is insufficient during the hydrothermal reaction process. The activation and stabilization effects of phosphogypsum are poor, resulting in a decline in the performance of the prepared fermented soil. The yield increase rates of lettuce and lettuce obtained by planting both decrease significantly as the mass ratio of oil-tea camellia residue, red mud, and phosphogypsum decreases, and the thallium leaching concentration increases significantly as the mass ratio of oil-tea camellia residue, red mud, and phosphogypsum decreases. When the mass ratio of oil-tea camellia residue, red mud, and phosphogypsum is equal to 10 - 30:15 - 45:100 (as in Table 1, the mass ratio of oil-tea camellia residue, red mud, and phosphogypsum = 10:15:100, 20:15:100, 30:15:100, 10:30:100, 20:30:100, 30:30:100, 10:45:100, 20:45:100, 30:45:100), under hydrothermal conditions, the alkaline components in red mud react with the acidic components in phosphogypsum to produce water and corresponding salts, thereby reducing the alkalinity of red mud. At the same time, the minerals in red mud undergo phase transformation and react with the gypsum in phosphogypsum to produce hydrated gel products. Phosphogypsum will release sulfate ions under hydrothermal conditions, and these sulfate ions react with aluminum ions in red mud and combine with calcium-based minerals to form ettringite, thereby filling the microscopic pores of the material and improving the compactness of the matrix. Heavy metals and fluorine pollutants in red mud and phosphogypsum are effectively solidified in ettringite and hydrated gel products. At the same time, in the hydrothermal environment, a series of complex chemical transformations occur in oil-tea camellia residue, involving processes such as carbonization, pyrolysis, and the formation of xylooligosaccharides. The lignin, cellulose, and hemicellulose contained in it undergo pyrolysis, dehydration, and carbonization processes under hydrothermal conditions. The generated organic products and hydrothermal biochar can adsorb substances such as iron, aluminum, silicon, sodium, titanium, and calcium in red mud, and combine with the residual organic phosphorus, inorganic phosphorus, fluorides, and organic matter released from phosphogypsum. Through phase transformation, chelation, and charge balance pathways, the hydration gelation and geopolimerization reactions between red mud and phosphogypsum mineral phases are strengthened. The small-molecule organic acids and alcohols generated by the decomposition of organic matter in oil-tea camellia residue under high temperature and high pressure can undergo complexation reactions with metal ions in red mud and phosphogypsum to form stable complexes. At the same time, the residual organic phosphorus and inorganic phosphorus in phosphogypsum will be further released and react with the organic matter in oil-tea camellia residue to form phosphate ester compounds. The organic matter in oil-tea camellia residue, aluminum oxide and iron oxide in red mud, and calcium sulfate dihydrate in phosphogypsum interact with each other during the hydrothermal reaction process to form a complex chemical network. Finally, the yield increase rate of lettuce is higher than 123% and the yield increase rate of lettuce is higher than 134%.When the mass ratio of camellia seed cake, red mud, and phosphogypsum is greater than 30:45:100 (as shown in Table 1, when the mass ratio of camellia seed cake, red mud, and phosphogypsum = 30:50:100, 30:55:100, 30:60:100, 32.5:45:100, 35:45:100, 37.5:45:100 and higher ratios not listed in Table 1), the addition of camellia seed cake and red mud is excessive. During the hydrothermal reaction process, the reaction of camellia seed cake, red mud, and phosphogypsum is unbalanced, resulting in a decline in the performance of the prepared fermentation soil. The yield increase rates of the lettuce and lettuce obtained by planting both decrease significantly as the mass ratio of camellia seed cake, red mud, and phosphogypsum further increases, and the thallium leaching concentration increases significantly as the mass ratio of camellia seed cake, red mud, and phosphogypsum further increases.

[0048] Therefore, generally speaking, considering the benefits and costs, when the mass ratio of camellia seed cake, red mud, and phosphogypsum is equal to 10 - 30:15 - 45:100, it is most beneficial to improve the performance of the prepared soil conditioner.

