JP2022067352A - Compost and method of manufacturing the same - Google Patents

Abstract

To provide a compost and a method of manufacturing the same.SOLUTION: A compost includes at least one of carbide, water-soluble phosphoric acid, iron oxide(III), iron carbonate(III), and iron hydroxide(III). The compost may contain total phosphoric acid at a concentration of 1 wt.% or more and 21 wt.% or less, and a ratio of the water-soluble phosphoric acid to the total phosphoric acid may be 30% or more and 70% or less. A method of manufacturing the compost includes: mixing the carbide containing iron phosphate(III) and an organic fertilizer source to prepare a mixture; processing the mixture under an anaerobic condition; and mixing the mixture processed under the anaerobic condition and a base.SELECTED DRAWING: Figure 1

Description

One of the embodiments of the present invention relates to compost and a method for producing compost. For example, one embodiment of the present invention relates to a compost rich in water-soluble phosphoric acid and a method for producing the same.

Excretion from animals such as livestock can be used as an organic fertilizer source as a raw material for compost. For example, Patent Document 1 discloses that compost effective for plant growth can be produced by mixing feces, which is animal excrement, with steel slag containing calcium oxide, magnesium oxide, silicon oxide, manganese oxide, and the like. ing.

Japanese Unexamined Patent Publication No. 2012-180266

One of the objects of the embodiment of the present invention is to provide compost and a method for producing the compost. For example, one of the embodiments of the present invention is to provide a compost having a novel composition and a method for producing the compost. Alternatively, one of the embodiments of the present invention is to provide a compost rich in quick-acting water-soluble phosphoric acid and a method for producing the compost.

One of the embodiments of the present invention is a method for producing compost. This method involves mixing a carbide containing iron (III) phosphate with an organic fertilizer source to prepare a mixture, treating the mixture under anaerobic conditions, and treating the mixture under anaerobic conditions. Includes mixing with the base.

One of the embodiments of the present invention is compost. This compost contains charcoal, water-soluble phosphoric acid, and at least one of iron oxide (III), iron (III) carbonate, and iron (III) hydroxide.

A flow showing a method for producing compost according to one of the embodiments of the present invention. The schematic diagram of the manufacturing apparatus for manufacturing compost according to one of the embodiments of this invention. The conceptual diagram which shows the storage of carbon dioxide using the method for producing compost which concerns on one of the Embodiments of this invention.

Hereinafter, each embodiment of the present invention will be described with reference to the drawings and the like. However, the present invention can be carried out in various embodiments without departing from the gist thereof, and is not construed as being limited to the description contents of the embodiments exemplified below.

The drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the actual embodiment in order to clarify the explanation, but the drawings are merely examples and limit the interpretation of the present invention. It's not something to do.

As used herein, the term "phosphoric acid" not only means phosphoric acid in the narrow sense, that is, a compound represented by the chemical formula of H ₃ PO ₄ , but also phosphoric acid (H ₃ PO ₄ ) and various other substances. Phosphate, monohydrogen phosphate, dihydrogen phosphate. Therefore, for example, iron phosphate means not only iron phosphate but also iron monohydrogen phosphate and iron dihydrogen phosphate, and the iron ion contained therein may be divalent or trivalent, unless otherwise specified.

1. 1. Compost The compost according to one of the embodiments of the present invention comprises charcoal, water-soluble phosphoric acid, and an iron compound selected from iron oxide (III), iron (III) carbonate, and iron (III) hydroxide. Includes at least one of. Other components include water-insoluble phosphoric acid (for example, phosphoric acid that is insoluble in water and soluble in a 2% aqueous citric acid (ku-soluble phosphoric acid)), sulfur-containing compounds, and manganese-containing compounds, in addition to water. , A boron-containing compound, a fiber contained in an organic fertilizer source which is a raw material of compost, and the like may be contained. Hereinafter, each of these components will be described.

1-1. Carbide Carbide is a porous material containing carbon as a main component and having pores having a cross-sectional diameter of several nm to several tens of μm. The specific gravity of the carbide may be 0.05 g / cm ³ or more and 0.8 g / cm ³ or less, or 0.1 g / cm ³ or more and 0.5 g / cm ³ or less. The charcoal may contain zero-valent iron, or may contain iron compounds such as divalent or trivalent iron phosphate, iron chloride, iron sulfate, iron nitrate, iron oxide, and iron bromide. good. These irons and iron compounds are contained in carbides in a state of being adsorbed or supported on the surface of the carbides or in pores. The proportion of carbides contained in the compost is not limited, but is, for example, 2% by weight or more and 40% by weight or less, or 5% by weight or more and 35% by weight or less.

