JP2003053324A - Restoration method for soil polluted with petroleum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new restoration method for soil polluted by petroleum which is capable of effectively utilizing both of aerobic bacteria and anaerobic bacteria. SOLUTION: This restoration method for the soil polluted by the petroleum comprises supplying an aqueous solution replenished with oxygen together with microorganism nutrient sources to the soil polluted by the petroleum and cleaning the soil polluted by the petroleum by the indigenous microorganism, more preferably the indigenous aerobic bacteria and anaerobic bacteria.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for remediating petroleum-contaminated soil.

[0002]

[Prior Art] Japan's petroleum refining facilities, oil tanks, and gas stations are in a state of excess, so it is hoped that swift integration will be achieved at an appropriate scale. There is concern. Therefore, there is a need for an optimal method for remediating oil-contaminated soil according to the pollution status such as the type of oil, soil quality, and pollution scale. However, the restoration technology for petroleum-contaminated soil that has been developed or put into practical use is targeted at soil contaminated with light oil such as gasoline and light oil, and there are very few restoration technologies applicable to contaminated soil with heavy oil. It is in the present condition. As a technique for repairing such heavy oil-contaminated soil by physicochemical means, for example, there is an incineration treatment method, but it is said that there are many problems in operating cost in addition to the limited treatment capacity for large-scale pollution. . In addition, the bubble entrainment method using alkali and hydrogen peroxide has problems such as generation of costs by these chemicals and treatment of alkaline waste liquid containing oil, and super recyclone that grinds oil contaminated soil with water. In the system, there are problems in terms of cost and application to soil with a lot of clay.

As one of the methods for promoting the biological decomposition of the hardly decomposable substance contained in heavy oil, a microorganism having the ability to decompose the target hardly decomposable substance is added from the outside for purification. Bioaugmentation is being studied. However, according to bio-augmentation, it is necessary to add multiple types of microorganisms because the added microorganisms do not adapt well to the soil environment and a single microorganism cannot sufficiently decompose a wide variety of persistent substances. There are some problems such as being present. Furthermore, there is also a concern about the potential problem that microorganisms added to the soil environment from the outside may affect the ecosystem.

On the other hand, the biological purification technique called biostimulation utilizing indigenous microorganisms in soil is considered to be particularly advantageous in that it has little effect on the ecosystem, and the land farming method, Biopile method, slurry processing method, bioreactor method and the like are being studied. For example, a complex microbial community of indigenous microorganisms in contaminated soil,
As bioremediation techniques for purifying soil by proliferating and activating (hereinafter, sometimes referred to as “accumulation”), Japanese Patent Laid-Open Nos. 11-179336, 11-318435, and 10-34 are known.
No. 127 publication is cited.

Japanese Unexamined Patent Publication (Kokai) No. 11-179336 discloses a case where a complex microorganism group originally inhabiting soil is grown in two storage tanks to purify contaminated soil with petroleum (light oil). However, since aerobic culturing of complex microorganisms is carried out in the two storage tanks, the decomposition of petroleum depends on aerobic heterotrophic bacteria, resulting in uneven soil purification. Moreover, in this case, since the operation of storing the leachate containing soil microorganisms in the two water storage tanks, proliferating the oil-degrading microorganisms and then injecting the water is repeated, it is inevitable that the apparatus becomes large.

Further, Japanese Patent Laid-Open No. 11-318435 discloses a method of accumulating a special aerobic bacterium capable of decomposing the organochlorine pesticide PCNB from indigenous microorganisms originally inhabiting the soil. There is no disclosure about contaminated soil. Further, Japanese Patent Application Laid-Open No. 10-34127 discloses a technique of spraying activated sludge discharged when treating wastewater with activated sludge to soil to purify contaminated soil with a phenol compound. No purification by a complex microbial community of is disclosed. Thus, the technology for efficiently treating the purification of oil-contaminated soil contaminated with heavy oil is
It has never been realized.

[0007]

The first object of the present invention is to provide a novel method for remediating petroleum-contaminated soil which can utilize both aerobic and anaerobic bacteria. The second object of the present invention is a novel petroleum utilizing a resident microorganism of soil contaminated with petroleum, especially heavy oil, accumulated as a complex microorganism group including anaerobic microorganisms as well as aerobic microorganisms. The point is to provide a method for repairing contaminated soil.

