JP2007098228A - Method and apparatus for treatment of organic waste - Google Patents

Method and apparatus for treatment of organic waste Download PDF

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JP2007098228A
JP2007098228A JP2005289046A JP2005289046A JP2007098228A JP 2007098228 A JP2007098228 A JP 2007098228A JP 2005289046 A JP2005289046 A JP 2005289046A JP 2005289046 A JP2005289046 A JP 2005289046A JP 2007098228 A JP2007098228 A JP 2007098228A
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organic waste
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fermentation
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sludge
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JP4852954B2 (en
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Hoko Ryu
宝鋼 劉
Takero Misaki
岳郎 三崎
Tetsuro Fukase
哲朗 深瀬
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Kurita Water Industries Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

<P>PROBLEM TO BE SOLVED: To prevent ammonia inhibition during dry methane fermentation of an organic waste of a high total concentration of solid contents and a low C/N ratio. <P>SOLUTION: The feeding rate of an organic waste to a fermentation tank 25 for dry methane fermentation is reduced. More specifically, the organic waste is fed to the tank 25 so that organic matter in the organic waste is decomposed at a decomposition rate equal to or lower than 90% of the the maximum decomposition rate. Especially, the feeding rate of the organic waste is preferably adjusted so that the fermentation residue taken from the tank 25 is pH 8-9. A magnesium salt, is added, if necessary, so as to give a phosphorus content of ≥1 pt.mass and a magnesium content of ≥0.8 pt.mass to a content of ammonia-form nitrogen of 1 pt.mass in the mixture of the organic waste and dry methane sludge. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、有機性廃棄物をメタン発酵させる有機性廃棄物の処理方法に関し、特に、Ｃ／Ｎ比が２０以下で全固形物濃度が１５質量％以上である固形状の有機性廃棄物をメタン発酵させる乾式メタン発酵による有機性廃棄物の処理方法に関する。   The present invention relates to a method for treating organic waste in which organic waste is subjected to methane fermentation, and in particular, solid organic waste having a C / N ratio of 20 or less and a total solid concentration of 15% by mass or more. The present invention relates to a method for treating organic waste by dry methane fermentation for methane fermentation.

従来、有機性廃棄物をエネルギー源として利用する方法として、メタン発酵が知られている。近年ではメタンガスが新たなエネルギー源として注目されており、剪定枝、稲藁、および籾殻等の植物残渣、生ごみ、食品加工物残渣、並びに家畜糞尿等の固形状の有機性廃棄物からメタンガスを取り出す技術が注目されている。   Conventionally, methane fermentation is known as a method of using organic waste as an energy source. In recent years, methane gas has attracted attention as a new energy source. Methane gas is obtained from solid organic waste such as plant residues such as pruned branches, rice straw, and rice husks, garbage, food processing residue, and livestock manure. The technology to extract is drawing attention.

ここで、メタン発酵は、原料の有機性廃棄物の全固形物（ＴＳ）濃度により湿式メタン発酵と乾式メタン発酵とに大別される。湿式メタン発酵では、メタン細菌を含むメタン汚泥が液体中に浮遊した状態、または粒状に集積した状態で発酵槽内に保持され、有機性廃棄物は、ＴＳ濃度が４〜１０質量％程度の液状またはスラリ状で発酵槽に導入される。一方、乾式メタン発酵では、有機性廃棄物は、ＴＳ濃度が２５〜６０重量％程度というほぼ固体に近い状態で発酵槽に導入され、発酵槽内には、ＴＳ濃度が１５〜４０質量％程度の固形状のメタン汚泥（乾式メタン汚泥）が保持される。   Here, methane fermentation is roughly classified into wet methane fermentation and dry methane fermentation according to the total solid (TS) concentration of the raw organic waste. In wet methane fermentation, methane sludge containing methane bacteria is retained in a fermenter in a state where it is suspended in a liquid or in a state of being accumulated in a granular form, and organic waste is a liquid having a TS concentration of about 4 to 10% by mass. Or it is introduced into the fermenter in a slurry state. On the other hand, in the dry methane fermentation, the organic waste is introduced into the fermenter in a nearly solid state with a TS concentration of about 25 to 60% by weight, and the TS concentration is about 15 to 40% by mass in the fermenter. Solid methane sludge (dry methane sludge) is retained.

このように、乾式メタン発酵によれば固形状の有機性廃棄物をメタン発酵させることができる。このため、固形状有機性廃棄物を原料としてメタンガスを発生させる技術として、近年、乾式メタン発酵に注目が集まっている。   Thus, according to dry methane fermentation, solid organic waste can be methane-fermented. For this reason, in recent years, dry methane fermentation has attracted attention as a technique for generating methane gas using solid organic waste as a raw material.

ところで、固形状有機性廃棄物の中でも、生ごみ、食品加工物残渣、および家畜糞尿は蛋白質、すなわち有機態窒素を多く含み、Ｃ／Ｎ比（炭素／窒素の質量比）が２０以下と低い。このようにＣ／Ｎ比が低い有機性廃棄物（以下、「低Ｃ／Ｎ有機性廃棄物」）をメタン発酵すると、有機物が分解されてメタンガスが生成されると同時に、有機態窒素が分解されてアンモニア態窒素も生成される。   By the way, among solid organic waste, food waste, processed food residue, and livestock manure contain a large amount of protein, that is, organic nitrogen, and the C / N ratio (carbon / nitrogen mass ratio) is as low as 20 or less. . When organic waste with a low C / N ratio (hereinafter referred to as “low C / N organic waste”) is subjected to methane fermentation, organic matter is decomposed to produce methane gas, and organic nitrogen is decomposed at the same time. As a result, ammonia nitrogen is also produced.

メタン細菌の活性は、高濃度の遊離性のアンモニア態窒素により阻害され、メタン汚泥中のアンモニウム（ＮＨ４ ＋）濃度が２，５００ｍｇ／ｋｇ以上になると、メタン発酵活性が著しく阻害され、メタン発酵が停止することが知られている。このため、有機性廃棄物のメタン発酵処理においては、遊離性のアンモニア態窒素によるメタン発酵活性の阻害（以下、「アンモニア阻害」と略する）の防止は重要な技術課題であり、従来、アンモニア阻害を防止するための様々な方法が提案されている。 The activity of methane bacteria is inhibited by a high concentration of free ammonia nitrogen, and when the ammonium (NH 4 + ) concentration in methane sludge exceeds 2,500 mg / kg, the methane fermentation activity is significantly inhibited, and methane fermentation Is known to stop. Therefore, in the methane fermentation treatment of organic waste, prevention of inhibition of methane fermentation activity by free ammonia nitrogen (hereinafter abbreviated as “ammonia inhibition”) is an important technical issue. Various methods have been proposed to prevent inhibition.

例えば、有機性廃棄物を水で希釈する方法、酸素およびアンモニアを実質的に含まない気体を発酵槽内の混合物に通気することでアンモニアを気相に揮散させる方法が提案されている（特許文献１）。また、有機性廃棄物のＣ／Ｎ比を高くすることによりアンモニア阻害を回避する方法も知られている（例えば特許文献２）。さらに、発酵槽にマグネシウムおよびリンを添加することにより、リン酸マグネシウムアンモニウム（以下、「ＭＡＰ」）を生成させてアンモニアを不溶化させる方法も提案されている（例えば特許文献３）。
特開２００１−２７６８８０号公報 特開２００１−３４７２４７号公報 特開平７−５１６９３号公報 For example, a method of diluting organic waste with water and a method of volatilizing ammonia into the gas phase by passing a gas substantially free of oxygen and ammonia through a mixture in the fermenter have been proposed (Patent Literature). 1). A method for avoiding ammonia inhibition by increasing the C / N ratio of organic waste is also known (for example, Patent Document 2). Furthermore, a method has also been proposed in which magnesium and phosphorous are added to a fermenter to produce magnesium ammonium phosphate (hereinafter “MAP”) to insolubilize ammonia (for example, Patent Document 3).
JP 2001-276880 A JP 2001-347247 A Japanese Patent Laid-Open No. 7-51693

しかし、有機性廃棄物を水で希釈する方法ではメタン発酵残渣（以下、単に「発酵残渣」と省略する場合がある）から排出される排水量が多くなる。特に乾式メタン発酵の場合は水で希釈することにより発酵槽内のＴＳ濃度が低下して乾式メタン発酵ができなくなる場合もある。また、特許文献２に記載された方法は、湿式メタン発酵には適用できるが、乾式メタン発酵では、発酵槽内に保持される乾式メタン発酵汚泥はほぼ固形状であるため、十分な効果を得ることは困難である。   However, in the method of diluting organic waste with water, the amount of waste water discharged from the methane fermentation residue (hereinafter sometimes simply referred to as “fermentation residue”) increases. In particular, in the case of dry methane fermentation, dilution with water may reduce the TS concentration in the fermenter and make dry methane fermentation impossible. Moreover, although the method described in patent document 2 is applicable to wet methane fermentation, since dry methane fermentation sludge hold | maintained in a fermenter is substantially solid in dry methane fermentation, sufficient effect is acquired. It is difficult.

さらに、ＭＡＰは液体中では比較的容易に生成させることができるものの、乾式メタン発酵では発酵槽内の混合物がほぼ固体であるため、ＭＡＰを生成させることは容易ではない。このため、発酵槽に供給する有機性廃棄物にマグネシウム等を添加して窒素、リン、およびマグネシウムの濃度、並びにｐＨをＭＡＰ生成に適した条件としても必ずしもＭＡＰが生成されるとは限らない。また、特許文献３に記載された方法では、ＭＡＰを生成させるために発酵槽にｐＨ調整剤を添加する必要があり、ｐＨ調整剤の添加装置の設置および運転コストが発生する。   Furthermore, although MAP can be produced relatively easily in a liquid, it is not easy to produce MAP in dry methane fermentation because the mixture in the fermenter is almost solid. For this reason, MAP is not necessarily generated even if magnesium or the like is added to the organic waste to be supplied to the fermenter and the nitrogen, phosphorus, and magnesium concentrations and the pH are suitable for MAP generation. Moreover, in the method described in Patent Document 3, it is necessary to add a pH adjuster to the fermenter in order to generate MAP, which causes installation and operating costs of an apparatus for adding the pH adjuster.

