JP5386112B2 - Organic waste treatment methods - Google Patents

Description

  The present invention relates to a method for treating organic waste, a method for producing biogas, and an organic waste treatment agent applied to them.

A system that recovers methane gas and reduces the amount of final waste by methane fermentation of solid organic waste containing protein such as garbage is being put into practical use for the formation of a recycling-oriented social system . Methane fermentation proceeds by methanogenic archaea such as the Methanosarcina genus (hereinafter referred to as Methanosarcina genus ), etc., but the bacteria are inhibited by the ammonia produced by the decomposition of proteins contained in organic waste. There is a problem. Therefore, a method of reducing the ammonia concentration to such an extent that water is added to organic waste and the methane fermentation by the bacteria is not hindered can be considered, but the amount of fermentation treatment becomes larger than the input amount of organic waste, and Since a water treatment facility is required after fermentation, there is a problem that the construction cost and the maintenance cost increase.

  On the other hand, Patent Document 1 discloses a technique for decomposing organic matter contained in organic waste using a hyperthermophilic anaerobic bacterium as a pretreatment for methane fermentation. Patent Document 1 also discloses that an ammonia recovery device is attached to equipment for decomposing organic matter. However, Patent Document 1 discloses characteristics of decomposing and solubilizing organic waste using a hyperthermophilic anaerobic bacterium, but does not disclose any specific examples of the superthermophilic anaerobic bacterium. Absent. Therefore, in the technique disclosed in Patent Document 1, it is unclear whether the hyperthermophilic anaerobic bacteria produce ammonia when decomposing and solubilizing organic waste.

  Patent Document 2 discloses that organic waste is solubilized to generate ammonia and hydrogen, the generated ammonia and hydrogen are removed, and the solubilized organic waste from which ammonia and hydrogen have been removed is subjected to methane fermentation treatment. The technique of doing is disclosed. In the technique disclosed in Patent Document 2, a temperature condition of 56 to 80 ° C. is adopted when solubilizing the organic waste, thereby disclosing a feature that is performed when the production rate of ammonia is increased. In addition, the technique disclosed in Patent Document 2 discloses the use of microorganisms that meet this temperature condition.

  However, as disclosed in Patent Documents 1 and 2, in order to decompose proteins and the like in organic waste, physical and chemical treatments such as high temperature and high pressure must be performed, and it is necessary to install a separate device. There was also a problem that the running cost was high.

JP2003-326237A JP 2006-205017 A

  Therefore, in view of the above problems, the present invention provides a method for treating organic waste, a method for producing biogas, and an organic property capable of converting nitrogen in an organic nitrogen compound contained in organic waste at a high concentration into ammonia. The purpose is to provide a waste treatment agent.

  In order to achieve the above-mentioned object, the present inventors conducted extensive research, and as a result, the intestinal bacterial culture producing protease and organic waste are brought into contact with each other and treated in an anaerobic environment. We have obtained knowledge that nitrogen in proteins contained in organic waste can be efficiently converted to ammonia. This invention is completed based on the said knowledge, and includes the following.

  The first invention of the present application includes an organic nitrogen compound decomposing step of bringing an intestinal bacterial culture producing protease into contact with organic waste and decomposing the organic nitrogen compound in the organic waste in an anaerobic environment. Provided is a method for treating organic waste. In the method for treating organic waste according to the present invention, anaerobic intestinal bacteria that produce protease and assimilate amino acids and peptides as carbon sources and energy sources are used. The protein component can be broken down into amino acids and ammonia can be produced by the same or different bacteria using the amino acids as carbon sources. Therefore, by using the organic waste processing method according to the present invention, the concentration of the ammonia component, which is one of the factors inhibiting methane fermentation, is maintained in a very low state in the subsequent methane fermentation process. be able to. Therefore, according to the organic waste processing method of the present invention, methane fermentation can be performed efficiently.

  The second invention of the present application includes an organic nitrogen compound decomposing step of contacting an intestinal bacterial culture producing protease with organic waste, and decomposing the organic nitrogen compound in the organic waste under an anaerobic environment; A biogas production method comprising: an ammonia separation step for separating an ammonia component produced by the organic nitrogen compound decomposition step; and a methane fermentation step for performing methane fermentation using the low nitrogen-containing organic waste after the ammonia separation step as a raw material I will provide a.

  3rd invention of this application provides the organic waste processing agent for decomposing | disassembling the organic nitrogen compound in organic waste containing the enteric bacteria which produce protease. In the organic waste treatment method and biogas production method described above, the organic waste treatment agent is brought into contact with the organic waste as an intestinal bacterial culture in the organic nitrogen compound decomposition step. The organic nitrogen compound in the organic waste in the decomposition step can be efficiently decomposed.

  Moreover, according to this invention, an organic waste processing system can be provided as the technical idea similar to the organic waste processing method mentioned above. That is, the organic waste treatment system according to the present invention includes an organic nitrogen compound decomposition tank that treats organic waste by intestinal bacteria that produce protease, and an organic waste treated in the organic nitrogen compound decomposition tank. An ammonia separation device that separates the ammonia component from the ammonia component, and a methane fermentation tank that performs methane fermentation using the low nitrogen-containing organic waste treated by the ammonia separation device as a raw material.

