JP2003053319A - Polluted soil cleaning agent and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polluted soil cleaning agent and polluted soil cleaning method of exceedingly improving the biological activity of the microorganisms dormant in the polluted soil by inexpensive and safe additives. SOLUTION: The cleaning of the polluted soil is realized by mixing rice bran with the polluted soil and promoting the propagation and growth of the microorganisms in the soil and improving the biological activity. The additives prepared by adding microorganism sources, such as brunizem and compost, to the rice bran or the additives formed by adding nutrients like inorganic nutrient salts, such as nitrogen and phosphorus, to the rice bran are capable of further efficiently cleaning the polluted soil as synergistic effects act thereon.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a contaminated soil remediation agent and method utilizing microorganisms.

[0002]

2. Description of the Related Art It is well known that various microorganisms that decompose various substances including harmful substances are present in the natural world and that the self-cleaning action of the natural world is formed. In recent years, biodegradation technology that decomposes pollutants in contaminated soil using such microorganisms has been drawing attention. Some of these microorganisms are known to decompose specific harmful substances, but since there are innumerable microorganisms in nature, the microorganisms directly involved in the decomposition have been identified. Often not. On the other hand, contaminated soil also varies in the degree of pollution and the type and number of pollutants. In the conventional bioremediation of contaminated soil, the method of adding indigenous or foreign microorganisms with nutrients such as inorganic nutrient salts (bioaugmentation) and land farming, biopile, biosparging, etc. , There is a method of adding nutrients such as inorganic salts, oxygen, and other organic substances to contaminated soil to activate microorganisms in the soil (biostimulation).

[0003]

However, these methods have a problem that the added microorganisms and nutrients are expensive. In addition, there is also a problem that the microorganisms and nutrients are not so effective in many cases depending on the target contaminated soil. The present invention has been made in view of such a problem, and by using an inexpensive and safe additive, a contaminated soil purifying agent and a contaminated soil purifying method that markedly improve the biological activity of microorganisms latent in contaminated soil. The purpose is to provide.

[0004]

In order to solve the above problems, the invention according to claim 1 uses a polluted soil purifying agent using rice bran. According to such a polluted soil purifying agent, the added rice bran can dramatically improve the biological activity of microorganisms in the polluted soil.

In the invention described in claim 2, rice bran is added to the microbial source aged by the natural fermentation process.
The contaminated soil purifying agent described in 1. is used. Such a contaminated soil purifier is a rice bran that improves the biological activity of the microorganisms contained in the microbial source, so it becomes a contaminated soil purifier with a high biological activity in advance, and the microorganisms that decompose pollutants into contaminated soil are not so much. Rapidly grows microorganisms even when not present.

Here, the source of microorganisms aged by the natural fermentation process means that the microorganisms propagate through natural fermentation regardless of whether humans are involved in promoting fermentation, and their decomposition products and secretions produce eutrophication. It is a growth medium of a group of microorganisms that have been activated and in which the activities of various microorganisms existing in nature have become active.

The invention according to claim 3 uses the polluted soil purifying agent according to claim 1, wherein rice bran is added to a nutrient consisting of nutrients for improving the biological activity of microorganisms in the polluted soil. Such a contaminated soil purifying agent can exert a more excellent biological activity improving effect by combining the biological activity improving effect of rice bran and the biological activity improving effect of such a nutrient.

Here, the nutrients for improving the biological activity are elements contained in essential elements essential for biological activity, and they are formed into inorganic salts in a form that is easily ingested by microorganisms, for example, nitrogen. A combination of elements such as phosphorus, potassium and the like in an appropriate ratio is generally called a nutritional supplement.

In the invention according to claim 4, the microbial source aged in the natural fermentation process is black soil or compost, and the contaminated soil purifying agent according to claim 2 is used. Here, the black soil is soil that is rich in organic matter due to the mixture of volcanic ash soil and other plant materials that have rotted over the years, and is known as compost.
Is a mixture of fallen leaves, straw, food waste, and the like, which is naturally fermented and ripened. All of them contain a lot of natural microorganisms capable of decomposing various substances together with their nutrient-rich organic substances. Therefore, even when the number of microorganisms present in the contaminated soil is small, the effect of improving the biological activity of rice bran can be effectively utilized. Also, if the soil contains a large amount of microorganisms, these soils can be used instead of the black soil.