[0008]

A first aspect of the present invention is characterized in that an aqueous solution supplemented with oxygen together with a microbial nutrient source is supplied to a petroleum-contaminated soil to purify petroleum pollutants by resident microorganisms. The present invention relates to a method for repairing oil-contaminated soil. The second aspect of the present invention is: (1) a step of supplying an aqueous solution supplemented with oxygen together with a microbial nutrient source to petroleum-contaminated soil to grow and activate resident microorganisms; and (2) an accumulated aerobic microorganism. Water containing a complex microbial group consisting of anaerobic microorganisms and / or
Or a step of purifying oil pollutants by mixing the soil with the oil-polluted soil, and to a method for repairing the oil-polluted soil. In the third aspect of the present invention, petroleum has a residual carbon content of 0.
The method for remediating petroleum-contaminated soil according to claim 1 or 2, which is a heavy oil containing 1% by weight or more or a heavy oil containing polycyclic aromatic hydrocarbons having a boiling point of 330 ° C or more. The residual carbon content is based on JIS K 2270. For details, refer to Minoru Fujita, “Petroleum Analytical Chemistry”, pages 40 to 41, issued by Petroleum Analytical Chemistry Research Institute, October 1, 1992. A fourth aspect of the present invention is that the microorganism contains both an aerobic microorganism and an anaerobic microorganism.
The present invention relates to any one of the methods for repairing oil-contaminated soil.

The individual oil-contaminated soils to be treated are
Various petroleum-degrading microorganisms are resident according to each soil environment. Therefore, these indigenous microorganisms are superior in environmental adaptability to petroleum-contaminated soil to be treated, as compared with exogenous petroleum-degrading microorganisms. For this reason, the utilization of aerobic and anaerobic microorganisms present there as resident microorganisms, especially when used in an accumulated state, the number of microorganisms is very large, and the purification reaction starts up. Was able to improve.

A preferred embodiment of the present invention will be described with reference to FIG. After burying petroleum-contaminated soil excavated from the pollution site by covering the periphery except the top with a sheet, drop an aqueous solution containing a microbial nutrient source from the top and apply the leachate to a waterproof sheet or pit laid on the bottom of the soil. Collect and store. The leachate contains a large amount of unused microbial nutrient sources, petroleum components and soil components that are easily soluble in water. It should be noted that the water-soluble petroleum component has a relatively low molecular weight and is relatively easily decomposed by microorganisms, but the heavy oil component, which is the main object of the method of the present invention, remains in the buried soil.

Here, in order to efficiently activate the activity of petroleum-degrading microorganisms in soil, it is necessary to supply microbial nutrient sources (for example, inorganic salts and vitamins) and water. As such a supply means, a means for circulating the stored leachate is usually adopted. Examples of the inorganic salts include those that serve as an inorganic nitrogen source and an inorganic phosphorus source. The nitrogen source may be one that is assimilated by microorganisms in the soil, but ammonia nitrogen such as ammonium chloride, ammonium sulfate or the like or nitrate nitrogen such as sodium nitrate, potassium nitrate or the like is preferable, and particularly ammonia nitrogen, such as ammonium nitrate is preferable. The inorganic phosphate compound, which is one of the inorganic phosphorus sources, may be one that can be assimilated by microorganisms in soil, and examples thereof include phosphate, perphosphate, metaphosphate, polyphosphate, and the like. These have the same purification promotion effect. Specific examples include potassium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium metaphosphate, potassium pyrophosphate, potassium tripolyphosphate, and the like. Among these, potassium dihydrogen phosphate and dipotassium hydrogen phosphate are economical. It is preferable from the viewpoint. In the method of the present invention, the pH of the soil is preferably 6 to 8 in order to produce the effect of adding the inorganic nitrogen source and the phosphorus source, and when the soil is acidic, it is neutralized with a basic agent. Preferably. As the basic agent, for example, calcium carbonate is preferable. The amount of calcium carbonate added varies depending on the acidity of the soil, but is about 1%, for example. When the soil is basic, it can be neutralized by adding ferrous sulfate, calcium sulfate, or the like.

