Waste disposal methods

Abstract

The present invention provides a waste disposal method that can prevent or suppress the spread of contamination from waste buried in the soil to the surrounding area. [Solution] A waste treatment method comprising the steps of: an excavation step of digging a hole in the ground of land to bury the waste; a deposit step of depositing the waste into the hole; a burying step of backfilling the hole with soil and sand; a spraying step of spraying a treatment agent containing a thermoplastic resin onto the surface of the backfilled soil and sand; and a forming step of forming a waterproof layer of thermoplastic resin on the surface of the soil and sand, wherein in the burying step, soil and sand are used to form an embankment.

Description

[Technical Field]

[0001] This invention relates to a method for disposing of waste buried in the ground. [Background technology]

[0002] As people conduct their daily lives in society, vast amounts of various types of waste are continuously generated. Disposing of such waste is a universal challenge in industry and an urgent issue that society as a whole must address. Methods of waste disposal include, for example, landfill, incineration, ocean dumping, and biological treatment. Of these, landfill is relatively simple and low-cost, and does not produce carbon dioxide like incineration, so it remains widely used in many industries.

[0003] When burying waste is chosen as a waste disposal method, measures are required to prevent harmful or toxic substances contained in the buried waste from leaking into the surrounding area due to rainwater or moisture contained in the waste itself. In this regard, there has been a conventional technology to form a synthetic resin film on the surface of the soil layer covering the waste that allows gas to permeate but blocks rainwater (see Patent Document 1).

[0004] According to Patent Document 1, it is possible to prevent most rainwater from seeping into the waste, and since the decomposition gases generated from the waste can be released through the ground, the generation of leachate from rainwater can be reduced as much as possible. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-226535 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in the method described in Patent Document 1, if the buried waste decreases in volume due to decay, deterioration, oxidation, decomposition, etc., the covering soil layer may sink due to its weight, causing a sinkhole to form in the ground. When the covering soil layer sinks, the synthetic resin film formed on the surface of the covering soil layer is destroyed, and if rainwater or other liquids accumulate in the sinkhole in this state, there is a risk that harmful or toxic substances contained in the waste will dissolve in the water and flow into the surrounding area.

[0007] This invention has been made in view of the above-mentioned problems, and aims to provide a waste treatment method that can prevent or suppress the spread of contamination from waste buried in the soil to the surrounding area. [Means for solving the problem]

[0008] The characteristic configuration of the waste treatment method according to the present invention, which solves the above problems, is as follows: The excavation process involves digging a hole in the ground where the waste will be buried, A feeding step of putting waste into the aforementioned hole, The burying process involves backfilling the aforementioned hole with soil and sand, A spraying step in which a treatment agent containing a thermoplastic resin is sprayed onto the surface of the backfilled soil, A forming step of forming a waterproof layer of the thermoplastic resin on the surface of the soil and sand. It includes, The aforementioned burial process involves forming an embankment with the aforementioned soil and sand.

[0009] According to this waste disposal method, a hole is dug in the ground where the waste will be buried (excavation step), the waste is placed in the hole (placement step), the hole is then backfilled with soil (burial step), a treatment agent containing thermoplastic resin is sprayed on the surface of the backfilled soil (spraying step), and then a waterproof layer of thermoplastic resin is formed on the surface of the soil (forming step). This simple method prevents or suppresses water infiltration into the soil, thus reducing the risk of harmful or toxic substances contained in the waste flowing into the surrounding area due to rainfall or flooding, and maintaining a safe environment. Furthermore, by forming an embankment with soil during the burial step, the thickness of the soil covering the waste is increased, stabilizing the buried waste under its own weight, allowing for stable storage in the soil over a long period. Moreover, even if the volume of the buried waste decreases due to decay, deterioration, oxidation, decomposition, etc., the embankment gradually sinks into the resulting voids in the soil, preventing ground subsidence (collapse). Furthermore, because the embankment sinks gradually, sudden changes in shape do not occur, which maintains the waterproof layer of thermoplastic resin formed on the surface of the soil. As a result, ground subsidence (collapse) is prevented, and rainwater does not accumulate on the ground. Therefore, the spread of contamination from buried waste to the surrounding area can be prevented or suppressed.

[0010] In the waste treatment method according to the present invention, In the aforementioned burial process, it is preferable not to compact the soil.

