KR100992505B1 - Contaminated Soil Restoration Method using inorganic porous matter - Google Patents

Abstract

Disclosed is a method for restoring contaminated soil using an inorganic porous body according to the present invention.

The present invention, by activating the microorganisms having the ability to decompose pollutants to produce carbon (C: Carbon), nitrogen (N: nitrogen), phosphorus (P: phosphorus) and the inorganic porous body on which the microorganisms are carried, It is a contaminated soil restoration method characterized by biologically decomposing pollutants of contaminated soil by mixing the inorganic porous body and contaminated soil.

According to the present invention, in order to solve the problem that the restoration of the contaminated soil takes a long time when using the existing biological method, the contaminated soil restoration period is shortened by using the inorganic porous body loaded with microorganisms.

Contaminated soil, contaminated soil restoration, microorganisms, porous bodies, mixed porous bodies.

Description

Contaminated Soil Restoration Method using inorganic porous matter

The present invention relates to a method for restoring contaminated soil using microorganisms to decompose harmful substances, and more particularly, to restore contaminated soil such as oil by culturing microorganisms at high concentrations and mixing inorganic porous bodies carrying high concentration microorganisms with contaminated soils. It's about how to do it.

As industrial development and urbanization progress, various harmful components including toxic heavy metal elements are artificially produced and discharged, and they are distributed to the global chemical environment including the atmosphere, water, and soil through mobile media such as natural water and air. Therefore, it can potentially cause fatal damage to organic life including humans.

The most common contaminants affecting soil pollution are heavy metals, oil-related products, PAH and PCB systems. Pb, Cr, As, Cd, and Zn are most frequently found in contaminated areas. Trichloroethylene, PCB, Tertrochloroethylene, Benzene, and Trichloroethane are the dominant species. The treatment of soil contaminated by these pollutants can be performed in-situ or ex-situ, but economic factors are an important issue in each case. Looking at the treatment method, Bioremediation is a method that decomposes harmful substances by using microorganisms and finally converts them into CO ₂ and water. Promote In general, the biological treatment method has a long treatment time disadvantage, but the product after the reaction has a biologically beneficial advantage.

Chemical treatment is a method of stabilizing contaminants by injecting chemicals into contaminated soil. This method is applicable to contaminated soil sites, but has the disadvantage of damaging biological control of soil by adding chemicals.

Thermal treatment is a method to remove highly volatile organic contaminants by applying heat within a temperature not exceeding 600 ° C. Thermal treatment is mainly performed using rotary kiln. The disadvantage is that the soil is biologically dead.

Vacuum-extraction is a method to volatilize contaminants by treating the contaminated soil in a vacuum. This method is widely used to treat contaminated soil, especially near auto repair shops, contaminated with fuel or oil.

Vitrification is a method of vitrifying soil by treating contaminated soil at high temperature (maximum treatment temperature 1600 ℃). Although it can be applied when several treatment methods are not feasible, the energy consumption is very large and expensive.

Electrokinetic extraction is the movement and extraction of contaminants in soil and groundwater using electrokinetic phenomena such as electroosmotic and electro-ion transport induced by currents supplied to soil and groundwater. When applied to the soil, groundwater in the soil is moved to the cathode by electroosmosis, and at this time, the conditions that are applicable to the technique using the phenomenon of simultaneously adsorbing the soil or existing in the pore water also have limitations. .

In the present invention, as a method for restoring soil contamination using microorganisms among the various methods, the inorganic porous body carrying microorganisms having pollution decomposing ability is minimized to minimize the long-term pollution restoration period, and the most effective application conditions are formed. It suggests a method for restoring contaminated soil.

The present invention is to solve the problem that the secondary damage occurs or the soil is biologically dying to harm the biological adjustment of the soil in the restoration process of the contaminated soil, and to provide a method for restoring contaminated soil nature friendly.

It also aims to address the high cost of facilities and operations due to the need for high energy.

