WO2017203684A1

WO2017203684A1 - Methane fermentation treatment system and methane fermentation treatment method

Info

Publication number: WO2017203684A1
Application number: PCT/JP2016/065713
Authority: WO
Inventors: 久智福井; 哲山澤; 一真石川
Original assignee: 鹿島建設株式会社
Priority date: 2016-05-27
Filing date: 2016-05-27
Publication date: 2017-11-30
Also published as: JPWO2017203684A1; JP6122232B1

Abstract

Provided are a methane fermentation treatment system and a methane fermentation treatment method in which organic waste water containing solid organic matter is subjected to methane fermentation so as to enable increasing of the amount of gas to be recovered. The methane fermentation treatment system 1a, 1b, 1c, 1d according to the present invention carries out methane fermentation by treating organic waste water containing solid organic matter using a methane fermentation microbial community, and is provided with: an endless water channel 11 through which the organic waste water is circulated; and a plurality of fixed beds 12 on which the methane fermentation microbial community is accumulated, wherein the distance between adjacent fixed beds 12 is 100-3000 mm. It is preferable to install the fixed beds 12 such that the lower ends thereof are situated at a height of at least 100 mm from the bottom of the endless water channel 11. Further, it is preferable for the inside of the endless water channel 11 to be provided with a redispersion device 14 for redispersing solid organic matter floating in the organic waste water.

Description

Methane fermentation treatment system and methane fermentation treatment method

The present invention relates to a methane fermentation treatment system and a methane fermentation treatment method.

廃 When wastewater with high organic matter content, such as domestic wastewater and industrial wastewater, flows into rivers, etc., exceeding the self-cleaning action of nature, water pollution progresses. Specifically, when organic wastewater flows into a river or the like, aerobic microorganisms temporarily grow and dissolved oxygen decreases. As a result, anaerobic microorganisms grow actively this time, and substances that cause off-flavors and substances that can affect the ecology of aquatic organisms are generated, which may affect the living environment and the natural environment.

In order to prevent such water pollution, appropriate purification treatment has been performed before discharging organic wastewater into rivers and the like. As means for purification treatment, for example, an activated sludge method, a methane fermentation method and the like are widely adopted.

Of these, the methane fermentation method is a method of generating methane by decomposing organic wastewater by anaerobic microorganisms. By this method, organic substances are decomposed into methane, carbon dioxide, water and the like. The generated methane can also be used as an energy source. Since methane fermentation is performed under anaerobic conditions, it does not require aeration power and is an energy-saving processing method. In addition, according to methane fermentation, wastewater having a high organic matter content can be decomposed and purified. The methane fermentation method is divided into a fixed bed method, a fluidized bed method, an upflow anaerobic sludge blanket (UASB) method, a plug flow method, a dry methane fermentation method, and the like depending on a method of loading or supporting a methane fermentation microorganism group. .

By the way, wastewater discharged from food processing plants, etc., containing solid organic matter such as straw, and flowing methane fermentation microorganisms in the treatment of high-concentration wastewater with a suspended solid (SS) concentration of 1,000 mg / L or more, for example When a fluidized bed method using a support carrier or a UASB method for granulating the methane fermentation microorganism group itself is used, the methane fermentation microorganism group flows out together with the waste water, and efficient treatment cannot be performed.

Also, as an efficient methane fermentation technique, a fixed bed method in an endless water channel has been proposed (for example, see Patent Document 1). However, when high-SS concentration wastewater discharged from food processing factories and the like is treated by such a method, soot is retained between fixed beds, etc., and clogging occurs or solid organic matter is settled, which is efficient. May not be able to be processed.

On the other hand, in order to treat waste water containing solid organic matter, a fixed bed method using a hollow cylinder having a diameter of 50 to 80 mm as a fixed bed has been proposed (for example, see Patent Document 2 and Patent Document 3). However, in these methods, it is necessary to perform a pretreatment for pulverizing the solid organic matter in order to prevent clogging in the hollow cylinder, which requires labor and cost. For this reason, the wastewater treatment by the fixed bed method still has room for improvement from the viewpoint of simplifying the pretreatment of the solid organic matter.

On the other hand, in order to treat coarse solid organic matter, treatment by plug flow method or dry methane fermentation method has been proposed, but the concentration of methane fermentation microorganisms in the tank cannot be increased, so the fermentation rate is slow. .

Thus, there is a demand for efficient methane fermentation without further pulverizing coarse solid organic matter obtained by a simple pulverization process.

JP 2012-5971 A Japanese Patent Laid-Open No. 7-80435 JP 11-207379 A

This invention is made | formed in view of this problem, and it aims at providing the methane fermentation processing system and methane fermentation processing method which can carry out the methane fermentation of the organic waste water containing a solid organic matter efficiently. .

(1) A first invention of the present invention is a methane fermentation treatment system for treating organic wastewater containing solid organic matter with a methane fermentation microorganism group to cause methane fermentation, and an endless water channel through which the organic wastewater circulates. And a plurality of fixed beds on which methane fermentation microorganisms are accumulated, and a distance between the adjacent fixed beds is 100 mm or more and 3000 mm or less.

(2) The second invention of the present invention is the methane fermentation treatment system according to the first invention, wherein the fixed floor is installed such that the lower end of the fixed floor is at least 100 mm above the bottom of the endless water channel. .

(3) The third invention of the present invention is the methane fermentation treatment according to the first or second invention, comprising a redispersion device for redispersing the solid organic matter floating in the organic waste water in the endless water channel. System.

(4) According to a fourth aspect of the present invention, there is provided the heating apparatus according to any one of the first to third aspects, wherein the temperature of the organic waste water in the endless water channel is heated to 50 ° C. or higher and 65 ° C. or lower. It is a methane fermentation treatment system.

