JP6944282B2 - Methane fermentation system and monitoring method for methanogens - Google Patents

Description

The present invention relates to a methane fermentation system and a method for monitoring methanogens.

Conventionally, in methane fermentation facilities and the like, it has been widely practiced to generate biogas such as methane gas from biomass raw materials such as organic waste by various fermentation techniques.

For example, in a methane fermentation facility, when methane gas is produced from a biomass raw material, the biomass raw material is reduced in molecular weight and acid is produced by liquefaction, hydrolysis, etc. to produce lower fatty acids and alcohol. Then, by hydrogen production and acetic acid production, hydrogen + carbon dioxide or acetic acid is fermented using a bacterium (methanogen) to generate methane gas. The methane gas and heat generated in this way are recovered.

By the way, in a methane fermentation facility, in order to smoothly start up the facility and recover methane gas as planned, a certain number or more of methanogens responsible for methane fermentation are contained in the fermentation broth of the fermenter. It is important to be present. Therefore, an efficient monitoring method for methanogens is required.

Therefore, as a technique for monitoring methanogens in methane fermentation, the fluorescence intensity of a fluorescent coenzyme (8-hydroxy-5-diazaflavin derivative, hereinafter referred to as fluorescent substance F420) specifically present in methanogens is measured. As a result, techniques for measuring the activity of methanogens are disclosed in, for example, JP-A-1-250041 (Patent Document 1) and JP-A-8-154662 (Patent Document 2).

In the methane-producing bacterium measuring device described in Patent Document 1, a fermenter, a conduit for flowing a subject containing the methane-producing bacterium in the fermenter, and a light source that irradiates the subject with excitation light in a predetermined wavelength range. A video camera that acquires fluorescence in a predetermined wavelength range from the fluorescence emitted by the subject when irradiated with excitation light as a fluorescence image, and image processing of the fluorescence image to eliminate fluorescence based on substances other than methane-producing bacteria. It is provided with an image processing circuit to be used.

In the methane-producing bacterium measuring device, in measuring the fluorescence intensity, the methane-producing bacterium is irradiated with light of 420 nm from a light source to make the fluorescent substance F420 glow pale, and the fluorescence intensity is measured with a video camera. The measured fluorescence intensity data is sent to the image processing circuit.

In this type of methanogen measuring device, the subject containing the methanogen is contained in the fermenter by providing a membrane filter and a washing control device for washing the subject containing the methanogen in advance before irradiating with excitation light. It is said that it is possible to remove fluorescent substances other than methanogens and remove the background of fluorescent images.

Further, the automatic control system for the methane fermenter described in Patent Document 2 is connected to the methane fermenter, the sampling line that is connected to the methane fermenter and sends out the methanogen, and the sampling line, and is connected to the sampling line to pretreat the methanogen. A pretreatment device for performing the above, a fluorescence spectrophotometer connected to the pretreatment device, and a data analysis device connected to the fluorescence spectrophotometer are provided.

In the automatic control system of the methane fermentation tank described in Patent Document 2, the fermentation broth is sampled from the methane fermentation tub via the sampling line, and the fermentation broth is sent to the pretreatment apparatus. In the pretreatment apparatus, dilution of the fermentation broth, alkaline treatment for eluting the fluorescent substance F420 in the methanogen to the outside of the cells, heat treatment and the like are performed.

Then, the sample after the pretreatment is sent to a fluorescence spectrophotometer to measure the fluorescence intensity. In the measurement of the fluorescence intensity, the methane-producing bacterium is irradiated with light of 420 nm to make the fluorescent substance F420 glow pale, and the fluorescence intensity is measured by a fluorescence spectrophotometer. The measured fluorescence intensity data is sent to the data analyzer. The data analysis device analyzes the sent data and inputs the raw material liquid containing methanogens into the methane fermentation tank from the raw material tank via the raw material input line in the required amount at the required time. There is.

