Fermentation apparatus, liquid fertilizer manufacturing apparatus, and liquid fertilizer manufacturing method

Abstract

To propose a fermentation apparatus which increases concentration of a liquid fertilizer and enables manufacture of a liquid fertilizer that is easily transported.SOLUTION: In a fermentation apparatus 1 having a fermentation tank 2, a solid-liquid separator 5 and a concentrator 7, the fermentation tank 2 ferments organic matter by anaerobic digestion and produces a digested liquid. The concentrator 7 has a permeable membrane 10. The permeable membrane 10 has properties that allow water to permeate while preventing the permeation of at least one of nitrogen, phosphoric acid, or potassium. An individual component is removed from the digested liquid taken from the fermentation tank 2 through the solid-liquid separator 5, and furthermore, the moisture content of the digested liquid is reduced and concentrated through the permeable membrane 10 of the concentrator 7.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fermentation apparatus for producing liquid fertilizer from digestive liquid obtained by fermenting food waste, animal waste, etc. The present invention also relates to a liquid fertilizer producing apparatus and a liquid fertilizer producing method. [Background technology]

[0002] As one method for effectively utilizing food waste and sewage, it has been proposed to generate methane gas through anaerobic digestion and then collect and utilize the methane gas. That is, food waste and sewage are used as raw materials and fermented by anaerobic bacteria to generate methane gas, which can be used for power generation, etc. In addition, a method has been proposed in which the digestive fluid obtained as a by-product from this process can be used as liquid fertilizer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-19207 A Summary of the Invention [Problem to be solved by the invention]

[0004] The method disclosed in Patent Document 1 makes it possible to produce liquid fertilizer. However, the produced liquid fertilizer has a high water content and is expensive to transport. The present invention focuses on the above-mentioned problems of the prior art, and aims to propose a fermentation apparatus capable of increasing the concentration of liquid fertilizer and producing liquid fertilizer that is easy to transport. Another object of the present invention is to provide a liquid fertilizer production apparatus and a liquid fertilizer production method that can solve the same problems. [Means for solving the problem]

[0005] An embodiment for solving the above-mentioned problems is a fermentation apparatus having a fermenter, a solid-liquid separation device, and a concentration device, in which the fermenter produces a digestive liquid by fermenting organic matter using an anaerobic digestion method, and the concentration device has a permeable membrane that is permeable to water and has a property of being difficult to permeate at least any one of nitrogen, phosphate, and potassium, and is characterized in that solid components are removed from the digestive liquid taken out of the fermenter by the solid-liquid separation device, and further the water content of the digestive liquid is reduced and concentrated by the permeable membrane of the concentration device.

[0006] The fermentation apparatus of this embodiment has a fermentation tank, and can obtain a digestive liquid by anaerobic digestion of organic matter in the fermentation tank. The digested liquid removed from the fermenter contains a large amount of solid matter. The fermentation apparatus of this embodiment has a solid-liquid separation device, which can remove the solid matter from the obtained digested liquid. The fermentation apparatus of this embodiment also includes a concentrating device. The concentrating device has a permeable membrane that is permeable to water and has a property of being difficult to permeate at least any one of nitrogen, phosphate, and potassium. The fermentation apparatus of this embodiment can reduce and concentrate the water content of the digestive liquid by using the permeable membrane.

[0007] In the above aspect, the permeable membrane is desirably made of polytetrafluoroethylene resin.

[0008] In each of the above-mentioned aspects, it is desirable that the concentration device has a water tank section and the permeable membrane, the inside of the water tank section is divided into a plurality of spaces by a wall including the permeable membrane, one space is an introduction side space and the space adjacent to the wall is a discharge side space, and the digestive liquid in the introduction side space is introduced to move water to the discharge side space to concentrate the digestive liquid in the introduction side space.

[0009] According to this embodiment, the digestive fluid can be efficiently concentrated.