1-2. Water-soluble phosphoric acid Examples of water-soluble phosphoric acid include phosphates such as lithium phosphate, sodium phosphate, potassium phosphate, and ammonium phosphate, lithium monohydrogen phosphate, sodium monohydrogen phosphate, and potassium monohydrogen phosphate. Phosphate monohydrogen salts such as ammonium monohydrogen phosphate, lithium dihydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, dihydrogen phosphate such as ammonium dihydrogen phosphate, etc. are exemplified and representative. Examples include phosphates of alkali metals such as sodium phosphate and potassium phosphate, and monohydrogen phosphates of alkali metals such as sodium monohydrogen phosphate and potassium monohydrogen phosphate. These water-soluble phosphoric acids are contained in the compost in relatively high concentrations. Specifically, it may be contained in a concentration of 30% or more and 70% or less, 40% or more and 60% or less, or 40% or more and 50% or less with respect to the total phosphoric acid in the compost. The total phosphoric acid refers to the whole of water-soluble phosphoric acid and water-insoluble phosphoric acid, and is contained in the compost at a concentration of 1% by weight or more and 21% by weight or less or 5% by weight or more and 15% by weight or less.

The concentration of water-soluble phosphoric acid can be determined, for example, by using the ammonium vanadomolybdate absorptiometry. In this method, for example, water is added to compost, and a predetermined amount of water-soluble portion is collected as a sample. Nitric acid (1 + 1) is added to this sample and heated to hydrolyze non-orthophosphate to orthophosphate ions. Then, ammonium vanazine (V) acid, hexaammonium heptamolybdate and nitric acid are added to produce phosphorus vanado molybdate. Water-soluble phosphoric acid is quantified by measuring the absorption of phosphobanado molybdate (for example, absorption at 420 nm) using an ultraviolet / visible spectrophotometer.

For the quantification of total phosphoric acid, the ammonium vanadomolybdate absorptiometry can be used. For example, a predetermined amount of compost is decomposed with nitric acid or perchloric acid, and then ammonium vanazine (V) acid, hexaammonium heptamolybdate, and nitric acid are added. Total phosphoric acid is quantified by measuring the absorption of the produced phosphobanado molybdate (for example, absorption at 420 nm) using an ultraviolet-visible spectrophotometer.

1-3. Iron Compounds Iron compounds include at least one of iron oxide (III), iron (III) carbonate, and iron (III) hydroxide. The iron compound may be composed of a single compound or may be a mixture. In the compost, a part of the iron compound may be adsorbed or supported on the carbide, and the other part may be present in a state of being free from the carbide. The iron compound may be contained in the compost at a concentration of 0.1% by weight or more and 10% by weight or less.

1-4. Other components Examples of the water-insoluble phosphoric acid described above include calcium hydrogen phosphate, calcium dihydrogen phosphate, calcium phosphate, magnesium monohydrogen phosphate, magnesium phosphate and the like. These water-insoluble phosphoric acids are derived from, for example, compounds carried or adsorbed on carbides used as raw materials in the compost manufacturing process described later, and / or organic fertilizer sources.

Examples of the sulfur-containing compound include sulfates of alkali metals and alkaline earth metals. Examples of the manganese-containing compound include manganese salts such as manganese sulfate, manganese nitrate, manganese chloride, manganese carbonate, and manganese borate. Examples of the boron-containing compound include boric acid in addition to the above-mentioned manganese borate. The concentration of each of these sulfur-containing compounds, manganese-containing compounds, and boron-containing compounds in the compost may be, for example, 0.01% by weight or more and 1% by weight or less.

As described above, since the present compost contains water-soluble phosphoric acid at a relatively high concentration, the present compost can function as a fertilizer having an immediate effect on the growth of plants. In addition, this compost contains carbides, which are porous materials. Such carbides not only improve the moisturizing property of the soil, but also function as a bioreactor, and can supply nutrients, water, oxygen, etc. to the soil in a well-balanced manner by micro-animals and microorganisms that coexist in the pores. .. From this, this compost can also contribute to soil improvement.

2. 2. Method for Producing Compost Hereinafter, a method for producing the present compost according to one of the embodiments of the present invention will be described. The flow of this manufacturing method is shown in FIG.