Japanese Unexamined Patent Publication No. 1-250041 Japanese Unexamined Patent Publication No. 8-154662

However, in the methane fermentation system described in Patent Document 1, as described above, it is necessary to provide a membrane filter and a washing control device for washing the subject in advance before irradiating the methanogen with excitation light. Therefore, large-scale equipment used for cleaning is required separately. In addition, since the subject used in the measurement is discharged as it is, there is a problem that it cannot be reused.

Further, in the methane fermentation system described in Patent Document 2, dilution of the fermentation broth, alkaline treatment for eluting the fluorescent substance F420 in the methanogenic bacteria to the outside of the cells, pretreatment such as heat treatment, and pretreatment are performed. You need reagents to do this.

Further, in the methane fermentation system described in Patent Document 1 and Patent Document 2, it is possible to measure methanogens in the methane fermentation tank at a certain time interval (time lag), but methane in the methane fermentation tank. There was a problem that the number of methanogens could not be measured in real time, and the accurate on-site measurement of methanogens was not considered at all.

Therefore, as a more efficient monitoring method for methanogens, the inventors examined measuring the number of methanogens during methane fermentation in real time on-site at a methane fermentation facility.

In view of such circumstances, the present invention provides a methane fermentation system capable of measuring the number of methanogens during methane fermentation in real time on-site in a methane fermentation facility and a method for monitoring methanogens. The purpose is.

The methane fermentation system according to the present invention is connected to a methane fermentation tank that produces methane gas by fermenting biomass using a methanogenic bacterium and the methane fermentation tank, and extracts a part of the digestive juice in the methane fermentation tank. Then, it is further provided with a circulation conduit for returning to the methane fermentation tank and a detection unit for detecting the amount of the methanogenic bacteria passing through the circulation conduit in a non-contact manner.

According to the methane fermentation system having the above configuration, it is connected to a methane fermentation tank that produces methane gas by fermenting biomass using methanogens and a methane fermentation tank, and a part of the digestive juice in the methane fermentation tank is extracted. Since it is provided with a circulation conduit for returning to the methane fermenter and a detection unit for detecting the amount of methanogenic bacteria passing through the circulation conduit in a non-contact manner, the detection unit does not come into direct contact with the methanogenic bacteria. The amount of methanogens that pass through the circulation conduit on contact can be detected.

In addition, large-scale equipment and the like are not required separately, and reagents used in pretreatment and pretreatment are not required. This makes it possible to circulate the digestive juice used to detect the amount of methanogens because it is not necessary to perform treatment that involves changes in the properties of the digestive juice in the methane fermenter. As a result, the number of methanogens during methane fermentation can be measured in real time on-site at the methane fermentation facility.

In addition, since the digestive juice used to detect the amount of methanogens is circulated, there is no need to discharge it, and a part of the digestive juice is circulated and returned to the methane fermentation tank for reuse in methane fermentation. Can be done. As a result, since the digestive juice is constantly flowing in the circulation conduit, dirt due to, for example, solids in the digestive juice does not adhere to the circulation conduit.

Further, for example, the pH value may be measured as an index for confirming the growth state of the methanogen in the methane fermenter. In such cases, the circulation conduit can be used in combination with the circulation pathway for measuring the pH value.

As one aspect of the present invention, the detection unit is provided in the circulation conduit, a transparent window portion that sees through the digestive juice inside the circulation conduit, a light source that irradiates the transparent window portion with light, and the transparency. It is preferable to include a photographing unit that detects the light reflected from the window unit and an image processing calculation unit that images the data photographed by the photographing unit.

According to the methane fermentation system having the above configuration, the detection unit is provided in the circulation conduit, and has a transparent window portion for seeing through the digestive juice inside the circulation conduit, a light source for irradiating the transparent window portion with light, and a transparent window portion. Since it is provided with a photographing unit that detects light reflected from the image and an image processing calculation unit that images the data photographed by the photographing unit, light is irradiated from the light source to the transparent window portion of the circulation conduit, and the transparent window portion is provided. The light reflected from the light source is detected (photographed) by the photographing unit, and the data photographed by the photographing unit is imaged by the image processing calculation unit.

