A household garbage solidification construction process based on a biological enzyme type soil solidifying agent

Abstract

The application discloses a household garbage solidification construction process based on a biological enzyme type soil solidifying agent and belongs to the technical field of soil solidification engineering. The process comprises the following steps: mixing and stirring biological enzyme liposomes, quicklime, cement, pre-mixed fluidized solidified soil and water to form a solidifying agent slurry; drilling a round hole downward in a household garbage site by using a drilling machine, then filling and grouting the solidifying agent slurry into the round hole, and then covering clay to complete the household garbage solidification construction process. The application takes tairan enzyme and pay enzyme as one of the raw materials of the biological enzyme solidifying agent, protects the biological enzyme, prepares biological enzyme liposomes with alkali resistance, then mixes the biological enzyme liposomes with quicklime, cement, pre-mixed fluidized solidified soil and water to form a solidifying agent slurry, fills the solidifying agent slurry into household garbage landfill soil by means of cement mixing pile machine drilling and grouting stirring, completes the treatment after solidification and sealing, and realizes the solidification and utilization of the garbage landfill site.

Description

Technical Field

[0001] This invention belongs to the field of soil solidification engineering technology, specifically relating to a construction process for solidifying municipal solid waste based on a bio-enzyme-based soil solidification agent. Background Technology

[0002] In a broad sense, any material used to reinforce soil should be called a soil stabilizer. In a narrow sense, soil stabilizers refer specifically to those used to solidify traditional materials such as cement and lime. Soil stabilizers are soil hardeners that can directly bind the surface of soil particles at room temperature or react with clay minerals to form cementitious substances. They can react with various types of soil to form stable and durable soil. As a new type of road construction material admixture, soil stabilizers have wide applicability. Practice has proven that soil reinforced with stabilizers has high strength, good water stability, and good resistance to drying shrinkage. After solidification, the soil forms a slab, becoming a semi-rigid road base or subbase. Its overall load-bearing performance is good, improving road quality, extending road service life, reducing project costs, and accelerating construction speed. It is a high-quality road construction material with comprehensive solidification and stability properties. Urban domestic waste refers to solid waste generated in daily urban life or in activities that provide services for daily urban life. Since the 1980s, with the growth of the urban population and the improvement of living standards, the amount of waste generated has also increased significantly. This waste not only pollutes the environment and damages the urban landscape, but also spreads diseases and threatens human life. How to deal with urban waste has become an important problem that countries around the world urgently need to solve.

[0003] The main methods of waste disposal include composting, incineration, and landfill. Composting involves the biochemical reaction of organic matter in waste under the action of microorganisms, ultimately forming a humus-like substance that can be used as fertilizer or soil conditioner. While foreign countries have adopted complete sets of machinery for composting operations, and my country has also conducted pilot projects, the complex composition and high inorganic content of Chinese waste have resulted in low composting efficiency, preventing the technology from being widely adopted domestically. Incineration involves the combustion reaction of combustible components in waste at high temperatures (800℃~1000℃), fully oxidizing the combustible components to produce harmless and stable ash, and recovering the heat energy for residential heating and power generation. Countries like Sweden and Japan have adopted waste incineration as a way to develop new energy sources. However, my country's municipal waste has a mixed composition and low calorific value (around 300-400 kcal). Furthermore, incineration requires significant investment, is complex to manage, has high processing costs, and generates significant pollution, hindering its widespread application in China. Currently, the most widely used waste disposal method is the construction of landfills. Early landfill construction was rather haphazard, resembling simple garbage dumps and causing significant pollution to the surrounding environment. Now, the construction of sanitary landfills for municipal solid waste has become a development trend in waste management. The primary goal in constructing sanitary landfills for municipal solid waste is to isolate the waste from the surrounding environment. The landfill method involves sending waste to a selected landfill site, spreading and compacting it in layers of a specific thickness within a defined area, and then covering it with soil and compacting it again after each day's work. The waste layer and the soil cover layer together constitute a filling unit, and a complete landfill is composed of several filling units. Once the landfill reaches its final designed height, a specially required clay layer is laid on top of the waste layer, followed by a layer of ordinary soil and compacted, ultimately forming a closed, sanitary landfill system. Landfilling is a method of waste disposal that can handle large volumes of waste, is technically simple, requires no pretreatment, is easy to manage, and has reasonable operating costs. It is the final disposal method for municipal waste and has been widely used in many countries around the world, making it the most common waste disposal method currently. In my country, landfilling is gradually becoming the main method of waste disposal, and many cities have already built landfills.