Further, the presence of oxygen is required for accumulating aerobic microorganisms. The method of supplying oxygen is not particularly limited, but air can be blown into the stored leachate or the circulating liquid of the leachate with a compressor. In this case, it is desirable that the dissolved oxygen concentration in the leachate or the circulating fluid be a saturated concentration or a concentration close to the saturated concentration.
A guideline is about 7-9 ppm by weight at 0 ° C. When it is necessary to further increase the dissolved oxygen concentration, for example, by blowing pure oxygen instead of air, about 44 wt.
The dissolved oxygen concentration can be increased up to pm. Thus, one feature of the present invention is to supply oxygen to the oil-polluted soil as an aqueous solution. By adopting such a supply method, aerobic microorganisms work where the leachate reaches the soil quickly, When the leachate arrives late, oxygen is already consumed so much that anaerobic microorganisms act, and it is presumed that the decomposition of petroleum is efficiently performed by the synergistic action of these complex microorganism groups.

In order to purify oil-contaminated soil in this way, instead of covering the periphery other than the upper part with a sheet and burying the oil-contaminated soil as shown in FIG. 1, the periphery other than the upper part is covered with a sheet. A petroleum-contaminated soil may be filled with the soil, or a soil column may be formed as shown in FIG.

The composition of the microbial nutrient source is not particularly limited, but the ratio of carbon (C): nitrogen (N): phosphorus (P) is usually 10 to 1000: 1 to 100: 1, particularly 100: 1.
It is desirable to prepare an aqueous solution containing nitrogen or phosphorus so that the ratio becomes 0: 1. In addition, if necessary, organic substances such as salicylic acid for inducing enzymes of petroleum degrading microorganisms, metals and vitamins as micronutrients, yeast extract and corn steep liquor containing them, and petroleum are dispersed. It is also possible to add a surface active agent as a microbial nutrient source. These microbial nutrient sources may be supplied as an aqueous solution or may be supplied to the soil separately from the aqueous solution.

A specific method of determining the supplemental concentration of each nutrient will be described below with reference to one example. First, as a preliminary preparation, the carbon content ratio contained in each oil type is obtained in advance.
Next, the nitrogen-containing salt and phosphorus-containing salt to be used are selected. Carbon to nitrogen to phosphorus when carbon is 100 g (C to N to P ratio)
The addition amount of each salt is calculated from the molecular weights of the nitrogen salt and the phosphorus salt used so that the weight ratio of 100 to 10: 1 is obtained. Further, based on the carbon content of each oil species, the amount of each salt added per 100 g of each oil species is recalculated. Then, a list of the addition amounts of nitrogen salt and phosphorus salt corresponding to each oil type and the amount of oil is prepared. It should be noted that phosphorus salt uses two types of salts to have a pH buffering action so that the pH after the circulating fluid is prepared can be kept at 7, but the phosphorus amount is calculated as the sum of both salts. To do. Next, the actual amount added will be described. First,
Analyze the type and concentration of oil contained in the oil-polluted soil to be purified. When the oil type is determined, select the table corresponding to the oil type from the list created in the above procedure. Calculate the amount of oil in the entire treated contaminated soil based on the concentration analysis results. From the selected table, determine the addition amount of nitrogen salt and phosphorus salt corresponding to the oil amount. For other metal salts and yeast extract, prepare solutions with the concentrations shown in the table before use. Nitrogen salt and phosphorus salt may be directly mixed with the soil, and when the amount is small, they may be dissolved in other metal salts or yeast extract solution before use. Those that may be decomposed over time are added separately at each time.

As for the method of supplying water, after the aqueous solution containing the microbial nutrient source is first dropped, it may be appropriately replenished to the extent of supplementing the evaporated water. The flow rate of the aqueous solution is not particularly limited, but it is desirable to adjust the flow rate so as to be 0.1 to 2000 ml / min / soil-kg.

The pH of the leachate is also increased by the activity of microorganisms.
In the case of decrease in pH, the pH is maintained near neutral pH of 5 to 9, so that an alkaline aqueous solution can be appropriately added if necessary.