2-1. Carbide (1) Preparation of carbide by carbonization of biomass First, the carbide is prepared. Specifically, organic substances such as biomass are heated at a low oxygen concentration. Here, biomass is a kind of organic substance, a substance derived from a living body and its metabolite. Biomass available in the preparation of carbides includes materials derived from wood. Specific examples thereof include plate-shaped and columnar wood, thinned wood, pruned waste wood, construction waste wood, powdered sawdust, and wooden molded products such as particle boats. There are no restrictions on the type of wood, and it may be sugi, cypress, or bamboo. Alternatively, rice husks, bagasse, agricultural waste such as corn stalks and leaves, and agricultural by-products such as straw, straw and hay are examples of biomass. Alternatively, plants such as hemp, flax, cotton, sisal, abaca, and palm hair, which are raw materials for fibers, are also mentioned as biomass. Alternatively, the biomass may be algae such as seaweed, food residue, or silage obtained from animal manure.

(2) Supporting the iron compound on the carbide Next, the iron compound is adsorbed or supported on the surface or in the pores of the carbide obtained by the carbonization of biomass. Specifically, the carbide is immersed in a solution or suspension containing an iron compound under normal pressure or reduced pressure atmosphere to adsorb or support the iron compound on the carbide. Examples of iron compounds include iron sulfate (II), iron sulfate (III) (including polyiron sulfate), iron nitrate (II), iron nitrate (III), iron chloride (II), iron chloride (III), and iron oxide. Typical examples include (II), iron oxide (III), iron bromide (II), iron bromide (III), iron (II) carbonate, iron (III) carbonate and the like.

Next, the carbide on which the iron compound is adsorbed or supported is heated. The heating temperature may be appropriately selected in the range of 100 ° C. or higher and 900 ° C. or lower, 500 ° C. or higher and 800 ° C. or lower, or 600 ° C. or higher and 750 ° C. or lower. Water is removed by heating to obtain an iron compound-supported carbide.

The carbides after immersion may be heated in a reducing gas atmosphere such as hydrogen or carbon monoxide. As a result, a part of the iron compound can be reductively thermally decomposed into a zero-valent iron metal, but a part of the iron compound is a divalent or trivalent iron compound, or a mixture thereof on the surface of the carbide and fine particles. Adsorbed or carried in the pores.

The content of iron in the iron-supported carbide is 1% by mass or more and 50% by mass or less, 3% by mass or more and 30% by mass or less, 5% by mass or more and 25% by mass or less, or 10% by mass or more. Immersion conditions and heating conditions may be adjusted so as to be 25% by mass or less. The iron contained in the iron compound-supported carbide can be quantified by, for example, an inductively coupled plasma mass spectrometer (ICP-MS).

(3) Preparation of iron phosphate-containing carbides Subsequently, the iron compound-supported carbides are brought into contact with water containing phosphoric acid (hereinafter referred to as treated water) to prepare iron phosphate-containing carbides. The treated water may be prepared by dissolving a phosphate such as sodium phosphate or potassium phosphate in water, or water in a body of water such as a river, a lake or the sea may be used as the treated water. For example, a container filled with iron-supported carbide may be installed in a river, lake, or sea, and the iron-supported carbide may be brought into contact with water in a body of water. As a result, phosphoric acid contained in the water of rivers, lakes and marshes reacts with the iron compound on the iron compound-supported carbide, and is adsorbed or supported by the carbide as iron (III) phosphate having low solubility in water. , Phosphoric acid and organic compounds containing phosphorus in the water area are removed. That is, by this method, not only the carbide containing iron phosphate can be prepared at low cost, but also water purification and water quality improvement in various water bodies can be performed at the same time.

2-2. Composting Continue to use iron phosphate-containing carbide as one of the raw materials for composting.

(1) Mixing with an organic fertilizer source First, the iron phosphate-containing carbide obtained by the above-mentioned method is mixed with an organic fertilizer source. There is no restriction on the amount of iron phosphate-containing charcoal with respect to the organic fertilizer source, but for example, if 10% by weight or more and 40% by weight or less or 15% by weight or more and 25% by weight or less of iron phosphate-containing charcoal is added to the organic fertilizer source. good. If the viscosity of the obtained mixture (primary mixture) is high, water may be further added to adjust the viscosity. Examples of organic fertilizer sources include easily decomposable organic substances derived from living organisms, such as animal feces and urine such as cow dung, pig feces, and chicken feces, food waste such as food residues, agricultural waste, swill, and sludge. Can be mentioned. For the determination of whether or not it is an easily decomposable organic matter, for example, the amount of carbon dioxide generated after mixing with soil and the content of acidic detergent-soluble organic matter (AD-soluble organic matter) can be used as one of the indexes.