Furthermore, the present invention aims to provide a method for restoring a contaminated soil that maximizes its efficiency in biological treatment and shortens the long-term pollution restoration treatment time.

In order to solve the above problems, the present invention, by activating the microorganisms having the ability to decompose pollutants, carbon (C: Carbon), nitrogen (N: nitrogen), phosphorus (P: phosphorus) and the inorganic porous body on which the microorganisms are supported The method is a method for restoring contaminated soil, characterized in that biologically decomposing contaminants of contaminated soil by mixing the inorganic porous body and the contaminated soil supported by the microorganism.

Preferably, the first step of activating the microorganisms having the ability to decompose pollutants to prepare carbon (C: Carbon), nitrogen (N: nitrogen), phosphorus (P: phosphorus) and the inorganic porous body on which the microorganisms are carried; Digging the contaminated soil, and mixing the excavated contaminated soil and the inorganic porous body on which the microorganisms are loaded at a predetermined ratio; And a third step of periodically supplying air and moisture to the contaminated soil in which the inorganic porous body on which the microorganisms are loaded is mixed.

In the second step, the contaminated soil and the inorganic porous body on which the microorganisms are loaded are stored in respective containers (Hopper) for drawing out separate amounts, and the inorganic porous body on which the contaminated soil and the microorganisms are loaded through the container. Are each withdrawn at a predetermined ratio so that the contaminated soil and the inorganic porous body on which the microorganisms are loaded may be mixed.

Furthermore, the third step may further supply the liquid microbial preparation or nutritional components necessary for the survival of the microorganism through the sparging device.

Preferably, in the second step, the air and water injecting apparatus is installed in the place where the contaminated soil is excavated, and the soil contaminated with the inorganic porous body in which the microorganisms are loaded is refilled in the place where the contaminated soil is excavated. The method may further include installing a top cover to prevent infiltration of foreign substances such as temperature control and excessive moisture from the outside.

Preferably, in the second step, the excavated contaminated soil and the inorganic porous body in which the microorganisms are loaded are mixed at a predetermined ratio and loaded at a predetermined ratio, and loaded in a range of 1 to 5 m. The method may further include periodically stirring the soil.

Preferably, in the second step, the excavated contaminated soil and the inorganic porous body in which the microorganisms are loaded are loaded at a predetermined ratio in a separate place where water and an air injector are installed, and loaded at a rate of 1 to 5 m. The step may further include supplying moisture and air to soil loaded periodically through the moisture and air injector.

Here, in the first step, the mixing moisture content of the organic material and the inorganic porous body is 20 to 75 wt%, and the supported microorganism concentration is 10 ⁵ to 10 ¹² cfu / g.

In addition, the inorganic porous body preferably has a pH of 6 ~ 10.5.

According to the present invention, it is possible to solve the problem that the secondary damage that damages the biological adjustment of the soil or the soil is biologically dead, it is possible to provide a method for restoring the soil contaminated nature.

In addition, in order to solve the problem of the long time required to restore the contaminated soil in the case of using the existing biological method, the period for restoring the contaminated soil is reduced by using the inorganic porous body loaded with microorganisms.

Hereinafter, a method for restoring contaminated soil using an inorganic porous body loaded with microorganisms according to the present invention will be described in detail with reference to a preferred embodiment.

In the present invention, after culturing the microorganisms supported on the inorganic porous body to a certain concentration or more, and restores the biologically contaminated soil by mixing the inorganic porous body and the soil contaminated with microorganisms, Fig. 1 is an inorganic porous body loaded with microorganisms according to the present invention Represents a schematic diagram of a system for restoring contaminated soil using.

The system for restoring contaminated soil using the inorganic porous body loaded with microorganisms includes a container 200a, carbon (C: Carbon), and nitrogen (N) for quantitatively extracting contaminated soil 100 to be restored as shown in FIG. 1. : nitrogen), vessel 200b for quantitatively extracting the inorganic porous body 500 loaded with phosphorus (P: phosphorus) and microorganisms, spraying device 400 for supplying nutrients for microorganisms, water, and contamination And a mixer 300 for evenly mixing the soil and the porous body.