このように、メタン発酵技術においては、アンモニア阻害を防止することは重要な技術課題であるが、従来提案されている方法では必ずしも満足できる結果を得られない場合もある。一方、乾式メタン発酵では湿式メタン発酵に比してアンモニア阻害が生じやすい。   As described above, in the methane fermentation technique, it is an important technical problem to prevent ammonia inhibition, but there are cases where satisfactory results cannot always be obtained by the conventionally proposed methods. On the other hand, ammonia inhibition is more likely to occur in dry methane fermentation than in wet methane fermentation.

すなわち、湿式メタン発酵では発酵槽に対する有機物負荷は２〜８ｋｇ−ＶＳ／ｍ３／日程度であるのに対し、乾式メタン発酵では発酵槽に対する有機物負荷は８〜１８ｋｇ−ＶＳｋｇ／ｍ３／日程度に達する。このため、そもそも乾式メタン発酵では湿式メタン発酵に比べて多くのアンモニア態窒素が生成されることとなる。 That is, in the wet methane fermentation, the organic load on the fermenter is about 2 to 8 kg-VS / m 3 / day, whereas in the dry methane fermentation, the organic load on the fermenter is about 8 to 18 kg-VS kg / m 3 / day. To reach. For this reason, in the first place, in dry methane fermentation, much ammonia nitrogen is produced | generated compared with wet methane fermentation.

例えば、蛋白質等の有機態窒素濃度が１０，０００ｍｇ／ｋｇ（湿重）の有機性廃棄物を有機物分解率５０％でメタン発酵させると、５，０００ｍｇ／ｋｇ（湿重）のアンモニア態窒素が発生する。発生したアンモニア態窒素のうち一部は微生物により消費されるが、およそ４，０００ｍｇ／ｋｇものアンモニア態窒素がメタン発酵中の汚泥に存在することになる。   For example, when organic waste such as protein having an organic nitrogen concentration of 10,000 mg / kg (wet weight) is subjected to methane fermentation at an organic matter decomposition rate of 50%, 5,000 mg / kg (wet weight) of ammonia nitrogen is produced. appear. Part of the generated ammonia nitrogen is consumed by microorganisms, but as much as 4,000 mg / kg of ammonia nitrogen is present in the sludge during methane fermentation.

さらに、湿式メタン発酵では、メタン発酵が液系で行われるため、メタン発酵過程で生成されるアンモニア態窒素は多くの液体で希釈される。一方、乾式メタン発酵では、原料有機物のＴＳ濃度が高いため、メタン発酵の過程で生成されたアンモニア態窒素は少量の水に溶解して濃縮された状態になると考えられる。このため、乾式メタン発酵では湿式メタン発酵に比してアンモニア阻害が生じやすく、中でもＣ／Ｎ比が２０以下の有機性廃棄物を被処理物とする場合はアンモニア阻害の問題が生じやすい。   Furthermore, in wet methane fermentation, since methane fermentation is performed in a liquid system, ammonia nitrogen produced in the methane fermentation process is diluted with many liquids. On the other hand, in dry methane fermentation, since the TS concentration of the raw material organic matter is high, it is considered that ammonia nitrogen produced in the process of methane fermentation is dissolved and concentrated in a small amount of water. For this reason, in dry methane fermentation, ammonia inhibition is more likely to occur than in wet methane fermentation, and in particular, when organic waste having a C / N ratio of 20 or less is used as an object to be treated, the problem of ammonia inhibition is likely to occur.

しかし、上述したとおり、乾式メタン発酵と湿式メタン発酵とでは特性が異なるため、湿式メタン発酵において有効なアンモニア阻害防止法であっても、乾式メタン発酵に適用できない場合も多い。   However, as described above, since characteristics differ between dry methane fermentation and wet methane fermentation, even an ammonia inhibition prevention method effective in wet methane fermentation is often not applicable to dry methane fermentation.

本発明は上記課題に鑑みてなされ、固形状の低Ｃ／Ｎ有機性廃棄物を乾式メタン発酵する際のアンモニア阻害を防止することを目的とする。特に、本発明は、ｐＨ調整剤や水等を有機性廃棄物に添加することなく、アンモニア阻害を防止できる乾式メタン発酵による有機性廃棄物の処理方法を提供することを目的とする。   This invention is made | formed in view of the said subject, and it aims at preventing ammonia inhibition at the time of dry-type methane fermentation of a solid low C / N organic waste. In particular, an object of the present invention is to provide a method for treating organic waste by dry methane fermentation that can prevent ammonia inhibition without adding a pH adjuster or water to the organic waste.

本発明者らは、乾式メタン発酵を行う発酵槽内への有機性廃棄物の供給速度を低下させ、発酵槽内での有機性廃棄物の滞留時間を長くすることでｐＨ調整剤等を添加することなく、アンモニア阻害を防止できることを見出し、本発明を完成させた。具体的には、本発明は、以下を提供する。   The present inventors added a pH adjuster etc. by lowering the supply rate of organic waste into the fermenter performing dry methane fermentation and increasing the residence time of the organic waste in the fermenter Thus, the present inventors have found that ammonia inhibition can be prevented without doing so. Specifically, the present invention provides the following.

（１） Ｃ／Ｎ比が２０以下で全固形物濃度１５質量％以上の固形状の有機性廃棄物と、全固形物濃度１５質量％以上の乾式メタン汚泥と、を混合して発酵槽において嫌気的条件下でメタン発酵させる有機性廃棄物の処理方法であって、 前記発酵槽での前記有機性廃棄物中の有機物の分解速度が、前記乾式メタン汚泥による前記有機性廃棄物中の有機物の最大分解速度の９０％以下となるように前記有機性廃棄物を前記発酵槽に供給してメタン発酵させる乾式メタン発酵工程を有する有機性廃棄物の処理方法。   (1) In a fermenter, a solid organic waste having a C / N ratio of 20 or less and a total solid concentration of 15% by mass or more and dry methane sludge having a total solids concentration of 15% by mass or more are mixed. A method for treating organic waste that is subjected to methane fermentation under anaerobic conditions, wherein the decomposition rate of the organic matter in the organic waste in the fermenter is organic matter in the organic waste by the dry methane sludge The organic waste processing method which has a dry-type methane fermentation process which supplies the said organic waste to the said fermenter so that it may become 90% or less of the maximum decomposition rate of methane, and is methane-fermented.

本発明は、全固形物濃度が１５質量％以上、特に２０〜４０質量％程度の固体または泥状（これらを「固形状」と総称する）であって、下記数式で表される乾物分解率が４０質量％以上の有機性廃棄物を処理対象とする乾式メタン発酵法である。本発明は、固形状有機性廃棄物の中でも、炭素（Ｃ）／窒素（Ｎ）の質量比が２０以下、好ましくは１８以下で、特に好ましくは３〜１２程度であって窒素含有量が多い固形状有機性廃棄物（固形状低Ｃ／Ｎ有機性廃棄物）を好適な処理対象とする。固形状低Ｃ／Ｎ有機性廃棄物の具体例としては、一般家庭およびレストラン等の事業所から排出される生ごみ、家畜糞尿、および食品加工産業に伴って排出される食品加工物残渣（以下、単に「食品残渣」と称する）が挙げられる。また、下水および屎尿処理等に伴って発生する有機性汚泥の脱水物（以下、「脱水ケーキ」）も本発明の処理対象としてよい。   The present invention is a solid or a mud with a total solid concentration of 15% by mass or more, particularly about 20 to 40% by mass (these are collectively referred to as “solid”), and is a dry matter decomposition rate represented by the following formula: Is a dry methane fermentation method for treating 40% by mass or more of organic waste. In the present invention, among solid organic wastes, the mass ratio of carbon (C) / nitrogen (N) is 20 or less, preferably 18 or less, particularly preferably about 3 to 12, and has a high nitrogen content. Solid organic waste (solid low C / N organic waste) is a suitable treatment target. Specific examples of solid low C / N organic waste include garbage, livestock manure, and food processing residue (hereinafter referred to as “food processing residue”) discharged from establishments such as households and restaurants. Simply referred to as “food residue”). Further, organic sludge dehydrated matter (hereinafter referred to as “dehydrated cake”) generated in connection with sewage and sewage treatment or the like may be the subject of the present invention.

Figure 2007098228
Figure 2007098228

乾式メタン発酵では、発酵原料である有機性廃棄物と混合されるメタン汚泥は、ＴＳ濃度が１５質量％以上、特に２５〜６０質量％程度で土塊状の乾式メタン汚泥である。乾式メタン汚泥には、メタン細菌がコロニー形成菌数（ＣＦＵ）として１０７〜９Ｎ／ｇ（乾重）程度含まれており、ＴＳ濃度が４〜１０質量％程度の湿式メタン汚泥に比して高い有機物負荷でメタン発酵を行うことができる。有機性廃棄物は、発酵槽の内部または／および外部で上記乾式メタン汚泥と混合され、嫌気的条件が維持される発酵槽内に所定時間保持されることにより、有機物がメタン細菌により分解されてメタンガスが生成される。 In dry methane fermentation, methane sludge mixed with organic waste, which is a fermentation raw material, is a dry methane sludge in the form of a lump with a TS concentration of 15% by mass or more, particularly about 25 to 60% by mass. Dry methane sludge contains about 10 7-9 N / g (dry weight) of methane bacteria as colony forming bacteria count (CFU), compared with wet methane sludge with a TS concentration of about 4-10 mass%. And methane fermentation with high organic load. Organic waste is mixed with the above-mentioned dry methane sludge inside or / and outside the fermenter and kept in the fermenter where anaerobic conditions are maintained for a predetermined time, so that organic matter is decomposed by methane bacteria. Methane gas is produced.

なお、本明細書において、「有機物」とは６００℃での強熱減量可能な炭素化合物を指し、「ＶＳ」と省略する場合がある。また、有機性廃棄物は、有機物以外に１〜３０質量％程度の無機物を含んでよい。   In this specification, “organic matter” refers to a carbon compound that can be reduced in ignition at 600 ° C., and may be abbreviated as “VS”. Moreover, organic waste may contain about 1-30 mass% inorganic substance other than organic substance.

