KR20030024230A - Biological-biodegrading adsorbent for removing hydrocarbon compounds such as oil and method for manufacturing thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological biodegradable adsorbent for the removal of oil and the like from the environment contaminated by oil or other hydrocarbon compounds (hereinafter referred to as oil, etc.) through adsorption and biodegradation. Biologically biodegradable adsorbent which inoculates excellent oil-degrading microbial agent into matrix (drafted rock powder) and immobilizes it, and then mixes it with the overdried natural organic phytmoss to adsorb oil and the like and biologically decomposes the adsorbed oil material. It relates to a manufacturing method. This adsorbent adsorbs oil from the sea or soil contaminated with oil at high speed and purifies the polluted environment by biodegrading the oil in a short time by the action of humic acid and oil-decomposing microorganisms which Pitmos itself contains. You can.

Description

BIOLOGICAL-BIODEGRADING ADSORBENT FOR REMOVING HYDROCARBON COMPOUNDS SUCH AS OIL AND METHOD FOR MANUFACTURING THEREOF}

The present invention relates to a biological biodegradable adsorbent for removing oil and the like from an environment contaminated by oil and other hydrocarbon compounds (hereinafter referred to as oil, etc.), and more particularly to an oil-degrading microbial agent having excellent oil resolution. After inoculating and immobilizing the matrix (medium rock powder), it is adsorbed oil as well as adsorbed oil by mixing with a surfactant composed mainly of over-dried natural organic peat moss and natural castor oil (castor oil) A biological biodegradable adsorbent for biologically degrading a substance and a method for producing the same.

Oil spilled on the ocean and on land by oil exploration, transportation accidents, or cleaning or deliberate spillage of factory wastes forms a film that blocks the transmission of oxygen or sun rays, increasing ecological or environmental damage. In addition to being a factor, the natural breakdown of spilled oil material is so late that it takes hundreds of years to completely remove it from nature. In addition, over time, the extent of pollution rapidly increases, so oil must be removed quickly before damaging the environment or ecosystem.

As a method of removing such an oil, there is a method of directly recovering spilled oil, a method of dispersing or neutralizing oil, etc., or a method using an adsorbent. However, the method of directly collecting, dispersing, or neutralizing the oil has a problem of low oil removal efficiency, and in the latter case, it causes a problem of secondary pollution. Therefore, it is common to remove oil by using various kinds of adsorbents. .

Currently, there are more than 190 kinds of general oil adsorbents in use around the world, which can be classified into inorganic adsorbents, synthetic or polymer adsorbents, and natural adsorbents according to their raw materials.

Kaolin and diatomaceous earth are used as inorganic adsorbents as the standard for industrial adsorbents, but they do not help the biodegradation of the adsorbed oil by leaching the adsorbed oil to contaminate the soil or groundwater. Kaolin and sand are also difficult to transport and dispose and cost excessive waste disposal. In addition, crystalline silica (silica) contained in kaolin is suspected of carcinogenicity, the situation in some developed countries are regulated by law as an adsorbent.

General synthetic polymer adsorbent is a product made of polypropylene and has the advantage of excellent hydrocarbon adsorption power and not absorbing a large amount of water. However, it consumes a lot of labor when using and cannot use equipment such as blower. Difficult to apply to large scale processing In addition, the synthetic polymer adsorbent does not completely retain the adsorbed hydrocarbons by the action of the external surface tension, so when oil is absorbed and delivered, the oil droplets are eluted and soil landfilling is impossible.

The most common natural organic adsorbents include wood chips, sawdust, cork, dry corn, hair, waste paper and processed peat moss. Although degreasing hair and sawdust are excellent in terms of adsorption power and adsorption speed, the transportation cost and waste disposal cost are high, and sawdust also causes secondary pollution because it dissolves the absorbed oil like the other types of adsorbents. Can absorb about eight times the weight of hydrocarbons, but it can cause detrimental effects because the cork itself is broken down.

By comparison, another natural adsorbent, peat moss, is originally a hydrophilic material or a bicarbonated peat moss buried in the middle layer through an ice age, which is oleophilic in contact with oils, etc. Not only does it adsorb, but above all, it does not elute the adsorbed oil material again. Also, since peat moss is itself a natural material and no longer decomposes, even if peat moss is contained in oil and so on, it does not cause any further environmental pollution. It is also easy to carry and economical in terms of price.