  Furthermore, according to the present invention, the organic waste treatment system described above further includes a biogas storage tank that collects and accumulates biogas mainly composed of methane generated in the methane fermentation tank. A system can be provided.

  Furthermore, according to this invention, the preparation method of the organic waste processing agent mentioned above can be provided.

  According to the organic waste treatment method of the present invention, nitrogen in the organic waste can be efficiently converted to ammonia. Moreover, according to the biogas production method of the present invention, methane fermentation can be stably performed when methane fermentation is performed using organic waste. Thereby, the biogas which has methane gas as a main component can be efficiently manufactured using organic waste. Furthermore, according to the organic waste treatment agent of the present invention, an intestinal bacterial culture capable of decomposing nitrogen oxides can be provided.

<Embodiment 1>
One embodiment of the present invention is an organic nitrogen compound decomposition in which an enteric bacterial culture producing protease is contacted with organic waste, and the organic nitrogen compound in the organic waste is decomposed in an anaerobic environment. It is the processing method of the organic waste including a process. Thus, an organic waste treatment system to which the present invention is applied is taken as an example, and the present embodiment will be described in detail below with reference to the drawings.

  FIG. 1 is an example of a system flow in an organic waste treatment system to which the present embodiment is applied. The organic waste treatment system shown in FIG. 1 includes an organic nitrogen compound decomposition tank 1, an ammonia separation device 2, and a methane fermentation tank 3. Among these, this embodiment is applied to the organic nitrogen compound decomposition tank 1. Therefore, the organic nitrogen compound decomposition tank 1 will be described in detail below. In this embodiment, the ammonia separation device 2 and the methane fermentation tank 3 are not essential components. For example, in the treatment of organic waste, when only the decomposition of the organic nitrogen compound in the organic waste is intended, the ammonia separation device 2 and the methane fermentation tank 3 are not necessary. These are necessary components in the second embodiment. Therefore, the ammonia separation device (2) and the methane fermentation tank 3 will be described in detail in Embodiment 2.

(Organic nitrogen compound decomposition tank)
“Organic nitrogen compound decomposition tank 1” refers to an organic nitrogen that decomposes an organic nitrogen compound in an organic waste in an anaerobic environment by bringing the intestinal bacterial culture producing protease into contact with the organic waste. It is a tank for performing a compound decomposition process. That is, in the organic nitrogen compound decomposition tank 1, the organic nitrogen compound in the organic waste is decomposed into amino acids by metabolism of enteric bacteria, and the amino acids are further converted into ammonia by the same enteric bacteria or other microorganisms. Is converted.

“Intestinal bacteria” are a group of bacteria that mainly live in the digestive tract of organisms, particularly in the intestines. Intestinal bacteria in the present invention refer to anaerobic bacteria (including obligate anaerobic bacteria and facultative anaerobic bacteria) having the ability to produce protease among the above enteric bacteria. Among them, the bacterium that can be cultured in a temperature range of 10 to 60 ° C. is preferable. Any such enteric bacterium can be used in the present invention without any particular limitation. For example, (referred to as less Bacillales) Bashiraresu th and / or Clostridia less th (hereinafter referred to as Clostridiales) (a Firmicutes below) Gram-positive bacteria Gate as bacteria such as belonging to the like. Further, specific examples (denoted as Entercoccus genus less) Enterococcus, (referred to as less Peptostreptococcus spp) Peptostreptococcus, (referred to as less Catonia genus) Katonia genus Weisera genus (hereinafter Weissella sp denoted And bacteria belonging to the genus Clostridium (hereinafter referred to as Clostridium ) and Tissierella (hereinafter referred to as Tissierella ) . More specifically, (1) 16S rRNA having the same sequence as the nucleotide sequence shown in SEQ ID NO: 1, or preferably 94% or more, more preferably 96% or more, and even more preferably 98% or more. (2) a sequence identical to the nucleotide sequence shown in SEQ ID NO: 2, or preferably 94% or more, more preferably 96% or more, and even more preferably 98% or more. A bacterium belonging to the genus Peptostreptococcus identified by 16S rRNA having (3) a sequence identical to the base sequence represented by SEQ ID NO: 3, or preferably 90% or more, more preferably 94% or more, and even more preferably 96% or more More preferably, a bacterium belonging to the genus Catonia specified by 16S rRNA having a sequence homology of 98% or more, (4) a sequence identical to the base sequence shown by SEQ ID NO: 4, or preferably 94% or more, more preferably More than 96%, even more Preferably, a bacterium belonging to the genus Weissella identified by 16S rRNA having a sequence homology of 98% or more, (5) a sequence identical to the base sequence shown by SEQ ID NO: 5, or preferably 94% or more, more preferably 96% More preferably, a bacterium belonging to the genus Clostridium identified by 16S rRNA having a sequence homology of 98% or more, (6) a sequence identical to the base sequence shown in SEQ ID NO: 6, or preferably 94% or more, more Preferably, bacteria belonging to the genus Clostridium identified by 16S rRNA having sequence homology of 96% or more, more preferably 98% or more, (7) the same sequence as the base sequence shown in SEQ ID NO: 7, or preferably 94 Examples include bacteria belonging to the genus Tissierella identified by 16S rRNA having a sequence homology of at least%, more preferably at least 96%, even more preferably at least 98%. Examples Specific examples of bacterial species with 16S rRNA of each sequence, the Enterococcus tie Randy box 993 strain for (1) (Entercoccus thailandicus strain 993 ), E. Akuimarinusu reference strain (E. aquimarinus type strain) (DSM : No.17690, CCUG: No.51308), E. Duransu the type strain (E. durans type strain) (DSM : No.20633, ATCC: No.19432), E. faecium type strain (E. faecium type strain) ( DSM: No.20477, ATCC: No.19434) or E. Foenikurikora reference strain (E. phoeniculicola type strain) (DSM : No.14726, ATCC: No.BAA-412), Peptostreptococcus for the (2) strike Mathis W2278 strain (Peptostreptococcus stomatis strain W2278) (DSM : No.17678, CCUG:. No 51858), Katonia Barunesae (Catonia barnesae) for the (3) (DSM: No.3244, ATCC: No.49795), For (4) above, Weisera Kivaria NRIC 0136 ( Weis sella cibaria NRIC 0136) or W. Kibaria reference strain (W. cibaria type strain) (DSM : No.15878, CCUG: No.41967), the Clostridium Soruderurii HT5 strain for (5) (Clostridium sordellii strain HT5 ) or C. Soruderurii reference strain (C. sordellii type strain) (DSM: No.2141, ATCC: No.9714), and Clostridium novyi NT strain (Clostridium novyi NT for the (6)) or C. novyi type strain (C. novyi type strain) (DSM : No .14992, ATCC: No. 17861).