[0010] In each of the above-mentioned aspects, it is preferable that the concentration device has a water tank section and a membrane separator, the membrane separator has an internal space and an opening that connects the internal space to the outside, the permeable membrane is attached to the opening, the membrane separator is disposed in the water tank section, there is a gap between the membrane separator and an inner wall of the water tank section, and the digestion liquid in the introduction side space is introduced into either the gap or the internal space to move water to the other side and concentrate the digestion liquid.

[0011] According to this embodiment, the digestive fluid can be efficiently concentrated.

[0012] In the above aspect, it is desirable to have an agitation means, and to use the agitation means to agitate the digestive fluid in at least the space on the side of the water tank portion into which the digestive fluid is introduced.

[0013] In the fermentation apparatus of this embodiment, at least the space in the water tank where the digestive liquid is introduced is agitated. Therefore, the corresponding space on the upstream side of the permeable membrane is agitated and the surface of the permeable membrane on the introduction side is wiped. As a result, clogging of the permeable membrane is eliminated.

[0014] Another aspect for solving a similar problem is a liquid fertilizer production apparatus that produces liquid fertilizer using digestive liquid extracted from a fermentation tank as a raw material, the apparatus comprising a solid-liquid separation device and a concentration device, the concentration device having a permeable membrane that is permeable to water and has properties that make it difficult for at least one of nitrogen, phosphate, and potassium to permeate, the solid-liquid separation device removing solid components from the digestive liquid, and the permeable membrane of the concentration device further reducing the water content of the digestive liquid and concentrating it.

[0015] The liquid fertilizer producing apparatus of this embodiment produces liquid fertilizer using the digestive fluid removed from the fermentation tank as a raw material. The digested liquid removed from the fermenter contains a large amount of solid matter. The fermentation apparatus of this embodiment has a solid-liquid separation device, which can remove the solid matter from the obtained digested liquid. The fermentation apparatus of this embodiment also includes a concentrating device. The concentrating device has a permeable membrane that is permeable to water and has a property of being difficult to permeate at least any one of nitrogen, phosphate, and potassium. The fermentation apparatus of this embodiment can reduce and concentrate the water content of the digestive liquid by using the permeable membrane.

[0016] Another aspect for solving a similar problem is a liquid fertilizer production method comprising a digestive liquid production step of obtaining a digestive liquid by fermenting organic matter by anaerobic digestion, a solids removal step of removing solids from the digestive liquid, and a concentration step of concentrating the digestive liquid from which the solids have been removed, wherein the concentration step involves introducing the digestive liquid into a space partitioned on at least one side by a permeable membrane, the permeable membrane having the property of allowing water to pass through but being difficult to pass at least any of nitrogen, phosphate, and potassium, and wherein the water content of the digestive liquid is reduced by discharging the water in the digestive liquid through the permeable membrane, thereby concentrating the digestive liquid.

