Nutrient substrate using high-alkaline low-organic matter engineering spoil and preparation method thereof

Abstract

This invention provides a nutrient matrix using highly alkaline, low-organic-matter construction waste and its preparation method, belonging to the field of nutrient matrix technology. The nutrient matrix comprises the following raw materials by weight percentage: 55%–60% construction waste, 25%–35% peat, 0.5%–1.0% microbial inoculant, and 3%–5% vermiculite; the nutrient matrix also includes earthworms. The preparation method is as follows: the construction waste is crushed and sieved to remove large gravel and construction debris, obtaining the matrix base material. This material is then mixed evenly with peat, vermiculite, and microbial inoculant, and inoculated with earthworms to obtain the nutrient matrix. This invention, through the scientific compounding of construction waste, low-proportion peat, microbial inoculant, and vermiculite, combined with earthworm bio-enrichment technology, utilizes the ingestion, digestion, and excretion of earthworms and the fermentation of the inoculant to rapidly reduce the pH value of the construction waste, significantly increase the organic matter content and soil enzyme activity, and form an excellent granular structure. This nutrient matrix has broad applicability and environmental safety.

Description

Technical Field

[0001] This invention belongs to the field of nutrient substrate technology, and particularly relates to a nutrient substrate using highly alkaline, low-organic-matter engineering waste soil and its preparation method. Background Technology

[0002] With the acceleration of urbanization and the continuous expansion of infrastructure construction in my country, various construction projects have generated a huge amount of construction waste. This waste is generally characterized by high alkalinity, low organic matter content, compact structure, and poor aggregate structure, making it unsuitable for direct use in agricultural production, land reclamation, or landscaping. Currently, construction waste is mostly disposed of in open-air dumps or simple landfills, which not only occupies a large amount of land resources but also easily causes environmental problems such as dust pollution and soil erosion. The resource utilization rate is low, and the pressure of disposal is significant.

[0003] Existing technologies have attempted to use construction waste as raw materials for building materials such as brick making and roadbed filling, or as a soil amendment substrate for preparing planting soil. However, the former has high requirements for the composition and properties of the waste and has a limited capacity for disposal, making it difficult to handle large quantities of waste. The latter is constrained by high alkalinity and low organic matter content, and direct application will inhibit plant nutrient absorption, resulting in poor fertility and poor water and fertilizer retention capacity. Existing methods for improving construction waste soil are mainly divided into physical, chemical, and organic methods. Physical methods improve aeration and permeability by adding river sand, perlite, vermiculite, etc., but cannot enhance nutrients and biological activity. Chemical methods often use acidic substances such as sulfur and ferrous sulfate to neutralize alkalinity, which can easily introduce salt, cause soil compaction, or leave chemical residues. Organic methods often supplement organic matter and nutrients by compounding peat, compost, and commercial organic fertilizers. Some technologies use a simple compounding mode of construction waste soil and peat, which has some effect but has obvious limitations. In order to achieve the effects of reducing alkalinity and supplementing fertilizer, the proportion of peat added is usually high. However, peat is a non-renewable resource, and over-exploitation will damage wetland ecosystems, and it is costly and unsustainable. At the same time, simple physical mixing or simple organic addition is difficult to quickly reconstruct soil microbial and animal communities, and the recovery of soil enzyme activity is slow, making it difficult to form a good water-stable aggregate structure. Traditional organic materials have limited effects on improving highly alkaline construction waste soil and often need to be combined with a large amount of acid regulators, which further increases costs.

[0004] In summary, existing soil improvement technologies suffer from problems such as high peat consumption, poor alkalinity reduction, slow improvement of soil biological activity, high improvement costs, and uneven and unsustainable effects. These limitations hinder the synergistic, efficient, and low-cost improvement of the pH, nutrient status, and physical structure of construction waste soil, severely restricting its large-scale resource utilization. Therefore, researching a technology to transform highly alkaline, low-organic-matter construction waste soil into a nutrient substrate with excellent physicochemical properties that can be directly used for seedling cultivation or landscaping is of significant practical importance and application value for promoting the resource utilization of construction waste, developing a circular economy, and alleviating the shortage of high-quality soil resources. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides a nutrient matrix utilizing highly alkaline, low-organic-matter engineering waste soil and its preparation method. This invention employs a scientific blend of engineering waste soil, a low proportion of peat, microbial agents, and vermiculite, combined with earthworm bio-enrichment technology. Utilizing the ingestion, digestion, and excretion of earthworms, along with the synergistic fermentation of microbial agents, it can rapidly reduce the pH value of the waste soil, significantly increase organic matter content and soil enzyme activity, and form an excellent granular structure.