Therefore, the amount of methanogens passing through the circulation duct can be detected without direct contact with the methanogens with a simple configuration such as a light source, a transparent window unit, a photographing unit, and an image processing calculation unit. This makes it possible to measure the number of methanogens during methane fermentation in real time on-site at a methane fermentation facility.

As another aspect of the present invention, it is preferable to further include a circulation pump provided in the middle of the circulation conduit.

According to the methane fermentation system having the above configuration, in order to further include a circulation pump provided in the middle of the circulation conduit, digestive juice is more efficiently delivered from the methane fermentation tank to the circulation conduit and digested in the circulation conduit. By constantly flowing the liquid, the digestive juice can be circulated efficiently.

As another aspect of the present invention, it is preferable that the circulation conduit further includes a baffle plate for introducing only the liquid component of the digestive juice in the region facing the transparent window portion.

Solids such as biomass and methanogens and liquids such as fermented liquids are present in the methane fermentation tank. According to the methane fermentation system having the above configuration, the circulation conduit faces the transparent window portion through the circulation conduit because the circulation conduit further includes a baffle plate for introducing only the liquid component of the digestive juice in the region facing the transparent window portion. Only the liquid content of the digestive juice can be efficiently introduced into the region.

Further, by providing the obstruction plate, the flow path (cross-sectional area) of the digestive juice near the transparent window portion can be narrowed, and the amount of the digestive juice (methane-producing bacteria) that becomes the detection symmetry can be reduced.

The method for monitoring methanogens of the present invention is a method for monitoring methanogens in a methane fermenter, and forms a circulation path for taking out the digested juice in the methane fermenter and returning it to the methane fermenter. A step of irradiating the surface of the circulation path with excitation light in a predetermined wavelength range, a step of detecting the amount of fluorescence of the coenzyme F420 peculiar to the methanogen, and the step of the amount of fluorescence per unit area. It is characterized by comprising a step of calculating the total amount.

According to the method for monitoring methanogens having the above configuration, it is a method for monitoring methanogens in a methane fermenter, and forms a circulation path for taking out the digested juice in the methane fermenter and returning it to the methane fermenter. The steps, the step of irradiating the surface of the circulation path with excitation light in a predetermined wavelength range, the step of detecting the fluorescence amount of the coenzyme F420 peculiar to methanogens, and the total amount of the fluorescence amount per unit area. Since it is provided with a step of calculating, it is not necessary to separate the methanogens one by one, and the amount of methanogens passing through the circulation conduit can be detected without direct contact with the methanogens. ..

In addition, large-scale equipment and the like are not required, and reagents used in pretreatment and pretreatment are not required. As a result, it is not necessary to perform a treatment involving a change in the properties of the digestive juice in the methane fermenter, and therefore it is not necessary to discharge the digestive juice used for detecting the amount of methanogens. Therefore, the digestive juice used to detect the amount of methanogens can be circulated, and a part of the digestive juice can be circulated and returned to the methane fermenter for reuse in methane fermentation. As a result, since the digestive juice is constantly flowing in the circulation conduit, dirt due to, for example, solids in the digestive juice does not adhere to the circulation conduit. In a methane fermentation facility, the number of methanogens during methane fermentation can be measured in real time on-site.

As yet another aspect of the present invention, the surface methanogen density in the digestive juice flowing into the circulation path is calculated from a pre-prepared methanogen density-fluorescence calibration line, and further divided by the cross-sectional area. It is preferable to further include a step of calculating the density of methanogens in the original digestive juice.

According to the methane-producing bacterium monitoring method having the above configuration, the surface methane-producing bacterium density in the digestive juice flowing into the circulation path is calculated from the methane-producing bacterium density-fluorescence calibration line prepared in advance, and the cross-sectional area is further calculated. In order to further prepare a step of calculating the density of methane-producing bacteria in the original digestive juice by dividing by, the methane-producing bacteria density-fluorescence calibration line is used to generate methane from the total amount of fluorescence per unit area. The bacterial density can be easily determined. This makes it possible to measure the number of methanogens during methane fermentation on-site in real time at a methane fermentation facility.