[0049] Effect of the mass ratio of plant ash, crop powder, and straw powder in Example 2 on the performance of the prepared soil conditioner

[0050] Mix camellia oil residue, red mud, and phosphogypsum in a mass ratio of 30:45:100, stir evenly, and age for 24 hours to obtain the initial mixture paste residue. Place the initial mixture paste residue into a reaction kettle for hydrothermal reaction to obtain a stabilized material. Then take out the stabilized material, dry it, and grind it into powder to obtain a stable powder. The liquid-solid ratio of water to the initial mixture paste residue is 3:1 mL / g, the hydrothermal temperature is 240 °C, and the hydrothermal time is 15 hours. Mix plant ash, crop powder, and straw powder in mass ratios of 1:5:100, 1.5:5:100, 2:5:100, 2.5:2.5:100, 2.5:3:100, 2.5:4:100, 2.5:5:100, 5:5:100, 7.5:5:100, 2.5:15:100, 5:15:100, 7.5:15:100, 2.5:25:100, 5:25:100, 7.5:25:100, 7.5:27.5:100, 7.5:30:100, 7.5:32.5:100, 8:25:100, 8.5:25:100, 9:25:100, stir evenly to obtain a driving material powder, where the crop powder is wheat flour. Mix aronia berry puree and seabuckthorn puree in a mass ratio of 30:100, stir evenly to obtain a probiotic puree. Mix the probiotic puree, driving material powder, and stable powder in a mass ratio of 2.5:40:100, stir evenly, add composite microorganisms for fermentation to obtain a fermented soil. The fermentation time is 15 days, the fermentation temperature is 30 °C. The composite microorganisms are composed of actinomycetes, bacillus, and functionalized additional bacteria. The mass ratio of the added composite microorganisms is 0.3%. The mass ratio of actinomycetes, bacillus, and functionalized additional bacteria is 1:1:1. The actinomycetes are Streptomyces microflavoviridis (CGMCC 4.7391); the bacillus is Bacillus licheniformis (CGMCC 1.10314); the functionalized additional bacteria are Halorhodospira sulfidigenes (CGMCC 1.6307).

[0051] The comparative tests of lettuce and lettuce growth rate, lettuce growth rate, preparation of heavy metal contaminated soil after remediation, heavy metal toxicity leaching test, and thallium ion concentration detection are the same as in Example 1. The test results of this example are shown in Table 2.

[0052] Table 2 Influence of the mass ratio of plant ash, crop powder, and straw powder on the performance of the prepared soil conditioner

[0053]

[0054]

