Device for activating acetic acid generating bacteria

Abstract

To provide a device for activating acetic acid generating bacteria that can effectively use organic waste water as a resource for producing acetic acid.SOLUTION: A device for activating acetic acid generating bacteria (active device 100) includes a treatment tank 110 for storing a fluid comprising organic waste water, a carrier 130 accommodated in the treatment tank 110 for carrying an anaerobic microorganism, a water purification pump 140 for pumping up treatment water stored in the lower part of the treatment tank 110 and circulating the same to the treatment tank 110, hydrogen supply means 160 for supplying hydrogen to the treatment tank 110, and a nozzle 120 for spraying the treatment water in the treatment tank 110.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus for activating acetic acid-producing bacteria to produce acetic acid by activating acetic acid-producing bacteria. [Background technology]

[0002] Conventionally, methods for producing acetic acid using anaerobic microorganisms have been known. For example, Patent Document 1 discloses a method for producing acetic acid using anaerobic microorganisms capable of producing acetic acid, including "(1) a step of contacting a heated hydrocarbon compound with oxygen and water vapor to produce a gas containing hydrogen and carbon dioxide, (2) a step of contacting the hydrogen and carbon dioxide produced in (1) with anaerobic microorganisms capable of producing acetic acid under conditions suitable for the production of acetic acid, and (3) a step of recovering the acetic acid produced by the anaerobic microorganisms in step (2)."

[0003] Patent Document 2 also discloses a method for producing acetic acid using anaerobic microorganisms capable of producing acetic acid, comprising "(1) a step of culturing the anaerobic microorganisms in the presence of a gaseous carbon compound at a temperature 8 to 12° C. lower than the culture temperature at which the optimal specific growth rate is exhibited, and (2) a step of recovering the acetic acid produced by the anaerobic microorganisms in step (1)." Patent Document 2 also discloses that in step (1), the culture is performed in the presence of a mixed gas containing a gaseous carbon compound and / or hydrogen, and that the gaseous carbon compound is a compound selected from carbon monoxide and carbon dioxide.

[0004] According to the methods for producing acetic acid using anaerobic microorganisms capable of producing acetic acid described in Patent Documents 1 and 2, "technologies for industrially producing acetic acid using anaerobic microbial metabolism are provided, which can meet the demand for acetic acid as an industrial raw material." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-036149 A [Patent Document 1] JP 2011-223888 A Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, in recent years, methods for effectively utilizing organic wastewater as a resource, rather than simply treating it as wastewater, have been studied. Therefore, the inventors thought that if organic wastewater could be used as a culture medium for acetic acid-producing bacteria to produce acetic acid, it would be possible to effectively utilize organic wastewater.

[0007] In view of the above problems, the present invention aims to provide an apparatus for activating acetic acid-producing bacteria that can effectively utilize organic wastewater as a resource for producing acetic acid. [Means for solving the problem]

[0008] In order to solve the above problems, a typical configuration of the acetic acid producing bacteria activation device of the present invention is characterized by comprising a treatment tank for storing a fluid which is organic wastewater, a carrier housed in the treatment tank and supporting anaerobic microorganisms, a purified water pump for pumping the treated water stored in the lower part of the treatment tank and circulating it to the treatment tank, a hydrogen supply means for supplying hydrogen to the treatment tank, and a nozzle for spraying the treated water into the treatment tank.

[0009] The acetic acid-producing bacteria activation device is provided with an ejector disposed in the path of the purified water pump, the hydrogen supply means is connected to the treatment tank via the ejector, the ejector converts hydrogen supplied from the hydrogen supply means into fine bubbles and mixes them with the treatment water, and the nozzle is connected to the downstream side of the ejector and sprays the treatment water mixed with hydrogen into the treatment tank.

[0010] The hydrogen supply means preferably includes a solar panel that generates electricity using sunlight and a water electrolysis tank, and hydrogen is produced by electrolyzing water using the electricity generated by the solar panel.

