JP4052536B2 - Purification equipment for highly viscous soil contaminated with microorganisms - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a highly viscous contaminated soil purification apparatus using microorganisms that purifies contaminants such as organochlorine compounds contained in the contaminated soil .
[0002]
[Prior art]
The soil may contain organochlorine compounds such as trichlorethylene and petroleum hydrocarbons such as heavy oil and gasoline. If such soil is left as it is, contamination of the above-mentioned organochlorine compounds will occur. Substances may diffuse into the environment through groundwater. Therefore, a predetermined purification process must be performed for such contaminated soil.
[0003]
On the other hand, research on bioremediation, a technology for degrading and detoxifying environmental pollutants using the activity of microorganisms, has been progressing and has been applied to the purification of marine pollution by crude oil. It has also been applied to contaminated soil.
[0004]
When purifying pollutants in contaminated soil using bioremediation, first excavate the contaminated soil and move the excavated contaminated soil to a temporary site, and then remove the pollutants in the excavated contaminated soil to microorganisms on the temporary site. Disassemble with. Then, after the pollutant is decomposed, a general procedure is to fill the treated soil back to the original position.
[0005]
[Problems to be solved by the invention]
However, in the case of highly contaminated soil, the activity of the aerobic degrading bacteria cannot be increased because of the poor air permeability of the contaminated soil, and it takes a long time to decompose the contaminants in the contaminated soil. In some cases, the microbial degradation itself is substantially impossible.
[0006]
In addition, by mixing and stirring quick lime in the contaminated soil, heat of hydration accompanying the chemical reaction between the moisture contained in the contaminated soil and quick lime is generated, and the contaminant is vaporized using this heat of hydration. However, in this method, the contaminated soil becomes strongly alkaline due to quick lime, and after being backfilled, the alkaline component diffuses into groundwater or the like, or into the ecosystem. There are concerns about adverse effects.
[0007]
The present invention has been made in consideration of the above-mentioned circumstances, and does not require post-treatment such as pH adjustment to affect or prevent the environment, and is efficient even in highly contaminated contaminated soil. An object of the present invention is to provide an apparatus for purifying highly viscous contaminated soil by microorganisms, which is capable of purifying contaminants .
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a highly viscous contaminated soil purification apparatus using microorganisms according to the present invention as described in claim 1, a container capable of containing contaminated soil containing a contaminant in an airtight state, and the container The agitation means for agitating the contaminated soil, decomposing bacteria introduction means for introducing the degrading bacteria that decompose the contaminants into the container, and air supply / exhaust means for supplying and exhausting the inside of the container, The stirring means is provided with a pair of stirring mechanisms having a stirring member projecting from the rotating shaft in parallel in the container, and the pair of stirring mechanisms are provided in one stirring mechanism so as to rotate in reverse with respect to each other. The rotation range of the stirring member extends to the vicinity of the rotation axis of the other stirring mechanism, and the degrading bacteria charging means is used as the cell supply pipe for the MO7 strain as the degrading bacteria stored in the cell suspension tank. To feed into the container with a pressure pump Configured, the supply and exhaust means is composed of air supply equipment and exhaust equipment, the supply of air facility configured to pump air into the container from the supply pipe with the air supply pump, exhaust pump the exhaust system The TCE, which is a contaminant contained in the gas, is drawn out from the exhaust pipe using the gas processing facility so that it can be collected by the gas processing facility.
[0012]
In the device for purifying highly viscous contaminated soil by microorganisms, contaminated soil containing pollutants is contained in a container to make it airtight, and then the aerated air is supplied and exhausted while the contaminated soil in the container is stirred by the stirring means. At the same time, a degrading bacterium that decomposes the pollutant is introduced into the container through the degrading bacterium introduction means.
[0013]
In this way, the pollutant is promoted to be vaporized from the contaminated soil by the aeration action by the air supply / exhaust means and the agitation action by the agitation means, and in a favorable aerobic environment by the aeration and agitation action described above. The activity of the decomposing bacteria added to the contaminated soil becomes high, and the pollutants in the contaminated soil are rapidly decomposed by the decomposing enzyme produced by the decomposing bacteria.
[0014]
Also, normally, even if it is a highly viscous contaminated soil that is difficult to ventilate, the air supply / exhaust means is aerated while the contaminated soil is agitated by the agitating means, so the contact between the contaminated soil and the surrounding gas is good. Rise. Therefore, the pollutants in the contaminated soil are quickly vaporized and recovered, and are efficiently microbially decomposed by the decomposing bacteria.