  Any one of the enterobacteria used in the present invention may be used alone, or a plurality of enterobacteria may be used simultaneously or continuously in combination. The “living organism” may be a vertebrate or an invertebrate. However, vertebrates are preferred when the intestinal bacteria used in the present invention are collected from nature. This is because vertebrate intestinal bacteria can be adapted even under a high organic load environment, and are convenient for use under a high organic load environment such as organic waste. Domestic animals (for example, cows, pigs, sheep, chickens) and fish are more preferable because of the availability of internal organs including the intestines. Among them, fish is particularly preferable because it makes it easy to prepare all the intestinal bacteria listed above.

  The “intestinal bacterial culture” refers to a product obtained by culturing the enteric bacteria used in the present invention. Details of the intestinal bacterial culture and the preparation method will be described in detail in Embodiment 3, and the description thereof is omitted here.

  In the present invention, “contacting” refers to physically contacting the intestinal bacterial culture with organic waste. The contact method is not particularly limited as long as the contact can be achieved. For example, the contacting sequence may include intestinal bacterial culture being introduced into organic waste, organic waste being introduced into intestinal bacterial culture, or enteric bacterial culture and organic waste. Are also mixed at the same time. The contact form may be, for example, a liquid state such as a culture solution or a solid state such as a pellet made of a bacterial mass as long as it is on the intestinal bacterial culture side. On the organic waste side, any of a solid state obtained by pulverizing or crushing garbage, a semi-fluid state containing a large amount of water, a liquid state, or a mixed state thereof may be used. Intestinal bacterial cultures or vice versa, organic waste can also be added to the mixture of enteric bacterial culture and organic waste during the degradation process. Such additional addition is also convenient for controlling the decomposition of organic waste in the organic nitrogen compound decomposition step.

  The amount of intestinal bacterial culture used for contact varies depending on the type of organic waste and the amount of organic nitrogen compound contained in the organic waste. In general, there are various conventional bacteria in organic waste. Therefore, in order to efficiently decompose organic nitrogen compounds in organic waste and generate ammonia, it is necessary to use an amount of intestinal bacterial culture that can suppress the activity of these native bacteria. preferable. For example, the occupancy rate of the intestinal bacteria of the present invention in the bacterial flora in the organic waste may be at least 40% or more, preferably 60% or more, more preferably 80% or more.

  “Anaerobic” refers to a state where there is no oxygen or a state where the oxygen content is extremely low. This process is performed in an anaerobic environment. This is because the intestinal bacteria used in the present invention are anaerobic bacteria. That is, when the enteric bacterium used is an obligate anaerobic bacterium that cannot survive and grow in the presence of oxygen, it is necessary to make the inside of the organic nitrogen compound decomposition tank an “anaerobic environment”. Even if the enteric bacterium used is a facultative anaerobic bacterium that can survive in the presence of oxygen, it is present in organic waste by making the organic nitrogen compound decomposition tank an anaerobic environment. This is because the growth and activity of aerobic bacteria can be suppressed. In this step, the “anaerobic environment” can be achieved, for example, by removing the gas phase portion in the organic nitrogen compound decomposition tank or by replacing the gas phase portion with a gas not containing oxygen (for example, nitrogen gas). . The method of replacing the gas is a commonly used technique in the art as a gas exchange technique.