As described above, natural organic peat moss adsorbents have a lot of advantages as oil adsorbents. As described above, the organic organic peat moss adsorbent adsorbs immediately upon contact with water or various oils spilled onto the floor, thereby easily adsorbing the peat moss adsorbent to the contaminated area. Sprinkle oil to absorb oil and then use it as a method of incineration or landfilling, or in the case of soil contamination, evenly spray the pitmoss adsorbent onto the contaminated soil and then invert soil (rotary). It is also used as a way to carry out tillage. In addition, the oil adsorbed on the pit moss is biodegraded naturally by the humic acid contained in the pit moss over time, so the oil is treated more environmentally than other physical and chemical methods. I can do it and am attracting more attention.

However, contaminants such as oil adsorbed to peat moss and embedded in the soil, or contaminants such as oil remaining in the soil adsorbed to the peat moss after soil tillage work, especially tillage in the case of soil contamination, are naturally Waiting for biodegradation takes time and money to restore the soil to its natural state. Some expect their effects on the biological purification of oil-contaminated soils using petroleum hydrocarbon-degrading microbial agents, but this is a limited use that must be handled professionally, which can be costly in terms of time and cost. It is true.

Therefore, the present inventors reduce the need for a functional adsorbent which can be easily and efficiently treated by anyone, and minimize the time and economic losses if the research and development and practical use of a new biological biodegradable adsorbent including natural organic peat moss having excellent adsorption power and a powerful oil-degrading microbial agent. The present invention has been found to be able to treat oil and the like in an environmentally friendly manner.

In order to solve the above problems, the present invention is biologically biodegradable material such as pitmos and adsorbed oil over-dried so as to have an oleophilic capable of adsorbing oil, etc. It is an object of the present invention to provide a new biological biodegradable adsorbent comprising microorganisms having excellent oil resolution.

Another object of the present invention is to over-dry the peat moss to an appropriate moisture content in order to be able to quickly adsorb oil, etc., and inoculate the microbial agent into the matrix (medium rock powder) in order to preserve the oil decomposition ability of the oil-decomposing microorganism for a long time After the immobilization, the pitmoss and microorganisms are mixed to provide a method for preparing a new biological biodegradable adsorbent.

1 is a view showing the change in TPH concentration of contaminated soil over time.

The present invention

1) overdried peat moss; And

2) The present invention relates to a biological biodegradable adsorbent comprising a matrix to which an oil-degrading microbial agent is immobilized.

In an example of the present invention, 100 parts by weight of the overdried peat moss and 2 to 7 parts by weight, preferably 2 to 5 parts by weight, of the matrix to which the oil-degrading microbial agent is immobilized can be used. The pit moss may be pit moss manufactured by adding a surfactant to the pit moss having a water content of 30 to 50%, and the over dried pit moss may contain a water content of 7 to 9%. In an example of the present invention, 2 to 6 parts by weight of surfactant, preferably 2 to 4 parts by weight, may be used to 100 parts by weight of peat moss having a water content of 30 to 50%. Pitmoss may be used in the form of a powder having a particle size of mainly 120 mesh or more, and pitmoss is preferably selected from a brown forming layer of a middle layer of 1 meter or less and at least 1 meter deep from the ground.

In one example of the present invention, 2 to 5 parts by weight, preferably 3 to 5 parts by weight, of the oil-degrading microbial agent may be fixed to 100 parts by weight of the matrix. The matrix material of the present invention is preferably a live elvan rock powder having excellent porosity and microbial trapping power, and the particle size of the pulsar stone is suitably 150 to 200 mesh. In addition, the matrix material may be added 2 to 7 parts by weight, preferably 2 to 5 parts by weight to 100 parts by weight of the peat moss.

In addition, the surfactants usable in the present invention include alcohol-based nonionic surfactants, and castor oil is purified by alcohol.

In addition, the oil-degrading microorganisms usable in the present invention include oil-degrading Bacillus sp .

In addition, the present invention

(A) adding 2 to 6 parts by weight of the surfactant to 100 parts by weight of pitmos with a water content of 30 to 50%;

(B) drying the pit moss until the residual moisture content is 7 to 9%;

(C) inoculating 2 to 5 parts by weight of the oil degradation microbial agent to 100 parts by weight of the matrix to fix the microorganisms to the matrix; And

(D) It relates to a method for producing a biological biodegradable adsorbent comprising mixing 2 to 7 parts by weight of the matrix of the oil-decomposing microorganism of step (C) to 100 parts by weight of the dried peat moss of step (B).