According to the invention of claim 5, in the contaminated soil,
Rice bran is added and mixed to use a polluted soil remediation method that improves biological activity. According to this method, when rice bran is mixed with the contaminated soil, it serves as a nutrient source for the microorganisms latent in the contaminated soil, and the biological activity of the microorganisms can be enhanced.

The invention according to claim 6 uses the method for purifying contaminated soil according to claim 5, wherein a microorganism source aged by a natural fermentation process is added together with rice bran. According to this method, both the microbial source and the rice bran as its nutritional source are mixed in the contaminated soil, so that the microorganisms can be more efficiently propagated and grown in the contaminated soil and the biological activity can be enhanced.

The invention according to claim 6 uses the method for purifying contaminated soil according to claim 5, wherein a nutrient agent comprising a nutrient for improving the biological activity of microorganisms in the contaminated soil is added together with the rice bran. According to this method, the effect of improving the biological activity of rice bran and the effect of improving the biological activity of such nutrients can be synergized to exert a more excellent effect of increasing the biological activity.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, referring to the accompanying drawings,
An embodiment of the present invention will be described. In the contaminated soil purifying agent according to the present invention, rice bran is used as an inexpensive and safe additive. Rice bran alone has an effect as a pollutant for soil purification, but in order to make it more effective, in the second embodiment, it is used by mixing with a microbial source aged by a natural fermentation process such as black soil or compost. . Further, in the third embodiment, it is used as a mixture with a nutrient containing inorganic nutrient salts such as nitrogen, phosphorus and potassium.

First, the rice bran will be briefly described. Rice bran is a powder of seed coat and germ that can be obtained when whitening brown rice. Since it is rich in oil content, it is also used for the purpose of obtaining edible bran oil by pressing. The bran oil contains a lipase hydrolase lipase. Protein, vitamin B1
It is rich in nutrients such as and is used for foods such as bran pickles, and is also often used as livestock feed. Therefore, it is safe for the natural environment and the human body as a nutritious quasi-food. In addition, it is a very cheap product because it is a waste product of the polished white rice. Note that rice bran is sometimes called Kobrun or Bran, but they are the same.

The present inventor has paid attention to the above-mentioned characteristics of rice bran, studied the biological activity of the rice bran, and obtained the interesting experimental results to arrive at the present invention. That is, it was found that mixing rice bran with contaminated soil improves the biological activity. further,
It was also found that when mixed with black soil, compost, and inorganic nutrients such as nitrogen / phosphorus, the biological activity was remarkably improved as compared with the case where they were mixed alone.

Below, the experimental results that support them will be explained. First, the experimental method will be described. The soil used in the experiment is the soil of three types of contaminated sites that are actually contaminated with heavy oil A (hereinafter referred to as contaminated soil X, contaminated soil Y, and contaminated soil Z). The additives used as contaminated soil cleaning agents and their usage ratios are as follows.
On the street. (Hereinafter, each additive may be referred to by a number.) The percentages mean weight percentages unless otherwise specified.

(1) Rice bran: 0.1% relative to contaminated soil
Was added. (2) Nitrogen and phosphorus: The amount of contaminated oil was measured, and nitrogen and phosphorus were adjusted and added so as to be 10% and 1% of the oil respectively. (3) Compost: 10% of contaminated soil
Was added. (4) Decomposing bacterium A: It is commercially available for contaminated soil, and was added according to the designated conditions. (5) B-degrading bacterium: It is commercially available for contaminated soil, and was added according to the specified conditions. (6) Black soil: 10% was added to the contaminated soil.

In the experiment, the contaminated soil and the above additives were mixed to prepare a sample, which was placed in a closed bottle, and the gas phase was replaced with oxygen gas and closed. Then, it was incubated at 30 ° C., and the change in oxygen content over time was measured.

Although no particular data is shown here,
Preliminary experiments have confirmed that there is a correlation between the amount of oxygen consumed and the amount of oil decomposed in soil. Therefore, an increase in oxygen consumption is a manifestation of activation of reproduction and growth of microbial groups in soil, which means an increase in biological activity for the general decomposition of nutrients. The biological activity of oil-degrading microorganisms, which are ubiquitous in soil, can be seen to increase as well.

