compost

Abstract

To provide a compost in which an odor is depressed and a manufacturing method thereof.SOLUTION: A compost includes carbide, phosphorus, iron, and ammonia-oxidizing archaebacteria. In the compost, the total phosphate concentration is 2.0 wt.% or more and 5.0 wt.% or less, the iron concentration is 0.4 wt.% or more and 6.0 wt.% or less, and the number of the ammonia-oxidizing archaebacteria is 0.04% or more and 0.10% or less of the total number of bacteria. The carbide concentration may be 2 wt.% or more and 40 wt.% or less. The specific surface of the carbide may be 100 m2 / g or more and 900 m2 / g or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to compost. For example, one embodiment of the present invention relates to compost in which odor generation is significantly suppressed and to a method for producing the same. [Background technology]

[0002] Organic waste of biological origin, such as food scraps, animal excrement, and food residue, can be used as raw materials for compost. For example, Patent Document 1 discloses that compost can be obtained by mixing nitrogen-containing organic waste, activated carbon, and fermentation bacteria that decompose ammonia. Patent Document 2 discloses that compost can be obtained by mixing nitrogen-containing organic waste with microorganisms that have denitrification function and a fermentation accelerator. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2005-145769 [Patent Document 2] International Publication No. 2007 / 114324 [Overview of the project] [Problems that the invention aims to solve]

[0004] One embodiment of the present invention aims to provide compost and a method for producing the same. Alternatively, one embodiment of the present invention aims to provide compost having a novel composition and a method for producing the same. Alternatively, one embodiment of the present invention aims to provide compost with suppressed odor and a method for producing the same. [Means for solving the problem]

[0005] One embodiment of the present invention is compost. This compost contains carbonized material, phosphorus, iron, and ammonia-oxidizing archaea. The total phosphorus concentration of the compost is 2.0% by weight or more and 5.0% by weight or less, the iron concentration is 0.4% by weight or more and 6.0% by weight or less, and the ratio of the number of ammonia-oxidizing archaea to the total number of bacteria is 0.04% or more and 0.10% or less. [Brief explanation of the drawing]

[0006] [Figure 1] A flowchart illustrating a method for producing compost according to one embodiment of the present invention. [Figure 2] A conceptual diagram showing carbon dioxide storage using a composting method according to one embodiment of the present invention. [Figure 3] A graph showing the ammonia content in the compost of the example and comparative example. [Figure 4] A graph showing the content of Nitrosospää wiennesis in the compost of the example and comparative examples. [Modes for carrying out the invention]

[0007] The embodiments of the present invention will be described below with reference to the drawings and other materials. However, the present invention can be implemented in various forms without departing from its spirit, and is not to be interpreted as being limited to the embodiments described below.

[0008] In this specification, the term "phosphorus" includes not only elemental phosphorus but also compounds containing phosphorus. Therefore, phosphorus also includes phosphoric acid. Here, the term "phosphoric acid" is used not only to mean phosphoric acid in the narrow sense, i.e., compounds represented by the chemical formula H3PO4, but also to refer to various phosphates, monohydrogen phosphates, and dihydrogen phosphates in addition to phosphoric acid (H3PO4). Therefore, for example, iron phosphate, unless otherwise specified, refers not only to iron phosphate but also to monohydrogen phosphate and dihydrogen phosphate. Furthermore, there are no restrictions on the valency of the metal contained in the phosphate; for example, the iron ion in iron phosphate may be divalent or trivalent.

[0009] 1. Compost The compost according to one embodiment of the present invention contains carbide, phosphorus, iron, and ammonia-oxidizing archaea. The compost may further contain water and a binder. The compost may further contain sodium hypochlorite. The compost may further contain sulfur-containing compounds, manganese-containing compounds, boron-containing compounds, fibrous substances, etc. contained in fertilizer auxiliaries. Hereinafter, each of these components will be described.

[0010] 1-1. Carbide The carbide contained in this compost is a porous material having carbon as a main component and pores with a cross-sectional diameter of several nm to several tens of μm. The concentration (composition) of carbide in this compost 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. By containing carbide within the above-described range, a high composition of ammonia-oxidizing archaea described later can be maintained. The specific gravity of the carbide is 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 specific surface area of the carbide is, for example, 100 m 2 / g or more and 900 m 2 / g or less, 100 m 2 / g or more and 800 m 2 / g or less, or 150 m 2 / g or more and 400 m 2 / g or less. The specific surface area is measured using a gas adsorption method exemplified by the mercury intrusion method, BJH method, or HK method.