本発明では、発酵槽におけるメタン発酵時の温度条件は特に限定されず、２０〜４０℃程度でメタン発酵させる中温メタン発酵としてもよく、あるいは、４５〜６０℃程度でメタン発酵させる高温メタン発酵としてもよい。高温メタン発酵は、発酵槽を小型化できるため好ましい。高温メタン発酵を行うためには、スチーム吹き込み装置等の加温手段を適宜、配置し、発酵槽に供給する有機性廃棄物を必要に応じて５０〜６５℃程度に加温するとよい。   In this invention, the temperature conditions at the time of methane fermentation in a fermenter are not specifically limited, It is good also as medium temperature methane fermentation to which methane fermentation is carried out at about 20-40 degreeC, or as high temperature methane fermentation to which methane fermentation is carried out at about 45-60 degreeC. Also good. High temperature methane fermentation is preferable because the fermenter can be downsized. In order to perform high-temperature methane fermentation, it is preferable to appropriately arrange heating means such as a steam blowing apparatus and to heat the organic waste to be supplied to the fermenter to about 50 to 65 ° C. as necessary.

従来の乾式メタン発酵では、有機性廃棄物中の有機物が最大分解速度で分解されるよう、発酵槽に対する有機性廃棄物の供給速度が設定されている。ここで、有機性廃棄物中の有機物の最大分解速度とは、所定量の有機性廃棄物を所定の有機物分解率（例えば５０〜６０質量％程度）までメタン発酵させるために要する時間（分解速度）が最短である分解速度のことであり、有機物の分解速度は、有機物濃度の単位時間当たりの変化量（ｄＶＳ／ｄｔ）で表される。最大分解速度は、酸生成菌、およびメタン生成細菌を含むメタン発酵に関与する細菌類（以下、「メタン発酵菌群」）が対数増殖する場合に得られ、有機物が不足するとメタン発酵菌群の増殖速度が低下して最大分解速度が得られない。   In the conventional dry methane fermentation, the supply rate of the organic waste to the fermenter is set so that the organic matter in the organic waste is decomposed at the maximum decomposition rate. Here, the maximum decomposition rate of organic matter in organic waste is the time required for methane fermentation of a predetermined amount of organic waste to a predetermined organic matter decomposition rate (for example, about 50 to 60% by mass) (decomposition rate). ) Is the shortest decomposition rate, and the decomposition rate of organic matter is represented by the amount of change (dVS / dt) per unit time of the concentration of organic matter. The maximum degradation rate is obtained when the acid-producing bacteria and bacteria involved in methane fermentation including the methanogenic bacteria (hereinafter referred to as “methane-fermenting fungal group”) grow logarithmically. The growth rate decreases and the maximum degradation rate cannot be obtained.

このため、従来は、最大分解速度が得られるように、発酵槽に対する有機性廃棄物の供給速度を高くしていた。これに対し、本発明は発酵槽に対する有機性廃棄物の供給速度を低くして、すなわち、発酵槽の単位容積あたりの有機性廃棄物の滞留時間を長くして、発酵槽において最大分解速度の９０％以下、好ましくは６０〜９０％の分解速度でメタン発酵が行われるようにする。   For this reason, conventionally, the supply rate of organic waste to the fermenter has been increased so as to obtain the maximum decomposition rate. In contrast, the present invention reduces the supply rate of organic waste to the fermenter, that is, increases the residence time of the organic waste per unit volume of the fermenter, and increases the maximum decomposition rate in the fermenter. The methane fermentation is performed at a decomposition rate of 90% or less, preferably 60 to 90%.

有機性廃棄物の最大分解速度は、有機性廃棄物の性状によっても異なるが、概ね、４〜１２ｋｇ−ＶＳ／ｍ３／日程度で、従来、発酵槽への有機性廃棄物の単位容積あたりの供給速度は、湿質で１５〜１５０ｋｇ／ｍ３／日程度である。これに対し本発明では、有機性廃棄物の発酵槽への単位容積あたりの供給速度は１３〜１３０ｋｇ／ｍ３／日程度とする。 Although the maximum decomposition rate of organic waste varies depending on the properties of the organic waste, it is generally about 4 to 12 kg-VS / m 3 / day, and conventionally, per unit volume of organic waste to the fermenter. Is about 15 to 150 kg / m 3 / day in terms of wetness. On the other hand, in this invention, the supply rate per unit volume to the fermenter of organic waste shall be about 13-130 kg / m < 3 > / day.

より具体的には、ＴＳ濃度が概ね２０〜３０質量％でＣ／Ｎ比が８〜１０程度の生ごみの場合、最大分解速度は８〜１０ｋｇ−ＶＳ／ｍ３／日程度で、従来、発酵槽への単位容積あたりの供給速度は、５５〜７０ｋｇ／ｍ３／日程度であるのに対し、本発明では３０〜６３ｋｇ／ｍ３／日程度とする。また、ＴＳ濃度が概ね５０〜６０質量％でＣ／Ｎ比が４〜１０程度の食品残渣の場合、最大分解速度は９〜１１ｋｇ−ＶＳ／ｍ３／日程度で、従来、発酵槽への単位容積あたりの供給速度は、１９〜２３ｋｇ／ｍ３／日程度であるのに対し、本発明では６〜２０ｋｇ／ｍ３／日程度とする。さらに、ＴＳ濃度が概ね２０〜３０質量％でＣ／Ｎ比が３〜８程度の家畜（牛・豚）糞尿の場合、最大分解速度は４〜６ｋｇ−ＶＳｋｇ／ｍ３／日程度で、従来、発酵槽への単位容積あたりの供給速度は、４０〜６０ｋｇ／ｍ３／日程度であるのに対し、本発明では２５〜５５ｋｇ／ｍ３／日程度とする。そして、ＴＳ濃度が概ね３０〜５０質量％でＣ／Ｎ比が８〜１５程度の鶏糞の場合、最大分解速度は５．５〜７．５ｋｇ−ＶＳ／ｍ３／日程度で、従来、発酵槽への単位容積あたりの供給速度は、３５〜５５ｋｇ／ｍ３／日程度であるのに対し、本発明では２０〜５０ｋｇ／ｍ３／日程度とする。なお、上記の発酵槽への供給速度は湿重としての値である。 More specifically, in the case of garbage with a TS concentration of about 20-30% by mass and a C / N ratio of about 8-10, the maximum decomposition rate is about 8-10 kg-VS / m 3 / day, The supply rate per unit volume to the fermenter is about 55 to 70 kg / m 3 / day, whereas in the present invention, it is about 30 to 63 kg / m 3 / day. Moreover, in the case of a food residue having a TS concentration of about 50 to 60% by mass and a C / N ratio of about 4 to 10, the maximum decomposition rate is about 9 to 11 kg-VS / m 3 / day. The supply rate per unit volume is about 19 to 23 kg / m 3 / day, whereas in the present invention, it is about 6 to 20 kg / m 3 / day. Furthermore, in the case of livestock (cattle / pig) manure with a TS concentration of about 20-30% by mass and a C / N ratio of about 3-8, the maximum degradation rate is about 4-6 kg-VS kg / m 3 / day. , feed rate per unit volume of the fermenter, while a 40~60kg / m 3 / day or so, in the present invention and 25~55kg / m 3 / day or so. And in the case of chicken manure having a TS concentration of approximately 30 to 50% by mass and a C / N ratio of approximately 8 to 15, the maximum decomposition rate is approximately 5.5 to 7.5 kg-VS / m 3 / day, and conventionally, fermentation The supply rate per unit volume to the tank is about 35 to 55 kg / m 3 / day, whereas in the present invention, it is about 20 to 50 kg / m 3 / day. In addition, the supply rate to said fermenter is a value as wet weight.

本発明では、このように発酵槽への有機性廃棄物の供給速度を低下させ、該有機性廃棄物の最大分解速度より１割以上低い分解速度で有機性廃棄物をメタン発酵させることにより、アンモニア阻害を防止する。   In the present invention, by reducing the supply rate of organic waste to the fermenter in this way, by subjecting the organic waste to methane fermentation at a decomposition rate that is 10% or less lower than the maximum decomposition rate of the organic waste, Prevent ammonia inhibition.

（２） 前記乾式メタン発酵工程において、前記発酵槽に導入された前記有機性廃棄物と前記乾式メタン汚泥との混合物のｐＨが８〜９の範囲となるように前記有機性廃棄物を前記発酵槽に供給する（１）に記載の有機性廃棄物の処理方法。   (2) In the dry methane fermentation step, the organic waste is fermented so that the pH of the mixture of the organic waste introduced into the fermenter and the dry methane sludge is in the range of 8-9. The processing method of the organic waste as described in (1) supplied to a tank.

乾式メタン発酵により有機性廃棄物を発酵させる場合の好適ｐＨは、従来は６〜８．５とされる。しかし、本発明者らは、発酵槽内にある固形状低Ｃ／Ｎ有機性廃棄物と乾式メタン発酵汚泥との混合物（以下、単に「混合物」と称する）のｐＨが８〜９となるように該有機性廃棄物を発酵槽に供給することで、該有機性廃棄物を最大分解速度より１割以上低い分解速度で乾式メタン発酵させ、アンモニア阻害をより効果的に防止できることを見出した。そこで、（２）記載の発明では、発酵槽内の混合物のｐＨが８〜９となるように固形状低Ｃ／Ｎ有機性廃棄物を発酵槽に供給する。   The preferred pH for fermenting organic waste by dry methane fermentation is conventionally 6 to 8.5. However, the present inventors set the pH of the mixture of solid low C / N organic waste and dry methane fermentation sludge (hereinafter simply referred to as “mixture”) in the fermenter to be 8-9. It was found that by supplying the organic waste to the fermentor, the organic waste was subjected to dry methane fermentation at a decomposition rate that is 10% or more lower than the maximum decomposition rate, and ammonia inhibition could be prevented more effectively. Then, in invention of (2) description, solid low C / N organic waste is supplied to a fermenter so that the pH of the mixture in a fermenter may be 8-9.

