Organic matter processing apparatus and method for producing fermented organic matter

Abstract

The present invention provides an organic matter processing apparatus and a method for producing fermented organic matter that suppress odor generation and enable efficient fermentation. [Solution] The organic matter processing apparatus is an organic matter processing apparatus for fermenting organic matter with microorganisms, and includes a containment tank having a containment space for containing the organic matter and the microorganisms, and a battery having a negative electrode positioned in contact with the organic matter and a positive electrode positioned in contact with an oxidizing agent supply source.

Description

[Technical Field]

[0001] The present invention relates to an organic matter processing apparatus and a method for producing fermented organic matter. [Background technology]

[0002] To effectively utilize limited resources and create a prosperous society, solutions to many social problems, such as preventing global warming and ensuring a stable energy supply, are being considered. Among these social problems, waste management has become one of the most important issues to address in recent years. Organic waste, including food waste, agricultural and marine products, and livestock excrement, amounts to over 200 million tons annually. Burial requires vast land, and incineration incurs enormous disposal costs. By properly processing organic waste, the environmental burden caused by incineration and landfill can be reduced, and it can be reused as a useful resource such as compost.

[0003] Fermentation is widely used as one method of recycling organic waste. Fermentation involves the decomposition of organic matter by the action of microorganisms, converting it into stable humus, and various forms exist, including composting, methane fermentation, and lactic acid fermentation. Composting, in particular, is a method of turning organic matter into compost using aerobic microorganisms, and because it can be carried out with relatively simple equipment, it is widely used from household to industrial applications.

[0004] Household composting systems are used to ferment and decompose organic waste such as food scraps indoors or outdoors, and to reuse the resulting products for gardening or home vegetable gardens. Such composting systems can reduce organic waste. Household composting systems are generally equipped with exhaust structures, stirring mechanisms, and heat retention structures to promote fermentation and suppress the generation of odors and pests.

[0005] In recent years, microbial fuel cells (Microbial Fuel Cells) have attracted attention in the field of new renewable energy as a technology that generates electricity using oxidation-reduction reactions by microorganisms. Microbial fuel cells can produce electricity through metabolic processes using wastewater, plant residues, and human waste. Early microbial battery technologies had low power output per unit area, making commercialization difficult. However, in recent years, technological advancements have led to the development of battery technologies with higher power output. Furthermore, unlike existing fuel cells, microbial fuel cells do not require the use of valuable resources such as hydrogen and rare earth elements, which are difficult to manage. As an alternative to the expected depletion of fossil fuels and the climate change crisis, microbial fuel cells are considered one solution.

[0006] Patent Document 1 proposes a power generation device comprising: a reaction section for performing an electrode reaction; a reducing substance supply means for supplying a reducing substance to the anode side of the reaction section; and a cathode-treated substance introduction means for introducing a cathode-treated product, which has undergone processing on the cathode side of the reaction section, to the anode side, wherein the reducing substance supply means supplies products generated by anaerobic treatment. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2024-120751 [Overview of the project] [Problems that the invention aims to solve]

[0008] Incidentally, one of the problems in the fermentation process of organic matter is the generation of odors caused by decomposition products. Such odors inevitably occur as fermentation progresses. While it is possible to carry out the fermentation process in a sealed container, it is difficult to completely prevent odors from leaking out of the container when adding or removing organic matter. In particular, in the production of compost, excess moisture generated during fermentation is a component that should be removed, and since moisture is removed by exhaust, it is inevitable that odors will leak to the outside.

[0009] Furthermore, fermentation by microorganisms generally takes time, although this varies depending on the type of organic matter, temperature environment, and microbial activity. Naturally, a shorter fermentation time is preferable, and there is a demand for organic matter processing equipment that can efficiently perform fermentation.

[0010] Therefore, the object of the present invention is to provide an organic matter processing apparatus and a method for producing fermented organic matter that suppresses the generation of odors and enables efficient fermentation. [Means for solving the problem]

[0011] As a result of diligent research to achieve the above objective, the inventors of the present invention have found that by appropriately incorporating power generation using an organic matter battery into an organic matter fermentation apparatus, odors during the fermentation process of organic matter can be reduced. Furthermore, they have found that the fermentation process of organic matter is accelerated in this case, leading to the present invention.

