KR100735030B1 - Artificial soil composition for the greening to use high-temperature melting salt and method of manufacturing the same - Google Patents

Abstract

The present invention relates to an artificial soil composition for greening using hot molten salt, characterized in that it comprises 60 to 70 parts by weight of sewage sludge dry powder, 30 to 40 parts by weight of clay and 10 to 30 parts by weight of hot molten salt.

The present invention can recycle the sewage sludge that is thrown away as waste into an artificial soil composition for greening with high added value, and has an inexpensive effect.

Greening, artificial soil, sewage sludge, clay, molten salt, zeolite

Description

Artificial soil composition for greening using high temperature molten salt and method for manufacturing the same {Artificial soil composition for the greening to use high-temperature melting salt and method of manufacturing the same}

1 is a plant flow diagram of a pilot plant,

2 is a process flowchart of the plant,

3 is a change in density value according to the ratio of sludge and clay,

4 is a comparative photograph of a molded body before foaming (left side drawing) and after (right side drawing),

5 is a graph showing the results of XRD analysis of the prepared specimen,

6 is a comparison picture of the Arabidopsis leaf growth of the general soil (left picture) and the present invention (right picture),

7 is a comparison graph of Arabidopsis leaf production (growth time),

8a is a SEM picture of a flower pot in normal soil,

Figure 8b is a SEM image of a flower pot in the artificial soil composition of the present invention.

The present invention relates to an artificial soil composition for greening and a method of manufacturing the same. More specifically, the present invention relates to an artificial soil composition for greening, in which foamed molded bodies and zeolites are produced by utilizing sewage sludge, and a method of manufacturing the same.

In the 1990s, interest in the environment, such as ecological restoration, has been increasing, and various new technologies and construction methods for artificial soil are being developed. Specifically, in order to restore various ecology such as forests, walls, retaining walls, and roads, it is required to develop technologies such as environmentally friendly artificial soil materials and restoration methods.

In the case of roads, the road slopes, which make up a large part of the greening area, were mainly constructed by the green soil method. However, due to the recent increase in costs, natural topsoil restoration methods that directly mix and process wood chips and natural topsoil generated in the field with polymers and organic materials are recommended, or texol method mixed with long fibers, and excellent permeability are secured. Artificial soil improvement method for the construction is being installed as a mounting method.

On the other hand, from the 2000s, the focus is on the development of 3G advanced ecological restoration and regeneration technology centered on environment-friendly low cost technology. In particular, research and development are being actively conducted to enhance the self-cleaning ability of nature and restore eco-friendliness.

In Japan, natural topsoil technology and forestry technology using artificial soil are typically used. This technology uses the characteristics of natural soils, and it is a method of making artificial soils in areas where natural soils are damaged due to development activities so that organisms can inhabit.

New techniques in advanced environmental restoration are particularly predominantly forested. This induces the restoration of the ecosystem by growing plants from seeds, not from planting, and is constructed using artificial soil. This is an environmentally friendly method similar to the surroundings, allowing the growth of woody plants, rather than the introduction of herbaceous plants.

    Recently, the development of artificial ground greening materials using waste vinyl chloride, waste wood chips, etc., is in progress. Many eco-friendly concrete materials that plants can live in concrete and cement have been tried. The development of a vegetable artificial island material is also in progress.

In Europe, the rooftop recording system has reached a considerable level, and other artificial grounds (parking lots, roadsides, etc.) are also being promoted to expand the greening area of more than 7 million m ² . In recent years, excellent treatment has been achieved by utilizing the drainage technology. In addition, it is developing and distributing lightweight restoration materials and cylindrical ecological blocks cured using waste materials and coal ash.

    In Switzerland, as a basic policy, many small stream treatment plants are constructed around rivers to prevent dry weather. In addition, biological river maintenance technology and the rafting technology using stone or concrete materials have been developed and spread.

   In France, Texol technology, which is a continuous long fiber reinforcement method using a polyester resin, is used.