Further, under low temperature environmental conditions, it is desirable to keep the temperature of the leachate and the circulating fluid so as not to fall below 15 ° C., and it is necessary to improve the mixing state of the petroleum-contaminated soil and the circulating fluid. In some cases, it is desirable to occasionally mechanically stir the mixture of petroleum-contaminated soil and circulating fluid.

Next, another preferred embodiment of the present invention will be described in detail with reference to FIG. After filling the oil-contaminated soil excavated from the pollution site in a container with an open top to form a soil column, drop an aqueous solution containing a microbial nutrient source from the top and add a waterproof sheet or pit under the column. The leachate collection facility collects and stores the leachate from the column. The leachate is circulated in the same manner as in the above-described method of the present invention to accumulate complex microorganisms in the soil column, and then the soil and / or leachate in the soil column is taken out and returned to the petroleum-contaminated soil to be purified. Then, conventional biological purification such as land farming method and biopile method is performed. When accumulating a complex microorganism containing an anaerobic microorganism in the soil column, the same method as the method of FIG. 1 of the present invention described above can be used. Further, regarding the composition of the microbial nutrient source, the method of controlling water, the method of supplying oxygen, the method of maintaining PH, the method of controlling temperature, the method of mixing soil and leachate, etc., the same as the method of FIG. 1 of the present invention described above. Can be done.

In the present invention, it is important to utilize a complex microbial group of indigenous microorganisms. However, when the microbial preparations that can be used and the soil to be repaired have a good compatibility, these microbial preparations should be used in combination in the present invention. Is also possible. In the restoration of petroleum-contaminated soil according to the present invention, the pollutants to be restored are petroleum hydrocarbons, and examples thereof include crude oil, gasoline, light oil, kerosene, heavy oil, and lubricating oil. In particular, heavy oil or lubricating oil having a residual carbon content of 0.1% by weight or more, and low-boiling hydrocarbons are vaporized with the lapse of time after pollution, so that the residual carbon content is substantially zero. Crude oil that became 1% by weight or more of heavy oil, and boiling point of 330
The method for remediating petroleum-contaminated soil according to the present invention can be effectively used for heavy oil containing polycyclic aromatic hydrocarbons having a temperature of ℃ or higher. Examples of these components include normal paraffins and isoparaffins having 19 or more carbon atoms, and polycyclic aromatic hydrocarbons such as phenanthrene, anthracene, fluoranthene, pyrene, and benzo (a) pyrene, and derivatives thereof.

As the oil-contaminated soil, soil excavated from the contamination site, physicochemically pretreated soil, or the like can be used.

[0022]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. The method for measuring the number of bacterial cells using ATP in the examples is as follows. (1) 25 mmφ of 2 g of accumulated culture soil and 2 ml of distilled water
Put in a test tube and shake for about 5 minutes with a test tube mixer to separate the bacterial cells from the soil surface. (2) Centrifuge this solution at 65 G for 1 minute to separate the soil. (3) 1 ml of the centrifuged upper layer liquid is put into an 18 mmφ test tube containing 9 ml of distilled water and mixed with a test tube mixer to prepare a 10-fold diluted solution. Furthermore, this 10-fold dilution 1
ml is put into an 18 mmφ test tube containing 9 ml of distilled water and mixed with a test tube mixer to prepare a 100-fold diluted solution. This operation is sequentially performed to prepare a diluted solution up to 10 ⁵ times dilution. (4) Next, 20 μl of 10 to 10 ⁵ dilutions are placed in each 96-well black well. (5) In order to remove free ATP (adenosine triphosphate) derived from plants outside the cells, 50 μl of ATP removing solution is added to each and reacted for 30 minutes at room temperature. (6) Next, set this well in the light quantity measuring device. In order to elute the intracellular ATP present in each well,
60 μl of the extract as a cell membrane lysing agent is automatically added to each well and allowed to react at room temperature for 15 seconds. (7) Thereafter, 50 μl of a luminescent reagent, which is a mixed solution of luciferin and luciferase, is automatically added to each well,
The light emission amount is automatically measured after a certain period of time. The light intensity of each well is processed by computer and output. (8) From the light intensity result of each well, a light intensity value in a range in which the light intensity and the bacterial cell number are linearly correlated is selected, and the bacterial cell number is determined from a calibration curve of the previously obtained light intensity and bacterial cell number. (9) The dilution rate is further applied to obtain the bacterial cell concentration in the solution of (2) above. (10) The water content of the sampled accumulated culture soil was obtained by a drying method or the like, and the unit dry soil (g) was obtained from the result of (9)
Calculate the number of cells per unit. In the case of liquid culture, the number of cells per unit volume is displayed.