(5) According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the organic wastewater contains a solubilized microorganism group, and the endless water channel has a length of 100 mm or less. It is a methane fermentation treatment system provided with an organic matter holding device that is formed of a net having holes and holds solid organic matter having a particle size larger than the size of the holes.

(6) According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the organic wastewater contains a solubilized microorganism group and stores solid organic matter. In the solid matter decomposition tank, the solid organic matter in the solid matter decomposition tank is dissolved by the organic wastewater containing the solubilized microorganism group supplied from the endless water channel, and has a hole of 100 mm or less. It is the methane fermentation processing system discharged | emitted in the said endless water channel from an exit.

(7) The seventh invention of the present invention is the methane fermentation treatment system according to any one of the first to sixth inventions, wherein the suspended solid (SS) concentration of the organic waste water is 1,000 mg / L or more.

(8) The eighth invention of the present invention is a methane fermentation treatment method in which organic wastewater containing solid organic matter is treated with methane fermentation microorganisms to perform methane fermentation, and a plurality of fixed beds on which the methane fermentation microorganisms are accumulated And the organic wastewater is circulated in an endless water channel having a distance between adjacent fixed beds of 100 mm or more and 3000 mm or less.

(9) According to a ninth aspect of the present invention, in the eighth aspect, the organic wastewater contains a solubilized microorganism group, and has a hole having a size of 100 mm or less in the endless water channel. An organic substance holding device that is composed of a net-like body and holds solid organic matter having a particle size larger than the size of the pores is installed therein, and the organic matter holding device is circulated along with the circulation of the organic wastewater in the endless water channel. It is the methane fermentation processing method which dissolves the said solid organic matter currently hold | maintained in.

(10) A tenth aspect of the present invention is the solubilized microorganism according to the eighth or ninth aspect, wherein a solid organic substance is stored, a solid matter decomposition tank provided with a discharge port having a hole having a diameter of 100 mm or less is installed. In the methane fermentation treatment method, the solid organic matter in the solid matter decomposition tank is dissolved by an organic wastewater containing a group, and the solid organic matter is discharged from the discharge port into the endless water channel.

According to the present invention, when methane fermentation is performed in an endless water channel and the distance between a plurality of fixed beds is set within a predetermined range, methane gas is efficiently generated when treating organic wastewater containing solid organic matter. Can be generated.

It is a figure for demonstrating the flow for collect | recovering methane gas from the waste from a food processing factory. It is a figure for demonstrating the structure of a methane fermentation processing system. It is a figure for demonstrating the structure of the methane fermentation processing system which concerns on another aspect. It is a figure for demonstrating the structure of a fixed floor. It is a figure for demonstrating the structure of a fixed floor unit. It is a figure for demonstrating the structure of a fixed floor unit. It is a figure for demonstrating the structure of an organic substance holding | maintenance apparatus. It is a figure for demonstrating the structure of a solid substance decomposition tank. It is a graph which shows the examination result of the installation height of a fixed floor in Example 2, and the deposit height.

Hereinafter, a specific embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. Note that the present invention is not limited to the following embodiment, and can be implemented with appropriate modifications within the scope of the object of the present invention.

<< 1. Methane fermentation treatment equipment≫
FIG. 1 is a schematic configuration diagram of equipment for recovering methane gas from organic wastewater containing solid organic matter discharged from a food processing factory or the like. The methane fermentation treatment facility 100 is a facility that treats organic wastewater containing solid organic matter with a methane fermentation microorganism group and collects methane gas. The methane fermentation treatment system 1, the storage tank 2, the mixing tank 3, and the pulverizer 4.

For example, organic waste discharged from the food processing factory 5 or the like is divided into solid organic matter and waste water. In the methane fermentation treatment facility 100, the solid organic matter discharged from the food processing factory 5 is easily pulverized in the pulverization apparatus 4. Next, in the mixing tank 3, the solid organic matter after simple pulverization and waste water discharged from the food processing factory 5 are mixed. Next, the organic wastewater containing solid organic matter obtained by mixing the solid organic matter and wastewater is transferred to the storage tank 2 as a raw material of methane gas and stored in the storage tank 2. Thereafter, the organic wastewater containing the solid organic matter stored in the storage tank 2 is transferred to the methane fermentation treatment system 1, and the methane fermentation treatment is performed in the methane fermentation treatment system 1. Methane gas generated in the methane fermentation treatment system 1 is recovered and can be used for use in a factory, power generation, gas concentration, and the like.

Here, the “solid organic matter” is not limited to granular solid matter but includes fibrous solid matter, planar solid matter, and aggregates thereof. The “particle size” in such a case refers to the longest portion of the solid organic matter.

(1) Pulverization device The pulverization device 4 is a device that pulverizes the raw material of solid organic matter supplied from, for example, the food processing factory 5. As will be described in detail later, in the methane fermentation treatment system 1, since it is possible to efficiently treat even a coarse solid organic matter, in this pulverization apparatus 4, it is not necessary to finely pulverize the solid organic matter, A simple pulverization process can be performed. In addition, even if it is a solid organic substance containing the particle size of 10 mm or more as a solid organic substance, according to the methane fermentation treatment system 1, a methane fermentation process can be performed efficiently.

The pulverizer 4 can be configured by a simple device such as a rotary blade pulverizer or a hammer pulverizer. Moreover, solid biomass, such as napier grass, can be supplied to the pulverizer 4 from the outside, for example, and it can be used as a raw material for methane fermentation treatment together with solid organic matter discharged from the food processing factory 5.

