JP4586592B2 - Purification system for oil-contaminated soil - Google Patents

Description

The present invention relates to an oil-contaminated soil purification system that mainly purifies contaminated soil by removing oil contained in excavated soil.

  If the soil of the factory site is contaminated with oil, the oil will not diffuse into the environment and interfere with the lives of the residents in the surrounding area. Appropriate purification measures are required.

  The contaminated soil contaminated with oil has been subjected to purification treatment by various methods in the past, and a typical example is heat treatment.

  In such a treatment method, oil contained in the contaminated soil is removed by heating the oil-contaminated soil.

  As a means for heating, a rotary heating furnace called a rotary kiln is known. If oil-contaminated soil is heated using such a heating furnace, oil can be efficiently removed.

JP 2003-266058 A

  Here, since contaminated soil usually diffuses into the ground in a radial pattern with the contamination source as the center, not only the contamination source but also a corresponding range of soil spreading around it must be excavated, and the excavated soil must be heated in a rotary furnace. I must.

  For this reason, the rotary furnace must also have a scale capable of treating a large amount of contaminated soil, which causes a problem that enormous costs are required for the oil removal treatment.

  Moreover, the area contaminated with light oil and the area contaminated with heavy oil may be mixed in the contaminated soil, and in this case, the same problem as described above occurs.

The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an oil-contaminated soil purification system capable of efficiently performing purification processing of oil-contaminated soil areas distributed over a wide range. .

In order to achieve the above-mentioned object, the oil-contaminated soil purification system according to the present invention heats highly-contaminated soil excavated from the highly-contaminated soil region among the contaminated soil regions containing oil as described in claim 1. A heating furnace that removes the oil component by processing, and a microbial decomposition treatment means that removes the oil component by microbially decomposing the low-concentration contaminated soil excavated from the low-concentration contaminated region spreading around the high-concentration contaminated region The microbial decomposition treatment means is provided with a ventilation pipe embedded in the low-concentration contaminated soil piled up in a bowl shape as a biopile or airtightly arranged near the surface thereof, and the heating furnace is indirectly heated. The rotary kiln is arranged so as to be able to exchange heat with the exhaust pipe connected to the exhaust port of the indirectly heated rotary kiln. Is the passing connected air inlet tube that connects communication with the vent pipe.

Moreover, the purification system of the oil-contaminated soil which concerns on this invention heat-treats the heavy oil-contaminated soil excavated from the heavy oil-contaminated area among the contaminated soil areas containing an oil component, as described in Claim 2. And a microbial decomposition treatment means for removing the oil by microbially decomposing light oil contaminated soil excavated from the light oil-contaminated area. In addition, the microbe decomposition treatment means includes a ventilation pipe embedded in the light oil-contaminated soil or air-tightly arranged near the surface thereof, and the heating furnace is an indirect heating rotary kiln, and an exhaust port of the indirect heating rotary kiln An air introduction pipe that is arranged to be able to exchange heat with an exhaust gas pipe that is connected to the exhaust pipe and that is connected to an outer cylinder of the indirectly heated rotary kiln is connected to the vent pipe. It is intended.

In addition, the oil-contaminated soil purification system according to the present invention is, as described in claim 3 , by heat-treating high-concentration contaminated soil excavated from the high-concentration contaminated region among the contaminated soil regions containing oil. A heating furnace for removing oil, and microbial decomposition treatment means for removing the oil by microbially decomposing low-concentration contaminated soil excavated from the low-concentration contaminated area spreading around the high-concentration contaminated area, The microbe decomposition treatment means includes a ventilation pipe embedded in the low-concentration contaminated soil piled up as a pile or airtightly arranged near the surface thereof, and the heating furnace is a direct heating rotary kiln, The exhaust pipe connected to the heated air discharge port of the direct heating rotary kiln is arranged so as to be able to exchange heat and communicates with the inner space of the cylinder of the direct heating rotary kiln. Is connected air inlet tube that connects communication with the vent pipe.

Moreover, the purification system of the oil-contaminated soil which concerns on this invention heat-treats the heavy oil-contaminated soil excavated from the heavy oil-contaminated area among the contaminated soil areas containing an oil component, as described in Claim 4. And a microbial decomposition treatment means for removing the oil by microbial decomposition treatment of the light oil contaminated soil excavated from the light oil contaminated area, and is accumulated in a bowl shape as a biopile. In addition, the microbe decomposition treatment means includes a ventilation pipe embedded in the light oil-contaminated soil or arranged in the vicinity of the surface thereof, and the heating furnace is a direct heating rotary kiln, and the heating air of the direct heating rotary kiln An air introduction pipe which is arranged so as to be able to exchange heat with an exhaust gas pipe connected to an exhaust port and connected to an inner space of a cylinder of the direct heating type rotary kiln is connected to the passage. It is obtained by communicatively connected to the tube.