  The “organic waste” of the present invention refers to a waste containing an organic substance containing an organic nitrogen compound. Specific examples include, but are not limited to, fishery processing waste, fishery waste, garbage, municipal sewage sludge, food waste, livestock manure, and excess sewage sludge. As the organic waste according to the present invention, those discharged from a fish processing factory, fishing port, food factory and various factories can be used. In addition, the organic waste according to the present invention is appropriately subjected to pretreatment such as adjusting the moisture content, pretreatment such as pulverization to a desired size, etc. before applying to the organic waste treatment system according to the present invention. It may have been done.

  The “organic nitrogen compound” in the present invention refers to an organic compound having an amino group. For example, protein, its degradation product, peptide or amino acid is applicable. In this embodiment, proteins and peptides contained in organic waste are decomposed into amino acids by the intestinal bacteria of the present invention that produce protease, and the amino acids are organically decomposed by the same enteric bacteria or other microorganisms. Converted to acid and ammonia. The purpose is to decompose organic nitrogen compounds in organic waste by utilizing these reactions.

  In the organic waste treatment system according to the present invention, the organic nitrogen compound decomposition tank 1 has an internal temperature within the optimum temperature range and / or optimum pH of the proteolytic activity by proteases derived from enteric bacteria. It is preferable to control. For example, when the enteric bacteria exemplified above are used, the inside of the organic nitrogen compound decomposition tank 1 is 10 ° C to 60 ° C, preferably 20 ° C to 60 ° C, more preferably 20 ° C to 40 ° C, and still more preferably. The temperature is controlled in the range of 25 ° C to 35 ° C. The temperature is also the optimum culture temperature for the enteric bacteria used in the present invention. Also, the pH within the organic nitrogen compound decomposition increase 1 at the initial setting, that is, at the start of contact between the intestinal bacterial culture and the organic waste, is preferably pH 6.0 to pH 9.0, more preferably It is controlled to be in the range of pH 6.5 to pH 8.0, more preferably pH 7.0 to pH 7.5.

  As described above, the optimum temperature range of the organic nitrogen compound decomposition step in the present invention may be substantially within the normal temperature range. Moreover, the heat of decomposition accompanying the decomposition | disassembly of organic nitrogen compounds etc. and the heat of fermentation can also be utilized. Therefore, it is usually possible to maintain the optimum temperature without performing special heating control. Of course, you may heat as needed. In this case, the temperature control method and means of the organic nitrogen compound decomposition tank 1 are not particularly limited. For example, in the case of having a methane fermentation tank (3), the heat obtained when the methane gas generated in the methane fermentation tank 3 is used for cogeneration or the final treatment from the organic waste treatment system according to the present invention is used. The heat from the melting furnace, the combustion chamber and the boiler for treating the residual waste can be utilized. Although these melting furnaces, combustion chambers, and boilers are not shown in FIG. 1, these facilities can be attached to the organic waste treatment system according to the present invention. That is, the organic waste treatment system according to the present invention may include these melting furnaces, combustion chambers, and boilers. On the other hand, when the temperature of the organic waste exceeds the optimum temperature range due to the decomposition heat, heat is dissipated by a stirring means described later, or water or a buffer is contained in the organic nitrogen compound decomposition tank 1 as necessary. It is also possible to cool by adding.

  The pH control method and means of the organic nitrogen compound decomposition tank 1 are well-known techniques in the art and are not particularly limited. For example, when the inside of the organic nitrogen compound decomposition increase 1 is inclined to the acidic side from a predetermined pH, it can be adjusted by adding a sodium hydroxide solution or the like.

  The organic nitrogen compound decomposition tank 1 may have a stirring means. By stirring, the contact rate between the enteric bacteria in the tank and the organic waste is increased, and the decomposition efficiency of the organic nitrogen compound can be increased (that is, the generation rate of ammonia can be increased). The stirring means is not particularly limited as long as it can stir the substance in the tank. For example, in addition to a stirring device that has stirring blades and performs stirring by rotation thereof, a stirring device that shakes or rotates the organic nitrogen compound decomposition tank 1 itself may be mentioned.

  The treatment time in the organic nitrogen compound decomposition tank 1 varies depending on various factors such as the type of organic waste, the content of organic nitrogen compound, the amount of intestinal bacterial culture used, the treatment temperature, and the like. Accordingly, the processing time may be appropriately determined by those skilled in the art according to each element. In the present invention, it is preferable to treat until about 40%, more preferably about 60%, particularly preferably about 80% of nitrogen in the organic waste is converted to ammonia. This is because methane fermentation can be efficiently performed when the methane fermentation process is subsequently performed after this process.

