JP5165476B2 - Detoxification method for soil contaminated with organic compounds - Google Patents

Description

  The present invention relates to a method for detoxifying soil contaminated with organic compounds.

Conventionally, the following methods are known as methods for detoxifying soil contaminated with organic compounds.
(1) Detoxification method by high temperature incineration. This is to heat and process with a fossil fuel burner such as heavy oil or a high temperature electric furnace. However, there is a problem that a very large amount of energy is consumed and a large amount of carbon dioxide is discharged. In addition, since this method requires heating for a long time, there is a problem in terms of electricity and fuel costs, and in order to increase the processing efficiency, it is necessary to process in a large-scale plant. There is a problem that costs are incurred. In addition, this method cannot be easily applied to soil components with poor heat transfer and soil with high water content.Soil after drying has the effect of updraft during flame contact. There is a problem that it is difficult to reach a high temperature uniformly in the furnace.

  (2) Biological decomposition and detoxification treatment method using fungi or mold. This is to detoxify residual organic matter such as oil by using the ability to decompose bacteria. However, the environmental regeneration method using fungi is greatly affected by the environmental adaptability of the fungus, and there is a problem that the influence of soil quality and resident bacteria cannot be avoided.

  (3) A detoxification method using supercritical carbon dioxide. However, even if this method is a continuous type, it is difficult to treat contaminated soil on a large scale, and there is a problem that attention must be paid to the recovery or leakage of carbon dioxide gas.

  (4) A large-scale contaminated soil detoxification method, in which solvent or water is injected into the contaminated land to raise the pollution-causing oil and then remove it. This causes a problem that the possibility of spreading the contamination to other places increases because the held contaminants are released.

  Accordingly, an object of the present invention is to provide a method for detoxifying soil contaminated with an organic compound having a low environmental load.

  In view of the above technical situation, the present inventor has conducted intensive studies on a method for detoxifying soil contaminated with organic compounds, and as a result, soil containing organic compounds and a wood chip for auxiliary combustion in a self-burning carbonization device. The soil contaminated with organic compounds with a low environmental load is heat-treated in an oxygen-deficient state, and the organic compounds in the soil are pyrolyzed and carbonized together with the wood chips for auxiliary combustion. The present invention was completed by finding that it can be detoxified.

  That is, the present invention introduces soil containing organic compounds and wood chips for auxiliary combustion into a self-burning carbonization apparatus, heat-treats them in an oxygen-deficient state, and thermally decomposes organic compounds in the soil together with the wooden chips for auxiliary combustion. The present invention provides a method for treating soil containing an organic compound characterized by being carbonized.

ADVANTAGE OF THE INVENTION According to this invention, biomass resources, such as a bamboo thinning material, pruning material, and formwork waste material considered to be a woody waste domestically and abroad, can be utilized effectively.
Further, according to the present invention, fossil fuel consumption, that is, carbon dioxide emission can be kept low, and energy cost can be reduced.
Moreover, according to this invention, it is also possible to process on-site without transporting soil for a long distance.

  In the soil treatment method of the present invention, soil containing organic compounds and auxiliary wood chips are put into a self-burning carbonization apparatus, heat-treated in an oxygen-deficient state, and the organic compounds in the soil are pyrolyzed together with the auxiliary wood chips. And carbonized. The self-burning carbonization apparatus used in the present invention is not particularly limited, but is a substantially hermetic self-burning carbonization furnace body having a plurality of air introduction holes in the inner bottom, and the upper end of the furnace body standing upright in the furnace body. A self-combustion type comprising a heated exhaust pipe reaching the vicinity of the ceiling, the heated exhaust pipe having an exhaust introduction port communicating with the space inside the furnace at the lower part, and an upper part connected to an exhaust passage to the outside of the furnace A carbonization device is preferred.

  The self-burning carbonization apparatus preferably has a microcomputer-controlled automatic valve for adjusting the oxygen supply amount in that the reaction temperature can be adjusted as appropriate. The furnace exhaust pipe having a dry distillation hole and a processing container for containing contaminated soil And a secondary combustion chamber for burning the volatile components after pyrolysis. In addition, it is preferable that the processing container can be taken in and out by a crane or the like.