[0012] The gist of this invention is as follows: [1] An organic matter processing device for fermenting organic matter with microorganisms, A containment tank having a containment space for containing the organic matter and the microorganisms, An organic matter processing apparatus comprising a battery having a negative electrode positioned in contact with the organic matter and a positive electrode positioned in contact with an oxidizing agent supply source. [2] The redox potential based on the standard hydrogen electrode at 25°C of the material constituting the negative electrode is smaller than the redox potential based on the standard hydrogen electrode at 25°C of the material constituting the positive electrode, the organic matter treatment apparatus according to [1]. [3] The negative electrode includes one or more metals selected from the group consisting of magnesium, lithium, potassium, aluminum, zinc, calcium, iron, manganese, and silicon and / or one or more alloys thereof, the organic matter treatment apparatus according to [1]. [4] The positive electrode includes a porous material, the organic matter treatment apparatus according to [1]. [5] The positive electrode includes a carbon material, the organic matter treatment apparatus according to [1]. [6] The microorganism includes electroactive microorganisms, the organic matter treatment apparatus according to [1]. [7] The electroactive microorganisms include one or more selected from sporomusa ovata, shewanella oneidensis, shewanella putrefaciens, geobacter sulfurreducens, and Aeromonas hydrophila, the organic matter treatment apparatus according to [6]. [8] It has an exhaust part for discharging the gas present in the accommodation space, the organic matter treatment apparatus according to [1]. [9] It is a composting apparatus, the organic matter treatment apparatus according to [1].

[10] It is a household composting apparatus, the organic matter treatment apparatus according to [1].

[11] Using the organic matter treatment apparatus according to any one of [1] to

[10] , while fermenting organic matter by microorganisms, bringing a negative electrode into contact with the organic matter and generating electricity by a battery, a method for producing fermented organic matter.

Effects of the Invention

[0013] As described above, it is possible to provide an organic matter treatment apparatus and a method for producing fermented organic matter in which the generation of odors is suppressed and fermentation can be carried out efficiently.

Brief Description of the Drawings

[0014] [Figure 1] Figure 1 is an external view of the organic matter treatment apparatus according to the present embodiment. [Figure 2] Figure 2 is an x-x cross-sectional view of the organic matter treatment apparatus shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram for explaining the power generation mode of the microbial fuel cell included in the organic matter treatment apparatus shown in Figure 1. [Figure 4] Figure 4 is a schematic diagram for explaining the power generation mode of the microbial fuel cell included in the organic matter treatment apparatus shown in Figure 1. [Figure 5] Figure 5 is a block diagram for explaining the connection state of the microbial fuel cell included in the organic matter treatment apparatus shown in Figure 1.

Embodiments for Carrying out the Invention

[0015] Hereinafter, preferred embodiments of the organic matter treatment apparatus and the method for producing fermented organic matter according to the present invention will be described in detail while referring to the drawings.

[0016] <1. Organic Matter Treatment Apparatus> First, the organic matter treatment apparatus according to a preferred embodiment of the present invention will be described. Figure 1 is an external view of the organic matter treatment apparatus according to the present embodiment, Figure 2 is an x-x cross-sectional view of the organic matter treatment apparatus shown in Figure 1, Figures 3 and 4 are schematic diagrams for explaining the power generation mode of the microbial fuel cell included in the organic matter treatment apparatus shown in Figure 1, and Figure 5 is a block diagram for explaining the connection state of the microbial fuel cell included in the organic matter treatment apparatus shown in Figure 1. In the figures, the size of each member is emphasized appropriately for ease of explanation, and the ratio and size of each actual member are not shown. Also, in each figure, for ease of explanation, the display of members that do not require explanation is omitted.

[0017] The organic matter processing device 1 shown in Figure 1 is a household composting device (household composting device). The organic matter processing device 1 is used to produce compost by fermenting organic matter 100 generated in the home, such as food waste. Examples of such organic matter 100 include fresh foods such as vegetables, fruits, meat, and fish; processed foods; food waste such as vegetable scraps, fruit scraps, rice bran, rice husks, tea leaves, coffee grounds, and leftover tea leaves; food waste such as leftover food; gardening, craft, and DIY waste such as fallen leaves, grass clippings, weeds, pruning waste, branches, flowers, stems, and wood; and paper waste such as copy paper and magazines.

[0018] The organic matter processing apparatus 1 shown in Figure 1 has a housing 10 and an openable / closable lid member 20, and processes organic matter 100 in a processing tank 11 formed inside the housing 10. As shown in Figures 1 to 3, and especially in Figure 2, the organic matter processing apparatus 1 mainly includes a housing 10, a lid member 20, a stirring device 30, an exhaust unit 40, a battery 50, an internal circuit 60, and a temperature control device.