[0006] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of the present invention: This invention provides a nutrient matrix utilizing highly alkaline, low-organic-matter engineering waste soil, comprising the following raw materials by weight percentage: 55%–60% engineering waste soil, 25%–35% peat, 0.5%–1.0% microbial inoculant, and 3%–5% vermiculite; The nutrient substrate also includes earthworms.

[0007] Furthermore, the nutrient matrix comprises the following raw materials by weight percentage: 60% engineering waste soil, 35% peat, 0.5% microbial inoculant, and 4.5% vermiculite; The nutrient substrate also includes earthworms.

[0008] Furthermore, the engineering waste soil has a pH > 8.5, an organic matter content of 8.5–15 g / kg, a available potassium content of 560 mg / kg, an alkaline available nitrogen content of 53.05 mg / kg, an available phosphorus content of 65.34 mg / kg, and an electrical conductivity of 244 μS / cm.

[0009] Furthermore, the peat has a particle size of 0–5 mm; The vermiculite has a particle size of 1–3 mm.

[0010] Furthermore, the earthworm addition amount is 3 earthworms per 1 kg of the nutrient substrate.

[0011] Furthermore, the earthworm is preferably the Eisenia fetida.

[0012] The second technical solution of the present invention: The present invention also provides a method for preparing the nutrient matrix of the high alkalinity and low organic matter engineering waste soil, comprising the following steps: After crushing and sieving the construction waste, large gravel and construction debris are removed to obtain the matrix base material. The matrix base material, peat, vermiculite and microbial agent are mixed evenly and then inoculated with earthworms to obtain the nutrient matrix.

[0013] Furthermore, the particle size of the engineering waste soil after crushing and sieving is <10 mm.

[0014] Furthermore, the particle size of the crushed and sieved engineering waste is preferably <5 mm.

[0015] Furthermore, after inoculating earthworms, they are cultured for 40 to 50 days at a moisture content of 60% to 75% and a culture temperature of 15 to 30°C.

[0016] Furthermore, after inoculating earthworms, they were cultured for 45 days at a moisture content of 60%–75% and a culture temperature of 15–30 ℃.

[0017] The beneficial effects of this invention compared to the prior art are as follows: This invention achieves deep resource utilization by turning waste into treasure, breaking through the bottleneck of construction waste disposal and utilization: existing technologies mostly use construction waste as backfill material or directly landfill it, which not only occupies land but also easily causes secondary pollution. This invention, by introducing a specific biological-physicochemical synergistic improvement mechanism, completely changes the inert structure of construction waste. Utilizing the combined action of earthworms and microorganisms, this invention transforms the inert minerals and added organic materials in the construction waste into active nutrients that plants can utilize, successfully converting originally unusable waste construction waste into a high-quality cultivation substrate that meets agricultural and landscaping standards, greatly expanding the avenues for high-value utilization of solid waste.

[0018] This invention offers high efficiency and significantly shortens the maturation cycle: Traditional soil improvement or composting techniques typically require months or even more than six months of natural weathering or static stockpiling, resulting in low efficiency. The microbial-earthworm dual-effect bioreactor constructed in this invention utilizes the metabolic activities of organisms to generate heat and enzymes, accelerating the mineralization and humification of organic matter. This method can complete the rapid maturation and dealkalization of slag within 45 days, reducing time costs by more than 60% compared to traditional natural aging methods, and significantly improving production efficiency.

[0019] The nutrient substrate developed in this invention exhibits superior performance, broad applicability, and environmental safety. The nutrient substrate prepared by this invention not only meets or exceeds commercially available peat substrates in terms of physicochemical indicators (bulk weight, pH value), but also demonstrates excellent biological activity. Because this invention employs a biological method to reduce alkalinity rather than chemical acidification, it avoids the potential damage to plant roots from chemical residues, and the product is odorless and free of pathogens. This nutrient substrate is suitable for vegetable seedling cultivation, flower planting, urban rooftop greening, and soil improvement, possessing good environmental compatibility and promising market prospects.

[0020] The preparation method of this invention is green and environmentally friendly, in line with the concept of sustainable development: the entire process produces no wastewater or exhaust gas emissions, belonging to clean production technology. By reducing peat mining, it protects wetland ecosystems while simultaneously disposing of urban construction waste, achieving a circular economy model of treating waste with waste. This technology operates under mild conditions, requires no high-temperature or high-pressure equipment, and has low energy consumption, aligning with current green and low-carbon development trends. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The above is a bar chart showing the soil bulk density of the nutrient substrates prepared in Example 1 and Comparative Examples 1-6 of this invention. Figure 2 The bar chart shows the seed germination rate in the nutrient substrates prepared in Example 1 and Comparative Examples 1-6 of this invention. Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0024] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0026] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0027] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0028] The microbial agents described in the following embodiments and comparative examples of this invention were purchased from Weifang Jinong Biotechnology Co., Ltd., with an effective live bacteria count of 200 million CFU / g. The Mumei Tuli microbial community is composed of 61 kinds of beneficial bacteria, mainly including actinomycetes, decomposing bacteria, Bacillus subtilis and other functional bacteria.

