Methods for the Agricultural Resource Utilization of Construction Waste

Abstract

The application relates to a construction slag farmland resource utilization method, which comprises the following steps: 1) dry treatment and air drying of the slag: obtaining air-dried construction slag; 2) garden waste composting: obtaining a garden waste compost product; 3) preparation of a composite improvement medium; 4) preparation of improved dry and hot construction slag primary products by using the composite improvement medium, the air-dried construction slag and the garden waste compost product; and 5) standing and culturing of the improved dry and hot construction slag primary products to obtain improved planting soil. The application can solve the practical problems of difficult treatment of construction slag and garden waste, realize resource utilization of the construction slag in farmland, and meet the requirements of farmland resource protection, energy saving and emission reduction, environmental protection and economic benefits.

Description

Technical Field

[0001] This invention relates to a method for the resource utilization of construction waste in farmland. Background Technology

[0002] With rapid economic development and infrastructure construction, the proportion of construction waste has increased significantly, reaching approximately 30%-40% of total waste, and the amount of construction waste is growing at a rate of 10% annually. However, the resource utilization management of most construction waste is currently inadequate. Common disposal methods often involve directly dumping it outdoors or landfilling it, resulting in very low utilization rates. Improperly handled construction waste poses significant threats to the environment, economy, and safety. Construction waste contains a large number of bacteria, dust, and heavy metals, causing air pollution. Incineration of small amounts of construction waste can produce carcinogens, causing secondary air pollution. When the amount of construction waste piled up and landfilled exceeds a certain level, it may trigger geological disasters, such as mudslides or landslides. Furthermore, construction waste contains many recyclable resources, and direct landfilling or incineration can also damage the economy. Additionally, construction waste contains many sulfate ions, which can be converted into highly toxic hydrogen sulfide gas under anaerobic conditions, seriously affecting human health and safety. With economic and technological development, construction waste has become a major component of urban waste, and its disposal is a major headache for many cities. Improperly disposed construction waste not only damages the environment, economy, and resources but also affects human health. Currently, the main methods for disposing of construction waste are inefficient and polluting traditional methods such as landfill and incineration. Meanwhile, the shortage of arable land resources urgently needs to be addressed, but there is a lack of research on methods to improve high-quality soil suitable for crop cultivation using construction waste. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for the agricultural resource utilization of construction waste. The method of the present invention combines construction waste with garden waste, polymer compounds, soil amendment media, etc., to finally form usable planting soil for farmland.

[0004] To address the aforementioned technical problems, this invention provides a method for the agricultural resource utilization of construction waste, comprising the following steps:

[0005] 1) Drying and air-drying of construction waste: Construction waste must be air-dried;

[0006] 2) Garden waste composting: Obtain garden waste compost products;

[0007] 3) Preparation of composite modified media;

[0008] 4) Formation of improved dry-heated construction waste products (improved planting soil):

[0009] A primary product of modified dry heat-treated construction waste was prepared by using a composite amendment medium, air-dried construction waste, and garden waste compost.

[0010] The improved dry and heated construction waste is then left to stand and be cultivated to obtain improved planting soil.

[0011] An improvement to the method for utilizing construction waste in farmland as a resource of the present invention includes the following steps:

[0012] 1) Drying and air-drying of construction waste:

[0013] After removing large-diameter solids from construction waste (including muddy soil and solids such as stones and bricks), it is subjected to dry heat treatment. The resulting dry heat-treated construction waste is then air-dried, crushed, and sieved (2mm sieve) to obtain air-dried construction waste.

[0014] 2) Composting garden waste:

[0015] Five cubic meters of garden waste (including fallen leaves, bark, wood, and branches) were crushed (to a particle size of 5mm to 10mm), and then mixed with 0.45 to 0.55 cubic meters of urban sludge to obtain a mixture.

[0016] Mix 25±1 kg of urea and 2±0.1 kg of composting agent with water, spray the mixture onto the surface, mix thoroughly, and then pile the compost, controlling the compost moisture content to 55%–65%.