Further, in the present invention, as the carbonization apparatus, it is preferable that a SUS cylindrical assembly is erected in the furnace main body in terms of the efficiency of the detoxification treatment.
The self-burning carbonization furnace may include a filter that collects the generated gas.

Further, in the present invention, as the carbonization apparatus, an ignition chamber constituted by an inner bottom plate provided with the plurality of air introduction holes and an outer bottom plate disposed below the inner bottom plate at the bottom of the furnace body. It is preferable that the ignition chamber is provided with an air intake port and an ignition heat source introduction port.
Moreover, it is preferable to have a cover plate that opens and closes a material entrance provided in the upper part of the furnace body.
Moreover, it is preferable to have an air intake port for supplying air to the air introduction hole and an air supply amount adjusting means for the air intake port.

  In the present invention, as the self-burning carbonization apparatus, specifically, CEC-3600F type and CEC-3900F type manufactured by Charcoal Hoshin Co., Ltd. are preferable.

  The soil which is the target of the treatment method of the present invention is soil containing an organic compound, specifically, soil contaminated with an organic compound. Examples of the organic compound include crude oil, asphalt, heavy oil, lubricating oil, used lubricating oil, animal and vegetable oils, synthetic oils, light oil, kerosene, jet fuel, gasoline and naphtha components, crude oil, heavy oil, lubricating oil Oil, used lubricating oil, and light oil are preferred.

Among organic compounds, crude oil has a composition of carbon: 82 to 88%, hydrogen: 10 to 15%, sulfur: 6% or less, and the production area is not limited as long as the composition is within the above range. In other words, it refers to unrefined petroleum.
In addition, asphalt among organic compounds refers to straight asphalt which is a vacuum residue obtained by distillation from a vacuum distillation apparatus or blown asphalt which is blown with high-temperature air and has a high softening point.
Among organic compounds, heavy oil is a residual oil obtained by atmospheric distillation of crude oil or a heavy petroleum product obtained by processing the crude oil, and refers to one defined by JIS K 2205.

  In addition, among the organic compounds, the lubricating oil includes paraffinic mineral oil, naphthenic mineral oil, intermediate-based mineral oil and the like obtained by purification such as solvent refining and hydrorefining. Synthetic oils include hydrocarbon-based synthetic oils; monoesters, diesters, polyol esters (trimethylolpropane, pentaerythritol, dipentaerythritol, neopentyldiol esters, complex esters), polyglycol esters, glycerin esters, aromatic esters, etc. Ester oils; ether oils such as alkylated diphenyl ether, alkylated triphenyl ether, alkylated tetraphenyl ether, and alkylated polyphenyl ether; various silicone oils; various fluorine oils. The animal or vegetable oil may be an ester composed of a saturated fatty acid or an unsaturated fatty acid, or a mixture thereof. The lubricating base oil may be used alone or in combination of two or more, or may be a combination of mineral oil, synthetic oil and animal and vegetable oil. Further, engine oils, gear oils, hydraulic hydraulic oils, turbine oils, bearing oils, sliding surface oils, compressor oils, metalworking oils, insulating oils, greases and the like in which various additives are formulated may be used. Regardless of the type of additive added and the mixing ratio, it is applied to a wide range of lubricant base oils and lubricant products.

Further, among organic compounds, light oil is a petroleum product having a boiling point range of about 180 to 350 ° C. obtained by distillation of crude oil, and refers to one defined in JIS K 2204.
Among the organic compounds, kerosene is a petroleum product having a boiling point range of about 170 to 250 ° C. obtained by distillation of crude oil, and refers to one defined by JIS K 2203.

Among organic compounds, jet fuel includes JET-A defined by JIS K 2209, JET-A-1, a unified fuel standard for civil aircraft by the Petroleum Federation, JP-4 by the Defense Agency specifications and US military standards, JP -5, JP-8, etc.
Among organic compounds, gasoline is a petroleum product having a boiling range of about 30 to 220 ° C. obtained by distillation of crude oil, and refers to any of those defined by JIS K 2201, 2202, 2206.
Of the organic compounds, naphtha is a petroleum product having a boiling range of about 35 to 180 ° C. obtained by distillation of crude oil. Specifically, it is a light naphtha having a boiling range of 35 to 80 ° C. or a boiling range of 80 to 180 ° C. A heavy naphtha.