[0055] As can be seen from Table 2, when the mass ratio of plant ash, crop powder, and straw powder is less than 10:15:100 (as in Table 2, the mass ratio of plant ash, crop powder, and straw powder = 7.5:15:100, 5:15:100, 2.5:15:100, 10:12.5:100, 10:10:100, 10:7.5:100 and lower ratios not listed in Table 2), less plant ash and crop powder are added, and the reaction of the materials during the fermentation process is insufficient, resulting in a decline in the performance of the prepared fermented soil. The yield increase rates of lettuce and romaine lettuce obtained from planting both decrease significantly as the mass ratio of plant ash, crop powder, and straw powder decreases. When the mass ratio of plant ash, crop powder, and straw powder is equal to 2.5 - 7.5:5 - 25:100 (as in Table 2, the mass ratio of plant ash, crop powder, and straw powder = 2.5:5:100, 5:5:100, 7.5:5:100, 2.5:15:100, 5:15:100, 7.5:15:100, 2.5:25:100, 5:25:100, 7.5:25:100), during the mixed fermentation process, cellulose and hemicellulose in the mixture are decomposed into oligosaccharides and monosaccharides, and are further utilized by the complex microorganisms to generate metabolic products such as organic acids and alcohols. At the same time, under the action of microorganisms, cellulose, hemicellulose, and lignin can gradually be transformed into humus, increasing the organic matter content of the soil and improving soil fertility. Bacillus and Actinomycetes ferment synergistically, utilizing the nutrient elements released by the hydrothermal decomposition of stabilized powder, plant ash, and camellia oleifera residue, and enzymatically decomposing the hydrothermal carbonization products of straw powder and camellia oleifera residue to form various organic acids and alcohols. And through the further synergistic nitrogen and sulfur cycle of functional microorganisms, the enrichment and resynthesis of polyphenols, vitamins, and organic acids are achieved. Under the synergistic action of the complex microorganisms, polyphenols in the aronia melanocarpa puree and seabuckthorn puree are partially degraded to generate small-molecule polyphenols with higher biological activity, thereby improving the antioxidant and antibacterial functions of the fermented soil. The complex microorganisms use the hydrothermal carbonization product of camellia oleifera residue as a carrier to adsorb, enrich, and transform the microbial metabolites, and promote the full reaction of the metabolic active substances with the active substances in the mixed probiotic pulp. The product after fermentation through the synergistic action of the complex microorganisms has a high organic matter content and rich nutrient components. The harmful substances in red mud and phosphogypsum react with the enzyme and metabolite active products to achieve transformation and effective fixation. Finally, the yield increase rate of lettuce is higher than 134% and the yield increase rate of romaine lettuce is higher than 155%.When the mass ratio of plant ash, crop powder, and straw powder is greater than 7.5:25:100 (as shown in Table 2, the mass ratio of plant ash, crop powder, and straw powder = 7.5:27.5:100, 7.5:30:100, 7.5:32.5:100, 8:25:100, 8.5:25:100, 9:25:100, and higher ratios not listed in Table 2), the addition of plant ash and crop powder is excessive, and the reaction of the materials during the fermentation process is unbalanced, resulting in a decline in the performance of the prepared fermented soil. The yield increase rates of the lettuce and lettuce obtained from planting both decrease significantly as the mass ratio of plant ash, crop powder, and straw powder further increases, and the thallium leaching concentration increases significantly as the mass ratio of plant ash, crop powder, and straw powder further increases.

[0056] Therefore, generally speaking, considering the benefits and costs, when the mass ratio of plant ash, crop powder, and straw powder is equal to 2.5 - 7.5:5 - 25:100, it is most beneficial to improve the performance of the prepared soil conditioner.

[0057] Example 3 Influence of the mass ratio of probiotic slurry, driving material powder, and stabilizing powder on the performance of the prepared soil conditioner

[0058] Mix tea seed cake residue, red mud, and phosphogypsum in a mass ratio of 30:45:100, stir evenly, and age for 36 hours to obtain the initial mixture paste residue. Place the initial mixture paste residue into a reaction kettle for hydrothermal reaction to obtain the stabilized material. Then take out the stabilized material, dry it and grind it into powder to obtain the stable powder. The liquid-solid ratio of water to the initial mixture paste residue is 5:1 mL / g, the hydrothermal temperature is 360 °C, and the hydrothermal time is 24 hours. Mix plant ash, crop powder, and straw powder in a mass ratio of 7.5:25:100, stir evenly to obtain the driving material powder, where the crop powder is sweet potato powder. Mix aronia berry puree and seabuckthorn puree in a mass ratio of 45:100, stir evenly to obtain the probiotic puree. Mix the probiotic puree, driving material powder, and stable powder in mass ratios of 0.25:20:100, 0.3:20:100, 0.4:20:100, 0.5:12.5:100, 0.5:15:100, 0.5:17.5:100, 0.5:20:100, 2.5:20:100, 4.5:20:100, 0.5:40:100, 2.5:40:100, 4.5:40:100, 0.5:60:100, 2.5:60:100, 4.5:60:100, 4.5:65:100, 4.5:70:100, 4.5:75:100, 5:60:100, 5.5:60:100, 6:60:100, stir evenly, add composite microorganisms for fermentation to obtain the fermented soil. The fermentation time is 25 days, the fermentation temperature is 50 °C. The composite microorganisms are composed of actinomycetes, bacillus, and functionalized additional bacteria. The mass ratio of the added composite microorganisms is 0.55%, and the mass ratio of actinomycetes, bacillus, and functionalized additional bacteria is 1.75:1.75:1. The actinomycetes are Cellulomonas carbonis (CGMCC 1.10786); the bacillus is Bacillus megaterium (CGMCC 1.16094); the functionalized additional bacteria are Pseudonocardia sulfidoxidans (CGMCC 4.1533).