[0011] 1-2. Phosphorus This compost contains phosphorus at a concentration of 2.0% by weight or more and 5.0% by weight or less as total phosphoric acid (that is, the total amount of phosphorus). At least a part of the phosphorus contained in this compost is contained as divalent or trivalent iron phosphate. As will be described later, in the production of this compost, a mixture containing iron and carbide (iron-containing carbide) is treated with water containing phosphoric acid. Therefore, iron(III) phosphate mainly originates from iron in the iron-containing carbide and water containing phosphoric acid.

[0012] In this compost, a part of the phosphorus other than phosphorus may be present as water-insoluble phosphoric acid. Water-insoluble phosphoric acid is phosphoric acid (citrate-soluble phosphoric acid) that is insoluble in water and soluble in a 2% aqueous citric acid solution. Examples of water-insoluble phosphoric acid include calcium hydrogen phosphate, calcium dihydrogen phosphate, calcium phosphate, magnesium hydrogen phosphate, and magnesium phosphate. The metal ions of these water-insoluble phosphoric acids are derived from carbides and organic fertilizer sources, which are the raw materials of the compost.

[0013] This compost may further contain water-soluble phosphoric acid. Examples of water-soluble phosphoric acid include phosphates such as lithium phosphate, sodium phosphate, potassium phosphate, and ammonium phosphate; hydrogen phosphates such as lithium hydrogen phosphate, sodium hydrogen phosphate, potassium hydrogen phosphate, and ammonium hydrogen phosphate; and dihydrogen phosphates such as lithium dihydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, and ammonium dihydrogen phosphate. The metal ions of these water-soluble phosphoric acids are also derived from carbides and organic fertilizer sources.

[0014] For the quantification of the total amount of phosphorus, i.e., total phosphoric acid, contained in this compost, the ammonium vanadomolybdate spectrophotometric method can be used. For example, a predetermined amount of compost is decomposed using nitric acid or perchloric acid, and then ammonium vanadate (V), hexammonium heptamolybdate, and nitric acid are added. The total phosphoric acid is quantified by measuring the absorption of the resulting phosphovanadomolybdate (e.g., absorption at 420 nm) using an ultraviolet-visible spectrophotometer.

[0015] The concentration of water-soluble phosphoric acid can be determined, for example, using the ammonium vanadomolybdate spectrophotometric method. In this method, for example, water is added to this compost, and a predetermined amount of the water-soluble portion is collected as a sample. Nitric acid (1+1) is added to this sample and heated to hydrolyze non-orthophosphoric acid into orthophosphate ions. Then, ammonium vanadate (V), hexammonium heptamolybdate, and nitric acid are added to produce phosphovanadomolybdate. By measuring the absorption of phosphovanadomolybdate (for example, the absorption at 420 nm) using an ultraviolet-visible spectrophotometer, water-soluble phosphoric acid is quantified.

[0016] 1-3. Iron This compost contains iron at a concentration (composition) of 0.4% by weight or more and 6.0% by weight or less. At least a part of the iron contained in this compost exists as iron phosphate. Also, a part of the other may exist as metallic iron (that is, zero-valent iron), or may exist as iron oxide or iron hydroxide. These iron and iron compounds are mainly components derived from the iron and iron oxide added in the manufacturing process of this compost. For example, metallic iron is due to the added iron existing in the compost without being oxidized. Ferric phosphate (III) is produced when a mixture of carbide and iron (iron-containing carbide) is treated with water containing phosphoric acid. As described later, in the production of this compost, the iron-containing carbide is treated under anaerobic conditions together with an organic fertilizer source, and in this process, ferric phosphate (III) is reduced to give divalent iron ions and phosphate ions. These divalent iron ions are oxidized under subsequent aerobic conditions to produce iron (III) oxide and iron (III) hydroxide. As a result, the compost may contain iron (III) hydroxide in addition to the iron (III) oxide added during production.

[0017] 1-4. Ammonia-oxidizing archaea This compost contains at least one of the ammonia-oxidizing archaeon species, Nitrososphaera viennensis and Nitrosopumilus maritimus. The ratio of ammonia-oxidizing archaeon to the total number of bacteria in this compost is between 0.04% and 0.10%. As shown in the examples, the relatively high proportion of ammonia-oxidizing archaeon significantly suppresses odor generation during the composting process because ammonia is nitrified by the ammonia-oxidizing archaeon, and also effectively suppresses odor generation from the resulting compost. Therefore, even when using organic waste as a raw material, it is possible to provide compost with suppressed odor generation caused by ammonia.