Furthermore, the spreading device 400 may supply the liquid microbial agent to the contaminated soil in which the porous body is mixed.

In addition, by mixing the porous body 500 and the contaminated soil 100 in which the microorganisms are loaded in the mixer 300, the contaminated soil is embedded in a place where the contaminated soil is excavated again to restore the contaminated soil or the mixer 300 in a separate place. The microorganisms are loaded with the porous body 500 and the contaminated soil 100, and then loaded, and periodically supply air and moisture to the loaded contaminated soil, or periodically contaminate through a machine such as a tiller. Soil can be restored.

At this time, in order to prevent the infiltration of foreign matter such as temperature control and excessive moisture, a cover may be installed on top of the embedded soil or loaded soil.

Figure 2 shows a schematic flow diagram of a method for restoring contaminated soil using a porous microorganism-supported inorganic porous body according to the present invention.

As shown in FIG. 2, first, an inorganic porous body is manufactured by using a siliceous raw material and a lime raw material (S110), and the inorganic porous body is loaded with nutrients (S120), and then the decomposition ability of the contaminants in the inorganic porous body is measured. Carry the microorganism with (S130).

In addition, the soil to be restored in the contaminated area is excavated (S140), and the inorganic porous body on which the microorganisms are supported and the contaminated soil excavated are mixed at a predetermined ratio (S150).

Here, in the first step, the mixed moisture content of the nutritional substance and the inorganic porous body is 20 to 75 wt%, and the concentration of the microorganism to be supported is 10 ⁵ to 10 ¹² cfu / g. Also, the inorganic porous body is made to have a pH of 6 to 10.5 as much as possible.

At this time, as described above, the microorganism-supported inorganic porous body and the excavated contaminated soil are stored in a separate container (Hopper) (200a, 200b), and the contaminated soil and the through the container (200a, 200b) The inorganic porous body on which microorganisms are supported may be taken out and mixed at a predetermined ratio.

Here, the contaminated soil mixed with the porous body may be buried again in an excavated place or loaded in a separate place at 1 to 5 m, in order to maintain the temperature of the loaded contaminated soil and prevent penetration of other impurities or rainwater. A cover may be installed on top of the loaded soil.

Thereafter, air and moisture are periodically supplied to the contaminated soil in which the porous body is mixed to help microorganisms decompose contaminants. For this purpose, a device for supplying air and moisture to the place where the contaminated soil is to be loaded in advance can be installed. In addition, liquid microbial agents may be additionally supplied through the device to speed up soil remediation.

Furthermore, the polluted soil mixed with the porous body may be agitated periodically so that the nutrient, moisture and air can be spread evenly.

In the present invention to prepare a microorganism-supported inorganic porous body and to mix it with contaminated soil to restore the contaminated soil, it will be briefly described for the production of the inorganic porous body loaded with microorganisms.

As an embodiment for preparing the inorganic porous body, the inorganic porous body may be prepared by hydrothermal reaction using a foaming agent and an air bubble stabilizer in a siliceous raw material and a lime raw material, which are various as described in one embodiment. An inorganic porous body may be produced by the method.

The inorganic porous body prepared in this way is mixed with a high concentration of organic material, and is fermented to prepare an inorganic porous body supporting nutrients.

Table 1 below shows the amount of nutrients loaded in the porous body that can be used in the present invention.

Target organics Nutritional Amount (wt%) C / N ratio pH Organic matter T-N T-P Axis Part 1 31.8 1.7 1.11 18.7 8.1 Shaft fraction 2 30.4 1.4 0.79 21.7 8.0 Shaft fraction 3 29.2 1.3 0.85 22.5 8.2 Sewage 28.5 1.8 0.61 15.8 8.7 Food waste 32.6 1.1 0.58 29.6 7.8

Organic nutrients may be used in various ways, the organic material of Table 1 is disclosed as an embodiment in the present invention, but is not limited thereto.

