JP2005205299A - Method for purifying contaminated soil and contaminated water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method which enables an efficient reduction in high concentrations of volatile organic chlorine compounds (tetrachloroethylene etc.) at a low cost, and the purification of soil and ground water contaminated with the volatile organic chlorine compounds. <P>SOLUTION: The purification method of the contaminated soil or contaminated water sequentially performs a process for treating contaminated soil or the like with anaerobic microorganisms, a gas ventilation process, and a treating process with aerobic microorganisms. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for purifying soil or water contaminated with volatile organochlorine compounds.

  Tetrachloroethylene (hereinafter referred to as “PCE”), an organic chlorinated solvent, has excellent solubility, volatility, and non-flammability characteristics, and is used for dry cleaning, chlorofluorocarbon gas production materials, degreasing and cleaning of metal parts, and fiber refining. It has been used for processing. On the other hand, PCE has been confirmed to be carcinogenic by animal experiments and has also been reported to cause damage to the central nervous system, liver and kidney.

  Trichlorethylene (hereinafter referred to as “TCE”), which is also a volatile organic chlorine compound, is mainly used as a cleaning agent in the manufacture of semiconductors due to its volatility and excellent solubility. Of toxicity.

  As described above, volatile organochlorine compounds such as PCE and TCE, which have a large amount of use but are highly toxic, have a drawback that they are chemically stable and hardly decomposed in the environment. Therefore, various methods for treating these volatile organochlorine compounds that have flowed out of factories and the like into the surrounding environment and contaminated soil and groundwater have been studied.

  For example, Patent Document 1 discloses that an organic chlorine compound contaminated with soil is sucked and treated as a gas by heating the polluted gas supplied to the activated carbon adsorption tower using the heat of the exhaust gas from the vacuum pump. An invention of a purification treatment facility capable of efficiently adsorbing a chlorine compound is disclosed. However, with such a vacuum extraction method, it is extremely difficult to reduce the organochlorine compound below the environmental standard value. In addition, since enormous energy is required to gasify the organic chlorine compound contained in the soil so as to be vacuumed, it is not preferable from the viewpoint of cost reduction and energy saving.

  Therefore, in recent years, attention has been paid to the development of microorganisms (bioremediation), which can be carried out at a lower cost under milder conditions and is excellent from the viewpoint of energy saving.

  For example, Patent Document 2 describes a technique in which PCE is first converted to TCE by an anaerobic microorganism, and then this TCE is decomposed by an aerobic microorganism. However, in general, it is difficult to decompose TCE exceeding a concentration of 50 mg / L by treatment with aerobic microorganisms. In fact, the examples described in Patent Document 2 disclose data for converting PCE at a concentration of 1 to 160 mg / L into TCE by anaerobic microorganisms (see FIG. 1 of Patent Document 2), while TCE is related to TCE. Describes only data obtained by processing less than 2 mg / L (see FIG. 4 of Patent Document 2). Moreover, according to the knowledge by the present inventors, when the TCE concentration reaches about 80 mg / L as in Examples described later, the TCE degradation rate of aerobic microorganisms decreases.

Patent Documents 3 and 4 disclose a method for purifying soil contaminated with an organic chlorine compound by alternately repeating a treatment with an anaerobic microorganism and a treatment with an aerobic microorganism a plurality of times. According to the method, for example, a plurality of operations in which soil contaminated with a high concentration of PCE is treated with anaerobic microorganisms and treated with aerobic microorganisms before the concentration of TCE generated as a result of the treatment increases excessively. It is considered that soil contaminated with high-concentration organochlorine compounds can be purified by repeating the process. However, it takes too much time, and it is difficult to adopt the method if actual processing is taken into consideration.
JP-A-7-328386 (Claim 1) JP-A-12-102377 (Claims 1 and 2 and FIGS. 1 and 4) JP 2003-164849 A (Claim 1) JP 2003-164850 A (Claim 1)

  In actual pollution sites, hot spots (highly contaminated areas) exist in the unsaturated soil in the vicinity of the pollution source and in the aquifer area immediately below it, so that high-concentration organochlorine compounds are efficiently treated. Technology is anxious.

  However, as described above, although methods such as vacuum extraction and bioremediation have been known to purify soil contaminated with organochlorine compounds, low-cost and highly contaminated soil has been obtained at a low cost. No method has been known that can be efficiently processed.