[0011] According to this waste disposal method, by not compacting the soil during the burial process, the waste in the soil is not crushed by pressure, and the leakage of harmful and toxic substances from the waste can be reduced. Furthermore, since the shape of the soil can be sufficiently maintained by the thermoplastic resin layer (waterproof layer) even without compaction, it can be said that this method is efficient in terms of eliminating the need for compaction work.

[0012] In the waste treatment method according to the present invention, In the aforementioned burial process, it is preferable to use the soil generated in the excavation process as the soil used to backfill the hole.

[0013] According to the method for treating waste of this configuration, in the embedding process, by using the earth and sand generated in the excavation process as the earth and sand for backfilling the hole, the generated earth and sand can be effectively reused. Further, since the same earth and sand are handled in the excavation process and the embedding process, the properties of the land for treating waste do not change, and the treatment can be carried out safely and appropriately.

[0014] In the method for treating waste according to the present invention, In the spraying process, the content of the thermoplastic resin contained in the treatment agent is preferably 3 to 10.5% by weight.

[0015] According to the method for treating waste of this configuration, in the spraying process, by setting the content of the thermoplastic resin contained in the treatment agent to 3 to 10.5% by weight, a good thermoplastic resin layer (waterproof layer) is formed on the surface of the earth and sand, so that harmful substances and toxic substances contained in the waste can be surely prevented from flowing out to the surroundings due to rainfall, flooding, etc.

[0016] In the method for treating waste according to the present invention, In the spraying process, the spraying amount of the treatment agent is preferably 0.5 kg / m 2 or more.

[0017] According to the method for treating waste of this configuration, in the spraying process, by setting the spraying amount of the treatment agent to 0.5 kg / m 2 or more, the treatment agent can reach an appropriate depth from the soil surface, and a good thermoplastic resin layer (waterproof layer) can be formed as a waterproof layer on the soil surface. As a result, harmful substances and toxic substances contained in the waste can be surely prevented from flowing out to the surroundings due to rainfall, flooding, etc.

[0018] In the method for treating waste according to the present invention, In the charging process, it is preferable to charge a superabsorbent polymer into the hole together with the waste.

[0019] According to this waste treatment method, by introducing a superabsorbent polymer into the hole along with the waste during the input process, even if the soil to be buried or the waste itself contains a large amount of moisture, the superabsorbent polymer can absorb the moisture. This reliably prevents harmful or toxic substances contained in the waste from leaking into the surrounding area due to moisture in the soil or moisture seeping from the waste. Furthermore, as the superabsorbent polymer absorbs moisture and swells, the waste buried in the soil is densely surrounded and protected by the swollen superabsorbent polymer, thus contributing to the long-term and stable storage of the waste.

[0020] In the waste treatment method according to the present invention, In the spraying step, it is preferable that the thermoplastic resin contained in the treatment agent is an ethylene vinyl acetate copolymer (EVA).

[0021] According to this waste treatment method, by using ethylene vinyl acetate copolymer (EVA) as the thermoplastic resin contained in the treatment agent, a durable thermoplastic resin layer (waterproof layer) can be formed on the surface of the soil. Furthermore, since the treatment agent containing ethylene vinyl acetate copolymer (EVA) can be sprayed onto the surface of the soil in the form of a solution (emulsion), it can be said to have excellent workability in the spraying process.

[0022] In the waste treatment method according to the present invention, The aforementioned waste is preferably animal waste.

[0023] This waste disposal method is particularly effective for disposing of animal waste that poses a risk of spreading infection, especially when ordered to be disposed of by local governments. Animal waste buried in the soil is prone to decomposition and its volume is reduced, but even if voids are created in the soil due to this volume reduction, the embankment will gradually sink, preventing ground subsidence (collapse). In addition, because a waterproof layer of thermoplastic resin is present on the surface of the soil, rainwater and other liquids are less likely to penetrate to the animal waste in the soil, thus preventing or suppressing the spread of contamination to the surrounding area. [Brief explanation of the drawing]

[0024] [Figure 1] Figure 1 is a schematic diagram illustrating the waste treatment method of the present invention. [Modes for carrying out the invention]

[0025] The applicant previously invented a method for disposing of chickens culled in the event of a highly pathogenic avian influenza outbreak and filed a patent application for this invention (although the patent application for the said invention was not published at the time of filing the present application, it has been granted a patent). This invention is a groundbreaking technology that can solve the problem of disposing of discarded chickens that becomes apparent when avian influenza outbreaks occur. Subsequently, the applicant has conducted further studies on this technology and made improvements and refinements to make it applicable to many types of waste other than chickens (discarded chickens).

