JP5866508B1 - Microbial composition - Google Patents

Abstract

The composition for microorganisms may be left in the field together with the transport container after being transported to the soil purification site, but when left for several weeks, a phenomenon of crystallization occurs in the transport container. A composition for microorganisms capable of purifying organochlorine compounds in soil and groundwater, one or more sugar alcohols selected from sorbitol, mannitol, and xylitol, glycerin, a nonionic surfactant, The composition for microorganisms, which is composed of water and the sugar alcohol content is less than 6 times that of the glycerin, is crystallized in the container even when left in the field with the transport container. Absent.

Description

  The present invention relates to a composition for microorganisms that is injected into soil and groundwater in order to decompose organochlorine compounds in soil and groundwater using microorganisms and purify the soil and groundwater.

  Soil and groundwater contaminated with chemical substances is a problem that breaks the balance of not only human beings but also the entire biological world, and some measures are necessary from the viewpoint of environmental protection. In addition, leaving contaminated soil and groundwater will limit the area of human activity, and measures are also needed from an economic point of view.

  Conventionally, various methods such as a lime method, an iron powder method, a soil excavation and replacement method, a soil moisture cleaning method, and a bioremediation method have been proposed to purify soil and groundwater contaminated with chemical substances. Soil and groundwater contamination is often widespread and methods such as replacing the soil itself are enormous in scale and cost.

  Bioremediation is said to be suitable as one of the methods for economically purifying soil and groundwater in situ without requiring large-scale construction. This is a method of decomposing chemical substances that are pollutants into aerobic or anaerobic microorganisms in soil and groundwater.

  For example, Clostridium microorganisms decompose organic substances into acetic acid and the like in an anaerobic atmosphere. Hydrogen is released during the process. This hydrogen can be replaced with chlorine of organic chlorine compounds such as chloroform, dichloromethane, dichloroethane, and trichloroethylene to purify these chemical substances. In other words, an organic chlorine compound can be dechlorinated and a chemical substance can be purified by a reduction reaction with hydrogen generated in an anaerobic atmosphere.

  A group of substances that generate and provide hydrogen as described above is called a hydrogen donor, and while activating microorganisms, a group of substances that become hydrogen donors (hereinafter referred to as “nutrient sources”) are put into soil and groundwater. Injecting methods have been proposed. When such a nutrient source is excessively injected, there is a concern of secondary contamination due to diffusion to a portion other than the contaminated portion. Therefore, for example, Patent Document 1 discloses a composition in which a linear fatty acid granulated or a linear fatty acid is mixed in glycerine so that it is difficult to move from the injection point.

  However, it has been found that microorganisms are inactivated under high-concentration nutrient sources, and extremely diluted nutrient sources are sent to soil and groundwater. Moreover, if the nutrient source is close to natural products, there is little toxicity and there is little need to worry about secondary contamination. Then, rather than solids or gels that do not move from the buried site, a method has been proposed in which the viscosity is rather low, and the nutrient source can be provided widely from one well by diffusing in soil and groundwater.

  Patent Document 2 discloses a technique in which a nutrient source mainly composed of sorbitol is diluted to 2000 ppm and is fed into soil and groundwater to decompose microorganisms into organochlorine compounds. More specifically, 60% sorbitol, 10% glycerin, 2% anions, and 28% water diluted to 2000 ppm are fed into soil and groundwater for diffusion. At the end of diffusion, the concentration of carbon in the nutrient source is diluted to approximately 100 ppm, so that the microorganism is at a concentration that allows co-uptake with chemicals. For this reason, decomposition of the chemical substance is promoted.

  Patent Document 3 discloses one in which a nonionic surfactant is added so that a diluted nutrient source can be diffused well in the ground. Here, the nutrient source includes a polyhydric alcohol and a surfactant, and the polyhydric alcohol is one or more sugar alcohols selected from sorbitol, mannitol, and xylitol, 62 to 68 parts by weight, and 8 to 10 parts by weight. The surfactant is 1 to 5 parts by weight of a nonionic surfactant, and further comprises 22 to 25 parts by weight of water.

JP 2002-370085 A (Patent No. 3746726) JP 2009-11939 A (Patent No. 5023850) Patent No. 5,587,453

  The nutrient source (composition for microorganisms) having the composition of Patent Document 3 is actually used and gives the expected effect. Such a nutrient source is prepared in advance in a factory, and packed in an 18-liter can (so-called “Ito can”: hereinafter referred to as “carrying container”) and carried to the site. Since soil purification requires weeks or months, transport containers containing nutrients are often left outdoors.

