JP2021194616A - Anaerobic wastewater treatment method - Google Patents

Anaerobic wastewater treatment method Download PDF

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JP2021194616A
JP2021194616A JP2020104541A JP2020104541A JP2021194616A JP 2021194616 A JP2021194616 A JP 2021194616A JP 2020104541 A JP2020104541 A JP 2020104541A JP 2020104541 A JP2020104541 A JP 2020104541A JP 2021194616 A JP2021194616 A JP 2021194616A
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carrier
wastewater
reaction tank
methanogen
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愛之 林
Yoshiyuki Hayashi
悠 鵜飼
Yu Ukai
資二 吉原
Sukeji Yoshihara
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Kuraray Co Ltd
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    • YGENERAL 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

To provide an anaerobic wastewater treatment method that can significantly reduce the time required for start-up operation and is capable of performing efficient treatment after the start-up of the reaction tank.SOLUTION: An anaerobic wastewater treatment method in which organic substances-containing wastewater is passed through a carrier-holding reaction tank and treated biologically by anaerobic microorganisms grown on the carrier, wherein the wastewater treatment method comprises a start-up operation that comprises at least: a first step of passing the wastewater through the reaction tank in the presence of the carrier and suspended substances that contain methane bacteria-containing aggregates at a rate of 1-900 g per L of the carrier; and a second step in which the CODcr load of the wastewater flowing into the reaction tank is increased at the time when it reaches a state where the amount, evaluated in terms of VSS, of bacteria (including methane bacteria) attached to the carrier is 0.5 g or more per 1 L of carrier and the suspended substances that contain methane bacteria-containing aggregates is less than 5 g per 1 L of carrier.SELECTED DRAWING: Figure 1

Description

本発明は嫌気性排水処理方法に関する。詳しくは、有機物を含有する排水を、担体を保持する反応槽に通水して該担体に増殖した嫌気性微生物により生物学的に処理する嫌気性排水処理方法に関する。 The present invention relates to an anaerobic wastewater treatment method. More specifically, the present invention relates to an anaerobic wastewater treatment method in which wastewater containing an organic substance is passed through a reaction vessel holding a carrier and biologically treated with anaerobic microorganisms grown on the carrier.

有機物を含有する排水(以下「有機性排水」と記載することがある。)の処理方法として、メタンガスの回収および再利用が可能な嫌気処理法は、広く産業排水の処理方法として用いられている。なかでも沈降性良好なグラニュールを形成し、有機性排水を上向流で通水し、高負荷高速処理を行うUASB(Up flow Anaerobic Sludge Blanket:上向流嫌気性スラッジブランケット)法は、特に中〜高濃度排水を処理する方法として発展してきた。また、このUASB法を発展させたものとして、高さの高い反応槽を用いてさらに高流速で通水し、高負荷で嫌気性処理を行うEGSB(Expanded GranuleSludge Blanket)法も実用化されている。 As a treatment method for wastewater containing organic matter (hereinafter sometimes referred to as "organic wastewater"), an anaerobic treatment method capable of recovering and reusing methane gas is widely used as a treatment method for industrial wastewater. .. Among them, the UASB (Upflow Anaerobic Sludge Blanket) method, which forms a granule with good sedimentation property, allows organic wastewater to flow in an upward flow, and performs high-load high-speed treatment, is particularly effective. It has been developed as a method for treating medium to high concentration wastewater. In addition, as an extension of this UASB method, the EGSB (Expanded Granule Blanket) method, in which water is passed at a higher flow rate using a high reaction tank and anaerobic treatment is performed with a high load, has also been put into practical use. ..

また、有機性排水の処理方法として、固定床担体や流動床担体を使用する方法も用いられている。固定床担体は生物膜を保持する支持床を反応槽内部に固定し、その表面に生育する微生物(以下「菌体」と記載することがある。)を利用して排水を処理するものであり、流動床担体は比重や大きさを調整した担体を反応槽内部で流動させて、担体に生物を増殖させて排水の処理を行なうものである。 Further, as a method for treating organic wastewater, a method using a fixed bed carrier or a fluidized bed carrier is also used. The fixed-bed carrier fixes a support bed that holds a biofilm inside the reaction vessel, and treats wastewater using microorganisms that grow on the surface (hereinafter sometimes referred to as "bacteria"). In the fluidized bed carrier, a carrier whose specific gravity and size have been adjusted is allowed to flow inside the reaction vessel, and organisms are propagated on the carrier to treat wastewater.

しかし、固定床担体、流動床担体を問わず、担体を用いる場合には、担体への微生物の増殖に時間がかかり、結果として反応槽の立ち上げに多大な時間を要するという大きな欠点があった。 However, when a carrier is used regardless of whether it is a fixed bed carrier or a fluidized bed carrier, there is a big drawback that it takes time for microorganisms to grow on the carrier, and as a result, it takes a lot of time to set up the reaction vessel. ..

このような課題に対し例えば特許文献1には、有機性排水の処理に関し、非生物担体とグラニュール(平均粒径0.5〜3.0mm)を存在させた状態で有機性排水の通水を開始する反応槽の立ち上げ方法が提案されている。 To address such issues, for example, Patent Document 1 describes the treatment of organic wastewater in the presence of an abiotic carrier and granules (average particle size 0.5 to 3.0 mm). A method of starting up the reaction tank has been proposed.

また、特許文献2には、反応槽の立ち上げに際して、該反応槽に担体とメタン菌凝集物とを存在させた状態で該有機性排水の通水を開始する有機性排水の処理方法であって、メタン菌凝集物の平均粒径が10μm以上450μm以下のものを使用し、担体との接触効率を上げる方法が提案されている。 Further, Patent Document 2 is a method for treating organic wastewater, which starts the passage of organic wastewater in a state where a carrier and agglomerates of methane bacteria are present in the reaction tank when the reaction tank is started up. Therefore, a method has been proposed in which the average particle size of the methanogen aggregate is 10 μm or more and 450 μm or less to improve the contact efficiency with the carrier.

特開2012−110821号公報Japanese Unexamined Patent Publication No. 2012-110821 特開2014−100680号公報Japanese Unexamined Patent Publication No. 2014-100680

しかし、特許文献1および特許文献2に記載のいずれの方法も担体への菌が付着・増殖が十分でなく、グラニュールやメタン菌凝集物が十分存在するうちは排水処理ができたとしても、担体に菌が十分付着・増殖しないうちにグラニュールやメタン菌凝集物が解体・流出し排水処理能力が低下するという問題を起こす可能性があり、十分な方法とは言い難かった。 However, in either of the methods described in Patent Document 1 and Patent Document 2, even if the bacteria adhere to and proliferate on the carrier sufficiently and the wastewater can be treated while sufficient granules and methanogen aggregates are present, the wastewater can be treated. Granules and methanogen aggregates may be disassembled and flowed out before the bacteria sufficiently adhere to and multiply on the carrier, causing a problem that the wastewater treatment capacity is reduced, and it is difficult to say that this is a sufficient method.

本発明は、有機性排水を、担体を保持する反応槽に通水して該担体に増殖した嫌気性微生物により生物学的に処理する方法において、反応槽の立ち上げ運転に要する時間を大幅に短縮すると共に、反応槽の立ち上げ後においても効率的な処理を行うことができる嫌気性排水処理方法を提供することを課題とする。なお、以下において、担体を保持する反応槽に有機性排水の通水を行って処理装置である反応槽の立ち上げを行うことを立ち上げ運転と称する。 INDUSTRIAL APPLICABILITY In the present invention, in a method in which organic wastewater is passed through a reaction vessel holding a carrier and biologically treated with anaerobic microorganisms grown on the carrier, the time required for the start-up operation of the reaction vessel is significantly increased. It is an object of the present invention to provide an anaerobic wastewater treatment method capable of shortening the time and performing efficient treatment even after the reaction tank is started up. In the following, the process of starting up the reaction tank, which is a treatment device, by passing organic wastewater through the reaction tank holding the carrier is referred to as a start-up operation.

本発明者らは、鋭意検討を重ねた結果、上記課題は、以下の発明により解決することができることを見出した。 As a result of diligent studies, the present inventors have found that the above problems can be solved by the following inventions.

