Method for accelerating weathering and soil forming of waste concrete through microbial fermentation

Abstract

The invention discloses a method for accelerating weathering and soil formation of waste concrete by microbial fermentation, which comprises the following steps: crushing the waste concrete into blocks with the particle size of 20-50cm, retaining the fracture structure of the blocks, mixing the concrete blocks with biomass, adding 0.3-0.5% of compound microbial agent which specifically comprises acid-producing bacteria, cellulose degrading bacteria and silicate weathering bacteria into the mixed material, and uniformly stirring to obtain a mixture; composting the mixed material, controlling the temperature of the pile body to be 40-55 DEG C, maintaining for at least 15 days, and gradually decomposing the concrete block body by utilizing the synergistic biological weathering effect of organic acid generated by microbial metabolism and the microbial corrosion effect in the fermentation process. According to the method disclosed by the invention, the dynamic bottleneck of decomposition of calcium silicate minerals in concrete blocks is broken through by virtue of synergistic fermentation of the composite flora and the biomass and the coupling effect of organic acid release and biological erosion, and the crushing energy consumption is reduced compared with that of a traditional fine crushing process; and a novel green conversion method integrating rapid soil formation, nutrient activation and pollution prevention and control is formed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste resource utilization and microbial fermentation, and particularly relates to a method for accelerating weathering of waste concrete into soil by microbial fermentation BACKGROUND

[0002] The traditional way of disposing waste concrete is mainly landfill and simple crushing and regeneration, but there are bottlenecks such as low resource utilization rate (<30%) and long weathering period (hundreds of years under natural conditions). The stable crystal structure of calcium silicate minerals in concrete leads to extremely slow weathering rate, which directly restricts the ecological utilization of building solid waste. Although chemical acid etching method can accelerate decomposition, it has problems such as large consumption of strong acid (200-300 kg of concentrated hydrochloric acid is needed per ton), high risk of heavy metal dissolution and high treatment cost.

[0003] Bio-weathering technology is attracting attention due to its environmentally friendly characteristics. In the field of patents related to the weathering of solid waste into soil, patent CN119076589A discloses a method for the weathering of gas and phosphorus tailings into soil. First, the phosphorus tailings are made into granular fillers, and methanotrophic bacteria are loaded on the granular fillers to construct a biofilter bed with phosphorus tailings granules as the biofilm carrier and methanotrophic bacteria as the dominant microorganisms. Methane in the gas is biologically oxidized by the methanotrophic bacteria, and the methane metabolites accelerate the mineral decomposition and restructuring of the phosphorus tailings granules, releasing effective phosphorus components and obtaining weathering products. However, this method has a single microbial flora, relying only on the methanotrophic bacteria to metabolize formic acid (pKa = 3.75), which lacks sufficient acid strength and organic acid diversity to effectively decompose stable minerals such as calcium and magnesium phosphates in the phosphorus tailings. Patent CN220160895U discloses a structure for accelerating the weathering of waste soil and rock based on biomass pyrolysis. The pyrolysis of the mixed pile is achieved by heating through a heat pipe. Although this technology achieves the co-disposal of waste soil and rock and biomass, it has the following technical bottlenecks: (1) The pyrolysis process requires a high temperature of 300-500°C, which causes 40-60% of the organic matter to carbonize and be lost, significantly reducing the content of active organic matter in the product and affecting the subsequent development of plant root systems. (2) The high-temperature environment intensifies the activation of heavy metals. Actual measurement data shows that the acid-extractable proportion of cadmium (Cd) increases from 12.3% before pyrolysis to 28.5%. Patent CN110090847A discloses a method for the rapid weathering of waste rock containing sulfide minerals into soil. This method uses sulfur-oxidizing bacteria to leach or soak the waste rock containing sulfide minerals, maintaining sufficient contact between the sulfur-oxidizing bacteria and the waste rock and an oxidizing atmosphere. The sulfide minerals in the waste rock are oxidized and dissolved by the sulfur-oxidizing bacteria, causing the structural strength of the waste rock to decrease. Subsequently, the waste rock is crushed, pulverized, and sieved. The waste rock with a particle size that does not meet the standard is subjected to further biological oxidation leaching and crushing, and the waste rock particles that meet the particle size standard are considered to form coarse sand, which can be used for mine site closure and storage. Although this technology reduces the cost of obtaining soil, the action of the single sulfur-oxidizing bacteria is limited to the decomposition of sulfides, and the weathering efficiency of silicate minerals, which account for 60-80% of the waste rock, is insufficient, resulting in a sand soil with a water-holding capacity of <15% (far lower than the required 40% for plant growth). Patent CN118058163A discloses a method and system for preparing artificial soil from coal gangue and agricultural and livestock waste. The method includes: using a crushing and sieving system to produce coal gangue powder with a particle size of 150 microns or less (passing through a 100-mesh sieve); using agricultural waste such as wheat straw, distiller's grains, and livestock waste such as cow dung, combined with humic acid and effective microorganisms (EM) for biological fermentation; mixing the coal gangue powder with the humic substance in a certain proportion; and adding quicklime to adjust the pH value after mixing the coal gangue powder with the humic substance, and performing solidification and harmless treatment.However, the addition of quicklime can affect the pH of the soil, and high pH can affect the absorption of certain nutrients by plants, and can also affect the soil microbial community.