  Then, the problem that the nutrient source hardened in the transport container and it was difficult to take out from the transport container occurred.

  The present invention has been conceived in view of the above problems, and provides a composition for microorganisms (nutrient source) that does not coagulate in a transport container even when left in the field.

More specifically, the composition for microorganisms according to the present invention comprises:
A composition for microorganisms capable of purifying organochlorine compounds in soil and groundwater,
One or more sugar alcohols selected from sorbitol and mannitol;
Glycerin,
A nonionic surfactant;
Composed of water,
The sugar alcohol, Ri less content der than 6 times the glycerin,
It said sugar alcohol is an der Rukoto wherein said less 58 mass% in the composition for 53 mass% or more microorganisms.

  The composition for microorganisms according to the present invention does not coagulate in the transport container even when repeatedly subjected to heat shock. Therefore, even after being transported to the site, it does not take time to manage until it is used.

  The composition for microorganisms according to the present invention will be described below. The following description exemplifies a part of the embodiments and examples of the present invention, and the present invention is not limited to the following description. The following embodiments can be modified without departing from the gist of the present invention.

  The composition for microorganisms according to the present invention contains a material for activating microorganisms in soil and groundwater, and is intended to diffuse from the injection site. Therefore, it is a liquid and has a low viscosity. Moreover, since it aims at using it in the highly diluted state with respect to the microorganisms in soil and groundwater, it needs to be water-soluble. It must function as a nutrient source for the purpose of purifying soil and groundwater.

  As such a material, sorbitol, a sugar alcohol which is a polyhydric alcohol, can be suitably used. However, mannitol can be used similarly. Here we describe sorbitol.

  A humectant is mixed to keep the sorbitol diluted with water in the soil and groundwater. As the humectant, glycerin, which is a trivalent alcohol, can be suitably used. This is because glycerin itself can be a nutrient source for microorganisms. Further, like ethylene glycol, the freezing point can be lowered, so that it also serves as an antifreeze. This is useful when purifying soil and groundwater in places with low temperatures.

  Further, in order not to coagulate even when stored in the field, glycerin is contained in the microbial composition before dilution at a ratio of 1/6 or more with respect to sorbitol. As will be shown in the following examples, sorbitol, which is a polyhydric alcohol, may be seeded in the transport container when it is left at a high concentration of 60% by mass or more, due to a change in ambient temperature. In some cases, crystallization occurs around the seed crystal and solidifies.

  However, this phenomenon can be avoided by reducing the concentration or increasing the glycerin content. Therefore, in addition to the mixing ratio of sorbitol and glycerin, it is preferable to adjust the content of sorbitol to 53 mass% or more and 58 mass% or less.

  The composition for microorganisms according to the present invention may contain water at a ratio of about 40% by mass or less. Basically, water is not necessary as a nutrient source. However, it is also necessary to adjust the concentration of nutrient sources. Water may be the remainder of sorbitol, glycerin and other additives.

  Moreover, it is preferable that the water to be used has been subjected to a sterilization treatment. Water contains bacteria such as water mold. This is because sorbitol can also be a nutrient source for these microorganisms, and therefore, if miscellaneous bacteria are included, the problem arises that the composition for microorganisms corrodes during storage.

  The sterilization process may be a boiling process or may be irradiated with ultraviolet rays. Moreover, you may use the water which does not contain a germ in the first place, such as a pure water and an ultrapure water.

  The nutrient source includes a nonionic surfactant. The surfactant lowers the surface energy of the soil when the nutrient source is injected into the soil and groundwater, and makes the soil easy to get wet with the nutrient source. As a result, along with the effect of capillarity, it makes it easier for nutrients to diffuse in soil and groundwater. Nonionic surfactants can exhibit surface activity regardless of the pH of the liquid.

  Thus, nonionic surfactants are independent of the pH in soil and groundwater. In soil and groundwater, an anaerobic environment can be easily obtained, so that anaerobic decomposition of organic matter proceeds and the soil tends to become acidic. Even in such an environment, the composition for microorganisms can be diffused if it is a nonionic surfactant.

  Nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene higher alcohol ether, polyoxyethylene Myristyl ether, polyoxyethylene distyrenated phenyl ether, etc. are sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan distearate, etc., which are sorbitan fatty acid esters, polyoxyethylene sorbitan Polyoxyethylene sorbitan mono-coconut fatty acid ester, polyoxyethylene sorbitan laurate, polyoxy Ethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan triisostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbite tetraoleate, etc. can be used . Among these, polyoxyethylene lauryl ether can be preferably used.