[0017] According to this embodiment, digestive juice can be produced efficiently. The aspect for solving the above problem is as follows: In a fermentation apparatus having a fermentation tank, a solid-liquid separation device, and a concentration device, The fermenter is a device for fermenting organic matter by anaerobic digestion to produce digestive liquid, The concentrating device has a permeable membrane, the permeable membrane having a property of permeating water and being difficult to permeate at least any one of nitrogen, phosphoric acid, and potassium; A fermentation apparatus that removes solid components from the digested liquid taken out from the fermenter by the solid-liquid separation device, and further reduces and concentrates the water content of the digested liquid by the permeable membrane of the concentration device, The concentrating device comprises: A water tank section, and A membrane separator disposed in the water tank portion, An internal space and an opening communicating the internal space with the outside; and The permeable membrane is included. A membrane separator is provided. An annular outer space is provided between the membrane separator and the water tank portion, The membrane separator has the permeable membrane attached to the opening other than the upper surface of the frame member, The digestive liquid is introduced into the external space, and the water content of the digestive liquid is moved to the internal space, thereby concentrating the digestive liquid in the external space; and The fermentation apparatus has an agitation means for agitating the digestive fluid in at least the exterior space of the water tank section. The stirring means has an aeration device, and the digestive fluid in the exterior space can be stirred and brought into contact with air by air bubbles generated by the aeration device. The permeable membrane may be made of polytetrafluoroethylene resin. The aspect for solving the above problem is as follows: A liquid fertilizer production apparatus for producing liquid fertilizer using digestive liquid taken out from a fermentation tank as a raw material, The fermenter, a solid-liquid separator, and a concentrator are provided, The concentrating device has a permeable membrane, and the permeable membrane has a property of permeating water and being difficult to permeate at least any one of nitrogen, phosphoric acid, and potassium; removing solid components from the digestive liquid by the solid-liquid separation device, and further concentrating the digestive liquid by reducing the water content by the permeable membrane of the concentrating device; The fermenter is a device for fermenting organic matter by anaerobic digestion to produce digestive liquid, The concentrating device comprises: A water tank section, and A membrane separator disposed in the water tank portion, An internal space and an opening communicating the internal space with the outside; and The permeable membrane is included. A membrane separator is provided. An annular outer space is provided between the membrane separator and the water tank portion, The membrane separator has the permeable membrane attached to the opening other than the upper surface of the frame member, The digestive liquid is introduced into the external space, and the water content of the digestive liquid is moved to the internal space, thereby concentrating the digestive liquid in the external space; and The liquid fertilizer producing apparatus has an agitation means for agitating the digestive liquid in at least the exterior space of the water tank section. An aspect for solving the above-mentioned problems is a liquid fertilizer production method using such a fermentation apparatus or liquid fertilizer production apparatus. Effect of the Invention

[0018] The liquid fertilizer produced by the fermentation apparatus, the liquid fertilizer production apparatus, and the liquid fertilizer production method of the present invention has a high concentration and is easy to transport. [Brief description of the drawings]

[0019] [Figure 1] FIG. 2 is a system diagram of a fermentation apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view of a concentrator of the embodiment of the present invention of the fermenter of FIG. 1. [Diagram 3] FIG. [Figure 4] FIG. 2 is an exploded perspective view of the inner tank (membrane separator) of the concentration apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The embodiments of the present invention will be described further below. The fermentation apparatus 1 of this embodiment uses food waste and human waste as fermentation raw materials, crushes them, and feeds them into a fermentation tank 2, where they are fermented to produce methane gas. In addition, digestive liquid is produced as a by-product. The fermentation apparatus 1 of the present embodiment is an apparatus that converts digestive fluid, which has conventionally been discarded as a by-product, into liquid fertilizer.

[0021] The fermentation apparatus 1 of this embodiment is composed of a fermenter 2, a receiving tank 3, a solid-liquid separator 5, a separated water tank 6, a concentrator 7, and a water treatment device 8, as shown in FIG. The fermenter 2 is a sealed tank. The fermenter 2 is equipped with a stirrer, a temperature regulator, a level gauge, a temperature sensor, a pressure sensor, and the like (none of which are shown), similar to known fermenters.

[0022] Food waste and sewage are put into the fermentation tank 2, where they are fermented by anaerobic bacteria to produce methane gas (anaerobic digestion method). Digestive juices are also produced as a by-product of fermentation.

[0023] The solid-liquid separator 5 is a known screen or trommel device. The solid-liquid separator 5 has a screen 41 built therein.

[0024] The concentrator 7 utilizes a permeable membrane 10 to concentrate the digestive fluid. As shown in FIG. 2, the concentrator 7 is composed of a water tank section 11 and an aeration device 12. The water tank section 11 has a double structure as shown in Figures 2 and 3. That is, the water tank section 11 has an outer tank (water tank section) 15 and an inner tank (membrane separator) 16. The inner tank 16 is smaller than the outer tank 15. The inner tank 16 has a frame member 20 and a permeable membrane 10 attached to each surface of the frame member 20, as shown in FIG. The frame member 20 has an opening 22 that communicates between an internal space 21 and the outside, and the permeable membrane 10 is attached to the opening 22 .