FIG. 1 shows the results of experiments in which rice bran (1), nitrogen and phosphorus (2) were added to the contaminated soil X as additives and the difference in their effects was tested. The vertical axis represents the oxygen consumption amount obtained by measuring the oxygen reduction amount in the closed bottle as the number of oxygen molecules per 1 g of contaminated soil in μmol. The horizontal axis represents the elapsed time and is shown in units of days. The measurement is 5, 10,
It was performed when 16, 23, 38 and 63 days had passed.

The polygonal lines in the figure show the results of different samples. Line 1 is the contaminated soil X itself without additives, line 2 is (2) added, line 3 is (1) added, line 4 is (1) +
The results obtained by adding (2) are shown below. In addition, in order to make the graph easier to understand, in the figure, those with (1) added are rice bran +, and those with (2) are N / P.
I have entered +. Those not added are indicated as rice bran- and N / P-, respectively.

The changes in the graph show very similar changes in polygonal line 1 and polygonal line 2 representing the measured values of the sample containing no rice bran (1), and until the 16th day, it was almost linear. The oxygen consumption increased, and then the change became gradual, and after the 23rd day, the slope became more gradual, showing a substantially linear change.

The polygonal lines 3 and 4 representing the measured values of the sample containing rice bran (1) also follow a similar process, showing a steep rise in the initial stage, and a gradual change until the 23rd day. Is gradually increased, and thereafter, it increases substantially linearly with a gentler inclination. The inclination after 23 days is slightly larger than the polygonal lines 1 and 2. Compared with the results on the 63rd day, the lowest oxygen consumption is in the case of the contaminated soil X itself, whereas (1) +
(2) shows 1.53 times, (1) shows 1.47 times, and (2) shows 1.04 times.

Here, the polygonal line 1 of only the contaminated soil shows the same tendency change as the other polygonal lines. This means that microorganisms are latent in the contaminated soil, and their breeding is progressing by supplying oxygen and maintaining heat.

On the other hand, since the additive does not contain any new microorganisms, the reason that all the other polygonal lines exceed polygonal line 1 is that the addition of the additive causes the organisms of the microorganisms that are latent in the contaminated soil. It can be considered that the activity is improved. However, the rate of improvement was different depending on the type of each additive. According to the above results, rice bran (1) was excellent, but nitrogen and phosphorus (2) were not so effective.

However, since the value of polygonal line 4 is slightly larger than the value of polygonal line 3 plus the value of polygonal line 2, by adding (1) to (2), only (1) is obtained. It can be seen that, of course, the effect is slightly superior to the simple sum of the respective effects and has a slight synergistic effect.

From the above, it has been found that the rice bran (1) has an excellent biological activity improving action as compared with nitrogen and phosphorus (2) which are widely used as nutrients for inorganic nutrients of microorganisms. It was also found that the combined use of the two exerts a synergistically excellent effect, albeit slightly.

From the above results, it can be seen that rice bran has a role of improving the biological activity of microorganisms latent in the contaminated soil.

Next, the experimental results shown in FIG. 2 will be described.
FIG. 2 is an experiment in which the results obtained by adding other additives to the contaminated soil X were examined in the same manner as described above, and particularly the characteristics depending on the presence or absence of rice bran (1) were noted. The vertical axis and the horizontal axis of the graph are the same as in the case of FIG.

Lines 5, 6 and 7 show the results when the additives (3), (4) and (5) were added, respectively, and the rice bran (1) was not added. Lines 8, 9 and 10 are
The results obtained by adding (1) to the additives (3), (4), and (5) are shown.

Although there is a tendency that the change of any of the polygonal lines is slightly large on the 63rd day, there is no big difference from the case of FIG. 1, and after the oxygen consumption sharply increases in the initial stage,
Gradually slowing down, it is changing to a gradual linear change.

Comparing the results on the 63rd day, the samples with excellent biological activity were the ones to which rice bran (1) was added together. From the larger one, compost (3), A degrading bacteria (4) ) And B-degrading bacteria (5). Further, compared with FIG. 1, since the polygonal line 5 representing the result of the sample containing only the contaminated soil X added with (5) is almost equal to the polygonal line 1, (5)
It can be seen that the effect itself is almost nonexistent.