Further, when the soil containing these organic compounds is treated by the method of the present invention, gas may be generated. Therefore, as described above, the carbonization device is provided with a filter for collecting gas. preferable. Here, the organic compound that generates gas during carbonization includes volatile organic compounds such as first-class specific harmful substance components, halogenated hydrocarbon compounds, and third-class compounds in that they collect harmful gases. Examples include organic compounds selected from chemically synthesized pesticides such as specific hazardous substance components, and organic compounds selected from first-type specified hazardous substance components and third-type specified harmful substance components are more preferable.
In the present invention, the volatile organic compound and the halogenated hydrocarbon-based compound include a fluorocarbon gas raw material, a digestive agent, a degreasing detergent, a paint solvent, an extractant, a medicine (anesthetic), an insecticide, a refrigerant, a degreasing detergent, and a paint remover. , Dry cleaning solvents, etc., specifically, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene , cis - 1,2-dichloroethylene, 1,3-dichloropropene, dichloromethane, tetrachloroethylene, 1 , 1,1-trichloroethane, 1,1,2-trichloroethane, trichlorethylene, and compounds classified into the first class specific harmful substances selected from benzene are preferable.

  In the present invention, the chemically synthesized pesticides include herbicides, insecticides, soil fungicides, pesticides such as pest repellents and insulating oils contained in transcondensers, simazine, thiobencarb, thiraum, polychlorinated biphenyl and Preference is given to compounds classified as third-type specific hazardous substances selected from organic phosphorus compounds alone.

As wood chips for auxiliary combustion used in the present invention, wood and bamboo thinned wood, pruned pruners, sawmills and scraps and remaining materials from the process, wood chips accompanying construction, disposal of products using wood and bamboo Examples include various unnecessary materials such as waste materials that are generated by dismantling materials and houses, straw and rice husks that are agricultural wastes, and nut shells such as nut shells.
Also, there are no particular restrictions on the size and form of the wood chips, and there is no problem if the sizes are not uniform, but if it is too large, the loading density will be low, and the ventilation path in the load layer will be uneven. On the other hand, if it is too small, the gap between each other becomes small, and in order to inhibit the propagation of hot air from below to above, it is recommended that the longest part is about 1 to 20 cm, especially a bar-like one. .

In the method of the present invention, both soil containing organic compounds and wood chips for auxiliary combustion are put into a self-burning carbonization furnace, and the amount of soil is about 100 to 10,000 kg, preferably about 500 to 5000 kg. More preferably, it is about 900 to 1000 kg. The amount of the wood chip for auxiliary combustion is about 10 kg to 20000 kg, about 400 kg to 7500 kg, more preferably about 700 kg to 1000 kg. The mass ratio of the soil and the wood chip for auxiliary combustion is 1 to 0.1 to 1 to 2, preferably 1 to 0.8 to 1 to 1.5, more preferably 1 to 0.9 to 1 to 1.5. It is.
Moreover, in this invention, the organic compound in soil should just be 0-10 mass% with respect to soil by the point of a detoxification process efficiency, 0-6 mass% is preferable, and 1-6 mass% is more. preferable.

  The self-burning carbonizer heats in an oxygen deficient state. Here, the oxygen-deficient state refers to a state in which the amount of oxygen is small compared to the amount of oxygen in the atmosphere, which can be achieved by nitrogen replacement or air removal by decompression, and is preferably under reduced pressure. Specifically, a reduced pressure of 650 to 750 mmHg, particularly a reduced pressure of 650 to 730 mmHg is preferable.

  Moreover, as processing temperature, 800-1200 degreeC is preferable, and 800-1000 degreeC is more preferable in order to maintain the processing time mentioned later for a long time. As processing time, 12 to 36 hours are preferable and 18 to 30 hours are more preferable.