As described above, according to the methane fermentation system and the method for monitoring methanogens of the present invention, it is possible to measure the number of methanogens during methane fermentation on-site in real time at a methane fermentation facility. Can produce the effect.

It is a figure which shows the whole structure of the methane fermentation system which concerns on one Embodiment of this invention. It is an enlarged view which shows the structure of the detection part of the methane fermentation system which concerns on the same embodiment. It is a figure which shows the modification of the detection part of the methane fermentation system which concerns on the same embodiment.

Hereinafter, the outline of the methane fermentation system according to the embodiment of the present invention will be described with reference to the accompanying drawings.

The methane fermentation system according to the present embodiment is to be installed in a general methane fermentation facility or the like equipped with a methane fermentation apparatus for generating biogas such as methane gas, for example.

As shown in FIG. 1, the methane fermentation system 100 according to the present embodiment is connected to a methane fermentation tank 10 for producing methane gas by fermenting biomass using a methanogenic bacterium and a methane fermentation tank 10, and is connected to the methane fermentation tank. It is provided with a circulation conduit 11 that draws out a part of the digestive juice in 10 and then returns it to the methane fermentation tank 10, and a detection unit 12 that detects the amount of methanogenic bacteria passing through the circulation conduit 11 in a non-contact manner.

As the methane fermentation tank 10 according to the present embodiment, a general methane fermentation tank installed in a methane fermentation facility, a treatment facility for organic waste, or the like can be used. In the present embodiment, the methane fermentation tank 10 includes a bottom surface 10a and a side wall portion 10b rising from the bottom surface 10a.

The methane fermentation tank 10 is supplied with biomass such as organic waste, methanogens as fermenting bacteria, digestive juice, nutrients and the like. The type of biomass, fermenting bacteria, nutrients, type of digestive juice, etc. can be changed as needed.

As the number of methanogens required for methane fermentation, for example, ^{about 1 × 10 8} may be present in the methane fermentation tank 10. As a result of monitoring by the monitoring method of methanogens described later, the amount of methanogens input into the methane fermenter 10 every day is adjusted. For example, when methane fermentation is carried out in 40 days, 1/40 amount of methanogen may be added daily. The amount and composition of input materials can be adjusted by nutrition.

In the present embodiment, it is preferable that the circulation conduit 11 has a glass tube or a part of a side surface made of glass. In the present embodiment, the circulating conduit 11 is preferably quartz glass capable of transmitting light having an excitation wavelength of 420 nm and light having a fluorescence wavelength of 472 nm, but the material of the glass is not particularly limited. Further, the circulation conduit 11 is not limited to glass, and may be, for example, a hard and transparent material without weathering.

In the present embodiment, the circulation conduit 11 is connected to the outside of the side wall portion 10b of the methane fermentation tank 10. More specifically, the circulation conduit 11 is connected to a first conduit 11a extending horizontally from the outside of the side wall portion 10b of the methane fermenter 10 and a first vessel 11a, and is connected upward from the first vessel 11a. A second vessel 11b extending toward (vertically) and a third vessel 11c connected to the second vessel 11b and extending from the second vessel 11b toward the side wall of the methane fermenter 10. Be prepared.

As shown in FIG. 2, in the present embodiment, the detection unit 12 is provided in the circulation conduit 11, and irradiates the transparent window portion 13 that sees through the digestive juice inside the circulation conduit 11 and the transparent window portion 13 with light. The light source 14 is provided, a photographing unit 15 that detects (photographs) the light reflected from the transparent window unit 13, and an image processing calculation unit 16 that images the data photographed by the photographing unit 15.

In the present embodiment, the transparent window portion 13 has a substantially rectangular shape and is formed on the outer peripheral surface of the second conduit 11b.