[0026] Specifically, focusing on the fact that many hazardous and toxic substances contained in waste are easily soluble in water or easily transfer to water, we conducted a study based on the understanding that preventing water infiltration into the ground where waste is buried is important in order to prevent the spread of contamination by waste. We then considered that if we built an embankment on top of the buried waste and solidified the surface of the embankment (soil) with a highly water-resistant thermoplastic resin, water infiltration into the ground would be prevented or suppressed, and the risk of hazardous and toxic substances contained in the buried waste dissolving in water or transferring to water and flowing into the surrounding area would be reduced. As will be explained in detail in the examples described later, we sprayed a treatment agent containing ethylene vinyl acetate copolymer (EVA), an example of a thermoplastic resin, onto simulated soil to solidify the surface soil, and conducted an immersion test on this simulated soil, confirming a high water infiltration suppression effect.

[0027] Thus, the present invention was completed based on the discovery that waste can be safely and appropriately treated even after being buried in the ground by treating soil (especially embankments) with a thermoplastic resin. The waste treatment method of the present invention involves spraying a treatment agent containing a thermoplastic resin onto the surface of the soil in which the waste is buried, and is a technology applicable to the treatment of all types of waste buried in the ground. Examples of waste include animal waste such as livestock and fish, plant waste such as vegetable scraps and wood chips, and mineral waste such as concrete rubble and iron scraps.

[0028] The waste treatment method of the present invention is highly safe and therefore particularly effective for treating animal waste where the spread of infection is a concern. Examples of animal waste include pigs culled due to outbreaks of classical swine fever (formerly classical swine cholera), cattle culled due to outbreaks of foot-and-mouth disease, and other animals culled due to outbreaks of statutory infectious diseases of livestock designated under Japan's Act on the Prevention of Infectious Diseases of Domestic Animals. Chickens culled due to outbreaks of avian influenza may also be included, but this is not essential in the present invention.

[0029] The following describes embodiments of the waste treatment method of the present invention. However, the present invention is not limited to these embodiments.

[0030] <Treatment chemicals> In the waste treatment method of the present invention, a thermoplastic resin or a composition containing a thermoplastic resin is used as a treatment agent to solidify the soil. Examples of thermoplastic resins include ethylene vinyl acetate copolymer (EVA), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS). Of these thermoplastic resins, ethylene vinyl acetate copolymer (EVA) is preferred. In ethylene vinyl acetate copolymer (EVA), the ratio of ethylene component to vinyl acetate component is not particularly limited, but a higher proportion of ethylene component can form a flexible film, and a higher proportion of vinyl acetate component can form a hard film. Therefore, when selecting ethylene vinyl acetate copolymer (EVA) to be used as a treatment agent, the ratio of ethylene component to vinyl acetate component should be appropriate depending on the properties of the soil to be treated. For example, by setting the proportion of ethylene component in ethylene vinyl acetate copolymer (EVA) to about 3-10% (molar equivalent), a film with a balanced combination of flexibility and hardness can be formed, making it possible to treat a wide range of soils.

[0031] Furthermore, the treatment agent can also contain disinfectants, antibacterial agents, antiviral agents, deodorizers, thickeners, dispersants, etc., in addition to thermoplastic resins.

[0032] The dosage form of the treatment agent is preferably an emulsion in which a thermoplastic resin is dispersed in a solvent, and in particular, an aqueous emulsion in which a thermoplastic resin is dispersed in water. Furthermore, the content of the thermoplastic resin (solids) in this emulsion (treatment agent) is preferably 3 to 10.5% by weight. Within this range, the soil will harden appropriately, so a good thermoplastic resin layer can be formed on the soil surface as a waterproof layer. If the thermoplastic resin content in the treatment agent is less than 3% by weight, the soil may not be able to harden sufficiently. On the other hand, if the thermoplastic resin content in the treatment agent exceeds 10.5% by weight, cracks may occur on the surface of the hardened soil (thermoplastic resin layer).

[0033] When using (spraying) an emulsion-type treatment agent, the amount to be used (sprayed) is 0.5 kg / m² relative to the soil surface (embankment surface). 2 Preferably, it is 1 kg / m 2 It is more preferable that the amount of treatment agent used is 0.5 kg / m². 2 If the above conditions are met, the treatment agent will penetrate to an appropriate depth (for example, 1 to 10 cm) from the soil surface, forming a good thermoplastic resin layer (waterproof layer) on the soil surface. The amount of treatment agent used is 0.5 kg / m². 2 If the amount is less than 5 kg / m³, the treatment agent may not penetrate the soil sufficiently, remaining near the soil surface and potentially failing to properly compact the soil. On the other hand, there is no particular upper limit on the amount of treatment agent to be used, but considering the cost of using the treatment agent, 5 kg / m³ is recommended. 2 The degree is realistic.