Comparing the effects of rice bran (1) with the results on day 63, (3), (4) and (5) were about 1.2 and 1 respectively as compared with the case without rice bran (1). .4, 1.5
The oxygen consumption is doubled, and it can be seen that the biological activity is improved at a remarkable rate as the one showing less biological activity by itself.

Regarding the B-degrading bacterium (5), the broken line 8 ((5) + (1)) is replaced by the broken line 3 (only (1)) in FIG.
Compared with, the value of line 8 is the same as line 3 at any time.
Considering that (5) alone was not different from the result of the contaminated soil X alone (line 5), the reason that line 8 exceeds line 3 is due to the synergistic effect with rice bran (1). Conceivable.

From the above, rice bran (1) is a source of other microorganisms,
It was found that even when used in combination with nutritional supplements, their synergistic effects led to significant improvements in biological activity.

Next, the experimental results shown in FIGS. 3 and 4 will be described. FIG. 3 shows the same as above in the contaminated soil Y,
The results when black soil (6) and rice bran (1) were added as additives are shown. The vertical axis and the horizontal axis of the graph are the same as in the case of FIG. However, the scale of the vertical axis is different. Black soil + and rice bran + in the figure have black soil (6) and rice bran (1) added, respectively. Black soil − and rice bran − do not have black soil (6) and rice bran (1) added, respectively. It means that.

The polygonal line 11 is only for the contaminated soil Y, the polygonal line 12 is (6), and the polygonal line 13 is (6).
And (1) are added together.

The changes in all of the polygonal lines are almost the same, and they rise steeply in the initial stage, thereafter the changes are gradual, and after the 15th day, they change in a substantially straight line with that inclination.

Comparing the results on the 63rd day, the case where only black soil (6) was added was about 1.2 times that of the contaminated soil alone, whereas the black soil (6) and rice bran (1) were added. If
It is about 1.5 times.

FIG. 4 shows the result of conducting the same experiment as in FIG. 3 on the contaminated soil Z. The polygonal line 14 is the case of only the contaminated soil Y, and the polygonal line 15 is the case of adding (6),
The polygonal line 16 shows the case where both (6) and (1) are added.

The change in any of the polygonal lines is almost the same, 2
Up to the third day, it increased slightly up and down and then increased linearly with a gradual slope.

Comparing the results on the 63rd day, the case where only the black soil (6) was added was about 1.5 times that of the contaminated soil alone, whereas the black soil (6) and the rice bran (1) were added. If
It is about 2.7 times.

From the above, black soil (6) is effective in increasing the biological activity even if the type and degree of contaminated soil are different, and especially when rice bran (1) is added together, it has a synergistic effect. You can see that it has improved dramatically.

According to the above-mentioned experimental results, in soil polluted with oil, the polluted oil content is generally decomposed by improving the biological activity of microorganisms. However, by adding rice bran, black soil and compost, , The biological activity was further improved. In addition, nitrogen and phosphorus as inorganic nutrients used as nutrients and commercially available biological agents have dramatically improved biological activity by adding rice bran, even if adding them alone is not effective. I was able to do it.

Therefore, rice bran is used as a polluted soil purifying agent, and rice bran is added as a polluted soil purifying agent by adding rice bran to a microbial source aged by a natural fermentation process such as black soil and compost. It has been found that it is effective to add rice bran to a nutrient consisting of nutrients for improving the biological activity of microorganisms in the contaminated soil, and to use it as a contaminated soil purifying agent.

In the above experiment, soil contaminated with oil was used, but microorganisms that decompose oil are not particularly selected and used. Since the action of rice bran is to bring out the biological activity of the microorganisms that are latent in the contaminated soil, so long as such microorganisms are present, it is also effective for pollutants other than oil.

Needless to say, it is more effective to use, as the microbial source to be added together with the rice bran, a microbial source known to decompose the pollutant of interest. Therefore, as the source of such microorganisms, the soil of the target polluted soil where the decomposition of the pollutant is preceded by the present invention may be used.