[0011] The acetic acid producing bacteria activation device may be provided with a carbon dioxide supplying means for supplying carbon dioxide to the treatment tank.

[0012] The acetic acid-producing bacteria activation device is provided with an ejector disposed in the path of the purified water pump, and the carbon dioxide supplying means is connected to the treatment tank via the ejector. The ejector converts the carbon dioxide supplied from the carbon dioxide supplying means into fine bubbles and mixes them with the treatment water. The nozzle is connected to the downstream side of the ejector and sprays the treatment water mixed with carbon dioxide into the treatment tank. Effect of the Invention

[0013] According to the present invention, it is possible to provide an apparatus for activating acetic acid-producing bacteria that can effectively utilize organic wastewater as a resource for producing acetic acid. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of an acetic acid producing bacteria activation device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating an embodiment of a carrier. [Diagram 3] FIG. 1 is a diagram illustrating a coconut shell fiber mat, which is a biodegradable fiber mat. [Figure 4] FIG. 2 is a schematic diagram illustrating the mechanism of action of homoacetic acid bacteria retained on a carrier. [Diagram 5] FIG. 1 is a diagram illustrating an acetic acid production test using homoacetic acid bacteria. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific values ​​shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present invention are not shown.

[0016] Fig. 1 is a schematic diagram of an acetic acid producing bacteria activation apparatus according to this embodiment (hereinafter, referred to as an activation apparatus 100). As illustrated in Fig. 1, the activation apparatus 100 of this embodiment includes a treatment tank 110 that stores and circulates a fluid that is organic wastewater.

[0017] A storage tank (not shown) that stores organic wastewater that has been pretreated, such as by removing sediment, is connected to treatment tank 110 via supply pipe 102, and the pretreated fluid is supplied via supply pipe 102. Supply pipe 102 is connected to nozzle 120 disposed on the upper part of treatment tank 110, and the fluid supplied to treatment tank 110 is sprayed into treatment tank 110 by nozzle 120. Nozzle 120 also communicates with the downstream side of ejector 150, which will be described later, and sprays treated water (circulated water) that has passed through ejector 150 into treatment tank 110.

[0018] 1, a carrier 130 carrying anaerobic microorganisms is accommodated inside the treatment tank 110. As described above, the fluid sprayed from the nozzle 120 comes into contact with the carrier 130 as it flows down inside the treatment tank 110. This causes a contact reaction with the anaerobic microorganisms (not shown) carried by the carrier 130, and the organic matter contained in the fluid is decomposed.

[0019] The carrier 130 is filled in the treatment tank 110 and carries anaerobic microorganisms. In this embodiment, biodegradable fibers are used for the carrier 130. With this configuration, the carrier 130 itself is slowly biodegraded, so the amount of waste can be reduced. As an example of the decomposition speed, while organic substances contained in the treated water are decomposed in a cycle of several days, the carrier 130 is decomposed in about a year. In addition, the carrier 130 can be reused after use as fertilizer.

[0020] Therefore, according to the carrier 130 of this embodiment, it is not necessary to dispose of it as industrial waste after it has been used to treat organic wastewater, and it is possible to reduce industrial waste and, in turn, the burden on the environment. When the carrier 130 is biodegraded in the treatment tank 110 and loses weight, it is sufficient to replenish the carrier 130.

[0021] In addition, foam materials (such as foamed polyurethane) have often been used in conventional carriers, but foam materials tend to be clogged due to the accumulation of solid matter exceeding the diameter of the micropores (for example, 0.3 to 2.0 mm) on the surface or the increase in slime (biofilm), which makes it easy for surface flow to occur. In contrast, by using a fibrous material instead of a foam material, solid matter can be taken inside and contacted with microorganisms, making it possible to suppress the occurrence of surface flow. In addition, the use of a fibrous material promotes the supply of gas (hydrogen or carbon dioxide in this embodiment) to the inside of the carrier 130, making it possible to improve the efficiency of decomposition treatment of organic matter in organic wastewater by anaerobic microorganisms.