[0059] The comparative tests of lettuce and lettuce growth rate, lettuce growth rate, preparation of heavy metal contaminated soil after remediation, heavy metal toxicity leaching test, and thallium ion concentration detection are the same as those in Example 1. The test results of this example are shown in Table 3.

[0060] Table 3 Influence of probiotic puree, driving material powder, and stable powder on the performance of the prepared soil conditioner

[0061]

[0062] As can be seen from Table 3, when the mass ratio of probiotic pulp, feed driving powder, and stabilizing powder is less than 0.5:20:100 (as in Table 3, the mass ratio of probiotic pulp, feed driving powder, and stabilizing powder = 0.4:20:100, 0.3:20:100, 0.25:20:100, 0.5:17.5:100, 0.5:15:100, 0.5:12.5:100, and lower ratios not listed in Table 3), the addition of probiotic pulp and feed driving powder is less, and the reaction of the materials during the fermentation process is insufficient, resulting in a decline in the performance of the prepared fermented soil. The yield increase rates of lettuce and leaf lettuce obtained from planting both decrease significantly as the mass ratio of probiotic pulp, feed driving powder, and stabilizing powder decreases, and the thallium leaching concentration increases significantly as the mass ratio of probiotic pulp, feed driving powder, and stabilizing powder decreases. When the mass ratio of probiotic pulp, feed driving powder, and stabilizing powder is equal to 0.5 - 4.5:20 - 60:100 (as in Table 3, the mass ratio of probiotic pulp, feed driving powder, and stabilizing powder = 0.5:20:100, 2.5:20:100, 4.5:20:100, 0.5:40:100, 2.5:40:100, 4.5:40:100, 0.5:60:100, 2.5:60:100, 4.5:60:100), during the mixed fermentation process, cellulose and hemicellulose in the mixture are decomposed into oligosaccharides and monosaccharides and are further utilized by the complex microorganisms to generate metabolic products such as organic acids and alcohols. At the same time, under the action of microorganisms, cellulose, hemicellulose, and lignin can gradually be transformed into humus, increasing the organic matter content of the soil and improving soil fertility. Bacillus and actinomycetes ferment synergistically, utilizing the nutrient elements provided by the hydrothermal decomposition of stabilizing powder, plant ash, and camellia oleifera residue to enzymatically decompose the hydrothermal carbonization products of straw powder and camellia oleifera residue to form various organic acids and alcohols, and through the further synergistic nitrogen and sulfur cycle effects of functional microorganisms, the enrichment and resynthesis of polyphenols, vitamins, and organic acids are achieved. Under the synergistic action of the complex microorganisms, polyphenols in the aronia melanocarpa pulp and seabuckthorn pulp are partially degraded to generate small-molecule polyphenols with higher biological activity, thereby improving the antioxidant and antibacterial functions of the fermented soil. The complex microorganisms use the hydrothermal carbonization product of camellia oleifera residue as a carrier to adsorb, enrich, and transform the microbial metabolic products and promote the full reaction of the metabolic active substances with the active substances in the mixed probiotic pulp. The product after fermentation through the synergistic action of the complex microorganisms has a high organic matter content and rich nutrient components, and the harmful substances in red mud and phosphogypsum react with the enzyme and metabolite products of the bacteria to achieve transformation and effective fixation. Finally, the yield increase rate of lettuce is higher than 146% and the yield increase rate of leaf lettuce is higher than 179%.When the mass ratio of probiotic pulp, feed-driving powder, and stabilizing powder is greater than 4.5:60:100 (as shown in Table 3, the mass ratio of probiotic pulp, feed-driving powder, and stabilizing powder = 4.5:65:100, 4.5:70:100, 4.5:75:100, 5:60:100, 5.5:60:100, 6:60:100 and higher ratios not listed in Table 3), the addition of probiotic pulp and feed-driving powder is excessive, and the material reaction during fermentation is unbalanced, resulting in a decline in the performance of the prepared fermentation soil. The yield increase rates of the lettuce and lettuce grown are both significantly reduced as the mass ratio of probiotic pulp, feed-driving powder, and stabilizing powder further increases, and the thallium leaching concentration increases significantly as the mass ratio of probiotic pulp, feed-driving powder, and stabilizing powder further increases.