このようにｐＨを指標とすることで、発酵槽内にｐＨ計を設ける等して発酵槽内の混合物のｐＨを測定することにより、固形状低Ｃ／Ｎ有機性廃棄物の発酵槽への供給速度を容易に調整できる。このため本発明によれば、有機性廃棄物の処理装置を複雑化させることを回避して、固形状低Ｃ／Ｎ有機性廃棄物を、最大分解速度より１割以上低い分解速度で乾式メタン発酵させる状態を容易に維持し、アンモニア阻害を効果的に防止できる。   Thus, by using pH as an index, by measuring the pH of the mixture in the fermenter by providing a pH meter in the fermenter, the solid low C / N organic waste to the fermenter is measured. The supply speed can be easily adjusted. For this reason, according to the present invention, it is possible to avoid the complexity of the organic waste processing apparatus, and to convert the solid low C / N organic waste into dry methane at a decomposition rate lower than 10% from the maximum decomposition rate. The fermentation state can be easily maintained and ammonia inhibition can be effectively prevented.

なお、発酵槽内のｐＨ測定に代えて、発酵槽から排出される発酵残渣の残留有機酸（ＶＦＡ）を指標とし、発酵残渣中のＶＦＡ濃度が１，５００ｍｇ／ｋｇ（湿重）以下となるように固形状低Ｃ／Ｎ有機性廃棄物の供給速度を調整してもよい。   Instead of measuring the pH in the fermenter, the residual organic acid (VFA) of the fermentation residue discharged from the fermenter is used as an index, and the VFA concentration in the fermentation residue is 1,500 mg / kg (wet weight) or less. In this way, the supply rate of the solid low C / N organic waste may be adjusted.

（３） 前記有機性廃棄物と前記乾式メタン汚泥との混合物のアンモニア態窒素１質量部に対して、リンが１質量部以上、マグネシウムが０．８質量部以上となるようにして前記乾式メタン発酵工程を行う（１）または（２）に記載の有機性廃棄物の処理方法。   (3) With respect to 1 part by mass of ammonia nitrogen in the mixture of the organic waste and the dry methane sludge, phosphorus is 1 part by mass or more and magnesium is 0.8 part by mass or more. The processing method of the organic waste as described in (1) or (2) which performs a fermentation process.

本発明に従い、有機性廃棄物の分解速度を低く設定してメタン発酵を行うことにより、アンモニア阻害を防止できる理由は明らかではない。しかし、発酵槽内でＭＡＰが生成されることにより、アンモニア態窒素が不溶化されている可能性も考えられる。そこで、本発明ではＭＡＰの生成を促進するために、発酵槽に供給する固形状低Ｃ／Ｎ有機性廃棄物のアンモニア態窒素濃度、リン酸濃度、およびマグネシウム濃度を調整する。具体的には、固形状低Ｃ／Ｎ有機性廃棄物のアンモニア態窒素１モルに対し、リンおよびマグネシウムが共に０．５モル以上、好ましくは１モル程度となるよう調整する。   In accordance with the present invention, it is not clear why ammonia inhibition can be prevented by performing methane fermentation at a low organic waste decomposition rate. However, there is a possibility that ammonia nitrogen is insolubilized by generating MAP in the fermenter. Therefore, in the present invention, in order to promote the production of MAP, the ammonia nitrogen concentration, phosphoric acid concentration, and magnesium concentration of the solid low C / N organic waste supplied to the fermenter are adjusted. Specifically, it is adjusted so that both phosphorus and magnesium are 0.5 mol or more, preferably about 1 mol, with respect to 1 mol of ammonia nitrogen in the solid low C / N organic waste.

リンは、リン酸の形態で存在することが好ましく、固形状低Ｃ／Ｎ有機性廃棄物のリン酸およびマグネシウム濃度を上記範囲とするためには、酸化マグネシウムを含む土等をマグネシウム源として固形状低Ｃ／Ｎ有機性廃棄物、乾式メタン汚泥、およびこれらの混合物のいずれか１種以上に添加することが好ましい。また、ＭＡＰの粒子を種晶として固形状低Ｃ／Ｎ有機性廃棄物等に添加してもよい。リン酸濃度については、固形状低Ｃ／Ｎ有機性廃棄物のメタン発酵の進行に伴ってリン酸が生成されるため、リン酸源については添加しなくてもよいが、リン酸が不足する場合は、液体のオルトリン酸（Ｈ３ＰＯ４）等をリン酸源として添加すればよい。 Phosphorus is preferably present in the form of phosphoric acid. In order to make the phosphoric acid and magnesium concentration of the solid low C / N organic waste within the above range, solid containing magnesium oxide as a magnesium source is used as a solid source. Preferably, it is added to any one or more of low C / N organic waste, dry methane sludge, and mixtures thereof. Alternatively, MAP particles may be added as seed crystals to solid low C / N organic waste or the like. Regarding the phosphoric acid concentration, phosphoric acid is generated with the progress of methane fermentation of solid low C / N organic waste, so it is not necessary to add a phosphoric acid source, but phosphoric acid is insufficient. In this case, liquid orthophosphoric acid (H 3 PO 4 ) or the like may be added as a phosphoric acid source.

（４） Ｃ／Ｎ比が２０以下で全固形物濃度１５質量％以上の固形状の有機性廃棄物が導入され、全固形物濃度１５質量％以上の乾式メタン汚泥と該有機性廃棄物が混合された状態でメタン発酵が行われる発酵槽を有する有機性廃棄物の処理装置であって、 前記発酵槽は、該発酵槽での前記有機性廃棄物中の有機物の分解速度が、前記乾式メタン汚泥による前記有機性廃棄物中の有機物の最大分解速度の９０％以下となるように前記有機性廃棄物を該発酵槽に供給できる容積を有する有機性廃棄物の処理装置。   (4) Solid organic waste having a C / N ratio of 20 or less and a total solid concentration of 15% by mass or more is introduced, and dry methane sludge having a total solid concentration of 15% by mass or more and the organic waste are An organic waste processing apparatus having a fermenter in which methane fermentation is performed in a mixed state, wherein the fermenter has a decomposition rate of organic matter in the organic waste in the fermenter, the dry type An organic waste processing apparatus having a volume capable of supplying the organic waste to the fermenter so that the maximum decomposition rate of organic matter in the organic waste by methane sludge is 90% or less.

本発明では、発酵槽に対する有機性廃棄物の供給速度が低く、発酵槽内での有機性廃棄物の滞留時間が長くなるため、従来法と同量の有機性廃棄物をメタン発酵させる場合は、従来法を行う場合に比して発酵槽を大きくする必要がある。具体的には、発酵槽での有機性廃棄物の分解速度を、最大分解速度の９０％以下となるように有機性廃棄物を発酵槽に供給した場合でも、発酵槽内に供給された有機性廃棄物の有機物分解率が所定値、例えば５０質量％となるまで、発酵槽内に有機性廃棄物を保持することができる大きさとする。   In the present invention, the supply rate of organic waste to the fermenter is low, and the residence time of the organic waste in the fermenter is long. Therefore, when methane fermentation of the same amount of organic waste as in the conventional method is performed, It is necessary to enlarge the fermenter as compared with the conventional method. Specifically, even when the organic waste is supplied to the fermentor so that the decomposition rate of the organic waste in the fermenter is 90% or less of the maximum decomposition rate, the organic supplied to the fermenter Until the organic matter decomposition rate of the organic waste reaches a predetermined value, for example, 50% by mass, the organic waste is set to a size that can be retained in the fermenter.

（５） 前記発酵槽は、該発酵槽内に保持される前記乾式メタン汚泥と前記有機性廃棄物との混合物のｐＨを計測するｐＨ計を備え、 前記混合物のｐＨが８〜９となるように、前記発酵槽に対する前記有機性廃棄物の供給速度を調整する供給制御手段をさらに有する（４）に記載の有機性廃棄物の処理装置。   (5) The fermenter includes a pH meter that measures the pH of the mixture of the dry methane sludge and the organic waste held in the fermenter, so that the pH of the mixture is 8-9. The organic waste processing apparatus according to (4), further comprising supply control means for adjusting a supply speed of the organic waste to the fermenter.

本発明では、発酵槽内にｐＨ計を設けることで、容易に固形状低Ｃ／Ｎ有機性廃棄物の供給速度を調整できる。   In the present invention, the supply rate of the solid low C / N organic waste can be easily adjusted by providing a pH meter in the fermenter.

本発明によれば、Ｃ／Ｎ比が低く、ＴＳ濃度が高い固形状の有機性廃棄物のメタン発酵処理において、簡易にアンモニア阻害を防止できる。   According to the present invention, ammonia inhibition can be easily prevented in the methane fermentation treatment of solid organic waste having a low C / N ratio and a high TS concentration.

以下、本発明について図面を用いて詳細に説明する。図１は、本発明の一実施形態に係る有機性廃棄物の処理装置１１の模式図である。処理装置１１は、有機性廃棄物を一時的に貯留する貯留槽２１、混合装置２３、および発酵槽２５を備える。混合装置２３と発酵槽２５とは導入路３３および汚泥返送路３６で接続され、有機性廃棄物は発酵槽２５から返送された乾式メタン汚泥と発酵槽２５外で混合されてから、発酵槽２５に供給されるよう、構成されている。   Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view of an organic waste processing apparatus 11 according to an embodiment of the present invention. The processing apparatus 11 includes a storage tank 21 that temporarily stores organic waste, a mixing apparatus 23, and a fermentation tank 25. The mixing device 23 and the fermenter 25 are connected by an introduction path 33 and a sludge return path 36, and the organic waste is mixed with the dry methane sludge returned from the fermenter 25 and outside the fermenter 25, and then the fermenter 25. It is comprised so that it may be supplied to.

このように、発酵槽２５外で乾式メタン汚泥と有機性廃棄物とを混合する構成にすれば、有機性廃棄物のＴＳ濃度が３０〜７０質量％程度、乾式メタン汚泥のＴＳ濃度が１５〜５０質量％程度である場合でも、希釈水を加えることなく、有機性廃棄物と乾式メタン汚泥とを混合でき、発酵槽２５内を嫌気的条件に維持することも容易となる。ただし、本発明は、発酵槽２５の内部に攪拌手段を設けることにより、発酵槽２５内部で有機性廃棄物と乾式メタン汚泥とを混合する方法を排除しない。   Thus, if it is set as the structure which mixes dry methane sludge and organic waste outside the fermenter 25, TS density | concentration of organic waste will be about 30-70 mass%, and TS density | concentration of dry methane sludge will be 15-. Even in the case of about 50% by mass, the organic waste and the dry methane sludge can be mixed without adding dilution water, and the inside of the fermenter 25 can be easily maintained under anaerobic conditions. However, the present invention does not exclude a method of mixing organic waste and dry methane sludge inside the fermenter 25 by providing a stirring means inside the fermenter 25.