[0022] As the biodegradable fiber, coconut shell can be preferably used. Coconut shell is widely distributed, so it is inexpensive and easy to obtain. In addition, coconut shell has a certain degree of rigidity, so it has the advantage that it is difficult to deform even when stacked vertically (for example, 1m).

[0023] Furthermore, the coconut shell carrier 130 has the function of decomposing organic matter contained in organic wastewater using the microorganisms carried thereon, as in the conventional method, and is also capable of filtering and capturing suspended solids in the organic wastewater due to its high water permeability. Note that the biodegradable fiber is not limited to coconut shell, and other materials such as wood, sugar cane, and rice husks can also be used.

[0024] The carrier 130 is preferably in the form of a brush with the tips of the biodegradable fibers facing the surface. "The tips facing the surface" means that the cut surface of the tips of the bristles is on the surface of the carrier 130. This ensures that even if slime forms on the surface of the carrier 130, the tips (ends) of the biodegradable fibers will protrude from the slime. This ensures a sufficient contact area between the organic wastewater and the anaerobic microorganisms, making it possible to maintain favorable treatment efficiency.

[0025] Fig. 2 is a diagram for explaining an embodiment of the carrier 130. Fig. 3 is a diagram illustrating a coconut shell fiber mat, which is a mat of biodegradable fibers. The coconut shell fiber mat shown in Fig. 3 is formed by molding rope-shaped coconut fibers into a sheet by needle punching.

[0026] A carrier 130a according to a first embodiment shown in Fig. 2(a) is a cylinder made of biodegradable fibers. A carrier 130b according to a second embodiment shown in Fig. 2(b) is formed by stacking a plurality of disks 132 made of biodegradable fibers in a cylindrical shape and connecting the disks 132 with biodegradable fasteners 134.

[0027] The disks 132 of the carrier 130a in Example 1 and the carrier 130b in Example 2 may be formed by punching out a biodegradable fiber mat (a coconut shell fiber mat shown in FIG. 3) with a tool such as a cutter (not shown). As a result, the surfaces of the carriers 130a and 130b (strictly speaking, the disks 132) are left uncut, so that the tips of the biodegradable fibers are brush-like with their ends facing the surface, and the above-mentioned effects can be obtained without carrying out any special surface processing.

[0028] Specifically, the carrier 130a of Example 1 can be manufactured in one punching (step) by using a thick mat, whereas the disk 132 of the carrier 130b of Example 2 can be easily punched by using a thin mat.

[0029] The carrier 130c of Example 3 shown in Fig. 2(c) is constructed by spirally winding a biodegradable fiber mat to form a cylinder 136, and fastening the outer surface of the cylinder 136 with a biodegradable band 138. With this construction, the same effect as above can be obtained. However, in the carrier 130c of Example 3, the proportion of fiber bristles facing the surface of the carrier is low.

[0030] In this embodiment, homoacetic bacteria are used as the acetic acid producing bacteria (anaerobic microorganisms) carried by the carrier 130. Specifically, examples of mesophilic homoacetic bacteria include bacteria classified into the genus Acetogenium, Acetbacterium, Clostridium, Butyribacterium, Sporomusa, and Ruminococcus. Examples of thermophilic homoacetic bacteria include bacteria classified into the genus Moorella. The action of homoacetic bacteria will be described in detail later.

[0031] In this embodiment, the carrier 130 is made of biodegradable fibers, but the present invention is not limited to this. If necessary, the carrier 130 may be made of a sponge carrier, a sound-absorbing mat, or a plastic carrier, which are conventionally used in the DHS method.

[0032] Referring again to Figure 1, the fluid sprayed from nozzles 120 in treatment tank 110 passes through carrier 130 and is stored in the lower part of treatment tank 110 as treated water. The stored treated water is pumped up through purified water path 142 by purified water pump 140 at a predetermined timing. The pumped treated water is circulated to treatment tank 110 through circulation path 146.