  Therefore, the problem to be solved by the present invention is to provide a method capable of efficiently purifying soil and groundwater contaminated with a high concentration of volatile organic chlorine compounds at low cost.

  In order to solve the above-mentioned problems, the inventor has paid attention to a method of alternately using anaerobic microbial treatment and aerobic microbial treatment among bioremediations at low cost and low energy consumption, and has conducted extensive research. As a result, combining these treatments with gas aeration treatment can effectively reduce the concentration of organochlorine compounds with a relatively small number of chlorine, and in the treatment of soil contaminated with high-concentration organochlorine compounds. However, the present invention has been completed by finding that aerobic microorganism treatment is possible.

  That is, the method for purifying contaminated soil or contaminated water according to the present invention is a method for purifying soil or water contaminated with organochlorine compounds, and the soil or water is subjected to anaerobic dechlorination microorganisms under anaerobic conditions. A process of treating the gas (hereinafter referred to as “anaerobic microorganism treatment process”), a process of aerating gas into the soil or water after the anaerobic microorganism treatment process (hereinafter referred to as “gas aeration process”), and the gas After the aeration step, the method includes a step of treating the soil or water with an aerobic decomposing microorganism (hereinafter referred to as “aerobic microorganism treatment step”).

  In the purification method, it is preferable that the gas diffused in the gas aeration process is processed by a gas processing means. This is because it is not preferable that the volatile organic chlorine compound contained in the emitted gas is released into the atmosphere, so that it is captured and processed by the gas processing means.

  Moreover, the aspect which performs the process which ventilates gas in the said soil or water, or the process which processes the said soil or water with an aerobic decomposition microorganism before the said anaerobic microorganism treatment process is also suitable. This is because, in the case of complex contamination with a plurality of organic chlorine compounds, the efficiency of anaerobic microorganism treatment can be further enhanced by removing organic chlorine compounds having a relatively small number of chlorines from the reaction system. Incidentally, when the concentration of the organic chlorine compound having a relatively small number of chlorine is relatively high, it is preferable to ventilate the gas, and when the concentration is relatively low, treatment with aerobic microorganisms in addition to gas aeration is also possible. Can do.

  Furthermore, it is also preferable to perform the anaerobic microorganism treatment step, the gas aeration step, and the aerobic microorganism treatment step at least twice. This is because it is possible to efficiently purify soil contaminated with a higher concentration of an organic chlorine compound, and it is possible to efficiently treat the organic chlorine compound to a lower concentration.

  According to the method for purifying contaminated soil or contaminated water according to the present invention, even soil and groundwater contaminated with volatile organochlorine compounds having a concentration as high as that which could not be treated by the conventional method is low in cost. The purification process can be performed efficiently. Therefore, the method of the present invention is extremely useful industrially as it can purify soil contaminated with a high concentration of volatile organochlorine compounds and can be applied to actual purification treatment.

  Hereinafter, embodiments of the present invention and effects thereof will be described.

(1) Anaerobic microorganism treatment step In the purification method of the present invention, a step of treating soil or water contaminated with an organic chlorine compound with an anaerobic dechlorinating microorganism under anaerobic conditions is performed. In this step, a highly chlorinated volatile organic chlorine compound such as PCE is dechlorinated and decomposed into an organic chlorine compound having a relatively small number of chlorine such as TCE or dichloroethylene (hereinafter referred to as “DCE”).

  The “organochlorine compounds” used here are industrially used as solvents, cleaning agents, etc., and have high toxicity, but are not easily decomposed in the environment due to their high stability, and exist in high concentrations. It is the one that was difficult to be decomposed by the conventional method. Examples of such organic chlorine compounds include those highly substituted with chlorine such as PCE, carbon tetrachloride, 1,1,1-trichloroethane.

  The “anaerobic dechlorination microorganism” to be used is not particularly limited as long as it can dechlorinate the volatile organochlorine compound. For example, the genus Desulfitobacterium which has demonstrated the dechlorination ability of PCE. And sulfate-reducing bacteria. Such anaerobic dechlorinating microorganisms may be added to the reaction system prior to the anaerobic microorganism treatment step by adding an appropriate species or microbial group, but may activate and utilize indigenous microorganisms that live in the soil or water. Good.

