JP5163235B2 - In-situ purification method for contaminated ground or groundwater - Google Patents

Description

The present invention relates to the original position purification how contaminated soil or contaminated underground water.

  In recent years, techniques for purifying contaminated ground or contaminated groundwater contaminated with organic halogen compounds (for example, volatile organochlorine compounds) in situ have been known. Or the technique which accelerates | stimulates decomposition | disassembly of an organic halogen compound by supplying to contaminated groundwater and activating the anaerobic microorganism which inhabits the contaminated ground or contaminated groundwater is known (refer patent documents 1 and 2). .

  By the way, in such a prior art, in order to advance the start time of decomposition | disassembly of an organic halogen compound, the easily degradable thing (For example, glycerin, molasses etc.) is used as said nutrient (for example). (See Patent Document 3).

  However, since readily degradable nutrients generally have a short life, when readily degradable nutrients are used, the contaminated ground or contaminated groundwater must be purified over a long period of time. In addition, there is a problem that the contaminated ground or the contaminated groundwater cannot be purified over a wide range. In particular, when purifying contaminated ground with poor water permeability in situ, when using easily degradable nutrients (especially those with high adsorptivity to the ground, such as molasses), the nutrients will become contaminated. Since it is difficult to diffuse, the problem that the contaminated ground cannot be purified over a wide range was remarkable. In order to solve such a problem, a large number of injection wells for supplying nutrients to the contaminated ground must be installed, and the cost becomes enormous.

  On the other hand, a long-life nutrient is also known in the prior art (see Patent Document 4), and as such a nutrient, for example, HRC (Hydorogen Release Compound; manufactured by Regensis) and an emulsion of vegetable oil are used. Nutritional materials (EOS; manufactured by EOS) are known.

  However, HRC is not suitable as a nutrient for spreading widely in contaminated ground because of its high viscosity. In addition, the nutritional material in which the vegetable oil is emulsified has a particle size of 1 μm or less and is minute, so it can be diffused into the contaminated ground, but this nutritional material is adsorbable to the ground. It is extremely difficult to diffuse it widely in contaminated ground. Therefore, even when these long-lived nutrients are used, the contaminated ground cannot be purified over a wide range.

That is, in the conventional technology, the start time of the decomposition of the organic halogen compound was advanced, and the contaminated ground or the contaminated groundwater contaminated with the organic halogen compound could not be purified over a long period of time. It is.
JP-A-11-253926 JP 2006-159132 A JP 2006-116420 A JP 2000-135484 A

  The present invention has been made in view of the problems associated with the prior art, and accelerates the start of the decomposition of the organic halogen compound, and the contaminated ground or contaminated groundwater contaminated with the organic halogen compound can be used over a long period and in a wide range. An object of the present invention is to provide an in-situ purification method for contaminated ground or contaminated groundwater that can be purified over a long period of time.

In order to solve the above-mentioned problems, the present invention provides an anaerobic microorganism having an activity of decomposing the organic halogen compound inhabiting the contaminated ground or the contaminated groundwater contaminated with the organic halogen compound. An in-situ purification method for contaminated ground or contaminated groundwater to be activated and purified in situ, wherein at least one of glycerin or sodium gluconate, which is a readily degradable nutrient, and ethanol or isopropyl alcohol Are mixed at a ratio of 50:50 to 10:90, compounded nutrients are blended, and the complex nutrients are supplied to the contaminated ground or the contaminated groundwater to activate the anaerobic microorganisms. And

Furthermore, in situ cleaning method of the present invention, as the readily degradable nutritional material, it is preferable to use a mixture of the sodium gluconate and the glycerin.