[0033] An ejector 150 that generates fine bubbles is disposed in the path of the purified water pump 140, i.e., the purified water path 142. The ejector 150 is connected to a hydrogen supply means 160 via a hydrogen supply path 162, and converts hydrogen supplied from the hydrogen supply means 160 into fine bubbles and mixes them with the treated water. As a result, fine hydrogen bubbles (microbubbles) are supplied to the treated water pumped up from the lower part of the treatment tank 110 by the purified water pump 140 as it passes through the ejector 150. The treated water that has passed through the ejector 150 is sprayed into the treatment tank 110 by a nozzle 120 that is in communication with the downstream side of the ejector 150.

[0034] That is, in this embodiment, the hydrogen supply means 160 is connected to the treatment tank 110 via the ejector 150. Hydrogen is supplied to the treatment tank 110 by spraying the treatment water mixed with finely bubbled hydrogen in the ejector 150 into the treatment tank 110.

[0035] 4 is a schematic diagram illustrating the mechanism of action of the homoacetobacterium held in the carrier 130. Since the carrier 130 is made of coconut shell fiber, which has high water permeability, when the treated water containing finely bubbled hydrogen passes through the carrier 130 as shown in FIG.

[0036] Furthermore, when the treated water passes through the carrier 130, the homoacetic acid bacteria held in the carrier 130 are activated using the finely bubbled hydrogen in the treated water as an energy source, decomposing the dissolved substances (organic matter) in the treated water and producing homoacetic acid (see the homoacetic acid production formula in FIG. 4). The produced homoacetic acid is separated from the treated water and then taken out as an acetic acid concentrate from an acetic acid outlet 144 connected to the bottom of the treatment tank 110. Therefore, the activation device 100 of this embodiment makes it possible to effectively use organic wastewater as a resource for producing acetic acid.

[0037] In particular, in this embodiment, hydrogen is made into fine bubbles by the ejector 150. Hydrogen is a gas with low solubility in water, but the fine bubbles have a large surface area, so hydrogen is easily dissolved in water, and the hydrogen concentration in the water can be increased. Therefore, the amount of dissolved hydrogen in the water to which the fine bubbles are supplied is increased compared to when hydrogen is simply aerated. Therefore, by spraying the treatment water containing a large amount of hydrogen into the treatment tank 110, hydrogen can be efficiently supplied to the entire treatment tank 110. As a result, the activation of the anaerobic microorganisms supported on the carriers 130 can be promoted throughout the entire treatment tank 110, and the treatment efficiency of the organic wastewater can be further improved.

[0038] In the activation device 100 of this embodiment, the hydrogen supply means 160 is composed of a solar panel 164 that generates electricity using sunlight, and a water electrolysis tank 166. That is, in the hydrogen supply means 160 of this embodiment, hydrogen is produced by electrolyzing water in the electrolysis tank 166 using the electricity generated by the solar panel 164. This makes it possible to reduce the cost required for procuring hydrogen.

[0039] Furthermore, in the activation device 100 of this embodiment, a carbon dioxide supplying means 170 is connected to the ejector 150 via a carbon dioxide supplying path 172. As a result, carbon dioxide is supplied from the carbon dioxide supplying means 170 to the ejector 150, and the ejector 150 turns the supplied carbon dioxide into fine bubbles and mixes them with the treatment water.

[0040] That is, in this embodiment, the carbon dioxide supplying means 170 is connected to the treatment tank 110 via the ejector 150. Then, carbon dioxide is supplied to the treatment tank 110 by spraying the treatment water mixed with finely bubbled carbon dioxide in the ejector 150 into the treatment tank 110.