  As described above, according to the organic nitrogen compound decomposition tank 1 of the present invention, protein components contained in organic waste are decomposed into amino acids or peptides by proteases derived from intestinal bacteria. The produced amino acid or peptide is assimilated by intestinal bacteria to produce fatty acid and ammonia. In other words, according to the organic nitrogen compound decomposition tank 1, the nitrogen content in the organic waste can be significantly reduced.

  Moreover, according to the organic waste processing method of the present invention, the organic nitrogen compound decomposition step can be performed at or near room temperature. Therefore, if the organic waste processing method of the present invention is used, it is not necessary to install a special device for performing physical or chemical processing such as high temperature and high pressure, and it is possible to reduce running costs. Become.

  When the treatment in the organic nitrogen compound decomposition tank 1 is finished, the occupation ratio of the intestinal bacteria of the present invention in the bacterial flora in the low nitrogen-containing organic waste containing high concentration of ammonia is preferably at least 40% or more, preferably If 60% or more, more preferably 80% or more, low-nitrogen-containing organic waste containing a high concentration of ammonia is not sent to the next process, leaving a part as a seed fungus. May be added to perform the organic nitrogen compound decomposition step.

<Embodiment 2>
Another embodiment of the present invention is an organic nitrogen compound decomposition in which an enteric bacterial culture producing protease is contacted with organic waste, and the organic nitrogen compound in the organic waste is decomposed in an anaerobic environment. A biogas including a process, an ammonia separation process for separating an ammonia component produced by the organic nitrogen compound decomposition process, and a methane fermentation process for performing methane fermentation using a low nitrogen-containing organic waste after the ammonia separation process as a raw material It is a manufacturing method. Therefore, a biogas production system to which the present invention is applied is taken as an example, and the present embodiment will be described in detail below with reference to the drawings.

  1 used in the description of the first embodiment can be an example of a system flow in the biogas production system to which the present embodiment is applied at the same time. The biogas production system shown in FIG. 1 includes an organic nitrogen compound decomposition tank 1, an ammonia separation device 2, and a methane fermentation tank 3. Moreover, although not described in FIG. 1, it is also possible to provide a methane storage tank that collects and accumulates biogas mainly composed of methane produced by methane fermentation in the methane fermentation tank 3. Among these, since the structure of the organic nitrogen compound decomposition tank 1 is the same as the said Embodiment 1, the description is abbreviate | omitted. Here, the ammonia separation device 2 and the methane fermentation tank 3, which are other essential configurations in the present embodiment, and the methane storage tank which is an additional configuration will be described.

(Ammonia separator)
The “ammonia separation device” 2 is a device for executing a step of separating the ammonia component generated in the organic nitrogen compound decomposition tank 1 and the low-nitrogen-containing organic waste. In other words, in the organic waste treatment system according to the present invention, as the low nitrogen-containing organic waste supplied to the methane fermentation tank 3, a low nitrogen-containing organic waste obtained by removing nitrogen contained in protein as ammonia is prepared. can do.

  The “ammonia component” refers to ammonia generated by the metabolic action of enteric bacteria used in the present invention in the organic nitrogen compound decomposition tank 1 and derivatives thereof.

  The method and means for removing the organic waste and the ammonia component are not limited at all, and conventionally known methods and apparatuses can be applied. For example, an ammonia stripping method, a method of adsorbing on a carrier, a method of converting ammonia to nitrogen using a chemical reaction, and the like can be mentioned. In the organic waste treatment system according to the present invention, the ammonia separation device 2 is a device for separating organic waste and ammonia by applying these methods.

  As the ammonia separation device 2 to which the ammonia stripping method is applied, a means for adjusting the pH of the organic waste after the treatment in the organic nitrogen compound decomposition tank 1 to the alkali side, and then a gas such as steam or air is supplied. Means. Ammonium ions contained in the organic waste are converted to ammonia by adjusting the pH to the alkali side and discharged into the gas phase by gas. Thus, according to the ammonia separation device 2, the ammonia component contained in the organic waste can be separated. The ammonia separation device 2 may include a recovery device that recovers the ammonia after the separation.

  As described above, the organic waste and ammonia can be separated, and as a result, the nitrogen content of the organic waste to be treated can be greatly reduced.

(Methane fermentation tank)
The “methane fermentation tank” 3 is a tank for executing a process of performing methane fermentation using the low nitrogen-containing organic waste after being processed by the ammonia separator 2 as a raw material.

  The organic waste supplied to the methane fermentation tank 3 contains lower fatty acids produced by intestinal bacteria from protein components through the series of steps described above. The lower fatty acid contained in the organic waste is used as it is as a substrate for methane fermentation by the methanogenic microorganism, or is used as a substrate for other microorganisms and converted into a substrate for methane fermentation by the methanogenic microorganism. Known methanogenic microorganisms are those using hydrogen and formic acid as substrates, or those using acetic acid as substrates. Thus, hydrogen, formic acid and acetic acid can be mentioned as substrates for methane fermentation.