[0019] The housing 10 is a housing that houses each component and member of the organic matter processing apparatus 1. The housing 10 also includes a processing tank 11. The processing tank 11 is a tank for housing organic matter 100 and for fermenting the organic matter 100. In its longitudinal cross-section, the processing tank 11 has a rounded bottom 12 side corresponding to the range of motion of the rotating agitator 30, with vertical walls 14A and 14B formed continuously from the bottom 12 and an opening 13 provided at the top, giving the longitudinal cross-section a U shape.

[0020] Furthermore, end side wall portions 15A and 15B, which have a shape corresponding to the vertical cross-section, are provided so as to sandwich the wall portions 14A and 14B and the bottom portion 12 that form a U-shaped cross-section.The wall portions 14A and 14B, the end side wall portions 15A and 15B and the bottom portion 12 form a containment space 16 for processing organic matter 100.

[0021] Furthermore, guide lines 17 are marked on the wall sections 14A and 14B and the end side wall sections 15A and 15B at a certain height from the bottom section 12. When using the organic matter processing device 1, organic matter 100 can be added up to the height of the guide line 17.

[0022] Furthermore, an opening 141 is provided at the top of the wall section 14B, which communicates with the exhaust section 40, described later. In addition, a mesh filter 18 is placed in the opening 141. Gases in the containment space 16, such as air or water vapor, can move to the exhaust section 40 through the opening 141. In this case, the filter 18 prevents solid matter from moving to the exhaust section 40.

[0023] The lid member 20 is connected to the housing 10 so as to be openable and closable by a hinge (not shown). The lid member 20 includes an inner lid 21. When the lid member 20 is closed, the inner lid 21 can seal the opening 13 of the processing tank 11 in a liquid-tight and airtight manner. This prevents odors generated during the fermentation of organic matter 100 from the processing tank 11 from unintentionally leaking out of the organic matter processing apparatus 1. Furthermore, by sealing the opening 13 of the processing tank 11 with the inner lid 21, temperature control during the fermentation process of organic matter 100 is facilitated.

[0024] The stirring device 30 is capable of stirring the organic matter 100. The stirring device 30 includes a rotating shaft 31, stirring rods 32, 33 and stirring blades 34 connected to the rotating shaft 31, and a drive device. The rotating shaft 31 is supported by the end side walls 15A and 15B near the lower center of the processing tank 11 and is arranged parallel to the walls 14A, 14B and the bottom 12. The rotating shaft 31 is also configured to be rotatable by being connected to a drive device (not shown).

[0025] The stirring rod 32, stirring blade 34, and stirring rod 33 are attached to the rotating shaft 31 at equal intervals in this order, from the end side wall 15A to the end side wall 15B. When the rotating shaft 31 is rotated by the drive device, the stirring rods 32, stirring blade 34, and stirring rod 33 also rotate, stirring the organic matter 100.

[0026] The exhaust section 40 exhausts the gas from the containment space 16 of the processing tank 11. The exhaust section 40 includes a ventilation passage 41, a deodorizing section 43, an exhaust port 45, and an exhaust fan 47. The ventilation passage 41 is a tubular member that guides the gas from the processing tank 11 to the exhaust port 45. One end of the ventilation passage 41 has a ventilation port 411 facing the opening 141, thereby connecting the ventilation passage 41 and the processing tank 11. A space 413 is also formed in the middle of the ventilation passage 41. The space 413 is a gas flow path, while also being formed to accommodate the deodorizing section 43. Multiple openings 415 facing the exhaust port 45 are also provided at the other end of the ventilation passage 41, thereby connecting the ventilation passage 41 and the exhaust port 45.

[0027] The deodorizing section 43 is a cartridge component composed of a deodorizing material, such as activated carbon. The deodorizing section 43 is located in the middle of the ventilation passage 41, and therefore the exhaust from the treatment tank 11 passes through the deodorizing section 43. This removes at least a portion of the odor from the exhaust. The exhaust port 45 is an opening for discharging the exhaust that has passed through the ventilation passage 41 to the outside of the organic matter treatment device 1. An exhaust fan 47 is located in the middle of the exhaust port 45. The exhaust fan 47 creates negative pressure in the ventilation passage 41, and the exhaust is discharged from the exhaust port 45.

[0028] The battery 50 is housed in the processing tank 11 and generates electricity using the organic matter 100 undergoing fermentation. The battery 50 includes a negative electrode (anode) 51, a positive electrode (cathode) 53, and wiring 55. As shown in Figures 3 and 4, the negative electrode 51 and the positive electrode 53 are connected via wiring 55 and an internal circuit 60 of the device.