  In the present invention described above, the complex nutrient material contains a readily degradable nutrient material, and this easily degradable nutrient material has an action of accelerating the start of the decomposition of the organic halogen compound. Therefore, according to the present invention, it is possible to advance the start of decomposition of the organic halogen compound by the complex nutrient material. In addition, the complex nutrient material contains ethanol or isopropyl alcohol, and these ethanol and isopropyl alcohol function as long-lived nutrient materials (see the following confirmation test), and both are viscous. Since it is low, it has the property of being easily diffused in contaminated ground or contaminated groundwater. Therefore, according to the present invention, it becomes possible to purify contaminated ground or contaminated groundwater contaminated with an organic halogen compound over a long period of time and over a wide range by the complex nutrient material. More specifically, depending on the nature of the contaminated ground or the contaminated groundwater, an easily degradable nutrient material and ethanol or isopropyl alcohol are mixed at a predetermined ratio to formulate an optimal complex nutrient material, and the complex By supplying nutrients to the contaminated ground or the contaminated groundwater and activating the anaerobic microorganisms, it becomes possible to purify the contaminated ground or the contaminated groundwater over a long period of time in the original position. It is.

  The readily degradable nutrient is a nutrient that is easily decomposed in contaminated ground or contaminated ground water and has an action of activating the anaerobic microorganisms, specifically, glycerin or sodium gluconate. At least one of them. Examples of those other than these include sodium lactate.

  ADVANTAGE OF THE INVENTION According to this invention, while starting the decomposition | disassembly start of an organic halogen compound, it also becomes possible to purify the contaminated ground or contaminated groundwater contaminated with the organic halogen compound over a long period of time.

  The present inventors conducted the following confirmation test in order to confirm the action and effect of the complex nutrient material of the present invention. That is, the present inventors use the complex nutritional material of the present invention and three types of nutritional materials (sodium gluconate (100%), glycerin (100%), and ethanol (100%)). The decomposition test of trichlorethylene by the material was performed.

Specifically, the present inventors first, in each 100 ml medium bottle, 150 g of contaminated soil contaminated with trichlorethylene, which is a kind of volatile organochlorine compound, and a nutrient solution containing each nutrient ( About 40 ml of a weight ratio (0.3%) was added. Next, the inventors added trichlorethylene to each medium bottle so that the trichlorethylene concentration was about 5 mg / l. The inventors then measured the trichlorethylene concentration in the head space of each medium bottle. The composition (weight ratio) of each nutrient is shown in Table 1, and the measurement result of the trichlorethylene concentration is shown in FIG.

  As shown in FIG. 1, when only sodium gluconate or only glycerin is used alone as a nutritional material (cases 1 and 2 in Table 1), the trichlorethylene concentration is once in each case. Although it decreased to the environmental standard value (0.02 mg / l) or less, it gradually increased and eventually exceeded the environmental standard value. This means that the nutrients sodium gluconate and glycerin are consumed, and once the degradation of trichlorethylene is promoted, the resolution of trichlorethylene gradually disappears, and the trichlorethylene contained in the contaminated soil gradually elutes. This is presumed to be due to this. In addition, when ethanol alone was used as a nutrient (case 3 in Table 1), the decomposition rate of trichlorethylene was slow, and it took about two months until the trichlorethylene concentration fell below the environmental standard value. . On the other hand, when the complex nutrient of the present invention is used as a nutrient (cases 4 and 5 in Table 1), the trichlorethylene concentration is more promptly compared to the case where only ethanol is used alone. It decreased to below the standard value, and then remained below the environmental standard for about half a year.

Furthermore, in order to confirm the lifetime of the composite nutrient of the present invention, the inventors have determined the relationship between the initial total organic carbon concentration (TOC) of each nutrient and the organic acid concentration after 90 days. I investigated. The results are shown in Table 2. The organic acid is successively decomposed from higher fatty acids having a large number of carbons (butyric acid and isobutyric acid in the case of Table 2) to lower fatty acids having a small number of carbons (acetic acid in the case of Table 2). Therefore, in Table 2, the higher the higher fatty acid having a larger number of carbon atoms, the less the decomposition of the nutrient material.