[0018] The total number of bacteria and ammonia-oxidizing archaea in this compost can be measured by performing genome analysis on the compost.

[0019] As mentioned above, this compost contains carbonized material, which is a porous material, and also has a relatively high total phosphate concentration. The porous material and phosphate provide space and nutrients, respectively, that allow ammonia-oxidizing archaea to grow and receive oxygen. As a result, this compost has a high proportion of ammonia-oxidizing archaea, and consequently, the ammonia generated during compost production is rapidly nitrified, suppressing the odor caused by ammonia.

[0020] 1-5. Binder A binder is used in the compost manufacturing process described later to efficiently disperse and integrate char, iron powder, and iron oxide. There are no restrictions on the type of binder, but organic and / or inorganic binders can be used. Examples of organic binders include one or more selected from molasses, waste molasses, starch, dextrin, corn starch, rice bran, polyvinyl alcohol, copolymer of vinyl acetate and ethylene or its saponified form, pulp waste liquid, lignin sulfonate, carboxymethylcellulose, hydroxypropyl methylcellulose, sodium alginate, phenolic resin, and tar pitch. Among these, molasses is inexpensive, contains few harmful components, and has a high solid component content, making it easy to mold the removal material. Examples of inorganic binders include cement, blast furnace slag powder, fly ash, gypsum (calcium sulfate), calcined gypsum obtained by heating and dehydrating gypsum, and sodium silicate.

[0021] 1-6. Oxidizing agents In the manufacturing process of this compost, oxidizing agents such as sodium hypochlorite and sulfuric acid may be added as oxidizing agents for sterilization. Therefore, sodium hypochlorite and sulfuric acid derived from residual oxidizing agents may be contained in this compost. The concentration (composition) of sodium hypochlorite and sulfuric acid in this compost may be, for example, 100 ppm or more and 1% or less.

[0022] 1-7. Other ingredients Examples of sulfur-containing compounds include sulfates of alkali metals and alkaline earth metals. Examples of manganese-containing compounds include manganese salts such as manganese sulfate, manganese nitrate, manganese chloride, manganese carbonate, and manganese borate. Examples of boron-containing compounds include manganese borate as mentioned above, as well as boric acid. The concentrations of these sulfur-containing compounds, manganese-containing compounds, and boron-containing compounds in the compost may be, for example, between 0.01% by weight and 1% by weight. The sulfur-containing compounds, manganese-containing compounds, boron-containing compounds, and fibrous material mainly originate from fertilizer additives.

[0023] As mentioned above, this compost contains a relatively high proportion of ammonia-oxidizing archaeon that nitrify ammonia. Furthermore, it also has a high total phosphorus concentration. For these reasons, this compost can be said to have significantly reduced odor generation and is rich in fertilizer components that contribute to plant growth.

[0024] 2. Method for producing compost The following describes a method for producing this compost according to one embodiment of the present invention. The flow chart of this production method is shown in Figure 1.

[0025] 2-1. Preparation of carbides First, carbonized material is prepared. Specifically, organic matter such as biomass is heated at a low oxygen concentration. Here, biomass is a type of organic matter, consisting of living organisms and their metabolites. Examples of biomass that can be used in the preparation of carbonized material include wood-derived materials. Specifically, this includes plank or columnar timber, thinned wood, pruning waste, construction waste wood, powdered sawdust, and wooden molded products such as particleboard. There are no restrictions on the type of wood; cedar, cypress, or bamboo are also acceptable. Alternatively, agricultural waste such as rice husks, bagasse, corn cobs and leaves, and agricultural by-products such as straw, wheat straw, and hay can also be cited as examples of biomass. Plants that are raw materials for fibers such as hemp, flax, cotton, sisal, abaca, and coconut hair can also be cited as biomass. Alternatively, biomass can also be algae such as seaweed, food waste, or silage obtained from animal manure.

[0026] Specifically, carbonized materials can be obtained by heating organic matter in an inert gas atmosphere such as nitrogen gas or argon gas, an oxygen-free atmosphere, a low-oxygen atmosphere, a reducing atmosphere, or a reduced-pressure atmosphere. When carbonization is carried out in a reduced-pressure atmosphere, 10 2 Pa or more 10 5 Low vacuum state below Pa, 10 -1 Pa or more 10 2 A medium vacuum state below Pa, 10 -5 Pa or more 10 -1 High vacuum conditions below Pa, or 10 -5The process can be carried out under an ultra-high vacuum of Pa or less. When carbonization is performed in a low-oxygen atmosphere, the oxygen concentration can be between 0.01% and 3%, or between 0.1% and 2%. The heating temperature for carbonization should be between 400°C and 1200°C, 500°C and 1100°C, 600°C and 1000°C, or 600°C and 900°C. The heating time should be between 10 minutes and 10 days, or between 10 minutes and 5 hours.