  The applicant has roughly classified oil-contaminated soil into high-concentration contaminated areas called hot spots and low-concentration contaminated areas spreading around the area, and the amount of soil to be treated is overwhelming in the low-concentrated contaminated areas. As a result of conducting various researches, the high-concentration contaminated soil excavated from the high-concentration contaminated area is heat-treated, and the low-concentrated contaminated soil excavated from the low-concentrated contaminated area is subjected to microbial decomposition treatment. In this way, we have obtained very useful knowledge in the industry that a large amount of oil-contaminated soil can be treated efficiently.

That is, in the method for purifying oil-contaminated soil according to the first reference invention , first, the contaminated soil area containing oil is divided into a high-concentration contaminated area and a low-concentrated contaminated area extending around it. The oil content is removed by heat-treating the excavated high-concentration contaminated soil, and the oil content is removed by microbial decomposition treatment of the low-concentration contaminated soil excavated from the low-concentration contaminated area.

  In this way, low-concentration contaminated soil that has a low oil concentration but is generated in large quantities can be removed by a relatively inexpensive treatment method called microbial decomposition, and the soil concentration is small but the contamination concentration is high. Oil content can be reliably removed from the contaminated soil by a treatment method called heat treatment.

  Therefore, it is possible to efficiently purify the pollution source and the oil-contaminated soil that has spread around it.

  In addition, the Applicant is aware that areas contaminated with heavy oil and areas contaminated with light oil are mixed in oil-contaminated soil, and that the amount of light oil-contaminated soil is not limited, As a result of the research, if the heavy oil contaminated soil excavated from the heavy oil contaminated area is heat treated and the light oil contaminated soil excavated from the light oil contaminated area is subjected to microbial decomposition treatment, a large amount of oil contaminated soil will be obtained. It has been the result of obtaining very useful knowledge in the industry that can be processed efficiently.

That is, in the method for purifying oil-contaminated soil according to the second reference invention , first, the contaminated soil area containing oil was divided into a heavy oil-contaminated area and a light oil-contaminated area, and excavated from the heavy oil-contaminated area. The oil is removed by heat-treating the heavy oil-contaminated soil, and the light oil-contaminated soil excavated from the light oil-contaminated area is microbially decomposed to remove the oil.

  In this way, light oil-contaminated soil that is easy to treat because of light oil but can be removed in large quantities can be removed by a relatively inexpensive treatment method called microbial decomposition treatment, and heavy oil that is difficult to decompose with microorganisms can be removed. Oil content can be reliably removed from the quality oil contaminated soil by a treatment method called heat treatment.

  Therefore, it becomes possible to efficiently purify oil-contaminated soil in which heavy oil-contaminated areas and light oil-contaminated areas are mixed.

In the first reference invention and the second reference invention, if the microbial decomposition treatment is performed using the heated air generated by the heat treatment, the waste heat of the heat treatment can be effectively used in the microbial decomposition treatment. This makes it possible to further reduce the purification cost.

In the system for purifying oil-contaminated soil according to the third reference invention , the contaminated soil area containing oil is divided into a high-concentration contaminated area and a low-concentrated contaminated area extending around the high-concentrated contaminated area. Oil concentration is removed by heat-treating the concentration-contaminated soil in a heating furnace, and oil concentration is removed by microbially decomposing the low-concentration contaminated soil excavated from the low-concentration contaminated area using a microbial decomposition treatment means.

  In this way, it is possible to remove low-concentration contaminated soil that has a low oil concentration but a large amount by a relatively inexpensive treatment called microbial decomposition treatment, and a high concentration with a small amount of soil but high contamination concentration. Oil can be reliably removed from the contaminated soil by heat treatment using a heating furnace.

  Therefore, it is possible to efficiently purify the pollution source and the oil-contaminated soil that has spread around it.

In the purification system for oil-contaminated soil according to the fourth reference invention , the contaminated soil area containing oil is divided into a heavy oil-contaminated area and a light oil-contaminated area, and heavy oil contamination excavated from the heavy oil-contaminated area Oil is removed by heat-treating the soil in a heating furnace, and light oil-contaminated soil excavated from the light oil-contaminated area is subjected to microbial decomposition treatment by a microbial decomposition treatment means.