  As shown in Table 2, when looking at the TOC reduction rate and organic acid composition, the decomposition of each nutritional material was as follows: sodium gluconate (case 1)> glycerin (case 2)> sodium gluconate + glycerin + ethanol (case) 4)> Glycerin + ethanol (Case 5)> Ethanol (Case 3) in that order. Case 4 and Case 5 had the same TOC reduction rate, but Case 5 had a higher proportion of propionic acid than Case 4, so Case 5 was better than Case 4. It is presumed that the decomposition of nutrients has not progressed. From these results, increasing the proportion of sodium gluconate shortens the life of nutrients in the contaminated ground, while increasing the proportion of ethanol increases the life of nutrients in the contaminated ground. I can say that. As described above, an optimal composite nutrient can be blended by mixing sodium gluconate, which is a readily degradable nutrient, and ethanol in a predetermined ratio according to the nature of the contaminated ground.

  In addition, the present inventors have described not only trichlorethylene (TCE) but also other volatile organic chlorine compounds (tetrachloroethylene (TCE), cis-1,2-dichloroethylene (cis-1,2-DCE)). A decomposition test similar to the decomposition test was performed.

Specifically, the present inventors first added 50 g of contaminated soil contaminated with tetrachloroethylene to a 100 ml transparent medium bottle with a septum. Next, in order to adjust the pH, the present inventors added 500 mg (0.3% -soil) of sodium hydrogen carbonate per bottle. Subsequently, the present inventors purely dissolved each nutrient material in advance to adjust the concentration to 0.3%, and added 100 ml of these dissolved solutions to each medium bottle. In addition, since the PCE concentration of the contaminated soil was low, the present inventors added 50 μl of PCE methanol solution (2%) per bottle so that the initial PCE concentration was about 10 mg / l. Then, the present inventors replaced the head space of each medium bottle with nitrogen gas, tumbled the top and bottom of each medium bottle for 1 minute, and then statically cultured in a constant temperature room (25 ° C.) in a dark place. In addition, the inventors will measure the concentration of each volatile organochlorine compound initially, 1 week later, 2 weeks later, 1 month later, 1.5 months later, 2 months later, 3 months later. Thus, it was examined how much the decomposition of each volatile organic chlorine compound was proceeding. The composition of each nutrient material at this time is shown in Table 3, and the measurement results of the concentration of each volatile organic chlorine compound are shown in FIG. 2A to 2D show the measurement results of cases 11 to 14 in Table 3, respectively.

  As shown in FIG. 2, in the case of case 11, that is, when only sodium gluconate (100%) is used alone as a nutrient (see FIG. 2 (a)), the test is started 60 times. After the passage of time, the concentration of cis-1,2-DCE fell below the environmental standard value (0.04 mg / l), but in case 12, that is, only ethanol (100%) was used alone as a nutrient. When used (see FIG. 2 (b)), after 90 days from the start of the test, the concentration of cis-1,2-DCE finally fell below the environmental standard value (0.04 mg / l). It was. This indicates that ethanol has a slower decomposition rate of volatile organochlorine compounds than sodium gluconate. In addition, when comparing the results of Case 13 and Case 14 (see FIG. 2 (c) and FIG. 2 (d)), when a nutrient mixture containing ethanol and sodium gluconate is used as a nutrient, It can be evaluated that the decomposition rate of the volatile organochlorine compound is faster than when only ethanol is used alone. Furthermore, among the results of Case 13 and Case 14, especially, when comparing the amount of cis-1,2-DCE remaining 60 days after the start of the test, the ratio of sodium gluconate to ethanol is large. It is estimated that the decomposition | disassembly rate of a volatile organochlorine compound becomes quick by mix | blending so that it may become.

Next, the present inventors measured the TOC concentration in order to grasp the remaining amount of each nutrient, and from the TOC amount at the start of the test and the TOC amount 60 days after the start of the test, The decomposition rate of nutrients per day was calculated. The results are shown in Table 4.