The carbon dioxide generated from the organic fertilizer source may be quantified by adding water to a mixture of a predetermined amount of sample and soil, starting the culture, and quantifying the carbon dioxide generated during the culture. The generated carbon dioxide may be collected with an aqueous solution of sodium hydroxide, and barium chloride is added thereto to precipitate it as barium carbonate, and barium carbonate is titrated with hydrochloric acid to quantify carbon dioxide. For example, if the amount of carbon dioxide generated 10 days after the start of culturing is 200 mg or more, 300 mg or more, or 400 mg or more per 1 g of the dried sample, this sample is an easily decomposable organic substance, and this compost is produced. It can be judged that it can be used as an organic fertilizer source for.

To quantify AD-soluble organic matter, for example, the sample is boiled in an acidic detergent solution (for example, a solution in which 20 g of cetyltrimethylammonium bromide is dissolved in 1 L of 0.5 mol / L sulfuric acid) for 1 hour and filtered. The residue is washed, dried and weighed. Then, the residue is incinerated and weighed, and the weight difference from that before incineration is determined as the amount of acidic detergent fiber (ADF). Since the AD-soluble organic substance is an organic substance other than ADF, the AD-soluble organic substance is calculated by subtracting the weight of ADF and the residue after ashing from the sample weight. If the amount of the AD-soluble organic matter thus obtained is 500 mg or more, 600 mg or more, or 700 mg or more per 1 g of the dried sample, this sample is an easily decomposable organic matter and is an organic substance for producing the present compost. It can be judged that it can be used as a fertilizer source.

However, in the embodiment of the present invention, the organic fertilizer source is not limited by the above-mentioned index and its numerical value, and any organic substance decomposed by an anaerobic microorganism can be used as an organic fertilizer source.

The mixing of the iron phosphate-containing carbide and the organic fertilizer source may be performed in a chamber that can be sealed or that can maintain anaerobic conditions, and there are no restrictions on the configuration or shape of the chamber. For example, as shown in FIG. 2, the iron phosphate-containing carbide and the organic fertilizer source are charged into the chamber 100 in which the hopper 104 is mounted. A screw feeder 106 for transporting the iron phosphate-containing carbide and the organic fertilizer source to the chamber 100 may be provided between the hopper 104 and the chamber 100. In order to promote decomposition by anaerobic microorganisms, the chamber 100 may be configured to be rotatable, or a stirrer 102 may be provided in the chamber. The chamber 100 may be configured to be hermetically sealed so as to shut off the outside air. Further, although not shown, the chamber 100 may be provided with one or more openings for adding water to the inside of the chamber 100 or for replacing the gas in the chamber 100. Further, in an anaerobic environment, it is not always necessary to mix the iron phosphate-containing carbide and the organic fertilizer source in the chamber. For example, an iron phosphate-containing carbide and an organic fertilizer source may be deposited and fermented to create an anaerobic environment inside.

(2) Anaerobic treatment Subsequently, the primary mixture obtained by mixing the iron phosphate-containing carbide and the organic fertilizer source is treated under anaerobic conditions to decompose the organic matter contained in the organic fertilizer source. This anaerobic treatment may be performed in the chamber 100 or in a chamber different from the chamber 100. The anaerobic treatment may be carried out by the action of anaerobic microorganisms contained in the organic fertilizer source, but in order to promote the decomposition of organic matter, anaerobic microorganisms may be added separately. Examples of anaerobic microorganisms include nitrate-reducing bacteria, iron-reducing bacteria, sulfate-reducing bacteria, acid-producing bacteria, acetic acid-producing bacteria, methanogen-producing archaea, and the like, and iron-reducing bacteria and methanogen-producing archaea are preferable. The anaerobic treatment may be performed at the temperature of the external environment in which the chamber 100 is placed, or may be performed while heating using a heater (not shown). When heating, the temperature may be, for example, 30 ° C. or higher and 60 ° C. or lower. The time for anaerobic treatment can also be arbitrarily set, and may be appropriately selected from the range of, for example, 1 day or more and 120 days or less, 10 days or more and 60 days or less, or 15 days or more and 30 days or less.