[0017] The temperature and humidity changes at the center of the compost pile are recorded every 24 hours. The temperature is required to not exceed 65℃ and the humidity to be controlled between 50% and 65% during the composting process. The composting process lasts for 5 months, and then the compost is crushed and sieved (through a 2mm sieve) to obtain garden waste compost products.

[0018] 3) Preparation of composite modified media

[0019] After air-drying the peat (Stanley peat soil) (to a moisture content of ≤5%), the air-dried peat, vermiculite, and perlite are mixed in a volume ratio of 3:1:2 to obtain a mixture of peat / vermiculite / perlite.

[0020] The mixture of peat / vermiculite / perlite is set at a weight ratio of 8-12% (preferably 10%) of air-dried construction waste; the solid polyacrylamide particles are set at a weight ratio of 0.08-0.12% (preferably 0.1%) of air-dried construction waste.

[0021] Weigh out polyacrylamide (anionic type, molecular weight: 15-18 million) and dissolve it in water to prepare an aqueous solution of polyacrylamide with a mass concentration of 0.8-1.2% (preferably 1%).

[0022] A polyacrylamide aqueous solution was sprayed into a mixture of peat / vermiculite / perlite and mixed evenly to obtain a composite modified medium;

[0023] 4) Formation of improved dry-heated construction waste soil (improved planting soil) products:

[0024] The weight ratio of garden waste compost products to air-dried construction waste is set at 8-12% (preferably 10%).

[0025] Add the composite modified medium obtained in step 3) to the air-dried construction waste obtained in step 1) and mix well. Then add the garden waste compost product obtained in step 2) and mix evenly to obtain the primary product of modified dry heat-treated construction waste.

[0026] The improved dry-heated construction waste primary product is added to a container, and water is added to 58-62% of the field water holding capacity of the improved dry-heated construction waste primary product. It is then statically cultured at room temperature for 9-11 days (preferably 10 days). During the static culture process, water is added appropriately to maintain the soil moisture content at 58-62% of the field water holding capacity. After the static culture is completed, the improved planting soil is obtained.

[0027] As a further improvement to the method for utilizing construction waste in farmland according to the present invention: in step 1):

[0028] Large-particle-size solids refer to solids with a particle size greater than 50 mm;

[0029] Dry heat treatment involves heating at 450±50℃ for 20±5 minutes (at which point the moisture content of the slag can be basically controlled to ≤20%).

[0030] Air dry until moisture content ≤5%;

[0031] Grind and pass through a 2mm sieve.

[0032] As a further improvement to the method for utilizing construction waste in farmland according to the present invention, in step 2):

[0033] Mix 25±1 kg of urea and 2±0.1 kg of composting agent with 30-35 L of water, spray the mixture onto the surface, mix thoroughly, and then pile it up.

[0034] Turn the compost pile every 10 days, adding an appropriate amount of water each time (usually about 25-35L) to maintain sufficient moisture content. If either the temperature or humidity does not meet the above conditions during the interval between two turnings, turn the pile earlier.

[0035] This invention is a novel method for the resource-based improvement of construction waste soil in farmland: it utilizes garden waste compost, polyacrylamide, and a mixture of peat:vermiculite:perlite (3:1:2) to jointly improve the structure and physicochemical properties of dry, heated construction waste soil. This invention employs methods from "Soil Agricultural Chemical Analysis (Third Edition)" and "Soil Physicochemical Analysis" to characterize the aggregate structure and other basic physicochemical properties of the improved soil.

[0036] The present invention relates to a method for improving construction waste soil through dry heating. This method utilizes garden waste and composting agents for composting, and then adds a 3:1:2 mixture of peat, vermiculite, and perlite, along with polyacrylamide, to the dry heating treated construction waste soil. This increases the soil's aggregate structure and improves its basic physicochemical properties, including bulk density, pH value, available nitrogen, and available phosphorus. This comprehensively enhances the quality and productivity of the construction waste soil, enabling its resource utilization in agricultural fields. The method is simple, uses readily available materials, and is inexpensive, thus possessing broad application prospects.