[0004] Landfills, as a method of solid waste disposal, can effectively treat waste in the short term, but their long-term existence may bring many harms and problems. The following are some of the main hazards of landfills: (1) Environmental pollution: Harmful substances in landfills, such as heavy metals, chemicals and organic pollutants, may seep into the soil, affecting the quality and function of the soil; leachate from landfill waste may pollute groundwater and surface water, causing water source pollution and affecting drinking water safety; during the landfilling process, some volatile organic compounds (VOCs) and odors may be released, leading to a decline in air quality and affecting the health of surrounding residents. (2) Health risks: Harmful gases (such as methane, ammonia, etc.) emitted by landfills may affect the respiratory system of surrounding residents, leading to respiratory diseases; spread of infectious diseases: Landfills may become breeding grounds for pathogens, increasing the risk of disease transmission, especially in summer and humid environments. (3) Ecological impacts: Loss of biodiversity: The construction of landfills usually requires the occupation of land, leading to the destruction of ecological habitats and affecting local plant and animal populations; Ecosystem damage: The existence of landfills may affect the balance of the surrounding ecosystems, causing the loss of ecological functions. (4) Waste of land resources: Landfills require a large amount of land resources, occupying available land for a long time and restricting its subsequent use, such as agriculture and urban development. (5) Economic costs: The pollution of landfills requires subsequent treatment and remediation, which may lead to high economic costs, including the cost of cleaning up, treating pollution and restoring the land. The harm of landfills is multifaceted, involving environmental, health, ecological and socio-economic fields. Therefore, in waste management, in addition to landfilling, we should also pay attention to the resource utilization of landfill sites after landfilling, so as to minimize the negative impact of landfills and increase the resource value of landfills.

[0005] Transforming landfill sites into engineered solidified soil is a novel and innovative way of utilizing resources, with many benefits: (1) Environmental protection: Converting landfill waste into engineered solidified soil can effectively reduce the amount of solid waste landfilled and alleviate the burden on landfills; through the solidification process, the risk of pollution to surrounding soil and water sources from landfills can be reduced, especially the leaching of heavy metals and harmful substances. (2) Resource reuse: Converting waste into engineering materials is in line with the concept of circular economy and helps to make efficient use of resources; using engineered solidified soil can reduce the demand for traditional building materials (such as sand and stone) and save natural resources. (3) Economic benefits: Using solidified soil as a building material can reduce the material cost of road construction; the production and treatment of solidified soil can drive the development of related industries and create new employment opportunities. (4) Improve soil properties: Solidified soil usually has high strength and stability, which can improve the bearing capacity and durability of roads; the solidification process can improve the drainage performance of solidified soil and reduce the risk of road water accumulation and soil erosion. (5) Technological innovation: The development of solidification technology can promote the research and application of new building materials and engineering technologies and promote the technological progress of the construction industry. (6) Social benefits: Transforming waste into usable engineering materials can enhance the city's environmental image and raise public awareness of sustainable development; by reducing the area and pollution of landfills, it can improve the living environment of surrounding communities and the health of residents.