Here, the methanogens, if a microorganism having a methane fermentation ability is not particularly limited, for example, bacteria and belonging to Methanobacterium genus (Methanobacterium sp), bacteria belonging to the meta knob Levi genus (Methanobrevibacter sp), Bacteria belonging to the genus Methanococcus (genus Methanococcus ) , bacteria belonging to the genus Methanomicrobium (genus Methanomicrobium ) , bacteria belonging to the genus Methanogenium ( genus Methanogenium ) , bacteria belonging to the genus Methanospirillum ( genus Methanospirillum ) , bacteria belonging to the genus Methanosarcina ( And acetic acid-assimilating methane-producing archaea) and bacteria belonging to the genus Methanosaeta (genus Methanosaeta ) (acetic acid-assimilating methane-producing archaea). In the organic waste treatment system according to the present invention, any of these methanogenic microorganisms may be used alone, or a plurality of types may be used in combination.

  Moreover, in the methane fermentation tank 3, microorganisms other than these methanogenic microorganisms may be growing. For example, a microorganism that metabolizes the lower fatty acid contained in the organic waste into a substance that can be used as a substrate for methane fermentation by the methanogenic microorganism may be grown in the methane fermentation tank 3.

  In the organic waste treatment system according to the present invention, the nitrogen content of the organic waste is greatly reduced by the above-described series of steps, so that the generation of ammonia that is a factor that inhibits the methane-producing microorganisms is greatly increased. Will be reduced. For this reason, methane fermentation by the methane-producing microorganisms proceeds stably and efficiently.

(Methane storage tank)
The biogas production system according to the present invention may include a methane storage tank for collecting biogas mainly composed of methane gas generated in the methane fermentation tank 3. The recovered biogas can be widely used as a substitute for petroleum. For example, biogas can be used as a compressed natural gas (CNG) and used for an internal combustion engine such as an automobile engine using CNG as fuel. The recovered biogas can also be used as fuel for a combined heat and power system (cogeneration system) that can supply heat and electricity simultaneously.

  As described above, since the biogas production system according to the present invention can stably and efficiently perform methane fermentation using organic waste as an initial raw material, circulation using organic waste effectively It is expected to be used as a social infrastructure. In addition, the organic waste processing system which concerns on this invention is not limited to the structure provided with the organic nitrogen compound decomposition tank (1), the ammonia separation apparatus 2, and the methane fermentation tank 3 as shown in FIG. The protease treatment by the intestinal bacteria described above, separation of the generated ammonia and organic waste, and methane fermentation can all be performed in the same tank. Moreover, the organic nitrogen compound decomposition tank 1, the ammonia separation apparatus 2, and the methane fermentation tank 3 may be installed in different places, respectively.

<Embodiment 3>
Another embodiment of the present invention is an organic waste treatment agent for decomposing organic nitrogen compounds in organic waste, including intestinal bacteria that produce protease.

  The organic waste treatment agent of this embodiment is synonymous with the intestinal bacterial culture used in Embodiment 1 or Embodiment 2. That is, the “organic waste treatment agent” refers to a product obtained by culturing the intestinal bacteria described in Embodiment 1 used in the present invention, like the intestinal bacteria culture. The term “product” as used herein mainly refers to enterobacteria, but may contain enzymes, physiologically active substances and / or metabolites produced by intestinal bacteria culture, and / or a medium. In addition, other bacteria that do not contribute to ammonia conversion of organic nitrogen oxides can be included. However, the bacterial flora in the organic waste treatment agent requires that the intestinal bacteria used in the present invention be in a dominant state. The form of the enteric bacteria culture is not particularly limited as long as at least 20%, preferably 40% or more, more preferably 60% or more, and even more preferably 80% or more of the enteric bacteria are in a living state. For example, it can be in a liquid state, a semi-fluid state, a solid state, or a combination thereof. Examples of the liquid state include a culture solution containing a medium itself, or a suspension obtained by separating intestinal bacteria once cultured from the medium by centrifugation or the like and then resuspending them in an appropriate buffer. Examples of the semi-fluid state include a mixture of enteric bacteria in a gel substance (for example, a thickening polysaccharide). Further, examples of the solid state include those in which enteric bacteria are adhered to a porous material such as charcoal, and those that are adhered to sawdust and fibers (for example, paper and cloth). Alternatively, a liquid or semi-solid intestinal bacterial culture can be packaged in a biodegradable capsule or the like.

  Enterobacteria can be obtained from nature or from manufacturers or deposited research institutions. When using enterobacteria purely cultured at a manufacturer or a depository research institution, it may be used as a single species as described above, or a plurality of species may be mixed and used at a ratio described in Table 2, for example. it can. The simplest method for obtaining is to collect from the intestines of livestock and fish.