なお、汚泥返送路３６の一端縁は、混合装置２３と発酵槽２５との間に接続してもよく、例えば導入路３３の途中に設けた攪拌手段を備える投入ポンプＰに接続してもよい。   In addition, the one end edge of the sludge return path 36 may be connected between the mixing apparatus 23 and the fermenter 25, for example, may be connected to the input pump P provided with the stirring means provided in the middle of the introduction path 33. .

処理装置１１は、４５〜６０℃の高温メタン発酵を行う装置として構成され、混合装置２３には、有機性廃棄物を加温するための加温手段２４が接続されている。加温手段２４は特に限定されず、例えば有機性廃棄物にスチームを吹き込むことにより、有機性廃棄物を直接的に加温する装置、または、混合装置を加温することで有機性廃棄物を間接的に加温する構成としてもよい。なお、高温メタン発酵に代えて中温メタン発酵を行う場合は、加温手段２４を省略してもよい。   The processing device 11 is configured as a device that performs high-temperature methane fermentation at 45 to 60 ° C., and the mixing device 23 is connected to a heating means 24 for heating the organic waste. The heating means 24 is not particularly limited. For example, by blowing steam into the organic waste, the organic waste is directly heated, or the organic waste is heated by heating the mixing device. It is good also as a structure heated indirectly. In addition, when replacing with high temperature methane fermentation and performing medium temperature methane fermentation, you may abbreviate | omit the heating means 24. FIG.

発酵槽２５には排泥路３５とガス路３７とがさらに接続されており、発酵槽２５内でメタン発酵が進んだ混合物は、発酵残渣として排泥路３５から取り出される。排泥路３５の途中には、汚泥返送路３６が接続されており、発酵残渣の一部は汚泥返送路３６を介して返送汚泥として混合装置２３に送られる。排泥路３５は、堆肥化装置２９Ａと接続されており、返送汚泥として利用されない発酵残渣を原料として堆肥を製造できるように構成されている。   A waste mud passage 35 and a gas passage 37 are further connected to the fermenter 25, and the mixture that has undergone methane fermentation in the fermenter 25 is taken out from the waste mud passage 35 as a fermentation residue. A sludge return path 36 is connected in the middle of the sludge discharge path 35, and a part of the fermentation residue is sent to the mixing device 23 through the sludge return path 36 as return sludge. The waste mud passage 35 is connected to the composting device 29A, and is configured to be able to produce compost using a fermentation residue that is not used as return sludge.

処理装置１１は、発酵残渣を堆肥原料として利用できるように構成されているが、発酵残渣は炭化物原料とすることもできる。発酵残渣から炭化物を製造する場合は、堆肥化装置２９Ａに代えて、排泥路３５を介して炭化装置２９Ｂを発酵槽２５の後段に配置すればよい。また、排泥路３５を分岐させて、堆肥化装置２９Ａと炭化装置２９Ｂとを設ければ、発酵残渣を原料として、堆肥および炭化物のどちらかまたは両方を適宜、製造できる。   Although the processing apparatus 11 is comprised so that a fermentation residue can be utilized as a compost raw material, a fermentation residue can also be used as a carbide raw material. In the case of producing a carbide from the fermentation residue, the carbonization device 29B may be disposed at the rear stage of the fermenter 25 via the mud passage 35 instead of the composting device 29A. Further, if the waste mud passage 35 is branched and the composting device 29A and the carbonization device 29B are provided, either or both of compost and carbide can be appropriately produced using the fermentation residue as a raw material.

ガス路３７は、メタンガスをエネルギー源として発電を行う発電装置２７と接続されている。発電装置２７は、破線で示した廃熱路３８を介して堆肥化装置２９Ａ、炭化装置２９Ｂ、および混合装置２３の加温手段２４のいずれか１以上の機器と接続することが好ましい。かかる構成により、堆肥化装置２９Ａ、炭化装置２９Ｂおよび加温手段２４のいずれか１以上の機器の熱源として、発電装置２７の廃熱を利用できる。   The gas path 37 is connected to a power generation device 27 that generates power using methane gas as an energy source. The power generation device 27 is preferably connected to one or more devices of the composting device 29A, the carbonization device 29B, and the heating means 24 of the mixing device 23 via a waste heat path 38 indicated by a broken line. With this configuration, the waste heat of the power generation device 27 can be used as a heat source for any one or more of the composting device 29A, the carbonization device 29B, and the heating means 24.

次に、上記処理装置１１を用いた有機性廃棄物の処理方法について説明する。本発明では、Ｃ／Ｎ比が２０以下、ＴＳ濃度が１５質量％以上の固形状低Ｃ／Ｎ有機性廃棄物を原料としてメタン発酵を行う。以下、本発明で処理するメタン発酵原料を「発酵原料」と称する。   Next, the organic waste processing method using the processing apparatus 11 will be described. In the present invention, methane fermentation is performed using a solid low C / N organic waste having a C / N ratio of 20 or less and a TS concentration of 15% by mass or more as a raw material. Hereinafter, the methane fermentation raw material treated in the present invention is referred to as “fermentation raw material”.

まず、メタン発酵工程に先立ち、既存のメタン発酵槽から採取されたメタン汚泥等を種汚泥として発酵原料の供給量を徐々に増大させる立ち上げ工程を実施する。立ち上げ工程とは、乾式、または湿式を問わず、メタン発酵を行う既存のメタン発酵処理装置の発酵槽に保持されたメタン細菌を含む汚泥（メタン汚泥）を種汚泥とし、種汚泥を馴養することにより、ＴＳ濃度や菌相が発酵原料の性状に適した乾式メタン汚泥を得る工程である。   First, prior to the methane fermentation process, a start-up process for gradually increasing the supply amount of fermentation raw materials using methane sludge collected from an existing methane fermentation tank as seed sludge is performed. The start-up process, regardless of whether it is dry or wet, uses sludge containing methane bacteria (methane sludge) held in the fermenter of the existing methane fermentation treatment equipment that performs methane fermentation as seed sludge and acclimatizes the seed sludge This is a process for obtaining dry methane sludge in which the TS concentration and the microflora are suitable for the properties of the fermentation raw material.

具体的には、立ち上げ工程では処理対象とする有機性廃棄物を種汚泥と混合して、有機性廃棄物の供給量を徐々に増加させる。このように、有機性廃棄物の供給量を増大させると、供給量の増大に伴ってメタンガスの発生量が指数関数的に増大するが、供給量がある一定量を超えると、メタンガスの発生量の増大が鈍化する。有機性廃棄物の最大分解速度は、このようにメタンガスの発生量の増大が鈍化する付近での分解速度である。   Specifically, in the start-up process, organic waste to be treated is mixed with seed sludge, and the supply amount of organic waste is gradually increased. Thus, when the supply amount of organic waste is increased, the amount of methane gas generated increases exponentially with the increase of the supply amount, but when the supply amount exceeds a certain amount, the amount of methane gas generated is increased. The increase in growth slows down. The maximum decomposition rate of organic waste is the decomposition rate near the increase in the amount of methane gas generated in this way.

本発明のメタン発酵工程は、有機性廃棄物の供給量を徐々に増大させる立ち上げ工程において、最大分解速度が得られた時点で立ち上げ工程を終了し、最大分解速度での有機性廃棄物のメタン発酵処理が可能となって以降行うものである。このように、メタン発酵工程に先立ち、立ち上げ工程を行って処理対象の有機性廃棄物に適した性状で、該有機性廃棄物の最大分解速度での処理が可能な乾式メタン汚泥を調整することで、メタン発酵工程での処理を安定して行うことができる。   The methane fermentation process of the present invention is a start-up process in which the supply amount of organic waste is gradually increased. When the maximum decomposition rate is obtained, the start-up process is terminated, and the organic waste at the maximum decomposition rate is obtained. The methane fermentation treatment is possible and is performed thereafter. Thus, prior to the methane fermentation process, the start-up process is performed to adjust the dry methane sludge that is suitable for the organic waste to be treated and can be treated at the maximum decomposition rate of the organic waste. Thereby, the process in a methane fermentation process can be performed stably.

メタン発酵工程は、かかる立ち上げ工程を終了した後、開始する。具体的には、まず、発酵槽２５への供給量を調整するために発酵原料を貯留槽２１に一時的に貯留し、移送路３１またはパワーショベル等の移送手段を介して発酵原料を貯留槽２１から混合装置２３に供給する。混合装置２３では、加温手段２４により発酵原料を３０〜６５℃程度に加温するとともに、立ち上げ工程で得られた乾式メタン汚泥を返送汚泥として汚泥返送路３６から供給し、加温された発酵原料と混合する。混合装置２３で得られた発酵原料と乾式メタン汚泥との混合物は、導入路３３から発酵槽２５に投入する。   The methane fermentation process starts after the start-up process is completed. Specifically, first, the fermentation raw material is temporarily stored in the storage tank 21 in order to adjust the supply amount to the fermentation tank 25, and the fermentation raw material is stored in the storage tank via transfer means 31 or a transfer means such as a power shovel. 21 to the mixing device 23. In the mixing apparatus 23, while heating the fermentation raw material to about 30-65 degreeC with the heating means 24, the dry-type methane sludge obtained at the starting process was supplied from the sludge return path 36 as return sludge, and was heated. Mix with fermentation ingredients. The mixture of the fermentation raw material and dry methane sludge obtained by the mixing device 23 is introduced into the fermentation tank 25 from the introduction path 33.