Hereinafter, the present invention will be described in more detail.

Pitmos is originally a hydrophilic material, but the pitmos used in the present invention is overdried, so it becomes oleophilic, and when pitmos is sprayed onto a mixed solution in which water and oil are present at the same time, a large amount of oil is adsorbed first, and It has the ability not to leach the adsorbed oil even after the adsorption. In particular, in the present invention, the pit moss is suitably selected by using a sample taken from a brown forming layer of a middle layer part of 1 meter or less and at least 1 meter deep from the ground. Unlike the upper and lower pitmoss, the pitmoss contained in the middle layer contain humic acid, which not only promotes the oil decomposition process of microorganisms but also restores the soil to its original state earlier than the soil recovery time. This can also be done.

In one example of the present invention, the peat moss adsorbs about 7 to 8 times its own weight and does not elute the adsorbed oil unless an artificial pressure is applied from the outside.

Such pitmoss can adsorb a variety of oils and other hydrocarbon compounds, and are known to be superior to kaolin, which is a kind of inorganic adsorbent, in adsorption capacity for various hydrocarbon compounds. Oils that can be adsorbed by peat moss are shown in Table 1 below.

Table 1: Oil and other hydrocarbon compounds adsorbable by peat moss

The surfactant that can be used in the present invention is not particularly limited in its kind, but preferably alcohol-based nonionic surfactants, and more preferably alcohol-based refined alcohols using castor oil as a main component. Nonionic surfactants are used. Surfactants increase the internal surface area of porous peat moss and enhance the flexibility and elasticity of the fibre, ultimately helping the peat moss to absorb oils and the like more quickly. In particular, Pimaji oil is a vegetable oil, which is not harmful to the environment or living organisms, and increases oil absorption rate, thus being a preferred component of a surfactant.

The live elvan rock powder used as the matrix in the present invention has excellent porosity and excellent microbial capturing ability. It also contains various minerals on its own, and in particular, the amount of dissolved oxygen is enriched, so that it can be stored for a long time without degrading the oil degradation activity of microorganisms.

The microorganism that can be used in the present invention is not particularly limited as long as it has an oil resolution, but is preferably a microorganism of Bacillus sp. Or Pseudomonas sp . The oil-degrading microorganism used in the present invention is a Bacillus sp. LU1 strain (obtained from ECO Solution) and used as a high concentration microbial agent of 1 × 10 ⁹ CFU / ml. Generally, it is reported that at low temperature, the hydrocarbon state becomes a solid state or the viscosity is increased, so that the surface area is reduced, which makes it difficult to decompose hydrocarbons by microorganisms. It may be a preferred strain for biological purification of soil or ocean contaminated with or the like.

Referring to the step of producing a biological adsorbent of the present invention in more detail as follows.

1.Adding 2 to 6 parts by weight of surfactant to 100 parts by weight of pitmos with a water content of 30 to 50%

The peat moss according to the present invention can be used by collecting a brown bicarbonate material that is buried in a middle layer portion of 1 meter or less from the ground and at least 1 meter deep. The moss buried in the upper layer is composed of fibers which are less carbonized but not completely decomposed, which can cause the generation of harmful gases in the process of decomposing. have. In addition, moss buried in the lower layer is excessively evolved to a state just before coal or petroleum, so that porous fiber is destroyed, powdered, and the amount that can be adsorbed is extremely low, so the adsorption capacity cannot be expected.

On the other hand, moss buried in the middle layer is a fiber composed of humic acid as the carbonization progresses, and the humic acid lump acts as an important catalyst for decomposing oil along with natural microorganisms. Therefore, the oil material adsorbed in the peat moss is biodegradable, but since the peat moss itself is no longer biodegradable as a humic acid substance, even if the peat moss is left in the soil with the oil component, it does not cause any further environmental pollution. Due to this property, pitmoss, which are excellent in oleophilic, can encapsulate a large amount of oil and encapsulate it, and can be buried in a middle layer capable of biodegrading oil with a large amount of humic acid, are preferred as the oil adsorption material of the present invention. In other words, the peat moss buried in the middle layer contains the natural organic humic acid, which not only promotes the oil decomposition process of microorganisms but also plays a role of restoring the soil to its original state earlier than the soil recovery time. It is a material suitable as an optimal fit moss.

