Method for producing planting soil

Abstract

To provide a method for producing planting soil, by which high-quality planting soil can be produced in a low environmental load.SOLUTION: In the method for producing the planting soil 14, dehydrated soil 20 is produced by adding a carbonized material 19 to soil 12 generated in a water purification plant to dehydrate the soil 12, and the planting soil 14 is produced by mixing and stirring improved soil 13 produced from construction sludge and the dehydrated soil 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing planting soil. [Background technology]

[0002] Traditionally, water purification plants add aluminum salts such as PAC (polyaluminum chloride) as an inorganic coagulant to raw water to coagulate and precipitate organic and inorganic matter contained in the water, and then recover the resulting soil. Because a large amount of this soil is generated, it is desirable to recycle it as a soil resource to reduce treatment costs and environmental impact. However, water purification plant soil not only hardens after drying due to the aluminum in the coagulant, but also becomes acidic due to the pH buffering ability of amorphous aluminum hydroxide, and has a high phosphate absorption coefficient. Therefore, in order to use it as planting soil, the soil quality must be improved by adding organic matter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4810260 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a method for producing high-quality planting soil with low environmental impact. [Means for solving the problem]

[0005] The method for producing planting soil of the present invention involves adding a carbonizing material to soil generated at a water purification plant to dehydrate it and produce dehydrated soil, and then mixing and stirring the dehydrated soil with improved soil produced from construction sludge to produce planting soil. [Effects of the Invention]

[0006] According to the present invention, high-quality planting soil can be produced with low environmental impact. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram showing a method for producing planting soil according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present invention will now be described with reference to FIG.

[0009] 1 shows a manufacturing system 10. The manufacturing system 10 is a manufacturing system that uses water purification plant generated soil 12 and improved soil 13 as raw materials to manufacture planting soil 14 such as gardening soil or field soil.

[0010] The water purification plant generated soil 12 is a recycled material made from organic and inorganic matter contained in raw water, such as river water, obtained at the water purification plant, and is produced by adding an inorganic coagulant to the raw water to cause the organic and inorganic matter to coagulate and settle. The inorganic coagulant may be, for example, an aluminum salt, e.g., PAC (polyaluminum chloride). In this embodiment, the water purification plant generated soil 12 is the soil that has not yet been dehydrated and dried, and is in the form of a slurry containing a large amount of water, and is transported from the settling basin 15 of the water purification plant.

[0011] The improved soil 13 is a recycled material produced by subjecting construction sludge in a slurry state to processes such as sorting, mixing with a solidifying agent, and classification. Lime, for example, is used as the solidifying agent. A vibrating sieve, such as a multi-stage (three stages in the figure) vibrating screen 17, is used as the classification means. The vibrating screen 17 shown in the figure is configured with coarse, medium, and fine screens 17a, 17b, and 17c, respectively, arranged at an angle, and the screens 17a, 17b, and the screens 17b, 17c, are connected by conveyors 17d, 17e. In this embodiment, improved soil 13 with a particle size of 3 mm to 5 mm, which has been classified through the fine screen 17c, for example, is used. The improved soil 13 is alkaline soil, for example, with a pH of about 10.

[0012] When producing planting soil 14, first, the discharged water purification plant generated soil 12 is placed in a treatment tank 18, and carbonized material 19 is added to the treatment tank 18 and stirred to dehydrate the water purification plant generated soil 12, producing dehydrated soil 20, an intermediate product (dehydration process). In this embodiment, the carbonized material 19 is a recycled material, such as paper sludge, carbonized in a carbonization furnace, and formed into pellets or powder. The water purification plant generated soil 12 and the carbonized material 19 are mixed at a predetermined ratio, for example, adding 10% to 30% of the carbonized material 19 based on the weight of the water purification plant generated soil 12. The water purification plant generated soil 12 and the carbonized material 19 are mixed and stirred using, for example, mechanical stirring or construction machinery such as a backhoe. The dehydrated soil 20 is acidic soil with a pH of approximately 6, reflecting the pH value of an inorganic flocculant, such as amorphous aluminum hydroxide (PAC), which flocculates the organic and inorganic matter constituting the raw water purification plant generated soil 12.