(2) Mixing tank The mixing tank 3 is supplied with solid organic matter pulverized in the pulverizing apparatus 4 and waste water from the food processing factory 5, and mixes the solid organic matter and waste water to obtain organic waste water containing the solid organic matter. For example, the mixing tank 3 can be constituted by various tanks or the like according to the amount of waste water to be mixed, the water temperature, or the like.

(3) Storage tank The storage tank 2 is provided in the front | former stage of the methane fermentation processing system 1, and stores the organic waste water containing a solid organic matter. For example, the storage tank 2 can be composed of various tanks or the like according to the amount of organic waste water containing solid organic matter, the water temperature, and the like.

The storage tank 2 is connected to the methane fermentation treatment system 1 by piping or the like, and supplies organic wastewater containing solid organic matter to the methane fermentation treatment system 1 while adjusting the supply amount by a known liquid supply means such as a pump. To do. In addition, supply of the organic waste water containing the solid organic matter to the methane fermentation treatment system 1 may be performed continuously, or may be performed intermittently for every fixed supply amount.

(4) Methane fermentation treatment system The methane fermentation treatment system 1 is a reaction field in which methane fermentation treatment is performed on organic wastewater containing solid organic matter supplied from the storage tank 2 to generate methane gas.

As will be described in detail later, in this methane fermentation treatment system 1, organic wastewater containing solid organic matter can be treated efficiently, and the amount of methane gas produced can be increased.

≪2. Methane fermentation treatment system >>
As described above, the methane fermentation treatment system 1 according to the present embodiment performs methane fermentation treatment of organic wastewater containing solid organic matter using a methane fermentation microorganism group. FIG. 2 is a diagram illustrating an example of the configuration of the methane fermentation treatment system according to the present embodiment. As shown in FIG. 2, the methane fermentation treatment system 1 includes an endless water channel 11 through which organic wastewater containing solid organic matter circulates and a plurality of fixed beds 12 in which methane fermentation microorganisms are accumulated. And in this methane fermentation processing system 1, it is comprised so that the distance between adjacent fixed beds may be 100 mm or more and 3000 mm or less.

<2-1. Specific configuration>
In the methane fermentation treatment system 1, organic wastewater containing solid organic matter is supplied to the endless water channel 11 (L 1) and circulates in the endless water channel 11. Along with the circulation, the organic waste water containing the solid organic matter comes into contact with the fixed bed 12 and is subjected to anaerobic treatment by the group of methane fermentation microorganisms accumulated on the fixed bed 12, whereby the organic matter is decomposed by methane fermentation. In the methane fermentation treatment system 1, a methane gas production reaction occurs due to such decomposition of organic substances. The generated biogas is then recovered (G1) and can be used as an energy resource.

(1) Endless water channel In the endless water channel 11, anaerobic conditions are obtained by circulating organic waste water containing solid organic matter and bringing it into contact with the fixed bed 12 in which the methane fermentation microorganism group provided in the endless water channel 11 is accumulated. Under the methane fermentation treatment of organic wastewater containing the solid organic matter.

Thus, by circulating the organic wastewater containing the solid organic matter in the endless water channel 11, the organic wastewater containing the solid organic matter can be mixed and stirred with power saving, while reducing the operating cost, The degradation substrate and the methane fermentation microorganism group can be contacted efficiently. Thereby, the methane fermentation processing capability equivalent to or more than that of the conventional methane fermentation processing apparatus can be achieved.

Specifically, the endless water channel 11 may have a rounded rectangular shape as shown in a plan view from directly above shown in FIG. Further, it may be circular, elliptical or the like. Thus, as the shape when the endless water channel 11 is viewed in plan, it is a shape without corners, so that it is possible to prevent the organic waste water containing solid organic matter from staying and to circulate more efficiently. it can.

Further, in the endless water channel 11, it is preferable to make the distance through which the organic waste water containing solid organic matter circulates, that is, the distance per one end of the endless water channel 11, as long as possible. The opportunity of contact with the fixed floor 12 being made can be increased. Specifically, for example, as shown in FIG. 2, it is preferable that the endless water channel 11 has a long distance between the straight portions.

Further, the endless water channel 11 may have a shape in which the flow of the waste water is folded back multiple times per round. FIG. 3 is a schematic view of another embodiment of the methane fermentation treatment system. As shown in FIG. 3, in the methane fermentation treatment system 1 b, the endless water channel 11 ′ has a shape such that a plurality of endless water channels 11 shown in FIG. 2 are connected. In this endless water channel 11 ', there are provided five places where the flow of waste water is folded back in the direction opposite to the flow direction so far. In this way, by forming a shape in which a plurality of wastewater flows are folded back, the distance through which organic wastewater containing solid organic matter circulates can be increased even when the installation area is small. Thereby, the fixed bed 12 which can be installed per area can be increased, the contact opportunity of the organic waste water containing solid organic matter and the fixed bed 12 can be increased, and methane fermentation efficiency can be improved.

The size, depth, and the like of the endless water channel 11 are not particularly limited, and can be appropriately changed in consideration of the methane fermentation treatment amount, the installation location, and the like. Further, the material of the endless water channel 11 is not particularly limited, but can be formed of, for example, reinforced concrete.

Moreover, it is preferable that the endless water channel 11 has a substantially sealed structure in order to maintain anaerobic conditions in which methane fermentation is performed. The means for providing a substantially sealed structure is not particularly limited.