  In addition, nutrient sources (nitrogen nutrient sources, carbon nutrient sources, organic acids, inorganic salts, vitamins, etc.) necessary for the growth of anaerobic dechlorinating microorganisms are added to the reaction system. The type, amount added, and appropriate temperature and pH range depend on the anaerobic dechlorinating microorganism used, and may be adjusted accordingly.

  When the treatment target is contaminated soil, the soil is collected, and an anaerobic dechlorinating microorganism is added to the anaerobic condition in the reactor to dechlorinate highly chlorinated organochlorine compounds. Can be The “reactor” used here is preferably capable of switching between anaerobic conditions and aerobic conditions, and can be used without particular limitation as long as it is equipped with a gas aeration means to be described later. However, those that can be sealed to maintain anaerobic conditions are preferred, and those that are equipped with stirring means are preferred to enable efficient dechlorination.

  When the treatment target is groundwater, or when the soil quality in the vicinity is improved by treating the groundwater, the groundwater is pumped from the pumping well, anaerobic microorganism treatment process, gas aeration process, and aerobic microorganism treatment What is necessary is just to process a process and to return treated groundwater from an injection well. In this case, since it is not necessary to excavate the soil, it can be processed at low cost. In addition, necessary anaerobic dechlorinating microorganisms and nutrient sources can be injected into the line.

Abundance in amount and reaction system of anaerobic dechlorination microorganisms may vary depending on such (pollutant concentration of the organic chlorine compounds) the amount and degree of contamination of soil or the like to be treated, for example, 10 ⁹ equivalent bacterial solution per 1mL of What is necessary is just to add about 0.1-10 mass% with respect to soil or groundwater. However, it is necessary to appropriately adjust the addition amount and the existing amount depending on the actual processing state.

  As a means of anaerobic conditions, it can be mentioned that the reaction system is filled with anaerobic gas, but when the reaction system can be kept sealed, it gradually becomes anaerobic due to respiration of the aerobic microorganisms that coexist, It may be simply maintained in a sealed state. Incidentally, the “anaerobic condition” herein refers to a state where the oxygen concentration is within a range where anaerobic dechlorinating microorganisms can grow and an organic chlorine compound can be dechlorinated, for example, a redox potential of minus 50 mV or less. Shall.

  The treatment time of the anaerobic microorganism treatment process depends on the amount of soil to be treated, the degree of contamination, etc., but the progress of treatment can be determined by measuring the type and concentration of organochlorine compounds released into the soil sample and gas phase. It can be grasped and moved to the next step when decomposition of the highly chlorinated organochlorine compound is completed (when the concentration of the organochlorine compound falls below the environmental standard value). However, if the initial organochlorine compound concentration is extremely high, the next step may be started when highly chlorinated organochlorine compound remains in order to achieve more efficient treatment. .

(2) Gas aeration process In the method of the present invention, after the anaerobic microorganism treatment process, a process of aeration of gas into soil or water is performed. The purpose of this step is to reduce the concentration of the organochlorine compound dechlorinated by the anaerobic microorganism treatment step. This is because the treatment by the aerobic microorganism treatment step described later is possible or more efficient.

  The type of gas to be ventilated is not particularly limited, but the purpose of this process is to volatilize organochlorine compounds from contaminated soil etc. to reduce their concentration, so naturally it does not contain volatile organochlorine compounds. It is necessary to use air from the viewpoint of cost. In addition, the use of an aerobic gas such as air as the gas also has the advantage that it can be quickly transferred to the aerobic microorganism treatment step described later.

  This step may be performed as it is in the container in which the anaerobic microorganism treatment step is performed, or another container or the like may be used. For example, after performing the anaerobic microorganism treatment using a technique such as the in-situ groundwater circulation method, and treating the groundwater itself and its surrounding soil, the soil is excavated and placed in a container, and then a gas aeration treatment, etc. May be performed.

  The gas released in this step is preferably processed by a gas processing means. This is because volatile organic chlorine compounds are not released into the atmosphere. The “gas treatment means” used here is not particularly limited as long as it can adsorb and recover, decompose, etc. volatile organic chlorine compounds, but as the adsorption means, for example, an adsorption tower using activated carbon or an adsorption resin, A filter can be mentioned. Further, the adsorbed volatile organic chlorine compound may be decomposed by a catalyst supported on a filter, heat or light, or may be biodegraded.

  The means for venting the gas is not particularly limited as long as it is generally used by those skilled in the art. For example, a blower or the like can be used. Moreover, it is preferable to stir soil and groundwater during gas aeration. This is to volatilize the organic chlorine compound more efficiently.