本発明の一局面に係る嫌気性排水処理方法は、有機物を含有する排水を、担体を保持する反応槽に通水して、該担体に増殖した嫌気性微生物により生物学的に処理する嫌気性排水処理方法において、該反応槽内に、前記担体と、担体1Lあたり1〜900gとなるようにメタン菌凝集物を含む浮遊物質と、を存在させた状態で、前記排水を通水する第一工程と、前記担体へのメタン菌を含む菌体の付着量をVSS(Volatile Suspended Solids:揮発性浮遊物質)で評価したときのVSS量が担体1Lあたり0.5g以上であり、前記メタン菌凝集物を含む浮遊物質が担体1Lあたり5g未満となった状態から、前記反応槽に通水する前記排水のCODcr負荷を増加させる第二工程と、を少なくとも有する立上運転を行う。 The anaerobic wastewater treatment method according to one aspect of the present invention is anaerobic in which wastewater containing organic substances is passed through a reaction vessel holding a carrier and biologically treated with anaerobic microorganisms grown on the carrier. In the wastewater treatment method, the wastewater is passed through in a state where the carrier and a suspended solid containing methane bacteria aggregates so as to be 1 to 900 g per 1 L of the carrier are present in the reaction tank. When the step and the amount of adhered cells containing methane bacteria to the carrier were evaluated by VSS (Volatile Suspended Solids), the amount of VSS was 0.5 g or more per 1 L of the carrier, and the methane bacteria aggregated. From the state where the suspended solids containing substances are less than 5 g per 1 L of the carrier, a start-up operation having at least a second step of increasing the CODcr load of the wastewater passing through the reaction tank is performed.

本発明によれば、反応槽の立ち上げ運転に要する時間を大幅に短縮すると共に、反応槽の立ち上げ後においても効率的な処理を行うことができる嫌気性排水処理方法を提供することができる。 According to the present invention, it is possible to provide an anaerobic wastewater treatment method capable of significantly shortening the time required for the start-up operation of the reaction tank and performing efficient treatment even after the start-up of the reaction tank. ..

本発明を実施するための一例のフローを模式的に表した図である。It is a figure which represented the flow of an example for carrying out this invention schematically.

本発明者らは、鋭意検討を重ねた結果、有機物を含有する排水(有機性排水)を、担体を保持する反応槽に通水して、担体に増殖した嫌気性微生物により生物学的に処理する嫌気性排水処理方法において、反応槽に担体とメタン菌凝集物とを存在させた状態で有機性排水の通水を開始し、担体に一定以上の菌体を付着させた後、反応槽のメタン菌凝集物を一定量未満にし、COD(Chemical Oxygen Demand:化学的酸素要求量。特に二クロム酸カリウムを用いて測定したCODをCODcrと称す。)負荷が低い段階から主に担体に付着したメタン菌で有機物を除去して立ち上げ運転を行うことで、担体に効率よくメタン菌を付着増殖させることができることを見出した。本発明は、このような知見に基づいてなされたものであり、以下では本発明の一実施形態について説明する。 As a result of diligent studies, the present inventors pass water containing organic substances (organic wastewater) through a reaction vessel holding a carrier and biologically treat it with anaerobic microorganisms grown on the carrier. In the anaerobic wastewater treatment method, organic wastewater is started to flow in a state where the carrier and methanogen aggregates are present in the reaction tank, and after a certain amount of bacterial cells are attached to the carrier, the reaction tank is subjected to. The amount of methanogen aggregates was reduced to less than a certain amount, and COD (Chemical Oxygen Demand: chemical oxygen demand, especially COD measured using potassium dichromate is called CODcr) adhered mainly to the carrier from the stage when the load was low. It has been found that by removing organic substances with methane bacteria and performing a start-up operation, methane bacteria can be efficiently attached and propagated on the carrier. The present invention has been made based on such findings, and an embodiment of the present invention will be described below.

本実施形態に係る嫌気性排水処理方法は、有機物性排水を、担体を保持する反応槽に通水して、該担体に増殖した嫌気性微生物により生物学的に処理する嫌気性排水処理方法において、該反応槽内に、前記担体と、担体1Lあたり1〜900gとなるようにメタン菌凝集物を含む浮遊物質と、を存在させた状態で、前記排水を通水する第一工程と、前記担体へのメタン菌を含む菌体の付着量をVSSで評価したときのVSS量が担体1Lあたり0.5g以上であり、前記メタン菌凝集物を含む浮遊物質が担体1Lあたり5g未満となった状態から、前記反応槽に通水する前記排水のCODcr負荷を増加させる第二工程と、を少なくとも有する立上運転を行う方法である。 The anaerobic wastewater treatment method according to the present embodiment is an anaerobic wastewater treatment method in which organic wastewater is passed through a reaction vessel holding a carrier and biologically treated by anaerobic microorganisms grown on the carrier. The first step of passing the waste water through the carrier and a suspended substance containing methanogen aggregates so as to be 1 to 900 g per 1 L of the carrier in the reaction vessel. When the amount of bacterial cells containing methane bacteria attached to the carrier was evaluated by VSS, the amount of VSS was 0.5 g or more per 1 L of the carrier, and the suspended substance containing the agglomerates of the methane bacteria was less than 5 g per 1 L of the carrier. It is a method of performing a start-up operation having at least a second step of increasing the CODcr load of the wastewater flowing through the reaction tank from the state.

この方法によれば、メタン菌凝集物から担体へメタン菌を含む菌体が付着し、その担体に付着した菌体に有機物が行き渡り、担体における菌体増殖を促進させることができる。 According to this method, bacterial cells containing methane bacteria adhere to the carrier from the aggregates of methane bacteria, and organic substances are distributed to the bacterial cells attached to the carrier, and the growth of the bacterial cells on the carrier can be promoted.

より詳細に説明する。嫌気性排水処理を行うための反応槽では、菌体は有機性排水の有機物を分解して増殖する。しかし、反応槽の立ち上げに際して、反応槽内にメタン菌凝集物が多く存在すると、担体に付着した菌体に有機物が行き渡らず、担体において菌体増殖が促進されない。また、CODcr負荷が高い状態でメタン菌凝集物が解体・流出すると、担体に付着した菌体だけでは排水中の有機物の分解が追いつかず、菌体増殖阻害物質の存在比が高くなり、担体における菌体増殖が促進されない。 It will be explained in more detail. In the reaction tank for anaerobic wastewater treatment, bacterial cells decompose organic matter in organic wastewater and proliferate. However, if a large amount of methanogen aggregates are present in the reaction tank at the time of starting up the reaction tank, the organic matter does not spread to the cells adhering to the carrier, and the growth of the cells is not promoted on the carrier. In addition, when methane bacteria aggregates are disassembled and flowed out under a high CODcr load, the decomposition of organic matter in the wastewater cannot catch up with the cells attached to the carrier alone, and the abundance ratio of the cell growth inhibitor increases in the carrier. Cell growth is not promoted.

これらの問題に対し、本実施形態に係る嫌気性排水処理方法では、立ち上げ運転の開始時にメタン菌凝集物を使用して担体に一定量の菌体を付着させた後、メタン菌凝集物が一定量未満になってからCODcr負荷を順次上げる方法をとることとした。これにより、担体に付着した菌体に有機物が十分に行き渡ることで、担体への菌体の付着・増殖が促進され、立ち上げ運転に要する時間を大幅に短縮すると共に、反応槽の立ち上げ運転を完了した後においても効率的な処理を行うことができる。 In response to these problems, in the anaerobic wastewater treatment method according to the present embodiment, a certain amount of methanogen aggregates are attached to the carrier using methane bacteria aggregates at the start of the start-up operation, and then the methane bacteria aggregates are formed. It was decided to take a method of gradually increasing the CODcr load after the amount becomes less than a certain amount. As a result, the organic matter is sufficiently distributed to the cells adhering to the carrier, and the adhesion and proliferation of the cells to the carrier are promoted, the time required for the start-up operation is greatly shortened, and the start-up operation of the reaction tank is carried out. Efficient processing can be performed even after the completion of.