[0029] Example 1 A nutrient matrix utilizing highly alkaline, low-organic-matter construction waste soil comprises the following raw materials: 3.0 kg of construction waste soil, 1.75 kg of peat, 0.025 kg of microbial inoculant, 0.225 kg of vermiculite, and 15 Eisenia fetida earthworms.

[0030] The above-mentioned method for preparing a nutrient matrix using highly alkaline, low-organic-matter engineering waste soil includes the following steps: The engineering waste soil was crushed and sieved to a particle size of <5 mm to remove large gravel and construction waste, thus obtaining the matrix base material. The matrix base material was then mixed evenly with peat, vermiculite and microbial inoculant, and 15 Eisenia fetidae earthworms were inoculated. Water was sprayed regularly to maintain a moisture content of 60% to 75%, and the mixture was cultured at 25 ℃ for 45 days to obtain the nutrient substrate (T3).

[0031] Comparative Example 1 A nutrient substrate utilizing highly alkaline, low-organic-matter construction waste soil, using 5 kg of construction waste soil and 15 Eisenia fetida earthworms as raw materials.

[0032] The above-mentioned method for preparing a nutrient matrix using highly alkaline, low-organic-matter engineering waste soil includes the following steps: The engineering waste soil is crushed and sieved to a particle size of <5 mm to remove large gravel and construction waste, thus obtaining the matrix base material. Then, 15 Eisenia fetidae earthworms are inoculated, and water is sprayed regularly to maintain a moisture content of 60% to 75%. The substrate is cultured at 25 ℃ for 45 days to obtain the nutrient substrate (T0).

[0033] Comparative Example 2 A nutrient matrix utilizing highly alkaline, low-organic-matter construction waste soil comprises the following raw materials: 4.5 kg of construction waste soil, 0.25 kg of peat, 0.025 kg of microbial inoculant, 0.225 kg of vermiculite, and 15 Eisenia fetida earthworms.

[0034] The preparation method is the same as in Example 1, and the nutrient substrate (T1) is obtained.

[0035] Comparative Example 3 A nutrient matrix utilizing highly alkaline, low-organic-matter construction waste soil comprises the following raw materials: 3.75 kg of construction waste soil, 1.0 kg of peat, 0.025 kg of microbial inoculant, 0.225 kg of vermiculite, and 15 Eisenia fetida earthworms.

[0036] The preparation method is the same as in Example 1, and the nutrient matrix (T2) is obtained.

[0037] Comparative Example 4 A nutrient matrix utilizing highly alkaline, low-organic-matter construction waste soil comprises the following raw materials: 4.5 kg of construction waste soil, 0.25 kg of mushroom residue, 0.025 kg of microbial inoculant, 0.225 kg of vermiculite, and 15 Eisenia fetida earthworms.

[0038] The preparation method is the same as in Example 1, and the nutrient matrix (T4) is obtained.

[0039] Comparative Example 5 A nutrient matrix utilizing highly alkaline, low-organic-matter construction waste soil comprises the following raw materials: 3.75 kg of construction waste soil, 1.0 kg of mushroom residue, 0.025 kg of microbial inoculant, 0.225 kg of vermiculite, and 15 Eisenia fetida earthworms.

[0040] The preparation method is the same as in Example 1, and the nutrient matrix (T5) is obtained.

[0041] Comparative Example 6 A nutrient matrix utilizing highly alkaline, low-organic-matter construction waste soil comprises the following raw materials: 3.0 kg of construction waste soil, 1.75 kg of mushroom residue, 0.025 kg of microbial inoculant, 0.225 kg of vermiculite, and 15 Eisenia fetida earthworms.

[0042] The preparation method is the same as in Example 1, and the nutrient substrate (T6) is obtained.

[0043] Performance testing The chemical, physical, biological, and safety properties of the nutrient substrates prepared in Example 1 and Comparative Examples 1-3 were tested, and the testing standards for each property are shown in Table 1.

[0044] Table 1

[0045] The physicochemical properties of the nutrient matrices prepared in Example 1 and Comparative Examples 1-6 are shown in Table 2, the enzyme activity test results are shown in Table 3, and the aggregate structure test results of the nutrient matrices are shown in Table 4 (Example 1 and Comparative Examples 1-3). Two parallel experiments were performed for each treatment group, and the average value of the test results was taken.

[0046] Table 2 Physicochemical Properties

[0047] As shown in Table 2, with the increase of peat addition ratio, the pH value of the nutrient substrate decreased, the content of organic matter, available potassium, and alkaline nitrogen increased, the available phosphorus did not change significantly, the conductivity showed an increasing trend, and the cation exchange capacity increased. The organic matter content in the T3 treatment group reached 225.90 g / kg, which met the requirements of the nutrient substrate.