[0034] <Waste disposal methods> The waste treatment method of the present invention, which uses the treatment agents described above, will now be explained. Figure 1 is a schematic diagram illustrating the waste treatment method of the present invention. The waste treatment method of the present invention comprises five steps: an excavation step, a loading step, a burial step, a spreading step, and a formation step. Each step will be described in detail below.

[0035] <Excavation Process> In the excavation process, a hole 2 is dug in the ground 1 of the land where the waste to be processed will be buried [Figures 1(a) and (b)]. The land where the waste will be buried is not particularly limited, but if the waste is animal waste such as livestock, it is usually set up on the premises of a facility where livestock are raised. Since the waste is disposed of in flexible container bags, for example, the size of the hole 2 should be large enough to fit several to a dozen or so flexible container bags (diameter 1100 mm, height 1100 mm, capacity 1000 L). Regarding the excavation means 3 for excavating the hole 2, a shovel (spade) is illustrated in Figure 1(b) for ease of explanation, but it is common to use heavy machinery such as a backhoe. The soil 4 generated by excavating the hole 2 is temporarily placed near the hole 2.

[0036] <Input process> In the input process, waste (for example, a flexible container bag containing the waste) 5 is placed into the hole 2 [Figure 1(c)]. Preferably, the waste 5 placed in the hole 2 is filled to a depth of about 2 / 3 of the depth of the hole 2. It is also desirable that the waste 5 be placed so that it is aligned at the bottom of the hole 2. In the input process, it is also possible to place a superabsorbent polymer (not shown) into the hole 2 together with the waste 5. In this case, the superabsorbent polymer may be placed inside the flexible container bag containing the waste 5 together with the waste 5, or the superabsorbent polymer may be placed around the flexible container bag containing the waste 5 to prepare for damage to the flexible container bag. By placing a superabsorbent polymer into the hole 2 together with the waste 5, even if the soil to be buried or the waste 5 itself contains moisture, the superabsorbent polymer can absorb the moisture, thus reliably preventing harmful or toxic substances contained in the waste 5 from flowing into the surrounding area due to moisture in the soil or moisture seeping from the waste 5. Furthermore, as the superabsorbent polymer absorbs moisture and swells, the waste 5 buried in the soil is densely surrounded and protected by the swollen superabsorbent polymer, thus contributing to the long-term and stable storage of the waste 5.

[0037] <Burial process> In the burial process, the hole 2 is backfilled with soil 4 [Figure 1(d)]. Here, in this invention, it is essential to form an embankment with soil 4. Because the embankment increases the thickness of the soil 4 covering the waste 5, the buried waste 5 is stabilized by the weight of the soil 4 and stored stably in the soil. When the waste 5 buried in the soil decreases in volume due to decay, deterioration, oxidation, decomposition, etc., voids may form in the soil. However, as shown in Figure 1(d), if an embankment is formed with soil 4, as shown in Figure 1(f), the embankment will sink into the voids in the soil caused by the volume reduction, thus preventing ground subsidence (collapse). Furthermore, it is preferable not to compact the backfilled soil (embankment) 4. Compaction refers to hardening the ground with tools or heavy machinery such as rollers or rammers. In road construction and the like, the laid soil is usually compacted to increase the strength of the soil surface, but compaction transmits pressure into the soil. In particular, if the waste 5 is relatively soft, such as animal waste, it is preferable not to compact the backfill soil (embankment) 4 in order to avoid crushing the buried waste 5 under pressure. The soil 4 used to backfill the hole 2 is the soil 4 generated in the excavation process. This allows for the effective reuse of the soil 4. Furthermore, since the same soil 4 is handled in both the excavation and burial processes, the properties of the land where the waste 5 is processed do not change, and the waste can be processed safely and appropriately.