本実施形態において、処理対象とする有機性排水は、嫌気性微生物により処理可能な有機物を含むものであればよく、そのCODcr濃度、排水の種類に規定はないが、具体的には、食品工場等の製造排水、化学工場等の有機性排水、一般下水等が挙げられる。しかし、何らこれらに限定されるものではない。有機性排水の有機物濃度は特に限定されるものではなく、例えばCODcr濃度で500〜50000mg/Lとすることができ、幅広く適用できる。有機性排水の有機物濃度はCODcr濃度で、例えば500〜50000mg/Lなど幅広く適用できる。次に、各工程について説明する。 In the present embodiment, the organic wastewater to be treated may contain organic substances that can be treated by anaerobic microorganisms, and the CODcr concentration and the type of wastewater are not specified, but specifically, a food factory. Such as manufacturing wastewater, organic wastewater from chemical factories, general sewage, etc. However, it is not limited to these. The organic matter concentration of the organic wastewater is not particularly limited, and for example, the CODcr concentration can be 500 to 50,000 mg / L, and can be widely applied. The organic matter concentration of the organic wastewater is the CODcr concentration, and can be widely applied, for example, 500 to 50,000 mg / L. Next, each step will be described.

(第一工程)
担体にメタン菌を含む菌体を付着させるために、メタン菌凝集物が必要となる。そのため、第一工程で反応槽に有機性排水を通水開始する時点で、担体を保持する反応槽内において、メタン菌凝集物を、担体1Lあたり1〜900gの範囲で存在させる。通水開始時点での反応槽内におけるメタン菌凝集物の量は、担体1Lあたり100g以下が好ましく、50g以下がより好ましい。メタン菌凝集物が、担体1Lあたり1gよりも少ないと本発明の効果を十分に得ることができず、担体1Lあたり900gよりも多いと粘度が上昇し撹拌が困難となる可能性がある。また、反応槽内からのメタン菌凝集物の流出が多く、処理水の悪化が懸念されるため好ましくない。ここでいう、反応槽内におけるメタン菌凝集物の量とは、VSSの量、すなわち浮遊しているメタン菌凝集物の量のことである。VSSは、有機性固形物の総量の目安として用いられる。VSS量は以下に記載の方法で測定される。
(First step)
Methanogen aggregates are required to attach methanogen-containing cells to the carrier. Therefore, at the time when the organic wastewater is started to flow through the reaction tank in the first step, the methanogen aggregate is present in the range of 1 to 900 g per 1 L of the carrier in the reaction tank holding the carrier. The amount of methanogen aggregates in the reaction vessel at the start of water flow is preferably 100 g or less, and more preferably 50 g or less per 1 L of the carrier. If the amount of methanogen aggregates is less than 1 g per 1 L of the carrier, the effect of the present invention cannot be sufficiently obtained, and if it is more than 900 g per 1 L of the carrier, the viscosity may increase and stirring may become difficult. In addition, a large amount of methanogen aggregates flow out from the reaction vessel, which is not preferable because there is a concern that the treated water may deteriorate. The amount of methanogen aggregates in the reaction vessel referred to here is the amount of VSS, that is, the amount of floating methanogen aggregates. VSS is used as a measure of the total amount of organic solids. The VSS amount is measured by the method described below.

<反応槽内メタン菌凝集物量の測定方法>
まず、反応槽中の浮遊性物質(SS:Suspended Solids)の量をJIS K 0102:201314.1に従って測定する。ただし、孔径1μmのろ紙を通過するSSが存在する場合は、孔径0.45μmのろ紙を使用する。試料のSS量(a)を求めた後、ろ紙を600±25℃で30〜60分間十分に強熱し、残渣の重量(b)を測定する。反応槽内メタン菌凝集物量(VSS量)は式(I)で表される。
(反応槽内メタン菌凝集物量(g))=((a−b)/V)×V′・・・(I)
a:SS量(g)
b:残渣重量(g)
V:試料(L)
V′:反応槽内水量(L)
<Measurement method of the amount of methanogen aggregates in the reaction tank>
First, the amount of suspended solids (SS: Suspended Solids) in the reaction vessel is measured according to JIS K 0102: 20134.1.1. However, if there is an SS that passes through the filter paper having a hole diameter of 1 μm, the filter paper having a hole diameter of 0.45 μm is used. After determining the SS amount (a) of the sample, the filter paper is sufficiently heated at 600 ± 25 ° C. for 30 to 60 minutes, and the weight (b) of the residue is measured. The amount of methanogen aggregate (VSS amount) in the reaction vessel is represented by the formula (I).
(Amount of methane bacteria aggregate in reaction tank (g)) = ((ab) / V) × V ′ ... (I)
a: SS amount (g)
b: Residue weight (g)
V: Sample (L)
V': Amount of water in the reaction tank (L)

以上の条件で担体とメタン菌凝集物とを収容する反応槽に有機性排水の通水を開始し、メタン菌凝集物から反応槽の担体へ菌体を付着させる。この時、有機性排水のCODcr容積負荷は0.5kg/m/d以上5.0kg/m/d以下であることが好ましい。また、CODcr容積負荷は、2kg/m/d以上であることがより好ましい。CODcr容積負荷が低すぎるとメタン菌凝集物から担体へ菌体の付着に要する期間が長くなり、高すぎると担体へ菌体が付着する前にメタン菌凝集物が解体・排出される。 Under the above conditions, the organic wastewater is started to flow through the reaction tank containing the carrier and the methane bacterium aggregate, and the methane bacterium aggregate adheres to the carrier of the reaction tank. At this time, the CODcr volumetric load of the organic wastewater is preferably 0.5 kg / m 3 / d or more and 5.0 kg / m 3 / d or less. Further, the CODcr volumetric load is more preferably 2 kg / m 3 / d or more. If the CODcr volume load is too low, the period required for the cells to adhere to the carrier from the methane bacteria aggregates becomes long, and if it is too high, the methane bacteria aggregates are disassembled and discharged before the cells adhere to the carrier.

(第二工程)
第二工程では、第一工程で、担体へのメタン菌を含む菌体の付着量をVSSで評価したときのVSS量が担体1Lあたり0.5g以上であり、メタン菌凝集物を含む浮遊物質が担体1Lあたり5g未満となった状態から、反応槽に通水する有機性排水のCODcr負荷を増加させる。有機性排水のCODcr負荷は、1回だけ増加させてもよいし、連続的に増加させてもよいし、段階的に増加させてもよい。
(Second step)
In the second step, the amount of VSS when the amount of adhered cells containing methanogens to the carrier was evaluated by VSS in the first step was 0.5 g or more per 1 L of the carrier, and the suspended solids containing methanogen aggregates were present. From the state where the amount is less than 5 g per 1 L of the carrier, the CODcr load of the organic wastewater passing through the reaction tank is increased. The CODcr load of the organic wastewater may be increased only once, continuously or gradually.

第二工程へ移行する時に、担体の菌体量が少なすぎると、メタン菌凝集物が反応槽で少なくなった時、担体に付着した菌体だけでは有機性排水を十分に処理できず、阻害物質が多く残存するため、担体に付着した菌体が増え難くなる。そのため、第二工程へ移行する時点で、反応槽の担体に付着している菌体量は一定量以上必要である。 If the amount of bacterial cells on the carrier is too small when moving to the second step, when the amount of methanogen aggregates is low in the reaction tank, the bacterial cells attached to the carrier cannot sufficiently treat the organic wastewater and inhibit it. Since a large amount of the substance remains, it becomes difficult for the cells attached to the carrier to increase. Therefore, at the time of shifting to the second step, the amount of cells adhering to the carrier of the reaction tank needs to be a certain amount or more.

本実施形態では、第二工程に移行する時点での反応槽に収容された担体へのメタン菌を含む菌体の付着量は、担体1Lあたり0.5g以上とする。担体への菌体の付着量は、担体1Lあたり0.6g以上が好ましい。本実施形態では、担体への菌体の付着量は、VSSで評価する。本明細書では、VSSで評価した担体へのメタン菌を含む菌体の付着量(VSS量)を「担体のVSS量」ともいう。担体のVSS量は以下に記載の方法で測定される。 In the present embodiment, the amount of bacterial cells containing methane bacteria attached to the carrier contained in the reaction tank at the time of transition to the second step is 0.5 g or more per 1 L of the carrier. The amount of the cells attached to the carrier is preferably 0.6 g or more per 1 L of the carrier. In this embodiment, the amount of bacterial cells attached to the carrier is evaluated by VSS. In the present specification, the amount of adhered cells containing methane bacteria (VSS amount) to the carrier evaluated by VSS is also referred to as "VSS amount of carrier". The VSS amount of the carrier is measured by the method described below.