Processed peat moss collected from a suitable middle buried layer generally contains 30 to 50% moisture. The addition of an optional surfactant to the water-containing peat moss increases the internal surface area of the porous peat moss and enhances the flexibility and elasticity of the fiber, ultimately allowing the oil and the like to be absorbed more rapidly. In particular, alcohol-based nonionic surfactants, which are castor oil used in the present invention as a main component and refined with alcohol, are environmentally friendly and have a high oil adsorption rate since the main component is vegetable oil. It is suitable to use 2 to 6 parts by weight of surfactant, preferably 2 to 4 parts by weight, in 100 parts by weight of pitmos with a water content of 30 to 50%. In order to uniformly distribute the surfactant in the peat moss powder, the surfactant diluted with 50 times liquid may be evenly sprayed and mixed.

2. drying the pit moss until the residual moisture content is 7-9%

After the step 1, the peat moss containing the surfactant is naturally dried until the moisture content is about 25%, and then air-dried for at least 10 minutes at a temperature of 150 ° C. or higher and 220 ° C. or lower for 7 to 9%. Over-dried until it is then screened to screen size of 120 mesh or more to screen the powder with a constant pore size. Since peat moss is a brown material, it is a good condition to dry naturally. Thus, evaporation of water to some extent is possible in the natural state without artificial manipulation. Also, in consideration of economical efficiency such as fuel cost, up to 25% of moisture content is dried in the natural state. The method of using a dryer is advantageous mechanically and practically.

As mentioned above, since peat moss is inherently hydrophilic and converted to oleophilic in an overdried state, it is necessary to reduce the water content of the peat moss as much as possible. The range of 7 to 9% of water content of the peat moss according to the present invention is to minimize the moisture content as compared to the commercially available water content of 30 to 50% of the moisture content, and further reduction of moisture is more likely to scatter the peat moss powder. It is difficult to handle by scattering and also difficult to mix with the microbial agent in the next step.

3. Inoculating 2-5 parts by weight of the oil degradation microbial agent to 100 parts by weight of the matrix to fix the microorganisms to the matrix

Pitmos powder is not suitable for the growth and preservation environment of microorganisms because it is overdried with a moisture content of 7 to 9%. Therefore, when inoculating the oil-decomposing microorganisms to the pitmos itself, it is difficult to long-term preservation of the microorganism oil-decomposability, it is difficult to achieve the object of the present invention. Thus, in order to increase the survival rate of the oil-degrading microorganisms and maintain the oil-degrading activity, a matrix is required to immobilize the microorganisms. Therefore, it is possible to select a mineral live elvan rock that is porous and contains a large amount of various mineral components as a matrix material for inoculating spawn. After pulverizing the elvan stone into a powder of 150 to 200 mesh, a microbial nutrient such as a supplementary filler is mixed with 1 × 10 ⁹ CFU / ml of high concentration oil-degrading microbial agent, sprayed by spraying, mixed and mixed at about 20 ° C. Incubate at least 1 week at room temperature to immobilize the microbial preparation in the elvan. At this time, the amount of the microorganism to be immobilized is 2 to 5 parts by weight, preferably 3 to 5 parts by weight of the microbial agent, to 100 parts by weight of the live elvan rock powder. As a result, most petroleum compounds showed the highest degradation rate when the inoculum was inoculated at 10%. However, when inoculated more than 3% to 5%, there was almost no difference in resolution. About 3 to 5 parts by weight of the microorganism inoculation is suitable.

4. mixing 2 to 7 parts by weight of the matrix in which the oil decomposition microorganisms in step 3 are fixed to 100 parts by weight of the dried step 2 peat moss

2 to 7 parts by weight, preferably 2 to 5 parts by weight of the matrix (dough rock powder) to which the oil-decomposing microorganisms are immobilized, are mixed by adding 100 parts by weight of the dried peat moss.

The biological biodegradable adsorbent according to the present invention is intended for use in soil contaminated by oil and the like, particularly in farmland and the ocean, and the purpose of adsorption and biodegradation can be simultaneously achieved by spraying the biological biodegradable adsorbent of the present invention in regions contaminated with oil and the like. Can be.

