Method of fertilizer production and neutralization of alkaline combustion ash

Abstract

To provide a fertilizer production method or the like for providing a fertilizer more convenient than a conventional one by relaxing restriction on use due to strong alkalinity of conventional combustion ash.SOLUTION: The method for producing a fertilizer using alkaline combustion ash includes a raw material mixing step of mixing the alkaline combustion ash, organic matter and spawn to obtain a fertilizer raw material and a fermentation step of putting the fertilizer raw material into a fermentation tank and fermenting the fertilizer raw material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing fertilizer and a method for neutralizing alkaline combustion ash, and more particularly to a method for producing fertilizer using alkaline combustion ash. [Background technology]

[0002] Combustion ash generated by biomass power generation and the like has conventionally been effectively utilized for fertilizer and soil improvement.

[0003] For example, Patent Document 1 describes a technology that aims to improve the utility value of combustion ash as fertilizer by incorporating fertilizer components into the entire combustion ash produced by the combustion of biomass fuel, regardless of the particle size of the combustion ash. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-150958 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because conventional combustion ash is highly alkaline, it converts the nitrogen contained in other fertilizers into ammonia and volatilizes it. This makes it difficult to mix with other fertilizers. Also, because conventional combustion ash is highly alkaline, care must be taken to avoid alkalizing the soil by using it too much.

[0006] Therefore, an object of the present invention is to provide a fertilizer production method and the like that alleviates the restrictions on use imposed by the strong alkaline nature of conventional combustion ash and produces a fertilizer containing components derived from combustion ash that is easier to use than conventional fertilizers. [Means for solving the problem]

[0007] A first aspect of the present invention is a method for producing a fertilizer using alkaline combustion ash, the method including: a raw material mixing step of mixing the alkaline combustion ash, organic matter, and a seed culture to prepare a fertilizer raw material; and a fermentation step of placing the fertilizer raw material in a fermenter tank and fermenting it.

[0008] A second aspect of the present invention is the fertilizer production method according to the first aspect, wherein the seed culture is obtained by adding bacteria to the organic matter in the raw material mixing step and subjecting the organic matter to a fermentation treatment in advance, so that the bacteria are in a state where they are more numerous than before mixing.

[0009] A third aspect of the present invention is the method for producing fertilizer according to the first or second aspect, wherein air is forcibly fed into the fertilizer raw material in the fermentation step.

[0010] A fourth aspect of the present invention is the method for producing a fertilizer according to any one of the first to third aspects, wherein in the raw material mixing step, a mixing ratio of the alkaline combustion ash to the organic matter is within a range of 1:1 to 1:2 on a dry matter basis.

[0011] A fifth aspect of the present invention is the method for producing a fertilizer according to any one of the first to third aspects, wherein in the raw material mixing step, the amount of the organic matter mixed is an amount that neutralizes alkaline substances contained in the alkaline combustion ash with carbon dioxide generated by fermentation of the organic matter, and the fertilizer raw material has a pH of 7 to 9.

[0012] A sixth aspect of the present invention is a method for neutralizing alkaline combustion ash, which comprises a raw material mixing step of mixing the alkaline combustion ash with organic matter and a seed culture to prepare an alkaline combustion ash mixture, and a fermentation step of placing the alkaline combustion ash mixture in a fermentation tank and fermenting it. [Effects of the Invention]

[0013] According to each aspect of the present invention, the alkaline combustion ash can be neutralized by carbon dioxide generated from the fermentation of organic matter in the fermentation process to produce a neutral or nearly neutral fertilizer. This makes the resulting fertilizer easy to mix with other fertilizers and eliminates the need to worry about alkalizing the soil due to excessive use.

[0014] In addition, the main components in alkaline combustion ash, such as calcium carbonate and potassium carbonate, can be carbonated through a chemical reaction with the carbon dioxide produced from the fermentation of organic matter during the fermentation process, making them available in a form that can be easily and safely absorbed by plants.

[0015] Furthermore, the organic matter used in the fermentation process itself is decomposed into smaller molecules in a relatively short period of time, which can contribute to the fertility of the soil.

[0016] Furthermore, according to the second or third aspect of the present invention, it is possible to further promote the fermentation of organic matter in the fermentation step.

[0017] Furthermore, according to the fourth aspect of the present invention, it is possible to easily prepare raw materials for providing fertilizer that has been sufficiently neutralized while maintaining a high concentration of inorganic components in alkaline combustion ash that are effective as fertilizer, thereby enabling efficient and effective use of raw materials.

[0018] Furthermore, according to the fifth aspect of the present invention, it is possible to reliably prepare a fertilizer raw material that has been subjected to a raw material mixing step at a pH that is neutral to weakly alkaline.