In this anaerobic treatment, the inside of the chamber 100 becomes a reducing environment with the decomposition of the organic substance, and the redox potential (ORP) of the primary mixture becomes negatively large. Therefore, the trivalent iron phosphate is reduced to the divalent iron phosphate. Therefore, when an iron-reducing bacterium that utilizes a trivalent iron compound as an electron acceptor is contained, the trivalent iron phosphate contained in the iron compound-containing carbide is subjected to the action of the iron-reducing bacterium and is divalent phosphorus. It is reduced to iron acid. Since divalent iron phosphate has a higher solubility in water than trivalent iron phosphate, iron phosphate is at least partially dissolved in water contained in the primary mixture, and divalent iron ions and phosphorus are dissolved. Dissociates into acid ions. For example, when the trivalent iron phosphate contained in the iron compound-containing carbide is FePO ₄ , divalent iron phosphate Fe ₃ (PO ₄ ) ₂ is produced.

(3) Addition of base Subsequently, the base is mixed with the anaerobic-treated primary mixture. As the base, an anion that gives an iron compound having low solubility in water by binding to a trivalent iron ion and a base that is ionically bonded to a cation that binds to a phosphate ion and gives soluble phosphate are used. Can be done. Specific examples thereof include alkali metal hydroxides, alkali metal carbonates, and alkali metal hydrogen carbonates. The base may be added as an aqueous solution or may be added in a solid state. Ion exchange occurs due to the addition of the base, and the divalent iron ion and phosphate ion dissociated by the anaerobic treatment are ionically bonded to the anion and cation of the base, respectively. For example, when an alkali metal hydroxide is used as a base, an alkali metal salt of phosphoric acid is produced and divalent iron hydroxide is produced. When an alkali metal carbonate or hydrogen carbonate is used as a base, an alkali metal salt of phosphoric acid is produced, and divalent iron carbonate and hydrogen carbonate are produced, respectively.

The addition of the base may be carried out in the chamber 100 in which the organic fertilizer source and the carbide containing the iron compound are mixed, or may be carried out in a chamber different from the chamber 100. For example, as shown in FIG. 2, the primary mixture may be conveyed to the chamber 110 connected to the chamber 100 via a valve 108 such as a rotary valve, and the base may be charged into the chamber 110. Although not shown, the chambers 100 and 110 may not be connected to each other. Similar to the chamber 100, the chamber 110 may be provided with a hopper 112 or a stirrer 114, and may be further provided with a screw feeder (not shown). The mixture (secondary mixture) obtained by completing the mixing with the base may be taken out from the chamber 110 by using a valve 116 such as a rotary valve.

The above (2) anaerobic treatment and (3) addition of a base may be performed at the same time. For example, a base may be added to a primary mixture obtained by mixing an iron phosphate-containing carbide and an organic fertilizer source, and then the mixture may be treated under anaerobic conditions to decompose the organic matter contained in the organic fertilizer source. Alternatively, the iron phosphate-containing carbide, the organic fertilizer source, and the base may be mixed and then treated under anaerobic conditions to decompose the organic matter contained in the organic fertilizer source.

(4) Sterilization treatment Although the compost according to one of the embodiments of the present invention can be produced by the above steps, the sterilization treatment may be continued. The sterilization treatment is preferably carried out by treating the compost in an oxidative atmosphere. The treatment in an oxidative atmosphere may be performed, for example, by bringing a gas containing oxygen (oxygen gas, air) into contact with the compost (aeration). At this time, the compost may be further irradiated with ultraviolet rays. By this sterilization treatment, bacteria and microorganisms contained in the organic fertilizer source can be removed or reduced. Further, the water contained in the organic fertilizer source or the water added separately can be evaporated to appropriately control the water content, and as a result, a compost that is easy to handle can be obtained.

As described above, the phosphate ion liberated from the divalent iron phosphate generated by the anaerobic treatment reacts with the cation of the added base, and the phosphate of the alkali metal, the monohydrogen phosphate, and the phosphate are used. Give dihydrogen salt. Since these salts are water-soluble, the compost according to one of the embodiments of the present invention functions as an excellent source of water-soluble phosphoric acid and can contribute to the growth of plants as a fast-acting fertilizer.