<担体のVSS量の測定方法>
まず、菌体が付着した担体と付着していない担体、それぞれを同量取り、95℃から105℃で十分乾燥させ、試料とする。それぞれの試料の重量(c、d)を測定し、下記式(II)で表される担体に付着したSS量を算出する(「菌体が付着している担体と付着していない担体、それぞれを同量取る」とは担体の個数や体積などの量を等しく取ることを意味するが、体積など菌体の増殖により見かけの値が変わるものは、それを加味して補正する必要がある。以下は個数を基準として説明する)。次にそれぞれの試料を600±25℃で30〜60分間十分に強熱し、残渣の重量(e、f)を測定する。担体のVSS量は下記式(III)で表される。
(1個当たりの担体に付着したSS量(g/個))=(c−d)/M・・・(II)
c:菌体が付着した担体の乾燥重量(g)
d:菌体が付着していない担体の乾燥重量(g)
M:試料の個数(個)
(担体のVSS量(g))=((s−(e−f)/M)/N)×N′・・・(III)
s:1個当たりの担体に付着したSS量(g/個)
e:菌体が付着した担体の残渣重量(g)
f:菌体が付着していない担体の残渣重量(g)
N:1個当たりの菌体が付着した担体体積(L/個)
N′:反応槽内の担体体積(L)
<Measuring method of VSS amount of carrier>
First, take the same amount of each of the carrier to which the bacterial cells are attached and the carrier to which the cells are not attached, and sufficiently dry the carrier at 95 ° C to 105 ° C to prepare a sample. The weight (c, d) of each sample is measured, and the amount of SS attached to the carrier represented by the following formula (II) is calculated (“carrier with bacterial cells and carrier without bacterial cells, respectively). "Take the same amount" means to take the same amount of carriers such as the number of carriers and the volume, but if the apparent value changes due to the growth of cells such as the volume, it is necessary to take it into consideration and correct it. The following will be explained based on the number of pieces). Next, each sample is sufficiently heated at 600 ± 25 ° C. for 30 to 60 minutes, and the weight of the residue (e, f) is measured. The VSS amount of the carrier is represented by the following formula (III).
(Amount of SS attached to the carrier per piece (g / piece)) = (cd) / M ... (II)
c: Dry weight (g) of the carrier to which the bacterial cells are attached.
d: Dry weight (g) of the carrier to which the cells are not attached.
M: Number of samples (pieces)
(VSS amount (g) of carrier) = ((s- (ef) / M) / N) × N'... (III)
s: Amount of SS attached to the carrier per piece (g / piece)
e: Residual weight (g) of the carrier to which the bacterial cells are attached
f: Residual weight (g) of the carrier to which the cells are not attached
N: Carrier volume (L / piece) to which bacterial cells are attached per piece
N': Carrier volume (L) in the reaction vessel

ここで、担体のVSS量が担体1Lあたり0.5g以上になったとしても、反応槽内のメタン菌凝集物が多いと、有機性排水の有機物が主にメタン菌凝集物によって分解されてしまうため、担体に付着した菌体に有機物が行き渡らない。そのため、本実施形態では、担体のVSS量が担体1Lあたり0.5g以上になるとともに、反応槽内でメタン菌凝集物を含む浮遊物質が担体1Lあたり5g未満になってから第二工程へ移行する。 Here, even if the amount of VSS of the carrier is 0.5 g or more per 1 L of the carrier, if there are many methane bacteria aggregates in the reaction tank, the organic substances in the organic wastewater are mainly decomposed by the methane bacteria aggregates. Therefore, the organic matter does not spread to the cells attached to the carrier. Therefore, in the present embodiment, the amount of VSS of the carrier becomes 0.5 g or more per 1 L of the carrier, and the suspended solids containing methanogen aggregates become less than 5 g per 1 L of the carrier in the reaction vessel before shifting to the second step. do.

担体のVSS量が担体1Lあたり0.5g以上であり、かつ反応槽内のメタン菌凝集物が担体1Lあたり5g以上の場合は、反応槽内でメタン菌凝集物を含む浮遊物質が担体1Lあたり5g未満となるまで反応槽からメタン菌凝集物を含む浮遊物質を排出させてもよい。反応槽からメタン菌凝集物を含む浮遊物質を排出する方法としては、特に限定されるものではないが、反応槽からメタン菌凝集物を含む浮遊物質と担体とを引き抜いて担体のみ反応槽に戻す方法や、反応槽にスクリーンを設置し、反応槽内の循環流量を上げることで担体とメタン菌凝集物を含む浮遊物質とを分離して、メタン菌凝集物を含む浮遊物質のみ反応槽の後段へ排出する方法が考えられる。一方、担体のVSS量が担体1Lあたり0.5g以上になった時点で、反応槽内のメタン菌凝集物を含む浮遊物質が担体1Lあたり5g未満であれば、反応槽内のメタン菌凝集物を含む浮遊物質を排出させることなく第二工程へ移行する。 When the amount of VSS of the carrier is 0.5 g or more per 1 L of the carrier and the amount of methanogen aggregates in the reaction tank is 5 g or more per 1 L of the carrier, the suspended solids containing the methanogen aggregates in the reaction tank are per 1 L of the carrier. Suspended solids containing methanogen aggregates may be discharged from the reaction vessel until the amount is less than 5 g. The method for discharging the suspended solids containing methane bacteria aggregates from the reaction tank is not particularly limited, but the suspended solids containing methane bacteria aggregates and the carrier are extracted from the reaction tank and only the carrier is returned to the reaction tank. By installing a screen in the reaction vessel and increasing the circulating flow rate in the reaction vessel, the carrier and suspended solids containing methane bacteria aggregates are separated, and only the suspended solids containing methane bacteria aggregates are in the latter stage of the reaction vessel. A method of discharging to is conceivable. On the other hand, when the amount of VSS of the carrier becomes 0.5 g or more per 1 L of the carrier, if the suspended solids containing the methanogen aggregates in the reaction tank are less than 5 g per 1 L of the carrier, the methanogen aggregates in the reaction tank Move to the second step without discharging suspended solids containing.

CODcr容積負荷を段階的に上げる指標として、反応槽で処理された有機性排水(被処理水)のCODcr除去率を用いることができる。具体的なCODcr容積負荷の上げ方の一例としては、CODcr除去率が、所定の値以上となるごとに、反応槽に通水する有機性排水のCODcr容積負荷を増加させる方法が挙げられる。この場合の所定の値としては、CODcr除去率が80%以上であることが好ましく、85%以上であることがより好ましく、90%以上であることが更に好ましい。CODcr除去率は以下に記載の式(IV)で定義される。 The CODcr removal rate of the organic wastewater (water to be treated) treated in the reaction vessel can be used as an index for gradually increasing the CODcr volumetric load. As an example of a specific method of increasing the CODcr volumetric load, there is a method of increasing the CODcr volumetric load of the organic wastewater flowing through the reaction tank every time the CODcr removal rate becomes a predetermined value or more. As a predetermined value in this case, the CODcr removal rate is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. The CODcr removal rate is defined by the formula (IV) described below.

<CODcr除去率>
CODcr除去率(%)=({被処理水CODcr}−{処理水CODcr})÷{被処理水CODcr}×100・・・(IV)
(メタン菌凝集物)
次に、本実施形態で用いられるメタン菌凝集物について説明する。
<CODcr removal rate>
CODcr removal rate (%) = ({treated water CODcr}-{treated water CODcr}) ÷ {treated water CODcr} × 100 ... (IV)
(Methanogen aggregate)
Next, the methanogen aggregate used in this embodiment will be described.

メタン菌凝集物は粒子径が小さい方が担体との接触効率がよい。そのため、メタン菌凝集物の平均粒径は10〜450μmの範囲であることが好ましく、100〜400μmの範囲であることがより好ましい。 The smaller the particle size of the methanogen aggregate, the better the contact efficiency with the carrier. Therefore, the average particle size of the methanogen aggregate is preferably in the range of 10 to 450 μm, more preferably in the range of 100 to 400 μm.