[0019] According to the sixth aspect of the present invention, alkaline combustion ash can be neutralized by carbon dioxide produced from the fermentation of organic matter in the fermentation process. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a flow chart showing a fertilizer production method according to the present invention. [Figure 2]FIG. 1 is a cross-sectional view showing an outline of a pile-type fermentation tank used in the fertilizer production method according to the present invention. [Figure 3] Figure showing the changes over time in fermentation temperature, residual oxygen concentration, carbon dioxide concentration, and ammonia concentration in the accumulated fermented matter. [Figure 4] Figure showing the changes over time in fermentation temperature, residual oxygen concentration, carbon dioxide concentration, and ammonia concentration in the accumulated fermented matter. [Figure 5] A table summarizing the chemical reactions expected in the fermentation process [Figure 6] FIG. 1 shows the results of component analysis of a fertilizer produced by the fertilizer production method according to the present invention. [Figure 7] Diagram showing the components contained in wood combustion ash DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following examples. [Example]

[0022] FIG. 1 is a diagram showing a flow of a fertilizer production method according to this embodiment.

[0023] First, alkaline combustion ash, organic matter, and seed culture are mixed to prepare a fertilizer raw material (an example of the "fertilizer raw material" and "alkaline combustion ash mixture" described in the claims of the present application) (an example of the "raw material mixing step" described in the claims of the present application).

[0024] Alkaline combustion ash can be combustion ash (wood ash) generated in biomass power generation, wood combustion ash obtained by burning bark and scraps generated as waste at sawmills, or combustion ash from livestock manure, etc.

[0025] Examples of organic matter that can be used include coffee grounds, tea grounds from Job's Wheat Brown Rice Tea, and beverage extraction residues such as soy milk pulp, vegetable processing residues, livestock manure, and activated sludge generated in food manufacturing factories.

[0026] The seed culture refers to a bacterium to be mixed with an organic material in the raw material mixing step. Preferably, the raw organic material is mixed with the bacterium and fermented in advance to produce a state in which the bacterium has increased in number compared to before mixing.

[0027] The mixing ratio of alkaline combustion ash and organic matter in the raw material mixing step should be such that the alkaline substances contained in the alkaline combustion ash can be neutralized by carbon dioxide generated by fermentation of the organic matter. This makes it possible to provide a fertilizer that is sufficiently neutralized while maintaining a high concentration of inorganic components in the alkaline combustion ash that are effective as a fertilizer. Therefore, the method described in this example can be considered an example of the "method for neutralizing alkaline combustion ash" set forth in the claims of this application.

[0028] Based on tests of metabolic rate through fermentation, it appears that the ratio of alkaline combustion ash to organic matter containing seed bacteria should be within the range of 1:1 to 1:2 on a dry matter basis. Since the aim is to use the inorganic components of the alkaline combustion ash as fertilizer, it is desirable to mix the alkaline combustion ash with organic matter in a ratio that allows for sufficient neutralization while ensuring a high concentration of inorganic fertilizer components in the final fertilizer.

[0029] Alternatively, an appropriate method for determining the amount of organic matter to be mixed with alkaline combustion ash may be to neutralize the alkaline substances contained in the alkaline combustion ash with carbon dioxide generated by fermentation of the organic matter, thereby making the fertilizer raw material have a pH of 7 to 9 (neutral to weakly alkaline). Therefore, in the raw material mixing step, the organic matter and seed culture may be mixed with the alkaline combustion ash until the fertilizer raw material has a pH of 7 to 9, or until this is expected to occur. To make this expected, for example, the pH may be measured after a predetermined time has elapsed since mixing the raw materials, and a determination may be made as to whether the pH has reached a predetermined range.

[0030] Next, the fertilizer raw material is placed in a fermenter and fermented (an example of the "fermentation step" described in the claims of this application).

[0031] 2 is a cross-sectional view showing an outline of a pile-type fermentation tank used in the fertilizer production method of the present invention. The fermentation tank has a floor piping for forced ventilation in the center of the floor, and is configured so that air can be supplied into the tank from the floor.

[0032] For 1 m of fertilizer raw materials placed in the fermentation tank, 3 Aerobic fermentation of the fertilizer raw materials is promoted by forcing 10 to 20 liters of air per minute through forced ventilation floor piping using a high-pressure blower.

[0033] 3 and 4 show the time-dependent changes in fermentation temperature, residual oxygen concentration, carbon dioxide concentration, and ammonia concentration in the fermented pile, with the horizontal axis representing the number of days since fermentation. The fermentation exhaust gas generated by fermentation was collected in a plastic bucket placed above the fermented pile, as shown in FIG. 2.