[0037] This invention has the following technical advantages:

[0038] This study proposes for the first time the combined use of garden waste compost, polyacrylamide, and a mixture of peat, vermiculite, and perlite as soil conditioner, added to dry-heated construction waste to improve soil structure and other basic properties. Based on the fundamental concept of soil improvement and resource utilization of garden waste, this approach fully integrates the practical problems of treating and reusing garden waste and construction waste. It identifies Ningbo construction waste, characterized by a lack of granular structure, high salinity, but rich organic matter content, as farmland soil with agricultural production potential, and uses garden waste as compost raw material and structural improvement material. This approach not only solves the practical difficulties in treating construction waste and garden waste but also enables the resource utilization of construction waste for farmland, thus meeting the needs of farmland protection, energy conservation and emission reduction, environmental protection, and economic benefits.

[0039] In summary, this invention utilizes construction waste soil for dry heat treatment and its applicability to agricultural production. It also uses garden waste compost combined with polyacrylamide and a mixture of peat, vermiculite, and perlite as improving materials to improve the soil structure of dry heat treated construction waste soil. At the same time, it also improves other physical and chemical properties of construction waste soil, thereby enhancing the agricultural productivity of construction waste soil and realizing the resource utilization of farmland. Attached Figure Description

[0040] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0041] Figure 1Comparison of the morphology of construction waste in Ningbo City before and after dry heat treatment; (A) Construction waste before dry heat treatment, (B) Construction waste after dry heat treatment;

[0042] Figure 2 The improved materials used in this invention are: (A) a garden waste compost product, and (B) a mixture of peat, vermiculite, perlite (volume ratio) and polyacrylamide in a ratio of 3:1:2.

[0043] Figure 3 To improve the morphology of planting soil.

[0044] Figure 4 A comparison of soil aggregate classification between PS0 (unimproved planting soil) and PS1 (improved planting soil).

[0045] Figure 5 The growth of rapeseed planted in PS0 (unimproved planting soil) and PS1 (improved planting soil) is compared. (A) shows the potted plants of the two treatments before harvest, and (B) shows the growth of individual rapeseed plants. T1 is the potted plant treatment using improved planting soil (PS1), and T0 is the treatment using unimproved planting soil (PS0). Detailed Implementation

[0046] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0047] Example 1: Improving construction waste soil using a mixture of garden waste compost, polyacrylamide, and peat vermiculite perlite, by following these steps:

[0048] 1) Drying and air-drying of construction waste (conventional technology):

[0049] Construction waste (including mud-like soil and solids such as stones and bricks) to be processed is separated by a separator and a screen to remove solids with a particle size greater than 50mm (these solids are disposed of as waste). The resulting material is named mud-like construction waste.

[0050] The separated mud-like construction waste was subjected to conventional dry heat treatment: the mud-like construction waste was placed in a dry heat treatment device and heated at 450℃ for 20 minutes to reduce the moisture content of the waste to a suitable dryness (i.e., controlling the moisture content of the waste to ≤20%). The result was named dry heat-treated construction waste. Figure 1 As shown.

[0051] according to Figure 1 It can be seen that dry heat treatment significantly improves the physical state of construction waste, effectively reduces soil moisture content, and makes construction waste more permeable and prevents it from hardening over a long period of time.

[0052] After the above-mentioned dry heat treatment, the construction waste soil is air-dried in a cool and ventilated place, and the soil moisture content is controlled to be ≤5%. After the air-dried soil is ground, it is all passed through a 2mm sieve to obtain the air-dried construction waste soil.