[0041] By supplying carbon dioxide as described above, the anaerobic state in the activation device 100 can be suitably maintained. Carbon dioxide can also be used as a carbon source when the homoacetic bacteria held in the carrier 130 produce acetic acid. Note that the carbon dioxide supplying means 170 can be, for example, a carbon dioxide cylinder, and other known means for supplying a gas containing a large amount of carbon dioxide may also be used.

[0042] In this embodiment, the hydrogen supply means 160 and the carbon dioxide supply means 170 are connected to the treatment tank 110 via the ejector 150, but the present invention is not limited to this. When the ejector 150 is not used, the hydrogen supply means 160 and the carbon dioxide supply means 170 may be directly connected to the treatment tank 110 to supply hydrogen and carbon dioxide. Alternatively, one of the hydrogen supply means 160 and the carbon dioxide supply means 170 may be connected to the treatment tank 110 via the ejector 150, and the other may be directly connected to the treatment tank 110.

[0043] 5 is a diagram for explaining an acetic acid production test by homoacetobacteria. In the acetic acid production test, sludge collected from an anaerobic digester at a test site was used as treated water, the test temperature was constant at 25°C, and treated water was supplied to the treatment tank 110 in a circulating manner. The ratio of carbon dioxide and hydrogen supplied to the ejector 150 was 1:4.

[0044] In the acetic acid production test, the soluble COD concentration (s-COD) and volatile fatty acid concentration (VFA) were also measured. s-COD indicates the amount of oxidized substances dissolved in the treated liquid, and in this experiment it increases due to the accumulation of VFAs and other substances. The measurement sample was prepared by filtering the treated liquid with a nylon syringe filter. s-COD was measured using a spectrophotometer (DR3900, HACH, USA) with potassium dichromate as an oxidizing agent on the filtered measurement sample.

[0045] VFA indicates a state in which acid-producing bacteria and homoacetic bacteria are highly active. The VFAs in this experiment were acetic acid, propionic acid, n-butyric acid, iso-butyric acid, n-valeric acid, and iso-valeric acid. The measurement samples were those used for s-COD measurement, and were derivatized by adding hydrochloric acid (2.4 mol L) before analysis. A gas chromatograph with FID (GC-2014, Shimadzu, Japan) was used for the analysis. Pure nitrogen gas of 99.9995 vol.% was used as the carrier gas.

[0046] As shown in Figure 4, s-COD rose to 11,284 mg / L on Day 7, then gradually decreased, but increased to 8,000 mg / L on Day 41. After that, s-COD never fell below 5,000 mg / L and continued to increase to 26,638 mg / L on Day 70. The measured values ​​of VFA were generally plotted on s-COD.

[0047] Analysis by gas chromatography revealed that acetic acid accounted for over 87% of VFA, and that the increase in s-COD was caused by an increase in VFA and the accumulation of acetic acid. VFA showed roughly the same values ​​as s-COD, and the amount of acetic acid produced is proportional to s-COD. From this, it is believed that 1g / L of acetic acid was produced per day in the acetic acid production test shown in Figure 4.

[0048] A further feature of the activation device 100 of this embodiment is that the connecting path 148 connecting the treatment tank 110 and the purified water pump 140 is provided with a water level sensor 180 that detects the water level of the treated water stored in the lower part of the treatment tank 110, and a control unit 182 that controls the operation of the purified water pump 140.

[0049] The control unit 182 operates the purified water pump 140 when the water level of the treated water detected by the purified water pump 140 reaches or exceeds a predetermined value. With this configuration, when a certain amount of treated water accumulates in the lower part of the treatment tank 110, a part of the treated water pumped up by the purified water pump 140 is discharged to the outside. This makes it possible to preferably prevent the treated water from overflowing from the treatment tank 110 due to the treatment tank 110 becoming full.