[0038] <Spraying process> In the spraying process, a treatment agent 6 containing a thermoplastic resin is sprayed onto the surface of the backfilled soil (embankment) 4 [Figure 1(e)]. Ethylene vinyl acetate copolymer (EVA) is preferred as the thermoplastic resin. Ethylene vinyl acetate copolymer (EVA) can form a durable thermoplastic resin layer (waterproof layer) 7 on the surface of the soil (embankment) 4. Furthermore, since the treatment agent containing ethylene vinyl acetate copolymer (EVA) can be sprayed onto the surface of the soil (embankment) 4 in the form of a solution (emulsion), it offers excellent workability in the spraying process. The means of spraying the treatment agent 6 are not particularly limited; for example, a spraying device 11 consisting of a chemical tank 8, a pump 9, and a shower head 10, as shown in the figure, can be used. The thermoplastic resin content in the treatment agent 6 is preferably 3 to 10.5% by weight. The amount of treatment agent 6 sprayed is 0.5 kg / m². 2 The above is preferable. These are as explained in the "Treatment Agents" section above.

[0039] <Formation process> When the treatment agent 6 sprayed on the surface of the soil (embankment) 4 dries, a thermoplastic resin layer (waterproof layer) 7 is formed on the surface of the soil 4. The presence of the thermoplastic resin layer (waterproof layer) 7 on the surface of the soil 4 makes it difficult for rainwater, etc., to penetrate to the waste 5 in the soil, thereby preventing or suppressing the spread of contamination to the surrounding area. In particular, when the waste 5 is animal waste, animal waste becomes more soluble in water due to decomposition and decay, and furthermore, as shown in Figure 1(f), the volume may decrease and the soil 4 may settle. However, by providing a thermoplastic resin layer (waterproof layer) 7 on the surface of the soil 4 to prevent the intrusion of rainwater, etc., it is extremely useful in that it can prevent or suppress the spread of contamination to the surrounding area.

[0040] As described above, the waste disposal method of the present invention involves a simple method in which water infiltration into the soil is prevented or suppressed. This reduces the risk of harmful or toxic substances contained in the waste 5 flowing into the surrounding area due to rainfall or flooding, thus maintaining a safe environment. Furthermore, by forming an embankment with soil 4 during the burial process, the thickness of the soil 4 covering the waste is increased, allowing the buried waste 5 to be stabilized by the weight of the soil 4 and stored stably in the soil. Furthermore, even if the waste 5 buried in the soil decreases in volume due to decay, deterioration, oxidation, decomposition, etc., the embankment will sink into the resulting voids in the soil, preventing ground subsidence (collapse). Also, even if the embankment collapses, it will do so gradually, preventing abrupt changes in the shape of the ground, and the thermoplastic resin waterproof layer 7 formed on the surface of the soil will be maintained. As a result, in addition to preventing ground subsidence (collapse), it is possible to prevent rainwater from accumulating on the ground. Therefore, it is possible to prevent or suppress the spread of contamination from the waste 5 buried in the soil to the surrounding area. Moreover, by not compacting the soil 4, the waste 5 in the soil will not be crushed by pressure, and the leakage of harmful and toxic substances from the waste 5 can be reduced. In addition, since the shape of the soil 4 can be sufficiently maintained by the thermoplastic resin layer (waterproof layer) 7 even without compaction of the soil 4, it can be said that this method is efficient in that compaction work can be omitted.

[0041] Further, according to the method for treating waste of the present invention, even when the flexible container (treatment container) buried in the soil is damaged and harmful substances or toxic substances derived from the waste 5 leak out from the flexible container, the thermoplastic resin layer (waterproof layer) 7 formed on the surface of the earth and sand (embankment) 4 can prevent or suppress the intrusion of water into the soil. Therefore, the risk of harmful substances or toxic substances contained in the waste 5 flowing out due to rainfall, inundation, etc. is reduced, and the waste 5 can be maintained and stored in a safe state in the soil.

Example

[0042] In order to verify the effect of the method for treating waste of the present invention, a water immersion test of earth and sand treated with a treatment agent was carried out.

[0043] <Chemicals and Materials Used> The chemicals and materials used in the test are as follows. ·Treatment agent: Ethylene vinyl acetate copolymer (EVA) aqueous emulsion (solid content of stock solution: 21% by weight) ·Comparative agent: Carboxymethyl cellulose (CMC) ·Clay: Clay produced in Tochigi Prefecture (Tochikure (registered trademark)) ·Sand: Mixed sand prepared by mixing No. 3 silica sand and No. 5 silica sand at a weight ratio of 1:1

[0044] <Reproduction of Rainfall> According to the website of the Ministry of Land, Infrastructure, Transport and Tourism, the average annual precipitation in Japan is 1718 mm. Also, according to the website of the Japan Meteorological Agency, a situation where the hourly rainfall is 50 mm or more and less than 80 mm is regarded as "very heavy rain", and a situation where the hourly rainfall is 80 mm or more is regarded as "extremely heavy rain". Based on this information, in this water immersion test, the target range was defined as 120 mm × 120 mm (0.0144 m 2 ), and the precipitation (volume) and the intensity of rain (flow rate) were simultaneously reproduced by generating the precipitation for half a year in a short period of time.