[0006] Given the complexity of landfill sites, including the diverse composition of waste and the gradual degradation of organic matter over time, the settlement and deformation process is lengthy and unpredictable. Waste soil exhibits poor engineering mechanical properties, low shear strength, and high compressibility; after decomposition and cavitation, its self-bearing capacity is low, making it unsuitable for direct use in construction sites. Domestic and international research indicates that settlement of landfills after capping typically lasts for decades, with a total settlement of approximately 25%–50% of the initial landfill height; settlement due to organic matter degradation can reach 18%–24% of the total landfill height. Furthermore, the unique properties of municipal solid waste after landfilling (such as large voids, complex composition, and lack of soil structure) make it significantly different from traditional methods for reinforcing loose soil and silt. These factors make it difficult to solidify municipal solid waste landfill sites using conventional methods, thus rendering them unsuitable for construction.

[0007] Therefore, how to achieve the solidified utilization of urban waste landfill sites is a huge challenge. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention uses taurine and pyrazinamide as raw materials for a bio-enzyme curing agent. The bio-enzyme is protected and prepared into alkali-resistant bio-enzyme liposomes. These liposomes are then mixed with quicklime, cement, pre-mixed fluidized solidified soil, and water to form a curing agent slurry. This slurry is then injected into municipal solid waste landfill soil using a cement mixing pile machine for drilling and grouting. After curing, a sealing layer is formed, completing the treatment and solving the technical problems mentioned in the background art. Specifically, the technical solution of this invention includes the following:

[0009] A construction process for solidifying municipal solid waste based on a bio-enzyme-based soil stabilizer, comprising the following steps:

[0010] Biological enzyme liposomes, quicklime, cement, premixed fluidized solidified soil and water are mixed and stirred in a weight ratio of 0.01:1:2:1.5:5 to form a solidification slurry;

[0011] A circular hole 13.5 meters deep is drilled into the municipal solid waste site using a drilling machine. The solidifying agent slurry is then injected into the circular hole, and finally covered with clay to seal it, thus completing the municipal solid waste solidification construction process.

[0012] Furthermore, the method for preparing the bio-enzyme liposomes includes the following steps:

[0013] The enzyme, cholesterol, soybean lecithin and anhydrous ethanol are mixed to form an oil phase. The oil phase and the water phase are mixed and stirred at 400 r / min for 40 min. The mixture is then filtered to obtain the bio-enzyme liposome.

[0014] Furthermore, the mixed enzyme is composed of tazobacterium and pyrazinamide mixed in a mass ratio of 1:1.

[0015] Furthermore, the mass ratio of the mixed enzyme:penicillin:cholesterol:soy lecithin:anhydrous ethanol is 1:2:9:1000.

[0016] Furthermore, the aqueous phase is composed of deionized water.

[0017] Furthermore, the weight ratio of the oil phase to the water phase is 1:3.

[0018] Furthermore, the strength grade of the cement is P.O42.5R.

[0019] Furthermore, the preparation method of the premixed fluidized solidified soil includes the following steps:

[0020] The curing agent, additives, water, and soil are mixed in a mixer in a weight ratio of 10:1:20:69 to form the premixed fluidized solidified soil.

[0021] Furthermore, the curing agent is limestone.

[0022] Furthermore, the admixture is Polycarboxylate superplasticizer.

[0023] Furthermore, the soil material can be obtained from conventional trench excavation or other engineering waste soil material.

[0024] Furthermore, the amount of curing agent slurry used is 0.67 cubic meters of curing agent slurry per cubic meter of domestic waste.

[0025] Furthermore, the grouting process is performed twice.