[0004] The common defects of the prior art are embodied in: the single strain has limited effect; the continuous acid production effect of biomass fermentation is not fully utilized, and the fluctuation of organic acid concentration leads to unstable weathering efficiency; most of the inorganic solid waste needs to be crushed to a smaller particle size (<2 mm), resulting in that the crushing energy consumption accounts for more than 40% of the total treatment cost; the humus produced by biomass decomposition is ignored to passivate heavy metals, and there is an environmental risk.

[0005] Therefore, it is necessary to develop a method for accelerating the weathering of waste concrete into soil by using microbial fermentation to simultaneously achieve efficient weathering of silicate minerals and stabilization of heavy metals and reduce energy consumption and cost. SUMMARY

[0006] To solve the above technical problems, the purpose of the present application is to provide a method for accelerating the weathering of waste concrete into soil by using microbial fermentation, which breaks through the limitation of traditional fine crushing process, realizes efficient decomposition of silicate minerals through organic acid produced by biomass synergistic fermentation and microbial metabolism, realizes particle size control through in-situ corrosion of microorganisms, reduces crushing energy consumption by more than 80%, and improves weathering efficiency through directional pores formed by biological erosion; the present application innovatively proposes a ternary compound microbial community of "acid-producing bacteria-cellulose degrading bacteria-silicate weathering bacteria" and a biomass synergistic fermentation system, breaks through the kinetic bottleneck of calcium silicate mineral decomposition in concrete blocks through the coupling effect of organic acid release and biological erosion, saves crushing energy consumption compared with traditional fine crushing process, and forms a new green conversion method integrating rapid soil formation, nutrient activation and pollution prevention and control.

[0007] The purpose of the present application is achieved by the following steps: (1) crushing the waste concrete to a block size of 20-50 cm, and retaining the block fissure structure; (2) mixing the concrete blocks with biomass; (3) adding 0.3%-0.5% of a compound microbial agent (based on dry mass) to the mixture, which specifically includes acid-producing bacteria, cellulose-degrading bacteria and silicate-weathering bacteria; (4) composting the mixture, controlling the pile temperature at 40-55°C for at least 15 days, and realizing aerobic fermentation through daily turning of the pile, which can be turned 2-3 times a day, utilizing the organic acids produced by microbial metabolism to synergize with biological weathering effect, and the microbial corrosion effect during the fermentation process gradually decomposes the concrete blocks; (5) finally forming a soil-like structure.

[0008] Preferably, step (1) adds 3% nano-silicon dioxide to the concrete block, and the nano-silicon dioxide has a particle size of 30 nm; the action is to serve as a microbial attachment carrier, and the high specific surface area and surface silicon hydroxyl group enhance the colonization efficiency of the bacterial population.

[0009] Preferably, step (2) is that the mass ratio of the concrete block to the biomass is 5:1.

[0010] Preferably, step (2) is that the biomass is one or more of agricultural straw, food processing waste and garden waste, and the organic matter content is greater than or equal to 35%, and the carbon-nitrogen ratio is controlled to be 25-30:1.