  The gas aeration step is continuously performed until the concentration of the organochlorine compound to be treated in the aerobic microorganism treatment step described below is equal to or lower than the concentration at which treatment in the aerobic microorganism treatment step is possible. For example, when treating soil contaminated with PCE, PCE is decomposed into TCE, DCE, etc. by dechlorination in the above-mentioned anaerobic microorganism treatment process. Since the concentration that is possible or efficient is about 50 mg / L or less, the gas aeration process continues until the concentration of TCE or the like falls below this.

(3) Aerobic microorganism treatment process After the gas aeration process, a process of treating with an aerobic decomposing microorganism is performed under aerobic conditions. The organochlorine compound that has been dechlorinated in the anaerobic microorganism treatment step and whose concentration has been reduced in the gas aeration step is finally decomposed into carbon dioxide, water, and the like in this step.

  The “organochlorine compound” decomposed in this step is dechlorinated in the anaerobic microorganism treatment step. For example, in the case of soil contaminated with PCE, it is decomposed into TCE, DCE, etc. by anaerobic microorganism treatment, and it is these TCEs, etc. that are decomposed in this step.

  As the “aerobic degrading microorganisms” in this process, aerobic microorganisms living in the soil or groundwater can be used as they are, but newly added degrading microorganisms or groups of microorganisms can be added depending on the purpose. Also good.

  As in the anaerobic microorganism treatment step, nutrient sources necessary for the growth of aerobic microorganisms are added to the reaction system. The type, amount added, and appropriate temperature and pH range may be appropriately adjusted depending on the aerobic decomposing microorganism to be used. The amount of aerobic microorganism added may be appropriately adjusted according to the results of the sample analysis (the type and concentration of the remaining organochlorine compound). Moreover, the carbon nutrient source which should be added can also be supplied by ventilating methane gas etc., for example. However, when using flammable gas, it is necessary to suppress the concentration to such an extent that it does not ignite.

  The place for carrying out this step is not particularly limited, but can be carried out as it is in a container or the like in which the anaerobic microorganism treatment step or the gas aeration step is carried out. Moreover, when implementing this process, it is preferable to stir soil etc.

  In order to make the reaction system aerobic, an aerobic gas such as air is used as the gas in the gas aeration step, or an aerobic gas and a peroxide substance (hydrogen peroxide solution, potassium permanganate, etc.) are used. There is a method of using inputs together.

  The treatment time of the aerobic microorganism treatment process depends on the amount of soil to be treated, the degree of contamination, etc., but as in the case of the anaerobic microorganism treatment process, the progress of the treatment is ascertained by sample analysis, and the organic chlorine compound It may be completed when the decomposition of (when the concentration of the organochlorine compound becomes lower than the environmental standard value). However, when the initial organochlorine compound remains at the end, the above steps (anaerobic microbial treatment step, gas aeration step, and aerobic microbial treatment step) may be repeated again. Repeating the above steps a plurality of times also has the advantage that the concentration of harmful organochlorine compounds can be further reduced.

(4)
Before the anaerobic microorganism treatment step, a step of aeration of gas into soil or water may be performed. For example, in the case of combined contamination of PCE, TCE and DCE, anaerobic microbial treatment can be made more efficient by reducing the concentration of TCE and DCE which are more volatile but difficult to serve as a substrate for the anaerobic microbial treatment process. It is because it can be performed. Such a gas aeration process can be carried out under the same conditions as the gas aeration process described in (2) above.

  Moreover, the aspect which performs the process of processing soil or water by an aerobic decomposition microorganism before the said anaerobic microorganism processing process is also suitable. Although it is still effective in the case of complex contamination, in this case, the concentration of organochlorine compounds (for example, TCE and DCE) capable of aerobic microbial degradation is relatively low, and aerobic microbial treatment is possible. Should be adopted in some cases.

  Such an aerobic microorganism treatment step can be performed under the same conditions as the aerobic microorganism treatment step described in (3) above.

  Hereinafter, the present invention will be described in more detail by way of examples, but the scope of the present invention is not limited thereto.

Example 1 Isolation of Anaerobic Microorganism First, an inorganic salt medium was prepared with the composition shown in Table 1, and a basic medium containing sodium n-butyrate as a main carbon source with the composition shown in Table 2 was used. It was created.