[0026] Furthermore, the thickness of the covering clay for sealing is 2m.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The enzymes taurine and pyrazinamide used in this invention can promote the activity of soil microorganisms, releasing hydrogen ions and forming a pH gradient on the surface of soil particles. This helps to change the original soil structure and improve the soil's impermeability. A large number of organic molecules in the soil particles combine with biological enzymes to form intermediate reaction enzymes, which are then replaced and adsorbed by clay ions. This breaks down the double electric layer structure of the clay, reducing the hydrophilicity of the soil particles and forming a waterproof soil layer. After compaction, the soil loses its ability to absorb water again, and compaction does not affect the mechanical properties of the soil when exposed to water. Simultaneously, the biological enzyme liposomes adsorb sticky mineral particles in the soil, binding particles of different sizes together. This reduces the number of large pores and increases the number of small pores, increasing the cohesion and interaction between soil particles. Quicklime is used as a desiccant because of its strong dehumidifying function; it reacts with moisture in the air. At the same time, quicklime generates heat after entering the soil, achieving effective sterilization and disinfection. Premixed fluidized bed soil is made by fully utilizing soil from excavated trenches, foundation pits, or waste materials, then mixing it with a certain proportion of soil stabilizer, additives, and water, and mechanically mixing it thoroughly to form a pumpable, fluid reinforcement material. The fluidity of premixed fluidized bed soil can fill all voids in narrow spaces and irregularly shaped structures. Premixed fluidized bed soil has self-compacting properties, eliminating the need for large compaction and rolling equipment during construction, thus solving the problem of construction in some confined spaces. Furthermore, the construction method of mechanical premixing, centralized mixing, and on-site pouring of premixed fluidized bed soil results in uniform mixing, stable quality, and less susceptibility to site conditions and construction personnel factors during on-site pouring. However, due to the strong alkalinity of quicklime and the heat generated upon contact with water, taurine and pyrazinamide can easily lose their activity. Therefore, this invention mixes taurine, pyrazinamide, soybean lecithin, anhydrous ethanol, and cholesterol to form an oil phase, and then mixes and stirs the oil phase with the water phase to obtain bio-enzyme liposomes, thereby protecting taurine and pyrazinamide. A solidifying agent slurry is formed by mixing bio-enzyme liposomes, quicklime, cement, pre-mixed fluidized solidified soil, and water. The solidifying agent slurry is then filled into the municipal solid waste landfill soil by drilling and grouting with a cement mixing pile machine. After solidification, the treatment is completed, realizing the solidification and utilization of the landfill. Attached Figure Description

[0029] Figure 1 This is a diagram showing the result of solidification treatment of municipal solid waste site in Example 1.

[0030] Figure 2 This is a diagram showing the result of solidification treatment of municipal solid waste in Comparative Example 1.

[0031] Figure 3 This is a diagram showing the results of solidification treatment of municipal solid waste in Comparative Example 2. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise stated, all raw materials and reagents used in this invention are commercially available or can be prepared by known methods.

[0034] Preparation Example 1:

[0035] The preparation of biological enzyme liposomes specifically includes the following processes:

[0036] Weigh 3 mg of Terrazyme, 3 mg of Permazyme, 12 mg of cholesterol and 54 mg of soybean lecithin and put them into a flask. Then add 6 g of anhydrous ethanol and mix. Place the flask in a water bath at 45±1℃ until all the contents are dissolved and mixed evenly to obtain the oil phase and keep it warm.

[0037] Add 25g of deionized water to a new flask and heat to 55℃ to obtain the aqueous phase, then keep warm.

[0038] Subsequently, the oil phase was added dropwise to the aqueous phase at a weight ratio of 1:3 (oil phase to aqueous phase) at 55°C, and stirred at 400 rpm for 40 min. After stirring, the resulting mixture was placed on a rotary evaporator to remove anhydrous ethanol, and then filtered through a 0.22 μm filter membrane to obtain bio-enzyme liposomes, which were stored in a refrigerator at 4°C for later use.

[0039] Preparation Example 2:

[0040] The preparation of premixed fluidized solidified soil specifically includes the following processes:

[0041] Mix 10 parts by weight of limestone and 1 part by weight of additive. Polycarboxylate high-performance water-reducing agent, 20 parts by weight of water and 69 parts by weight of soil are mixed and placed in a mixer, and the mixer is turned on to form premixed fluidized solidified soil.

[0042] Example 1:

[0043] A construction process for solidifying municipal solid waste based on a bio-enzyme-based soil stabilizer specifically includes the following steps:

[0044] Take 1 part by weight of the bio-enzyme liposome obtained in Preparation Example 1, 100 parts by weight of quicklime, 200 parts by weight of cement, 150 parts by weight of the premixed fluidized solidified soil obtained in Preparation Example 2, and 500 parts by weight of water, mix and stir to form a solidifying agent slurry.