[0025] The permeable membrane 10 is made of tetrafluoroethylene resin. The permeable membrane 10 has the property of being permeable to water and impermeable to fertilizer components. Specifically, the permeable membrane 10 has the property of being permeable to water and impermeable to at least any one of nitrogen, phosphoric acid, and potassium. In this embodiment, hollow fibers are used as the filtration membrane. Specifically, the permeable membrane 10 is a precision filtration membrane module using Poreflon (registered trademark) manufactured by Sumitomo Electric Industries, Ltd.

[0026] The aeration device 12 is composed of a blower 25 and a porous member 26. The water tank section 11 has an outer tank (water tank section) 15 with a porous member 26 and an inner tank (membrane separator) 16 built in. As shown in FIG. 2, the porous member 26 is disposed at the bottom of the outer tank (water tank portion) 15, below the inner tank 16 (permeable membrane 10). The inner tank (membrane separator) 16 is located in the center of the outer tank (water tank portion) 15. The outer edge of the porous member 26 reaches the outside of the inner tank 16. In this embodiment, the aeration device 12 also functions as an agitation means for agitating the digestive fluid.

[0027] As described above, the inner tank (membrane separator) 16 is located in the center of the outer tank (water tank portion) 15. Therefore, a gap 28 is present between the outer wall of the inner tank (membrane separator) 16 and the inner wall of the outer tank (water tank portion) 15. In this embodiment, a gap 28 between the outer wall of the inner tank (membrane separator) 16 and the inner wall of the outer tank (water tank portion) 15 forms an annular outer space 40 surrounding the outside of the inner tank 16. The concentrator 7 employed in this embodiment has an outer tank (water tank section) 15, and the inside of the outer tank (water tank section) 15 is partitioned into a plurality of spaces by walls including a permeable membrane 10.

[0028] The water treatment device 8 is a device that purifies the digestive fluid by denitrifying, dephosphorizing, and deodorizing it to a level that allows it to be discharged into a river. The structure of the water treatment device 8 is publicly known, so a detailed description thereof will be omitted.

[0029] Next, the relationship between the various components will be described. The fermentation apparatus 1 of this embodiment stores the digestive liquid removed from the fermentation tank 2 in the receiving tank 3, and then flows it in turn to the solid-liquid separation device 5, the separated water tank 6, the concentrating device 7, and the water treatment device 8. For this reason, a pump 30 is provided between the fermentation tank 2 and the receiving tank 3. Similarly, a pump 31 is provided between the receiving tank 3 and the solid-liquid separation device 5, a pump 32 is provided between the separated water tank 6 and the concentrating device 7, and a pump 33 is provided between the concentrating device 7 and the water treatment device 8.

[0030] The pump 32 between the separation tank 6 and the concentrator 7 sucks the digestive fluid from the separation tank 6 and introduces it into the external space 40 of the concentrator 7. A pump 33 is provided between the concentrator 7 and the water treatment device 8 to suck the digestive liquid from the inner tank (membrane separator) 16 of the concentrator 7 and send it to the water treatment device 8 downstream. In this embodiment, the concentrator 7 further includes a pump 35 for extracting digestive fluid from the external space 40 .

[0031] In the fermentation apparatus 1 of this embodiment, a digestive liquid production process is carried out in which organic matter is fermented by anaerobic digestion to obtain a digestive liquid in the fermentation tank 2. The digestive liquid is sent to a solid-liquid separation device 5, which carries out a solid content removal process in which impurities (solid content) 43 are removed from the digestive liquid. Furthermore, a concentration process is carried out in a concentration device 7 in which the digestive liquid from which the solid content has been removed is concentrated.

[0032] The functions of the fermentation apparatus 1 will now be described in detail. The fermentation tank 2 is where organic matter such as food waste is put in, and where the organic matter is decomposed by anaerobic bacteria to produce methane gas, with digestive liquid being produced as a by-product. In this embodiment, the digested liquid accumulated in the fermenter 2 is removed by a pump 30 and stored in a receiving tank 3. The digested liquid wiped off from the fermenter 2 contains a large amount of impurities (solid contents) 43.