  In this way, light oil-contaminated soil that is easy to treat because of light oil but can be removed in large quantities can be removed by a relatively inexpensive treatment method called microbial decomposition treatment, and heavy oil that is difficult to decompose with microorganisms can be removed. Oil content can be reliably removed from the quality oil contaminated soil by a treatment method called heat treatment.

  Therefore, it becomes possible to efficiently purify oil-contaminated soil in which heavy oil-contaminated areas and light oil-contaminated areas are mixed.

In configuring the microbial decomposition treatment means, it may be configured to be able to supply moisture and air so as to increase the decomposition activity by microorganisms and to be able to maintain the temperature appropriately, in the present invention, The microbial decomposition treatment means includes a ventilation pipe embedded in the low-concentration contaminated soil or light oil-contaminated soil piled up as a biopile or airtightly disposed near the surface thereof, and the heating furnace Is an indirect heating rotary kiln, and an air introduction pipe connected to the outer cylinder of the indirect heating rotary kiln is connected to the exhaust pipe connected to the exhaust port of the indirect heating rotary kiln and connected to the outer cylinder of the indirect heating rotary kiln. since communicatively connected, the waste heat of the heat treatment it is possible to effectively use in microbial degradation process, further lowering the purification costs It becomes possible.

Similarly, the microbial decomposition treatment means includes a ventilation pipe embedded in the low-concentration contaminated soil or the light oil-contaminated soil piled up as a biopile or airtightly arranged near the surface of the soil. The heating furnace is a direct heating rotary kiln, and the air introduction is arranged so as to be able to exchange heat with the exhaust gas pipe connected to the heated air discharge port of the direct heating rotary kiln, and connected to the cylindrical internal space of the direct heating rotary kiln. since the tube is connected in communication with the vent tube, the waste heat of the heat treatment it is possible to effectively use in microbial degradation process, it is possible to further reduce the cleaning cost.

Embodiments of a purification system for oil-contaminated soil according to the present invention will be described below with reference to the accompanying drawings. Note that components that are substantially the same as those of the prior art are assigned the same reference numerals, and descriptions thereof are omitted.

(First embodiment)

  FIG. 1 is a schematic diagram illustrating a purification system for oil-contaminated soil according to the present embodiment. As can be seen from the figure, the oil-contaminated soil purification system 1 according to the present embodiment is generally composed of an indirectly heated rotary kiln 2 as a heating furnace and a bioremediation system 3 as a microbial decomposition treatment means.

  As shown in FIG. 2, the indirectly heated rotary kiln 2 heats high-concentration contaminated soil having a high oil concentration excavated from a high-concentration contaminated region 21, which is also called a hot spot, in the contaminated soil region 23 containing oil. It is like that.

  As shown in FIG. 1, the indirectly heated rotary kiln 2 includes an inner cylinder 4 in which high-concentration contaminated soil is held in an internal space, and an outer cylinder 5 in which the inner cylinder is accommodated in the form of a double cylinder. A burner 6 is attached to one end of the cylinder, and the air introduced through the air introduction pipe 7 connected to the outer cylinder 5 and receiving waste heat from the heat exchanger 8 is heated by the burner 6 to be heated air. By introducing this into the outer cylinder 5, the inner cylinder 4 as a hook can be heated from the surroundings.

  The inner cylinder 4 is configured such that an intermediate portion except for both end portions is rotatable around a cylinder axis, and an inlet 9 and an exhaust port 11 for introducing high-concentration contaminated soil into one end are provided. An air supply port 10 and a treated soil discharge port 13 are provided at the other end, respectively, and the high-concentration contaminated soil in the inner cylinder is heated by the heated air flowing outside the inner cylinder 4, and The oil component is volatilized or oxidatively decomposed, and the exhaust gas can be discharged from the exhaust port by being entrained in the flow of air passing from the supply port 10 to the exhaust port 11. Incidentally, the treated soil from which oil has been removed is discharged from the treated soil discharge port 13 as treated soil.

  The air supply port 10 of the inner cylinder 4 is connected to a heated air discharge port 12 provided at the end of the outer cylinder 5 on the opposite side to the burner 6, and the heated air is connected to the inner cylinder 4. To be introduced. That is, the air heated by the burner 6 flows into the outer cylinder 5 and is used to heat the inner cylinder 4, and is then introduced into the inner cylinder from the air supply port 10 of the inner cylinder 4, Is reused to volatilize or oxidatively decompose.