The light source 14 irradiates the methanogen passing through the region facing the transparent window portion 13 with light of 420 nm, and makes the fluorescent substance F420 peculiar to the methanogen glow pale. As the light source 14, a commonly used light source can be used.

The photographing unit 15 detects (photographs) the fluorescence intensity of the reflected light of 470 nm reflected from the transparent window unit 13. In the present embodiment, a CCD camera is used as the photographing unit 15, but the present invention is not limited to this, and the fluorescence intensity of the reflected light of 470 nm reflected from the transparent window unit 13 can be detected (photographed). It should be.

The fluorescence intensity data detected and photographed by the photographing unit 15 is sent to the image processing calculation unit 16. The image processing calculation unit 16 images the data captured by the photographing unit 15 and displays it on a monitor (not shown) as an image display unit connected to the photographing unit 15 and displays the total amount of fluorescence per unit area. calculate.

As shown in FIG. 1, in the present embodiment, the methane fermentation system 100 further includes a circulation pump 17 provided in the middle of the circulation conduit 11.

The circulation pump 17 is not particularly limited, and pumps used for circulation such as general conduits and pipes can be used. In the present embodiment, the circulation pump 17 is provided in the middle of the first conduit 11a.

As shown in FIG. 3, in the present embodiment, the circulation conduit 11 further includes a baffle plate 18 for introducing only the liquid content L of the digestive juice in the region facing the transparent window portion 13.

A part or the whole of the obstruction plate 18 is formed in a mesh shape, the solid content S and the liquid content L of the digestive juice are separated, and only the liquid content L is introduced into the region facing the transparent window portion 13. It is configured to do.

In the present embodiment, the obstruction plate 18 is made of the same material as the transparent window portion 13. In the present embodiment, the baffle plate 18 is made of the same material as the transparent window portion 13, but is not limited thereto. The disturbing plate 18 may have a slit shape.

As shown in FIG. 3, the obstruction plate 18 is formed in a substantially triangular shape in a cross-sectional view. In the present embodiment, the baffle plate 18 is formed in a substantially triangular shape in a cross-sectional view, but the present invention is not limited to this, and any shape is possible.

As described above, according to the methane fermentation system 100 according to the present embodiment, the detection unit 12 detects the amount of methanogens passing through the circulation conduit 11 without direct contact with the methanogens. Can be done.

In addition, large-scale equipment and the like are not required separately, and reagents used in pretreatment and pretreatment are not required. As a result, it is not necessary to perform a treatment involving a change in the properties of the digestive juice in the methane fermenter 10, so that the digestive juice used for detecting the amount of methanogens can be circulated. As a result, the number of methanogens during methane fermentation can be measured in real time on-site at the methane fermentation facility.

In addition, since the digestive juice used to detect the amount of methanogens is circulated, there is no need to discharge it, and a part of the digestive juice is circulated and returned to the methane fermentation tank 10 for reuse in methane fermentation. be able to. As a result, since the digestive juice is constantly flowing in the circulation conduit 11, dirt due to solid content S or the like in the digestive juice does not adhere to the circulation conduit 11.

Further, in the measurement of methanogens, for example, the pH value may be measured as an index for confirming the growth state of the methanogens in the methane fermenter 10. In such a case, the circulation conduit 11 can be used in combination with the circulation route for measuring the pH value.

Further, in the detection unit 12, the light source 14 irradiates the transparent window portion 13 of the circulation conduit 11 with light of 420 nm, and the light of 472 nm reflected from the transparent window portion 13 is detected (photographed) by the photographing unit 15 and photographed. The data captured by the unit 15 is imaged by the image processing calculation unit 16.

Therefore, the detection unit 12 has a simple configuration of a light source 14, a transparent window unit 13, an imaging unit 15, and an image processing calculation unit 16, and produces methane through the circulation conduit 11 without direct contact with methanogens. The amount of bacteria can be detected. This makes it possible to measure the number of methanogenic bacteria in the methane fermentation tank 10 in real time on-site at the methane fermentation facility.