[0033] The digested liquid in the receiving tank 3 is then sent to a solid-liquid separator 5 by a pump 31. In the solid-liquid separator 5, the digested liquid is passed through a screen 41 or the like to remove impurities (solids) 43 from the digested liquid, and the purified digested liquid 42 is stored in a separation tank 6.

[0034] Next, the digestive liquid in the separation tank 6 is introduced into the external space 40 of the concentration device 7 by the pump 32. The separation tank 6 has a double structure and is divided into the external space 40 and an internal space 21 separated by an inner tank (membrane separator) 16. The digestive fluid is introduced into the exterior space 40 and gradually moves into the interior space 21 . Here, between the external space 40 and the internal space 21 there is a permeable membrane 10, which has the property of being permeable to water but difficult to permeate at least any of the fertilizer components such as nitrogen, phosphate, potassium, etc. Therefore, the digestive fluid with a low fertilizer content accumulates in the internal space 21. On the other hand, the digestive fluid remaining in the external space 40 has an increased concentration of fertilizer components.

[0035] In the fermentation apparatus 1 of the present embodiment, the pump 35 is used to recover the digestive fluid having a high fertilizer concentration from the exterior space 40 . The digestive fluid collected from the external space 40 is temporarily stored in a storage tank 45 and then packed into a tank (not shown) and transported. The digestive liquid recovered from the exterior space 40 is concentrated and has a high fertilizer concentration, so it has a small volume relative to the fertilizer components and is easy to transport. The digestive fluid collected from the external space 40 is used as fertilizer for fields either as is or after being diluted with water to adjust its concentration.

[0036] In the concentrator 7, the aeration device 12 is constantly driven, increasing the chances of the digested liquid inside coming into contact with air. As a result, the activity of aerobic bacteria becomes more active, and the digestive fluid is purified to a certain extent.

[0037] In the fermentation apparatus 1 of this embodiment, the digestive liquid in the water tank section 11 is agitated by air bubbles generated by the aeration device (agitation means) 12. The digestive liquid in the outside space 40 (introduction side space) is also agitated by air bubbles generated by the aeration device 12. In the concentration device 7 of this embodiment, the inner tank (membrane separator) 16 is located in the center of the outer tank (water tank portion) 15 , and the outer edge of the porous member 26 reaches the outside of the inner tank 16 . Therefore, the porous member 26 of the aeration device 12 is also located below the permeable membrane 10, and the air bubbles released from the porous member 26 pass near the surface of the permeable membrane 10. This causes the digestive fluid to be agitated near the permeable membrane 10, and the movement of the air bubbles and digestive fluid wipes the outside space 40 (introduction space) side of the permeable membrane 10. As a result, clogging of the membrane is suppressed. That is, in this embodiment, the aeration device 12 aerates the external space 40 (introduction side space) of the water tank section 11, and the digestive fluid flows in the external space 40 (introduction side space) side of the permeable membrane 10. As a result, the external space 40 (introduction side space) side of the permeable membrane 10 is wiped with air bubbles and digestive fluid, and clogging is eliminated.

[0038] Meanwhile, the digestive fluid in the internal space 21, which is dilute in fertilizer components, is sent by the pump 33 to the water treatment device 8, where it is highly purified before being discharged into the river.

[0039] The fermentation apparatus 1 described above has a receiving tank 3 and a separating water tank 6, and employs a line configuration for temporarily storing digested liquid. However, the receiving tank 3 and the separating tank 6 are not essential, and the digested liquid may be allowed to flow continuously.