In the United States, in the mid-1980s, a superfund program was established to restore ecological and polluted areas. In practice, however, the technology applied to the site by 2000 is limited.

    Heilated Iron SOIL CONDITIONER-ORGANIC and Utelite E-Soil (Soil Conditioner) are developed and commercialized as soil improving agents. These soil modifiers also have advantages, but they have a common disadvantage that they are expensive to use in large quantities.

An object of the present invention is to produce a foamed molded article and zeolite from sewage sludge using hot molten salt to produce an artificial soil composition for greening that can grow plants. This aims to promote efficient and economical recycling of sewage sludge.

Artificial soil composition for greening using the hot molten salt of the present invention is characterized in that it comprises 60 to 70 parts by weight of sewage sludge dry powder, 30 to 40 parts by weight of clay and 10 to 30 parts by weight of hot molten salt.

The hot molten salt of the present invention is characterized in that any one or more selected from the group consisting of KCl, KF, KI, NaCl, Nal, Na ₂ SO ₄ , CaCl ₂ , Cal ₂ , MgCl ₂ and Mgl ₂ .

 Method for producing artificial soil composition for greening using the hot molten salt of the present invention, the step of drying the sewage sludge; Forming a composition comprising 60 to 70 parts by weight of sewage sludge dry powder, 30 to 40 parts by weight of clay, and 10 to 30 parts by weight of hot molten salt; And a calcining step in which the molded body is heat treated.

The present invention will be described in more detail below.

Sewage sludge contains several chemical components as shown in Table 1 below.

Sample (wt%) Sewage sludge Winter season Summer season Na ₂ O 0.64 0.71 MgO 1.75 1.96 Al ₂ O ₃ 17.10 15.80 SiO ₂ 31.19 32.34 P ₂ O ₅ 14.14 12.8 SO ₃ 10.30 11.11 Cl 0.25 0.26 K ₂ O 2.60 3.1 CaO 12.00 10.64 TiO ₂ 0.81 0.91 MnO 0.84 0.54 Fe ₂ O ₃ 7.23 8.58 NiO 0.04 0.01 CuO 0.3 0.13 ZnO 0.63 0.43 TOTAL 99.19 98.89

Various inorganic components _such as SiO _{2 and} Al ₂ O ₃ contained in sewage sludge facilitate the formation of zeolites.

Zeolites are aluminum hydrous silicate minerals containing alkali earth metals such as alkali metals and calcium and having water in the form of crystal water, also called 'boiling stones', or zeolites. .

Zeolites are characterized by molecular sieve, polar adsorption, catalysis, cation substitution capacity (CEC) and high content of phosphoric acid and silicic acid. Due to these characteristics, zeolites are used for various purposes such as agriculture for soil improving agents, fertilizer mixtures, green management for lawn landscaping, and special crops for ginseng, tobacco, horticulture.

The present invention intends to easily generate zeolite using various inorganic components contained in sewage sludge. As a result of analyzing the properties of sewage sludge dry powder, there is no specificity of components due to seasonal changes and it has good conditions for the synthesis of zeolite as SiO ₂ / Al ₂ O ₃ ≒ 2. And it is preferable that the moisture content of the sewage sludge dry powder of this invention is about 60 to 80%.

Generally, zeolite is synthesized by mixing a salt such as NaOH with water at about 100 ° C. to dissolve it, mixing the sludge, and eluting Si and Al in the sludge to crystallize it.

Here NaOH serves to elute Si and Al, since the salt such as NaOH is dissolved at a low temperature can react in aqueous solution.

However, since the temperature of the present invention is a high temperature of 1000 ℃ or more, there is a need for a salt that can serve as NaOH at high temperatures. The hot molten salt added after mixing sewage sludge and clay is melted at a high temperature and plays the same role as NaOH. Since the injected temperature is high around 1000 ° C., the material melted below this temperature range is used.