  Furthermore, the composition for microorganisms according to the present invention may further contain a pH buffer. The pH buffer can be added from 1 to 4 parts by weight based on the total amount. When adding the pH buffering agent, the ratio with other components is appropriately adjusted.

  Examples of pH buffers that can be suitably used include lactic acid buffers, citrate buffers, phosphate buffers, and acetate buffers. These are added from 1 to 4 parts by weight.

  The reason for using the pH buffer is as follows. By injecting the composition for microorganisms as a nutrient source into soil and groundwater, the microorganisms in the soil and groundwater can be activated. However, when anaerobic decomposition proceeds by activated microorganisms, an organic acid such as acetic acid is generated, and the pH in the soil and groundwater decreases. If the pH of the soil and groundwater is too low, the activity of microorganisms will be suppressed. That is, when the composition for microorganisms is injected into soil and groundwater, a period during which decomposition of the organic chlorine compound or the like does not proceed is formed for a certain period after injection. This is called the “purification stagnation period”.

  The pH buffer agent can alleviate the decrease in pH due to the production of an organic acid such as acetic acid to some extent, and can suppress the “stagnation period of purification” due to the excessive decrease in pH. Therefore, there is no “purification stagnation period”. As a result, there is an advantage that the period required for purification of soil and groundwater is shortened.

  Examples of the composition for microorganisms according to the present invention are shown below. For confirmation of crystallization, each sample shown in Table 1 was prepared, and 5 cans were packed in a transport container, and a temperature change was given in a constant temperature test chamber. The carrying container is an ordinary 18 liter can and is made of iron. No treatment such as providing a protective film or a protective sheet on the inner wall is performed. In a constant temperature test chamber, heat shock was applied for 30 days at a cycle of 24 ° C. for 12 hours and 15 ° C. for 12 hours. In the thermostat, it takes about 60 minutes to change the temperature.

  Sample 1 is 65% by mass of sorbitol, 10% by mass of glycerin, 2% by mass of nonionic surfactant, and 23% by mass of water. As the nonionic surfactant, polyoxyethylene lauryl ether was used. Moreover, the boiled tap water was used for water. This is the same for all subsequent samples. In Sample 1, crystallization occurred in 5 out of 5 cans. The results are shown in Table 1.

  Sample 2 is 60% by mass of sorbitol, 10% by mass of glycerin, 2% by mass of nonionic surfactant, and 28% by mass of water. In Sample 2, crystallization occurred in 5 out of 5 cans. The results are shown in Table 1.

  Sample 3 is 59% by mass of sorbitol, 10% by mass of glycerin, 2% by mass of nonionic surfactant, and 29% by mass of water. Sample 5 did not crystallize in all 5 cans. The results are shown in Table 1.

  Sample 4 is 58% by mass of sorbitol, 10% by mass of glycerin, 2% by mass of nonionic surfactant, and 30% by mass of water. Sample 5 did not crystallize in all 5 cans. The results are shown in Table 1.

  Sample 5 is 55% by mass of sorbitol, 10% by mass of glycerin, 2% by mass of nonionic surfactant, and 33% by mass of water. The results are shown in Table 1. Sample 5 did not crystallize in all 5 cans. The results are shown in Table 1.

  Referring to Table 1, when sorbitol exceeded 59 mass%, crystallization occurred in more than half of 5 cans of each sample. However, at 58% by mass, no crystallization occurred in 5 cans. As is well known, sorbitol crystals can be obtained by cooling to a very low temperature and slowly raising the temperature. However, such temperature treatment is not performed here.

  Therefore, it is unlikely that pure sorbitol crystals were generated and became crystal seeds. Probably, the minute impurities mixed in during the preparation formed a pseudo seed crystal at the boundary between the wall surface in the transport container and the liquid surface of the microbial composition, and it was thought that crystallization occurred due to this. . Here, the phenomenon that the composition for microorganisms packed in the transport container is solidified is called crystallization.

  Next, the glycerin content was changed with respect to 60% by mass of sorbitol causing crystallization and 58% by mass not causing crystallization. The composition of each sample is shown in Table 2.

  Sample 6 is 60% by mass of sorbitol, 7% by mass of glycerin, 2% by mass of nonionic surfactant, and 31% by mass of water.

  Sample 7 is 58% by mass of sorbitol, 7% by mass of glycerin, 2% by mass of nonionic surfactant, and 33% by mass of water.