反応槽のメタン菌凝集物は、酸生成菌とメタン生成菌が含まれているものであればよいが、UASB法やEGSB法で使用されているメタン菌グラニュール(平均粒径0.5〜3.0mm)は嫌気処理を行っているため、酸生成菌とメタン生成菌を多く含んでおり、高い活性を持つ。そのため、メタン菌凝集物はメタン菌グラニュールが好ましい。メタン菌グラニュールを使用する場合は、そのまま使用してもよいが、平均粒径が10μm以上450μm以下のメタン菌グラニュールの破砕物を使用するのが好ましい。破砕物の平均粒径の下限は100μm以上がより好ましく、上限は400μm以下がより好ましい。メタン菌グラニュールを破砕、粉砕させる方法は特に限定されるものではないが、ボールミル等で粉砕させる方法、ポンプを通過させて粉砕させる方法、攪拌により粉砕させる方法が挙げられる。 The methanogen aggregate in the reaction tank may contain acid-producing bacteria and methane-producing bacteria, but the methanogen granule (average particle size 0.5 to 0.5) used in the UASB method and the EGSB method. Since 3.0 mm) is anaerobically treated, it contains a large amount of acid-producing bacteria and methane-producing bacteria, and has high activity. Therefore, the methanogen aggregate is preferably a methanogen granule. When the methanogen granule is used, it may be used as it is, but it is preferable to use a crushed product of the methanogen granule having an average particle size of 10 μm or more and 450 μm or less. The lower limit of the average particle size of the crushed material is more preferably 100 μm or more, and the upper limit is more preferably 400 μm or less. The method for crushing and crushing the methanogen granule is not particularly limited, and examples thereof include a method of crushing with a ball mill or the like, a method of passing through a pump to crush, and a method of crushing by stirring.

(担体)
反応槽に用いられる担体とは、微生物(メタン菌等の菌体を含む)が付着する固体であり、公知の各種の微生物固定化担体を使用することができるが、ゲル状担体、プラスチック担体および繊維状担体からなる群より選ばれた少なくとも1種の微生物固定化担体を使用することが好ましい。その素材としては、ポリビニルアルコールといったビニルアルコール系樹脂;ポリエチレングリコールといったエーテル系樹脂;ポリメタクリル酸といったアクリル系樹脂;ポリアクリルアミドといったアクリルアミド系樹脂;ポリエチレン、ポリプロピレンといったオレフィン系樹脂、ポリスチレンといったスチレン系樹脂;ポリエチレンテレフタレートやポリブチレンテレフタレートといったエステル系樹脂;ポリアクリロニトリルといったアクリロニトリル系樹脂;ポリウレタンスポンジといったウレタン系樹脂;アルギン酸カルシウム、κ(カッパ)カラギーナン、寒天、セルロース誘導体といった多糖類;ポリエステルエアクリレート、エポキシアクリレート、ウレタンアクリレートといった光硬化性樹脂;活性炭といった多孔質無機化合物などを例示することができる。中でも、微生物の固定化に優れる観点から、ゲル状担体が好ましく、内部に至るまで多孔質で網目状となった構造を有する点、及びゲル内に多量の水を取り込むことができる点で、ポリビニルアルコール系樹脂を素材としたポリビニルアルコール系含水ゲル担体が好ましく、ホルマール化ポリビニルアルコール系含水ゲルやアセタール化ポリビニルアルコール系含水ゲルなどのポリビニルアルコール架橋ゲル担体であることがより好ましい。微生物固定化担体は、1種類でも、組み合わせても使用することができる。その充填率としては、排水処理効率と担体流動性の観点から、槽容積の5%以上50%以下であることが好ましく、10%以上40%以下であることがより好ましい。
(Carrier)
The carrier used in the reaction tank is a solid to which microorganisms (including bacterial cells such as methanogens) adhere, and various known microbial-immobilized carriers can be used, but gel-like carriers, plastic carriers and It is preferable to use at least one microbially immobilized carrier selected from the group consisting of fibrous carriers. The materials include vinyl alcohol resins such as polyvinyl alcohol; ether resins such as polyethylene glycol; acrylic resins such as polymethacrylic acid; acrylamide resins such as polyacrylamide; olefin resins such as polyethylene and polypropylene, and styrene resins such as polystyrene; polyethylene. Ester resins such as terephthalate and polybutylene terephthalate; Acrylonitrile resins such as polyacrylonitrile; Urethane resins such as polyurethane sponge; Polysaccharides such as calcium alginate, κ (kappa) carrageenan, agar and cellulose derivatives; polyester acrylate, epoxy acrylate, urethane acrylate Such as a photocurable resin; a porous inorganic compound such as activated carbon can be exemplified. Among them, a gel-like carrier is preferable from the viewpoint of excellent immobilization of microorganisms, and polyvinyl has a porous and reticulated structure up to the inside and can take a large amount of water into the gel. A polyvinyl alcohol-based hydrogel carrier made of an alcohol-based resin is preferable, and a polyvinyl alcohol cross-linked gel carrier such as a formalized polyvinyl alcohol-based hydrogel or an acetalized polyvinyl alcohol-based hydrogel is more preferable. The microorganism-immobilized carrier can be used alone or in combination. The filling rate is preferably 5% or more and 50% or less, and more preferably 10% or more and 40% or less of the tank volume from the viewpoint of wastewater treatment efficiency and carrier fluidity.

担体の球相当径は、1〜10mmであることが好ましい。球相当径が小さい場合、曝気槽に担体の流出を防ぐためのスクリーンを設置した場合に、スクリーンの網目を小さくする必要があり、目詰まりを起こすおそれがある。そのため、球相当径は2mm以上であることがより好ましい。一方、球相当径が10mmを超える場合、担体の流動性が低下するおそれがある。そのため、球相当径は6mm以下であることがより好ましい。ここで球相当径とは粒子の体積と等しい体積を有する球の直径である。 The equivalent sphere diameter of the carrier is preferably 1 to 10 mm. When the equivalent diameter of the sphere is small, when a screen for preventing the outflow of the carrier is installed in the aeration tank, it is necessary to reduce the mesh size of the screen, which may cause clogging. Therefore, it is more preferable that the equivalent diameter of the sphere is 2 mm or more. On the other hand, if the equivalent diameter of the sphere exceeds 10 mm, the fluidity of the carrier may decrease. Therefore, it is more preferable that the equivalent diameter of the sphere is 6 mm or less. Here, the sphere equivalent diameter is the diameter of a sphere having a volume equal to the volume of the particles.

担体の比重は水よりわずかに大きく、曝気槽から流失しない程度に、当該曝気槽の中で揺動させることができる比重であることが好ましい。本発明の処理方法において、比重が水よりわずかに大きい担体を用いることにより、担体を流失させることなく、より安定的に排水を処理することができるため、担体の比重は1.001以上であることが好ましく、1.005以上であることがより好ましい。一方、比重は1.2以下であることが好ましく、1.1以下であることがより好ましく、1.05以下であることがさらに好ましい。 The specific gravity of the carrier is slightly larger than that of water, and it is preferable that the carrier has a specific density that can be shaken in the aeration tank so as not to be washed away from the aeration tank. In the treatment method of the present invention, by using a carrier having a specific gravity slightly higher than that of water, wastewater can be treated more stably without causing the carrier to be washed away, so that the specific gravity of the carrier is 1.001 or more. It is preferably 1.005 or more, and more preferably 1.005 or more. On the other hand, the specific gravity is preferably 1.2 or less, more preferably 1.1 or less, and even more preferably 1.05 or less.

担体は、連通孔を有することが好ましく、該連通孔の孔径は、細菌のみが担体内部に棲息できる孔径であることが好ましい。担体表面付近の孔径が0.1〜100μmであることが好ましい。孔径が0.1μm未満の場合、細菌が担体内部に侵入できないことがある。表面付近の孔径は0.5μm以上であることがより好ましい。一方、表面付近の孔径が100μmを超える場合、細菌以外の大きな生物が浸入する恐れがある。孔径は50μm以下であることがより好ましい。なお、連通孔の孔径は、電子顕微鏡を用いた観察などの方法により測定することができる。 The carrier preferably has a communication hole, and the pore size of the communication hole is preferably a pore size in which only bacteria can live inside the carrier. The pore diameter near the surface of the carrier is preferably 0.1 to 100 μm. If the pore size is less than 0.1 μm, bacteria may not be able to invade the inside of the carrier. It is more preferable that the pore diameter near the surface is 0.5 μm or more. On the other hand, if the pore size near the surface exceeds 100 μm, large organisms other than bacteria may invade. The pore diameter is more preferably 50 μm or less. The pore diameter of the communication hole can be measured by a method such as observation using an electron microscope.