[0015]
The target pollutants include all those that can be microbially decomposed in an aerobic environment. As for the decomposing bacteria, an optimal one may be selected according to such pollutants.
[0016]
For example, if the pollutant is naturally occurring crude oil or the like, microorganisms that frequently inhabit the soil, such as Pseudomonas cells, can be used as they are. In addition, if the number of microorganisms capable of degrading pollutants does not exist in the contaminated soil, the microorganisms that can degrade the target pollutants from microorganisms living in other natural environments are isolated by screening, You may make it breed.
[0017]
On the other hand, if the pollutant is an artificially synthesized organic solvent such as trichlorethylene and it is difficult to obtain a microorganism that can be directly decomposed using it as the sole carbon source, it will co-metabolize, that is, decompose another substance. What is necessary is just to utilize the effect | action which performs an additional decomposition | disassembly at the time. For example, methane is supplied into the container together with air to activate methane-assimilating bacteria that exist in the soil or that are separately supplied to the soil, and decompose the organic solvent with the oxidase that the bacteria have. Aromatic assimilating bacteria (Pseudomonas) present in the soil or supplied separately in the soil by supplying a method, aromatic compounds such as phenol and toluene into the container via the degrading bacteria charging means or the air supply / exhaust means A method in which an aromatic compound is decomposed in a large number of bacteria belonging to the genus and the organic solvent is decomposed by co-metabolism at that time. In the present specification, the above methane and aromatic compounds are referred to as co-metabolites.
[0018]
In addition, although partially overlapping with the contents described above, as a degrading bacterium capable of microbially degrading trichlorethylene, Methylosinus tricosporium OB3 (Japanese Translation of PCT International Publication No. 4-501667, Japanese Patent Laid-Open No. Hei 5) -212371), Methylosinus tricosporium TUKUBA (Japanese Patent Laid-Open No. 2-92274, Japanese Patent Laid-Open No. 3-292970), Pseudomonus putida F1 (Japanese Patent Laid-Open No. 64-34499), Pseudomonas putida PH (Pseudomonus putida) BH (Fujita et al; Chemical Engineering, 39,6, p494-498, 1994), Pseudomonus putida UC-R5, UC-P2 (JP-A 62-84780), Pseudomonus putida (Pseudomonus putida) KWI-9 (Japanese Patent Laid-Open No. 6-70753), Pseudomonus mendocina KR1 (Japanese Patent Laid-Open No. 2-503866, 5-502593), Pseudomonus cepacia G4 (Japanese Patent Laid-Open No. 4-502277), Pseudomonus cepacia KK01 (JP-A-6-296711), Alcaligenes eutropus JMP134 (ARHarker Appl. Environ. Microbiol., 56, 4, 1179-1181, 1990), Alkalineus eutropus KS01 (JP-A-7-123976) ), Nitrosomonus europaea (D. Arciero et al. Biochem. Biophys. Res. Commun., 159, 2, 640-643, 1989), an ammonia oxidizing bacterium, Corynebacterium J1 (Japanese Patent Laid-Open No. 8-66182) is known.
[0019]
In addition, if MO7 stock | strain (international application number PCT / JP97 / 02872, international publication number WO98 / 07831, FERM BP-5624) is used, it can decompose | disassemble trichlorethylene directly more efficiently than the bacteria mentioned above.
[0020]
The vaporization and recovery process of pollutants and the input and decomposition process of degrading bacteria may proceed independently of each other. However, if such a vaporization and recovery process is preceded by the input and decomposition process, contamination by stirring aeration will occur. When the concentration of the pollutant is reduced in advance by vaporization and recovery of the substance and the decomposition effect by the decomposing bacteria is reduced to a concentration more easily appearing, the degrading bacteria are introduced.
[0021]
Therefore, it is possible to purify the pollutant by stirring aeration when the pollutant is at a high concentration, and microbial decomposition by degrading bacteria when the concentration is low, and perform the aeration and microbial decomposition at a concentration suitable for each, As a result, the overall purification efficiency can be greatly improved.
[0022]
The configuration of the agitating means is arbitrary, but the agitating means includes a pair of agitating mechanisms in which an agitating member protrudes from the rotating shaft, and the pair of agitating mechanisms. Are configured so that the rotation range of the stirring member provided in one stirring mechanism extends to the vicinity of the rotation axis of the other stirring mechanism, the contaminated soil is uniformly stirred and its viscosity is Even if this is high, it can be evenly contacted with air or the like.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a highly viscous contaminated soil purification apparatus using microorganisms according to the present invention will be described 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.