In Table 1, the total nitrogen content (TN), the total phosphorus content (TP) and the ratio of carbon to nitrogen (C / N) and the respective pH values were calculated as the mass percentage of each target organic material. It is used as a substance to produce a porous body loaded with nutrients.

When a porous body on which such a nutrient is loaded is prepared, the microorganism is supported on the porous body, and the microorganism is cultured in the porous body.

Through such a process, an inorganic porous body in which microorganisms are supported is manufactured.

Then we look at the contaminated soil restoration effect through various examples of the contaminated soil restoration method using the inorganic porous body loaded with microorganisms according to the present invention.

<Examples>

Table 2 below shows the conditions for experimenting with the same initial oil concentration of the examples according to the present invention and the examples of injecting liquid microorganisms as a general prior art.

Sample Name Initial oil concentration After initial porous mixture
Microbial concentration in soil nutrient
C: N: P
Porous body mixing Liquid microbial injection Example 1 22,000 ppm 5wt%
(1.7x10 ⁶ cfu / goil) - 100: 10: 1 Example 2 22,000 ppm 10wt%
(3.2x10 ⁶ cfu / goil) - 100: 10: 1 Example 3 22,000 ppm 15 wt%
(4.4x10 ⁶ cfu / goil) - 100: 10: 1 Comparative example 22,000 ppm - 10 ⁶ cfu / goil 100: 10: 1

As shown in Table 2, the initial oil concentration is 22,000 ppm and the nutritional component C: N: P is 100: 10: 1, and the soil restoration method according to the present invention and the soil restoration method according to the prior art are performed under the same conditions. .

In the present invention, the microorganisms are loaded on the inorganic porous material and mixed with the contaminated soil. In Example 1 according to the present invention, the concentration of microorganisms per contaminated soil is 1.7x10 ⁶ cfu / g · soil and the microorganisms on the contaminated soil are supported. The mass percentage of the porous body was formed at 5 wt%. In addition, the second embodiment and the third, are each the concentration of microorganisms per contaminated soil 3.2x10 ⁶ cfu / g · soil and 4.4x10 ⁶ cfu / g · soil, the mass percentage of the inorganic porous body microorganisms supported on the contaminated soils are each 10 wt% and 15 wt% were formed.

On the contrary, in the case of the comparative example according to the prior art, the initial oil concentration, which is substantially the same condition as the example according to the present invention, was formed at a condition of 22,000 ppm and the nutrient component C: N: P degree of 100: 10: 1, In addition, experiments were conducted by forming conditions at 10 ⁶ cfu / g · soil, which are almost similar in concentrations of microorganisms per contaminated soil.

By forming the conditions according to Table 2, and experiments for Examples 1, 2, 3 and Comparative Examples according to the prior art according to the present invention, the population for the microorganisms in the soil for each period as shown in Table 3 was confirmed.

Sample Name 1 week 2 weeks 3 weeks 15 Weeks Remarks Example 1 1.1 x ^{10 10} 4.3 x ^{10 9} 5.0 x ^{10 9} 5.4 x ^{10 9} Unit: cfu / goil Example 2 1.8 x ^{10 10} 5.6 x ^{10 9} 5.7 x ^{10 9} 6.7 x ^{10 9} Example 3 2.5 x ^{10 10} 5.1 x ^{10 9} 1.7 x ^{10 9} 4.2 x ^{10 9} Comparative example 1.7 x ^{10 8} 1.9 x ^{10 8} 2.6 x 10 ⁷ 2.0 x 10 ⁶

According to the experimental results shown in Table 3 above, it can be seen that the total number of microorganisms in the contaminated soil is significantly increased in the case of the embodiment according to the present invention as a whole.

In the case of the comparative example according to the prior art, since the increase in the number of microorganisms is slow, the time taken for restoring the contaminated soil becomes long, so the efficiency is lowered.