Further, the circulation pump 17 more efficiently sends the digestive juice from the methane fermentation tank 10 to the circulation conduit 11, and the digestive juice is constantly flowed into the circulation conduit 11 to efficiently circulate the digestive juice. be able to.

Further, the baffle plate 18 can efficiently introduce only the liquid content L of the digestive juice into the region facing the transparent window portion 13 through the circulation conduit 11.

Further, by providing the obstruction plate 18, the flow path (cross-sectional area) of the digestive juice near the transparent window portion 13 can be narrowed, and the amount of the digestive juice (methane-producing bacteria) that is symmetrical to be detected can be reduced.

The configuration of the methane fermentation system 100 according to the present embodiment has been described above. Next, the methane fermentation tank in the methane fermentation apparatus (not shown) using the methane fermentation system 100 according to the present embodiment is used. The work of monitoring the methanogenic bacteria in 10 will be described.

The method for monitoring methanogens in the methane fermentation tank 10 according to the present embodiment includes a step of taking out the digestive juice in the methane fermentation tank 10 and returning it to the methane fermentation tank 10 to form a circulation path, and a surface of the circulation path. A step of irradiating excitation light in a predetermined wavelength range, a step of detecting the amount of fluorescence of the coenzyme F420 peculiar to methanogens, and a step of calculating the total amount of fluorescence per unit area are provided.

More specifically, the method for monitoring methanogens in the methane fermenter 10 is a step of taking out the digested juice in the methane fermenter 10 and forming a circulation conduit 11 as a circulation path for returning it to the methane fermenter 10. Then, the surface of the circulation path (circulation conduit 11) is irradiated with excitation light having an excitation wavelength of 420 nm from the light source 14, and the imaging unit 15 detects the fluorescence amount of the coenzyme F420 peculiar to methanogens at 472 nm. It includes a step and a step of imaging the data taken by the photographing unit 15 by the image processing calculation unit 16 and calculating the total amount of fluorescence per unit area.

In the present embodiment, the method for monitoring the methanogen in the methane fermenter 10 is the surface in the digestive juice flowing into the circulation path (circulation conduit 11) from the metered line of the methanogen density-fluorescence amount prepared in advance. A step of calculating the methanogen density and further dividing by the cross-sectional area to calculate the methanogen density in the original digestive juice is further provided.

When measuring the number of methanogens in the methanogen 10 using the method for monitoring methanogens according to the present embodiment, first, as shown in FIG. 1, the digestive juice in the methanogen 10 is measured. A part of the digestive juice is sent out to the first conduit 11a by the circulation pump 17 and a part of the digestive juice is sent out to the second conduit 11b and the third conduit 11c in order, so that the circulation path (circulation conduit 11) To form. In FIG. 1, the flow of digestive juice in the circulation path (circulation conduit 11) is indicated by an arrow.

At this point, the process may immediately proceed to the next step, but for example, the solid content S in the digestive juice is to some extent on the lower side (bottom) of the second conduit 11b at predetermined time intervals. You may wait for it to accumulate before proceeding to the next step.

Initially, a part of the digestive juice in the methane fermentation tank 10 was sent to the first conduit 11a by the circulation pump 17, and the concentration of the solid content S in the digestive juice was about 10%. When a part of the digestive juice is sequentially sent to the second conduit 11b and the third conduit 11c to form a circulation channel (circulation conduit 11), the concentration of solid content S in the digestive juice Is about 8%.

Then, as shown in FIG. 2, light of 420 nm is irradiated from the light source 14 toward the transparent window portion 13. Next, the fluorescence amount of the coenzyme F420 peculiar to the methanogen is detected (photographed) by the photographing unit 15 from the fluorescence intensity of the reflected light of 470 nm reflected from the transparent window portion 13.