In the above experiment, when rice bran was added,
Experiments were carried out as it was by solid treatment by mixing with other additives and contaminated soil. In actual use, it can be mixed and used as it is. However, rice bran itself is not a source of microorganisms, so various pretreatments and processing that consider efficiency and convenience of use, such as slurrying by adding other additives and water with stirring and mixing, and drying are performed. Good.
In addition, a part of rice bran components may be removed or concentrated before use. In addition, other pretreatments and processings performed by general biodetergents can be similarly performed.

It is also effective that the additives to be added together with the rice bran are not simply mixed with the rice bran but are mixed and stirred in advance and the environment such as temperature and oxygen is adjusted to promote the culture of microorganisms. Is.

Next, a method for purifying contaminated soil using such a contaminated soil purifying agent according to the present invention will be described. The present inventor conducted various experiments and found that the optimum amount of rice bran added varies depending on the soil quality, state, degree of polluted soil, type of pollutant, and the presence or type of other additives. However, for contaminated soil, 0.05 to 1
% Addition was effective. However,
Since rice bran is naturally decomposed, the side effect of suppressing biological activity is not observed even if added in a large amount, and the upper limit can be determined in consideration of cost efficiency. Further, in the present invention, since rice bran is used to activate the reproduction and growth of microorganisms in the soil by its rich nutrients rather than decomposing the oil by itself, it is proportional when added in large amounts. Does not always have the effect. From experience, it is considered that adding 2% or more does not make much sense.

The method of addition and mixing is not particularly different from the general soil pollution purification method. That is, solid treatment, slurry treatment, in-situ treatment, treatment by bioreactor and the like can be adopted.

[0052]

As described above, in the invention described in claim 1, since rice bran, which is often discarded at the time of rice polishing, is used, it also promotes resource reuse and is made of an extremely inexpensive material. By using it, it is possible to treat contaminated soil. Further, since rice bran is an edible material, and eventually it is naturally decomposed in the treated soil, it has an effect that it can be used very safely also in the neighboring environment and the working environment.

In the invention described in claim 2, since the biological activity can be further improved by adding rice bran to the microbial source aged by the natural fermentation process, it is more excellent than the case where only rice bran is added. It has the effect of making it possible to purify contaminated soil.

In the invention according to claim 3, since the rice bran can be further improved by adding the rice bran to the nutrient containing a nutrient for improving the bioactivity of the microorganism in the contaminated soil, the rice bran can be further improved. It has the effect of making it possible to purify the contaminated soil, which is even better than the case where only it is added.

In the invention described in claim 4, the microorganism source is
Providing a contaminated soil purifying agent that can be effectively used to improve the biological activity of rice bran even if there are few microorganisms present in the contaminated soil by using black soil or compost that is safe in nature and can be obtained at low cost It has the effect of being able to.

According to the fifth aspect of the present invention, it is possible to provide an extremely safe and inexpensive method for purifying contaminated soil.

The inventions according to claims 6 and 7 have the effect of providing a method for purifying contaminated soil, which is capable of purifying contaminated soil more excellent than the case where only rice bran is added.

[Brief description of drawings]

FIG. 1 is a line graph showing the results of a first experiment.

FIG. 2 is a line graph showing the results of a second experiment.

FIG. 3 is a line graph showing the result of a third experiment.

FIG. 4 is a line graph showing the result of a fourth experiment.

[Explanation of symbols]

1-16 Line

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Claims (7)

[Claims] 1. A contaminated soil purifying agent using rice bran. 2. The contaminated soil purifying agent according to claim 1, wherein rice bran is added to a microbial source aged by a natural fermentation process. 3. The contaminated soil purifying agent according to claim 1, wherein rice bran is added to a nutrient containing a nutrient for improving the biological activity of microorganisms in the contaminated soil. 4. The contaminated soil purifying agent according to claim 2, wherein the microbial source aged by the natural fermentation process is black soil or compost. 5. Rice bran is added to and mixed with the contaminated soil,
A method for cleaning polluted soil for improving biological activity. 6. The method for purifying contaminated soil according to claim 5, wherein a microorganism source aged by a natural fermentation process is added together with rice bran. 7. The method for purifying contaminated soil according to claim 5, wherein a nutrient agent comprising a nutrient for improving the biological activity of microorganisms in the contaminated soil is added together with the rice bran.