担体は、沈降速度として100〜500m/hrのものが好ましい。担体の沈降速度が小さいと、水流、発生ガスにより浮上し易く、水面近くにスカム状に蓄積してしまう。非生物担体では、菌体の付着で表面に生物膜が形成され、生物膜内部でガスが発生する反応が進行するため、担体の見掛け比重は生物膜の形成に伴って軽くなっていく。この生物膜の影響を考慮して、担体自体の比重、沈降速度を決定する必要がある。逆に沈降速度が大きすぎると有機性排水との接触効率が悪くなり、十分な処理性能を得ることができない場合があり、また担体の堆積層に固形物が蓄積して有機性排水流路が閉塞するといった弊害が出る可能性がある。 The carrier preferably has a settling speed of 100 to 500 m / hr. If the sedimentation speed of the carrier is low, it tends to float due to water flow and generated gas, and accumulates in a scum shape near the water surface. In the abiotic carrier, a biofilm is formed on the surface due to the adhesion of the bacterial cells, and the reaction of generating gas inside the biofilm proceeds, so that the apparent specific gravity of the carrier becomes lighter with the formation of the biofilm. It is necessary to determine the specific gravity and sedimentation rate of the carrier itself in consideration of the influence of this biofilm. On the other hand, if the sedimentation rate is too high, the contact efficiency with the organic wastewater will deteriorate, and sufficient treatment performance may not be obtained. In addition, solid matter will accumulate in the sedimentary layer of the carrier and the organic wastewater flow path will be created. There is a possibility that it will be blocked.

(嫌気性排水処理方法における処理条件)
本実施形態に係る嫌気性排水処理方法を含む排水処理フローの一例を図1に示す。図1を用いて本実施形態に係る排水処理方法について、上記の処理条件以外の処理条件を含めて説明する。図1に示す排水処理フローでは、有機性排水1の原水を収容し、処理する酸生成槽2と、酸生成槽2で処理された有機性排水1をさらに処理する反応槽3と、反応槽3で処理された有機性排水1を収容するとともに処理水6を排出する処理水受け槽4と、処理水受け槽4から排出された処理水の一部を酸生成槽2に戻す処理水返送管5と、を備えるシステムを用いる。立上時の反応槽3には、上述の担体とメタン菌凝集物とが収容されており、上述の第一工程および第二工程は反応槽3で行われる。
(Treatment conditions in the anaerobic wastewater treatment method)
FIG. 1 shows an example of a wastewater treatment flow including an anaerobic wastewater treatment method according to the present embodiment. The wastewater treatment method according to the present embodiment will be described with reference to FIG. 1, including treatment conditions other than the above treatment conditions. In the wastewater treatment flow shown in FIG. 1, an acid generation tank 2 that accommodates and treats the raw water of the organic wastewater 1, a reaction tank 3 that further treats the organic wastewater 1 treated by the acid generation tank 2, and a reaction tank. A treated water receiving tank 4 that accommodates the organic wastewater 1 treated in 3 and discharges the treated water 6, and a treated water return that returns a part of the treated water discharged from the treated water receiving tank 4 to the acid generation tank 2. A system comprising a tube 5 is used. The above-mentioned carrier and methane bacterium aggregates are contained in the reaction tank 3 at the time of startup, and the above-mentioned first step and second step are performed in the reaction tank 3.

本実施形態では、反応槽3における有機性排水1の処理方法には特に制限はないが、UASB法、EGSB法と同様に反応槽に有機性排水を上向流で通水する上向流型反応槽を用いる方法や撹拌機等で槽内を撹拌して流動させる完全混合型反応槽を用いる方法、窒素・メタンガス等酸素を含有しない気体で槽内を曝気流動させる方法などが挙げられる。 In the present embodiment, the method for treating the organic wastewater 1 in the reaction tank 3 is not particularly limited, but an upward flow type in which the organic wastewater is passed through the reaction tank by an upward flow as in the UASB method and the EGSB method. Examples thereof include a method using a reaction tank, a method using a completely mixed reaction tank in which the inside of the tank is stirred and flowed with a stirrer or the like, and a method in which the inside of the tank is aerated and flowed with a gas containing no oxygen such as nitrogen and methane gas.

反応槽3における有機性排水1の処理条件は、有機性排水1の生分解性等の条件によっても異なるが、pHの下限は6以上が好ましく、6.5以上がより好ましい。pHの上限は、8以下が好ましく、7.5以下がより好ましい。温度の下限は、20℃以上が好ましく、25℃以上がより好ましい。温度の上限は、40℃以下が好ましく、37℃以下がより好ましい。HRT(Hydraulic Retention Time:水理学的滞留時間)の下限は、1時間以上が好ましい。HRTの上限は、24時間以下が好ましく、8時間以下がより好ましい。LV(Linear Velocity:線速度)の下限は1m/hr以上が好ましい。LVの上限は20m/hr以下が好ましい。HRTとは、有機性排水1が酸生成槽2または反応槽3に流入してから流出するまでの平均的な時間のことである。 The treatment conditions for the organic waste water 1 in the reaction tank 3 differ depending on the conditions such as the biodegradability of the organic waste water 1, but the lower limit of the pH is preferably 6 or more, more preferably 6.5 or more. The upper limit of pH is preferably 8 or less, more preferably 7.5 or less. The lower limit of the temperature is preferably 20 ° C. or higher, more preferably 25 ° C. or higher. The upper limit of the temperature is preferably 40 ° C. or lower, more preferably 37 ° C. or lower. The lower limit of HRT (Hydraulic Retention Time) is preferably 1 hour or more. The upper limit of HRT is preferably 24 hours or less, more preferably 8 hours or less. The lower limit of LV (Linear Velocity) is preferably 1 m / hr or more. The upper limit of LV is preferably 20 m / hr or less. The HRT is an average time from when the organic waste water 1 flows into the acid generation tank 2 or the reaction tank 3 to when it flows out.

反応槽3の前段に設けられた酸生成槽2は、有機性排水1中に含まれるタンパク質等の高分子成分を酢酸等の低分子有機酸まで分解するためのものである。有機性排水1中にタンパク質等の高分子成分が殆ど含まれておらず、有機性排水1が、メタノール、酢酸等のメタン生成菌が直接利用可能な化合物のみを含む場合には、反応槽3の前段に酸生成槽2を設ける必要はない。 The acid generation tank 2 provided in front of the reaction tank 3 is for decomposing high molecular weight components such as proteins contained in the organic wastewater 1 into small molecule organic acids such as acetic acid. When the organic wastewater 1 contains almost no high molecular weight components such as proteins and the organic wastewater 1 contains only compounds that can be directly used by methane-producing bacteria such as methanol and acetic acid, the reaction tank 3 It is not necessary to provide the acid generation tank 2 in front of the above stage.

酸生成槽2の処理条件は、有機性排水の条件によっても異なるが、pHの下限は、5以上が好ましく、5.5以上がより好ましい。pHの上限は、8以下が好ましく、7.8以下がより好ましい。温度の下限は、20℃以上が好ましく、25℃以上がより好ましい。温度の上限は、40℃以下が好ましく、37℃以下がより好ましい。HRTの下限は、2時間以上が好ましい。HRTの上限は、24時間以下が好ましく、8時間以下がより好ましい。 The treatment conditions of the acid generation tank 2 differ depending on the conditions of the organic wastewater, but the lower limit of the pH is preferably 5 or more, more preferably 5.5 or more. The upper limit of pH is preferably 8 or less, more preferably 7.8 or less. The lower limit of the temperature is preferably 20 ° C. or higher, more preferably 25 ° C. or higher. The upper limit of the temperature is preferably 40 ° C. or lower, more preferably 37 ° C. or lower. The lower limit of HRT is preferably 2 hours or more. The upper limit of HRT is preferably 24 hours or less, more preferably 8 hours or less.

このシステムにおいて、立ち上げ運転を完了した後、定常運転時の反応槽3におけるCODcr容積負荷は1〜50kg/m/dであることが好ましく、5〜30kg/m/dであることがより好ましい。CODcr容積負荷が高いほど、反応槽3を小型化することができる。CODcr容積負荷とは流入する有機性排水のCODcr濃度に1日あたりの流量を積算し、反応槽容積で除算したものである。 In this system, after completing the start-up operation, it is preferable that CODcr volume loading is 1 to 50 kg / m 3 / d in the reaction vessel 3 during steady operation, to be 5~30kg / m 3 / d More preferred. The higher the CODcr volumetric load, the smaller the size of the reaction vessel 3. The CODcr volume load is obtained by adding the daily flow rate to the CODcr concentration of the inflowing organic wastewater and dividing by the reaction tank volume.