Then, as shown in FIGS. 1 and 2, the data photographed by the photographing unit 15 is sent to the image processing calculation unit 16. Next, the image processing calculation unit 16 images the data photographed by the photographing unit 15 and displays it on a monitor (not shown) as an image display unit connected to the photographing unit 15, and also creates a methane-producing bacterium in advance. From the density-fluorescence calibration curve, calculate the density of surface methanogens in the digestive juice flowing into the circulation path (circulation conduit 11), and divide by the cross-sectional area to obtain the density of methanogens in the original digestive juice. By calculating, the total amount of fluorescence per unit area is calculated.

Then, based on the calculated density of methanogens, the number of methanogens required for methane fermentation is charged into the methane fermentation tank 10 at any time.

As described above, according to the method for monitoring methanogens according to the present embodiment, it is necessary to separate methanogens one by one in order to estimate the amount of methanogens (total light intensity) based on the degree of luminescence of the entire surface. It is possible to detect the amount of methanogens passing through the circulation conduit in a non-contact manner without direct contact with methanogens.

In addition, large-scale equipment and the like are not required, and reagents used in pretreatment and pretreatment are not required. As a result, it is not necessary to perform a treatment involving a change in the properties of the digestive juice in the methane fermenter 10, and therefore it is not necessary to discharge the digestive juice used for detecting the amount of methanogens. Therefore, the digestive juice used to detect the amount of methanogens can be circulated, and a part of the digestive juice can be circulated and returned to the methane fermenter for reuse in methane fermentation.

As a result, since the digestive juice is constantly flowing in the circulation conduit 11, dirt due to solid content S or the like in the digestive juice does not adhere to the circulation conduit 11. This makes it possible to measure the number of methanogens during methane fermentation on-site in real time at a methane fermentation facility.

As described above, the number of methanogens required for methane fermentation may be, for example, about ^{1 × 10 8 in the methane fermentation tank 10.} As a result of monitoring by the monitoring method of methanogens, the amount of methanogens input into the methane fermenter 10 every day is adjusted. For example, when methane fermentation is carried out in 40 days, 1/40 amount of methanogen may be added daily. The amount and composition of input materials can be adjusted by nutrition.

It should be noted that the methane fermentation system and the method for monitoring methanogens of the present invention are not limited to the above-mentioned embodiments, and of course, they can be appropriately changed without departing from the gist of the present invention.

In the above embodiment, the circulation conduit 11 is connected to the first vessel 11a extending horizontally from the outside of the side wall portion of the methane fermenter 10 and the first vessel 11a, and is directed upward from the first vessel 11a. A second conduit 11b extending vertically (vertically) and a third conduit 11c connected to the second vessel 11b and extending from the second conduit 11b toward the side wall of the methane fermenter 10 are provided. , Not limited to this. For example, the circulation conduit 11 may be composed of a tube, a pipe, or the like, and may be configured to be directly inserted into the methane fermenter 10. In short, the circulation conduit 11 may be configured to form a circulation path for taking out the digestive juice in the methane fermentation tank 10 and returning it to the methane fermentation tank 10.

In the above embodiment, as a detection unit 12 for detecting the amount of methane-producing bacteria passing through the circulation conduit 11 in a non-contact manner, a transparent window portion 13 provided in the circulation conduit 11 and seeing through the digestive juice inside the circulation conduit 11 A light source 14 that irradiates the transparent window portion 13 with light, a photographing unit 15 that detects (photographs) the light reflected from the transparent window unit 13, and an image processing calculation unit 16 that images the data photographed by the photographing unit 15. , But not limited to this. In short, the detection unit 12 may be configured so as to be able to detect the amount of methanogens passing through the circulation duct in a non-contact manner.

In the present embodiment, the transparent window portion 13 has a substantially rectangular shape and is formed on the outer peripheral surface of the second conduit 11b, but is not limited thereto. In short, the transparent window portion 13 may be provided in the circulation conduit 11 so that the digestive juice inside the circulation conduit 11 can be seen through.