[0045] [Precipitation (Volume)] Although the calculation formula is omitted, from the average annual precipitation of 1718 mm in Japan to 0.0144 m 2The amount of rainfall (volume) that fell in this area over a six-month period can be calculated to be approximately 13 liters.

[0046] [Rain intensity (flow rate)] By continuously spraying tap water at a flow rate of 1.3 liters per minute for 10 minutes using a garden shower, we were able to reproduce the aforementioned six-month rainfall (volume) of 13 liters. Although the calculation formula is omitted, converting this rainfall (volume) to an hourly rate results in 78 mm, which corresponds to "very heavy rain" as defined by the Japan Meteorological Agency.

[0047] <Preparation of simulated soil> To simulate the soil generated when excavating land for waste burial, clay and sand were mixed by weight in the following proportions: (1) 100%:0%, (2) 70%:30%, and (3) 50%:50%. Each mixed soil was then watered and stirred until it reached a state equivalent to typical excavated soil to obtain reproduced soils A to C. It should be noted that watering and stirring the mixed soil causes some of the soil to aggregate, resulting in greater variation in particle size. Furthermore, the aggregated soil has larger gaps, which may make it difficult to accurately evaluate the soil immersion test. Therefore, a sieve with a mesh size of 2.0 mm was used for sieving, and the material that passed through the sieve was used as the reproduced soil for the test. The formulations of reproduced soils A to C are shown in Table 1.

[0048] [Table 1]

[0049] <Water immersion test> Soil immersion tests were conducted using the treatment agents described in Examples 1 to 8 below. For comparison, soil immersion tests were also conducted using the treatment agent in Comparative Example 1, or under the conditions of Comparative Examples 2 and 3.

[0050] [Example 1] A stock solution of ethylene vinyl acetate copolymer (EVA) aqueous emulsion with a solid content of 21% by weight was diluted twice with water to serve as the treatment agent for Example 1 (solid content 10.5% by weight).

[0051] [Example 2] A stock solution of ethylene vinyl acetate copolymer (EVA) aqueous emulsion with a solid content of 21% by weight was diluted five times with water to be used as the treatment agent for Example 2 (solid content 4.2% by weight).

[0052] [Example 3] A stock solution of ethylene vinyl acetate copolymer (EVA) aqueous emulsion with a solid content of 21% by weight was diluted 6 times with water to form the treatment agent for Example 3 (solid content of 3.5% by weight).

[0053] [Example 4] A stock solution of ethylene vinyl acetate copolymer (EVA) aqueous emulsion with a solid content of 21% by weight was diluted 7 times with water to serve as the treatment agent for Example 4 (solid content 3.0% by weight).

[0054] [Example 5] A stock solution of ethylene vinyl acetate copolymer (EVA) aqueous emulsion with a solid content of 21% by weight was diluted eightfold with water to serve as the treatment agent for Example 5 (solid content 2.6% by weight).

[0055] [Example 6] A stock solution of ethylene vinyl acetate copolymer (EVA) aqueous emulsion with a solid content of 21% by weight was diluted 9 times with water to form the treatment agent for Example 6 (solid content 2.3% by weight).

[0056] [Example 7] A stock solution of ethylene vinyl acetate copolymer (EVA) aqueous emulsion with a solid content of 21% by weight was diluted 10 times with water to serve as the treatment agent for Example 7 (solid content 2.1% by weight).

[0057] [Example 8] A stock solution of ethylene vinyl acetate copolymer (EVA) aqueous emulsion with a solid content of 21% by weight was diluted 15 times with water to serve as the treatment agent for Example 8 (solid content 1.4% by weight).

[0058] [Comparative Example 1] A CMC aqueous solution, obtained by dissolving carboxymethylcellulose (CMC) in water, was used as the treatment agent for Comparative Example 1 (solid content 0.5% by weight).

[0059] [Comparative Example 2] No treatment chemicals were used.

[0060] [Comparative Example 3] Although no treatment chemicals were used, the soil was compacted.