The flow rate of the organic wastewater containing solid organic matter that circulates in the endless water channel 11 is not particularly limited, but is preferably set to 3 m / h or more, and more preferably set to 10 m / h or more, More preferably, it is set to 30 m / h or more. By setting the flow rate of the organic wastewater containing solid organic matter to 3 m / h or more, the organic wastewater containing solid organic matter can be circulated well in the endless water channel 11 and methane fermentation can be performed efficiently. . In addition to this, by setting the flow rate of organic wastewater containing solid organic matter to 30 m / h or more, solid organic matter in organic wastewater containing solid organic matter is deposited while maintaining a sufficient flow rate in the endless water channel 11. It can be circulated while preventing it more effectively.

Further, the treatment temperature of the methane fermentation treatment in the endless water channel 11 is not particularly limited, but the temperature of the organic wastewater containing the circulated solid organic matter is medium temperature (around 37 ° C., for example, 30 to 40 ° C.) or high temperature (55 ° C.). It is preferable that the temperature is approximately before and after, for example, 50 to 65 ° C. In general, in the methane fermentation treatment, the reaction proceeds even at room temperature, but from the viewpoint of increasing the reaction efficiency of methane fermentation, it is preferable to set the reaction at a medium temperature and high temperature. In addition, the temperature of the organic waste water containing solid organic matter can be adjusted by providing the heating device mentioned later in the endless water channel 11.

Further, in the endless water channel 11, there may be a solubilizing microorganism group that solubilizes organic substances other than the methane fermentation microorganism group in the organic wastewater containing the circulating solid organic substances. Thus, by the presence of the solubilized microorganism group in the organic wastewater containing the solid organic matter, the solid organic matter dispersed in the organic wastewater containing the solid organic matter can be decomposed and solubilized and liquefied. By reducing the particle size of the solid organic material, the dispersibility and circulation of the solid organic material can be improved. Although the mechanism of this degradation has not been completely elucidated, organic substances (eg, carbohydrates, proteins, lipids) whose solubility has been increased under high temperature conditions have been reduced in molecular weight (eg, sugars, amino acids, peptides, etc.) Further, it is considered that a part or most of the acid is decomposed to an organic acid such as acetic acid by acid decomposition. And methane fermentation is made | formed by the methane fermentation microorganisms group using this low molecular weight organic substance as a substrate.

(2) Fixed bed The fixed bed 12 is capable of accumulating a group of methane fermentation microorganisms that perform methane fermentation, and a plurality of fixed beds 12 are installed in the endless water channel 11. In the methane fermentation treatment system 1, the organic wastewater containing solid organic matter comes into contact with the fixed bed 12 provided in the endless water channel 11, whereby the methane fermentation treatment by the methane fermentation microorganism group accumulated on the fixed bed 12 is performed. Is called.

FIG. 4 is a diagram illustrating an example of the configuration of the fixed floor 12. As shown in FIG. 4, each fixed bed 12 includes a base material 121 and a fixing portion 122 provided on the surface of the base material 121, and a methane fermentation microorganism group is accumulated in the fixing portion 122. The methane fermentation treatment is performed on the solid organic matter by the methane fermentation microorganism group. Thus, by installing the fixed bed 12 on which methane fermentation bacteria are accumulated, the contact opportunity between the organic wastewater containing solid organic matter and the fixed bed 12 can be increased, and the methane fermentation efficiency can be increased.

The base material 121 serves as a substrate for the fixed floor 12 and is not particularly limited, and is composed of, for example, a frame, a plate-like body, or the like.

The fixing unit 122 is not particularly limited as long as the methane fermentation microorganism group is accumulated, and the fixing part 122 is made of a material that can accumulate the methane fermentation microorganism group. Specifically, for example, aramid fiber, glass fiber, cellulose fiber, nylon fiber, vinylon fiber, polyester fiber, polyolefin fiber, woven or non-woven fabric made of felt, carbon fiber made of acrylic fiber, etc. It can be comprised with a nonwoven fabric, polyester cotton, etc. Such a material is preferable because it is porous and easily accumulates microorganisms, is relatively inexpensive, and is easy to install.

The fixed bed 12 is installed in a circulation area in which organic wastewater containing solid organic matter circulates in the endless water channel 11. Specifically, as illustrated in FIG. 2, the fixed floor 12 a can be installed on the peripheral wall surface of the endless water channel 11. Moreover, the installation surface of the fixed floor 12 can be separately provided in the endless water channel 11, and the fixed floor 12b can also be installed in the location.

The installation direction of the fixed floor 12 is not particularly limited, but from the viewpoint of preventing solid organic matter from accumulating on the surface of the fixed floor 12, it is substantially perpendicular to the water surface of the endless water channel 11 and to the flow of waste water. It is preferable to install them substantially in parallel.

Further, the installation method of the fixed floor 12 is not particularly limited, and for example, the fixed floor 12 can be installed on the peripheral wall surface of the endless water channel 11, the fixed floor installation surface, or the like. Moreover, the fixed floor 12 can also be comprised by sticking and fixing the fixing | fixed part 122 in which a methane fermentation microorganisms group is integrated | stacked on base materials 121, such as a frame body and a plate-shaped body which were installed beforehand.

The fixed floor 12 is not limited to installing the fixed floor 12 configured as described above alone, and a plurality of the fixed floors 12 may be connected to form a fixed floor unit. For example, FIG. 5 is a diagram illustrating an example of the configuration of the fixed floor unit. FIG. 6 is a diagram illustrating a configuration of a fixed floor unit according to another aspect. As shown in Fig. 6, a plurality of fixed floor units 12 'can be installed in parallel so as to face each other at a predetermined interval to constitute one fixed floor unit 12 ". By using the floor units 12 ′ and 12 ″, installation and maintenance of the fixed floor 12 are facilitated.

Here, in the methane fermentation treatment system 1 according to the present embodiment, adjacent intervals d of the plurality of fixed beds 12 provided in the endless water channel 11 (“d” in FIGS. 2, 3, and 6). ”) Is set to be 100 mm or more. The “interval between adjacent fixed floors 12” refers to the shortest distance between adjacent fixed floors 12.