[0063] Therefore, generally speaking, considering the benefits and costs, when the mass ratio of probiotic pulp, feed-driving powder, and stabilizing powder is equal to 0.5 - 4.5:20 - 60:100, it is most beneficial to improve the performance of the prepared soil conditioner.

[0064] Example 4 Influence of Crop Powder on the Performance of the Prepared Soil Conditioner

[0065] Mix camellia oleifera residue, red mud, and phosphogypsum according to a mass ratio of 30:45:100, stir evenly, and age for 36 hours to obtain the initial mixed paste residue. Place the initial mixed paste residue in a reaction kettle for hydrothermal reaction to obtain the stabilized material. Then take out the stabilized material, dry it and grind it into powder to obtain the stabilizing powder, where the liquid-solid ratio of water to the initial mixed paste residue is 3:1 mL / g, the hydrothermal temperature is 360 °C, and the hydrothermal time is 24 hours. Mix plant ash, crop powder, and straw powder according to a mass ratio of 7.5:25:100, stir evenly to obtain the feed-driving powder, where the crop powder is any one of corn powder, wheat powder, sweet potato powder, cassava powder, kudzu powder, oat powder, and potato powder. Mix aronia berry puree and seabuckthorn puree according to a mass ratio of 45:100, stir evenly to obtain the probiotic pulp. Mix the probiotic pulp, feed-driving powder, and stabilizing powder according to a mass ratio of 4.5:60:100, stir evenly, and add composite microorganisms for fermentation to obtain the fermentation soil, where the fermentation time is 25 days, the fermentation temperature is 50 °C, the composite microorganisms are composed of actinomycetes, bacilli, and functionalized additional bacteria, where the mass ratio of the added composite microorganisms is 0.3%, and the mass ratio of actinomycetes, bacilli, and functionalized additional bacteria is 0.25:1.75:1. The actinomycetes are Streptomyces albogriseolus (CGMCC 4.6301); the bacilli are Paenibacillus validus (CGMCC 1.12900); the functionalized additional bacteria are Comamonas phosphatis (CGMCC 1.12294). The comparative tests of lettuce and lettuce planting, the yield increase rates of lettuce and lettuce, the preparation of the heavy metal-polluted soil after remediation, the heavy metal toxicity leaching test, and the thallium ion concentration detection are the same as in Example 1. The test results of this example are shown in Table 4.

[0066] Table 4 Influence of Crop Flours on the Performance of the Prepared Soil Conditioner

[0067] Crop powder Yield increase rate of lettuce Yield increase rate of lettuce lettuce Thallium leaching concentration (mg / L) Corn flour 154.32％ 190.03％ <![CDATA[4.07×10 -3 > Wheat flour 152.67％ 187.65％ <![CDATA[4.24×10 -3 > Sweet potato flour 155.14％ 185.97％ <![CDATA[4.19×10 -3 > Cassava flour 154.25％ 190.76％ <![CDATA[4.15×10 -3 > Kudzu root powder 156.04％ 186.49％ <![CDATA[4.03×10 -3 > Oatmeal 151.93％ 189.34％ <![CDATA[4.16×10 -3 > Potato powder 153.85％ 184.52％ <![CDATA[4.09×10 -3 >

[0068] As can be seen from Table 4, when the crop flour is any one of corn flour, wheat flour, sweet potato flour, cassava flour, kudzu root flour, oat flour, and potato flour, there is no significant difference in the yield increase rate of lettuce and lettuce and the thallium leaching concentration obtained.