[0029] The negative electrode 51 is a component that functions as an anode. Specifically, the negative electrode 51 receives electrons (e) generated by the decomposition of organic matter 100 by electroactive microorganisms 200. - The electrons are collected and transferred to the positive electrode 53 side via the wiring 55.

[0030] At the negative electrode 51, a reaction represented by, for example, the following reaction equation (1) occurs, generating electrons from organic acids such as acetic acid. CH3COO- +2H2O → 2CO2+7H + +8e - (1) (Corresponding reduction potential E°' = -0.284V vs. SHE, pH 7)

[0031] The negative electrode 51 is a plate-shaped member. In this embodiment, the negative electrode 51 is attached to the lower side of the end side wall portion 15A, specifically, so that the upper end of the negative electrode 51 is positioned below the guideline 17, so that it is in contact with the organic material 100. As a result, when the organic material 100 is introduced, the negative electrode 51 is embedded in the organic material 100, so that the organic material 100 makes more reliable contact with the negative electrode 51.

[0032] Furthermore, it is preferable that the oxidation-reduction potential of the material constituting the negative electrode 51, based on the standard hydrogen electrode reference (SHE) at 25°C, is smaller than the oxidation-reduction potential of the material constituting the positive electrode 53, based on the standard hydrogen electrode reference at 25°C. This ensures that even if no electrons are generated from the organic acid, electrons are generated when the material constituting the negative electrode 51 dissolves in the fermented product containing the organic matter 100, resulting in power generation. More preferably, the oxidation-reduction potential of the material constituting the negative electrode 51, based on the standard hydrogen electrode reference (SHE) at 25°C, is smaller than the oxidation-reduction potential of the material constituting the positive electrode 53, for example, by 2.0V or more, more preferably by 3.5V or more, and particularly preferably by 4.0V or more.

[0033] The material constituting the negative electrode 51 is not particularly limited as long as it can recover electrons and transfer them to the positive electrode, but for example, it may include one or more metals and / or one or more alloys selected from the group consisting of magnesium (-2.37V), lithium (-3.04V), potassium (-2.93V), aluminum (-1.66V), zinc (-0.76V), calcium (-2.87V), iron (-0.44V), manganese (-1.19V), and silicon (-0.7 to -1.2V). The voltages in parentheses are the standard reduction potentials based on a standard hydrogen electrode at 25°C.

[0034] Among the above, magnesium, calcium, and potassium are preferable because they contribute to the increase in voltage during power generation and act as nutrients in the compost produced even when dissolved in 100 of the organic matter.

[0035] The positive electrode 53 is a member that functions as a cathode. Specifically, the positive electrode 53 is a reaction field that reacts the electrons transferred from the negative electrode 51 with an oxidant present in the vicinity. Usually, the oxidant used in the positive electrode 53 is oxygen in the air 19 present above the organic matter 100 in the accommodation space 16. Then, together with hydrogen ions or water molecules in the organic matter 100, oxygen undergoes the following reduction reaction.

[0036] First, when the organic matter 100 is fermenting in an acidic environment, the reaction represented by the following reaction formula (2) mainly occurs. O2+4H + +4e - → 2H2O (2) (1.229V vs SHE)

[0037] Note that the reactions represented by the following reaction formulas (3) and (4) also occur as side reactions. O2+2H + +2e - → H2O2(3) (0.695V vs SHE) H2O2+2H + +2e - → 2H2O (4) (1.776V vs SHE)

[0038] Next, when the organic matter 100 is fermenting in an alkaline environment, the reaction represented by the following reaction formula (5) mainly occurs. O2+2H2O+4e - → 4OH - (5) (0.401V vs SHE)

[0039] Note that the reactions represented by the following reaction formulas (6) and (7) also occur as side reactions. O2+H2O+2e- → HO2 - +OH - (6) (-0.076V vs SHE) HO2 - +H2O+2e - → 3OH - (7) (0.878V vs SHE)

[0040] Furthermore, if the amount of oxygen in the air 19 decreases due to power generation, manganese dioxide, iron oxide, sulfate ions, nitrate ions, etc. present in the organic matter 100 act as oxidizing agents and are reduced.

[0041] The positive electrode 53 includes a plate-shaped member. In this embodiment, the positive electrode 53 is mounted so as to be in contact with the organic matter 100, specifically so as to be in contact with the organic matter 100 and the air 19 above the organic matter 100 at the end side wall portion 15B. In other words, the upper end of the positive electrode 53 is positioned above the guideline 17 and the support portion is positioned below the guideline 17. As a result, when the organic matter 100 is introduced, the positive electrode 53 comes into contact with air containing oxygen and with the organic matter 100 containing water or hydrogen ions, and the power generation reaction occurs favorably.