[0053] 2) Preparation of garden waste compost:

[0054] Garden waste can be collected from the Ningbo Jiangbei Green Waste Disposal Center. Take about 5 cubic meters of garden waste (including fallen leaves, bark, wood, branches, etc.), crush it to a particle size of 5mm to 10mm, and then add 0.5 cubic meters of urban sludge to obtain a mixture of garden waste and urban sludge (as a carrier for water and composting microorganisms).

[0055] Note: The heavy metal content of urban sewage sludge shall not exceed the standard (in accordance with the heavy metal content control standard for agricultural sewage sludge as specified in GB 4284-2018), and the proportion of biodegradable organic matter in the total mass of sludge shall be ≥40%.

[0056] Take a 50L plastic container, add 25kg of urea and 2kg of composting agent (straw composting agent, Yifuyuan JGFS-01), then add 30L of water, stir well to obtain a mixed solution.

[0057] Evenly sprinkle the mixed solution onto the mixture of garden waste and urban sludge, mix thoroughly, and then pile it up. At this point, the compost moisture content is approximately 55%. Place the probe of a temperature and humidity recorder at the center of the pile and record the temperature and humidity changes at the center of the pile every 24 hours. The temperature should not exceed 65℃ during composting, and the humidity should be controlled between 50% and 65%. Turn the pile every 10 days, adding approximately 30L of water each time (humidity should be controlled between 50% and 65%) to maintain sufficient moisture content and prevent the composting process from being hindered by water loss. If either the temperature or humidity does not meet the above conditions between two turnings, turn the pile earlier. Compost for 5 months, then appropriately pulverize it until it can pass through a 2mm sieve to obtain the garden waste compost product for later use. Figure 2 As shown in (A).

[0058] 3) Preparation of composite modified media (polyacrylamide + peat / vermiculite / perlite mixture):

[0059] After air-drying the peat (Stanley peat) to a moisture content of ≤5%, place three parts of air-dried peat, one part of vermiculite, and two parts of perlite in a spacious container in a volume ratio of 3:1:2. Use a plastic shovel to mix thoroughly to ensure that the components are mixed evenly and to avoid the formation of lumps, thus obtaining a mixture of peat / vermiculite / perlite.

[0060] Set the mixture of peat / vermiculite / perlite to 10% by weight of air-dried construction waste; set the solid polyacrylamide particles to 0.1% by weight of air-dried construction waste.

[0061] Weigh out solid polyacrylamide particles (anionic, molecular weight: 15-18 million) and slowly and evenly add them to a plastic container equipped with deionized water and a magnetic stirrer at a speed of 60 rpm to prevent clumping, thus preparing a 1% (mass%) polyacrylamide aqueous solution. Spray the polyacrylamide aqueous solution evenly and completely onto a mixture of peat / vermiculite / perlite using a spray bottle, continuously stirring the mixture to ensure uniform mixing of the polyacrylamide and the medium, resulting in a composite modified medium, such as... Figure 2 As shown in (B).

[0062] 4) Formation of improved planting soil:

[0063] The following composition is set for garden waste compost products: dried construction waste = 10% by weight;

[0064] Add the composite modified medium obtained in step 3) to the air-dried construction waste obtained in step 1) while stirring. After mixing, add the garden waste compost product obtained in step 2). Stir thoroughly again to ensure that all components are evenly mixed. The resulting product is named the modified dry heat-treated construction waste primary product.

[0065] The improved dry-heated construction waste soil was added to flowerpots, and water was added to 58-62% of the field capacity of the improved dry-heated construction waste soil. It was then left to stand at room temperature for 10 days, with appropriate water replenishment during this period to maintain a stable soil moisture content of 58-62% of field capacity, allowing the various components to fully integrate and stabilize. After the standing culture period, the final product was named the improved planting soil. Figure 3 As shown.

[0066] Experiment 1: Effects of the improved method on the granular structure and other physicochemical properties of dry-heated construction waste soil.