[0069] Example 5 Influence of Functionalized Additional Bacteria on the Performance of the Prepared Soil Conditioner

[0070] Mix camellia oil residue, red mud, and phosphogypsum in a mass ratio of 30:45:100, stir evenly, and age for 36 hours to obtain the initial mixture of paste residues. Place the initial mixture of paste residues into a reaction kettle for hydrothermal reaction to obtain a stabilized material. Then take out the stabilized material, dry it and grind it into powder to obtain a stable powder, where the liquid-solid ratio of water to the initial mixture of paste residues is 3:1 mL / g, the hydrothermal temperature is 360 °C, and the hydrothermal time is 24 hours. Mix plant ash, crop flour, and straw powder in a mass ratio of 7.5:25:100, stir evenly to obtain a driving powder, where the crop flour is potato flour. Mix aronia berry puree and seabuckthorn puree in a mass ratio of 45:100, stir evenly to obtain a probiotic puree. Mix the probiotic puree, driving powder, and stable powder in a mass ratio of 4.5:60:100, stir evenly, and add complex microorganisms for fermentation to obtain fermented soil, where the fermentation time is 25 days, the fermentation temperature is 50 °C, and the complex microorganisms are composed of actinomycetes, bacilli, and functionalized additional bacteria. The mass ratio of the added complex microorganisms is 0.3%, and the mass ratio of actinomycetes, bacilli, and functionalized additional bacteria is 1.75:0.25:1. The actinomycetes are Streptomyces badius terreus (CGMCC 4.7294); the bacilli are Virgibacillus halophilus (CGMCC 1.15481); the functionalized additional bacteria are Halomonas sulfidaeris (CGMCC 1.6324), Halorubrum sulfidigenes (CGMCC 1.6307), Pseudonocardia sulfidoxidans (CGMCC 4.1533), Burkholderia phosphaticola (CGMCC 1.12294), Bradyrhizobium diazoefficiens (CGMCC 1.15566), Flavobacterium denitrificans (CGMCC 1.12063), Azospirillum brasilense (CGMCC 1.10379), Alicycliphilus denitrificans (CGMCC 1.9074), Azotobacter beijerinckii (CGMCC 1.9044), Azotobacter vinelandii (CGMCC 1.7741), Phytobacter diazotrophicus (CGMCC 1.5339), Rhodobacter azotoformans (CGMCC 1.5023), Cellulomonas diazotrophica (CGMCC 1.1899), Azotobacter armeniacus (CGMCC 1.827), and Azotobacter chroococcum (CGMCC 1.236) any one of them.

[0071] The comparative experiment on the cultivation of lettuce and lettuce, the yield increase rate of lettuce, the yield increase rate of lettuce, the preparation of heavy metal - polluted soil after remediation, the heavy metal toxicity leaching test, and the thallium ion concentration detection are the same as those in Example 1. The test results of this example are shown in Table 5.

[0072] Table 5 Influence of functionalized additional bacteria on the performance of the prepared soil conditioner

[0073]

[0074]

[0075] As can be seen from Table 5, when the functionalized additional bacteria are any one of Halothiobacillus neapolitanus (CGMCC 1.6324), Halorhodospira halophila (CGMCC 1.6307), Pseudonocardia sulfidoxidans (CGMCC 4.1533), Comamonas phosphatis (CGMCC 1.12294), Bradyrhizobium diazoefficiens (CGMCC 1.15566), Flavobacterium denitrificans (CGMCC 1.12063), Azospirillum brasilense (CGMCC 1.10379), Alicycliphilus denitrificans (CGMCC 1.9074), Azotobacter beijerinckii (CGMCC 1.9044), Azotobacter vinelandii (CGMCC 1.7741), Phyllobacterium diazotrophicus (CGMCC 1.5339), Rhodobacter azotoformans (CGMCC 1.5023), Cellulomonas diazotrophica (CGMCC 1.1899), Azotobacter armeniacus (CGMCC 1.827) and Azotobacter chroococcum (CGMCC 1.236), there is no significant difference in the yield increase rate of lettuce and lettuce and the thallium leaching concentration.