[0042] The material constituting the positive electrode 53 is not particularly limited as long as it is conductive, but it is preferable that it includes a porous material. The porous material diffuses water, hydrogen ions present in the organic matter 100 and oxygen present in the air, allowing the reaction on the positive electrode 53 to occur efficiently.

[0043] Examples of such porous materials include carbon materials. Examples of carbon materials include biomass-derived carbon materials such as charcoal and bamboo charcoal, carbon cloth, carbon felt, carbon paper, graphite, amorphous carbon, carbon nanotubes, graphene, and activated carbon. One of these can be used alone or in combination of two or more. Among the above, biomass-derived carbon materials are readily available and can exhibit sufficient performance as the positive electrode 53.

[0044] Furthermore, a catalyst may be supported on the surface of the porous material. Examples of such catalysts include platinum, palladium, streaks, platinum-cobalt alloy, platinum-iron alloy, platinum-nickel alloy, iron-nitrogen-carbon catalyst, cobalt-nitrogen-carbon catalyst, manganese-nitrogen-carbon catalyst, iron-cobalt alloy, iron-manganese alloy, manganese dioxide, cobalt oxide, iron oxide, nickel oxide, and the like.

[0045] The internal circuit 60 is an electrical circuit within the organic matter processing apparatus 1. As shown in Figure 5, the internal circuit 60 includes a boost circuit 61, a storage battery 63, an internal load 65, and an external output unit 67. The electricity generated in the battery 50 is boosted in the boost circuit 61 and supplied to each part of the internal circuit 60.

[0046] The storage battery 63 is a secondary battery such as a lithium-ion battery. The internal load 65 is a power-consuming component such as a microcontroller for controlling the temperature control device or the organic matter processing device 1, which will be described later. The internal load 65 is driven using electricity from the battery 50 supplied from the boost circuit 61, electricity supplied from the storage battery 63, or electricity supplied from the external power supply 300. The external output unit 67 is, for example, a USB terminal or a wireless power supply device. External devices can be electrically connected to the external output unit 67 and receive power from the organic matter processing device 1.

[0047] A temperature control device (not shown) controls the temperature of the organic matter 100 in the processing tank 11. The temperature control device includes, for example, a thermometer and a heater. When the temperature of the organic matter 100 measured by the thermometer is below a predetermined level, the heater activates to heat the organic matter 100. A thermostat may be used instead of a thermometer.

[0048] <2. Method for producing fermented organic matter> Next, a method for producing fermented organic matter according to a preferred embodiment of the present invention will be described together with a method for using the organic matter processing apparatus according to the present invention. The method for producing fermented organic matter according to the present invention involves using the organic matter processing apparatus according to the present invention to ferment organic matter with microorganisms while simultaneously generating electricity using a battery by bringing a negative electrode into contact with the organic matter. The method for producing fermented organic matter according to this embodiment will be described below with reference to an example using the organic matter processing apparatus 1 described above, but the present invention is not limited thereto.

[0049] First, organic matter 100 is put into the treatment tank 11 of the organic matter treatment device 1. Examples of such organic matter 100 include fresh foods such as vegetables, fruits, meat, and fish; processed foods; food processing residues such as vegetable scraps, fruit scraps, rice bran, rice husks, tea leaves, coffee grounds, and tea leaves; food waste such as food scraps (leftovers); gardening, craft, and DIY waste such as fallen leaves, grass clippings, weeds, pruning waste, branches, flowers, stems, and wood; and paper waste such as copy paper and magazines.

[0050] Furthermore, the organic matter 100 may also contain organic matter that serves as a carbon source, in addition to the organic matter derived from the waste mentioned above. Examples of such organic matter that serves as a carbon source include woody resources such as wood flour, wood chips, bark, bamboo flour, and cork flour; agricultural waste such as rice husks, rice straw, wheat straw, peanut shells, coffee bean shells, sugarcane bagasse, coco peat, hemp, cotton, and mushroom cultivation substrate residues; and paper waste such as newspaper scraps, cardboard scraps, and paper pulp residues. Generally, the organic matter used in compost production is often food waste and has a high nitrogen content. In this case, ammonia odor is likely to be generated. Also, food waste has a high moisture content, making it difficult to ensure aeration during fermentation. The carbon source mentioned above improves the C / N ratio (carbon / nitrogen ratio) of the organic matter 100 by adding the carbon source, and also adjusts the moisture content of the organic matter 100 to ensure aeration.