[0067] The improved planting soil obtained in Example 1 is labeled as PS1;

[0068] Comparative Example 1, relative to Example 1: steps 2) and 3) are omitted, and the improved dry-heated construction waste in step 4) is directly replaced with air-dried construction waste, and the rest is the same as Example 1; the resulting soil is named unimproved planting soil and labeled as PSO.

[0069] Both the unmodified treatment (PS0) and the modified treatment (PS1) were set to 3 replicates.

[0070] On the 10th day after static incubation, soil samples were collected for soil aggregate analysis, and basic chemical indicators such as soil pH, organic matter, total carbon, total nitrogen, available nitrogen, available phosphorus, and available potassium were measured. The methods for measuring each indicator were based on "Soil Agrochemical Analysis (Third Edition)" and "Soil Physicochemical Analysis," and the number of water-stable macroaggregates (R0) obtained by combining dry sieving and wet sieving methods was selected. 0.25 The following parameters were used as evaluation indicators for soil aggregate distribution and aggregate structure stability: large aggregate destruction rate (PAD), mean weight diameter (MWD), and geometric mean diameter (GMD). The calculation methods for each indicator are as follows:

[0071] 1) Number of water-stable macroaggregates (R) 0.25 ):

[0072]

[0073] In the formula, M i＞0.25 M represents the weight of aggregates with a particle size greater than 0.25 mm. T R represents the total weight of the aggregates. 0.25 When the content is less than 70%, it is called unstructured soil.

[0074] 2) Large Aggregate Disruption Rate (PAD):

[0075]

[0076] In the formula, DR >0.25mm The weight percentage (%) of agglomerates >0.25 mm obtained by dry sieving; WR >0.25mm The PAD value represents the weight percentage (%) of water-stable aggregates >0.25 mm obtained by wet sieving. The smaller the PAD value, the higher the soil aggregation degree and the stronger the aggregate stability.

[0077] 3) Weight-mean diameter (MWD) and geometric mean diameter (GMD):

[0078]

[0079] In the formula, w i x represents the weight percentage (%) of agglomerates of each particle size. i The average diameter (mm) of each particle size aggregate is denoted as MWD. ​​The higher the values ​​of MWD and GMD, the higher the soil aggregation degree and the stronger the aggregate stability.

[0080] The distribution of soil aggregates of different particle sizes after dry and wet sieving is as follows: Figure 4 As shown in Table 1 below, the measurement results of various evaluation indicators of the aggregates are presented.

[0081] Table 1. Comparison of soil aggregate structure stability indices

[0082] treatment <![CDATA[R 0.25 ]]> PAD MWD GMD PS1 78.67％±2.69％ 20.75％±2.89％ 2.236±0.241 0.999±0.105 PS0 50.66％±5.98％ 49.05％±6.01％ 0.580±0.029 0.300±0.028

[0083] Note: The results for each indicator in the table are all measured data after soil wet sieving. R 0.25 The table shows the number of water-stable macroaggregates, PAD represents the macroaggregate breakdown rate, MWD represents the average weight diameter, and GMD represents the geometric mean diameter. In the table, PS0 represents unimproved planting soil, and PS1 represents planting soil improved according to the method of this invention.

[0084] comprehensive Figure 4 According to the results in Table 1, compared with the unimproved planting soil (PSO), the improved method of the present invention, with the addition of 10% garden waste compost, 10% of a 3:1:2 peat / vermiculite / perlite mixture, and 0.1% polyacrylamide, increased the number of water-stable macroaggregates (R0) in the dry-heated construction waste soil. 0.25 The invention improved the soil aggregate structure by reducing the mean weight diameter (MWD) and geometric mean diameter (GMD) of construction waste, and decreased the soil aggregate destruction rate (PAD). The results indicate that the improvement effectively regulated the distribution of soil aggregates, increased the number and stability of large aggregates, and improved the soil aggregate structure. The addition of garden waste compost and polyacrylamide promoted the formation and stabilization of soil aggregates, reduced soil erosion and particle dispersion, and improved water conductivity. The porous structure and micro-uneven surface morphology of the peat / vermiculite / perlite mixture facilitated the bonding and aggregation of soil particles, directly increasing soil aeration while also promoting aggregate formation and stability. Aggregate structure has a significant impact on many physical and chemical properties of soil, plant growth, and fertility. Therefore, the effective improvement of soil aggregate structure in this invention is a key aspect of realizing the resource utilization of dry and hot construction waste in farmland.