[0048] Compared with the T3 treatment group, the pH of the mushroom residue treatment groups T4 to T6 was relatively high and the organic matter content was low, which could not meet the requirements of the nutrient substrate.

[0049] Table 3 Enzyme Activities

[0050] As shown in Table 3, with the increase of peat addition ratio, the urease activity, acid phosphatase activity and amylase activity of the nutrient matrix increase, which can accelerate the decomposition and transformation of nitrogen, phosphorus and carbohydrates in the matrix, promote the mineralization and release of nutrients, improve nutrient utilization, improve the nutrient supply level of the matrix, and facilitate the metabolic accumulation of active substances in the material.

[0051] Table 4 Aggregate Structure

[0052] As shown in Table 4, with the optimization of treatment conditions, the proportion of water-stable aggregates and large aggregates in the samples continued to increase overall, while the proportion of fine particles decreased significantly. Among them, treatment T0 had the worst aggregate structure and the highest proportion of fine particles; treatments T1 and T2 showed some improvement in aggregate structure, reaching a moderate level; treatment T3 significantly increased the proportion of water-stable aggregates and large aggregates, significantly reduced the proportion of fine particles, and had the best matrix aggregate structure, resulting in an excellent overall structural evaluation.

[0053] The safety indicators of the nutrient substrates prepared in Example 1 and Comparative Examples 1-6 were tested, and the results are shown in Table 5.

[0054] Table 5

[0055] As can be seen from Table 5, the nutrient substrate (T3 treatment group) prepared by this invention meets the requirements of GB33891-2017 for organic substrates for greening, that is, it meets the requirements of Class I substrates with total cadmium ≤1.5 mg / kg, total mercury ≤1.0 mg / kg, total lead ≤120 mg / kg, total chromium ≤60 mg / kg, and total arsenic ≤10 mg / kg.

[0056] The soil bulk density of the nutrient substrates prepared in Example 1 and Comparative Examples 1-6 was tested, and the test results are as follows: Figure 1 As shown, through Figure 1 It can be seen that the soil bulk density range of high-quality substrate is 0.2–0.8 g / cm³. 3 The soil bulk density in treatment groups T2 and T3 were 0.7 and 0.53 g / cm³, respectively. 3 Compared with the control group (1.26 g / cm³), 3 The bulk density of the T3 treatment group decreased by 44.4% and 58.0%, respectively. The bulk density of the T3 treatment group met the standard of vegetable seedling substrate (NY / T2118-2012) (0.2~0.6 g / cm³). 3 ) Chinese cabbage was planted in the nutrient substrates prepared in Example 1 and Comparative Examples 1-6, and the germination rate was as follows: Figure 2 As shown, through Figure 2 It can be seen that the germination rate of T0 was 33.33%, T1 was 44.44%, T2 was 66.67%, and T3 was 88.89%. The seed germination rates of the T2 and T3 treatment groups were significantly higher than those of the T0 treatment group.

[0057] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A nutrient matrix utilizing highly alkaline, low-organic-matter engineering waste soil, characterized in that, The raw materials include the following weight percentages: 55%–60% construction waste, 25%–35% peat, 0.5%–1.0% microbial inoculant, and 3%–5% vermiculite; The nutrient substrate also includes earthworms.

2. The nutrient matrix using highly alkaline, low-organic-matter engineering waste soil according to claim 1, characterized in that, The engineering waste soil has a pH > 8.5, an organic matter content of 8.5–15 g / kg, available potassium of 560 mg / kg, available nitrogen of 53.05 mg / kg, available phosphorus of 65.34 mg / kg, and an electrical conductivity of 244 μS / cm.

3. The nutrient matrix using highly alkaline, low-organic-matter engineering waste soil according to claim 1, characterized in that, The peat has a particle size of 0–5 mm; The vermiculite has a particle size of 1–3 mm.

4. The nutrient matrix using highly alkaline, low-organic-matter engineering waste soil according to claim 1, characterized in that, The earthworms are added at a rate of 3 earthworms per 1 kg of the nutrient substrate.

5. A method for preparing a nutrient matrix for highly alkaline, low-organic-matter engineering waste soil as described in any one of claims 1 to 4, characterized in that, Includes the following steps: After crushing and sieving the construction waste, large gravel and construction debris are removed to obtain the matrix base material. The matrix base material, peat, vermiculite and microbial agent are mixed evenly and then inoculated with earthworms to obtain the nutrient matrix.

6. The preparation method according to claim 5, characterized in that, The particle size of the engineering waste soil after crushing and sieving is <10 mm.

7. The preparation method according to claim 5, characterized in that, After inoculating earthworms, culture them for 40 to 50 days at a moisture content of 60% to 75% and a culture temperature of 15 to 30 ℃.

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