  On the other hand, the bioremediation system 3 includes a biopile 15 in which low-concentration soil having a low oil concentration excavated from a low-concentration contamination region 22 spreading around the high-concentration contamination region 21 is accumulated on the ground surface in a bowl shape, It is generally composed of a ventilation pipe 16 embedded in the pile, and if necessary, a watering device or a nutrient salt addition device (not shown) may be appropriately provided.

  The vent pipe 16 is composed of a main pipe and a plurality of perforated pipes branched and connected to the main pipe via a header, and each of the perforated pipes is embedded in each biopile 15 described above.

  Here, the upstream side of the ventilation pipe 16 is connected to the air introduction pipe 7 so that the warm air that has received waste heat from the heat exchanger 8 can be sent to the biopile 15 through the ventilation pipe 16. Even if the outside air temperature is low by supplying hot air introduced from the vent pipe 16, for example, air of 40 ° C. to 60 ° C., into the biopile 15, The soil temperature is appropriately maintained at a temperature of about 30 ° C. where microorganisms are likely to be active.

  And the temperature maintenance by such warm air and nutrient salt and water supply action combine, and the decomposition activity of microorganisms becomes high, and thus the oil in the biopile 15 can be efficiently decomposed by microorganisms.

  The temperature of the air fed into the biopile 15 from the vent pipe 16 is, for example, 40 ° C to 60 ° so that the temperature in the soil in the biopile is a temperature suitable for microbial decomposition activity, for example, around 30 ° C. If the temperature of the hot air from the air introduction pipe 7 is too high, the outside air may be mixed into the ventilation pipe 16 as appropriate, and then fed into the biopile 15. .

  As the cells, soil bacteria may be used as they are, or appropriate selected bacteria may be used according to the oil concentration.

  The oil-contaminated soil purification system 1 includes an exhaust gas treatment device 19 composed of a secondary combustion furnace, and oxidatively decomposes and treats oil remaining in the exhaust gas discharged through the exhaust port 11 of the indirectly heated rotary kiln 2. The exhausted gas is discharged to the atmosphere through the exhaust gas pipe 33 and the waste heat is transmitted to the air in the air introduction pipe 7 by the heat exchanger 8.

  In order to purify oil-contaminated soil using the oil-contaminated soil purification system 1 according to the present embodiment, first, the inner cylinder 4 of the indirectly heated rotary kiln 2 is made high via the inlet 9 of the indirectly heated rotary kiln 2. Concentrate contaminated soil.

  Next, the air introduced through the heat exchanger 8 and the air introduction pipe 7 is heated by the burner 6 to form heated air, and this is introduced into the outer cylinder 5, thereby surrounding the inner cylinder 4 as a pot. The heated air used for heating the inner cylinder 4 is introduced into the inner cylinder from the air supply port 10 of the inner cylinder 4.

  In this way, the oil contained in the high-concentration contaminated soil in the inner cylinder 4 is volatilized or oxidatively decomposed, and the exhaust gas is entrained in the flow of air passing from the air supply port 10 to the exhaust port 11. Exhaust from the exhaust port.

  The heating temperature is, for example, about 200 to 300 ° C., and is suitably adjusted depending on the oil concentration.

  On the other hand, the low-concentration soil excavated from the low-concentration contamination area 22 spreading around the high-concentration contamination area 21 is piled up on the ground surface to form a biopile 15 and a ventilation pipe 16 is embedded in the biopile. The upstream side of the ventilation pipe is connected to the air introduction pipe 7 in communication.

  And the warm air which received the waste heat from the heat exchanger 8 in this state is sent into the biopile 15 through the vent pipe 16, and the microorganism activity is enhanced by maintaining the temperature by the warm air to promote the decomposition rate of the oil. .

  Next, the oil remaining in the exhaust gas discharged through the exhaust port 11 of the indirectly heated rotary kiln 2 is subjected to secondary combustion in the exhaust gas treatment device 19 for oxidative decomposition, and then the treated exhaust gas is passed through the exhaust gas pipe 33. To the atmosphere.