  Sample 8 is 60% by mass of sorbitol, 8% by mass of glycerin, 2% by mass of nonionic surfactant, and 30% by mass of water.

  Sample 9 is 58% by mass of sorbitol, 8% by mass of glycerin, 2% by mass of nonionic surfactant, and 32% by mass of water.

  Sample 10 is 60% by mass of sorbitol, 9% by mass of glycerin, 2% by mass of nonionic surfactant, and 29% by mass of water.

  Sample 11 is 58% by mass of sorbitol, 9% by mass of glycerin, 2% by mass of nonionic surfactant, and 31% by mass of water.

  Sample 12 is 60% by mass of sorbitol, 11% by mass of glycerin, 2% by mass of nonionic surfactant, and 27% by mass of water.

  Sample 13 is 58% by mass of sorbitol, 11% by mass of glycerin, 2% by mass of nonionic surfactant, and 29% by mass of water.

  Sample 14 is 60% by mass of sorbitol, 12% by mass of glycerin, 2% by mass of nonionic surfactant, and 26% by mass of water.

  Sample 15 is 58% by mass of sorbitol, 12% by mass of glycerin, 2% by mass of nonionic surfactant, and 28% by mass of water.

Sample 16 is 65% by mass of sorbitol, 11% by mass of glycerin, 2% by mass of nonionic surfactant, and 22% by mass of water. The results are shown in Table 2.

  Referring to Table 2, even in Samples 12 and 14 (60% by mass of sorbitol) that were supposed to be crystallized from the results in Table 1, no crystallization occurred in 5 out of 5 cans. In addition, crystallization occurred in one or two of the five cans of Samples 7, 9, and 11 (58% by mass of sorbitol) that were supposed to be free from crystallization. In addition, even a transport container judged that crystallization did not occur, a large lump was formed inside.

  From the above results, it was concluded that the presence or absence of crystallization was not only the concentration of sorbitol. Next, attention was paid to the ratio of sorbitol and glycerin. Table 2 shows the ratio of sorbitol to glycerin (shown as “S: G”).

  When the ratio of sorbitol to glycerin was compared, it could be expected that crystallization occurred at 6: 1. Therefore, Sample 16 was the one shown in Table 1 (65% by mass of sorbitol), and a composition containing 11% by mass of glycerin was tested. In sample 16, sorbitol to glycerin is 5.9 to 1. As shown in Table 2, even if sample 16 had a sorbitol content of 65% by mass, crystallization did not occur in 5 of 5 cans as long as the ratio was 6 times or less of glycerin.

  As described above, it was found that crystallization can be avoided if the ratio of sorbitol and glycerin is smaller than 6: 1 in the composition for microorganisms (if the amount of sorbitol is small).

  Since sorbitol and mannitol are very similar in structure, the same phenomenon occurs with mannitol. Based on the knowledge obtained in the above experiment for sorbitol, an experiment was conducted on the presence or absence of crystallization with the composition shown in Table 3.

  Sample 17 is mannitol 60 mass%, glycerin 7 mass%, nonionic surfactant 2 mass%, and water 31 mass%. The ratio of mannitol to glycerin (represented as “M: G” in Table 3) is 8.5: 1.

  Sample 18 is 58% by mass of mannitol, 9% by mass of glycerin, 2% by mass of nonionic surfactant, and 31% by mass of water. The ratio of mannitol to glycerin (represented as “M: G” in Table 3) is 6.4: 1.

  Sample 19 is 60% by mass of mannitol, 11% by mass of glycerin, 2% by mass of nonionic surfactant, and 27% by mass of water. The ratio of mannitol to glycerin (represented as “M: G” in Table 3) is 5.4: 1.

  Sample 20 is 58% by mass of mannitol, 11% by mass of glycerin, 2% by mass of nonionic surfactant, and 29% by mass of water. The ratio of mannitol to glycerin (represented as “M: G” in Table 3) is 5.3: 1.

  Sample 21 is mannitol 65 mass%, glycerin 11 mass%, nonionic surfactant 2 mass%, and water 22 mass%. The ratio of mannitol to glycerin (represented as “M: G” in Table 3) is 5.9: 1.

  The results are shown in Table 3. Referring to Table 3, when the ratio of mannitol to glycerin was smaller than 6: 1 (low mannitol or high glycerin), no crystallization occurred. In Sample 18, crystallization occurred in 4 out of 5 cans. This is the same composition ratio as that of sample 11 in the case of sorbitol. In the case of sorbitol, crystallization was observed in 1 out of 5 cans. Therefore, it can be said that mannitol is more easily crystallized than sorbitol.