[0027] Carbonization is carried out using internal combustion or external heating carbonization furnaces. Examples of carbonization furnaces include batch-type closed carbonization kilns, continuous rotary kilns, oscillating carbonization furnaces, and screw furnaces. Carbonization of organic matter generates carbonized gas, and carbonized material is produced with pores of various shapes and sizes, formed by a complex mixture of pores due to the structure of the organic matter and pores formed by the desorption of carbonized gas. The carbonized gas mainly contains flammable or reducing gases such as hydrogen, carbon monoxide, methane, propane, and alkanes such as butane. Since the carbonized gas is extracted at high temperatures (700°C to 1300°C), its thermal energy and flammability can be used as an energy source for power generation or hot water supply.

[0028] 2-2. Preparation of iron-containing carbides Next, the carbide and iron powder are mixed to obtain iron-containing carbide. As the iron powder, iron powder that has partially oxidized and contains iron oxide or iron hydroxide on its surface may be used. Furthermore, iron oxide powder may be added at the same time as the iron powder. At this time, a binder or water may also be added. Adding a binder or water prevents the generation of dust caused by the carbide, iron powder, and iron oxide powder, and enables uniform mixing.

[0029] There are no restrictions on the shape of the iron powder or iron oxide powder used in this process. For example, iron powder or iron oxide powder with an average circularity of 50 to 100, 70 to 95, or 80 to 90 may be used. Here, average circularity is one of the parameters that represent the shape of each particle contained in the powder. It is obtained by analyzing images obtained by microscopic observation of the powder, determining the circularity of multiple particles, and averaging these values. For example, the value obtained by dividing the perimeter of the projection surface of each particle in the microscopic image by the perimeter of a circle with an area equal to the area of ​​the projection surface can be used. Alternatively, the value obtained by dividing the area of ​​the projection surface by the area of ​​a circle inscribed in the projection surface may be adopted as the circularity. There are also no restrictions on the average particle size of the iron powder or iron oxide powder. For example, it may be 20 μm to 500 μm or 50 μm to 200 μm. Here, the average particle size of the powder is obtained by analyzing images obtained by microscopic observation of the powder, determining the particle size of multiple particles, and averaging these values. For example, the particle size of each particle can be the diameter of the circle inscribed in the projection plane of each particle in the microscope image, or the length of one side of the square.

[0030] The amount of carbide used in mixing should be selected from the ranges of 20% to 80% by weight, 40% to 80% by weight, or 60% to 80% by weight relative to the total weight of carbide, binder, iron powder, and iron oxide powder. The total amount of iron powder and iron oxide powder should be selected from the ranges of 5% to 35% by weight, 5% to 25% by weight, or 5% to 20% by weight relative to the total weight of carbide, binder, and iron powder. When using both iron powder and iron oxide powder, their weight ratio (iron powder:iron oxide powder) should be selected from, for example, a range of 1:5 to 5:1. The amount of binder should be selected from the ranges of 5% to 50% by weight, 15% to 50% by weight, or 20% to 50% by weight relative to the total weight of carbide, binder, iron powder, and iron oxide powder.

[0031] The resulting iron-containing carbide may be granulated as appropriate and formed into a specific shape. Forming can be done using a granulator. Examples of granulators include compression granulators, extrusion granulators, roll granulators, blade granulators, melt granulators, and spray granulators. For example, the iron-containing carbide may be formed into a pellet shape (for example, a roughly cylindrical shape) using an extrusion granulator.

[0032] The iron-containing carbide may be dried further afterward. Drying is carried out at a temperature selected from the ranges of 30°C to less than 400°C, 50°C to 300°C, or 100°C to 300°C. The humidity during drying may be 20% to 95%, or 50% to 90%. The drying time may also be appropriately selected from the ranges of 1 minute to 1 week, 1 hour to 3 days, or 3 hours to 1 day. The atmosphere during drying may also be air, nitrogen, argon or other noble gases, or a mixture thereof.