[0045] Multiple circular holes, each 13.5 meters deep, are drilled into the municipal solid waste site using a drilling machine. Then, according to the injection rate of 0.67 cubic meters of solidifying agent grout per cubic meter of municipal solid waste, the solidifying agent grout is injected into the circular holes to ensure full contact between the grout and the soil. Through physical compression, the solidifying agent grout forms a tight bond with the municipal solid waste. The grouting is performed twice, and then a 2-meter-thick layer of clay is used to seal the site, completing the municipal solid waste solidification process.

[0046] Comparative Example 1:

[0047] A solidification process for municipal solid waste includes the following steps:

[0048] The curing agent slurry in Example 1 was replaced with a mixture of cement, fly ash, soil, and water (cement, fly ash, soil, and water were mixed and added in a weight ratio of 2:1:5:1). Then, the grouting pipe with a nozzle was drilled to the predetermined position (13.5 meters deep) using a drilling rig. The curing agent slurry was injected at a rate of 0.55 cubic meters per cubic meter of domestic waste. The curing agent slurry was processed into a high-pressure stream and sprayed out of the nozzle using high-pressure equipment. The slurry impacted and broke up the soil, mixed with the soil, and formed a high-density concrete pile, thus completing the domestic waste curing construction process.

[0049] Comparative Example 2:

[0050] A solidification process for municipal solid waste includes the following steps:

[0051] The bio-enzyme liposomes in Example 1 were replaced with P-enzyme and T-enzyme (the two were mixed in equal amounts), and the grouting volume was set to 0.5 cubic meters of solidifying agent grout per cubic meter of domestic waste, with the remaining conditions consistent with Example 1.

[0052] On the 7th day after grouting, a site inspection and photographs were taken of the solidified domestic waste site. The results are shown in the figure. Figures 1-3 , Figure 1 This is a diagram showing the result of solidification treatment of municipal solid waste in Example 1. Figure 2 This is a diagram showing the result of solidification treatment of the municipal solid waste site in Comparative Example 1. Figure 3 This is a diagram showing the results of the solidification treatment of the municipal solid waste site in Comparative Example 2. On-site investigation revealed the following:

[0053] Example 1: After solidification treatment, the municipal solid waste site was free of odor and flies. Figure 1As can be seen, the waste is effectively fragmented, well-coated, and uniformly and fully solidified. The results of this experiment show that the combination of bio-enzyme liposomes, quicklime, cement, pre-mixed fluidized bed soil, and water is more effective in eliminating organic matter and achieving near-complete fragmentation of the waste.

[0054] Comparative Example 1: The solidified municipal solid waste site emitted a foul odor and had flies buzzing around it. Figure 2 It can be seen that the waste is basically not wrapped with solidifying material, the soil bearing capacity is low, the solidifying agent is unevenly distributed, and the solidification effect cannot be achieved. In the end, it is impossible to complete the leaching test of toxic substances, the physical permeability coefficient test and the foundation bearing capacity test.

[0055] Comparative Example 2: The solidified municipal solid waste site was virtually odorless and free of flies. Figure 3 It can be seen that the garbage wrapping effect is good, but the local filling is not full. However, it failed to achieve the best solidification effect and ultimately could not complete the leaching test of toxic substances, the physical permeability coefficient test, and the foundation bearing capacity test.

[0056] Seven days after grouting, the toxicity content of the solidified soil blocks after construction in Example 1 was tested, and the results are shown in Table 1.

[0057] Table 1 Results of Toxic Substance Content Detection

[0058]

[0059] On the 7th and 28th day after grouting, the physical permeability coefficient of the solidified soil block after construction in Example 1 was tested, and the results are shown in Table 2.