In one example of the present invention, when the biological biodegradable adsorbent according to the present invention is sprayed onto soil contaminated with oil or the like, it takes about three months for the oil to be biodegraded and the soil recovers to a cultivable state. In the case of the general peat moss adsorbent that does not include, the restoration period of the soil is about 6 to 18 months, although there is a difference depending on the type of oil source.

Hereinafter, the present invention will be described in more detail with reference to Preparation Examples and Examples. However, the following preparations and examples are merely illustrative and are not intended to limit the scope of the invention to them.

Preparation Example 1

1) 300 ml of a surfactant (prepared by refining castor oil with alcohol) adjusted to pH 7 with respect to 10 liters of peat moss having a water content of 30 to 50% was diluted with 50 times liquid, spray-sprayed, and stirred.

2) Pittmoss containing the surfactant is naturally dried in a well-ventilated area until the moisture content is about 25%, and then blow-dried at 220 ° C. for 10 minutes using a rotary kiln-type drum dryer. After adjusting to about 7%, pitmoss was selected in the form of a powder having a constant pore size by screen collecting the size of 120 mesh or more.

3) Inoculate the strain by spraying and stirring a spray of 300 g of 150-200 mesh sized agglomerate powder prepared by pulverizing 15 ml of a suspension of LU1 strain prepared at a high concentration of 1 × 10 ⁹ CFU / ml. The culture was fixed for one day to fix the strain on the elvan powder.

4) 10 l of pitmoss of step 2) and 300 g of ganbanite powder of step 3) were mixed to prepare a biological biodegradable adsorbent according to the present invention.

Preparation Examples 2 to 11

Steps 1) to 4) and except that the moisture content in the peat moss is changed to 9, 10, 15, 20, 25, 30, 35, 40, 45 and 50%, respectively, as shown in Table 2 below. Biodegradable adsorbents were prepared in the same manner.

10 L of each biodegradable adsorbent prepared was administered to a large vessel containing a mixture of 40 L of water and 40 L of oil, and then the time taken for oil adsorption was measured. Table 2 below shows the time taken for adsorption of water and oil according to the change of moisture content.

Table 2: Changes in Oil Adsorption Time with Water Content of Pitmoss

Production Example Moisture content (%) Time Moisture adsorption Oil adsorption Preparation Example 1 7 More than 3 days Immediately Preparation Example 2 9 More than 2 days Immediately Preparation Example 3 10 Within 48 hours 0.5 sec Preparation Example 4 15 36 hours 1 sec Preparation Example 5 20 24 hours 1.5 seconds Preparation Example 6 25 18 hours 2 sec Preparation Example 7 30 12 hours slowly Preparation Example 8 35 3 hours slowly Preparation Example 9 40 1 hours slowly Preparation Example 10 45 20 minutes Very slowly Preparation Example 11 50 3 minutes Machu slowly

Through Table 2, it is proved that the higher the dryness, ie, the lower the water content, of the pit moss, the larger the oil is adsorbed in a short time and the longer time is required for the water adsorption. This result is because the oil adsorption amount is reduced by the amount of water contained in the peat moss itself.

In other words, the lower the water content of the peat moss is floating in water for a long time, the water is excluded, the oil is immediately adsorbed and solidified to have a lipophilic property. In the case of the peat moss adsorbed moisture first, the late adsorbed oil is leached out. Therefore, in order to maximize and speed up the oil adsorption capacity, and to prevent leaching of the adsorbed oil, it is preferable to sufficiently dry the pit moss.

Example: Soil Treatment Using Biodegradable Adsorbents According to the Present Invention

A biological biodegradable adsorbent according to the present invention was prepared in the same manner as in Preparation Example 1 to attempt biological treatment of oil contaminated soil on a laboratory scale. The soil was collected and weighed with a thickness of 30 cm on the site of 3.306㎡ (1 pyeong), and the soil was contaminated with about 4,500 ppm of TPH (total petroleum hydrocarbon) based on diesel, which is hardly decomposable oil. Biodegradable adsorbent was applied. At this time, about 25% of the total soil volume was added to the biodegradable adsorbent.

