JP3828737B2 - Planting soil and its manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a treated soil obtained by the same method as a method for modifying soil such as construction sludge. The treated soil obtained by this method is agglomerated and does not re-mud, so it has little impact on the environment, and because it has excellent water retention, it can be effectively used as planting soil. .
[0002]
[Prior art]
Soil is an aggregate of grains with relatively small particle size, mainly made by the weathering action of rocks. In soil engineering, “soil” contains all the materials that make up the ground. The size of the particles is wide, and the materials of the materials include various kinds from pure minerals to industrial waste. For example, construction sludge, dredged landfills modified with solidified materials such as sludge and cement deposited in rivers, lakes, canals, and sea areas with high organic matter content are included. Therefore, its behavior is extremely complex and varied.
[0003]
Even in the soil described above, construction sludge exhibits a high water content, and the soil originally forming the ground often becomes mud in the course of construction work, and examples containing harmful substances are extremely rare.
[0004]
[Problems to be solved by the invention]
Construction sludge is excavation sludge or fine mud soil that is generated during construction work, and cannot be directly used for embankment. For this reason, with the exception of what is currently being partially reused, most of it is dewatered at intermediate treatment facilities as “sludge”, which is industrial waste, or directly brought to the final disposal site. However, dewatering work requires a large amount of equipment and costs including water treatment facilities, and work requires a large area of land. For this reason, there has been a demand for a simple method capable of treating construction sludge without dehydration and recycling it.
The same applies to the generated soil (high water content mud) generated in the process of water purification at the water purification plant.
[0005]
An object of this invention is to provide the recycling method which can process the soil of high moisture content like construction sludge, purified water sludge, etc., and can use it for another effective use.
[0006]
[Means for Solving the Problems]
The method for producing a planting soil according to claim 1 is characterized by adding a mechanical shear stress by adding waste paper and acrylic polymer having a thickness of 0.1 mm or less and a thickness of 0.1 cm or less to sludge having a high water content ratio. Applying dynamic pressure and rotational motion to the sludge to lower the porosity, shortening the distance between the soil particles, generating stickiness due to the increase in the bonding force between the soil particles, and consolidating the sludge in a state where moisture is confined inside It is characterized by granulation.
[0007]
The planting soil described in claim 2 is moved to the sludge by adding mechanical shear stress by adding waste paper and acrylic polymer having a thickness of 0.1 cm or less and a thickness of 0.1 mm or less to sludge having a high water content ratio. Applying pressure and rotational motion to lower the porosity, shortening the distance between the soil particles, generating stickiness due to the increase in the bonding force between the soil particles and aggregating the sludge in a state where moisture is confined inside It is a thing.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The manufacturing method of the planting soil which concerns on this invention is demonstrated.
Put construction sludge into the storage tank. A piece of waste paper as fibrous material is put into the mud storage tank and stirred. Used newspaper wastepaper absorbs free water in the sludge. Add polymer agglomerate into the mud storage tank and stir.
The water-soluble polymer reacts with the adsorbed water on the surface of the mud particles, and the particles are bonded by the crosslinking action.
Next, when a mechanical shear stress is applied, a aggregated state is obtained.
[0009]
Examples of the polymer improver used in the above-described examples include polyacrylic acid, polyacrylate, polyacrylate ester, polyacrylamide, a copolymer obtained by a combination thereof, and polyacrylic acid, which are conventionally known as soil improvers. Various types such as alkylene glycol, maleic anhydride, a copolymer with an epoxy compound and the like are considered, and water-soluble polymers are particularly preferable. For example, synthetic water-soluble polymer powder (PH7-8, moisture 10 ± 2%, bulk specific gravity 0.6-0.7, true specific gravity 1.4-1.5) etc. with polyacrylic polymer as the main component is used it can. These polymer improving materials are preferably added at a rate of 1 kg or more per 1 m ³ of the target soil.
[0010]
Further, as the fibrous material, various kinds of natural or synthetic materials can be used in addition to the above-mentioned used newspaper paper. About these fibrous substances, the shape may be various shapes such as a strip shape, a small piece shape, a thread shape and a cloth shape. Can be added as The amount added can be appropriately determined experimentally according to the type and properties of the target soil so that the synergistic effect with the amount added of the polymer-based improving material becomes large. For example, the amount added is preferably about 30 kg to 90 kg in the case of waste paper with respect to 1 m ³ of the target soil. Furthermore, in the case of a high water content sludge, 100 kg or more is required.
[0011]
In the above process, when a mechanical shear stress is applied to the soil by means such as stirring after adding the fibrous substance and the polymer-based improving material to the soil, the soil aggregates as described above. The characteristics of the soil are controlled in such a way that they are hard to break and sticky.
In general, when a mechanical shear stress such as agitation is applied to improved soil having a high uniaxial compressive strength, it becomes crushed. In the case of improved soil with low uniaxial compressive strength, it becomes a paste.
Thus, it has been considered difficult to aggregate the improved soil.