[0011] Preferably, step (3) is that the acid-producing bacteria are Lactobacillus acidophilus, the cellulose-degrading bacteria are cellulose-degrading bacteria Aspergillus niger, and the silicate weathering bacteria are silicate weathering bacteria Bacillus, and the effective viable bacterial number ratio of the Lactobacillus acidophilus, the cellulose-degrading bacteria Aspergillus niger and the silicate weathering bacteria Bacillus is 1:2:1.

[0012] Preferably, step (3) is that the microorganisms are activated before the addition of the compound microbial agent, and the activation is specifically carried out by using a phosphate buffer solution with a pH of 6.8 and containing 2% sucane for 30 min, and after the activation, the bacterial concentration is increased by 3-5 times.

[0013] Preferably, step (4) is that during the fermentation process, lactic acid and acetic acid generated by the acid-producing bacteria gradually reduce the pH of the system to 4.5-5.8, and in combination with the exopolysaccharide secretion of the silicate weathering bacteria, the decomposition of CaSiO3 in the concrete is jointly promoted.

[0014] Preferably, step (4) is that during the fermentation process, humus-silicon calcium composite colloids are synchronously formed, so that the cation exchange capacity of the product is 25-30 cmol(+) / kg, and the organic matter content is greater than or equal to 12%.

[0015] Preferably, step (4) is that at the end of the fermentation, 2% sodium alginate solution based on the dry mass of the mixture is added for granulation, a three-dimensional network agglomerate structure is formed through calcium ion crosslinking, and the mechanical stability, heavy metal chelating capacity and nutrient slow-release performance of the product are simultaneously improved.

[0016] Preferably, step (5) is that the particle size of the soil-like structure is less than or equal to 5 mm, the porosity is 40%-45%, and the calcium-silicon ratio is 1.2-1.5:1.

[0017] The principle of the application is as follows: Collaborative fermentation of waste concrete and biomass waste, using organic acids produced by microbial metabolism and biological erosion to accelerate the decomposition of silicate minerals, to realize the rapid weathering of concrete into soil; the core principle lies in the construction of a multi-strain collaborative system of acid-producing bacteria, cellulose-degrading bacteria and silicate weathering bacteria, breaking through the mineral weathering kinetics limit through the cascade effect of metabolic products; The crack system (width 0.1mm~0.5mm) of the large concrete provides a natural channel for microbial colonization, and the acid-producing bacteria form a biofilm along the crack wall, expanding the crack network by continuous acid production. This process produces two size effects: ① crack expansion makes the block self-break, and the specific surface area increases continuously; ② the exposure of more active sites of calcium silicate on the new fracture surface greatly improves the weathering efficiency. The microbial flora presents a phased collaborative feature during the fermentation process: the acid-producing bacteria dominate the decomposition of organic matter and release organic acids such as lactic acid and acetic acid, forming an acidic environment to promote the protonation and dissolution of the calcium silicate mineral surface; cellulose-degrading bacteria continuously decompose lignocellulose in biomass to provide a stable carbon source and secondary metabolites for the system; silicate weathering bacteria secrete extracellular polysaccharides and iron carriers to implement biological erosion on the mineral lattice, further dissociating the silicate structure. The three work together to significantly improve the mineral decomposition efficiency; The synergistic effect of organic acids and microorganisms induces the formation of a honeycomb pore structure on the surface of concrete particles, optimizing the calcium-silicon ratio and surface properties of the particles, making them have a physical structure similar to natural soil; the dissolved calcium ions combine with humus to form organic-inorganic composite colloids, not only improving the cation exchange capacity of the product, but also stabilizing heavy metal ions through complexation, simultaneously achieving the slow release of nutrient ions and the in-situ passivation of pollutants; the humus produced during the fermentation process and the mineral skeleton together build a three-dimensional network structure that is water-retaining and air-permeable, providing a suitable environment for plant root development; This system ensures environmental safety through three mechanisms: the functional groups of humus form stable chelates with heavy metal ions; the metabolic products of silicate weathering bacteria promote the transformation of heavy metals; and the physical adsorption of the porous structure limits the migration of pollutants. The final product can be directly used for ecological restoration engineering, and its self-sustaining nutrient cycling characteristics support plant growth without the need for external addition of chemical fertilizers, providing an efficient and low-cost biological conversion path for the resource utilization of construction waste.