[0051] Next, a fermentation accelerator may be mixed with the organic matter 100 as needed. The fermentation accelerator may include, for example, microorganisms that promote the fermentation of the organic matter 100, actinomycetes such as actinomycetes, filamentous fungi, fungi such as white rot fungi, yeasts such as Saccharomyces, etc.

[0052] Examples of microorganisms include aerobic bacteria such as those of the genus Bacillus, lactic acid bacteria (genus Lactobacillus), photosynthetic bacteria (genus Rhodopseudomonas), other microorganisms used in fermentation (e.g., genus Corynebacterium, Saccharomyces cerevisiae, Escherichia coli, etc.), and electroactive microorganisms. Among the above, it is preferable that the fermentation accelerator contains electroactive microorganisms as microorganisms.

[0053] Electroactive microorganisms (EAMs) are microorganisms that can exchange electrons directly or indirectly with surrounding microbial communities or conductive electrode surfaces, and act as biocatalysts that connect biochemical phenomena associated with metabolism with electrical phenomena such as electrons flowing through external circuits. Technologies using EAMs are collectively called bioelectrochemical systems (BES). The inventors believe that this technology using EAMs can be applied to a variety of fields, such as electrical energy recovery through the decomposition of organic matter, chemical synthesis (microbial electrosynthesis), and hydrogen production. In this embodiment, the inventors attempted to generate electricity during the fermentation of organic matter using these electroactive microorganisms and found that the odor of the fermented material was reduced and fermentation was promoted.

[0054] Although the principle is not entirely clear, the inventors speculate as follows: First, during power generation, the organic acids in the organic matter 100 are oxidized and consumed, resulting in a decrease in the organic acid content and thus suppression of odor generation. Furthermore, in the power generation reaction, hydrogen ions are consumed, causing the organic acids and acids such as hydrogen sulfide in the organic matter to become anions or be neutralized by other cations, making volatilization difficult. As a result, it is thought that the odor caused by the acids is reduced.

[0055] Furthermore, it is conceivable that the organic acids in the organic matter 100 are consumed by the power generated by the battery 50, thereby suppressing the acidification of the organic matter 100, preventing a decrease in microbial activity, and consequently promoting fermentation. Moreover, in the biochemical reaction pathway by microorganisms involving oxidation-reduction reactions with electron transfer, it is conceivable that some pathways can be short-circuited by the power generated by the battery 50, thereby promoting the decomposition of the organic matter 100.

[0056] Furthermore, waste materials containing a large amount of organic matter, such as food waste, leave behind persistent organic pollutants (POPs) during fermentation. POPs often lack electron donors or acceptors for the redox reaction in fermentation, making decomposition by microbial fermentation alone difficult. However, in this embodiment, it is believed that the battery reaction caused by the battery 50 allows for the transfer of electrons on the surface of the positive electrode 53 or negative electrode 51, enabling decomposition by redox reaction of such persistent organic pollutants.

[0057] Electroactive microorganisms are not particularly limited as long as they possess electroactivity, but examples include Geobacter species such as Geobacter sulfurreducens and Geobacter metallireducens, and sulfur cycle-related microorganisms such as Shewanella oneidensis, Shewanella putrefaciens, Aeromonas hydrophila, Sporomusa ovata, and Desulfocapsa. Geobacter species are bacteria that oxidize organic acids such as acetic acid and directly transfer electrons to electrodes. Shewanella oneidensis can transfer electrons to electrodes and metal oxides via an electron shuttle mechanism mediated by outer membrane cytochromes and flavins. Sulfur cycle-related microorganisms are involved in the disproportionation and reduction of sulfur compounds. Specifically, Desulfocapsa species can oxidize sulfur oxides to sulfate ions. Among those mentioned above, the electroactive microorganisms preferably include one or more selected from Sporomusa ovata, Shewanella oneidensis, Shewanella putrefaciens, Geobacter sulfurreducens, and Aeromonas hydrophila.

[0058] Such fermentation accelerators can be used as MP (Microorganisms Polyphenols) activators (aggregates of microorganisms), leaf mold, activated sludge, digestate residue, compost, and bokashi. Additionally, water may be added to the treatment tank 11 to adjust the moisture content as needed.

[0059] After adding organic matter 100 and, if necessary, a fermentation accelerator and water to the treatment tank 11, the treatment tank 11 is sealed with a lid member 20, and the tank is heated by a temperature control device, thereby initiating fermentation by microorganisms.