The clay is also mixed with the sewage sludge, making it easy to produce shaped bodies having a certain shape. As the clay used in the present invention, various kinds of clays such as montmorillonite, bentonite, and illite may be used. And it is preferable to use an illite clay from the viewpoint of the foaming of a molded object.

The artificial soil composition using the hot molten salt of the present invention preferably contains 60 to 70 parts by weight of sewage sludge dry powder, 30 to 40 parts by weight of clay and 10 to 30 parts by weight of the hot molten salt.

In addition, the artificial soil composition using the hot molten salt of the present invention, it is also preferred that 10 to 30 parts by weight of the hot molten salt is added to the composition containing 60 to 70 parts by weight of sewage sludge dry powder and 30 to 40 parts by weight of clay.

Hereinafter, the invention of the manufacturing method of the artificial soil composition for greening will be described.

1 is a flow chart of the installation of a pilot plant, and FIG. 2 is a process flowchart of the plant.

The production method of the present invention, the step of drying the sewage sludge; Forming a composition comprising 60 to 70 parts by weight of sewage sludge dry powder, 30 to 40 parts by weight of clay, and 10 to 30 parts by weight of hot molten salt; And a firing step in which the molded body is heat treated.

In the drying step of the sewage sludge, the water content is preferably about 60 to 80%. Excessive drying costs can be a problem if the sewage sludge is dried below 60% water content. However, when the moisture content is dried at 60 to 80%, an appropriate drying cost is possible, and there is an advantage of easily operating the drying process. In addition, there is an advantage that does not need to add a water to act as a binder when producing a molded article.

In the case of sewage sludge, there is a problem that the density value is increased if it is less than 60 parts by weight, and when it exceeds 70 parts by weight, it is difficult to produce a molded article and there is a problem of melting in the firing step. Therefore, about 60-70 weight part is preferable.

Next, the clay and hot molten salt are mixed with the dried sewage sludge dried powder.

If 30 to 40 parts by weight of clay is added, it is mixed with sewage sludge to facilitate the production of shaped bodies having a certain shape. As the clay used in the present invention, various kinds of clays such as montmorillonite, bentonite, and illite may be used.

When mixing the sewage sludge dry powder and clay first, it is preferable to further mix the appropriate amount of hot molten salt according to the component ratio of the mixed composition to produce a molded article.

This is because the mixing ratio of hot molten salt should be calculated according to the mixing ratio of sewage sludge dry powder and clay.

In order to synthesize zeolite from sewage sludge, the elution of Si and Al is required. When the sewage sludge and clay are mixed, the component ratios of Si and Al vary depending on the mixing ratio. In addition, the component ratios of Si and Al contained in the sewage sludge itself vary depending on the generation region or season of the sewage sludge.

 Therefore, by calculating the ratio of the salt in accordance with the content ratio of Si and Al, the appropriate amount of hot molten salt is determined.

When the hot molten salt is added 10 to 30 parts by weight, it is easy to dissolve Si and Al in the sewage sludge component during zeolite synthesis.

The hot molten salt used in the present invention is preferably at least one selected from the group consisting of KCl, KF, KI, NaCl, Nal, Na ₂ SO ₄ , CaCl ₂ , Cal ₂ , MgCl ₂ and Mgl ₂ . When the metal salt made of ionic crystals is heated and melted, it becomes a molten salt which is a liquid having low viscosity, high conductivity and easy movement of ions.

In this invention, it is preferable to mix 60-70 weight part of sewage sludge dry powders, 30-40 weight part of clays, and 10-30 weight part of hot molten salts.

Moreover, it is preferable to add and mix 10-30 weight part of hot molten salts to the composition containing 60-70 weight part of sewage sludge dry powders, and 30-40 weight part of clays.

The clay used in the present invention may be of various kinds, but it is preferable that the illite clay is preferable in view of ease of foaming.

Illite is a fine mica mineral belonging to the monoclinic system. Illite clay is used to improve the formability of the artificial soil composition, thereby increasing the mass production and utility.