  18 mL of this basal medium was placed in a 25 mL vial and purged beforehand with nitrogen. Sampling the field soil as a bacterial species source, inoculating 0.1 g of the soil into a vial, sealing the vial, injecting PCE to an equivalent of 1 mg / L, and performing shaking culture at 30 ° C. and 150 rpm It was. After culturing for 5 weeks, the headspace gas in the vial was analyzed by a gas chromatograph (ECD detector, hereinafter referred to as “GC / ECD”) to confirm the resolution of PCE. In addition, the purity of the bacteria was increased by repeatedly inoculating by the same method, and finally sulfate-reducing bacteria having PCE resolution were isolated as colonies on the plate medium. This sulfate-reducing bacterium had the ability to degrade PCE to TCE.

Example 2 Separation of aerobic microorganism group 5 mL of the inorganic salt medium prepared in Example 1 was placed in a 70 mL capacity vial. Collect sludge from a wastewater treatment facility as a bacterial species source, inoculate 0.4 mL of the soil into a vial, seal the vial, replace 13 mL of the gas phase in the vial with methane gas, and TCE equivalent to 1 mg / L Then, the mixture was shaken and cultured at 30 ° C. and 150 rpm. After culturing for 10 days, the headspace gas in the vial was analyzed by GC / ECD to confirm the resolution of TCE. Furthermore, by performing transplanting twice by the same method, the purity of the bacteria was increased, and an enriched culture solution containing aerobic microorganisms capable of stably decomposing TCE was obtained.

Example 3 Purification treatment of PCE-contaminated soil by the method of the present invention (1) Anaerobic microorganism treatment step 10 g of field soil (non-contaminated / air-dried soil) was placed in a 125 mL capacity vial and the basic prepared in Example 1 above. 90 mL of medium was added. Next, inoculated with bacterial suspension 1 mL (bacterial number ¹⁰⁹ or equivalent) was isolated in Example 1 anaerobic dechlorination microorganisms (sulphate-reducing bacteria), after sealing, the concentration in the solution becomes equivalent 100 mg / mL PCE was injected in the same manner. When the vial was shake-cultured at 30 ° C. and 150 rpm, the PCE concentration was below the detection limit (0.005 mg / L or less) on the sixth day after the start of the culture.

(2) Gas aeration process step Next, the lid of the vial bottle was removed, the stone at the tip of the air pump was inserted into the vial bottle, and aeration was continuously performed from the stone with an air amount of 0.5 vvm (50 mL / min). . A small amount of culture solution was sampled from the vial over time, and aeration was continued for 24 hours while analyzing the headspace gas by GC / ECD. In addition, in order to make up for water evaporated during the gas aeration treatment, distilled water was appropriately replenished so that a predetermined amount of water was maintained.

(3) Aerobic microorganism treatment process After aeration for 24 hours, 1 mL of an aerobic microorganism group accumulation culture solution prepared in Example 2 was inoculated. After inoculation, the gas was switched from air to methane gas (air 97.5% + methane 2.5%) as a carbon nutrient source for the aerobic microorganism group and continuously aerated (0.5 vvm). Again, a small amount of culture was sampled from the vial over time, and the concentrations of PCE and TCE in the headspace were analyzed by GC / ECD. Distilled water was appropriately replenished to make up for water evaporated by aeration of gas (air + methane), and adjustment was made to maintain a predetermined amount of water.

  The above results (PCE and TCE concentrations) are shown in FIG.

Comparative Example 1 Anaerobic Microbial Treatment + Aerobic Microbial Treatment After the anaerobic microbial treatment in Example 3 above, an aerobic microbial treatment was performed without performing a gas aeration treatment. That is, after (1) of Example 3 above, using a syringe, 1 mL of an aerobic microorganism group accumulation culture prepared in Example (2) above, 20 mL of oxygen gas and methane gas were injected into each vial. The headspace gas was sampled almost every day and analyzed with a GC-FID (gas chromatograph-hydrogen flame ionization detector) and a trace oxygen meter. At this time, when the oxygen concentration or methane concentration in the head space was less than 5%, 20 mL of oxygen gas and methane gas were appropriately added to prevent each concentration from falling below the required amount. In addition, a small amount of culture solution was sampled from the vial over time, and the concentrations of PCE and TCE in the headspace were analyzed by GC / ECD. The results are shown in FIG.