On the other hand, the iron ion (II) liberated from the divalent iron phosphate generated by the anaerobic treatment reacts with the anion of the base, and the divalent iron compound (iron hydroxide (II), iron (II) carbonate, (Iron (II) carbonate, etc.) is produced. This divalent iron compound is rapidly oxidized by the oxygen contained in the primary mixture or the secondary mixture, or by the oxygen in the oxidizing atmosphere in the sterilization treatment, and the trivalent iron compound (iron hydroxide (III), carbonic acid). Iron (III), iron oxide (III), etc.). For example, iron (II) hydrogen carbonate present in water is also oxidatively decomposed to give iron (III) hydroxide. Since these trivalent iron compounds have low solubility in water, they precipitate in compost. Therefore, the frequency factor of the reaction (ion exchange) between the precipitated trivalent iron compound and the water-soluble phosphoric acid is extremely small, and these reactions are very slow. As a result, the water-soluble phosphoric acid is hardly eliminated by the precipitated trivalent iron compound, and the compost can maintain the function as a fast-acting fertilizer.

(5) Other Steps The obtained compost may be used alone as a fertilizer, or may be used after being mixed with the above-mentioned sulfur-containing compound, manganese-containing compound, or fertilizer aid containing a boron-containing compound. .. In this case, the fertilizer aid may be added so that the concentration of the sulfur-containing compound, the manganese-containing compound, or the boron-containing compound in the compost is, for example, 0.01% by weight or more and 1% by weight or less. Mixing may be performed using a mixer, and the mixer can be arbitrarily selected from a freefall mixer, a forced mixer, a Y-branch mixer, an agitator mixer, a paddle mixer, and the like.

Further, the obtained compost may be dried, molded or the like. In molding, the compost may be processed into any shape such as pellets, rods, granules, and powders. If necessary, compost may be crushed or classified in order to adjust the particle size of the compost. For example, the compost may be crushed and classified so that the average particle size is 10 mm or less or 0.1 mm or more and 10 mm or less. Crushing may be performed using a crusher, for example, a crusher such as a vibration mill, jet mill, ball mill, roller mill, rod mill, hammer mill, impact mill, rotary mill, pin mill, pin-disc mill, or planetary mill. It can be used. Crushing the compost with a crusher increases the surface area, which in turn promotes the elution of water-soluble phosphoric acid into the soil. The classification is performed using a classification machine, and either a dry classification type classification machine or a wet classification machine may be adopted as the classification machine. For example, an air flow classifier, a gravitational field classifier, an inertial force field classifier, a centrifugal force field classifier, and the like are exemplified as classifiers.

Since the compost according to one of the embodiments of the present invention produced by the above-mentioned method is rich in water-soluble phosphoric acid, it exhibits an immediate effect comparable to that of chemical fertilizers and can function as a fertilizer suitable for top dressing. can. In addition, since the main components, carbides and organic fertilizer sources, are derived from natural resources, it is possible to recognize that the farming method using this compost is a kind of organic farming method.

Further, carbonization as a main component can be obtained by carbonization of biomass. That is, carbides are prepared by effectively utilizing the biomass derived from plants produced by the fixation of carbon dioxide by photosynthesis. Furthermore, the water quality of various water systems can be improved in the process of producing compost using this carbide, and by spraying this compost on the soil, carbon dioxide fixed by plants can be stored in the ground as carbide. can.

More specifically, as shown in FIG. 3, according to each embodiment of the present invention, biomass is carbonized to prepare a carbide (1), and further, a carbide carrying an iron compound is prepared from the carbonized material (1). 2). This iron compound-bearing carbide contributes to water purification when converted to iron phosphate-containing carbide (3), and through a series of processes including mixing with an organic fertilizer source, anaerobic treatment, and mixing with a base. It is converted to compost containing carbides originating from biomass (4). This compost is sprayed on the soil as a fast-acting fertilizer and used for plant growth (5). Plants fix carbon dioxide in the atmosphere by photosynthesis, provide food and structural materials, and by-produce biomass, which is a raw material for carbides (6).

By the cycle constructed by the series of processes (1) to (6), carbon dioxide in the atmosphere is immobilized as an organic matter by photosynthesis, and this organic matter is used as food or material and biomass is produced as a by-product. .. Biomass is converted to carbide by carbonization and finally distributed underground as compost. Therefore, carbon dioxide in the atmosphere is stored in the ground as carbon, which contributes to the reduction of carbon dioxide in the atmosphere. In addition, by using a carbonate as a base in the production of this compost, carbon dioxide can be further fixed as iron carbonate, which can further contribute to the reduction of carbon dioxide in the atmosphere. ..