[0060] The temperature of the organic matter 100 during the fermentation process is not particularly limited, but is, for example, 20°C to 80°C, preferably 30°C to 50°C. Furthermore, the fermentation process is not particularly limited, but is, for example, 2 hours or more and 9 hours or less, preferably 4 hours or more and 6.5 hours or less.

[0061] During the fermentation process, the organic matter 100 is gently stirred by the rotation of the stirring device 30. For example, it is preferable to stir the organic matter 100 with the stirring device 30 for the first 5 to 30 minutes, preferably 5 to 15 minutes, of the fermentation process, and then leave the organic matter 100 to stand. Furthermore, during the fermentation process, carbon dioxide and water vapor are generated, increasing the amount of gas in the treatment tank 11. Also, the generation of water during fermentation increases the moisture content of the organic matter 100, reducing the fermentation efficiency. Therefore, it is necessary to exhaust the waste through the exhaust unit 40 to remove excess moisture and gas.

[0062] Specifically, when the exhaust fan 47 is activated, negative pressure is created in the ventilation passage 41, and air 19 from the storage space 16 inside the processing tank 11 is introduced. The introduced air 19 passes through the deodorizing section 43 and is discharged as exhaust from the exhaust port 45.

[0063] Conventionally, exhaust gases discharged from organic matter treatment devices in this manner were accompanied by odors, and even with the use of deodorizers such as activated carbon, the odors could not be sufficiently removed. However, in this embodiment, such odors are suppressed by the operation of the battery 50.

[0064] In parallel with the fermentation process described above, power is generated by the battery 50. In this embodiment, power generation by the battery 50 occurs spontaneously during the fermentation process. The power generation by the battery 50 will be explained below with reference to Figures 3 and 4.

[0065] First, as the organic matter 100 ferments, it decomposes to produce organic acids such as acetic acid. Next, the electroactive microorganisms 200 become active and, for example, through a reaction represented by reaction equation (1) above, the organic acids are decomposed to generate electrons and hydrogen ions. The generated electrons are collected at the negative electrode 51 and transferred to the positive electrode 53 side via the wiring 55 and the internal circuit 60 of the device.

[0066] Here, if the oxidation-reduction potential of the material constituting the negative electrode 51, based on the standard hydrogen electrode reference (SHE) at 25°C, is smaller than the oxidation-reduction potential of the material constituting the positive electrode 53, electrons are generated when the material constituting the negative electrode 51 dissolves in the fermented product containing organic matter 100, and as a result, power generation is possible. In such a case, even if the microbial fuel cell using organic matter 100 does not function, the battery 50 functions complementaryly, and power generation is possible. That is, when power generation is performed by electroactive microorganisms 200, the battery 50 functions as a microbial fuel cell, and when the battery 50 does not function as a microbial fuel cell, it functions as a primary battery. The microbial fuel cell using organic matter 100 and the primary battery formed by the dissolution of the material constituting the negative electrode 51 are complementary, but basically, the one with the smaller reduction potential in their oxidation-reduction reactions is preferred.

[0067] At the positive electrode 53, electrons transferred from the negative electrode 51 react with an oxidizing agent present nearby. Typically, the oxidizing agent used at the positive electrode 53 is oxygen in the air 19 present above the organic matter 100 in the containment space 16. When the organic matter 100 is fermenting in an acidic environment, the reactions represented by reaction equations (2) to (4) described above occur, as shown in Figure 3, producing water from oxygen, hydrogen ions, and electrons. On the other hand, when the organic matter 100 is fermenting in an alkaline environment, the reactions represented by reaction equations (5) to (7) described above occur, as shown in Figure 4, producing hydroxide ions from oxygen, water, and electrons. Furthermore, if the amount of oxygen in the air 19 becomes insufficient due to power generation, manganese dioxide, iron oxide, sulfate ions, nitrate ions, etc., present in the organic matter 100 act as oxidizing agents and are reduced.

[0068] As described above, fermentation of organic matter 100 by microorganisms is carried out simultaneously with power generation by the battery 50. The electricity generated is transferred to the internal circuit 60 of the device, boosted by the boost circuit 61, and then used for the operation and control of various parts of the organic matter processing device 1, such as the temperature control device (consumed by the internal load 65 of the device), or stored in the storage battery 63, or used to supply power to external devices from the external output unit 67.

[0069] As described above, compost as an organic fermented product is obtained from the organic matter 100 that has undergone fermentation treatment. In this process, the following effects are obtained in this embodiment.