本明細書は、上述したように様々な態様の技術を開示しているが、そのうち主な技術を以下にまとめる。 As described above, the present specification discloses various aspects of the technology, of which the main technologies are summarized below.

上述したように、本発明の一局面に係る嫌気性排水処理方法は、有機物を含有する排水を、担体を保持する反応槽に通水して、該担体に増殖した嫌気性微生物により生物学的に処理する嫌気性排水処理方法において、該反応槽内に、前記担体と、担体1Lあたり1〜900gとなるようにメタン菌凝集物を含む浮遊物質と、を存在させた状態で、前記排水を通水する第一工程と、VSS量として評価した前記担体へのメタン菌を含む菌体の付着量が担体1Lあたり0.5g以上であり、前記メタン菌凝集物を含む浮遊物質が担体1Lあたり5g未満となった状態から、前記反応槽に通水する前記排水のCODcr負荷を増加させる第二工程と、を少なくとも有する立上運転を行う。 As described above, in the anaerobic wastewater treatment method according to one aspect of the present invention, wastewater containing organic substances is passed through a reaction vessel holding a carrier and biologically produced by anaerobic microorganisms grown on the carrier. In the anaerobic wastewater treatment method for treating water, the wastewater is discharged in a state where the carrier and a suspended solid containing methane bacteria aggregates so as to be 1 to 900 g per 1 L of the carrier are present in the reaction tank. In the first step of passing water, the amount of adhered cells containing methane bacteria to the carrier evaluated as the amount of VSS is 0.5 g or more per 1 L of the carrier, and the suspended solids containing the aggregates of the methane bacteria are per 1 L of the carrier. From a state of less than 5 g, a start-up operation having at least a second step of increasing the CODcr load of the wastewater passing through the reaction tank is performed.

この構成によれば、反応槽の立ち上げ運転に要する時間を大幅に短縮することができる。 According to this configuration, the time required for the start-up operation of the reaction tank can be significantly shortened.

上記構成の前記第一工程において、前記排水のCODcr容積負荷が0.5kg/m/d以上5.0kg/m/d以下であることが好ましい。 In the first step of the above configuration, it is preferable that the CODcr volumetric load of the wastewater is 0.5 kg / m 3 / d or more and 5.0 kg / m 3 / d or less.

これにより、効率よくメタン菌凝集物から担体へ菌体を付着させることができる。 This makes it possible to efficiently attach the bacterial cells from the methane bacterial aggregates to the carrier.

上記構成において、前記メタン菌凝集物の平均粒径が10μm以上450μm以下であることが好ましい。 In the above configuration, the average particle size of the methanogen aggregate is preferably 10 μm or more and 450 μm or less.

これにより、効率よくメタン菌凝集物から担体へ菌体を付着させることができる。 This makes it possible to efficiently attach the bacterial cells from the methane bacterial aggregates to the carrier.

上記構成において、前記メタン菌凝集物がメタン菌グラニュールまたはメタン菌グラニュールの破砕物であることが好ましい。 In the above configuration, it is preferable that the methanogen aggregate is a methanogen granule or a crushed product of the methanogen granule.

メタン菌グラニュールは高い活性を持つため、効率よく有機性排水を処理することができる。 Since methanogen granules have high activity, organic wastewater can be treated efficiently.

(実施例1)
図1に示すフローに従って、化学会社の実排水(有機性排水)に対する嫌気性排水処理を実施した。反応槽の仕様並びに初期処理条件は下記の通りとした。
(Example 1)
According to the flow shown in FIG. 1, anaerobic wastewater treatment was carried out for actual wastewater (organic wastewater) of a chemical company. The specifications of the reaction tank and the initial treatment conditions are as follows.

・酸生成槽の仕様
酸生成槽容量4L、槽内温度:35〜37℃、pH:7.5〜7.7
・反応槽の仕様
反応槽容量5L、槽内温度:35〜37℃、pH:6.8〜7.2
・処理水受け槽の仕様
処理水受け槽容量1L、槽内攪拌無し
・初期処理条件
原水CODcr濃度:3000mg/L
初期流量3.1L/d
初期メタン菌凝集物(平均粒径300μm)量:20g
LV:1.7m/hr
・ Specifications of acid generation tank Acid generation tank capacity 4L, tank temperature: 35-37 ° C, pH: 7.5-7.7
-Reaction tank specifications Reaction tank capacity 5 L, tank temperature: 35-37 ° C, pH: 6.8-7.2
・ Specifications of treated water receiving tank Capacity of treated water receiving tank 1L, no agitation in the tank ・ Initial treatment conditions Raw water CODcr concentration: 3000mg / L
Initial flow rate 3.1 L / d
Amount of initial methanogen aggregate (average particle size 300 μm): 20 g
LV: 1.7m / hr

反応槽にはアセタール化ポリビニルアルコール系ゲル状担体(平均粒径4mm、比重1.025、表面付近の孔径0.5〜20μm)を槽容量に対して40容量%充填した。上記初期処理条件のとおり排水の通水を開始した(第一工程開始)。立ち上げ運転の間、反応槽から排出されたメタン菌凝集物を含む浮遊物質は処理水受け槽に溜まり、その浮遊物質を槽外に排除した。通水を開始した時点での、担体のVSS量は担体1Lあたり0gであり、反応槽内のメタン菌凝集物を含む浮遊物質は担体1Lあたり10gであった。 The reaction vessel was filled with an acetalized polyvinyl alcohol-based gel-like carrier (average particle size 4 mm, specific density 1.025, pore diameter near the surface 0.5 to 20 μm) in an amount of 40% by volume based on the tank volume. The flow of wastewater was started according to the above initial treatment conditions (start of the first process). During the start-up operation, suspended solids containing methanogen aggregates discharged from the reaction tank accumulated in the treated water receiving tank, and the suspended solids were removed from the tank. At the time when water flow was started, the amount of VSS of the carrier was 0 g per 1 L of the carrier, and the suspended solid containing the methanogen aggregate in the reaction tank was 10 g per 1 L of the carrier.

排水通水の開始後3日間で担体のVSS量が担体1Lあたり0.6g、反応槽内のメタン菌凝集物を含む浮遊物質が担体1Lあたり3.2gになったのを確認した。これらの数値の確認後、排水の流量を段階的に上げることで排水CODcr負荷を上げた(第二工程開始)。排水の流量は、CODcr除去率が90%以上となったときに上げた。 It was confirmed that the amount of VSS of the carrier was 0.6 g per 1 L of the carrier and the suspended solid containing the methanogen aggregate in the reaction tank was 3.2 g per 1 L of the carrier within 3 days after the start of drainage water flow. After confirming these values, the wastewater CODcr load was increased by gradually increasing the flow rate of the wastewater (start of the second step). The flow rate of wastewater was increased when the CODcr removal rate was 90% or more.

第二工程の開始後40日間で、CODcr容積負荷13kg/m/dまで上げることができた(第二工程完了、立ち上げ運転完了)。このように、実施例1では、立ち上げ運転を43日で完了することができた。また、立ち上げ運転の間、CODcr除去率は常に90%以上を推移し、非常に良好であった。続いて排水のCODcr容積負荷を13kg/m/dで一定として定常運転を行ったところ、第二工程が完了してから2ヶ月経過後も問題なく排水処理することができた。 Within 40 days after the start of the second process, the CODcr volumetric load could be increased to 13 kg / m 3 / d (second process completed, start-up operation completed). As described above, in Example 1, the start-up operation could be completed in 43 days. In addition, during the start-up operation, the CODcr removal rate always remained at 90% or more, which was very good. Subsequently, when steady operation was performed with the CODcr volumetric load of the wastewater kept constant at 13 kg / m 3 / d, the wastewater could be treated without any problem even two months after the completion of the second step.

(比較例1)
比較例1では、反応槽の仕様並びに初期処理条件は下記の通りとした。比較例1は、LVを小さくした点で実施例1と異なる。
(Comparative Example 1)
In Comparative Example 1, the specifications of the reaction vessel and the initial treatment conditions were as follows. Comparative Example 1 is different from Example 1 in that the LV is reduced.