[0085] Other soil physicochemical properties besides granular structure are shown in Table 2 below.

[0086] Table 2. Comparison of soil physical and chemical properties

[0087]

[0088] All physicochemical indicators in the table were measured with reference to "Soil Agrochemical Analysis (Third Edition)".

[0089] The results in Table 2 show that, compared with the unimproved planting soil (PS0), the improved planting soil (PS1) treated according to the method of this invention exhibits improvements in all basic physicochemical properties closely related to soil quality and fertility. Specifically, the treatment method effectively improved the alkalinity of the dried and heated construction waste soil, significantly reducing the pH value by approximately 0.4 units, making the soil more suitable for crop growth. The treatment method also significantly increased the organic matter, total carbon, and total nitrogen content of the dried and heated construction waste soil, possibly because the added garden waste compost and peat contain more organic matter and nitrogen. Furthermore, the treatment method increased the available nitrogen, phosphorus, and potassium content of the soil, especially significantly increasing the content of available nitrogen, thus addressing the problem of insufficient available nitrogen in the dried and heated construction waste soil. In summary, the improvement method adopted in this invention effectively improves the soil aggregate structure while also improving soil pH and nutrient status, thereby enhancing the soil quality and productivity of dried and heated construction waste soil from multiple aspects, providing a foundation and effective approach for its agricultural resource utilization.

[0090] Experiment 2: Comparison of the effects of dry-heated construction waste soil before and after improvement on the yield of rapeseed.

[0091] Pot experiments were conducted on improved planting soil (PS1) and unimproved planting soil (PS0) to demonstrate their practical application value in farmland (vegetable) production. Plastic pots with a diameter of 18 cm and a height of 19 cm were used in the pot experiments. The bottom layer of each pot contained a 5 cm thick layer of acidic farmland soil (pH approximately 4.33) as the substrate. Improved planting soil (PS1) was then spread evenly on the surface of the substrate to a thickness of 10 cm; this treatment was designated T1. Similarly, unimproved planting soil (PS0) was spread evenly on the surface of the substrate to a thickness of 10 cm; this treatment was designated T0. Each treatment had three replicates.

[0092] After filling the pots with soil, the plants were cultivated indoors at a ventilated and room temperature for 3 days to stabilize the soil moisture content (58-62% of the field capacity of the improved dry and hot construction waste). Then, rapeseed was planted. 30 rapeseed seeds (variety: Jingguan No. 1) were evenly sown in each pot by broadcasting, followed by a thin layer of air-dried soil (air-dried to a moisture content ≤5%) to cover the seeds. Deionized water was sprayed to moisten the surface soil (using deionized water provides a pure, ion-free water environment, ensuring the accuracy and reproducibility of the experimental results). The potted plants were cultivated indoors in a well-ventilated, sunny location, and their growth was continuously observed. Ten days after seed germination, seedlings were thinned to 7 plants per pot, maintaining plants with relatively uniform growth. During the rapeseed's growth period, deionized water was used for irrigation to maintain a water level of 60% field capacity until the rapeseed matured 50 days after sowing. The rapeseed plants were then harvested. No fertilizer was applied during the pot experiment. To control pests in the middle and late stages of rapeseed cultivation, the foliar insecticide Bacillus thuringiensis (suspension, 8000 IU / μL) was sprayed on the leaves on the 30th day after sowing.