[0018] The beneficial effects of the present application are: 1. Through the synergistic effect of acid-producing bacteria, cellulose-degrading bacteria and silicate weathering bacteria; acid-producing bacteria continuously release organic acids such as lactic acid and acetic acid to dissolve calcium silicate minerals; cellulose-degrading bacteria decompose biomass to provide carbon sources and maintain microbial activity; silicate weathering bacteria strengthen the mineral erosion effect through extracellular polysaccharide secretion and biofilm formation; the three work together to shorten the concrete weathering period from hundreds of years under natural conditions to a few months, and significantly improve the decomposition rate of calcium silicate; 2. During fermentation, humic substances combine with calcium and magnesium ions dissolved from minerals to form organic-inorganic complex colloids, which efficiently complex and fix heavy metal ions (such as Pb²⁺ and Cd²⁺) through functional groups such as carboxyl and phenolic hydroxyl groups; at the same time, silicate weathering bacteria reduce Cr(VI) to the low-toxicity Cr(III) through metabolism, and combined with the silicate precipitation and encapsulation effect, the concentration of heavy metal leaching is reduced, meeting the national hazardous waste identification standards. 3. The humus produced by biomass decomposition combines with mineral dissolved ions to form a slow-release nutrient pool, which can provide nitrogen, phosphorus, potassium and trace elements required for plant growth in a long-term and stable manner; the honeycomb-like pores (porosity 40%~45%) formed on the surface of concrete particles and humus synergistically improve the water retention of the material, while optimizing the calcium-silicon ratio (1.2~1.5:1), so that the product has the water permeability and fertilizer retention of natural soil. 4. Utilizing biomass fermentation to produce acid to replace traditional chemical acid etching processes avoids the consumption of strong acids and simultaneously achieves biomass reduction and a construction solid waste conversion rate of >60%; the products can be directly used in slope greening, mine restoration and other scenarios without secondary processing; when planting plants such as ryegrass, the root development speed is higher than that of natural soil, and no external fertilizer is required; 5. By regulating pH and nutrient release in situ through microbial metabolism, secondary pollution introduced by chemical additives is avoided; the stable organic-mineral complex in the product can fix carbon for a long time, reducing greenhouse gas emissions; this technology provides an integrated solution of "weathering-soil formation-remediation" for the resource utilization of construction solid waste, promoting the green transformation of urban solid waste into ecological materials. 6. Using 20cm~50cm blocks to replace the traditional fine crushing process, the fissure network of the blocks forms a natural microbial reactor: saving crushing energy consumption and reducing processing costs; microorganisms grow directionally along the fissures to form bio-erosion channels, which gradually increases the effective reaction area; the fresh cross-sections generated by the autonomous crushing of the blocks continuously expose the highly active mineral surface, improving the weathering rate in the later stage of fermentation. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0020] Example 1 This embodiment utilizes microbial fermentation to accelerate the weathering of waste concrete into soil, including the following steps: (1) Use a jaw crusher to crush waste concrete of C30 strength grade into blocks with a particle size of 20cm~50cm, retain the crack structure of the blocks, and remove steel reinforcement impurities by magnetic separation; (2) Mix concrete blocks and biomass at a mass ratio of 5:1, i.e., 500 kg of concrete and 100 kg of biomass, and layer them into the fermentation tank; the biomass is made of rice straw (67% organic matter content) and corn cobs at a mass ratio of 3:1, and is chopped into 2cm~3cm pieces and the moisture content is adjusted to 55%; (3) Take 3 kg of compound microbial agent (live bacteria of Lactobacillus acidogenae, Aspergillus niger and Bacillus silicate weathering in a ratio of 1:2:1) and add it to phosphate buffer (pH 6.8) containing 2% sucrose. Shake and activate at 35°C for 30 min. Spray the activated compound microbial agent into the mixture. (4) The mixture is composted with a pile size of 3m×1.5m×1.2m. The pile temperature is controlled at 45℃~55℃ and fermented for 18 days (heating period (0 days~3 days), high temperature period (4 days~12 days), and decomposition period (13 days~18 days)). The pile is turned twice a day to maintain an oxygen concentration of >15%. The organic acids produced by microbial metabolism work together with biological weathering. During the fermentation process, the microbial corrosion causes the concrete blocks to decompose gradually. (5) After fermentation, the material is screened through a 5mm sieve and finally forms a soil-like structure. The material on the sieve is returned to the secondary fermentation. Performance testing showed that XRD revealed a decrease in the intensity of the characteristic peak of calcium silicate (2θ=29.4°), SEM observation revealed the formation of pits with a depth of 50-80 μm on the concrete surface, the product porosity reached 42%, the calcium-silicon ratio was optimized to 1.3:1, the cation exchange capacity (CEC) was increased to 28 cmol(+) / kg, and the Pb and Cd leaching concentrations were 0.15 mg / L and 0.03 mg / L, respectively, meeting the GB5085.3-2007 standard.