[0076] Influence of different processes in the comparative example on the performance of the prepared soil conditioner

[0077] Process of the present invention: Mix oil-tea camellia residue, red mud, and phosphogypsum in a mass ratio of 30:45:100, stir evenly, and age for 36 hours to obtain the initial mixture paste residue. Place the initial mixture paste residue into a reaction kettle for hydrothermal reaction to obtain a stabilized material. Then take out the stabilized material, dry it and grind it into powder to obtain a stable powder, where the liquid-solid ratio of water to the initial mixture paste residue is 3:1 mL / g, the hydrothermal temperature is 360 °C, and the hydrothermal time is 24 hours. Mix plant ash, crop powder, and straw powder in a mass ratio of 7.5:25:100, stir evenly to obtain a driving material powder, where the crop powder is potato powder. Mix aronia berry raw pulp and seabuckthorn raw pulp in a mass ratio of 45:100, stir evenly to obtain a probiotic pulp. Mix the probiotic pulp, driving material powder, and stable powder in a mass ratio of 4.5:60:100, stir evenly, add composite microorganisms for fermentation to obtain fermented soil, where the fermentation time is 25 days, the fermentation temperature is 50 °C, the composite microorganisms are composed of actinomycetes, bacillus, and functionalized additional bacteria, the mass ratio of the added composite microorganisms is 0.3%, the mass ratio of actinomycetes, bacillus, and functionalized additional bacteria is 1.75:0.25:1, the actinomycetes are Streptomyces gilvosporeus (CGMCC 4.7294); the bacillus is Virgibacillus halophilus (CGMCC 1.15481); the functionalized additional bacteria are Azotobacter armeniacus (CGMCC 1.827).

[0078] Comparative process 1: Mix red mud and phosphogypsum in a mass ratio of 45:100, stir evenly, and age for 36 hours to obtain the initial paste material. Place the initial paste material into a reaction kettle for hydrothermal reaction to obtain a stabilized material. Then take out the stabilized material, dry it and grind it into powder to obtain a stable powder, where the liquid-solid ratio of water to the initial paste material is 3:1 mL / g, the hydrothermal temperature is 360 °C, and the hydrothermal time is 24 hours. Mix plant ash, crop powder, and straw powder in a mass ratio of 7.5:25:100, stir evenly to obtain a driving material powder, where the crop powder is potato powder. Mix aronia berry raw pulp and seabuckthorn raw pulp in a mass ratio of 45:100, stir evenly to obtain a probiotic pulp. Mix the probiotic pulp, driving material powder, and stable powder in a mass ratio of 4.5:60:100, stir evenly, add composite microorganisms for fermentation to obtain fermented soil, where the fermentation time is 25 days, the fermentation temperature is 50 °C, the composite microorganisms are composed of actinomycetes, bacillus, and functionalized additional bacteria, the mass ratio of the added composite microorganisms is 0.3%, the mass ratio of actinomycetes, bacillus, and functionalized additional bacteria is 1.75:0.25:1, the actinomycetes are Streptomyces gilvosporeus (CGMCC 4.7294); the bacillus is Virgibacillus halophilus (CGMCC 1.15481); the functionalized additional bacteria are Azotobacter armeniacus (CGMCC 1.827).

[0079] Comparative Process 2: Mix camellia oil residue, red mud, and phosphogypsum in a mass ratio of 30:45:100, stir evenly, and age for 36 hours to obtain the initial mixture paste residue. Place the initial mixture paste residue into a reaction kettle for hydrothermal reaction to obtain a stabilized material. Then take out the stabilized material, dry it, and grind it into powder to obtain a stable powder. The liquid-solid ratio of water to the initial mixture paste residue is 3:1 mL / g, the hydrothermal temperature is 360 °C, and the hydrothermal time is 24 hours. Mix plant ash, crop powder, and straw powder in a mass ratio of 7.5:25:100, stir evenly to obtain a driving material powder, where the crop powder is potato powder. Mix aronia berry puree, driving material powder, and stable powder in a mass ratio of 4.5:60:100, stir evenly, and add composite microorganisms for fermentation to obtain fermented soil. The fermentation time is 25 days, the fermentation temperature is 50 °C. The composite microorganisms are composed of actinomycetes, bacillus, and functionalized additional bacteria. The mass ratio of the added composite microorganisms is 0.3%. The mass ratio of actinomycetes, bacillus, and functionalized additional bacteria is 1.75:0.25:1. The actinomycetes are Streptomyces badius terreus (CGMCC 4.7294); the bacillus is Virgibacillus halophilus (CGMCC 1.15481); the functionalized additional bacteria are Azotobacter armeniacus (CGMCC 1.827).