  According to the present invention, the organic compound in the soil is pyrolyzed and carbonized together with the wood chip for auxiliary combustion by the heat treatment.

  In the present invention, the soil containing the organic compound and earth and sand is contained in the furnace body for treatment, but in the point of simplicity of separating the treated carbide and soil, a SUS cylinder standing in the furnace body. It is preferable to treat it in the aggregate.

  In the present invention, it is preferable to ignite from the bottom of the furnace body. From the viewpoint of the efficiency of the detoxification treatment, ignition is performed from the bottom of the furnace body. More preferably, the treatment is accelerated by a temperature increase by at least one selected from red heat, vaporization heat, and self-heating decomposition of the cylinder.

  As a preferred example of the treatment method of the present invention, the cover plate of the self-combustion type carbonization furnace is opened, the soil is contained in the SUS cylindrical assembly standing in the furnace body, and the wood chip for auxiliary combustion is placed in the furnace body. Ignited from the bottom of the furnace body, and after ignition, the temperature of the soil is raised by at least one selected from red heat, vaporization heat, and self-heating decomposition of the heated exhaust pipe due to the hot air of the combustion exhaust gas passing through the heated exhaust pipe. There is a method in which spontaneous combustion occurs, the entire furnace space becomes a uniform high temperature state, the detoxification process is promoted, and the detoxification process is completed.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to this.

Example 1
The contaminated soil was treated using a CEC-3900F type manufactured by Charcoal Toyosin.
In this treatment, bamboo thinning chips with a length of 1 to 10 cm and a width of 1 to 3 cm are placed in an 800 kg furnace body as an auxiliary wood chip, and SUS containing 200 kg of contaminated soil containing 5 mass% crude oil and 1 mass% to 2 mass% moisture. Four cylinders were installed in the furnace body, and the furnace temperature after the temperature rise by the self-heating decomposition was set to around 900 to 1000 ° C., and the treatment was performed for 24 hours.
As a result, 740 to 750 kg of dried treated soil containing 800 kg of sand, gravel and stones were recovered, and the crude oil odor before the treatment was completely eliminated.
Even in the inspection with a photoionized ultrasensitive volatile organic compound (VOC) detector, the volatile component is 0.1 ppm or less which is the detection limit, and further, there is no detection of volatile organic component of oil from the obtained soil. For complete proof, Soxhlet extraction of the treated soil with an organic solvent followed by the presence of its contaminating organic components was confirmed by high-sensitivity cas chromatography-mass spectrometry, but it was below the detection limit and could be completely treated. It was judged.

Example 2
The treatment was performed in the same manner as in Example 1 except that 200 kg of contaminated soil containing 5 mass% of heavy oil and 1 mass% to 2 mass% of water was used.
As a result, 740 to 750 kg of dried treated soil containing 800 kg of sand, gravel and stones was recovered, and the heavy oil odor before the treatment was completely eliminated.
Even with inspection using a photoionized ultra-sensitive volatile organic compound (VOC) detector, the volatile component is below the detection limit of 0.1 ppm, and it is completely confirmed that there is no detection of volatile organic components of oil from the obtained soil. In order to prove this, the treated soil was subjected to Soxhlet extraction with an organic solvent, and the presence or absence of the contaminated organic component was confirmed by high-sensitivity cas chromatography-mass spectrum measurement. It was judged.

Example 3
The treatment was performed in the same manner as in Example 1 except that 200 kg of contaminated soil clay containing 5 mass% of used lubricating oil and 2 mass% of water was used.
As a result, 740 kg of 800 kg of dried treated white clay was recovered, and the lubricating oil odor before the treatment was completely eliminated. Even in the inspection with a photoionized ultra-sensitive volatile organic compound (VOC) detector, the volatile component is 0.1 ppm or less, which is the detection limit. In order to fully prove that there was no detection, Soxhlet extraction of the treated soil with an organic solvent was carried out, and the presence or absence of the contaminating organic component was confirmed by high-sensitivity cas chromatography-mass spectrum measurement. It was judged that it was completely processed.