However, in the case of the embodiment according to the present invention, it can be seen that the population of microorganisms is rapidly increased by supporting the microorganisms in the inorganic porous body and mixed with the contaminated soil, so that the contaminated soil can be restored within a faster period than the conventional art. The efficiency is increased.

This effect is caused by mixing the inorganic porous body loaded with microorganisms with the contaminated soil, as in the present invention, and the inorganic porous body has better water retention than ordinary soils, so it absorbs more water and also has less amount of outflowed water. do. The moisture retention capacity of the inorganic porous body can keep a large amount of water necessary for long-term microbial activity for a long time, and since the porous body absorbs moisture generated when microorganisms decompose contaminants such as oil, the effect of suppressing leachate is generated. .

In addition, the inorganic porous body according to the present invention has sufficient nutrients such as C, N, P necessary for microbial metabolism, and the contaminated soil in which the porous body is mixed due to the porous body increases porosity, thereby smoothly supplying oxygen.

Due to the characteristics of the inorganic porous body, as shown in the above experimental examples, the number of microorganisms decomposing contaminants rapidly increases over time, thereby maximizing the restoration efficiency of the contaminated soil.

3 is a graph showing the contaminated soil restoration effect for Examples 1, 2, 3 and Comparative Examples according to the prior art according to the present invention.

The y-axis of FIG. 3 represents the total petroleum hydrocarbon (THP) on a log scale, and the x-axis represents the course of days.

As shown in the graph of FIG. 3, in the case of the comparative example of the prior art, the slope for restoring the contaminated soil is -0.0034 (K = -0.0034), so that the THP of the contaminated soil is lowered little by little over a long time. Although it takes a long time, when using the inorganic porous body loaded with the microorganism according to the present invention, since the slope is steeper than the prior art as a whole, it is possible to restore the contaminated soil in a much faster time, thereby increasing its efficiency.

Looking at the results for each embodiment in more detail, in the case of Example 1 according to the present invention, the slope according to the TPH decrease for each period is -0.0051 (K = -0.0051), in the case of Example 2- At 0.0059 (K = -0.0059), the slope was -0.0065 (K = -0.0065) for Example 3.

Therefore, the restoration method of the contaminated soil using the microorganism-supported inorganic porous body according to the present invention can restore the contaminated soil in a much faster time than the conventional method of restoring contaminated soil according to the prior art, and thus, the efficiency of restoring contaminated soil It can be seen that this is high.

4 and 5 are graphs showing the results of experiments on the characteristics of the soil after mixing the inorganic porous body in the soil.

Here, the clay was used as clay soil, and the experiment was carried out using a sample formed by passing a sieve of 2.36 mm and having a water content of 2 wt% or less.

4 is a graph of the air permeability of the soil, the y-axis represents the air permeability, the x-axis represents the thickness of the loaded soil, the air permeability P was calculated as (V * h) / (P * A * t). Where P is the air permeability (ml / cm 2 · min), V is the air volume (ml), h is the thickness (cm), P is the pressure (cmH ₂ O), A is the cross-sectional area (cm ² ), and t is the time (min). Indicates.

As shown in the graph of Figure 4 it can be seen that the excellent air permeability when the particle size of the inorganic porous body than the case of only 100% soil.

5 is a graph for improving the water holding capacity in the soil, where the y-axis shows the permeation rate and the x-axis shows the amount of the inorganic porous body.

As shown in the graph of FIG. 5, in the case of the soil without mixing the inorganic porous body, the permeation rate is much faster than that of the soil mixed with the inorganic porous body, and the permeation rate is lowered as the amount of the inorganic porous body is increased. You can check it.

This is because the inorganic porous body has better water retention than the general soil, so the soil mixed with the porous body may contain much more water than when only the soil exists.

In addition, if water is continuously supplied to the inorganic porous body when the water is continuously absorbed, excess water flows out, so that the permeation rate decreases as the mixing ratio of the inorganic porous body to the soil increases.