1. 1. Preparation of Iron Phosphate-Containing Carbonized Material 400 g of carbonized material obtained by carbonizing wood derived from cedar is put into a 10 L aqueous solution of ferric sulfate (II) (iron content 11%), and the gauge pressure is usually zero. Soaked at −0.09 MPa at room temperature for 10 minutes. Then, the carbide was dried at 105 ° C. for 24 hours, and further heated at 900 ° C. for 1 hour in the presence of nitrogen and carbon monoxide gas to obtain an iron compound-supported carbide. The iron content in the iron compound-containing carbide is determined by treating the crushed iron compound-bearing carbide according to JIS K 1474 to extract iron, and the content of the extracted iron is determined by an inductively coupled plasma emission spectrophotometer (PerkinElmer). Manufactured by Optima 5300 DV). As a result, it was confirmed that 21% by weight of iron was contained with respect to the total amount of the charcoal-supported iron compound.

A sewage sludge dewatering separation solution was passed through a column packed with 2 kg of iron compound-supported carbide at a flow rate of 2 L / day for 4 days. The sewage sludge dehydration separation solution used here is a filtrate obtained by centrifuging the sludge at a sewage treatment plant in Kanagawa Prefecture. Then, the obtained iron phosphate-containing carbide was dried at 105 ° C. for 8 hours.
2. 2. Example 1
In this example, the result of treating the iron phosphate-containing carbide under anaerobic conditions will be described.
2-1. Experiment 40 mL of water, 5 g of iron phosphate-containing carbide, and 2 g of paddy soil were added to a 200 mL polypropylene container. Further, 1 g of dog feed (Pedigire (registered trademark) manufactured by MARS) was added as an organic fertilizer source, and the obtained primary mixture was stirred. Then, 1 g of an organic fertilizer source was added every day, and stirring was continued for 13 days. The total amount of organic fertilizer source was 13 g. As Comparative Example 1, 2 g of charcoal produced as a by-product in a gasification power generation device and 1.5 g of iron (III) phosphate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., iron (III) n hydrate) are contained in iron phosphate. A similar experiment was performed using it instead of the charcoal.

The pH of the obtained primary mixture was measured using a pH meter (measurement method model JF25 manufactured by HORIBA), and the redox potential ORP was measured using a glass electrode type hydrogen ion concentration indicator D-52 manufactured by HORIBA. The total amount of iron and the amount of iron in the water-soluble portion were measured in the same manner as in the measurement of the iron content of the carbide carrying the iron compound. In the measurement of the total iron amount, a sample sampled in a state where the primary mixture was uniformly stirred was used. On the other hand, in the measurement of the amount of iron in the water-soluble portion, the mixture was filtered and the obtained filtrate was used as a sample.

2-2. Results and discussion Table 1 shows the measurement results of the primary mixture. As shown in Table 1, there is no significant difference in pH and ORP between Example 1 and Comparative Example 1. The initial pH of the primary mixture in Example 1 and Comparative Example 1 was 9.1 and 9.2, respectively, and the pH after 13 days was significantly lower than these initial pH. This result means that a reducing environment is obtained by the action of anaerobic microorganisms contained in the paddy soil used in Example 1 and Comparative Example 1. Here, when the weight ratio (W _Fe / T _Fe ) of iron in the water-soluble portion to the total iron is compared, it can be seen that Example 1 is extremely higher than Comparative Example 1. The low W _Fe / T _Fe in Comparative Example 1 is considered to be because iron phosphate (III) derived from the reagent has a strong binding force between iron ions and phosphate ions and is hardly dissolved in the primary mixture. On the other hand, the reason why high W _Fe / T _Fe was obtained in Example 1 is that the iron phosphate (III) supported on the carbide was generated by the bond at room temperature, so that the binding force between the iron ion and the phosphate ion was strong. It is thought that it is weak and highly soluble.

The above results show that the reduction of iron phosphate (III) rapidly progresses in the primary mixture of iron phosphate-containing carbide and organic fertilizer source due to the action of anaerobic microorganisms, and iron phosphate (II) is soluble in water. Suggests that it is produced efficiently.

3. 3. Example 2
In this example, the result of mixing the base after treating the primary mixture of the iron phosphate-containing carbide and the organic fertilizer source under anaerobic conditions will be described.

3-1. The primary mixture was treated under anaerobic conditions for 13 days in the same manner as in Experimental Example 1. After this, sodium carbonate was added to the primary mixture, and then the mixture was stirred for 24 hours. The amount of sodium carbonate added was changed to 4.5 g, 9.0 g, and 22.5 g to obtain secondary mixtures of Examples 2 to 4, respectively.