Example 4
The treatment was performed in the same manner as in Example 1 except that 200 kg of contaminated soil containing 1 mass% to 2 mass% of light oil and 1 mass% to 2 mass% of water was used.
As a result, 760 to 780 kg of dried treated soil containing 800 kg of sand, gravel and stones were recovered, and the light oil odor before the treatment was completely eliminated. Even in the inspection with a photoionized ultrasensitive volatile organic compound (VOC) detector, the volatile component is 0.1 ppm or less which is the detection limit, and further, there is no detection of volatile organic component of oil from the obtained soil. For complete proof, Soxhlet extraction of the treated soil with an organic solvent followed by the presence of its contaminating organic components was confirmed by high-sensitivity cas chromatography-mass spectrometry, but it was below the detection limit and could be completely treated. It was judged.
Soil contaminated with gasoline and naphtha, which are higher volatile oils, was completely detoxified under the same conditions as in the above examples.

Example 5
Installed a cooler for cooling the gas generated in the CEC-3900F type produced by Charcoal Toyosinsha Co., Ltd. and treated the contaminated soil to treat 1 to 2 mass% heavy oil and 1 to 2 mass% heavy oil. The treatment was performed in the same manner as in Example 1 except that 200 kg of contaminated soil containing 1 mass% to 2 mass% of water was used.
As a result, 750 to 785 kg of dried treated soil containing 800 kg of sand, gravel and stone was recovered. The gas after collecting the filter was collected from the exhaust port and analyzed by high-sensitivity gas chromatography-mass spectrum measurement.
In addition, in order to fully prove that there is no detection of volatile organic components in oil from the obtained soil, Soxhlet extraction of the treated soil with an organic solvent, and its contaminating organic components by high-sensitivity cas chromatography-mass spectrometry However, it was below the lower limit of detection and was judged to have been completely processed.

Example 6
Installed a cooler for cooling the gas generated in the CEC-3900F model made by Charcoal Toyosinsha Co., Ltd. and treated the contaminated soil to treat 1 to 2 mass% heavy oil and 1 to 1 mass% organic phosphorus compound The treatment was performed in the same manner as in Example 1 except that 200 kg of contaminated soil containing 2 mass% and moisture of 1 mass% to 2 mass% was used.
As a result, 750 to 785 kg of dried treated soil containing 800 kg of sand, gravel and stone was recovered. The gas after collecting the filter was collected from the exhaust port and analyzed by high-sensitivity gas chromatography-mass spectrum measurement.
In addition, in order to fully prove that there is no detection of volatile organic components in oil from the obtained soil, Soxhlet extraction of the treated soil with an organic solvent, and its contaminating organic components by high-sensitivity cas chromatography-mass spectrometry However, it was below the lower limit of detection and was judged to have been completely processed.

Claims (4)

  The soil containing organic compounds and the wood chip for auxiliary combustion are put into a self-burning carbonization device equipped with a filter that collects gas generated in the self-burning carbonization device, and heat-treated at 800 to 1200 ° C in an oxygen-deficient state. A method for treating soil containing an organic compound, wherein the organic compound in the soil is pyrolyzed and carbonized together with a wood chip for auxiliary combustion.   The soil treatment method according to claim 1, wherein the oxygen-deficient state is a reduced pressure state. A self-burning carbonization apparatus includes a sealed self-burning carbonization furnace main body having a plurality of air introduction holes in an inner bottom portion, and a heated exhaust stack standing in the furnace main body and having an upper end reaching the vicinity of the ceiling of the furnace main body. The self-burning carbonization apparatus is characterized in that the heated exhaust pipe is provided with an exhaust introduction port communicating with the space in the furnace at the lower part and the upper part is a heated exhaust pipe connected to the exhaust passage to the outside of the furnace. The soil treatment method according to 1 or 2.   The soil according to any one of claims 1 to 3, wherein the organic compound is selected from crude oil, asphalt, heavy oil, lubricating oil, animal and vegetable oils, synthetic oils, light oil, kerosene, jet fuel, gasoline and naphtha components. Processing method.