[0013] Next, the improved soil 13 and the dewatered soil 20 are mixed and stirred to obtain the planting soil 14, a product with improved soil quality (mixing and stirring process). The improved soil 13 and the dewatered soil 20 are mixed at a predetermined ratio. This predetermined ratio may be set arbitrarily depending on the pH values ​​of the improved soil 13 and the dewatered soil 20 and the desired soil quality of the planting soil 14, but for example, the weight ratio of the improved soil 13 to the dewatered soil 20 is set to 1:3 to 1:5. The improved soil 13 and the dewatered soil 20 are mixed and stirred, for example, by mechanical stirring. In the figure, the mixing means, the mixing and stirring device 22, is shown as a horizontal type. This mixing and stirring device 22 has a rotor 26 with multiple stirring claws 25 protruding from the outer periphery of a rotating shaft 24, which is supported inside a long cylindrical casing 27, and as the rotor 26 rotates, improved soil 13 and dewatered soil 20 are added from one end of the casing 27 and stirred, and then discharged as planting soil 14 from the other end.

[0014] The planting soil 14 produced in this manner is unsolidified, has a granular, loose texture, and is neutral soil with a pH adjusted according to the pH values ​​of the improved soil 13 and the dehydrated soil 20. The planting soil 14 does not generally require the addition of fertilizers (nitrogen, phosphate, potassium), but may be mixed with, for example, dried eggshells and / or chicken manure.

[0015] As described above, according to one embodiment, water purification plant generated soil 12 is dehydrated by adding carbonized material 19 to produce dehydrated soil 20, and improved soil 13 produced from construction sludge is mixed and stirred with the dehydrated soil 20 in a predetermined ratio to produce planting soil 14, thereby making it possible to produce high-quality planting soil 14 with low environmental impact.

[0016] Furthermore, since the dehydrated soil 20 and the improved soil 13 are dry raw materials, no special manufacturing machinery is required, and they can be manufactured using various mixing means other than the above-mentioned mixing and stirring device 22.

[0017] Since there is no need to use expensive equipment such as a filter press when dewatering the soil 12 generated at the water purification plant, it can be produced at low cost.

[0018] Furthermore, there is no need to consider temperature, humidity, time, climate, weather, etc. in the dehydration process and mixing and stirring process, and the planting soil 14 can be easily produced by a simple process that basically involves only mixing and stirring.

[0019] By setting the particle size of the improved soil 13 to 3 mm to 5 mm, the improved soil 13 and the dewatered soil 20 can be efficiently mixed and stirred in the mixing and stirring step.

[0020] Carbonized material 19 is produced by carbonizing paper sludge and does not produce ash or carbon dioxide during production, so using this carbonized material 19 contributes to reducing carbon dioxide emissions. In addition, the water purification plant generated soil 12, improved soil 13, and carbonized material 19, which are the raw materials used to produce planting soil 14, are all recycled materials, which reduces waste, conserves resources, and has an extremely small environmental impact.

[0021] Although the embodiment of the present invention and its modified examples have been described above, various combinations of configurations, partial omissions, substitutions and modifications are also possible. [Explanation of symbols]

[0022] 12. Water purification plant soil 13 Improved Soil 14 Planting soil 19 carbonized materials 20 Dehydrated soil

Claims

1. Dehydrated soil is produced by adding carbonized material to the soil generated at the water purification plant. Planting soil is produced by mixing and stirring the improved soil produced from construction sludge with the dehydrated soil. A method for producing planting soil, comprising:

2. The improved soil has a particle size of 3 mm to 5 mm.

2. The method for producing planting soil according to claim 1.

3. The carbonized material is made by carbonizing paper sludge.

3. The method for producing planting soil according to claim 1 or 2.

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