[0093] For potted plants and rapeseed samples, photographs were taken promptly. The collected rapeseed plants were then washed with pure water, the surface moisture was patted dry, and their fresh weight was immediately measured. The plants were then placed in kraft paper and placed in an oven at 105℃ for 30 minutes to kill the greening, followed by drying at 70℃ until constant weight. The dry weight was measured and recorded. See below for potted rapeseed results and individual plant growth. Figure 5 The yield results of rapeseed cultivation using dry, hot construction waste soil before and after the improvement are shown in Table 3 below:

[0094] Table 3. Comparison of rapeseed yield in dry-heated construction waste soil before and after improvement.

[0095]

[0096] Note: T1 is the pot experiment treatment using improved planting soil (PS1), and T0 is the pot experiment treatment using unimproved planting soil (PS0).

[0097] From Table 3 and Figure 5The results show that, compared with the unimproved planting soil (PS0), the improved planting soil (PS1) obtained by the improvement method proposed according to this invention can significantly increase the yield of rapeseed. The fresh weight of rapeseed potted in the improved planting soil (PS1) increased by 159.4% and the dry weight increased by 140% compared with the unimproved planting soil (PS0) treatment. Furthermore, the improvement treatment of construction waste soil significantly increased both the weight of the above-ground and underground parts of the rapeseed, indicating that the improvement treatment can also promote root growth, which may be closely related to the effective improvement of soil physical structure. These results demonstrate that the pot experiment confirms the practical application value of the improved dry-heated construction waste soil of this invention in rapeseed production. The improvement treatment of construction waste soil can effectively increase the yield of rapeseed and significantly improve the agricultural productivity of construction waste soil.

[0098] This invention demonstrates that a method for improving dry-heated construction waste soil by adding amendments (i.e., 10% garden waste compost, 10% of a 3:1:2 peat / vermiculite / perlite mixture, and 0.1% polyacrylamide) can significantly alter the soil's aggregate structure, chemical conditions, nutrient status, and rapeseed yield. The improvement method of this invention can significantly improve the number of water-stable large aggregates (R0). 0.25 Soil aggregate structure evaluation indicators include large aggregate destruction rate (PAD), mean weight diameter (MWD), and geometric mean diameter (GMD), among which R... 0.25 The percentage of improved soil increased from 50.66% in unimproved soil to 78.67%, meeting the "structured" soil standard (R) of the aggregate structure theory. 0.25 (>70%). While effectively improving soil aggregate structure, the improvement method of this invention can also significantly reduce the alkalinity of dry and hot construction waste soil, increase the soil organic matter content and the available nitrogen, phosphorus and potassium nutrients. Among them, the content of available nitrogen in the soil increased by 559.9%, which can solve the problem of available nitrogen deficiency in the soil. Overall, the improvement method proposed in this invention effectively improves the physical and chemical properties of dry and hot construction waste soil, enhances the comprehensive quality of the soil and its agricultural production potential, and the significant increase in rapeseed yield in the pot experiment proves the productivity and practical application value of the improved dry and hot construction waste soil. Therefore, the improvement method of this invention is an effective way to realize the reuse of construction waste soil and garden waste and the resource utilization of farmland. The improvement method can improve the poor quality of dry and hot construction waste soil from the perspective of physical and chemical properties, making it more suitable for agricultural production, thereby effectively increasing the yield of rapeseed. The improved planting soil prepared according to this invention has the potential to be used as actual agricultural production soil, and has certain practical significance and application value in the green treatment of construction waste soil and the increase of arable land resources.

[0099] Comparative Example 2-1:

[0100] The use of "polyacrylamide solid particles" in step 3) of Example 1 is cancelled, that is, the amount of "polyacrylamide solid particles" is 0, and the rest is the same as in Example 1.

[0101] Comparative Example 2-2:

[0102] In step 3) of Example 1, the amount of "polyacrylamide solid particles" was changed from 0.1% to 0.2%, and the rest was the same as in Example 1.

[0103] Comparative Example 3:

[0104] Cancel the use of "garden waste composting products" in step 4) of Example 1, that is, the amount of "garden waste composting products" used is 0, and the rest is the same as in Example 1.