[0061] The sediment inundation tests and evaluations were carried out according to the following procedures (1) to (7). (1) Make a hole with a radius of 3 cm in the center of a non-permeable plastic board (120 mm x 120 mm), and attach non-woven fabric (repurposed ventilation fan filter) to cover the hole. (2) Place a polyvinyl chloride pipe (inner diameter: approximately 3 cm, height: approximately 10 cm) on a board with the nonwoven fabric side facing up, aligning it with the hole, and place a funnel on top of the polyvinyl chloride pipe. 100 g of recreated soil is then poured in, and the soil is allowed to fall naturally into the polyvinyl chloride pipe. (3) For Examples 1-8 and Comparative Examples 1-2, the polyvinyl chloride pipe is removed upwards as is. This reproduces the state in which an embankment is formed on the board. For Comparative Example 3, the hole in the board is plugged from the opposite side of the polyvinyl chloride pipe, and the area is compacted 25 times with a 2.5 kg rammer before the polyvinyl chloride pipe is removed. (4) Apply the treatment agent from Examples 1 to 8 to the surface of the soil obtained in (3) using a spray bottle at a rate of 1 kg / m². 2 A considerable amount is sprayed and allowed to air dry for about a day in a room with controlled temperature and humidity (temperature: 20±5℃, humidity: 50±10%). For Comparative Example 1, because the viscosity of CMC is high and spraying with a spray bottle is difficult, water is first sprayed onto the surface of the soil, then the treatment agent is sprayed using a syringe, and then allowed to air dry for about a day. For Comparative Example 2, only air drying for about a day is performed. For Comparative Example 3, after compaction (tamping), air drying for about a day is performed. (5) Place each dried sample (soil + plate) on a beaker with the soil side facing up, and then set up a shower 100 mm above it. (6) Spray tap water from the shower in mist mode (flow rate: 1.3 L / min, time: 10 minutes). At this time, the water that permeates through the soil will accumulate in the beaker, and the water that does not permeate through the soil will flow out of the beaker. (7) After the watering is finished, measure the amount of water W (L) that has accumulated in the beaker and calculate the water permeability R (%) using the following formula. Water permeability R(%) = L / 13 × 100 (8) The flood control effect will be comprehensively evaluated based on the permeability R and the condition of the soil. In the case of samples where the soil collapsed before it could withstand 10 minutes of watering, the permeability R cannot be measured, so the flood control effect will be evaluated based on the time until collapse. The evaluation criteria are shown below. ·A + The soil does not collapse for more than 10 minutes, and the permeability is 10% or less. ·A The soil and debris will not collapse for more than 10 minutes. ·B The time it takes for the soil to collapse is 2 to 10 minutes. ·C The time it took for the soil to collapse was less than 2 minutes. ·D The soil collapses instantly (in about 1 second).

[0062] <Test Results> The results of the soil inundation test are shown in Table 2.

[0063] [Table 2]

[0064] <Consideration> As shown in Examples 1-4, when the undiluted ethylene vinyl acetate copolymer (EVA) aqueous emulsion (21% solids by weight) was diluted 2-7 times with water (3.0-10.5% solids by weight) and used as a treatment agent, no collapse occurred in any of the reproduced soils A-C after 10 minutes of continuous watering. Thus, it was found that the treatment agents in Examples 1-4 exhibited excellent flood suppression effects (rating A or higher). In particular, when the treatment agents in Examples 1-3, diluted 2-6 times, were used on reproduced soil A, when the treatment agents in Examples 1-4, diluted 2-7 times, were used on reproduced soil B, and when the treatment agents in Examples 1-4, diluted 2-7 times, were used on reproduced soil C, the permeability was 10% or less, demonstrating an extremely excellent flood suppression effect (rating A). + ).

[0065] As shown in Examples 5-8, when a solution of ethylene vinyl acetate copolymer (EVA) aqueous emulsion (21% solids by weight) diluted 8-15 times with water (1.4-2.6% solids by weight) was used as the treatment agent, none of the reproduced soil samples A-C could withstand 10 minutes of continuous watering. However, since it took more than 2 minutes for them to collapse, a certain degree of flood suppression effect was observed (Evaluation B).

[0066] The results from Examples 1-8 showed that when a treatment agent containing ethylene vinyl acetate copolymer (EVA) was used, the higher the solid content concentration of ethylene vinyl acetate copolymer (EVA) in the treatment agent, the greater the water infiltration suppression effect tended to be. In addition, in the reproduced soil samples A-C, Example 1 (solid content 10.5 wt%), in which the undiluted solution was diluted twice, had a slightly lower water permeability than Example 2 (solid content 4.2 wt%), in which the undiluted solution was diluted five times. This is thought to be because when the solid content concentration of the treatment agent exceeds a certain level, cracks occur in the waterproof layer (EVA layer) formed on the soil surface after drying, and some water penetrates through these cracks.