  As described above, according to the purification system 1 and the purification method for oil-contaminated soil according to the present embodiment, first, the contaminated soil area 23 containing oil is spread over the high-concentration contaminated area 21 and its surroundings. The high-concentration contaminated soil excavated from the high-concentration contaminated area 21 is heated by the indirect heating rotary kiln 2, and the low-concentration contaminated soil excavated from the low-concentrated contaminated area is microbially decomposed by the bioremediation system 3. As a result, it is possible to remove oil from low-concentration contaminated soil that is generated in large quantities but with a low concentration by using a relatively inexpensive and safe treatment method called microbial decomposition, and the soil concentration is low but the contamination concentration is low. The oil content can be removed from the high-concentration contaminated soil with a high temperature by a treatment method called heat treatment capable of reliable volatilization or oxidative decomposition.

  Therefore, even in a small heating furnace, it becomes possible to efficiently purify a large amount of oil-contaminated soil that spreads around the pollution source and its surroundings, and thus it is possible to construct a highly efficient purification system with excellent economic efficiency. Become.

  In addition, with the above-described configuration, it is possible to reliably purify the oil-contaminated soil so as to satisfy the environmental standards for both the high-concentration contaminated soil and the low-concentration contaminated soil.

  Moreover, according to the purification system 1 and the purification method for oil-contaminated soil according to the present embodiment, the microbial decomposition treatment in the bioremediation system 3 is performed using the heated air generated by the heat treatment of the indirect heating rotary kiln 2. Therefore, even in a cold climate, it is possible to save energy for heating by effectively utilizing the waste heat of the heat treatment in the microbial decomposition treatment, and the purification cost can be further reduced.

In the present embodiment , the combustion type is adopted as the exhaust gas treatment device, but an activated carbon adsorption method may be adopted instead.

  In the present embodiment, the contaminated soil area containing oil is divided into a high-concentration contaminated area and a low-concentrated contaminated area extending around the high-concentration contaminated area. In addition to removing oil by removing microorganisms from the low-contaminated soil excavated from the low-concentration contaminated area, the contaminated soil area containing the oil is treated as a heavy oil-contaminated area. The oil is removed by heating the heavy oil contaminated soil excavated from the heavy oil contaminated area with the indirect heating rotary kiln 2 and the light oil excavated from the light oil contaminated area. The oil content may be removed by subjecting the oil-contaminated soil to a microbial decomposition treatment using the bioremediation system 3.

  According to such a configuration, light oil contaminated soil that is easy to treat because of light oil but is generated in a relatively large amount can be removed by a relatively inexpensive treatment method called microbial decomposition treatment using the bioremediation system 3. In addition, heavy oil-contaminated soil that is difficult to decompose with microorganisms can be reliably removed by a treatment method called heat treatment using the indirectly heated rotary kiln 2.

  Therefore, it becomes possible to efficiently purify oil-contaminated soil in which heavy oil-contaminated areas and light oil-contaminated areas are mixed.

  In such a configuration, the high-concentration contaminated soil is replaced with heavy oil-contaminated soil, and the low-concentration contaminated soil is replaced with light oil-contaminated soil. Although omitted, when the heavy oil-contaminated soil is heat-treated with the indirectly heated rotary kiln 2, the heating temperature is preferably set to about 600 ° C.

  In the present embodiment, the ventilation pipe 16 is embedded in the biopile 15. However, instead of such a configuration, the ventilation pipe 16 may be airtightly disposed near the surface of the biopile 15.

  As a configuration in which the ventilation pipe 16 is disposed in an airtight manner, for example, a configuration in which the biopile 15 is covered with an airtight sheet and the ventilation pipe 16 is disposed between the airtight sheet and the surface of the biopile 15 is conceivable.

  Further, in the present embodiment and the above-described modification, the vent pipe 16 is connected to the air introduction pipe 7 so that the warm air from the air introduction pipe is sent to the biopile 15 through the vent pipe 16. However, instead of such a configuration, the air introduction pipe 7 is connected to the hot water generator and the hot water is taken out from the water pipe connected to the hot water generator, and the water pipe is embedded in the biopile 15. Alternatively, they may be arranged near the surface thereof.

(Second Embodiment)

  Next, a second embodiment will be described. Note that components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 3 is a schematic view showing a purification system for oil-contaminated soil according to the present embodiment. As can be seen from the figure, the oil-contaminated soil purification system 31 according to this embodiment is generally composed of a direct heating rotary kiln 32 as a heating furnace and a bioremediation system 3 as a microbial decomposition treatment means.

  The direct heating rotary kiln 32 heats high-concentration contaminated soil excavated from the high-concentration contaminated region 21 in the contaminated soil region 23 containing oil.