Total petroleum hydrocarbon (TPH) was added to anhydrous sodium sulfate solution in 30 g of soil, extracted for 16 hours from 100 m of dichloromethyl / acetone 1: 1 solution, and the extract was analyzed by GC / FID. Table 3 is a table showing the change in TPH concentration of contaminated soil over time, Figure 1 is a graph showing Table 3. It can be seen that about 16 days after the experiment was conducted through Table 3 and FIG. 1, about 98.1% of the diesel biodegradation treatment was performed.

Table 3: Changes in TPH Concentrations of Contaminated Soils Over Time

time TPH (ppm) 1 day later 4,000 4 days later 2,850 8 days later 1,600 16 days later 85 or less

In this regard, in the case of treating contaminated soil using a general pitmoss adsorbent instead of the biodegradable adsorbent according to the present invention, approximately 91.5% of the hydrocarbon compound is biodegraded after about 16 days of implementation. It is proved that the effect of biodegradable adsorbent is more excellent. In addition, considering that diesel is a hardly decomposable substance compared to other hydrocarbon compounds, it can be seen that the effect of the present invention is relatively greater.

According to the present invention, when the contaminated soil is farmland, it is possible to cultivate it after about 3 months by using the biodegradable adsorbent according to the present invention, whereas when using only the peat moss adsorbent containing no microbial agent, the soil is so cultivable. It takes a period of 6 to 18 months to recover.

The present invention relates to a biological biodegradable adsorbent for removing oil and the like from an environment contaminated with oil and the like and a method for producing the same. The biological biodegradable adsorbent according to the present invention not only has excellent adsorption capacity for oil, but also has excellent biodegradability for adsorbed oil, thereby using the same to rapidly remove oil from an environment contaminated by oil, such as sea or soil. At the same time, it can purify the contaminated environment by biodegrading oils in a short period of time by the action of humic acid and oil-decomposing microorganisms that Pitmos itself contains. can do.

Claims (14)

1) overdried peat moss; And 2) A biological biodegradable adsorbent comprising a matrix immobilized with an oil degradation microbial agent. 2. The biological biodegradable adsorbent according to claim 1, comprising 100 parts by weight of overdried peat moss and 2 to 7 parts by weight of the matrix to which the oil degradation microbial agent is immobilized. The biological biodegradable adsorbent according to claim 1 or 2, wherein the pitmoss are pitmoss prepared by adding a surfactant to the pitmoss having a water content of 30 to 50% by overdrying. The biological biodegradable adsorbent according to claim 1 or 2, wherein said overdried pitmos has a water content of 7 to 9%. 4. The biological biodegradable sorbent of claim 3, wherein the pitmos prepared by overdrying has a moisture content of 7 to 9%. The biological biodegradable adsorbent according to claim 3, comprising 2 to 6 parts by weight of surfactant in 100 parts by weight of pitmos with a water content of 30 to 50%. The biological biodegradable adsorbent according to claim 1 or 2, wherein the pit moss is collected from a brown forming layer of a middle part of one meter or less from the ground. The biological biodegradable adsorbent according to claim 1 or 2, wherein 2 to 5 parts by weight of the oil degradation microbial agent is immobilized to 100 parts by weight of the matrix. The biological biodegradable adsorbent according to claim 1 or 2, wherein the matrix is a live elvan rock powder. 9. The biological biodegradable sorbent of claim 8, wherein said matrix is a live elvan rock powder. 10. The biological biodegradable sorbent of claim 9, wherein the pulsar powder has a particle size of 150 to 200 mesh. The biological biodegradable adsorbent according to claim 3, wherein the surfactant is an alcoholic nonionic surfactant in which castor oil is purified with alcohol. The biological biodegradable adsorbent according to claim 1 or 2, wherein the microorganism is a strain of Bacillus sp . (A) adding 2 to 6 parts by weight of the surfactant to 100 parts by weight of pitmos with a water content of 30 to 50%; (B) drying the pit moss until the residual moisture content is 7 to 9%; (C) inoculating 2 to 5 parts by weight of the oil degradation microbial agent to 100 parts by weight of the matrix to fix the microorganisms to the matrix; And (D) A method for producing a biological biodegradable adsorbent, comprising mixing 2 to 7 parts by weight of a matrix in which the oil-decomposing microorganism of step (C) is fixed to 100 parts by weight of dried peat moss of step (B).