[0021] Example 2 This embodiment utilizes microbial fermentation to accelerate the weathering of waste concrete into soil, which differs from Embodiment 1 in that: Step (2) 1000kg of concrete and 200kg of biomass, of which the biomass is soybean residue (75% moisture content) dehydrated to 55% moisture content by a screw filter press, and coffee grounds and fruit and vegetable residues (apple peels, carrot tailings) are processed into ≤5mm particles by a shredder. Soybean residue, coffee grounds and fruit and vegetable residues are mixed in a mass ratio of 2:1:1, and urea is added to adjust the C / N ratio to 28:1. Step (3) Take 5.5 kg of compound microbial agent (calculated as 0.5% of the dry basis of the mixture), in which the effective live bacteria ratio of Lactobacillus acidogenae, Aspergillus niger and Bacillus silicate weathering is 1:2:1, add it to phosphate buffer (pH 6.8) containing 2% sucrose, shake and activate at 35℃ for 30 min and then spray it. Step (4) Stack size: 4m×2m×1.5m; During fermentation, add 50kg of soybean residue on the 5th day (spread evenly by an automatic spreader). When the pH sensor detects pH<4.5, spray calcium carbonate powder (10% suspension, 0.5kg / m³). Cover with a three-layer insulation film (inner PE breathable film + middle aluminum foil reflective layer + outer PVC waterproof film) to maintain the core temperature at 50±2℃. Use a laser particle size analyzer for online monitoring. On the 15th day, 50% of the lumps decompose to ≤10cm, and on the 25th day, 90% of the particles are ≤5mm. Performance testing showed that the peak concentration of lactic acid reached 12 mmol / L, oxalic acid 8.5 mmol / L (HPLC detection), the effective phosphorus content increased from 0.06% to 0.41%, and the potassium slow-release period was extended. When tall fescue was planted using the soil-like material obtained in this embodiment, the root biomass reached 4.2 g / plant after 30 days (compared to 2.8 g / plant in natural soil).

[0022] Example 3 This embodiment utilizes microbial fermentation to accelerate the weathering of waste concrete into soil, which differs from Embodiment 1 in that: Step (1) Eddy current separation removes impurities from concrete blocks, followed by the addition of 3% by mass of nano-silica (30nm particle size) to enhance microbial adhesion; The biomass in step (2) is specifically processed by using a hammer mill to process the sycamore leaves into ≤1cm fragments, drying them at 60℃ to a moisture content of 15%, crushing pine branches to pass through a 5mm sieve, and exposing the lawn mower to sunlight for 48 hours to sterilize them. The sycamore leaves, pine branches, and lawn mower are mixed in a ratio of 4:3:3, and the C / N ratio is adjusted to 26:1. Step (4) Before fermentation, a 10cm thick polyurethane insulation layer is set at the edge of the pile, and 5 sets of PT100 temperature sensors are arranged (one set in the center and one set at each of the four corners); during fermentation, if the temperature difference is >8℃, the lateral blower is started; during fermentation, on the 7th day, the silicate weathering Bacillus bacterial solution is added by high pressure injection gun, with an injection depth of 30cm and a grid spacing of 50cm, and a total inoculation amount of 2L / m³; at the end of fermentation, sodium alginate solution accounting for 2% of the dry basis mass of the mixture is added, granulated, and 1mm~3mm aggregates are formed; Tests showed that a large amount of calcium silicate was decomposed within 20 days of fermentation, and the organic matter content was 12%.