[0033] 2-3. Preparation of iron phosphate-containing carbides Iron phosphate-containing carbide is prepared by contacting the iron-containing carbide obtained in the previous steps with water containing phosphate (hereinafter referred to as treated water). Treated water may be prepared by dissolving phosphates such as sodium phosphate or potassium phosphate in water, but water from bodies of water such as rivers, lakes, or the sea may also be used as treated water. For example, a container filled with iron-supported carbide may be placed in a river, lake, or sea, and the iron-containing carbide may be brought into contact with the water in the body of water. As a result, the phosphate contained in the water of rivers, lakes, or the sea reacts with the iron, iron oxide, and / or iron hydroxide contained in the iron-containing carbide, and is adsorbed or supported on the carbide as iron(III) phosphate, which has low solubility in water, and at the same time, organic compounds containing phosphate or phosphorus in the water are removed. In other words, this method not only allows for the preparation of iron phosphate-containing carbide at low cost, but also enables water purification and water quality improvement in various bodies of water simultaneously.

[0034] 2-4. Composting We will continue using iron phosphate-containing carbonized material as one of the raw materials for composting.

[0035] (1) A mixture of iron phosphate-containing carbonized material and an organic fertilizer source. First, the iron phosphate-containing char obtained by the method described above is mixed with an organic fertilizer source. There are no restrictions on the amount of iron phosphate-containing char relative to the organic fertilizer source, but for example, 1% to 40% or 5% to 25% by weight of iron phosphate-containing char should be added to the organic fertilizer source. If the viscosity of the resulting mixture (primary mixture) is high, water may be added to adjust the viscosity. Examples of organic fertilizer sources include easily decomposable organic matter of biological origin, such as animal manure and urine such as cow manure, pig manure, and chicken manure, food waste such as food residues, agricultural waste, kitchen waste, and sludge. To determine whether or not an organic matter is easily decomposable, for example, the amount of carbon dioxide generated after mixing with soil or the content of acid detergent-soluble organic matter (AD-soluble organic matter) can be used as indicators.

[0036] The amount of carbon dioxide generated from an organic fertilizer source can be quantified by adding water to a predetermined amount of sample and soil mixture, starting a culture, and then quantifying the carbon dioxide generated during the culture. The generated carbon dioxide can be collected with an aqueous sodium hydroxide solution, and then barium chloride can be added to precipitate it as barium carbonate. The carbon dioxide can then be quantified by titrating the barium carbonate with hydrochloric acid. For example, if the amount of carbon dioxide generated within 10 days of starting the culture is 200 mg or more, 300 mg or more, or 400 mg or more per gram of dry sample, then this sample can be determined to be easily decomposable organic matter and usable as an organic fertilizer source for producing this compost.

[0037] For the quantitative determination of AD-soluble organic matter, for example, the sample is boiled for 1 hour in an acidic detergent solution (e.g., a solution of 20 g of cetyltrimethylammonium bromide dissolved in 1 L of 0.5 mol / L sulfuric acid) and filtered. The residue is washed, dried, and weighed. Then the residue is ashed and weighed, and the weight difference from before ashing is determined as the amount of acid detergent fiber (ADF). Since AD-soluble organic matter is organic matter other than ADF, the amount of AD-soluble organic matter is calculated by subtracting the weight of ADF and the weight of the residue after ashing from the weight of the sample. If the amount of AD-soluble organic matter obtained in this way is 500 mg or more, 600 mg or more, or 700 mg or more per gram of dried sample, then this sample can be determined to be easily decomposable organic matter and usable as an organic fertilizer source for producing this compost.

[0038] However, in the embodiments of the present invention, the organic fertilizer source is not limited by the indicators or their numerical values ​​described above, and any organic matter that can be decomposed by anaerobic microorganisms can be used as an organic fertilizer source.

[0039] The mixing of iron phosphate-containing char and organic fertilizer source may be carried out in a sealed chamber or in an open space. The primary mixture should have an average diameter of several centimeters to several tens of centimeters, or several centimeters. 3 From several thousand centimeters 3 It is obtained as multiple blocks having a certain volume.