From the graphs of the soil characteristics shown in Figs. 4 and 5, it can be seen that the soil mixed with the inorganic porous body has better air permeability and a lower permeation rate than the soil without the soil. When nutrients, moisture and air are supplied to the soil, the soil mixed with the inorganic porous body can supply the nutrients evenly to the microorganisms spread throughout and increase the water content of the soil, thereby obtaining much more effective results.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Accordingly, the embodiments described in the present invention are not intended to limit the technical spirit of the present invention but to describe the technical spirit of the present invention. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a schematic configuration diagram of a system for restoring contaminated soil using a microorganism-supported inorganic porous body according to the present invention.

Figure 2 shows a schematic flow diagram of a method for restoring contaminated soil using a porous microorganism-supported inorganic porous body according to the present invention.

3 is a graph showing the contaminated soil restoration effect for Examples 1, 2, 3 and Comparative Examples according to the prior art according to the present invention.

4 and 5 are graphs showing the results of experiments on the characteristics of the soil after mixing the porous body in the soil according to the present invention.

<Description of the symbols for the main parts of the drawings>

100: contaminated soil, 200a, 200b: Hopper, 300: mixer,

400: spraying apparatus, 500: inorganic porous body loaded with microorganisms.

Claims (9)

A first step of preparing an inorganic porous body using a siliceous raw material and a lime raw material; A second method of preparing an inorganic porous body in which nutritional ingredients are supported by mixing organic materials including carbon (C: Carbon), nitrogen (N: nitrogen), and phosphorus (P: phosphorus) to fermentation process step; A third step of preparing an inorganic porous body in which the microorganisms are supported by culturing the microorganisms in the inorganic porous body and culturing the microorganisms; Digging the contaminated soil, and mixing the excavated contaminated soil with the inorganic porous body on which the nutrients and microorganisms are loaded at a predetermined ratio; And And a fifth step of periodically supplying air and moisture to the contaminated soil mixed with the nutrient and the microorganism loaded thereon. delete The method of claim 1, The fourth step, The contaminated soil and the inorganic porous body carrying the nutrients and microorganisms are stored in each container (Hopper) to take out in a separate quantity, and the contaminated soil and the inorganic porous bodies carrying the nutrients and microorganisms are stored through the container. A method of restoring contaminated soil, characterized in that the contaminated soil and the inorganic porous body carrying the nutrients and microorganisms are mixed at a predetermined ratio. The method of claim 1, The fifth step, Soil recovery method characterized in that the liquid microbial agent is further supplied through the spreading device. The method of claim 1, The fourth step, Install an air and moisture injector at the place where the contaminated soil is excavated, refill the contaminated soil in which the mineral porous material loaded with the nutrient and microorganisms are mixed at the place where the contaminated soil is excavated, and control the temperature from the outside. Polluted soil restoration method further comprising the step of installing a top cover to prevent the penetration of foreign matters. The method of claim 1, The fourth step, In a separate place, the excavated contaminated soil and the inorganic porous body in which the nutrients and microorganisms are loaded are mixed at a predetermined ratio and loaded at 1 to 5 m, The fifth step, Periodically stirring the loaded contaminated soil, wherein air is supplied to the loaded contaminated soil through the stirring process. The method of claim 1, The fourth step, In a separate place where water and air injectors are installed, the excavated contaminated soil and the inorganic porous body loaded with the nutrients and microorganisms are mixed at a predetermined ratio and loaded at 1 to 5 m, The fifth step, Polluted soil restoration method further comprising the step of supplying water and air to the soil periodically loaded through the water and air injection device. The method of claim 1, The inorganic porous body is prepared by mixing the organic material and the inorganic porous body in the second and third stages with a water content of 20 to 75 wt% and carrying the supported microorganism concentration of 10 ⁵ to 10 ¹² cfu / g. Soil restoration method. The method according to any one of claims 1 and 3 to 7, The inorganic porous body is a contaminated soil restoration method characterized in that it has a pH of 6 ~ 10.5.

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