[0067] In contrast, as shown in Comparative Example 1, when an aqueous solution of carboxymethylcellulose (CMC) (solid content 0.5% by weight) was used as the treatment agent, the soil collapsed in approximately 1 minute for all of the reproduced soils A to C, and no flood suppression effect was observed (Evaluation C).

[0068] As shown in Comparative Example 2, in the cases where no treatment agent was used, the soil collapsed immediately (in about 1 second) in all of the reproduced soils A to C, and no flood suppression effect was observed at all (Evaluation D).

[0069] As shown in Comparative Example 3, in the case where no treatment chemicals were used but the soil was compacted, the soil collapsed in approximately 30 seconds for all of the reproduced soils A to C, and no flood suppression effect was observed (Evaluation C).

[0070] As described above, according to the waste treatment method (example) of the present invention, in addition to the stable storage of waste in the soil due to the weight of the soil (embankment), the thermoplastic resin layer (waterproof layer) formed on the surface of the soil (embankment) prevents or suppresses the infiltration of water into the soil. Therefore, the risk of harmful or toxic substances contained in the waste flowing into the surrounding area due to rainfall or flooding is reduced, and a safe condition can be maintained.

[0071] Incidentally, in Examples 1 to 4, the soil did not collapse, and in Examples 5 to 8, it took a certain amount of time or more for the soil to collapse. Therefore, the waste treatment method of the present invention (examples) can be evaluated as being able to suppress soil collapse to a certain extent or more. Furthermore, even if the soil (embankment) collapses (settles) due to exposure to severe weather conditions such as prolonged heavy rain, the thermoplastic resin layer (waterproof layer) formed on the surface of the soil (embankment) has a certain strength, so the settlement rate of the soil (embankment) is very slow. For this reason, no sudden change in shape occurs on the surface of the embankment, and the waterproof layer of thermoplastic resin formed on the surface of the soil (embankment) is maintained. Accordingly, the waste treatment method of the present invention can prevent ground settlement (collapse) and suppress the accumulation of rainwater on the ground.

[0072] Furthermore, because the soil is not compacted, the waste in the soil is not crushed by pressure, and in this respect, the waste treatment method of the present invention can be said to be highly safe. Moreover, the waste treatment method of the present invention can maintain the shape of the soil sufficiently by the thermoplastic resin layer (waterproof layer) without compacting the soil, and can be said to be highly efficient in that compaction work can be omitted. [Industrial applicability]

[0073] The waste treatment method of the present invention can be used for the purpose of treating various types of waste by burying them in the soil. [Explanation of Symbols]

[0074] 1 ground 2 holes 3. Excavation methods 4. Soil and sand 5. Waste 6. Treatment agents 7 Thermoplastic resin layer (waterproof layer) 8. Chemical tank 9 pumps 10 shower heads 11 Spraying equipment

Claims

1. The excavation process involves digging a hole in the ground where the waste will be buried, A feeding step of putting waste into the aforementioned hole, The burying process involves backfilling the aforementioned hole with soil and sand, A spraying step in which a treatment agent containing a thermoplastic resin is sprayed onto the surface of the backfilled soil, A forming step of forming a waterproof layer of the thermoplastic resin on the surface of the soil and sand. It includes, A method for disposing of waste materials used to form an embankment in the aforementioned burial process.

2. The waste disposal method according to claim 1, wherein the soil and sand are not compacted in the burial process.

3. The waste disposal method according to claim 1, wherein in the burial step, the soil generated in the excavation step is used as the soil to backfill the hole.

4. The waste treatment method according to claim 1, wherein in the spraying step, the content of the thermoplastic resin contained in the treatment agent is 3 to 10.5% by weight.

5. In the aforementioned spraying process, the amount of the treatment agent sprayed is 0.5 kg / m². ２ The waste disposal method according to claim 4.

6. The waste treatment method according to claim 1, wherein in the input step, a superabsorbent polymer is introduced into the hole together with the waste.

7. The waste treatment method according to claim 1, wherein in the spraying step, the thermoplastic resin contained in the treatment agent is ethylene vinyl acetate copolymer (EVA).

8. The waste disposal method according to any one of claims 1 to 7, wherein the waste is animal waste.

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