[0040] (2) Fermentation The primary mixture is then subjected to a fermentation process. Specifically, the primary mixture is first exposed to an oxygen-containing atmosphere. This oxygen-containing atmosphere may be ambient air, or an atmosphere containing oxygen and an inert gas such as nitrogen or argon. The fermentation process may be carried out at ambient temperature, or in a temperature-controlled environment within the range of 30°C to 60°C. The duration of the fermentation process can also be set arbitrarily, for example, from 1 to 120 days, 10 to 60 days, or 15 to 30 days. This process exposes the surface of each mass of the primary mixture to aerobic conditions, while the interior is exposed to anaerobic conditions. As a result, aerobic fermentation proceeds on the surface of each mass, while anaerobic fermentation proceeds simultaneously inside. In each mass of the primary mixture, the area where aerobic fermentation proceeds is almost entirely limited to the surface, so anaerobic fermentation proceeds in the majority of the primary mixture.

[0041] Anaerobic fermentation is promoted by the action of anaerobic microorganisms contained in the organic fertilizer source. For this reason, anaerobic microorganisms that promote the decomposition of organic matter may be added to the mixture of iron phosphate-containing carbon and the organic fertilizer source described above. Examples of anaerobic microorganisms include nitrate-reducing bacteria, iron-reducing bacteria, sulfate-reducing bacteria, acid-producing bacteria, acetic acid-producing bacteria, and methane-producing archaea, with iron-reducing bacteria and methane-producing archaea being preferred.

[0042] In this fermentation process, the decomposition of organic matter through anaerobic fermentation creates a reducing environment inside each mass of the primary mixture, resulting in a large negative oxidation-reduction potential (ORP). Therefore, within the primary mixture, trivalent iron phosphate is reduced to divalent iron phosphate. Since divalent iron phosphate has higher solubility in water than trivalent iron phosphate, at least a portion of the iron phosphate dissolves in the water contained in the primary mixture, dissociating into divalent iron ions and phosphate ions. For example, if the trivalent iron phosphate in the iron compound-containing char is FePO4, then divalent iron phosphate Fe3(PO4)2 is produced. Furthermore, since iron phosphate-containing char contains char derived from organic matter such as biomass, it contains many alkali metal and alkaline earth metal ions. Similarly, organic fertilizer sources also contain large amounts of alkali metal and alkaline earth ions. These ions ionically bond with phosphate ions, yielding water-soluble and water-insoluble phosphate. Additionally, proteins in organic fertilizer sources decompose into ammonia, resulting in the production of ammonium phosphate from ammonia, phosphate ions, and water.

[0043] (3) Treatment under aerobic conditions After fermentation, the interior of each mass of the primary mixture is treated under aerobic conditions. Specifically, each mass of the primary mixture is crushed, and its interior is brought into contact with oxygen. Crushing may be carried out in the open air or in an atmosphere containing oxygen and an inert gas such as nitrogen or argon. In this process, divalent iron phosphate is rapidly oxidized by oxygen, giving iron(III) oxide and iron(III) hydroxide. At this time, due to the low solubility of iron(III) oxide in water, the reaction between iron(III) oxide and phosphate can be largely ignored, and the phosphate ions produced in the fermentation process ionically bond with alkali metal ions, alkaline earth ions, or ammonium ions, giving water-soluble phosphate and water-insoluble phosphate. The compost of the present invention is provided with space and nutrients that can supply oxygen and nutrients for the growth of ammonia-oxidizing archaea, respectively, through the porous material and phosphate. Therefore, aerobic conditions can be maintained for a long time, allowing ammonia-oxidizing archaea to grow, the ammonia generated during compost production to be nitrified, and the odor caused by ammonia is suppressed.

[0044] 2-5. Sterilization By following the steps described above, compost according to one embodiment of the present invention can be produced, but sterilization treatment may be carried out thereafter. The sterilization treatment is preferably carried out by treating the compost with an oxidizing agent. The treatment with an oxidizing agent may be carried out, for example, by spraying water containing sodium hypochlorite or sulfuric acid. Alternatively, ultraviolet light may be irradiated onto the compost. Furthermore, the moisture content may be appropriately controlled by evaporating water contained in the organic fertilizer source or separately added water, thereby obtaining compost that is easy to handle.

[0045] As described above, anaerobic fermentation occurring within the primary mixture reduces trivalent iron phosphate to divalent iron phosphate. Divalent iron phosphate dissolves in water, releasing phosphate ions. Meanwhile, ammonia is produced by the decomposition of the organic fertilizer source.

[0046] Under subsequent aerobic conditions, divalent iron ions are oxidized and precipitate as less soluble iron(III) oxide, thus suppressing the trapping of phosphate ions by iron ions. On the other hand, the primary mixture contains alkali metal ions and alkaline earth metal ions derived from organic matter and organic fertilizer sources that are the raw materials for the char. Therefore, phosphate ions released by anaerobic fermentation, and phosphate produced in equilibrium with phosphate ions and water, combine with ammonia, alkali metal ions, and alkaline earth metal ions to produce water-soluble phosphate along with insoluble phosphate. As a result, the resulting compost functions as an excellent source of water-soluble phosphate and can contribute to plant growth as a fast-acting fertilizer.