  As shown in Table 4, in case 11, that is, when sodium gluconate (100%) is used as a nutrient, 53% of the nutrient is degraded 60 days after the start of the test. On the other hand, in the case of case 12, that is, when ethanol (100%) was used as a nutrient, only 8% of the nutrient was decomposed 60 days after the start of the test. . This shows that when only ethanol is used alone as a nutrient, the decomposition rate of the nutrient is slower than when only sodium gluconate is used alone. Moreover, in the case of Case 13, that is, in the case of using a complex nutrient material containing ethanol (50%) and sodium gluconate (50%) as a nutrient material, 60 days after the start of the test, In the case of Case 14, on the other hand, in the case of Case 14, that is, when a composite nutrient containing ethanol (90%) and sodium gluconate (10%) is used as a nutrient, the test is performed. Sixty days after the start, only 14% of the nutrient had degraded. From these facts, when using complex nutrients containing sodium gluconate and ethanol as nutrients, the decomposition rate of volatile organochlorine compounds is slower than when using only sodium gluconate alone It is guessed.

  As described above, when sodium gluconate is used alone as a nutrient, the rate of decomposition of the volatile organic chlorine compound is increased while the rate of consumption of the nutrient is also increased. On the other hand, when only ethanol is used alone as the nutrient material, the consumption rate of the nutrient material is slow, while the decomposition rate of the volatile organochlorine compound is slow. Therefore, by blending sodium gluconate and ethanol, it is possible to increase the decomposition rate of the volatile organochlorine compound, and it is also possible to suppress the consumption rate of nutrients.

  Furthermore, the present inventors considered that there may be a suitable material in addition to ethanol as a component to be blended with an easily degradable nutrient when producing the complex nutrient of the present invention. Therefore, the present inventors performed the following additional tests in order to select such materials.

  In this additional test, the present inventors first added 100 g of silt / clay and 300 ml of each nutrient solution adjusted to a concentration by weight of 0.3% to a 300 ml medium bottle to make a total of 400 g of slurry. did. At that time, the present inventors selected syrup, D-sorbitol, glycerin, isopropyl alcohol, HRC, cyclodextrin, maltitol, ethanol, and sodium gluconate as nutrients to be selected. Next, the present inventors measured the TOC concentration after curing each slurry at 30 degrees. The measurement results are shown in FIG. In FIG. 3, the concentrations of ethanol and isopropyl alcohol are both 98 to 115%, and this value is a value when the concentration on the 0th day of the nutrient is 100%.

  From the results of FIG. 3, it can be said that isopropyl alcohol can be expected to have an effect as a sustained-release nutritional material, like ethanol. From this, the present inventors considered that isopropyl alcohol is suitable in addition to ethanol as a component to be blended with a readily degradable nutrient when preparing the complex nutrient of the present invention. .

It is a graph which shows the result of the decomposition | disassembly test of a trichlorethylene. It is a graph which shows the result of a decomposition | disassembly test of a volatile organochlorine compound. It is a graph which shows the result of a TOC decomposition | disassembly test.

Claims (2)

In order to purify contaminated ground or contaminated groundwater contaminated with organohalogen compounds by activating anaerobic microorganisms that have the activity of decomposing the organohalogen compounds inhabiting the contaminated ground or contaminated groundwater. In-situ purification method of contaminated ground or contaminated groundwater,
At least one of glycerin or sodium gluconate, which is an easily degradable nutrient, and ethanol or isopropyl alcohol are mixed at a ratio of 50:50 to 10:90, and a composite nutrient is blended,
An in-situ purification method for contaminated ground or contaminated groundwater, wherein the complex nutrient is supplied to the contaminated ground or the contaminated groundwater to activate the anaerobic microorganisms.   The contaminated ground or contaminated groundwater purification method according to claim 1, wherein a mixture of the glycerin and the sodium gluconate is used as the easily degradable nutrient.

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