Examples 1 to 5 Using the microorganism collecting apparatus shown in FIG. 3, 300 g of heavy oil-contaminated soil (No. 1 in Table 2) or simulated contaminated soil (Table 2) was used in the column layer as shown in the conceptual diagram of FIG. Nos. 2, 4, 5, 6) in the above, and 400 ml of an aqueous solution of a microbial nutrient source having the composition shown in Table 1 is continuously circulated,
Accumulation of microorganisms and restoration of oil-contaminated soil were performed. During this process, the temperature was maintained at about 22 ° C., and the pH was adjusted to 7 with an appropriate alkaline aqueous solution. Further, by supplying air to the circulating fluid storage tank at a flow rate of about 5 ml / min, the dissolved oxygen concentration in the circulating fluid is close to the saturated concentration of about 8 pp.
It was maintained to be m. It should be noted that the accumulation of microorganisms is determined by measuring the concentration of microorganisms in the soil (the number of microorganisms per 1 g of soil) by ATP.
It was confirmed by calculating by a method and calculating a value (unit: times) when the microbial concentration before accumulation was 1. In addition, the soil restoration condition is as follows. After extracting the soil before and after the restoration treatment with carbon tetrachloride, the total hydrocarbon concentration (TP
H, unit: ppm) was measured, and the reduction rate (unit:%) of TPH before and after the treatment was calculated to find out. In this way, as a result of continuously accumulating microorganisms and repairing oil-contaminated soil for 2 months, the results shown in Table 2 were obtained, and the effectiveness of the present invention was confirmed. That is, according to the present invention, not only simulated soil contaminated with normal paraffin (No. 6) and light oil (No. 5) but also heavy oil contaminated soil (Nos. 1, 2, and 4) that was difficult to restore by the conventional technique. Also TP
H was significantly reduced, and a repair effect was recognized. In addition, since an increase in the number of microorganisms was observed in the process of accumulation of microorganisms and restoration of oil-contaminated soil, it is clear that a significant decrease in TPH was caused by accumulation of microorganisms. Further, as a comparative example, when pure water was used instead of the aqueous solution of the microbial nutrient source shown in Table 1 (Nos. 3 and 7), a remarkable decrease in TPH and an increase in the number of microorganisms were not observed. From this, it was confirmed that the remediation of the oil-contaminated soil according to the present invention was brought about by the accumulation of resident microorganisms in the soil.

[0024]

[Table 1]

[0025]

[Table 2]

Comparative Example 3 In order to make a comparison with Example 2 (No. 2 in Table 2), an aerobic culture was carried out using an Erlenmeyer flask having a capacity of 500 ml. The aqueous solution containing the microbial nutrient source used here is shown in Table 1, and 50 g of the same simulated polluted soil as in Example 2 adjusted to have a C heavy oil concentration of 10,000 ppm was used as the soil. . The weight ratio of the aqueous solution to the simulated contaminated soil was set to 30: 100 in consideration of the ratio of the aqueous solution to the soil in the column layer of Example 2. Further, in order to maintain aerobic conditions, the rotation speed of the rotary incubator was set to 220 rotations / minute, and stirring was continuously performed. As a result of carrying out the culture for 2 months under the aerobic condition in the same manner as in Example 2, the reduction rate of TPH in the soil was only 14%, and the decomposition of petroleum did not proceed so much. It was clearly inferior to the result of 2.