[0080] The comparative experiments on the growth of lettuce and lettuce, the growth rate increase of lettuce and lettuce, the preparation of heavy metal-polluted soil after restoration, the heavy metal toxicity leaching test, and the thallium ion concentration detection are the same as in Example 1. The results of this comparative example are shown in Table 6.

[0081] Table 6 Influence of Different Processes on the Performance of the Prepared Soil Conditioner

[0082]

[0083] The growth rate increase of lettuce and lettuce achieved by the process of the present invention is significantly higher than that of Comparative Process 1 and Comparative Process 2, while the thallium leaching concentration achieved by the process of the present invention is significantly lower than that of Comparative Process 1 and Comparative Process 2.

Claims

1. A method for preparing a soil conditioner using phosphogypsum and red mud, characterized in that, It includes the following steps: (1) Mix camellia oleifera residue, red mud and phosphogypsum, stir evenly, age, carry out hydrothermal reaction, dry and then grind into powder to obtain stable powder; (2) Mix plant ash, crop powder and straw powder, stir evenly to obtain repellent powder; the crop powder is any one of corn powder, wheat flour, sweet potato powder, cassava powder, kudzu root powder, oat powder, potato powder; (3) Mix aronia melanocarpa original pulp and seabuckthorn original pulp, stir evenly to obtain probiotic pulp; (4) Mix probiotic pulp, repellent powder and stable powder, stir evenly, add composite microorganisms for fermentation to obtain soil conditioner; the composite microorganisms are composed of actinomycetes, bacillus and functionalized additional bacteria.

2. The method according to claim 1, wherein In step (1), the mass ratio of the camellia oleifera residue, red mud and phosphogypsum is 10 - 30:15 - 45:

100.

3. The method according to claim 1, characterized in that, In step (2), the mass ratio of the plant ash, crop powder and straw powder is 2.5 - 7.5:5 - 25:

100.

4. The method according to claim 1, wherein In step (3), the mass ratio of the aronia melanocarpa original pulp and seabuckthorn original pulp is 15 - 45:

100.

5. The method according to claim 1, wherein In step (4), the mass ratio of the probiotic pulp, repellent powder and stable powder is 0.5 - 4.5:20 - 60:

100.

6. The method according to claim 1, wherein In step (4), the actinomycetes is any one of Streptomyces microflavus lactosus, Streptomyces microflavus, Cellulomonas fimi, Streptomyces albogriseolus or Streptomyces vinaceusdrappus.

7. The method according to claim 1, wherein In step (4), the bacillus is any one of Bacillus subtilis, Bacillus licheniformis, Bacillus megaterium, Paenibacillus validus or Virgibacillus halophilus.

8. The method according to claim 1, characterized in that, In step (4), the functionalized additional bacteria is any one of Halomonas sulfidaeris, Halorubrum sulfidigenes, Pseudonocardia sulfidoxidans, Burkholderia phosphaticum, Bradyrhizobium diazoefficiens, Flavobacterium denitrificans, Azospirillum brasilense, Alicycliphilus denitrificans, Azotobacter beijerinckii, Azotobacter vinelandii, Aminobacter diazotrophicus, Rhodobacter azotoformans, Cellulomonas diazotrophica, Azotobacter armeniacus or Azotobacter chroococcum.

9. A soil conditioner prepared by the method according to any one of claims 1 - 8.

10. Use of the soil conditioner according to claim 9 in increasing plant yield or repairing heavy metal - contaminated soil.

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