[0047] In this process, anaerobic fermentation occurs, and the organic fertilizer source produces ammonia. However, the charred material used as the raw material for this compost is a porous material with a large number of pores, providing space for ammonia-oxidizing archaea to proliferate. Furthermore, in the manufacturing process of this compost, phosphate reacts with iron, iron oxide, and / or iron hydroxide contained in the iron-containing charred material to be adsorbed or supported on the charred material as lowly soluble iron(III) phosphate, which is then released as water-soluble or water-insoluble phosphate through subsequent anaerobic fermentation. As a result, ammonia-oxidizing archaea can proliferate using phosphate as a nutrient. Consequently, this compost contains a high proportion of ammonia-oxidizing archaea, allowing their action to function effectively and efficiently nitrify the ammonia produced. This mechanism effectively suppresses odor generation during compost production and reduces odor generation from the compost itself.

[0048] 2-6. Other processes The resulting compost may be used alone as fertilizer, or it may be used after being mixed with a fertilizer additive containing the aforementioned sulfur-containing compounds, manganese-containing compounds, or boron-containing compounds. In this case, the fertilizer additive should be added so that the concentration of the sulfur-containing compounds, manganese-containing compounds, or boron-containing compounds in the compost is, for example, between 0.01% by weight and 1% by weight. Mixing can be done using a mixer, which can be arbitrarily selected from free-fall mixers, forced mixers, Y-branch mixers, agitator mixers, or paddle mixers.

[0049] Furthermore, the obtained compost may be dried and shaped. For shaping, the compost can be processed into any shape, such as pellets, rods, granules, or powder. If necessary, crushing and classification may be performed 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 to 10 mm. Crushing can be done using a crusher, such as a vibratory mill, jet mill, ball mill, roller mill, rod mill, hammer mill, impact mill, rotary mill, pin mill, pin-disc mill, or planetary mill. Crushing the compost using a crusher increases the surface area, which in turn promotes the leaching of water-soluble phosphate into the soil. Classification is performed using a classifier, and either a dry classifier or a wet classifier may be used. Examples of classifiers include airflow classifiers, gravity field classifiers, inertial force field classifiers, and centrifugal force field classifiers.

[0050] The compost produced by the method described above, according to one embodiment of the present invention, is not only rich in phosphorus but also has significantly reduced odor caused by ammonia. Therefore, it can contribute to plant growth as an easy-to-handle compost.

[0051] Here, the main component of compost, carbonized material, can be obtained by carbonizing biomass. In other words, carbonized material is prepared by effectively utilizing biomass derived from plants, which is produced by the fixation of carbon dioxide through photosynthesis. Furthermore, the process of manufacturing compost using this carbonized material can improve the water quality of various water systems, and by spreading this compost on the soil, carbon dioxide fixed by plants can be stored in the ground as carbonized material.

[0052] More specifically, as shown in Figure 2, according to an embodiment of the present invention, biomass is carbonized to prepare char (1), and iron-containing char is further prepared from the char (2). This iron-containing char contributes to water purification when it is converted into iron phosphate-containing char (3), and is converted into compost containing porous char originating from biomass through a series of processes including mixing with an organic fertilizer source, fermentation treatment, and treatment under aerobic conditions (4). This compost is spread on the soil as a fertilizer containing water-soluble and non-water-soluble phosphate and used for plant growth (5). Plants fix carbon dioxide from the atmosphere through photosynthesis, providing food and structural materials, and also produce biomass as a by-product that can be used as raw material for char (6).

[0053] The cycle established by this series of processes from (1) to (6) fixes atmospheric carbon dioxide as organic matter through photosynthesis, and this organic matter is used as food and materials, while biomass is produced as a by-product. The biomass is converted into carbonized material through carbonization and is ultimately spread into the ground as compost. Therefore, it can be said that the compost and its production method according to one embodiment of the present invention contribute to the reduction of atmospheric carbon dioxide by storing atmospheric carbon dioxide as carbon in the ground. [Examples]

[0054] This embodiment describes the production and evaluation of compost according to one embodiment of the present invention.