Example 6 400 g of actual contaminated soil (A) contaminated with heavy oil at 10,000 ppm was filled in the upper column tank of the microorganism accumulation apparatus shown in FIG. 400 ml of the microbial nutrient source aqueous solution having the composition shown was put therein, and continuously circulated in the manner shown in FIG. 2 to carry out microbial enrichment culture for 2 weeks. The soil cultivated for two weeks is added to 1600 g of the actual contaminated soil (A), which is an oil purification target, in an amount of 1 to 30 wt% and mixed. The cell concentration at that time should be 10 ⁶ cells / g dry soil. These mixed soils are made of polypropylene or stainless steel container (width 230 x length 135 x height 12
0 mm). Furthermore, nitrogen was added to the mixed oil in the soil in an amount of 10 wt% to the carbon weight, phosphoric acid to the carbon weight was 1 wt%, and the microbial nutrient source solution shown in Table 3 was added to the dry soil to be 15 wt%. Purification was performed in an incubator at 30 ° C. Soil in container 1 per week
It was stirred at a rate of once and air was supplied into the soil to carry out purification by the Land Farm method.

[0028]

[Table 3]

As a target experiment for comparison, the land farm method without addition of the column-accumulated culture soil was carried out to compare the effects of addition of the column-accumulated culture soil. These two
FIG. 4 shows the oil content reduction process and the bacterial cell concentration process in the purification experiment using various types of land farm method. The decomposition rate of TPH is (TP
H: Total Petroleum Hydroca
rbons) It's getting faster. By the way, in the case where the accumulated soil was added, the concentration reached such that only the hardly-biodegradable substance remained in about 6 weeks. Those without addition of column-accumulated soil reached almost the same decomposition rate in 20 weeks. This means that the purification was completed in 8 weeks in the present invention, which was carried out by using the microorganism accumulation technique including the accumulation period. On the other hand, the conventional method that does not use the microbial accumulation technique requires 20 weeks for purification, and the present invention can reduce the construction period by more than half compared to the conventional method, which is economically beneficial. .

Example 7 In order to compare the technique of the present invention with an aerobic liquid culture method generally used as a conventional microorganism accumulation method, an aerobic liquid culture was carried out by the following method. Specifically, as a conventional aerobic liquid culture method, 70 ml of a microbial nutrient source aqueous solution having the composition shown in Table 3 was placed in a 500 ml capacity shoulder flask, and 7 g of C heavy oil (10,000 mg / ml concentration) was added. . Furthermore, 0.2g of non-polluted soil was added,
120 shaking / min, 70 mm amplitude under aerobic conditions 2
Cultured for 0 weeks. On the other hand, the purification experiment according to the present invention was performed in the same manner as in Example 6. As the oil-contaminated soil, a simulated contaminated soil prepared with C heavy oil (soil for column accumulation culture and purified soil for land farm, C heavy oil concentration of 10,000 ppm) was used. Specifically, column accumulation culture was carried out for 2 weeks, and 400 g of the accumulated culture soil and 1600 g of C heavy oil simulated contaminated soil.
Into the polypropylene container described in Example 6,
Furthermore, a nutrient source was added in the same manner as in Example 6, and after mixing well, purification was carried out at 30 ° C. for 20 weeks. In addition, adjustment was performed 2 to 3 times / week so that the water content of the soil in the container was 15 wt%. FIG. 5 shows the oil content (TPH) decomposition process and the bacterial cell concentration process of the Landfarm method using the liquid culture and the container.

The decrease in oil content of both methods showed almost the same course, and the decomposition rate of C heavy oil at the 20th week was almost the same in both cases. When the oil components were analyzed, linear hydrocarbons among the saturated hydrocarbons were almost decomposed by the second week, and isoparaffins and cyclohexanes also decreased with time in both methods. On the other hand, polycyclic aromatic hydrocarbons start to be decomposed from the second week and are decomposed with the passage of time, but the land farm method using the column-accumulated culture soil of the present invention has a small number of rings with the passage of time. It was disassembled sequentially from the thing. However, it was found that polycyclic aromatic hydrocarbons that can be decomposed by the aerobic liquid culture method are limited. The analysis results of aromatic hydrocarbons at 20 weeks are shown in FIG. From this, the method of the present invention is one of the final judgments as to whether or not purification has been achieved.
It was found that saturated hydrocarbons and polycyclic aromatic hydrocarbons (those having 3 or less rings) existing in a liquid state at room temperature, which cause an oily odor, were almost decomposed.