[0034] As shown in Figures 3 and 4, the temperature inside the fermenter rose over time due to metabolic heat generated by the proliferation of fermentation microorganisms, rising to 70-80°C in 2-5 days.

[0035] In addition, the fertilizer raw materials in the fermentation tank were turned over (reloaded) every 5 to 7 days, and this process was repeated 3 to 4 times to promote re-fermentation and ensure uniform fermentation.

[0036] Here, we will explain the chemical reactions that are assumed to occur during the fermentation process. Figure 5 is a table summarizing the chemical reactions that are assumed to occur during the fermentation process.

[0037] First, in the fermentation process, the proliferation of fermentation microorganisms in the fermenter produces carbon dioxide through respiratory metabolism, fermentation heat, steam (water), and organic acids as fermentation metabolites.

[0038] During the fermentation process, the carbon dioxide produced by the fermentation of organic matter neutralizes the alkaline combustion ash, making it possible to produce a neutral or nearly neutral fertilizer. The pH was around 12 on day 0 of the fermentation process, immediately after the raw material mixing process, but by day 14 of the fermentation process, the pH had dropped to around 8.5. This means that the resulting fertilizer can be easily mixed with other fertilizers and used, and there is no need to worry about alkalizing the soil due to overuse.

[0039] Furthermore, it is believed that the carbon dioxide and organic acids generated during the fermentation process undergo chemical reactions with the main components in the alkaline combustion ash, as shown in Figure 5. As a result, the main components in the alkaline combustion ash, such as calcium carbonate and potassium carbonate, become calcium bicarbonate and potassium bicarbonate (available forms) that are easily and safely absorbed by plants.

[0040] Furthermore, in the early stages of the fermentation process, some of the nitrogen contained in the organic matter is converted into ammonia by the alkaline combustion ash (stripping phenomenon). However, in the fertilizer production method of the present invention, rather than wasting it by volatilizing it as ammonia as in conventional cases where combustion ash is mixed with other fertilizers, some of the generated ammonia can be taken up as a nitrogen source for microbial growth and used as a raw material for microbial reproduction.

[0041] Furthermore, the ammonia produced by the stripping phenomenon not only serves as a nitrogen source for microbial growth, but is also absorbed as ammonium bicarbonate in the latter half of the fermentation process, decreasing over time. This series of fermentation processes is called alkaline fermentation, and the fermentation progresses at a rate (speed of microbial combustion) that is approximately twice as fast as normal fermentation.

[0042] Fig. 6 shows the results of a component analysis of the fertilizer produced by the fertilizer production method of the present invention. Fig. 7 shows the components contained in wood combustion ash. While the pH of wood combustion ash is 12.9, the pH of the fertilizer produced by the present invention is neutralized to 8.9.

[0043] In order to prevent the fermentation heat from rising too much, it is preferable to remove water vapor by blowing up the fermentation heat.

[0044] The produced fertilizer is piled up and stored in flexible containers. [Explanation of symbols]

[0045] 1: Fermentation tank, 3: Plastic bucket, 5: Accumulated fermented matter, 7: Floor piping for forced ventilation, 9: Air, 11: Fermentation exhaust gas

Claims

1. A fertilizer production method for producing fertilizer using alkaline combustion ash, comprising: a raw material mixing step of mixing the alkaline combustion ash, organic matter, and seed culture to prepare a fertilizer raw material; and a fermentation step of placing the fertilizer raw material in a fermenter tank and fermenting it.

2. 2. The fertilizer production method according to claim 1, wherein the seed culture is obtained by pre-fermenting the organic matter in the raw material mixing step with bacteria, thereby increasing the number of bacteria compared to before mixing.

3. 2. The method for producing fertilizer according to claim 1, wherein air is forcedly fed into the fertilizer raw material during the fermentation step.

4. 4. The method for producing a fertilizer according to claim 1, wherein in the raw material mixing step, a mixing ratio of the alkaline combustion ash to the organic matter is within a range of 1:1 to 1:2 on a dry matter basis.

5. 4. The method for producing a fertilizer according to claim 1, wherein in the raw material mixing step, an amount of the organic matter mixed is an amount that allows alkaline substances contained in the alkaline combustion ash to be neutralized by carbon dioxide generated by fermentation of the organic matter, and thereby the fertilizer raw material has a pH of 7 to 9.

6. A method for neutralizing alkaline combustion ash, comprising: a raw material mixing step of mixing the alkaline combustion ash with organic matter and seed bacteria to form an alkaline combustion ash mixture; and a fermentation step of placing the alkaline combustion ash mixture in a fermenter and fermenting it.

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