  The preparation of the organic waste treatment agent, that is, the intestinal bacterial culture, can be achieved by inoculating the enteric bacteria of the present invention in a suitable medium and then culturing them under predetermined conditions for a predetermined time. The type and composition of the “medium” is not particularly limited as long as the intestinal bacteria of the present invention can grow. For example, a medium known in the art such as GAM medium (Nissui Pharmaceutical) can be used. Alternatively, a natural medium (for example, a viscera obtained by crushing a viscera using a mill or a food processor) may be used. The “predetermined time” is a time required for a sufficient amount of the intestinal bacteria used in the present invention to grow. Usually, it means the time until the enteric bacterium of the present invention reaches the logarithmic or stationary phase after the start of culture. This time varies depending on various requirements such as the type of intestinal bacteria to be cultured, the number of inoculated bacteria, and culture conditions (eg, temperature, pH, presence / absence of stirring). Therefore, the predetermined time may be appropriately determined by measuring by a technique well known to those skilled in the art based on these conditions. Further, the “predetermined condition” is a culture condition for preferentially culturing the intestinal bacteria used in the present invention. For example, as described above, a temperature range of 10 to 60 ° C. in an anaerobic environment and a pH range of pH 6.0 to pH 9.0 by default are applicable. As an example, a simple method for preparing the organic waste treatment agent of the present invention will be described below. First, the intestine containing intestinal bacteria collected from livestock, fish and the like or the internal organs containing the intestine are crushed. This is convenient because the enteric bacteria and natural medium used in the present invention can be obtained and prepared at the same time. Next, the visceral crushed material is put into the reactor, the gas phase portion is replaced with nitrogen gas, and placed in an anaerobic environment. Then, it adjusts to about pH7.0 and culture | cultivates, stirring for 1 to 2 weeks at 25 to 40 degreeC. After culturing, this culture solution may be used as the organic waste treatment agent of the present invention, or after centrifugation, a precipitate (pellet) excluding the liquid part may be used as the organic waste treatment agent.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the technical scope of this invention is not limited to a following example.

<Example 1>
(Purpose) To verify the effects of proteolysis and ammonia production by intestinal bacteria derived from fish viscera, mixing ratio, etc.

(material)
Enterobacteria: Natural fish enterobacteria were used. The fish residue obtained from the supermarket (Maruetsu) was selected from the visceral portion including mainly the intestines and minced with a meat mill.
・ Organic waste: The left rice (raw garbage) from the general canteen was crushed with a food processor.

(Method) 10: 0 (100% fish residue: base control), 8: 2 (80% fish residue), 6% so that the total amount of intestinal bacteria (fish residues) and organic waste is 50g, 6 : 4 (60% fish residue), 4: 6 (40% fish residue), 0:10 (0% fish residue: negative control) and mixed at 37 ° C for 3 days (no initial pH adjustment). Samples for analysis were sampled on the 0, 1, 2, and 3 days from each mixture. The NH ₄ —N concentration of each day was measured, and the amount of NH ₄ —N produced and the NH ₄ —N conversion rate were calculated.

(Results) The results are shown in FIG. Fig. 2a shows the NH ₄ -N concentration (ppm) in each mixed solution, and Fig. 2b shows the NH ₄ -N conversion rate in each mixed solution. Table 1 shows the amount of NH ₄ -N produced. From FIGS. 2a and 2b and Table 2, the NH ₄ —N conversion rate was highest when intestinal bacteria (fish residues) were mixed at 80%. The mixing ratio with waste was decided to be 8: 2.

<Example 2>
(Purpose) To verify the effects of proteolysis and ammonia production by intestinal bacterial cultures derived from fish viscera through continuous experiments.

(material)
Enterobacteriaceae culture: A fish residue obtained from a supermarket was selected from the visceral portion mainly containing the intestine and minced with meat miller. 8 L was charged into the reactor, the gas phase was exchanged with nitrogen gas, and then cultured at 37 ° C. with stirring. After 13 days, since the ammonia concentration in the culture broth became stable at a high concentration, this broth was used as an intestinal bacterial culture. The reactor had a volume of 12 L and had one stirring blade in the vertical direction, and this was continuously rotated at a constant speed of 10 rpm during the experiment.
・ Organic waste: The left rice (raw garbage) from the general canteen was crushed with a food processor.

(Method) 0.2 kg of organic waste food waste was mixed with 8 L of intestinal bacterial culture cultured for 13 days. Thereafter, 0.2 kg of organic waste decomposition products (reaction product of intestinal bacterial culture and organic waste) are withdrawn every day for 16 consecutive days. NH ₄ -N production amount, TN, and NH ₄ -N conversion rate (including 13 days of the bacterial culture preparation period) were calculated. In addition, since the contents overflowed due to gas accumulation in the reactor on the fourth day, the volume was changed to 7 L from the fourth day. The COD volumetric load is 11.6 CODcr-kg / m ³ · day from day 0 to day 4 of mixing, and 13.2 CODcr-kg / m ³ · day from day 4 to day 16 of mixing.

  (Results) The results are shown in FIG. Nitrogen derived from fish visceral protein could be converted to ammonia nitrogen by 70% or more by culturing intestinal bacteria naturally inhabiting the fish viscera for 13 days using the fish viscera as a medium. It was also found that this culture broth can be used as the intestinal bacterial culture of the present invention, and a high ammonia conversion rate of 60% or more can be maintained even after the organic waste (raw garbage) to be treated is charged.

<Example 3>
(Purpose) To verify the optimal temperature for proteolysis of intestinal bacteria derived from the internal organs of fish.