[0024]
FIG. 1 is an overall view showing a device for purifying contaminated soil by microorganisms according to the present embodiment. As shown in the figure, the contaminated soil purification apparatus 1 according to this embodiment inputs a highly viscous contaminated soil 2 containing trichlorethylene (hereinafter referred to as TCE) as a contaminant from an input hatch 19. In addition, the container 3 that can store the container in an airtight state, the stirring unit 4 that stirs the contaminated soil in the container, the decomposing bacteria input unit 5 that inputs the degrading bacteria that decompose TCE into the container 3, and the inside of the container 3 It comprises an air supply facility 6 and an exhaust facility 7 as air supply / exhaust means for supplying and exhausting air.
[0025]
The degrading bacteria charging means 5 contains decomposing bacteria such as MO7 strain (International Application No. PCT / JP97 / 02872, International Publication No. WO98 / 07831, FERM BP-5624) in the cell suspension tank 8, Can be supplied from the fungus body supply pipe 10 into the container 3 by the pressure feed pump 9. In addition, it is good to comprise so that a nutrient salt, a co-metabolite, etc. can be supplied together as needed so that the activity of decomposing bacteria may increase.
[0026]
The air supply facility 6 is configured to feed gas, mainly air, into the container 3 from the air supply pipe 18 using the air supply pump 11, but if necessary, conditions optimal for the growth of TCE-degrading bacteria are set. In consideration of this, it is preferable that the oxygen concentration, the gas temperature, and the like are appropriately set and the co-metabolites such as methane can be supplied together.
[0027]
The exhaust facility 7 is configured to draw out the gas in the container 3 from the exhaust pipe 14 using the exhaust pump 12 and to collect the TCE contained in the gas by the gas processing facility 13 using an adsorption action or the like on activated carbon. It is.
[0028]
In addition to the equipment described above, the contaminated soil purification apparatus 1 according to the present embodiment includes a belt conveyor 16 for transporting the soil from which TCE has been removed to the treated soil stock yard as treated soil 15, for example. ing. The belt conveyor 16 has its installation position adjusted so that the conveyor belt comes directly under the open / close discharge port 17 provided on the bottom surface of the container 3.
[0029]
FIG. 2 is a horizontal sectional view and a vertical sectional view showing the periphery of the container 3. As can be seen from these drawings, the stirring means 4 includes a pair of stirring mechanisms 21a and 21b each having a stirring member 25 radially projecting on the rotating shaft 22 and provided in the container 3 side by side. Gears 26, 26 are attached to the base end sides of the rotary shafts 22, 22 constituting the meshing gears and meshed with each other, and the output shaft 28 of the motor 27 is connected to the gear 26 on the side of the stirring mechanism 21b. 21b is configured to rotate in the reverse direction.
[0030]
Here, as can be clearly seen in FIG. 3, the stirring mechanisms 21a and 21b are configured such that the rotation range of the stirring member 25 provided in one stirring mechanism extends to the vicinity of the rotating shaft 22 of the other stirring mechanism. . The stirring member 25 is composed of a rod 23 protruding from the peripheral surface of the rotating shaft 22 and a substantially rectangular stirring plate 24 fixed to the tip thereof by welding or the like. The rotation range shown in FIG. The tip locus of the stirring plate 24 when the mechanisms 21a and 21b are rotated is shown.
[0031]
FIG. 4 is a detailed plan view of the stirring mechanisms 21a and 21b. FIG. 5 is a view as seen from the direction of the lines AA, BB and CC in FIG. Thus, it can be seen that the stirring mechanisms 21a and 21b do not interfere with each other, and the tip of the stirring member 25 provided in one stirring mechanism rotates in the reverse direction so as to pass near the rotation shaft 22 of the other stirring mechanism.
[0032]
Here, the stirring plate 24 is inclined so that when the stirring mechanisms 21a and 21b are rotated, the contaminated soil 2 is pushed out in the direction along the material axis of the rotating shaft 22, but the A in FIG. As can be understood by comparing the inclination angles of the stirring plate 24 when viewed from the direction of the A line and the BB line, the pushing directions by the stirring plate 24 are opposite to each other. Never move across.
[0033]
On the other hand, as shown in FIG. 3, the open / close-type discharge ports 17 and 17 provided on the bottom surface of the container 3 are rotatably joined to the container body side, and the soil that has been processed by opening the both sides to both sides is finished. Can be dropped right below.