Next, a step of forming a composition of sewage sludge, hot molten salt and clay is mixed.

The molded article of the composition can be produced in various shapes as needed. In particular, the pellet-formed product has a feature that is easy to mass-produce, and when 30 to 40 parts by weight of high viscosity elite clay is added, the pellet-formed product is easily formed.

Next, the molded body of a predetermined shape is subjected to the step of firing through heat treatment. The heat treatment apparatus may be a conventional apparatus such as a rotary kiln.

Since the temperature at which the organic matter contained in the sewage sludge is pyrolyzed is about 550 ° C, when the molded product is put at 1000 ° C or more, the outside becomes vitrified to show a partial molten state. As the oxide decomposes, it releases gases such as CO ₂ , CO, and SO ₂ .

That is, since it is pyrolyzed at about 550 ° C., heat treatment at a much higher temperature results in relatively faster pyrolysis, thereby facilitating foaming. At this time, the foaming is made at the same time as the formation of the micropores.

The molded body before the heat treatment contains clay, for example, an elite clay. Since the melting point of the clay is about 1000 ° C, foaming and micropores are first formed by pyrolysis and secondly, the exterior of the molded body is melted. .

When the molded body is put into the rotary kiln, as the internal material is thermally decomposed, the molded body swells and the pyrolyzed gases exit the molded body. In this process, fine pores are formed and foaming is performed.

The advantage of foaming formed through this process is that micropores are formed. The micropores can absorb moisture and other ingredients into the micropores by capillary force, and the absorbed moisture and nutrients are gradually released to the artificial soil. It has the characteristics to provide the necessary elements on an ongoing basis.

On the other hand, zeolite is characterized by high CEC value. When the product is used as artificial soil, the soil that plays a big role in plant growth is the bore force and cation. The substitution ability will have excellent characteristics.

The melting temperature of the high temperature molten salt is about 600 ~ 800 ℃, the ions can be moved when the molten state, and the molded body can be fired. Therefore, as for the baking temperature of this invention, about 600-800 degreeC is preferable.

And the heat treatment should be performed for about 0.5 to 3 hours to form the zeolite in the molten state, the clay may be sintered to produce the product in the form of granules. Therefore, the firing time of the present invention is preferably about 0.5 to 3 hours.

<Test Example 1>

When the sewage sludge was tested at 60 parts by weight, the density value was the lowest, and when the sewage sludge was added at 50 parts by weight or less, the density value was increased. (Refer to FIG. 3 which shows the change of density value according to the sewage sludge and clay ratio.) If the amount of sewage sludge is high, the density value is lowered due to the influence of microorganisms, etc. It is difficult and it is judged to be unsuitable because it shows melting phenomenon in the firing step.

4 is a comparative photograph of the molded body before and after foaming, and FIG. 5 is a graph showing the XRD analysis results of the prepared specimen. XRD test means X-ray diffraction test.

Actually tested under the conditions of 60 parts by weight of sewage sludge, 25 parts by weight of hot molten salt, 40 parts by weight of illite clay, it can be seen that the foaming of the molded body as shown in Figure 4 well, the mineral phase analysis of the Sodalite form It can be seen that the zeolite has been synthesized.

Look at the performance of the artificial soil composition for greening using the hot molten salt of the present invention.

Table 2 shows the zeolite characteristics of the artificial soil of the present invention. Compared with the components of general zeolites, the BET value is equal to or higher and less than 50% of the CEC value, but the artificial soil is 40 or less when compared to the CEC value of the soil. It can be used as soil, and it is a weak alkali that is suitable for vegetation.

Analysis item (unit) CEC (cmol / kg) BET (㎡ / g) pH Analysis 56 86 8.78-8.92

Table 3 shows the characteristics of artificial soil by particle size. It can be seen that the present invention is a weak alkali suitable for plant growth.