  As shown in FIG. 3, the direct heating rotary kiln 32 includes a cylindrical body in which high-concentration contaminated soil is held in an internal space and an intermediate portion is configured to be rotatable around a cylindrical axis, and a burner 6 is provided at one end of the cylindrical body. The air that has been introduced through the air introduction pipe 7 connected to the cylinder and receives the waste heat from the heat exchanger 8 is heated by the burner 6 to be heated air, and this is introduced into the cylinder. As a result, the highly-contaminated soil in the cylinder can be heat-treated.

  The direct heating rotary kiln 32 is provided with a treated soil discharge port 13a at the end of the same cylinder where the burner 6 is provided, and an input port 9a and an exhaust port for supplying high-concentration contaminated soil to the other end of the cylinder. 11a is provided, and the high-concentration contaminated soil in the cylindrical body is heat-treated by the heated air from the burner 6, and the oil is volatilized or oxidatively decomposed by the heat treatment. The exhaust gas is discharged from the exhaust port 11a. After being discharged, the oil component is oxidatively decomposed by the exhaust gas treatment device 19 composed of a secondary combustion furnace, and then released to the atmosphere via the exhaust gas pipe 33. Incidentally, the treated soil from which oil has been removed is discharged from the treated soil discharge port 13a as treated soil.

  On the other hand, the bioremediation system 3 includes a biopile 15 in which low-concentration soil having a low oil concentration excavated from a low-concentration contamination region 22 spreading around the high-concentration contamination region 21 is accumulated on the ground surface in a bowl shape, It is generally composed of a ventilation pipe 16 embedded in the pile, and if necessary, a watering device or a nutrient salt addition device (not shown) may be appropriately provided.

  The vent pipe 16 is composed of a main pipe and a plurality of perforated pipes branched and connected to the main pipe via a header, and each of the perforated pipes is embedded in each biopile 15 described above.

  Here, the upstream side of the ventilation pipe 16 is connected to the air introduction pipe 7 so that the warm air that has received waste heat from the heat exchanger 8 can be sent to the biopile 15 through the ventilation pipe 16. Even if the outside air temperature is low by supplying hot air introduced from the vent pipe 16, for example, air of 40 ° C. to 60 ° C., into the biopile 15, The soil temperature is appropriately maintained at a temperature of about 30 ° C. where microorganisms are likely to be active.

  And the temperature maintenance by such warm air and nutrient salt and water supply action combine, and the decomposition activity of microorganisms becomes high, and thus the oil in the biopile 15 can be efficiently decomposed by microorganisms.

  The temperature of the air fed into the biopile 15 from the vent pipe 16 is, for example, 40 ° C to 60 ° so that the temperature in the soil in the biopile is a temperature suitable for microbial decomposition activity, for example, around 30 ° C. If the temperature of the hot air from the air introduction pipe 7 is too high, the outside air may be mixed into the ventilation pipe 16 as appropriate, and then fed into the biopile 15. .

  As the cells, soil bacteria may be used as they are, or appropriate selected bacteria may be used according to the oil concentration.

  The oil-contaminated soil purification system 31 includes an exhaust gas treatment device 19 including a secondary combustion furnace, and oxidatively decomposes and treats oil remaining in the exhaust gas discharged through the exhaust port 11a of the direct heating rotary kiln 32. The exhausted gas is discharged to the atmosphere through the exhaust gas pipe 33 and the waste heat is transmitted to the air in the air introduction pipe 7 by the heat exchanger 8.

  In order to purify oil-contaminated soil using the oil-contaminated soil purification system 31 according to the present embodiment, first, a high concentration is applied to the cylinder of the direct heating rotary kiln through the inlet 9a of the direct heating rotary kiln 32. Put contaminated soil.

  Next, the air introduced through the heat exchanger 8 and the air introduction pipe 7 is heated by the burner 6 to form heated air, and this is introduced into the cylinder to volatilize the oil from the highly-contaminated soil in the cylinder. Alternatively, the exhaust gas is exhausted from the exhaust port 11a while being oxidatively decomposed.

  The heating temperature is preferably about 200 ° C. to 300 ° C., for example, and may be appropriately adjusted depending on the oil concentration.

  On the other hand, the low-concentration soil excavated from the low-concentration contamination area 22 spreading around the high-concentration contamination area 21 is piled up on the ground surface to form a biopile 15 and a ventilation pipe 16 is embedded in the biopile. The upstream side of the ventilation pipe is connected to the air introduction pipe 7 in communication.