[0023] Example 4 This embodiment utilizes microbial fermentation to accelerate the weathering of waste concrete into soil, which differs from Embodiment 1 in that: Step (2) The biomass is sugarcane bagasse drum dried to a moisture content of 40%, crushed and passed through a 3mm sieve, and 2% soybean meal is added to adjust the C / N ratio to 28:1; Step (3) Add 0.45% compound microbial agent (by dry weight), i.e., 5.0 kg (of which the effective live bacteria ratio of Lactobacillus acidogenae, Aspergillus niger and Bacillus silicate weathering is 1:2:1), and spray the agent after activation with phosphate buffer (pH 6.8) containing 2% sucrose; Step (4) Fermentation is a two-stage fermentation. Stage 1 (0 days to 5 days): temperature controlled at 50℃, turning the pile 3 times a day; on the 6th day, 10% fresh sugarcane bagasse is added, and the temperature is controlled at 45℃ from the 6th to the 15th day. Using a laser particle size analyzer for online monitoring, 50% of the block particles decomposed to ≤10cm on day 15, and 90% of the particles were ≤5mm on day 25. Performance testing showed that the concrete conversion rate was improved (XRD-RIR method), and the peak organic acid concentrations were: lactic acid 13.6 mmol / L and citric acid 7.2 mmol / L (ion chromatography). The treatment cost was 145 yuan / ton, which is 61% lower than that of the chemical method. After 6 months, the porosity retention rate was >60%.

Claims

1. A method for accelerating the weathering of waste concrete into soil using microbial fermentation, characterized in that... Includes the following steps: (1) Crush the waste concrete into blocks with a particle size of 20cm~50cm, while preserving the crack structure of the blocks; (2) Mix the concrete blocks with biomass; (3) Add 0.3%~0.5% compound microbial agent to the mixture, specifically including acid-producing bacteria, cellulose-degrading bacteria and silicate weathering bacteria; (4) Compost the mixture and control the temperature of the pile to 40℃~55℃ for at least 15 days. Aerobic fermentation is achieved by turning the pile daily. The organic acids produced by microbial metabolism work together with biological weathering. During the fermentation process, the microbial corrosion causes the concrete blocks to decompose gradually. (5) Eventually, a soil-like structure is formed.

2. The method for accelerating the weathering of waste concrete into soil using microbial fermentation according to claim 1, characterized in that... Step (1) Add 3% nano silica to the concrete block. The nano silica has a particle size of 30 nm.

3. The method for accelerating the weathering of waste concrete into soil using microbial fermentation according to claim 1, characterized in that... Step (2) The mass ratio of concrete blocks to biomass is 5:

1.

4. The method for accelerating the weathering of waste concrete into soil using microbial fermentation according to claim 1, characterized in that... The biomass mentioned in step (2) is one or more of agricultural straw, food processing waste, and garden waste, and the organic matter content is ≥35%, and the carbon-nitrogen ratio is controlled at 25~30:

1.

5. The method for accelerating the weathering of waste concrete into soil using microbial fermentation according to claim 1, characterized in that... The acid-producing bacteria in step (3) are Lactobacillus acidogenae, the cellulose-degrading bacteria are Aspergillus niger, and the silicate weathering bacteria are Bacillus spp. The effective live bacteria ratio of Lactobacillus acidogenae, Aspergillus niger, and Bacillus spp. is 1:2:

1.

6. The method for accelerating the weathering of waste concrete into soil using microbial fermentation according to claim 1, characterized in that... Step (3) Before adding the compound microbial agent, microbial activation is performed, specifically by activating with a phosphate buffer solution containing 2% sucrose at pH 6.8 for 30 minutes.

7. The method for accelerating the weathering of waste concrete into soil using microbial fermentation according to claim 1, characterized in that... In step (4), the pH of the system gradually decreases to 4.5-5.8 during the fermentation process.

8. The method for accelerating the weathering of waste concrete into soil using microbial fermentation according to claim 1, characterized in that... In step (4), the cation exchange capacity of the product during fermentation is between 25 cmol(+) / kg and 30 cmol(+) / kg.

9. The method for accelerating the weathering of waste concrete into soil using microbial fermentation according to claim 1, characterized in that... Step (4) Add sodium alginate solution at 2% of the dry weight of the mixture at the end of fermentation for granulation.

10. The method for accelerating the weathering of waste concrete into soil using microbial fermentation according to claim 1, characterized in that... Step (5) The soil-like structure has a particle size ≤ 5 mm, porosity 40%~45%, and calcium-silicon ratio 1.2~1.5:1.