Further, the interval (d) between the adjacent fixed floors 12 is preferably 200 mm or more, more preferably 300 mm or more, and particularly preferably 500 mm or more. In this way, by setting the distance (d) between the adjacent fixed floors 12 to 100 mm or more, the organic waste water containing the solid organic matter is effectively contained in the endless water channel 11 while preventing the blockage in the endless water channel 11. Can be circulated.

The upper limit of the distance (d) between the adjacent fixed floors 12 is preferably 3000 mm or less, more preferably 2000 mm or less, and even more preferably 1000 mm or less. Thus, by setting the distance (d) between the adjacent fixed beds 12 to 3000 mm or less, the contact probability and contact opportunity between the organic wastewater containing solid organic matter and the fixed beds 12 can be maintained high, and methane fermentation can be performed. Can be done efficiently.

Further, the fixed floor 12 is not particularly limited, but is preferably installed with a predetermined height from the bottom surface in the endless water channel 11. The “installation height of the fixed floor 12” (“h” in FIG. 6) refers to the height from the bottom surface in the endless water channel 11 to the lower end of the fixed floor. Can be installed at a predetermined interval from the bottom surface of the endless water channel 11. Thus, by providing a fixed floor with a gap from the bottom surface in the endless water channel 11, a sufficient flow velocity can be secured even at the bottom of the endless water channel 11, and at the bottom of the endless water channel 11. Accumulation of solid organic matter can be prevented.

Specifically, the installation height (h) of the fixed floor 12 is preferably set so that the lower end of the fixed floor 12 has a height of 100 mm or more from the bottom of the endless water channel 11 and has a height of 200 mm or more. It is more preferable to install in such a way that it is more preferably 300 mm or more.

The upper limit of the installation height (h) of the fixed bed 12 is not particularly limited as long as the methane fermentation can be efficiently performed while maintaining the contact probability between the organic wastewater containing solid organic matter and the fixed bed 12, For example, it is preferable to set it as 1000 mm or less from the bottom part of the endless water channel 11, and it is more preferable to set it as 500 mm or less.

(3) Heating device In the methane fermentation treatment system 1, a heating device can be provided in the endless water channel 11. The heating device heats and adjusts the temperature of the organic wastewater containing the solid organic matter in the endless water channel 11 and holds it at a predetermined temperature. By setting the temperature of the organic wastewater containing the solid organic matter to an intermediate temperature or high temperature, the methane fermentation efficiency of the organic matter (purification ability of the organic wastewater containing the solid organic matter) can be increased, and the endless water channel 11 can be reduced in size.

The heating device is not particularly limited, and for example, a heater, a thermostat, or the like can be used. Moreover, it does not specifically limit as an installation location of a heating apparatus.

(4) Circulation device In the methane fermentation treatment system 1, a circulation device can be provided in the endless water channel 11. The circulation device circulates organic wastewater containing solid organic matter in the endless water channel 11.

The circulation device is not particularly limited. For example, as shown in FIG. 2, a stirring blade (circulation device 13) can be used. Although not shown, a pump or the like can be used.

The circulation device can be installed at a specific location in the endless water channel 11 or can be installed at a plurality of locations. Moreover, about the specific installation location, direction, etc. of a circulation apparatus, it can set suitably so that circulating water may be circulated in a fixed direction.

(5) Redispersion device Moreover, in the methane fermentation treatment system 1, a redispersion device can be provided in the endless water channel 11. The redispersion device again disperses the solid organic matter such as scum floating on the surface of the organic wastewater containing the solid organic matter in the endless water channel 11 in the organic wastewater containing the solid organic matter.

The redispersing device 14 is not particularly limited, and for example, as shown in FIG. 2, a stirring blade (redispersing device 14) can be used. By providing and rotating the redispersion device 14 constituted by stirring blades in the endless water channel 11, the solid organic matter floating on the water surface of the organic wastewater containing the solid organic matter can be redispersed. Moreover, as a redispersion apparatus, it can be comprised by the apparatus which precipitates circulating water flow, such as a shower, from the upper part of the endless water channel 11, for example, The solid organic substance which floated can also be redispersed with this apparatus.

In addition, when a stirring blade is used as the redispersion device 14, it can also serve as the circulation device 13 described above.

(6) Suction Port In the methane fermentation treatment system 1, the endless water channel 11 can be provided with a suction port for sucking the solid organic matter accumulated at the bottom of the water channel. In the endless water channel 11, solid organic matter may be deposited at the bottom of the endless water channel 11, which may cause stagnation of organic wastewater containing the solid organic matter. At this time, by providing a suction port for sucking the solid organic matter and sucking and removing the accumulated solid organic matter, the retention of the organic waste water containing the solid organic matter can be suppressed and the maintenance frequency can be reduced.

(7) Organic matter holding device Moreover, in the methane fermentation treatment system 1, in the endless water channel 11, it is formed by a mesh having pores of 100 mm or less, and holds solid organic matter having a particle size larger than the size of the pores inside. An organic substance holding device can be provided.

Specifically, FIG. 7 is a configuration diagram illustrating an example of a methane fermentation treatment system including an organic substance holding device. As shown in FIG. 7, the methane fermentation treatment system 1 c includes an organic substance holding device 15 at a position where an organic wastewater containing solid organic substances flows in the endless water channel 11.