混合装置２３または導入路３３には土等のマグネシウム源を添加するＭＡＰ成分添加装置（図示せず）を必要に応じて接続し、混合物のアンモニア態窒素：リン：マグネシウムのモル比を１：１：１とすることが好ましい。また、ＭＡＰの生成を促進するために、発酵原料および混合物のいずれか一方または両方にＭＡＰの種晶を添加してもよい。ＭＡＰの種晶の添加量は、混合物に対して０．０１〜１質量％（乾重）とするとよい。混合物にＭＡＰの種晶を添加することで、アンモニア阻害防止効果を安定して発揮させるまでに要する期間を短縮できる。   A MAP component addition device (not shown) for adding a magnesium source such as soil is connected to the mixing device 23 or the introduction path 33 as necessary, and the molar ratio of ammonia nitrogen: phosphorus: magnesium in the mixture is 1: 1. : 1 is preferable. Moreover, in order to accelerate | stimulate the production | generation of MAP, you may add the seed crystal | crystallization of MAP to either one or both of a fermentation raw material and a mixture. The addition amount of the MAP seed crystal is preferably 0.01 to 1% by mass (dry weight) with respect to the mixture. By adding MAP seed crystals to the mixture, it is possible to shorten the time required to stably exhibit the ammonia inhibition preventing effect.

混合物は、発酵槽２５における発酵原料の最大分解速度の９割以下、好ましくは６〜９割の分解速度で発酵原料のメタン発酵を完成させるように発酵槽２５に供給する。具体的には、発酵槽２５に対する有機物負荷を１日あたり５〜１６ｋｇ−ＶＳ／ｍ３／日程度、発酵原料の発酵槽２５内での滞留時間が１８〜５０日程度となるように混合物を供給すればよい。発酵原料の分解速度をかかる範囲とするためには、発酵槽２５に対する混合物の供給速度を調整してもよく、発酵槽２５の容積を調整してもよい。 The mixture is supplied to the fermenter 25 so as to complete methane fermentation of the fermented raw material at a decomposition rate of 90% or less, preferably 60 to 90% of the maximum decomposition rate of the fermentation raw material in the fermenter 25. Specifically, the organic substance load on the fermenter 25 is about 5 to 16 kg-VS / m 3 / day per day, and the mixture is set so that the residence time of the fermentation raw material in the fermenter 25 is about 18 to 50 days. What is necessary is just to supply. In order to set the decomposition rate of the fermentation raw material within such a range, the supply rate of the mixture to the fermenter 25 may be adjusted, or the volume of the fermenter 25 may be adjusted.

また、発酵槽２５または排泥路３５にｐＨ計ＰＨを取り付けることにより、発酵槽２５内の混合物または発酵残渣のｐＨを測定して、混合物または発酵残渣のｐＨが８〜９となるように発酵原料の供給速度を調整してもよい。さらに、発酵残渣のＶＦＡ濃度を測定し、ＶＦＡ濃度が１，５００ｍｇ／ｋｇ以下となるように発酵原料の供給速度を調整してもよい。   Further, by attaching a pH meter PH to the fermenter 25 or the waste mud passage 35, the pH of the mixture or fermentation residue in the fermenter 25 is measured, and fermentation is performed so that the pH of the mixture or fermentation residue becomes 8-9. The feed rate of the raw material may be adjusted. Furthermore, you may measure the VFA density | concentration of a fermentation residue and adjust the supply speed | rate of a fermentation raw material so that VFA density | concentration may be 1500 mg / kg or less.

発酵槽２５では、嫌気的条件で混合物を高温または中温でメタン発酵させる。高温メタン発酵を行う場合、発酵槽２５内の混合物の温度は３０〜６０℃程度、中温メタン発酵を行う場合は、３０〜４０℃とするとよい。発酵槽２５に導入された混合物は、乾式メタン汚泥の作用により分解されて含水率が徐々に上昇するとともに、新たな混合物の投入に伴い発酵槽２５下部に移動する。本発明では、発酵原料は発酵槽２５内に比較的長く滞留した後、発酵残渣として排泥路３５から取り出される。発酵残渣の一部は、排泥路３５に接続された汚泥返送路３６を介して返送汚泥として混合装置２３に返送される。   In the fermenter 25, the mixture is subjected to methane fermentation at high temperature or medium temperature under anaerobic conditions. When performing high temperature methane fermentation, the temperature of the mixture in the fermenter 25 is preferably about 30 to 60 ° C, and when performing medium temperature methane fermentation, the temperature is preferably 30 to 40 ° C. The mixture introduced into the fermenter 25 is decomposed by the action of dry methane sludge so that the water content gradually increases, and moves to the lower part of the fermenter 25 as a new mixture is introduced. In the present invention, the fermentation raw material stays in the fermentation tank 25 for a relatively long time, and then is taken out from the waste mud passage 35 as a fermentation residue. A part of the fermentation residue is returned to the mixing device 23 as return sludge via a sludge return path 36 connected to the sludge path 35.

発酵槽２５からの発酵残渣の一日あたりの引き抜き量は、槽内に保持される混合物の０．１〜１倍、特に０．２〜０・５倍として、引き抜いた発酵残渣の一部を循環比が１〜６回／週となるように汚泥返送路３６を介して発酵槽２５へ循環させることが好ましい。なお、返送汚泥は発酵原料と混合することなく、直接、発酵槽２５へ循環させてもよい。しかし、返送汚泥を発酵原料と発酵槽２５外で混合することにより、ＴＳ濃度が高い発酵原料中にメタン細菌を容易に分散させることができ、また発酵槽２５内のメタン発酵条件の撹乱が防止できるため、返送汚泥は混合装置２３に返送することが好ましい。   The extraction amount per day of the fermentation residue from the fermenter 25 is 0.1 to 1 times, particularly 0.2 to 0.5 times the mixture retained in the tank, and a part of the extracted fermentation residue is used. It is preferable to circulate to the fermenter 25 through the sludge return path 36 so that the circulation ratio is 1 to 6 times / week. In addition, you may circulate return sludge directly to the fermenter 25, without mixing with a fermentation raw material. However, by mixing the return sludge outside the fermentation tank 25 with the fermentation raw material, methane bacteria can be easily dispersed in the fermentation raw material having a high TS concentration, and disturbance of the methane fermentation conditions in the fermentation tank 25 is prevented. Therefore, it is preferable to return the returned sludge to the mixing device 23.

発酵槽２５から取り出された発酵残渣のうち、返送汚泥を除いた余剰分は、排泥路３５から堆肥化装置２９Ａ等に供給され、堆肥等の原料とすることができる。また、発酵槽２５内で有機性廃棄物がメタン発酵されることにより発生するメタンガスは、ガス路３７から発酵槽２５外へ取り出し、発電装置２７等のエネルギー源として利用できる。ガス路３７の途中には硫化水素等の不純物を除去する精製装置（図示せず）を設けてもよい。また、発電装置２７から排出される廃熱は、堆肥化装置２９Ａ等の熱源等として利用できる。   Of the fermentation residue taken out from the fermenter 25, the surplus except the return sludge is supplied from the mud passage 35 to the composting device 29A and the like, and can be used as a raw material such as compost. Further, methane gas generated by methane fermentation of organic waste in the fermenter 25 can be taken out from the gas passage 37 to the outside of the fermenter 25 and used as an energy source for the power generator 27 and the like. A purification device (not shown) for removing impurities such as hydrogen sulfide may be provided in the middle of the gas passage 37. Moreover, the waste heat discharged | emitted from the electric power generating apparatus 27 can be utilized as heat sources, etc. of the composting apparatus 29A.

［実施例１］
実施例１として、図１に示す処理装置１１を用い、固形状低Ｃ／Ｎ有機性廃棄物として鶏糞を処理した。鶏糞は含水率が６０質量％、有機物濃度７５質量％（乾重）、全窒素（Ｔ−Ｎ）濃度１．８質量％（湿重）、全リン（Ｔ−Ｐ）濃度１．７質量％（湿重）、マグネシウム（Ｍｇ）濃度６，５００ｍｇ／ｋｇ（湿重）、Ｃ／Ｎ比８．５であった。 [Example 1]
As Example 1, chicken manure was treated as a solid low C / N organic waste using the treatment apparatus 11 shown in FIG. Chicken manure has a moisture content of 60% by weight, organic matter concentration of 75% by weight (dry weight), total nitrogen (TN) concentration of 1.8% by weight (wet weight), and total phosphorus (TP) concentration of 1.7% by weight. (Wet weight), magnesium (Mg) concentration was 6,500 mg / kg (wet weight), and the C / N ratio was 8.5.

鶏糞は、混合装置２３を用いて返送汚泥と混合した後、分解速度が４ｋｇ―ＶＳ／ｍ３／日となるように８ｋｇ―ＶＳ／ｍ３／日の供給速度で発酵槽２５に供給した。発酵槽２５におけるメタン発酵工程の処理条件を以下に示す。なお、発酵原料と混合する乾式メタン汚泥は、鶏糞と一般ごみを用いて、３０日間かけて有機物負荷を４ｋｇ−ＶＳ／ｍ３／日から８ｋｇ−ＶＳ／ｍ３／日まで徐々に増大させることにより、ＴＳ濃度３５質量％としたものである。得られた乾式メタン汚泥を用いた場合の上記鶏糞の最大分解速度は６．５ｋｇ−ＶＳ／ｍ３／日である。 Chicken manure, after mixing with the return sludge with the mixing device 23, the degradation rate was fed into the fermentor 25 at a feed rate of 4kg-VS / m 3 / day and so as to 8kg-VS / m 3 / day. The process conditions of the methane fermentation process in the fermenter 25 are shown below. In addition, dry methane sludge mixed with fermentation raw materials should gradually increase the organic load from 4 kg-VS / m 3 / day to 8 kg-VS / m 3 / day over 30 days using chicken manure and general waste. Thus, the TS concentration is set to 35% by mass. When the obtained dry methane sludge is used, the maximum decomposition rate of the chicken manure is 6.5 kg-VS / m 3 / day.