The pH, ORP, total iron amount, and iron amount in the water-soluble portion were measured in the same manner as in Example 1. Both the total phosphoric acid concentration and the phosphoric acid concentration in the water-soluble portion were measured by the ammonium vanadomolylate absorptiometry. As the ultraviolet / visible spectrophotometer, 〇〇UV-2600 manufactured by Shimadzu Co., Ltd. was used.

3-2. Results and discussion Table 2 shows the analysis results. As shown in Examples 2 to 4 in Table 2, the addition of sodium carbonate tends to increase the weight ratio (W _Fe / T _Fe ) of iron in the water-soluble portion to the total amount of iron. This is because by adding sodium carbonate, carbon dioxide gas is generated in the secondary mixture, the anaerobic reaction is promoted, the iron reduction reaction proceeds, and the iron (II) ions in the water-soluble part increase. it is conceivable that.

The weight ratio W _p / T _p of phosphoric acid in the water-soluble portion to the total phosphoric acid in the secondary mixture increases as the amount of the base added increases. Further, in Comparative Example 2 to which no base was added, W _p / T _p was extremely low. This means that the phosphate ion derived from the water-soluble iron phosphate (II) generated by the treatment under anaerobic conditions ionically bonds with the alkali metal ion contained in the base, and the water-soluble phosphate in the secondary mixture. It shows that it exists as sodium.

The above results show that iron phosphate produced under anaerobic conditions was obtained by treating a mixture of a carbide containing iron phosphate and an organic fertilizer source under anaerobic conditions and then mixing it with a base containing an alkali metal as a cation. It is shown that the ion exchange between (II) and the base proceeds, and as a result, water-soluble phosphoric acid (alkali metal phosphate) is produced. From this, it is understood that compost containing abundant water-soluble phosphoric acid can be produced by applying the production method according to one of the embodiments of the present invention.

Each of the above-described embodiments of the present invention can be appropriately combined and implemented as long as they do not contradict each other. Those skilled in the art who appropriately add, delete, or change the design based on each embodiment are also included in the scope of the present invention as long as the gist of the present invention is provided.

Of course, other effects different from those brought about by each of the above-described embodiments, which are obvious from the description of the present specification or which can be easily predicted by those skilled in the art, are of course the present invention. It is understood that it is brought about by.

100: Chamber, 102: Stirrer, 104: Hopper, 106: Screw feeder, 108: Valve, 110: Chamber, 112: Hopper, 114: Stirrer, 116: Valve

Claims (14)

Mixing carbides containing iron (III) phosphate with an organic fertilizer source to prepare a mixture,
A method for producing compost comprising treating the mixture under anaerobic conditions and mixing the mixture treated under the anaerobic conditions with a base. The method of claim 1, further comprising treating the mixture mixed with the base in an oxidative atmosphere. The method according to claim 2, wherein the treatment in the oxidizing atmosphere is carried out by bringing the mixture mixed with the base into contact with air. The method of claim 1, further comprising adding an anaerobic microorganism to the mixture prior to mixing with the base. The method according to claim 1, wherein the carbide is prepared by contacting water containing phosphoric acid with a carbide containing an iron compound. The method of claim 1, wherein the organic fertilizer source comprises at least one of animal feces and food residue. The method according to claim 1, wherein the mixing of the carbide and the organic fertilizer source is performed so that the weight ratio of the carbide to the organic fertilizer source is 10% or more and 40% or more. The method of claim 1, wherein the base is selected from alkali metal hydroxides, alkali metal carbonates, and alkali metal bicarbonates. The method according to claim 1, wherein the mixing of the mixture and the base is carried out so that the molar ratio of the base to iron contained in the carbide is 10 or more and 20 or less. carbide,
A compost containing water-soluble phosphoric acid and at least one of iron (III) oxide, iron (III) carbonate, and iron (III) hydroxide. The compost according to claim 10, wherein the total phosphoric acid is contained in a concentration of 1% by weight or more and 21% by weight or less. The compost according to claim 11, wherein the ratio of the water-soluble phosphoric acid to the total phosphoric acid is 30% or more and 70% or less. The compost according to claim 10, which contains the carbide in a proportion of 2% by weight or more and 20% by weight or less. The compost according to claim 10, further comprising at least one of a sulfur-containing compound, a manganese-containing compound, and a boron-containing compound.

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