  In such a state, warm air that has received waste heat generated in the direct heating rotary kiln 32 is sent into the biopile 15 through the vent pipe 16, and the microorganism activity is increased by maintaining the temperature by the warm air, thereby decomposing the oil. To promote.

  Next, the oil remaining in the exhaust gas discharged from the exhaust port 11a of the direct heating rotary kiln 32 is subjected to secondary combustion in the exhaust gas treatment device 19 for oxidative decomposition, and then the treated exhaust gas is passed through the exhaust gas pipe 33 to the atmosphere. To release.

  As described above, according to the purification system 31 and the purification method for oil-contaminated soil according to the present embodiment, first, the contaminated soil area 23 containing the oil component is spread over the high-concentration contaminated area 21 and its surroundings. The high-concentration contaminated soil excavated from the high-concentration contaminated area 21 is directly heated by the rotary kiln 32, and the low-concentration contaminated soil excavated from the low-concentrated contaminated area is microbially decomposed by the bioremediation system 3. As a result, it is possible to remove oil from low-concentration contaminated soil that is generated in large quantities but with a low concentration by using a relatively inexpensive and safe treatment method called microbial decomposition, and the soil concentration is low but the contamination concentration is low. The oil content can be removed from the high-concentration contaminated soil with a high temperature by a treatment method called heat treatment capable of reliable volatilization or oxidative decomposition.

  Therefore, even in a small heating furnace, it becomes possible to efficiently purify a large amount of oil-contaminated soil that spreads around the pollution source and its surroundings, and thus it is possible to construct a highly efficient purification system with excellent economic efficiency. Become.

  In addition, with the above-described configuration, it is possible to reliably purify the oil-contaminated soil so as to satisfy the environmental standards for both the high-concentration contaminated soil and the low-concentration contaminated soil.

  Further, according to the purification system 31 and the purification method for oil-contaminated soil according to the present embodiment, the microbial decomposition treatment in the bioremediation system 3 is performed using the heat of the exhaust gas generated by the heat treatment of the direct heating rotary kiln 32. Therefore, even in a cold climate, it is possible to save energy for heating by effectively utilizing the waste heat of the heat treatment in the microbial decomposition treatment, and the purification cost can be further reduced.

In the present embodiment , the combustion type is adopted as the exhaust gas treatment device, but an activated carbon adsorption method may be adopted instead.

  In the present embodiment, the contaminated soil area containing oil is divided into a high-concentration contaminated area and a low-concentrated contaminated area extending around the high-concentration contaminated area. In addition to removing oil by removing microorganisms from the low-contaminated soil excavated from the low-concentration contaminated area, the contaminated soil area containing the oil is treated as a heavy oil-contaminated area. The oil is removed by heating the heavy oil-contaminated soil excavated from the heavy oil-contaminated area directly with the rotary kiln 32 and the light oil excavated from the light oil-contaminated area. The oil content may be removed by subjecting the oil-contaminated soil to a microbial decomposition treatment using the bioremediation system 3.

  According to such a configuration, light oil contaminated soil that is easy to treat because of light oil but is generated in a relatively large amount can be removed by a relatively inexpensive treatment method called microbial decomposition treatment using the bioremediation system 3. In addition, heavy oil-contaminated soil that is difficult to decompose with microorganisms can be reliably removed by a treatment method called heat treatment using the direct heating rotary kiln 32.

  Therefore, it becomes possible to efficiently purify oil-contaminated soil in which heavy oil-contaminated areas and light oil-contaminated areas are mixed.

  In such a configuration, the high-concentration contaminated soil is replaced with heavy oil-contaminated soil, and the low-concentration contaminated soil is replaced with light oil-contaminated soil. Although omitted, when the heavy oil-contaminated soil is heat-treated directly by the rotary kiln 32, the heating temperature is preferably set to about 600 ° C.

  In the present embodiment, the ventilation pipe 16 is embedded in the biopile 15. However, instead of such a configuration, the ventilation pipe 16 may be airtightly disposed near the surface of the biopile 15.

  As a configuration in which the ventilation pipe 16 is disposed in an airtight manner, for example, a configuration in which the biopile 15 is covered with an airtight sheet and the ventilation pipe 16 is disposed between the airtight sheet and the surface of the biopile 15 is conceivable.