[0050] Furthermore, if the carrier 130 becomes clogged with slime or the like, the fluid (treated water) sprayed from the nozzle 120 flows down to the bottom of the treatment tank 110 without being captured by the carrier 130. This reduces the efficiency of the contact reaction between the fluid and the carrier 130, and increases the rate at which the water level rises. In such a case, the water level sensor 180 operates the purified water pump 140 according to the water level, thereby increasing the number of times the purified water pump 140 is started, and the amount of hydrogen and carbon dioxide supplied to the carrier 130 can be increased, making it possible to increase the efficiency of the contact reaction between the fluid and the carrier 130.

[0051] On the other hand, the water level sensor 180 stops the purified water pump 140 when the water level of the treated water falls below a predetermined value. With this configuration, when the amount of treated water inside the treatment tank 110 becomes extremely low, the discharge of the treated water to an external facility (not shown) is stopped, and the treated water is stored in the treatment tank 110. This makes it possible to suppress drying of the carrier 130 and prevent the death of the anaerobic microorganisms supported on the carrier 130.

[0052] Furthermore, the activation device 100 of this embodiment includes a lid 190 that serves as the top surface of the treatment tank 110, and the nozzle 120 sprays the treated water toward the underside of the lid 190. This allows the treated water to be sprayed more evenly and efficiently over a wider area than when the nozzle 120 simply sprays the treated water (downward). This promotes the activation of anaerobic microorganisms, and makes it possible to further increase the efficiency of acetic acid production and the efficiency of organic wastewater treatment.

[0053] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above-described embodiment. It is clear that a person skilled in the art can think of various modifications or alterations within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. [Industrial Applicability]

[0054] The present invention can be used as an acetic acid producing bacteria activation device for activating acetic acid producing bacteria to produce acetic acid. [Explanation of symbols]

[0055] 100...activation device, 102...supply pipe, 110...treatment tank, 120...nozzle, 130...carrier, 130a...carrier, 130b...carrier, 130c...carrier, 132...disk, 134...tool, 136...cylinder, 138...band, 140...purified water pump, 142...purified water path, 144...acetic acid outlet, 146...circulation path, 148...connection path, 150...ejector, 160...hydrogen supply means, 162...hydrogen supply path, 164...solar panel, 166...electrolysis tank, 170...carbon dioxide supply means, 172...carbon dioxide supply path, 180...water level sensor, 182...control unit, 190...lid

Claims

1. a treatment tank for storing the organic wastewater fluid; A carrier that is contained in the treatment tank and supports anaerobic microorganisms; A water purification pump that pumps up the treated water stored in the lower part of the treatment tank and circulates it to the treatment tank; A hydrogen supply means for supplying hydrogen to the treatment tank; A nozzle for spraying the treated water into the treatment tank; An apparatus for activating acetic acid-producing bacteria, comprising:

2. An ejector is provided in the path of the purified water pump, the hydrogen supply means is connected to the treatment tank via the ejector, The ejector converts hydrogen supplied from the hydrogen supply means into fine bubbles and mixes the bubbles with the treated water, 2. The acetic acid producing bacteria activation device according to claim 1, wherein the nozzle is connected to the downstream side of the ejector and sprays the treatment water mixed with the hydrogen into the treatment tank.

3. The hydrogen supply means is A solar panel that generates electricity from sunlight, a water electrolysis tank; 3. The acetic acid-producing bacteria activation device according to claim 1, wherein the hydrogen is produced by electrolyzing water using the electricity generated by the solar panel.

4. 2. The apparatus for activating acetic acid-producing bacteria according to claim 1, further comprising a carbon dioxide supplying means for supplying carbon dioxide to the treatment tank.

5. An ejector is provided in the path of the purified water pump, the carbon dioxide supply means is connected to the treatment tank via the ejector, The ejector converts the carbon dioxide supplied from the carbon dioxide supply means into fine bubbles and mixes the bubbles with the treatment water, The acetic acid producing bacteria activation device according to claim 4, characterized in that the nozzle is connected to the downstream side of the ejector and sprays the treatment water mixed with the carbon dioxide into the treatment tank.

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