[0060] Table 2 Results of Physical Permeability Coefficient Test

[0061] Day 7 <![CDATA[2.75×10 -6 ]]> <![CDATA[≤1×10 -7 ]]> Not satisfied Day 28 <![CDATA[2.88×10 -7 ]]> <![CDATA[≤1×10 -7 ]]> satisfy

[0062] On the 14th and 28th day after grouting, three samples were taken from the solidified soil blocks after construction in Example 1 and numbered for testing. Then, plate load tests were conducted, and the results are shown in Table 3.

[0063] Table 3. Plate Load Test Results

[0064]

[0065] As can be seen from Table 3;

[0066] (1) The total load at the three test points (Y1 to Y3) after 14 days of curing was 360 kPa. The settlement was not significant, and there was no obvious lateral extrusion or heave of the soil around the pressure plate. The characteristic value of the bearing capacity of the foundation soil at the three test points within the influence depth of the pressure plate was fak = 180 kPa. The characteristic value of the bearing capacity of the foundation after 14 days of curing meets the design requirement of 180 kPa.

[0067] (2) The total load at the three test points (Y4 to Y6) after 28 days of curing was 640 kPa. The settlement was small, and there was no obvious lateral extrusion or heave of the soil around the pressure plate. The characteristic value of the bearing capacity of the foundation soil at the three test points within the influence depth of the pressure plate was fak = 320 kPa. The characteristic value of the foundation bearing capacity after 28 days of curing meets the design requirement of 320 kPa.

[0068] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A construction process for solidifying municipal solid waste based on a bio-enzyme-based soil stabilizer, characterized in that, The solidification process for municipal solid waste includes the following steps: Biological enzyme liposomes, quicklime, cement, premixed fluidized solidified soil and water are mixed and stirred in a weight ratio of 0.01:1:2:1.5:5 to form a solidification slurry; A circular hole 13.5 meters deep is drilled into the municipal solid waste site using a drilling machine. The solidifying agent slurry is then injected into the circular hole, and finally covered with clay to seal it, thus completing the municipal solid waste solidification construction process.

2. The construction process for solidifying municipal solid waste based on a bio-enzyme-based soil stabilizer according to claim 1, characterized in that, The method for preparing the bio-enzyme liposomes includes the following steps: A mixture of enzyme, cholesterol, soybean lecithin, and anhydrous ethanol is formed to create an oil phase. The oil phase is then mixed with an aqueous phase and stirred at 400 rpm for 40 minutes. The mixture is then filtered to obtain the bio-enzyme liposomes. The mixed enzyme is composed of tazobacterium and pyrazinamide mixed in a mass ratio of 1:

1.

3. The construction process for solidifying municipal solid waste based on a bio-enzyme-based soil stabilizer according to claim 2, characterized in that, The mass ratio of the mixed enzyme, cholesterol, soybean lecithin, and anhydrous ethanol is 1:2:9:1000.

4. The construction process for solidifying municipal solid waste based on a bio-enzyme-based soil stabilizer according to claim 2, characterized in that, The weight ratio of the oil phase to the water phase is 1:

3.

5. The construction process for solidifying municipal solid waste based on a bio-enzyme-based soil stabilizer according to claim 1, characterized in that, The preparation method of the premixed fluidized solidified soil includes the following steps: The curing agent, additives, water, and soil are mixed in a mixer in a weight ratio of 10:1:20:69 to form the premixed fluidized solidified soil.

6. The construction process for solidifying municipal solid waste based on a bio-enzyme-based soil stabilizer according to claim 5, characterized in that, The curing agent is limestone.

7. The construction process for solidifying municipal solid waste based on a bio-enzyme-based soil stabilizer according to claim 5, characterized in that, The additive is PCA®-Ⅰ polycarboxylate high-performance water-reducing agent.

8. The construction process for solidifying municipal solid waste based on a bio-enzyme-based soil stabilizer according to claim 1, characterized in that, The amount of curing agent slurry used is 0.67 cubic meters per cubic meter of municipal solid waste site.

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