[0055] 1. Preparation of iron phosphate-containing carbides Irregularly shaped charcoal (waste charcoal from wood biomass gasification power generation), iron powder, iron oxide powder, blast furnace slag fine powder as a binder, and water were added and kneaded at room temperature for 30 minutes to obtain a powder mixture. Next, the obtained powder mixture was put into a granulator and formed into pellets with a diameter of 4 mm and a height of 10 mm. After that, the formed powder mixture was dried (cured) at 20°C for 24 hours to obtain iron-containing carbide.

[0056] The iron content in the iron-containing carbide was determined by extracting iron from the crushed iron-containing carbide according to JIS K 1474, and then measuring the extracted iron content using an inductively coupled plasma atomic emission spectrometer (PerkinElmer Optima 5300 DV). As a result, it was confirmed that the iron-containing carbide contained 10% by weight of iron relative to its total volume.

[0057] The obtained iron-containing carbides were packed into a glass column, and sewage sludge dewatering liquor containing 100 mg / L of phosphoric acid was passed through it at a flow rate of 23 L / day for 12 days. The sewage sludge dewatering liquor used here was the supernatant obtained by centrifuging sludge at a sewage treatment plant in Kanagawa Prefecture. Subsequently, the obtained iron phosphate-containing carbides were dried at room temperature for 24 hours to prepare iron phosphate-containing carbides.

[0058] 2. Fermentation Cow manure was used as the organic fertilizer source. In this example, a primary mixture of the organic fertilizer source and iron phosphate-containing char (weight ratio: organic fertilizer source: iron phosphate-containing char = 1:0.05~1:1) was prepared, and this primary mixture was filled into a plastic bottle (capacity approximately 500L), sealed, and fermented at 60°C for 5 days. During the fermentation process, the primary mixture was stirred once a day.

[0059] On the other hand, in the comparative example, iron phosphate-containing carbon was not used, and the organic fertilizer source was subjected to fermentation treatment under the same conditions as in the example.

[0060] After fermentation, the ammonia contained in the sample was volatilized according to the distillation method of the Fertilizer Test Method (Japan Food and Agricultural Materials Inspection Center) 4.1.2.a. The volatilized ammonia was trapped with a trapping agent (0.25 M sulfuric acid aqueous solution), and the ammonia concentration was measured by back titration of the trapping agent with a 0.1 M sodium hydroxide aqueous solution. The results are shown in Figure 3. As shown in Figure 3, the amount of ammonia generated in the example was less than half that of the comparative example, indicating that the amount of ammonia generated can be significantly reduced by using a carbide on which iron phosphate is adsorbed or supported.

[0061] The samples from the fermented examples and comparative examples were subjected to genomic analysis, and the amount of Nitrosospää wiennensis contained in the samples was measured. The results are shown in Figure 4. As can be seen from Figure 4, the amount of Nitrosospää wiennensis in the example sample was found to be approximately eight times that of the comparative example sample. From this, it can be said that using carbonized material on which iron phosphate is adsorbed or supported promotes the growth of ammonia-oxidizing archaea, and as a result, the amount of ammonia generated during composting is reduced.

[0062] The embodiments described above as examples of the present invention can be combined and implemented as appropriate, insofar as they do not contradict each other. Additions, deletions, or design modifications of components based on these embodiments, made by those skilled in the art, are also included within the scope of the present invention, as long as they retain the essence of the invention.

[0063] Any effects or benefits other than those brought about by the embodiments described above, if they are clear from the description herein or easily predictable to those skilled in the art, are naturally understood to be brought about by the present invention.

Claims

1. A porous material having pores, comprising carbide, phosphorus, iron, and ammonia-oxidizing archaea, The total phosphoric acid concentration is 2.0% by weight or more and 5.0% by weight or less. The concentration of the aforementioned iron is 0.4% by weight or more and 6.0% by weight or less. Compost in which the number of ammonia-oxidizing archaea relative to the total number of bacteria is 0.04% or more and 0.10% or less.

2. The compost according to claim 1, comprising the carbonized material in a concentration of 2% by weight or more and 40% by weight or less.

3. The specific surface area of ​​the carbide is 100 m². ２ / g or more 900m ２ The compost according to claim 1, wherein the amount is less than or equal to / g.

4. The compost according to claim 1, wherein at least a portion of the phosphorus and iron is present as iron phosphate.

5. The compost according to claim 1, wherein the ammonia-oxidizing archaeon comprises at least one of Nitrosospäera wiennensis and Nitrosompyrus maritimus.

6. The compost according to claim 1, further comprising a binder.

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