[0034]
In the apparatus and method for purifying contaminated soil with microorganisms according to the present embodiment, first, the contaminated soil 2 containing TCE as a contaminant is introduced into the container 3 from the input hatch 19 to be airtight, While the contaminated soil 2 contained in the container 3 is agitated by the agitating means 4, air is supplied from the air supply equipment 6 and exhausted from the exhaust equipment 7 to ventilate the container 3.
[0035]
If it does in this way, vaporization of TCE from inside the contaminated soil 2 will be promoted by the aeration action by the air supply equipment 6 and the exhaust equipment 7 and the stirring action by the stirring means 4, and the TCE concentration in the contaminated earth 2 will decrease. Here, as is well understood in FIG. 5, the stirring by the stirring mechanisms 21a and 21b is a so-called two-axis reverse rotation method, and the contaminated soil 2 is uniformly stirred. That is, in a stirring means such as a conventional line mixer using an auger screw or the like, if the stirring object has a high viscosity, the stirring object only moves as a whole or adheres to the stirring means. Although there is a situation in which almost no agitation occurs, in the case of the biaxial reverse rotation method as in this embodiment, the contaminated soil 2 is agitated locally without moving as a whole, and homogeneous agitation is possible. Become.
[0036]
Note that the TCE vaporized from the contaminated soil 2 is withdrawn from the exhaust pipe 14 and then appropriately recovered by the gas processing facility 13.
[0037]
If the TCE concentration in the contaminated soil 2 is reduced to some extent, then, the decomposing bacteria stored in the cell suspension tank 8 with the above-described aeration and stirring maintained as they are are pumped from the cell supply pipe 10. 9 to supply into the container 3.
[0038]
In this way, the activity of the decomposing bacteria introduced into the container 3 becomes high under a good aerobic environment due to aeration and agitation action, and the TCE in the contaminated soil 2 is rapidly released by the decomposing enzyme from the decomposing bacteria. Degraded, the TCE concentration is further reduced. When the MO7 strain is used as a degrading bacterium, it may be possible to wait for the input of the degrading bacterium until the TCE concentration is reduced to, for example, 100 mg / kg or less.
[0039]
In such a microbial decomposition process, when gas is fed into the container 3 from the air supply facility 6, the oxygen concentration and gas temperature are set as appropriate for the growth of the TCE-degrading bacteria as necessary, and also as necessary. Then, co-metabolites, nutrient salts, and the like necessary for microbial decomposition are supplied into the container 3 through the decomposing bacteria input means 5 and the air supply facility 6.
[0040]
If the TCE concentration of the contaminated soil 2 is sufficiently lowered in this way, the open / close-type discharge port 17 of the container 3 is opened and dropped, and this is transported to the treated soil stock yard by the belt conveyor 16 as treated soil 15. .
[0041]
As described above, according to the apparatus and method for cleaning contaminated soil by microorganisms according to the present embodiment, the synergistic effect of the aeration action by the air supply equipment 6 and the exhaust equipment 7 and the stirring action by the stirring means 4 allows Vaporization from within the contaminated soil 2 is promoted, and the activity of decomposing bacteria added to the contaminated soil 2 becomes high under a good aerobic environment due to such aeration and stirring action, so that the TCE in the contaminated soil 2 is increased. The microorganisms are rapidly decomposed by the decomposing bacteria, and thus the TCE in the contaminated soil 2 can be efficiently purified.
[0042]
In particular, since the aeration is performed while the contaminated soil 2 is agitated by the agitating means 4, the contact with the surrounding gas is enhanced even with the highly viscous contaminated soil 2, and thus the TCE purification by vaporization recovery and microbial decomposition is achieved. It is possible to carry out reliably and efficiently even for highly viscous contaminated soil.
[0043]
In addition, since TCE purification does not use water or quicklime as in the prior art, post-treatment such as treating the slurry or adjusting the pH is not necessary, and it is possible to move quickly to operations such as backfilling. Therefore, soil purification can be performed in a short period of time without concern about the impact on the environment.
[0044]
In addition, according to the method for purifying contaminated soil by microorganisms according to the present embodiment, the vaporization recovery process by the air supply equipment 6 and the exhaust equipment 7 while stirring by the stirring means 4 is first performed for a certain period, and then the decomposition bacteria are input. Introducing the degrading bacteria by means 5, the TCE concentration is lowered in advance by TCE vaporization and recovery by stirring aeration, and the degrading bacteria are introduced when the degradation effect due to the degrading bacteria is lowered to a concentration more likely to appear. Therefore, it is possible to purify the TCE by stirring aeration when the TCE is at a high concentration and by microbial decomposition with degrading bacteria when the TCE is at a low concentration.