In the methane fermentation treatment system 1c, when such an organic matter holding device 15 is installed in the endless water channel 11, the organic matter holding device 15 holds the solid organic matter having a particle size larger than the pore size. It dissolves gradually by the action of solubilizing microorganisms in the organic wastewater that it contains, and its particle size decreases. When the solid organic matter becomes smaller than the size of the hole of the organic substance holding device 15 that is a net-like body, it elutes from the hole of the net-like body and circulates through the endless water channel 11.

The organic substance holding device 15 is a net-like body having a hollow shape such as a cage shape or a cylindrical shape and having a hole having a diameter of 100 mm or less. Moreover, the organic substance holding | maintenance apparatus 15 hold | maintains the solid organic substance of a particle size larger than the magnitude | size of the hole in the space inside. When the size of the hole of the organic substance holding device 15 is 100 mm or less, it is possible to prevent a coarse solid organic substance from being discharged into the endless water channel 11 and to suppress the retention of the solid organic substance in the endless water channel 11. The “diameter” means the longest distance among the distances from the end of the hole.

Thus, by providing the organic substance holding device 15 that holds the solid organic substance having a large particle diameter, the solid organic substance having a large particle diameter is subjected to the methane fermentation treatment without performing a pretreatment such as pulverization on the solid organic substance. be able to.

(8) Solid matter decomposition tank In addition, in the methane fermentation treatment system 1, the solid substance decomposition tank 16 storing solid organic matter can be provided separately from the endless water channel 11.

Specifically, FIG. 8 is a configuration diagram illustrating an example of a methane fermentation treatment system including a solid matter decomposition tank. As shown in FIG. 8, the methane fermentation treatment system 1 d includes a solid matter decomposition tank 16 separately from the endless water channel 11.

The solid matter decomposition tank 16 stores solid organic matter therein and is connected to the endless water channel 11 by two pipes (L2, L3). A discharge port 161 having a hole with a size of 100 mm or less is provided in the vicinity of one pipe (L3).

The solid matter decomposition tank 16 discharges and supplies to the endless water channel 11 a solid organic substance having a particle diameter smaller than a predetermined particle size among the solid organic substances stored in the tank. The solid organic matter contained in the solid matter decomposition tank 16 is gradually dissolved by the action of the solubilizing microorganisms in the organic wastewater, and the particle size becomes small. In this way, the solid matter decomposition tank 16 decomposes the solid organic matter to a particle size (for example, 100 mm or less) that allows the inside of the endless water channel 11 to circulate, and discharges and supplies the solid organic matter into the endless water channel 11. be able to.

Here, the two pipes (L2, L3), for example, use a pump or the like (not shown) to mutually exchange organic waste water containing solid organic matter between the endless water channel 11 and the solid matter decomposition tank 16. To be transported. Moreover, the direction of the flow of the organic waste water containing the solid organic matter is a direction (L2) from the endless water channel 11 to the solid material decomposition tank 16, and a direction (L3) from the solid material decomposition tank 16 to the endless water channel 11 Respectively.

One pipe (L2) transfers the organic waste water containing the solid organic matter from the endless water channel 11 to the solid matter decomposition tank 16. Accordingly, the solubilized microorganism group in the organic waste water containing the solid organic matter is supplied to the solid matter decomposition tank 16. The solid organic matter stored in the solid matter decomposition tank 16 is partially eluted by the action of the solubilized microorganisms that have flowed in this way, and becomes smaller until discharged into the endless water channel 11.

The other pipe (L3) is for discharging organic waste water containing solid organic matter from the solid matter decomposition tank 16 to the endless water channel 11. In the vicinity of the outlet of the solid substance decomposition tank 16, for example, as shown in FIG. 8, a discharge port 161 having a hole with a size of 100 mm or less is provided. When the particle size of the solid organic matter in the solid matter decomposition tank 16 becomes equal to or smaller than the hole of the discharge port 161 due to the action of the solubilized microorganism group, it passes through the hole of the discharge port 161 and passes through the pipe (L3). To be used for methane fermentation.

As the discharge port 161, for example, a filter having a plurality of holes having a size of 100 mm or less, a tube having a size of 100 mm or less, or the like can be used.

Even when the discharge port 161 is not used, for example, when the solid organic matter stored in the solid matter decomposition tank 16 becomes smaller than a predetermined particle size, or when the solid organic matter is stored in the solid matter decomposition tank 16. Can be discharged into the endless water channel 11 through the pipe (L3).

Further, instead of supplying the organic waste water containing the solid organic matter from the endless water channel 11, water containing the solubilized microorganism group can be supplied from other than the endless water channel 11 to the solid matter decomposition tank. In such an embodiment, the water containing the solubilized microorganism group is supplied to the solid decomposition tank, and after the solid is dissolved in the solid decomposition tank, the solid organic matter that has become smaller than the hole in the discharge port, It can also be discharged into the endless water channel through the pipe (L3). In this case, the pipe (L2) for supplying the organic waste water containing the solid organic matter from the endless water channel 11 may not be configured. Thus, even if it comprises a solid substance decomposition tank, the effect similar to the effect mentioned above can be acquired.

The methane fermentation treatment system 1d provided with such a solid matter decomposition tank 16 can be subjected to methane fermentation treatment without pretreatment such as pulverization of the solid organic matter.

<2-2. About organic wastewater containing solid organic matter>
As described above, in the methane fermentation treatment system 1 according to the present embodiment, the organic wastewater containing solid organic matter is circulated in the endless water channel 11 to perform the methane fermentation treatment. Specifically, the organic wastewater containing the solid organic matter used for the methane fermentation treatment is a wastewater containing a solid organic matter, for example, an organic matter having an SS concentration of 1,000 mg / L or more. Organic wastewater includes, for example, domestic wastewater (including wastewater generated by kitchen baths, washing, cleaning, etc.), industrial wastewater (food factories, biofuel manufacturing factories, other factories, etc.) Including industrial wastewater generated, livestock manure, etc.), water mixtures of various pollutants and other organic waste, and sewage mixed with rainwater.