[0105] Comparative Example 4:

[0106] The use of "composite modified medium" in step 4) of Example 1 is cancelled, and the rest is the same as in Example 1.

[0107] All the comparative examples were tested according to the method described in Experiment 2. The results were as follows: the fresh weight of the plants in Comparative Example 2-1 was approximately 21.90±2.69 (g / plant), the fresh weight of the plants in Comparative Example 2-2 was approximately 22.16±0.33 (g / plant), the fresh weight of the plants in Comparative Example 3 was approximately 20.11±5.42 (g / plant), and the fresh weight of the plants in Comparative Example 4 was approximately 17.27±3.82 (g / plant), which were much smaller than the 29.16±7.06 (g / plant) obtained in Example 1.

[0108] Finally, it should be noted that the above examples are merely some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for the agricultural resource utilization of construction waste, characterized in that... Includes the following steps: 1) Drying and air drying of construction waste: After removing large-diameter solids from the construction waste, it is subjected to dry heat treatment. The resulting dry heat treatment construction waste is then air dried until the moisture content is ≤5%, crushed and sieved to obtain air-dried construction waste. Large-particle-size solids refer to solids with a particle size greater than 50 mm; Dry heat treatment involves heating at 450±50℃ for 20±5 minutes. 2) Composting of garden waste: Five cubic meters of garden waste were crushed and then mixed with 0.45 to 0.55 cubic meters of urban sludge to obtain a mixture. Mix 25±1 kg of urea and 2±0.1 kg of composting agent with water, spray the mixture onto the compost, mix thoroughly, and then pile it up, controlling the compost moisture content to 55%~65%. The temperature and humidity changes at the center of the compost pile are recorded every 24 hours. The temperature is required to not exceed 65℃ and the humidity to be controlled between 50% and 65% during the composting process. The composting process lasts for 5 months, and then the compost is crushed and sieved to obtain garden waste compost products. 3) Preparation of composite modified media: After air-drying the peat, the air-dried peat, vermiculite, and perlite are mixed in a volume ratio of 3:1:2 to obtain a mixture of peat / vermiculite / perlite. Set the weight ratio of the peat / vermiculite / perlite mixture to air-dried construction waste at 8-12%; set the weight ratio of polyacrylamide solid particles to air-dried construction waste at 0.08-0.12%. Weigh out polyacrylamide and dissolve it in water to prepare an aqueous solution of polyacrylamide with a mass concentration of 0.8-1.2%. A polyacrylamide aqueous solution was sprayed into a mixture of peat / vermiculite / perlite and mixed evenly to obtain a composite modified medium; 4) Formation of improved dry-heated construction waste products: The weight ratio of air-dried construction waste to garden waste compost products is set at 8-12%. Add the composite modified medium obtained in step 3) to the air-dried construction waste obtained in step 1) and mix well. Then add the garden waste compost product obtained in step 2) and mix evenly to obtain the primary product of modified dry heat-treated construction waste. The improved dry-heated construction waste primary product was added to a container, and water was added to 58-62% of the field water holding capacity of the improved dry-heated construction waste primary product. It was then statically cultured at room temperature for 9-11 days. During the static culture process, water was added as needed to maintain the soil moisture content at 58-62% of the field water holding capacity. After the static culture was completed, the improved planting soil was obtained.

2. The method for utilizing construction waste as farmland resource according to claim 1, characterized in that: In step 1): Grind and pass through a 2mm sieve.

3. The method for utilizing construction waste as farmland resource according to claim 2, characterized in that: In step 2): Mix 25±1 kg of urea and 2±0.1 kg of composting agent with 30~35 L of water, spray the mixture onto the surface, mix thoroughly, and then pile it up. Turn the compost pile every 10 days, adding water each time to maintain sufficient moisture content. If either the temperature or humidity does not meet the above conditions during the interval between two turnings, turn the pile earlier.

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