［処理条件］
発酵槽容積 ；１，２００Ｌ
発酵槽内の乾式メタン汚泥量；１，０００ｋｇ
有機物負荷 ；８ｋｇ−ＶＳ／ｍ３／日
引き抜き汚泥量 ；２４ｋｇ／日
返送汚泥量 ；１５０ｋｇ／日 [Processing conditions]
Fermenter volume: 1,200L
Amount of dry methane sludge in the fermenter; 1,000 kg
Organic load: 8 kg-VS / m 3 / day withdrawal sludge volume: 24 kg / day return sludge volume: 150 kg / day

上記条件での処理を１００日間継続した結果、アンモニア阻害は発生しなかった。また、排泥路３５から引き抜かれた発酵残渣は、含水率が３５質量％で、ＶＦＡ濃度は１，５００ｍｇ／ｋｇ（湿重）未満、ｐＨ８〜９、アンモニウム（ＮＨ４ ＋）濃度１，０００〜２，０００ｍｇ／ｋｇ（湿重）、全窒素濃度８，０００〜１２，０００ｍｇ／ｋｇ（湿重）、およびマグネシウム濃度４，０００〜５，０００ｍｇ／ｋｇ（湿重）であった。また、発酵槽２５に投入した発酵原料からのメタンガス収率は有機物あたり０．２〜０．３５Ｌ−ＣＨ４／ｇ−ＶＳであった。 As a result of continuing the treatment under the above conditions for 100 days, ammonia inhibition did not occur. In addition, the fermentation residue drawn from the mud passage 35 has a water content of 35% by mass, a VFA concentration of less than 1,500 mg / kg (wet weight), a pH of 8-9, and an ammonium (NH 4 + ) concentration of 1,000. The total nitrogen concentration was 8,000 to 12,000 mg / kg (wet weight), and the magnesium concentration was 4,000 to 5,000 mg / kg (wet weight). Also, methane gas yield from the fermentation batch inputted to the fermenter 25 was 0.2~0.35L-CH 4 / g-VS per organic matter.

［実施例２］
実施例２として、発酵原料（鶏糞）の分解速度が４〜６ｋｇ―ＶＳ／ｍ３／日となるように発酵原料の供給速度を８〜１２ｋｇ―ＶＳ／ｍ３／日とした以外は実施例１と同様にして乾式メタン発酵を行なった。かかる処理を１００日間継続した結果、メタン発酵活性は実施例１に比してやや低下したが、メタン発酵を継続することができた。また、排泥路３５から引き抜かれた発酵残渣は、含水率が３５質量％で、ＶＦＡ濃度は１，５００〜２，５００ｍｇ／ｋｇ（湿重）、ｐＨ７〜８、アンモニウム（ＮＨ４ ＋）濃度２，０００〜２，５００ｍｇ／ｋｇ（湿重）、全窒素濃度８，０００〜１２，０００ｍｇ／ｋｇ（湿重）、およびマグネシウム濃度４，０００〜５，０００ｍｇ／ｋｇ（湿重）であった。また、発酵槽２５に投入した発酵原料からのメタンガス収率は有機物あたり０．１５〜０．２５Ｌ−ＣＨ４／ｇ−ＶＳであった。 [Example 2]
As Example 2, except that the degradation rate of the fermentation material (chicken manure) has a feed rate of fermentation material so that 4~6kg-VS / m 3 / day and 8~12kg-VS / m 3 / day Example In the same manner as in No. 1, dry methane fermentation was performed. As a result of continuing this treatment for 100 days, the methane fermentation activity was slightly reduced as compared with Example 1, but methane fermentation could be continued. In addition, the fermentation residue extracted from the mud passage 35 has a moisture content of 35% by mass, a VFA concentration of 1,500 to 2,500 mg / kg (wet weight), a pH of 7 to 8, and an ammonium (NH 4 + ) concentration. 2,000 to 2,500 mg / kg (wet weight), total nitrogen concentration 8,000 to 12,000 mg / kg (wet weight), and magnesium concentration 4,000 to 5,000 mg / kg (wet weight) . Also, methane gas yield from the fermentation batch inputted to the fermenter 25 was 0.15~0.25L-CH 4 / g-VS per organic matter.

［参考例１］
参考例１として、発酵原料と返送汚泥との混合物のｐＨが８〜９となるように発酵原料に水酸化ナトリウムを添加した以外は実施例２と同様にして乾式メタン発酵を行なった。かかる処理を６０日間継続した結果、実施例１と同様に良好な処理ができた。参考例１では、排泥路３５から引き抜かれた発酵残渣は、含水率が３５質量％で、ＶＦＡ濃度は１，５００〜２，５００ｍｇ／ｋｇ（湿重）、ｐＨ８〜９、アンモニウム（ＮＨ４ ＋）濃度１，０００〜２，０００（湿重）、全窒素濃度８，０００〜１２，０００ｍｇ／ｋｇ（湿重）、およびマグネシウム濃度４，０００〜５，０００ｍｇ／ｋｇ（湿重）であった。また、発酵槽２５に投入した発酵原料からのメタンガス収率は有機物あたり０．２〜０．３５Ｌ−ＣＨ４／ｇ−ＶＳで実施例１と同等であった。 [Reference Example 1]
As Reference Example 1, dry methane fermentation was performed in the same manner as in Example 2 except that sodium hydroxide was added to the fermentation raw material so that the pH of the mixture of the fermentation raw material and the returned sludge was 8-9. As a result of continuing this treatment for 60 days, a good treatment was achieved as in Example 1. In Reference Example 1, the fermentation residue withdrawn from the sludge channel 35 has a moisture content of 35 mass%, a VFA concentration of 1,500 to 2,500 mg / kg (wet weight), pH 8 to 9, ammonium (NH 4 + ) Concentration between 1,000 and 2,000 (wet weight), total nitrogen concentration between 8,000 and 12,000 mg / kg (wet weight), and magnesium concentration between 4,000 and 5,000 mg / kg (wet weight). It was. Also, methane gas yield from the fermentation batch inputted to the fermenter 25 was the same as Example 1 by 0.2~0.35L-CH 4 / g-VS per organic matter.

［比較例１］
比較例１として、発酵原料（鶏糞）の分解速度が最大分解速度の６．５ｋｇ―ＶＳ／ｍ３／日となるように発酵原料の供給速度を１３ｋｇ―ＶＳ／ｍ３／日とした以外は実施例１と同様にして乾式メタン発酵を行なった。かかる処理を２８日間継続した結果、実験開始後２１日後に発酵残渣中のアンモニウム（ＮＨ４ ＋）濃度が２，５００ｍｇ／Ｌ（湿重）を越え、アンモニア阻害によりメタンガスの発生が停止した。この時点で、排泥路３５から引き抜かれた発酵残渣は、含水率が４０質量％で、ＶＦＡ濃度は６，５２０ｍｇ／ｋｇ（湿重）に達し、ｐＨは７を下回り、全窒素濃度８，０００〜１２，０００ｍｇ／ｋｇ（湿重）、マグネシウム濃度４，０００〜５，０００ｍｇ／ｋｇ（湿重）であった。 [Comparative Example 1]
As Comparative Example 1, except that the fermentation raw material supply rate was set to 13 kg-VS / m 3 / day so that the decomposition rate of the fermentation raw material (chicken manure) was 6.5 kg-VS / m 3 / day, which was the maximum decomposition rate. Dry methane fermentation was carried out in the same manner as in Example 1. As a result of continuing such treatment for 28 days, the concentration of ammonium (NH 4 + ) in the fermentation residue exceeded 2,500 mg / L (wet weight) 21 days after the start of the experiment, and generation of methane gas was stopped due to ammonia inhibition. At this time, the fermentation residue extracted from the sludge channel 35 has a moisture content of 40% by mass, a VFA concentration of 6,520 mg / kg (wet weight), a pH of less than 7, and a total nitrogen concentration of 8, The magnesium concentration was 4,000 to 5,000 mg / kg (wet weight).

［実施例３］
実施例３として、図１に示す処理装置１１を用い、固形状低Ｃ／Ｎ有機性廃棄物として鶏糞に代えて生ごみを用いた実験を行なった。生ごみは含水率が７０質量％、有機物濃度８０質量％（乾重）、Ｔ−Ｎ濃度１．１質量％（湿重）、Ｔ−Ｐ濃度１００ｍｇ／ｋｇ（湿重）、Ｍｇ濃度３０ｍｇ／ｋｇ（湿重）、Ｃ／Ｎ比１１であった。 [Example 3]
As Example 3, the processing apparatus 11 shown in FIG. 1 was used, and an experiment was conducted using raw garbage instead of chicken manure as a solid low C / N organic waste. Garbage has a moisture content of 70% by weight, organic matter concentration of 80% by weight (dry weight), TN concentration of 1.1% by weight (wet weight), TP concentration of 100 mg / kg (wet weight), Mg concentration of 30 mg / kg (wet weight) and C / N ratio was 11.

生ごみは、混合装置２３を用いて返送汚泥と混合した後、分解速度が４．５ｋｇ―ＶＳ／ｍ３／日となるように６ｋｇ―ＶＳ／ｍ３／日の供給速度で発酵槽２５に供給した。発酵槽２５におけるメタン発酵工程の処理条件を以下に示す。なお、発酵原料と混合する乾式メタン汚泥は、豚糞と一般ごみ（ＴＳ濃度２０質量％）を用いて、５０日間かけて有機物負荷を２．５ｋｇ−ＶＳ／ｍ３・日から６ｋｇ−ＶＳ／ｍ３・日まで徐々に増大させることにより、ＴＳ濃度１７質量％としたものである。得られた乾式メタン汚泥を用いた場合の上記生ごみの最大分解速度は８ｋｇ−ＶＳ／ｍ３／日である。 The raw garbage is mixed with the returned sludge using the mixing device 23 and then fed into the fermenter 25 at a supply rate of 6 kg-VS / m 3 / day so that the decomposition rate becomes 4.5 kg-VS / m 3 / day. Supplied. The process conditions of the methane fermentation process in the fermenter 25 are shown below. The dry methane sludge to be mixed with the fermentation raw material uses pig manure and general waste (TS concentration 20% by mass), and the organic load is increased from 2.5 kg-VS / m 3 · day to 6 kg-VS / over 50 days. By gradually increasing to m 3 · day, the TS concentration was 17% by mass. When the obtained dry methane sludge is used, the maximum decomposition rate of the above garbage is 8 kg-VS / m 3 / day.