Here, solid organic substances such as decanter cakes generated from a straw processing factory, solid organic substances such as palm coconut shells and oil scum generated from a palm oil factory, solid organic substances such as okara generated from a soybean processing factory are conventional methane. Since it is difficult to process in a fermentation processing system, it is often discarded. On the other hand, according to the methane fermentation treatment system 1, such a solid organic material can be mixed with waste water without being finely pulverized, and methane fermentation can be performed, and the amount of methane gas generated can be increased.

Specifically, when subjecting a solid organic substance such as a decanter cake generated from a straw processing factory or the like to methane fermentation, the solid organic substance is mixed with waste water before being introduced into the endless water channel 11. The mixing ratio of the solid organic matter such as the decanter cake is not particularly limited, but is preferably 0.5 wt / wt or less with respect to the organic wastewater discharged from the factory. By setting the weight ratio of the solid organic matter to 0.5 wt / wt or less, the fluidity can be enhanced to such an extent that the organic wastewater containing the solid organic matter can be circulated in the endless water channel 11. Such organic wastewater containing solid organic matter is subjected to a methane fermentation treatment for, for example, raw material residence time (also referred to as HRT (Hydraulic Retention time) or hydraulic residence time) for one day or more, such as a decanter cake. More than 70% of the solid organic matter can be converted into methane gas.

Even when solid organic matter such as palm coconut shells generated from a palm oil factory is subjected to methane fermentation treatment, the solid organic matter is mixed with waste water before being introduced into the endless water channel 11. Although it does not specifically limit as a particle size of solid organic substances, such as palm coconut shell, It is preferable to grind | pulverize and add to 50 mm or less. By setting the particle size of the solid organic matter such as palm coconut shell to 50 mm or less, the fluidity can be enhanced to such an extent that the organic wastewater containing the solid organic matter can circulate in the endless water channel 11. By subjecting organic wastewater containing such solid organic matter to methane fermentation treatment with a raw material residence time (HRT) of 1 day or longer, 70% or more of the solid organic matter such as palm coconut shell can be converted into methane gas.

When subjecting palm oil wastewater generated from a palm oil factory to methane fermentation, the water temperature is not particularly limited, but is preferably 40 ° C. or higher. Maintaining the temperature of palm oil wastewater to be 40 ° C or higher and maintaining the temperature of organic wastewater in the endless water channel 11 at a high temperature around 55 ° C, the palm oil becomes solid and floats on the water surface. In addition, it can be prevented from adhering to the piping. Thereby, residual fats and oils can be efficiently converted into biogas. For example, 80% or more of the remaining fats and oils can be converted to methane gas by subjecting such organic wastewater to methane fermentation treatment with a raw material residence time (HRT) of 1 day or more.

Napiergrass is a perennial grass that grows fast and can be harvested 5 to 8 times a year in the tropics. Therefore, it attracts attention as a raw material for methane gas by methane fermentation. This napier grass can be mixed with waste water as a solid organic material raw material without being finely pulverized and subjected to methane fermentation treatment, and the amount of methane gas generated can be increased.

Even when methane fermentation treatment is applied to napier grass, the napier grass is mixed with waste water before being put into the endless water channel 11. The particle size of the napier glass is not particularly limited, but it is preferable to add after pulverizing to 50 mm or less. By setting the particle diameter of the napier glass to 50 mm or less, the fluidity can be improved to such an extent that the organic waste water containing the solid organic matter can be circulated in the endless water channel 11. For example, 70% or more of Napiergrass, which is a solid organic substance, can be converted to methane gas by subjecting the organic wastewater containing such a solid organic substance to a methane fermentation treatment with a raw material residence time (HRT) of 1 day or longer.

[Example 1]
In Example 1, the performance test of the methane fermentation treatment according to the present invention was performed using the cassava peel and the organic wastewater discharged from the cassava straw processing plant.

Cassava peel was mixed with organic wastewater without pretreatment. The cassava peel after mixing with the organic waste water included those having a particle size in the range of 10 to 50 mm.

A methane fermentation treatment system as shown in FIG. 2 was constructed as a prototype model of the methane fermentation treatment system. As the endless water channel 11 of this methane fermentation treatment system, one having two straight portions with a width of 110 mm, a depth of 400 mm (including a water depth of 200 mm), a total length of 800 mm, and a volume of 30 L was used. A stirrer was installed in the endless water channel 11. Further, four sheets of stainless steel plates having a longitudinal direction of 600 mm and a lateral direction of 250 mm, each having a polyethylene non-woven fabric attached to one straight portion of the endless water channel 11, were installed in parallel. At this time, the interval between the fixed beds 12 was 100 mm. The distance (installation height h) from the bottom of the endless water channel 11 to the lower end of the fixed floor 12 was set to 100 mm.

This prototype model is supplied with organic wastewater containing cassava peel obtained by mixing cassava peel and organic wastewater, and the organic wastewater containing this cassava peel is treated in an endless water channel 11 for a raw material retention time (HRT) of 5 days. did.

The amount of biogas recovered in this methane fermentation treatment system was about 1 NL / L-reactor / day, and the methane concentration was about 65%.

From the above results, the present methane fermentation treatment system can recover methane from waste water containing solid organic matter.