In the above embodiment, the circulation pump 17 is provided in the middle of the first conduit 11a, but is not limited thereto. The point is that the circulation pump 17 is provided in the circulation conduit 11 and more efficiently sends the digestive juice from the methane fermenter 10 to the circulation conduit 11 so that the digestive juice is constantly flowed into the circulation conduit 11. The structure may be such that the digestive juice can be circulated efficiently.

In the above embodiment, when a large amount of solid content S is present in the digestive juice in the methane fermenter 10, a coarse filter is provided in the circulation conduit 11 to flow the solid content S and the liquid content L. The path may be divided and only the methanogens diffused in the liquid component L may be measured.

In the above embodiment, the method for monitoring methanogens may further include a step of reverse-circulating the digestive juice in the circulation conduit 11 once at a predetermined time. By doing so, it is possible to prevent the circulation conduit 11 from being clogged with the solid content S such as biomass or methanogen, or the liquid content L such as digestive juice from adhering to the inner wall of the circulation conduit 11. Can be done.

Further, when the baffle plate 18 is provided in the region facing the detection unit 12, it is possible to improve problems such as clogging of the mesh shape of the baffle plate 18 with solid content S such as biomass and methanogens.

In the above embodiment, the detection unit 12 may be combined with a measuring instrument such as a flow cytometer.

The methane fermentation system and the method for monitoring methanogens of the present invention are effectively applied to a general methane fermentation facility or the like equipped with a methane fermentation apparatus for generating biogas such as methane gas.

10 Methanogen fermenter, 10a Bottom, 10b Side wall, 11 Circulation conduit, 11a First conduit, 11b Second conduit, 11c Third conduit, 12 Detection part, 13 Transparent window part, 14 Light source, 15 Imaging part, 16 image processing calculation unit, 17 circulation pump, 18 jam plate, 100 methane fermentation system, S solid content, L liquid content.

Claims (5)

A methane fermenter that ferments biomass using methanogens to produce methane gas,
A circulation conduit that is connected to the methane fermentation tank, draws out a part of the digestive juice in the methane fermentation tank, and then returns it to the methane fermentation tank.
A transparent window provided in the middle of the circulation conduit to see through the digestive juice passing through the circulation conduit.
Provided at a position facing the transparent window portion, the digestive juice is separated into a solid content and a liquid component, the liquid component is introduced into the region facing the transparent window portion, and the solid content passes through the other regions. With a window board to let you
A light source that irradiates the liquid component passing through the region facing the transparent window portion with excitation light,
An imaging unit that detects the fluorescence emitted from the coenzyme F420 of the methanogen by the excitation light through the transparent window unit.
A methane fermentation system including an image processing calculation unit that images the data photographed by the photographing unit. The methane fermentation system according to claim 1, further comprising a circulation pump provided in the middle of the circulation conduit. The methane fermentation system according to claim 1 or 2, wherein the obstruction plate is partially or wholly formed in a mesh shape. It is a method of monitoring methanogens in a methane fermenter.
A step of taking out the digestive juice in the methane fermentation tank and forming a circulation path to return it to the methane fermentation tank, and
A transparent window portion is provided at an intermediate position in the circulation path, and by introducing a liquid component into the region facing the transparent window portion and providing a baffle plate so as to allow solid content to pass through the other regions. , The process of separating the digestive juice into solid and liquid,
A step of irradiating the separated liquid component with excitation light in a predetermined wavelength range in the transparent window portion.
A step of detecting the amount of fluorescence of the coenzyme F420 peculiar to the methanogen by an imaging unit through the transparent window portion, and a step of detecting the fluorescence amount of the coenzyme F420.
A method for monitoring methanogens, which comprises a step of calculating the total amount of fluorescence per unit area in an image processing calculation unit that images data photographed by the imaging unit. From the methane-producing bacterium density-fluorescence calibration line prepared in advance, the surface methane-producing bacterium density in the digestive juice flowing into the circulation path is calculated, and further divided by the cross-sectional area to obtain methane in the original digestive juice. The method for monitoring methanogens according to claim 4, further comprising a step of calculating the density of methanogens.

Images