  Next, the Example which confirms the soil purification effect of the composition for microorganisms which concerns on this invention is shown. The example was performed at a site contaminated with tetrachlorethylene. The aquifer was 2.0 to 12.2 m from the ground surface. Moreover, the tetrachlorethylene density | concentration in groundwater was about 0.8 mg / L. In the test, an injection well having a diameter of 100 mm was installed, and a pipe was connected to the well opening to inject the composition for microorganisms.

  In addition, an observation well was provided at a location 3 m away from the injection well, and the tetrachlorethylene concentration, sorbitol concentration, and pH in the groundwater were regularly monitored. In addition, the injection well and the observation well into which each microbial composition was injected were provided sufficiently apart from each other so as not to be affected by the microbial composition.

  For each microorganism composition to be injected, an aqueous solution diluted to 2000 ppm was used, and after continuous injection at 9.0 L / min for 7 days, only monitoring was continued.

  In Example 1, 52% by mass of sorbitol, 9% by mass of glycerin, 2% by mass of a nonionic surfactant, and 37% by mass of water are mixed. The ratio of sorbitol and glycerin is “5.7: 1”. In addition, polyoxyethylene lauryl ether was used as the nonionic surfactant. As the water, water obtained by boiling normal tap water for 10 minutes and cooling it to 25 ° C was used. The composition and results are shown in Table 4.

  In Table 4, “G ratio” means “ratio of glycerin” and indicates the ratio of sugar alcohol when glycerin is 1. In Table 4, “S” represents sorbitol, and “M” represents mannitol.

  In Example 2, 55% by mass of sorbitol, 10% by mass of glycerin, 2% by mass of nonionic surfactant, and 33% by mass of water are mixed. The ratio of sorbitol and glycerin is “5.5: 1”. In Example 3, 58% by mass of sorbitol, 10% by mass of glycerin, 2% by mass of nonionic surfactant, and 30% by mass of water are mixed. The ratio of sorbitol and glycerin is “5.8: 1”.

  In Example 4, 52% by mass of mannitol, 9% by mass of glycerin, 2% by mass of nonionic surfactant, and 37% by mass of water are mixed. The ratio of mannitol to glycerin is “5.7: 1”.

  In Example 5, 55% by mass of mannitol, 10% by mass of glycerin, 2% by mass of nonionic surfactant, and 33% by mass of water are mixed. The ratio of mannitol to glycerin is “5.5: 1”. In Example 6, 58% by mass of mannitol, 10% by mass of glycerin, 2% by mass of nonionic surfactant, and 30% by mass of water are mixed. The ratio of mannitol to glycerin is “5.8: 1”.

  In all the microbial compositions of Examples, the ratio of sugar alcohol to glycerin is 6: 1 or less (low sugar alcohol). The composition and results are shown in Table 4. When carrying out this example, the microbial composition filled in the transport container had been left in the field at the test site for more than one month, but none of the ones that had crystallized had been allowed to stand. .

  With reference to Table 4, the decomposition rate was calculated | required from the density | concentration of the tetrachlorethylene before a test, and the density | concentration after 30 days, and was displayed by%. Moreover, the sugar concentration (mg / L) after 7 days at a sampling point 3 m away from the well was shown.

  In all of Examples 1 to 6, tetrachlorethylene at a point 3 m away from the well was decomposed by 95% or more. In addition, the sugar concentration after 7 days at a sampling point 3 m away from the well exceeded 800 mg / L. From this, it is understood that even the composition of the microorganism composition according to the present invention improves the wettability of the soil surface in a highly diluted state and contributes to the decomposition of tetrachlorethylene while spreading in the ground. It was.

  The composition for microorganisms according to the present invention can be suitably used as a nutrient source for decomposing and purifying organochlorine compounds in soil and groundwater using microorganisms in soil and groundwater.

Claims (2)

A composition for microorganisms capable of purifying organochlorine compounds in soil and groundwater,
One or more sugar alcohols selected from sorbitol and mannitol;
Glycerin,
A nonionic surfactant;
Composed of water,
The sugar alcohol, Ri less content der than 6 times the glycerin,
It said sugar alcohol is microbial composition characterized 58 mass% der Rukoto least 53 wt% in the microbial composition.   The composition for microorganisms according to claim 1, wherein the nonionic surfactant is polyoxyethylene lauryl ether.