[0070] First, in this embodiment, odor generation is suppressed during the fermentation process, and odor generation in the resulting organic fermented product is also suppressed. This is thought to be because hydrogen ions are consumed during power generation by the battery 50, making it difficult for the organic acids in the organic matter 100 to volatilize. Furthermore, since the organic acids in the organic matter 100 are oxidized and consumed during power generation, the organic acid content decreases. In addition, while hydrogen sulfide may be generated if anaerobic fermentation occurs, the generation of hydrogen sulfide is also suppressed because the power generation by the battery 50 involves a reaction that oxidizes the organic matter 100.

[0071] Next, in this embodiment, the fermentation of the organic matter 100 is promoted by power generation by the battery 50. This is thought to be because the organic acids in the organic matter 100 are consumed by the power generation by the battery 50, thereby suppressing the acidification of the organic matter 100 and preventing a decrease in the activity of microorganisms. Furthermore, in the biochemical reaction pathway by microorganisms that involves oxidation-reduction reactions with electron transfer, it is thought that some pathways can be short-circuited by power generation by the battery 50, thereby promoting the decomposition of the organic matter 100. Moreover, persistent organic pollutants that tend to be generated during fermentation are also easily decomposed by assisting in the transfer of electrons during power generation by the battery 50.

[0072] Furthermore, in this embodiment, electricity can be obtained by generating power with the battery 50. The generated electricity can be used to operate the organic matter processing device 1 itself or external devices. The inventors have successfully generated electricity simultaneously with composting in a household composting device using a magnesium negative electrode and a bamboo charcoal positive electrode, and have actually obtained electricity with a maximum voltage of 3.4V.

[0073] Although the present invention has been described in detail above based on preferred embodiments, the present invention is not limited thereto, and each component can be replaced with any component that can perform a similar function, or any component can be added.

[0074] For example, in the embodiments described above, the negative electrode 51 and the positive electrode 53 were described as being attached to the inner wall (end side wall portion 15A, end side wall portion 15B) of the processing tank 11, but the present invention is not limited thereto. For example, the negative electrode can be positioned at any position so as to be in contact with organic matter. The positive electrode can also be positioned at any position so as to be in contact with the oxidizing agent.

[0075] Furthermore, although the embodiments described above assumed that the negative electrode 51 and positive electrode 53 were plate-shaped members, the present invention is not limited thereto. For example, the negative electrode and positive electrode may be in any form, such as rod-shaped or powder-shaped.

[0076] For example, in the embodiments described above, the organic matter treatment device 1 was described as a household composting device, but the present invention is not limited thereto. For example, the organic matter treatment device according to the present invention can be a composting device such as a commercial composting device (compost plant), a livestock waste treatment device, a biogas plant such as a methane fermentation device, an anaerobic digester, an aerobic biological treatment device, a wastewater treatment device, and the like. [Explanation of Symbols]

[0077] 1. Organic matter treatment device 10 cabinets 11 Processing tank 20 Lid member 30 Stirring device 40 Exhaust section 50 batteries 51 Negative electrode 53 Positive electrode 60 Device internal circuit

Claims

1. An organic matter processing device for fermenting organic matter using microorganisms, A containment tank having a containment space for containing the organic matter and the microorganisms, for fermenting the organic matter, The battery includes a negative electrode positioned in contact with the organic material and a positive electrode positioned in contact with an oxidizing agent source, The negative electrode comprises one or more metals selected from the group consisting of magnesium, potassium, and calcium, and / or one or more alloys thereof. A composting device, an organic matter processing device.

2. The organic material processing apparatus according to claim 1, wherein the oxidation-reduction potential of the material constituting the negative electrode, based on a standard hydrogen electrode reference at 25°C, is smaller than the oxidation-reduction potential of the material constituting the positive electrode, based on a standard hydrogen electrode reference at 25°C.

3. The organic material processing apparatus according to claim 1, wherein the positive electrode includes a porous material.

4. The organic material processing apparatus according to claim 1, wherein the positive electrode comprises a carbon material.

5. The organic matter processing apparatus according to claim 1, wherein the microorganisms include electroactive microorganisms.

6. The organic matter processing apparatus according to claim 5, wherein the electroactive microorganism comprises one or more selected from Sporomusa ovata, Shewanella oneidensis, Shewanella putrefaciens, Geobacter sulfurreducens, and Aeromonas hydrophila.

7. The organic matter processing apparatus according to claim 1, further comprising an exhaust unit for discharging gas present in the containment space.

8. The organic matter processing device according to claim 1, which is a household composting device.

9. A method for producing fermented organic matter, comprising using an organic matter processing apparatus according to any one of claims 1 to 8, fermenting organic matter with microorganisms, and generating electricity with a battery by bringing a negative electrode into contact with the organic matter.

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