・酸生成槽の仕様
酸生成槽容量4L、槽内温度:35〜37℃、pH:7.5〜7.7
・反応槽の仕様
反応槽容量5L、槽内温度:35〜37℃、pH:6.8〜7.2
・処理水受け槽の仕様
処理水受け槽1L、槽内攪拌無し
・初期処理条件
原水CODcr濃度:3000mg/L
初期流量3.1L/d
初期メタン菌凝集物(平均粒径300μm)量:20g
LV:0.5m/hr
・ Specifications of acid generation tank Acid generation tank capacity 4L, tank temperature: 35-37 ° C, pH: 7.5-7.7
-Reaction tank specifications Reaction tank capacity 5 L, tank temperature: 35-37 ° C, pH: 6.8-7.2
・ Specifications of treated water receiving tank 1L of treated water receiving tank, no agitation in the tank ・ Initial treatment conditions Raw water CODcr concentration: 3000mg / L
Initial flow rate 3.1 L / d
Amount of initial methanogen aggregate (average particle size 300 μm): 20 g
LV: 0.5m / hr

反応槽には実施例1と同様の担体を槽容量に対して40容量%充填し、上記初期処理条件のとおり排水の通水を開始した。その後、排水の流量とLVを段階的に上げることで排水CODcr負荷を上げた。立ち上げ運転の間、大部分の浮遊物質は反応槽内に留まっており、反応槽から排出された浮遊物質は処理水受け槽にはほとんど見られなかった。通水を開始した時点での、担体のVSS量は担体1Lあたり0gであり、反応槽内のメタン菌凝集物を含む浮遊物質は担体1Lあたり10gであった。また、排水の流量とLVを最初に上げた時点での、担体のVSS量は担体1Lあたり1.3gであり、反応槽内のメタン菌凝集物を含む浮遊物質は担体1Lあたり7.5gであった。 The reaction tank was filled with the same carrier as in Example 1 in an amount of 40% by volume based on the tank capacity, and drainage was started to flow according to the above initial treatment conditions. After that, the drainage CODcr load was increased by gradually increasing the flow rate and LV of the drainage. During the start-up operation, most of the suspended solids remained in the reaction tank, and the suspended solids discharged from the reaction tank were hardly found in the treated water receiving tank. At the time when water flow was started, the amount of VSS of the carrier was 0 g per 1 L of the carrier, and the suspended solid containing the methanogen aggregate in the reaction tank was 10 g per 1 L of the carrier. Further, the amount of VSS of the carrier at the time when the flow rate of waste water and the LV were first increased was 1.3 g per 1 L of the carrier, and the suspended solids containing methane bacteria aggregates in the reaction tank was 7.5 g per 1 L of the carrier. there were.

通水開始後20日間で流量とLVを上げ、CODcr容積負荷を7kg/m/dまで上げた。CODcr容積負荷を7kg/m/dとしてから少しずつCODcr除去率が低下していき、通水開始後26日目に80%を下回った。この時、担体VSSは担体1Lあたり1.8gであり、反応槽内のメタン菌凝集物を含む浮遊物質は担体1Lあたり6.3gであった。 The flow rate and LV were increased 20 days after the start of water flow, and the CODcr volumetric load was increased to 7 kg / m 3 / d. After setting the CODcr volumetric load to 7 kg / m 3 / d, the CODcr removal rate gradually decreased and fell below 80% on the 26th day after the start of water flow. At this time, the carrier VSS was 1.8 g per 1 L of the carrier, and the suspended solid containing the methanogen aggregate in the reaction tank was 6.3 g per 1 L of the carrier.

通水開始後26日目にCODcr容積負荷を5kg/m/dに下げ、LVを1.7m/hrに上げた。CODcr容積負荷およびLVを変更してから10日間で反応槽内のメタン菌凝集物を含む浮遊物質が担体1Lあたり4gになったため、排水の流量を段階的に上げることで排水CODcr負荷を上げた。 On the 26th day after the start of water flow, the CODcr volumetric load was reduced to 5 kg / m 3 / d and the LV was raised to 1.7 m / hr. Since the suspended solids containing methane bacteria aggregates in the reaction vessel became 4 g per 1 L of the carrier within 10 days after changing the CODcr volume load and LV, the wastewater CODcr load was increased by gradually increasing the flow rate of the wastewater. ..

その後、排水CODcr負荷を上げ始めてから30日間でCODcr容積負荷13kg/m/日まで上げることができた(立ち上げ運転完了)。このように、比較例1では、立ち上げ運転を66日で完了することができた。また、立ち上げ運転の間、CODcr除去率は常に90%以上を推移し、非常に良好な処理性のまま2ヶ月経過後も問題なく排水処理することができた。 After that, the CODcr volumetric load could be increased to 13 kg / m 3 / day within 30 days after the drainage CODcr load was started (start-up operation completed). As described above, in Comparative Example 1, the start-up operation could be completed in 66 days. In addition, during the start-up operation, the CODcr removal rate always remained at 90% or more, and wastewater could be treated without any problem even after 2 months with very good treatability.

以上のことから、実施例1および比較例1のいずれも反応槽の立ち上げ後において効率的な処理を行うことができたことがわかる。また、実施例1では、比較例1に比べて反応槽の立ち上げ運転に要する時間を大幅に短縮することができた。 From the above, it can be seen that both Example 1 and Comparative Example 1 were able to perform efficient treatment after the reaction tank was started up. Further, in Example 1, the time required for the start-up operation of the reaction tank could be significantly shortened as compared with Comparative Example 1.

1 有機性排水
2 酸生成槽
3 反応槽
4 処理水受け槽
5 処理水返送管
6 処理水排出
1 Organic wastewater 2 Acid generation tank 3 Reaction tank 4 Treated water receiving tank 5 Treated water return pipe 6 Treated water discharge

Claims (5)

有機物を含有する排水を、担体を保持する反応槽に通水して、該担体に増殖した嫌気性微生物により生物学的に処理する嫌気性排水処理方法において、
該反応槽内に、前記担体と、担体1Lあたり1〜900gとなるようにメタン菌凝集物を含む浮遊物質と、を存在させた状態で、前記排水を通水する第一工程と、
前記担体へのメタン菌を含む菌体の付着量をVSSで評価したときのVSS量が担体1Lあたり0.5g以上であり、前記メタン菌凝集物を含む浮遊物質が担体1Lあたり5g未満となった状態から、前記反応槽に通水する前記排水のCODcr負荷を増加させる第二工程と、
を少なくとも有する立上運転を行う嫌気性排水処理方法。
In an anaerobic wastewater treatment method in which wastewater containing an organic substance is passed through a reaction vessel holding a carrier and biologically treated with anaerobic microorganisms grown on the carrier.
The first step of passing the wastewater through the reaction tank in a state where the carrier and a suspended solid containing methane bacteria aggregates so as to be 1 to 900 g per 1 L of the carrier are present.
When the amount of adhered cells containing methane bacteria to the carrier was evaluated by VSS, the amount of VSS was 0.5 g or more per 1 L of the carrier, and the suspended solids containing the agglomerates of the methane bacteria were less than 5 g per 1 L of the carrier. The second step of increasing the CODcr load of the wastewater passing through the reaction tank from the state of being
An anaerobic wastewater treatment method that has at least a start-up operation.
前記第一工程において、前記排水のCODcr容積負荷が0.5kg/m/d以上5.0kg/m/d以下である、請求項1に記載の嫌気性排水処理方法。 The anaerobic wastewater treatment method according to claim 1, wherein in the first step, the CODcr volumetric load of the wastewater is 0.5 kg / m 3 / d or more and 5.0 kg / m 3 / d or less. 前記メタン菌凝集物の平均粒径が10μm以上450μm以下である、請求項1または2に記載の嫌気性排水処理方法。 The anaerobic wastewater treatment method according to claim 1 or 2, wherein the average particle size of the methanogen aggregate is 10 μm or more and 450 μm or less. 前記メタン菌凝集物がメタン菌グラニュールまたはメタン菌グラニュールの破砕物である、請求項1〜3のいずれか1項に記載の嫌気性排水処理方法。 The anaerobic wastewater treatment method according to any one of claims 1 to 3, wherein the methanogen aggregate is a methanogen granule or a crushed product of the methanogen granule. 前記担体がポリビニルアルコール系担体である、請求項1〜4のいずれか1項に記載の嫌気性排水処理方法。
The anaerobic wastewater treatment method according to any one of claims 1 to 4, wherein the carrier is a polyvinyl alcohol-based carrier.
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