  Further, in the present embodiment and the above-described modification, the vent pipe 16 is connected to the air introduction pipe 7 so that the warm air from the air introduction pipe is sent to the biopile 15 through the vent pipe 16. However, instead of such a configuration, the air introduction pipe 7 is connected to the hot water generator and the hot water is taken out from the water pipe connected to the hot water generator, and the water pipe is embedded in the biopile 15. Alternatively, they may be arranged near the surface thereof.

The schematic diagram of the purification system of oil pollution soil concerning a 1st embodiment. The figure which showed the high concentration pollution area and the low concentration pollution area which spreads to the circumference | surroundings. Schematic of the purification system of the oil pollution soil which concerns on 3rd Embodiment.

Explanation of symbols

1,31 Purification system for oil-contaminated soil 2 Indirect heating rotary kiln (heating furnace)
3 Bioremediation system
(Microbe decomposition treatment means)
12 Heated air outlet 15 Biopile 16 Vent pipe 19 Exhaust gas treatment device 21 High-concentration contaminated area 22 Low-concentrated contaminated area 23 Contaminated soil area 32 Direct heating rotary kiln (heating furnace)

Claims (4)

Among the contaminated soil areas containing oil, from the heating furnace that removes the oil by heat-treating the high-concentration contaminated soil excavated from the high-concentration contaminated area, and from the low-concentration contaminated area spreading around the high-concentration contaminated area the excavated lower concentration contaminated soil Ri Do from the biodegradation process means for removing the oil by biodegradation process, embedded in the piled in ridged as bio pile low concentration contaminated soil or in their surface The microbial decomposition treatment means is provided with a ventilation pipe arranged in an airtight neighborhood in the vicinity, and the heating furnace is an indirect heating type rotary kiln, and is arranged so as to be able to exchange heat with an exhaust gas pipe connected to the exhaust port of the indirect heating type rotary kiln. purification system of oil contaminated soil, characterized in that the air inlet pipe is communicatively connected to the outer cylinder of the indirect heating type rotary kiln is connected in communication with the vent tube . Of the contaminated soil area containing oil, a heating furnace that removes the oil by heat-treating heavy oil-contaminated soil excavated from the heavy oil-contaminated area, and light oil-contaminated soil excavated from the light oil-contaminated area the Ri Do from the biodegradation process means for removing the oil by microbial decomposition treatment is arranged sealingly embedded in or near the surface thereof to said light oil polluted soil in which served in the ridged as bio pile A ventilation pipe is provided in the microbial decomposition treatment means, and the heating furnace is an indirect heating rotary kiln, and is arranged so as to be able to exchange heat with an exhaust gas pipe connected to an exhaust port of the indirect heating rotary kiln. A system for purifying oil-contaminated soil, characterized in that an air introduction pipe connected to a cylinder is connected to the vent pipe . Among the contaminated soil areas containing oil, from the heating furnace that removes the oil by heat-treating the high-concentration contaminated soil excavated from the high-concentration contaminated area, and from the low-concentration contaminated area spreading around the high-concentration contaminated area the excavated lower concentration contaminated soil Ri Do from the biodegradation process means for removing the oil by biodegradation process, embedded in the piled in ridged as bio pile low concentration contaminated soil or in their surface The microbe decomposition means is provided with a ventilation tube arranged in an airtight manner in the vicinity, and the heating furnace is a direct heating rotary kiln so that heat exchange is possible with an exhaust gas pipe connected to the heating air discharge port of the direct heating rotary kiln. oil pollution, wherein the placed air inlet tube which is communicatively connected to the cylindrical body inner space of the direct heating type rotary kiln that is connected in communication with the vent tube Soil purification system. Among the contaminated soil areas containing oil, a heating furnace that removes the oil by heat-treating heavy oil-contaminated soil excavated from the heavy oil-contaminated area, and light oil-contaminated soil excavated from the light oil-contaminated area the Ri Do from the biodegradation process means for removing the oil by microbial decomposition treatment is arranged sealingly embedded in or near the surface thereof to said light oil polluted soil in which served in the ridged as bio pile The direct heating rotary kiln is provided with a ventilation pipe in the microbial decomposition treatment means and the heating furnace is a direct heating rotary kiln, and is arranged to be able to exchange heat with an exhaust gas pipe connected to a heating air discharge port of the direct heating rotary kiln. A system for purifying oil-contaminated soil, characterized in that an air introduction pipe communicated with the inner space of the cylinder is communicated with the vent pipe .

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