However, in the present invention, an appropriate compressive strength and a large fracture strain can be obtained by performing an operation such as adding a fibrous substance and a polymer-based improving material. And if the dynamic pressure and rotational motion by a mechanical shear stress are given, the process soil which has a big compressive-strain stress will reduce the porosity. That is, the decrease in the porosity means that the distance between the particles constituting the treated soil is shortened. As a result, the stickiness due to the increase in the bonding force between the particles is generated and the agglomeration becomes possible.
[0012]
Conventionally, a solidification process in which a solidification material is added to construction sludge has been known, but this method required crushing and occasionally loosening the solidified sludge, but the soil obtained in this example was aggregated from the beginning. Because there is no need to crush and loosen. Of course, it is not necessary to remove moisture with a press unlike conventional construction sludge. In this state, it can be loaded onto a dump truck and taken out. In other words, since no curing time is required, no temporary storage is required.
[0013]
In addition, the soil obtained in this example is excellent in water retention and is useful as planting soil.
The soil A of this example was compared with the other soils B and C. B is a base material soil for slope greening spraying. C is general gardening soil. The water content of each soil is different. Prepare a litter lump for each soil A-C. Each lump of soil was immersed in the water of a separate storage tank for a predetermined time. When the weight of each soil lump taken out from the water was measured, the soil lump of this example was 1.7 kg, B was 1.3 kg, and C was 1.1 kg.
[0014]
These soil clumps were left outdoors where they were not exposed to direct sunlight, and their daily changes in weight were measured. The results are shown in FIG. The soil A of this example contained the most water, and it took a long period of about 30 days for the water to gradually evaporate and settle down to a constant weight, and the evaporation of the water almost stopped. The amount of moisture released during this period is represented by a shown in FIG. In comparison, soil B had approximately 10 days before the evaporation of water stopped, and the amount of water released during this period was b shown in FIG. Soil C was approximately 5 days before the evaporation of moisture stopped, and the amount of moisture released during this period was c shown in FIG. As is clear from the figure, a> b, c.
[0015]
Thus, according to the soil of this example, the water retention is better than other soils. That is, the soil of this example has a large amount of water retention and a long water retention period. Therefore, if the soil of this example is used as planting soil, the plant can germinate and grow properly even if watering frequency is low. An experiment was conducted in which the same amount of the soil of this example and the other soil were placed in a pot, seeded with Komatsu rapeseed, and watered under the same conditions. As a result, on the 15th day, Komatsuna grew on the entire surface of the soil of this example, whereas in other examples no germination was observed.
[0016]
Thus, since the soil of this example is agglomerated in a state where moisture is confined inside, it is difficult to melt even if it contacts external water, and even if immersed in the water of the storage tank in the above experiment, The water did not become cloudy. Therefore, even if the soil of this example is used as planting soil in a park or the like, there is no risk that the soil will melt and contaminate the environment when it rains.
[0017]
Furthermore, in view of the characteristics of the soil of this example as described above, it can be used not only as a planting soil used in parks and the like, but also as a slope greening base material and a rooftop greening base material. It can also be used actively to restore devastated nature and farmland. For example, when a forest or cultivated land is covered with a mud flow of volcanic ash due to volcanic activity, etc. In addition, there is no risk of runoff due to rainfall, etc., and vegetation recovery can be expected to proceed smoothly due to high water retention. The present invention is also effective as a countermeasure against the red water problem that is a problem in Okinawa and the like, that is, the problem that the red soil of the mountain flows into the sea together with rainwater and pollutes the sea area.
[0018]
【The invention's effect】
According to the planting soil and the method for producing the same according to the present invention, by adding a fibrous substance and a polymer-based improving material to construction sludge and stirring, the soil is agglomerated and water retention is improved. Therefore, it is possible to recycle the construction sludge, which has been conventionally treated as an industrial waste at a high cost, as planting soil for a wide range of useful uses at a low cost.
[Brief description of the drawings]
FIG. 1 is a diagram showing experimental results comparing water retention between soil treated according to the present invention and other soil.

Claims (2)

By adding old paper and acrylic polymer with a thickness of 0.1 mm or less to sludge with a high water content to a thickness of 0.1 mm or less and applying mechanical shear stress, the sludge is given dynamic pressure and rotational motion to reduce the porosity. A method for producing planted soil, characterized in that the sludge is agglomerated in a state in which the distance between the soil particles is shortened to cause stickiness due to an increase in the bonding force between the soil particles and moisture is confined inside . By adding old paper and acrylic polymer with a thickness of 0.1 mm or less to sludge with a high water content to a thickness of 0.1 mm or less and applying mechanical shear stress, the sludge is given dynamic pressure and rotational motion to reduce the porosity. Planted soil in which the sludge is agglomerated in a state in which the distance between the soil particles is shortened to cause stickiness due to the increase in the bonding force between the soil particles and moisture is confined inside .

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