 Analysis item (unit) Analysis A (2 mm or less) B (2-5 mm) C (more than 5mm) Specific gravity (g / cm ³ ) 0.75 0.61 0.55 pH [1: 5] 8.78 8.62 8.92 Burning loss (%) 0.30 0.85 0.91 moisture(%) 0.11 0.18 0.15 Volatile fraction (%) 0.09 0.31 0.47 Ash content (%) 99.81 99.51 99.38 Ca (mg / kg) 6825.0 7925.0 9245.0 Mn (mg / kg) 90.5 42.0 45.0 Pb (mg / kg) 1.2 1.5 0.8 Cu (mg / kg) 66.0 91.5 105.0 Mo (mg / kg) 7.0 5.0 8.5 Fe (mg / kg) 429.0 571.0 829.0

Meanwhile, the mouse cress is a biennial plant of the Cruciferaceae, and its scientific name is Arabidopsis thaliana. It is 15-35cm high. Root leaves gathered and inverted lanceolate, stem leaves without lanceolate in lanceolate. Small white flowers bloom from the end of stem in April-May. The fruit is a nut.

 Arabidopsis germination and the first generation period until the next seed is about 6 weeks short, using chemicals can easily create a variety of mutants. Its small size makes it easy to grow in glass containers and the genome is small. For this reason, it is widely used as a model plant for plant research.

Arabidopsis was used for the testing of the present invention. Figure 6 is a comparison of the leaf growth of the Arabidopsis cultivated with the artificial soil composition of the present invention, Figure 7 is a comparison graph of the leaf generation number of the Arabidopsis, Figure 8a is a SEM picture of a flower pot in ordinary soil, Figure 8b artificial SEM picture of flower pots in soil composition.

Compared to general soils, the rate of growth and the growth rate of the foliar leaves are equal or better. In addition, it can be seen that the growth of pollen water, lipids, etc., which are structural features of the pollen, are good.

According to the present invention, foaming and zeolite are produced from sewage sludge using high temperature molten salt, so that the adsorption capacity and cation substitution ability by micropores can be effectively improved. As a result, the sewage sludge disposed of as waste can be recycled into a high value-added artificial soil composition for greening, and the cost is low.

Claims (9)

It is produced by mixing and molding a composition comprising 60 to 70 parts by weight of sewage sludge dry powder having a water content of 60 to 80%, 30 to 40 parts by weight of clay, and 10 to 30 parts by weight of hot molten salt, and then calcining. doing Artificial soil composition for greening using high temperature molten salt. The method of claim 1, The clay is characterized in that the illite clay Artificial soil composition for greening using high temperature molten salt. The method of claim 1, The high-temperature molten salt, KCl, KF, KI, NaCl, Nal, Na ₂ SO _4, CaCl _2, Cal _2, MgCl ₂ and Mgl, characterized in that at least one selected from the group consisting of _2, Artificial soil composition for greening using high temperature molten salt. Drying the sewage sludge such that the water content is 60 to 80%; Mixing and molding a composition comprising 60 to 70 parts by weight of sewage sludge dry powder, 30 to 40 parts by weight of clay, and 10 to 30 parts by weight of hot molten salt; And Characterized in that it comprises a firing step in which the molded body is heat treated. Method for producing artificial soil composition for greening using high temperature molten salt. The method of claim 4, wherein The clay is characterized in that the illite clay Method for producing artificial soil composition for greening using high temperature molten salt. delete The method of claim 4, wherein The hot molten salt of the mixing step is any one or more selected from the group consisting of KCl, KF, KI, NaCl, Nal, Na ₂ SO ₄ , CaCl ₂ , Cal ₂ , MgCl ₂ and Mgl ₂ Method for producing artificial soil composition for greening using high temperature molten salt. The method of claim 4, wherein The firing step is characterized in that the progress in the temperature range of 600 ~ 800 ℃ Method for producing artificial soil composition for greening using high temperature molten salt. The method of claim 4, wherein The firing step is characterized in that for about 0.5 to 3 hours Method for producing artificial soil composition for greening using high temperature molten salt.

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