［処理条件］
発酵槽容積 ；１，２００Ｌ
発酵槽内の乾式メタン汚泥量；１，０００ｋｇ
有機物負荷 ；６ｋｇ−ＶＳ／ｍ３・日
引き抜き汚泥量 ；２６ｔ／日
返送汚泥量 ；３００ｋｇ／日 [Processing conditions]
Fermenter volume: 1,200L
Amount of dry methane sludge in the fermenter; 1,000 kg
Organic load; 6kg-VS / m 3 · day extracted sludge amount; 26t / day return sludge amount; 300kg / day

上記条件での処理を１００日間継続した結果、メタン発酵活性は実施例１に比してやや低下したが、アンモニア阻害は発生しなかった。排泥路３５から引き抜かれた発酵残渣は、含水率が１７質量％で、ＶＦＡ濃度は１，１５０ｍｇ／ｋｇ（湿重）、ｐＨ８〜９、アンモニウム（ＮＨ４ ＋）濃度２，０００〜２，５００ｍｇ／ｋｇ（湿重）、全窒素濃度４，０００〜６，０００ｍｇ／ｋｇ（湿重）、およびマグネシウム濃度５０〜２００ｍｇ／ｋｇ（湿重）であった。また、発酵槽２５に投入した発酵原料からのメタンガス収率は有機物あたり０．２５〜０．３５Ｌ−ＣＨ４／ｇ−ＶＳであった。 As a result of continuing the treatment under the above conditions for 100 days, the methane fermentation activity was slightly reduced as compared with Example 1, but ammonia inhibition did not occur. The fermentation residue withdrawn from the sludge passage 35 has a water content of 17% by mass, a VFA concentration of 1,150 mg / kg (wet weight), pH 8-9, and an ammonium (NH 4 + ) concentration of 2,000-2, The total nitrogen concentration was 4,000 to 6,000 mg / kg (wet weight), and the magnesium concentration was 50 to 200 mg / kg (wet weight). Also, methane gas yield from the fermentation batch inputted to the fermenter 25 was 0.25~0.35L-CH 4 / g-VS per organic matter.

［参考例２］
参考例２として、発酵原料（生ごみ）の分解速度が最大分解速度の８ｋｇ―ＶＳ／ｍ３／日となるように発酵原料の供給速度を１０ｋｇ―ＶＳ／ｍ３／日とした。また、発酵原料と返送汚泥との混合物のｐＨが８〜９となるように発酵原料に水酸化ナトリウムを添加し、さらにマグネシウム源として３０質量％の塩化マグネシウム（６水和物）水溶液を発酵原料に添加した。その他の条件は、実施例３と同様にして乾式メタン発酵を６０日間、継続したところ、アンモニア阻害は発生せず、良好な処理を行なうことができた。かかる処理により得られた発酵残渣は、含水率が１７質量％で、ＶＦＡ濃度は２，６５０ｍｇ／ｋｇ（湿重）、ｐＨは８〜９、全窒素濃度６，０００〜８，０００ｍｇ／ｋｇ（湿重）、アンモニウム（ＮＨ４ ＋）濃度１，５５０ｍｇ／ｋｇ（湿重）、およびマグネシウム濃度５，０００〜６，０００ｍｇ／ｋｇ（湿重）であった。また、発酵原料からのメタンガス収率は有機物あたり０．３〜０．４Ｌ−ＣＨ４／ｇ−ＶＳであった。 [Reference Example 2]
As Reference Example 2, the feed rate of the fermentation raw material was set to 10 kg-VS / m 3 / day so that the decomposition rate of the fermentation raw material (garbage) was 8 kg-VS / m 3 / day, which is the maximum decomposition rate. In addition, sodium hydroxide is added to the fermentation raw material so that the pH of the mixture of the fermentation raw material and the returned sludge is 8 to 9, and a 30% by mass magnesium chloride (hexahydrate) aqueous solution is used as the fermentation source. Added to. As for the other conditions, when dry methane fermentation was continued for 60 days in the same manner as in Example 3, ammonia inhibition did not occur and good treatment could be performed. The fermentation residue obtained by such treatment has a water content of 17% by mass, a VFA concentration of 2,650 mg / kg (wet weight), a pH of 8-9, and a total nitrogen concentration of 6,000-8,000 mg / kg ( Wet weight), ammonium (NH 4 + ) concentration of 1,550 mg / kg (wet weight), and magnesium concentration of 5,000 to 6,000 mg / kg (wet weight). Also, methane gas yield from the fermentation material was 0.3~0.4L-CH 4 / g-VS per organic matter.

表１に上記実験例の結果を示す。   Table 1 shows the results of the above experimental example.

Figure 2007098228
Figure 2007098228

表１に示すとおり、鶏糞を最大分解速度付近で処理した比較例１ではアンモニア阻害により、メタン発酵が停止した。また、参考例１および参考例２では、ｐＨ調整剤等を添加することにより、アンモニア阻害を防止することができた。一方、実施例１では鶏糞の供給速度を低くして最大分解速度より４割程度遅い分解速度で処理することにより、ｐＨ調整剤等を添加することなく、アンモニアによるメタン発酵活性の低下を防止できた。同様に、実施例２および実施例３でもｐＨ調整剤を添加することなく、アンモニア阻害によるメタン発酵の停止を回避できた。   As shown in Table 1, methane fermentation was stopped by ammonia inhibition in Comparative Example 1 in which chicken manure was treated near the maximum decomposition rate. In Reference Example 1 and Reference Example 2, ammonia inhibition could be prevented by adding a pH adjuster or the like. On the other hand, in Example 1, by lowering the supply rate of chicken manure and processing at a decomposition rate that is about 40% slower than the maximum decomposition rate, a decrease in methane fermentation activity due to ammonia can be prevented without adding a pH adjuster or the like. It was. Similarly, also in Example 2 and Example 3, the stop of methane fermentation due to ammonia inhibition could be avoided without adding a pH adjuster.

本発明は、有機性廃棄物を原料としてメタンガスを生成するために用いることができる。   The present invention can be used to produce methane gas using organic waste as a raw material.

本発明の一実施形態に係る有機性廃棄物の処理装置を示す模式図である。It is a schematic diagram which shows the processing apparatus of the organic waste which concerns on one Embodiment of this invention.

符号の説明Explanation of symbols

１１ 処理装置
２１ 貯留槽
２３ 混合装置
２５ 発酵槽
２７ 発電装置
２９Ａ 堆肥化装置
２９Ｂ 炭化装置 DESCRIPTION OF SYMBOLS 11 Processing apparatus 21 Storage tank 23 Mixing apparatus 25 Fermenter 27 Electric power generation apparatus 29A Composting apparatus 29B Carbonization apparatus

Claims (5)

Ｃ／Ｎ比が２０以下で全固形物濃度１５質量％以上の固形状の有機性廃棄物と、全固形物濃度１５質量％以上の乾式メタン汚泥と、を混合して発酵槽において嫌気的条件下でメタン発酵させる有機性廃棄物の処理方法であって、
前記発酵槽での前記有機性廃棄物中の有機物の分解速度が、前記乾式メタン汚泥による前記有機性廃棄物中の有機物の最大分解速度の９０％以下となるように前記有機性廃棄物を前記発酵槽に供給してメタン発酵させる乾式メタン発酵工程を有する有機性廃棄物の処理方法。 Anaerobic conditions in a fermenter by mixing solid organic waste having a C / N ratio of 20 or less and a total solid concentration of 15% by mass or more with dry methane sludge having a total solids concentration of 15% by mass or more. An organic waste treatment method for methane fermentation under
The organic waste is decomposed so that the decomposition rate of the organic matter in the organic waste in the fermenter is 90% or less of the maximum decomposition rate of the organic matter in the organic waste by the dry methane sludge. A method for treating organic waste having a dry methane fermentation process for supplying methane fermentation to a fermenter. 前記乾式メタン発酵工程において、前記発酵槽に導入された前記有機性廃棄物と前記乾式メタン汚泥との混合物のｐＨが８〜９の範囲となるように前記有機性廃棄物を前記発酵槽に供給する請求項１に記載の有機性廃棄物の処理方法。   In the dry methane fermentation process, the organic waste is supplied to the fermenter such that the pH of the mixture of the organic waste introduced into the fermenter and the dry methane sludge is in the range of 8-9. The organic waste processing method according to claim 1. 前記有機性廃棄物と前記乾式メタン汚泥との混合物のアンモニア態窒素１質量部に対して、リンが１質量部以上、マグネシウムが０．８質量部以上となるようにして前記乾式メタン発酵工程を行う請求項１または２に記載の有機性廃棄物の処理方法。   The dry methane fermentation process is performed so that phosphorus is 1 part by mass or more and magnesium is 0.8 part by mass or more with respect to 1 part by mass of ammonia nitrogen in the mixture of the organic waste and the dry methane sludge. The organic waste processing method according to claim 1 or 2 to be performed. Ｃ／Ｎ比が２０以下で全固形物濃度１５質量％以上の固形状の有機性廃棄物が導入され、全固形物濃度１５質量％以上の乾式メタン汚泥と該有機性廃棄物が混合された状態でメタン発酵が行われる発酵槽を有する有機性廃棄物の処理装置であって、
前記発酵槽は、該発酵槽での前記有機性廃棄物中の有機物の分解速度が、前記乾式メタン汚泥による前記有機性廃棄物中の有機物の最大分解速度の９０％以下となるように前記有機性廃棄物を該発酵槽に供給できる容積を有する有機性廃棄物の処理装置。 Solid organic waste having a C / N ratio of 20 or less and a total solid concentration of 15% by mass or more was introduced, and the dry waste methane sludge having a total solids concentration of 15% by mass or more and the organic waste were mixed. An organic waste processing apparatus having a fermenter in which methane fermentation is performed in a state,
The fermenter is configured so that a decomposition rate of organic matter in the organic waste in the fermenter is 90% or less of a maximum decomposition rate of organic matter in the organic waste by the dry methane sludge. An organic waste processing apparatus having a volume capable of supplying an organic waste to the fermenter. 前記発酵槽は、該発酵槽内に保持される前記乾式メタン汚泥と前記有機性廃棄物との混合物のｐＨを計測するｐＨ計を備え、
前記混合物のｐＨが８〜９となるように、前記発酵槽に対する前記有機性廃棄物の供給速度を調整する供給制御手段をさらに有する請求項４に記載の有機性廃棄物の処理装置。 The fermenter comprises a pH meter that measures the pH of the mixture of the dry methane sludge and the organic waste held in the fermentor,
The processing apparatus of the organic waste of Claim 4 which further has a supply control means which adjusts the supply speed | rate of the said organic waste with respect to the said fermenter so that pH of the said mixture may be 8-9.
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