[0045]
Therefore, the stirring and aeration process and the microbial decomposition process are performed at concentrations suitable for each, and as a result, even when the number of microbial cells is small, TCE can be efficiently purified.
[0046]
In addition, according to the apparatus 1 for purifying contaminated soil with microorganisms according to the present embodiment, the stirring means 4 and the pair of stirring mechanisms 21 a and 21 b in which the stirring member 25 is protruded from the rotating shaft 22 are arranged in parallel in the container 3. In addition, since the pair of stirring mechanisms are configured so as to rotate in reverse to each other and the rotation range of the stirring member 25 provided in one stirring mechanism extends to the vicinity of the rotation shaft 22 of the other stirring mechanism. Without sticking the viscous contaminated soil 2 to the rotating shafts 22 of the stirring mechanisms 21a and 21b, it is possible to uniformly stir in the container 3 and evenly contact with air or the like.
[0047]
Therefore, the TCE contained in the contaminated soil 2 can be reliably purified by the above-described vaporization recovery by agitation and microbial decomposition.
[0048]
In the present embodiment, the vaporization recovery step is preceded by the decomposing bacteria input decomposition step. However, the method for purifying contaminated soil by microorganisms according to the present invention is not limited to such a procedure. The process and the microbial decomposition process using the decomposing bacteria may be performed simultaneously.
[0049]
Further, in the present embodiment, an example in which the present invention is applied to highly viscous contaminated soil has been described, but it goes without saying that the present invention can also be applied to low viscosity soil.
[0050]
【The invention's effect】
As described above, according to the apparatus for purifying highly viscous contaminated soil using microorganisms of the present invention, vaporization of contaminants is promoted by aeration and agitation action, and under a favorable aerobic environment due to such aeration and agitation action. As the activity of degrading bacteria added to the contaminated soil increases, the pollutants in the contaminated soil are quickly decomposed by the decomposing bacteria, and as a result, it is possible to efficiently purify the pollutants in the contaminated soil. Become. In particular, since the aeration is performed while stirring the contaminated soil by the agitation means, the contact property with the surrounding gas is increased even in the case of highly viscous contaminated soil, and thus the high-viscosity purification by evaporation recovery and microbial decomposition is achieved. It becomes possible to carry out reliably and efficiently even for contaminated soil.
[0051]
Further, according to the apparatus for purifying contaminated soil with microorganisms according to the present invention, even if the viscosity of the contaminated soil is high, the contaminated soil is reliably and evenly stirred in the container, and evenly contacted with air or the like. It is also possible to improve the certainty and efficiency of purification for highly viscous contaminated soil.
[0053]
[Brief description of the drawings]
FIG. 1 is an overall view of an apparatus for purifying contaminated soil by microorganisms according to the present embodiment.
FIGS. 2A and 2B are views around a container of a device for purifying soil contaminated with microorganisms according to the present embodiment, wherein FIG. 2A is a horizontal sectional view, and FIG. 2B is a vertical sectional view;
FIG. 3 is a vertical sectional view of the apparatus for purifying contaminated soil by microorganisms according to the present embodiment when viewed from another direction.
FIG. 4 is a detailed plan view of a stirring mechanism.
5 is a view as seen from the direction of the lines AA, BB, and CC in FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Contaminated soil purification apparatus 2 Contaminated soil 3 Container 4 Agitation means 5 Decomposing bacteria introduction means 6 Air supply equipment (supply / exhaust means)
7 Exhaust equipment (supply / exhaust means)
21a, 21b Stirring mechanism 22 Rotating shaft 25 Stirring member

Claims (1)

A container capable of containing contaminated soil containing a contaminant in an airtight state, a stirring means for stirring the contaminated soil in the container, and a degrading bacteria input means for introducing a degrading bacterium for decomposing the contaminant into the container And a supply / exhaust means for supplying and exhausting air to and from the container. The stirring mechanism is configured to rotate in the reverse direction to each other and the rotation range of the stirring member provided in one stirring mechanism extends to the vicinity of the rotation axis of the other stirring mechanism. The MO7 strain as the degrading bacterium contained in the suspension tank is configured to be supplied into the container with a pressure pump from a microbial cell supply pipe, and the air supply / exhaust means is configured with an air supply facility and an exhaust facility , From the air supply pipe using the air supply pump to the air supply equipment Serial configured to force air into the container, the collection can be the TCE is a pollutant gas of the exhaust system in the vessel using an exhaust pump included in the pull-out the gas from the exhaust pipe in a gas processing facility A device for purifying highly viscous contaminated soil with microorganisms , characterized by comprising .

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