[0040] In the embodiment described above, the digestive liquid in the separation water tank 6 is introduced into the exterior space 40 of the concentration device 7, the water is moved to the interior space 21 side, and the digestive liquid remaining in the exterior space 40 is concentrated. The fermentation apparatus 1 of the present embodiment concentrates the digestive liquid by using the exterior space 40 as an introduction space and the interior space 21 as a discharge space. However, the present invention is not limited to this configuration, and the internal space 21 may be used as an introduction space to introduce the digestive fluid in the separation tank 6, and the external space 40 may be used as a discharge space to concentrate the digestive fluid in the internal space 21.

[0041] In the embodiment described above, the aeration device 12 is also used as the stirring means. However, an agitation device having agitating blades may be provided in the exterior space 40 .

[0042] Of the components described above, the components downstream of the fermenter 2 function as a liquid fertilizer producing device. [Explanation of symbols]

[0043] 1 Fermentation equipment 2 Fermentation tank 3 Receiving tank 5 Solid-liquid separator 6 Separation tank 7 Concentration device 10. Permeable membrane 11 Sink Department 12 Aeration device (stirring means) 15 Outer groove 16 Inner groove 21 Internal space (drainage side space) 22 Opening 40 External side space (introduction side space)

Claims

1. In a fermentation apparatus having a fermentation tank, a solid-liquid separation device, and a concentration device, The fermenter is a device for fermenting organic matter by anaerobic digestion to produce digestive liquid, The concentrating device has a permeable membrane, the permeable membrane having a property of permeating water and being difficult to permeate at least any one of nitrogen, phosphoric acid, and potassium; A fermentation apparatus that removes solid components from the digested liquid taken out of the fermenter by the solid-liquid separation device, and further reduces and concentrates the water content of the digested liquid by the permeable membrane of the concentration device, The concentrating device comprises: A water tank section, and A membrane separator disposed in the water tank portion, An internal space and an opening communicating the internal space with the outside; and The permeable membrane is included. A membrane separator is provided. An annular outer space is provided between the membrane separator and the water tank portion, The membrane separator has the permeable membrane attached to the opening other than the upper surface of the frame member, The digestive liquid is introduced into the external space, and the water content of the digestive liquid is moved to the internal space, thereby concentrating the digestive liquid in the external space; and A fermentation apparatus having an agitation means for agitating the digestive liquid in at least the exterior space of the water tank section.

2. 2. The fermentation apparatus according to claim 1, wherein the stirring means has an aeration device, and the digestive liquid in the external space is stirred and brought into contact with air by air bubbles generated by the aeration device.

3. 3. The fermentation apparatus according to claim 1, wherein the permeable membrane is made of polytetrafluoroethylene resin.

4. A liquid fertilizer production apparatus for producing liquid fertilizer using digestive liquid taken out from a fermentation tank as a raw material, The fermenter, a solid-liquid separator, and a concentrator are provided, The concentrating device has a permeable membrane, and the permeable membrane has a property of permeating water and being difficult to permeate at least any one of nitrogen, phosphoric acid, and potassium; removing solid components from the digestive liquid by the solid-liquid separation device, and further concentrating the digestive liquid by reducing the water content by the permeable membrane of the concentrating device; The fermenter is a device for fermenting organic matter by anaerobic digestion to produce digestive liquid, The concentrating device comprises: A water tank section, and A membrane separator disposed in the water tank portion, An internal space and an opening communicating the internal space with the outside; and The permeable membrane is included. A membrane separator is provided. An annular outer space is provided between the membrane separator and the water tank portion, The membrane separator has the permeable membrane attached to the opening other than the upper surface of the frame member, The digestive liquid is introduced into the external space, and the water content of the digestive liquid is moved to the internal space, thereby concentrating the digestive liquid in the external space; and A liquid fertilizer producing apparatus comprising an agitation means for agitating the digestive liquid in at least the exterior space of the water tank section.

5. 5. The liquid fertilizer producing apparatus according to claim 4, wherein the stirring means has an aeration device, and the digested liquid in the external space is stirred and brought into contact with air by air bubbles generated by the aeration device.

6. A method for producing liquid fertilizer using the fermentation apparatus according to claim 1 or 2, or the liquid fertilizer production apparatus according to claim 4 or 5.

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