[0032]

EFFECTS OF THE INVENTION (1) The invention of claim 1 is a petroleum which effectively utilizes microorganisms in petroleum-contaminated soil by setting a circulation in which aerobic microorganisms and anaerobic microorganisms can sufficiently function. The method of repairing contaminated soil has been provided (2) In the invention of claim 2, since it takes a considerable amount of time to reach a concentration at which the microorganism can be effectively utilized, a step until the microorganism reaches a predetermined concentration By separately providing as a culturing step, it becomes possible to supply high-concentration microorganisms to the reaction system, and as a result, the processing time has been greatly shortened.

[Brief description of drawings]

FIG. 1 shows a conceptual diagram of one embodiment of the present invention.

FIG. 2 shows a conceptual diagram of one mode of the first step of claim 2 of the present invention.

FIG. 3 shows a schematic view of a microorganism accumulation device.

FIG. 4 is a graph showing the state of soil purification in the case of the present invention to which the integrated culture soil of Example 6 is added and the conventional method of the Land Farm method in which no integrated culture soil is added.

FIG. 5 is a graph showing the state of soil purification in the case of the present invention to which the integrated culture soil of Example 7 is added and in the conventional Landfarm method in which no integrated culture soil is added.

FIG. 6 shows C heavy oil, oil contained in soil at 20 weeks of enrichment culture according to Example 7, and oil contained in soil at 20 weeks of conventional Landfarm method described in Example 7. A GC-MS chromatogram is shown.

   ─────────────────────────────────────────────────── ─── Continued front page    (71) Applicant 000186913             Showa Shell Sekiyu Co., Ltd.             2-3-2 Daiba, Minato-ku, Tokyo (72) Inventor Kenichi Kutsuka             Sumitomo Arata 4-3-9 Toranomon, Minato-ku, Tokyo             Toranomon Building Petroleum Industry Revitalization Center             In the center (72) Inventor Kenji Yamada             2-18-10 Takanawa, Minato-ku, Tokyo Japan Oil             Processing Co., Ltd. (72) Inventor Kazutoshi Furuta             2-18-10 Takanawa, Minato-ku, Tokyo Japan Oil             Processing Co., Ltd. (72) Inventor Suzuki Etsuo             1-1-1 Shibaura, Minato-ku, Tokyo Cosmo stone             Oil Co., Ltd. (72) Inventor Takao Matsumoto             Showa Che, 2-3-2 Daiba, Minato-ku, Tokyo             Within Le Petroleum Co., Ltd. (72) Inventor Shigenori Sakuma             Showa Che, 2-3-2 Daiba, Minato-ku, Tokyo             Within Le Petroleum Co., Ltd. F-term (reference) 4B065 AA99 AC20 BA23 BB04 BB40                       BC25 CA54 CA56                 4D004 AA41 AB02 CA15 CA18 CA19                       CA35 CC01 CC03 CC07 CC11                       CC15 DA03 DA10 DA20

Claims (4)

[Claims] 1. A method for remediating petroleum-contaminated soil, which comprises supplying an aqueous solution supplemented with oxygen together with a microbial nutrient source to petroleum-contaminated soil to purify petroleum pollutants with existing microorganisms. 2. A step of (1) supplying an aqueous solution supplemented with oxygen together with a microbial nutrient source to petroleum-contaminated soil to grow and activate resident microorganisms, and (2) accumulated aerobic microorganisms and anaerobic Water and / or containing a complex microorganism group consisting of microorganisms
Alternatively, a method of mixing oil with oil-polluted soil to purify oil pollutants, and a method for repairing oil-polluted soil. 3. The petroleum according to claim 1 or 2, wherein the petroleum is a heavy oil having a residual carbon content of 0.1% by weight or more or a heavy oil containing polycyclic aromatic hydrocarbons having a boiling point of 330 ° C or more. How to repair contaminated soil. 4. The method for repairing petroleum-contaminated soil according to claim 1, wherein the microorganism contains both an aerobic microorganism and an anaerobic microorganism.