[Example 2]
A methane fermentation treatment system as shown in FIG. 2 was constructed as a prototype model of the methane fermentation treatment system. As the endless water channel 11 of this methane fermentation treatment system, one having two straight portions with a width of 2 m, a depth of 2.5 m (including a water depth of 2 m), a total length of 20 m and a volume of 100 m ³ was used. A stirrer was installed in the endless water channel 11. In addition, a fixed floor unit 12 ′ arranged side by side with four stainless steel plates with a non-woven fabric made of polyethylene attached to one straight portion of the endless water channel 11 as a fixed floor 12. Was provided. At this time, the interval between the fixed floor units 12 ′ was set to 500 mm.

In order to examine the influence of the distance (installation height h) from the bottom of the endless water channel 11 to the lower end of the fixed floor 12, in Example 2, the distance from the bottom of the endless water channel 11 to the lower end of the fixed floor 12 ( The test was performed by changing the installation height h) to 0 mm, 50 mm, 100 mm, 250 mm, and 500 mm. Using these prototype models, methane fermentation treatment was applied to palm oil mill wastewater as organic wastewater containing solid organic matter. As a pretreatment for the study, the load was adjusted by increasing the amount of palm oil mill wastewater supplied, and when the load was gradually increased and the residence time reached 10 days, the palm coconut shell crushed to 50 mm or less (dried) 10% by weight, and the supply of solid organic matter was started, and the operation was continued for 120 days thereafter.

As operating conditions, the temperature was maintained at 55 ° C., and the liquid in the reactor was circulated at a speed of 3 m / h. The flow velocity in the water channel was measured downstream of the current plate and controlled based on the measured value.

The average value of the height of the sediment immediately below the fixed bed (height from the bottom of the endless water channel 11 to the top of the sediment) was measured every 5 days for 120 days. When the fixed bed was buried in sediment, the depth of the sediment near the fixed bed was measured.

Fig. 9 shows the results of examination of the fixed floor installation height h and sediment height. In FIG. 9, the horizontal axis indicates the number of days from the start of the test, and the vertical axis indicates the height of the sediment immediately below the fixed bed. In FIG. 9, “the number of days from the start of the test” is defined as day 0 when the supply of the solid organic matter is started.

As shown in the graph of FIG. 9, it was found that the solid organic matter can be prevented from being deposited by keeping a space from the bottom of the endless water channel 11 to the lower end of the fixed bed. In particular, it has been found that the solid organic matter can be effectively prevented from being deposited by setting the interval (fixed floor installation height h) to 100 mm or more.

1a, 1b, 1c, 1d Methane fermentation treatment system 11, 11 ',

endless water channel

12, 12a, 12b Fixed bed 12', 12 "Fixed bed unit 100 Methane fermentation treatment equipment 121 Base material 122 Fixed part 13 Circulator 14 Re Dispersing device 15 Organic matter holding device 16 Solid matter decomposition tank 161 Discharge port 2 Storage tank 3 Mixing tank 4 Grinding device 5 Food processing factory L1, L2, L3 Liquid piping G1 Gas piping

Claims

A methane fermentation treatment system for treating organic wastewater containing solid organic matter with methane fermentation microorganisms for methane fermentation,
An endless water channel through which the organic wastewater circulates;
A plurality of fixed beds on which methane fermentation microorganisms are accumulated,
A methane fermentation treatment system, wherein a distance between adjacent fixed beds is 100 mm or more and 3000 mm or less.
The methane fermentation treatment system according to claim 1, wherein a lower end of the fixed floor is installed so as to have a height of 100 mm or more from a bottom of the endless water channel.
The methane fermentation treatment system according to claim 1, further comprising a redispersion device that redisperses the solid organic matter floating in the organic wastewater in the endless water channel.
The methane fermentation treatment system according to any one of claims 1 to 3, further comprising a heating device that heats and holds the temperature of the organic wastewater in the endless water channel at 50 ° C or higher and 65 ° C or lower.
The organic wastewater contains solubilized microorganisms,
5. The organic matter holding device which is formed by a net having a hole of 100 mm or less in the endless water channel and holds a solid organic substance having a particle size larger than the size of the hole inside. 5. The methane fermentation treatment system according to claim 1.
The organic wastewater contains solubilized microorganisms,
It has a solid matter decomposition tank that stores solid organic matter,
In the solid matter decomposition tank, the solid organic matter in the solid substance decomposition tank is dissolved by the organic wastewater containing the solubilized microorganisms supplied from the endless water channel, and the waste from the discharge port having a hole of 100 mm or less. The methane fermentation treatment system according to any one of claims 1 to 5, wherein the methane fermentation treatment system is discharged into a terminal water channel.
The methane fermentation treatment system according to any one of claims 1 to 6, wherein the suspended solid (SS) concentration of the organic wastewater is 1,000 mg / L or more.
A methane fermentation treatment method in which organic wastewater containing solid organic matter is treated with a methane fermentation microorganism group to methane fermentation,
A methane fermentation treatment method, comprising a plurality of fixed beds on which methane fermentation microorganisms are accumulated, and circulating the organic wastewater in an endless water channel having a distance between adjacent fixed beds of 100 mm or more and 3000 mm or less.
The organic wastewater contains solubilized microorganisms,
In the endless water channel, an organic substance holding device that is composed of a mesh body having holes with a size of 100 mm or less and holds solid organic substances having a particle size larger than the size of the holes is installed.
The methane fermentation treatment method according to claim 8, wherein the solid organic matter held in the organic matter holding device is dissolved along with the circulation of the organic wastewater in the endless water channel.
Solid organic matter is stored, a solid matter decomposition tank equipped with an outlet having a hole with a diameter of 100 mm or less is installed,
The methane fermentation according to claim 8 or 9, wherein the solid organic matter in the solid matter decomposition tank is dissolved by an organic wastewater containing solubilized microorganisms, and the solid organic matter is discharged from the discharge port into the endless water channel. Processing method.