(Method) The internal organs of a plurality of fish were minced and mixed, and then adjusted to pH 7.0 with 10 mol / l NaOH. It was dispensed into 7 vials, N ₂ gas was inserted, and the vial was sealed to make the inside of the vial anaerobic. The culture temperature was set to 30, 35, 40, 45, 50, 55, and 60 ° C., respectively, and the cells were cultured for 7 days, and the amount of NH ₄ —N produced and the conversion rate were calculated.

(Results) The results are shown in FIG. In the 7-day culture, NH ₄ —N conversion was highest at 30 ° C., reaching 33%. Therefore, when intestinal bacteria derived from the viscera of fish were used, it was revealed that the optimum culture temperature was about 25 ° C. to 35 ° C. at an initial pH of 7.0.

<Example 4>
(Purpose) To verify the optimum pH for proteolysis of enteric bacteria derived from the internal organs of fish.

(Method) The viscera of a plurality of fish were minced and mixed, and then adjusted to pH 7.0, 7.5, 8.0, 8.5, and 9.0 with 10 mol / l NaOH. They were dispensed into vials, N ₂ gas was inserted and sealed, and the inside of the vial was made anaerobic. The culture temperature was set to 37 ° C. and the cells were cultured for 7 days, and the amount of NH ₄ —N produced and the conversion rate were calculated. A non-pH adjusted one was also prepared and cultured.

(Results) The results are shown in FIG. In the culture for 7 days, the NH ₄ -N conversion rate is the highest at 35% at pH 6.9 to 7.5 at the initial setting, and the optimal pH is 37 ° C when the intestinal bacteria derived from the internal organs of fish are used. The pH was about 6.9-7.5.

<Example 5>
(Objective) In order to identify the intestinal bacteria used in the present invention having the ability to decompose organic nitrogen compounds, the dominant bacteria in the intestinal bacterial culture of Example 2 were identified.

  (Method) A part of the culture solution on the 5th day after the start of preparation of the intestinal bacterial culture of Example 2 was collected, and the precipitate was collected by centrifugation, followed by DNA extraction based on a known technique. Subsequently, PCR targeting the bacterial 16S rRNA gene was performed using primers of EUB10F and UNIV1490R and subjected to cloning. About 50 cloning products were sequenced and bacterial species were identified from sequence homology. In addition, from Example 2, the intestinal bacteria that inhabit the intestinal bacterial culture can convert 70% or more of fish visceral protein-derived nitrogen into ammonia nitrogen, that is, produce protease. It has proven to be a bacterium that can subsequently convert degraded amino acids to ammonia.

  (Results) Table 2 shows the results. By culturing the internal organs of fish, it was confirmed that bacteria belonging to Firmicutes such as Bacillales and Closridiales predominate in the inoculum.

It is a schematic diagram which shows an example of the system flow in the organic waste processing system to which this invention is applied. It is a characteristic diagram showing the NH ₄ -N concentration (ppm) in a mixture of enteric bacteria culture and organic waste. Is a characteristic diagram showing NH ₄ -N conversion in the mixed solution of enteric bacteria culture and organic waste (%). It is a characteristic view which shows the effect of the proteolysis and ammonia production | generation by the enteric bacteria culture derived from the internal organs of a fish. It is a characteristic view which shows the relationship between the proteolysis and culture | cultivation temperature in enteric bacteria derived from the internal organs of fish. It is a characteristic view which shows the relationship between proteolysis and pH in enteric bacteria derived from the internal organs of fish.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Organic nitrogen compound decomposition tank 2 ... Ammonia separation device 3 ... Methane fermentation tank 4 ... Enterobacteria culture or organic waste processing agent

Claims (3)

Tissierella sp., Weissella cibaria, Peptostreptococcus stomatis, Catonia barnesae, and Enterococcus thailandicus selected from the group consisting of one or more Bring intestinal bacterial cultures into contact with organic waste and convert nitrogen in organic nitrogen compounds contained in organic waste to ammonia in an anaerobic environment at 20-40 ° C and pH 6.0-9.0 An organic waste treatment method including an organic nitrogen compound decomposition step. Contacting one or more intestinal bacterial cultures selected from the group consisting of Tisierella sp., Weisellakivaria, Peptostreptococcus stomatis, Catonia balnesae, and Enterococcus cylandix with organic waste, at 20-40 ° C and an organic nitrogen compound decomposition step of converting nitrogen in the organic nitrogen compound contained in the organic waste into ammonia in an anaerobic environment of pH 6.0 to 9.0;
An ammonia separation step of separating the ammonia component produced by the organic nitrogen compound decomposition step;
The biogas manufacturing method including the methane fermentation process which performs methane fermentation using the low nitrogen content organic waste after the said ammonia separation process as a raw material. An organic waste treatment agent comprising, as an active ingredient, a culture of at least one intestinal bacterium selected from the group consisting of Ticsiella sp, Weisella varia, Peptostreptococcus stomatis, Catonia varnesae, and Enterococcus cylandix .

Images