Comparative Example 2 Anaerobic microorganism treatment + gas aeration treatment After the anaerobic microorganism treatment in Example 3 above, only the gas aeration treatment was performed. That is, after (1) of Example 3 above, the lid of the vial is removed, the gas aeration treatment similar to (3) of Example 3 above is performed, and a small amount of culture solution is sampled from the vial over time, The concentration of PCE and TCE was analyzed by GC / ECD for headspace gas. In addition, in order to make up for water evaporated during the gas aeration treatment, distilled water was appropriately replenished so that a predetermined amount of water was maintained. The results are shown in FIG.

Discussion of Results First, PCE having a high concentration of 100 mg / L contained in soil could be dechlorinated by anaerobic microorganism treatment for 6 days with anaerobic dechlorinating microorganisms, and could be decomposed to TCE.

  Next, in the case where only the aerobic microbial treatment is carried out following the anaerobic microbial treatment (see Comparative Example 1 and FIG. 2), the concentration of TCE generated by the decomposition of PCE is gradually reduced, but the rate is It was slow. This is considered to be due to the fact that the aerobic microorganism can certainly degrade TCE (see Example 2 above), but the processing capacity of high concentration TCE (about 80 mg / L) is low. From the above, it has been found that efficient treatment of high concentration PCE is difficult by simply combining anaerobic microbial treatment and aerobic microbial treatment.

  In addition, when only the gas aeration treatment was performed following the anaerobic microorganism treatment, the concentration of TCE generated by the anaerobic microorganism treatment rapidly decreased by the gas aeration treatment (see Comparative Example 2 and FIG. 3). However, although the TCE concentration thereafter gradually decreased from 0.1 mg / L to 0.05 mg / L, TCE could not be reduced below the environmental standard value even when the gas aeration treatment was performed until the 14th day. . Therefore, it has been clarified that even if only the gas aeration treatment is performed after the anaerobic microorganism treatment, it is not possible to efficiently treat the high concentration organochlorine compound below the environmental standard value.

  On the other hand, according to the method of the present invention in which at least anaerobic microbial treatment, gas aeration treatment, and aerobic microbial treatment are sequentially performed, PCE is reduced to an environmental standard value or less by 6-day anaerobic microbial treatment, and further generated TCE. Could be decomposed to below the environmental standard value (0.03 mg / L or less) in a total of 10 days. Therefore, according to the method of the present invention, even in soil contaminated with a high concentration of PCE, the pollutant PCE can be efficiently decomposed into TCE, and finally into carbon dioxide and water. It was demonstrated that PCE and TCE can be reduced to environmental standards or less in a short period of time.

It is a figure which shows the density | concentration change of PCE and TCE in the purification method of this invention. It is a figure which shows the density | concentration change of PCE and TCE at the time of giving only an aerobic decomposition | disassembly microbe process to the PCE contaminated soil after the process by the anaerobic dechlorination microbe. It is a figure which shows the density | concentration change of PCE and TCE at the time of giving only a gas aeration process to an anaerobic dechlorination microorganisms process with respect to PCE contaminated soil.

Claims (5)

A method for purifying soil or water contaminated with volatile organochlorine compounds,
A process of treating soil or water under anaerobic conditions with anaerobic dechlorinating microorganisms (hereinafter referred to as "anaerobic microorganism treatment process"),
After the anaerobic microorganism treatment step, the step of aerating gas into the soil or water (hereinafter referred to as “gas aeration step”), and after the gas aeration step, the soil or water is treated with an aerobic decomposition microorganism. A method for purifying contaminated soil or contaminated water, characterized by comprising a step (hereinafter referred to as “aerobic microorganism treatment step”).   The method for purifying contaminated soil or contaminated water according to claim 1, wherein the gas diffused in the gas aeration step is treated by a gas treatment means.   The method for purifying contaminated soil or contaminated water according to claim 1 or 2, wherein a step of aeration of gas into the soil or water is performed before the anaerobic microorganism treatment step.   The method for purifying contaminated soil or contaminated water according to any one of claims 1 to 3, wherein the soil or water is subjected to a step of treating the soil or water with an aerobic decomposing microorganism before the anaerobic microorganism treatment step. Purification method of contaminated water.   The method for purifying contaminated soil or contaminated water according to claim 1 or 2, wherein the anaerobic microorganism treatment step, the gas aeration step, and the aerobic microorganism treatment step are performed at least twice. Purification method.

Images