JP6634862B2 - Wastewater treatment method and wastewater treatment device - Google Patents

Wastewater treatment method and wastewater treatment device Download PDF

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JP6634862B2
JP6634862B2 JP2016025837A JP2016025837A JP6634862B2 JP 6634862 B2 JP6634862 B2 JP 6634862B2 JP 2016025837 A JP2016025837 A JP 2016025837A JP 2016025837 A JP2016025837 A JP 2016025837A JP 6634862 B2 JP6634862 B2 JP 6634862B2
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intermittent aeration
aeration
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sludge
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JP2016172247A (en
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朋樹 川岸
朋樹 川岸
竹内　雅人
雅人 竹内
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Mitsubishi Chemical Corp
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C02F3/12—Activated sludge processes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/105—Phosphorus compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

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Description

本発明は、間欠曝気と膜分離活性汚泥法とを組み合わせた排水の処理方法、および排水の処理装置に関する。   The present invention relates to a wastewater treatment method and a wastewater treatment device that combine intermittent aeration and a membrane separation activated sludge method.

畜産、食品、化学工場などから排出される、窒素やリンの含有量が多い排水に対しては高度な窒素処理またはリン処理技術が求められている。
窒素処理としては、硝化液循環法、内性脱窒法、間欠曝気法などの方法が知られている。 For nitrogen and phosphorus-rich wastewater discharged from livestock, food, and chemical factories, advanced nitrogen treatment or phosphorus treatment technology is required.
As the nitrogen treatment, methods such as a nitrification liquid circulation method, an internal denitrification method, and an intermittent aeration method are known.

硝化液循環法では、窒素除去率が循環倍率に依存している。そのため、高い窒素除去率を得るためには循環倍率を高くする必要があるが、現実的な窒素除去率の限界は８０％程度とされている。
内性脱窒法では、硝化工程の後段でメタノール等の有機物を添加することによって脱窒処理を行うため、高い窒素除去率を得ることが可能である。しかし、メタノール添加によるコスト上昇が問題となっている。 In the nitrification liquid circulation method, the nitrogen removal rate depends on the circulation magnification. Therefore, in order to obtain a high nitrogen removal rate, it is necessary to increase the circulation ratio, but the practical limit of the nitrogen removal rate is about 80%.
In the internal denitrification method, a high nitrogen removal rate can be obtained because the denitrification treatment is performed by adding an organic substance such as methanol in the latter stage of the nitrification step. However, the increase in cost due to the addition of methanol is a problem.

一方、間欠曝気法は装置構成が簡便であり、硝化液循環することなく、高い窒素除去率を得ることができる。また、膜分離活性汚泥法と組み合わせた間欠曝気膜分離活性汚泥法も行われている（例えば、特許文献１、２参照）。
間欠曝気膜分離活性汚泥法では、例えば図１２に示すように、間欠曝気槽１０と膜分離槽２０とを備えた排水の処理装置２を用い、間欠曝気槽１０において活性汚泥により生物処理が行われ、膜分離槽２０において膜濾過が行われる。具体的には、窒素含有排水等の被処理水を間欠曝気槽１０に導き、間欠的に曝気処理を行う。曝気している間は硝化反応が進行し、曝気を停止している間は脱窒反応が進行する。間欠曝気槽１０内の生物処理水と活性汚泥とからなる汚泥含有水は膜分離槽２０に移送され、膜分離槽２０に設置された膜モジュール２２に備わる濾過膜により膜濾過される。また、膜濾過の継続に伴い活性汚泥が濃縮されてしまうため、通常、膜濾過を行っている間は、返送流路２７により膜分離槽２０から間欠曝気槽１０に膜分離槽２０内の汚泥含有水の一部を返送して、間欠曝気槽１０と膜分離槽２０との間で汚泥含有水を循環させる。 On the other hand, the intermittent aeration method has a simple apparatus configuration and can obtain a high nitrogen removal rate without circulating the nitrification liquid. Also, an intermittent aerated membrane separation activated sludge method combined with a membrane separation activated sludge method has been performed (for example, see Patent Documents 1 and 2).
In the intermittent aeration membrane separation activated sludge method, for example, as shown in FIG. 12, a wastewater treatment device 2 having an intermittent aeration tank 10 and a membrane separation tank 20 is used, and biological treatment is performed in the intermittent aeration tank 10 by activated sludge. Then, membrane filtration is performed in the membrane separation tank 20. Specifically, water to be treated such as nitrogen-containing wastewater is guided to the intermittent aeration tank 10 to perform intermittent aeration. The nitrification reaction proceeds during the aeration, and the denitrification reaction proceeds while the aeration is stopped. Sludge-containing water composed of biologically treated water and activated sludge in the intermittent aeration tank 10 is transferred to the membrane separation tank 20, and is subjected to membrane filtration by the filtration membrane provided in the membrane module 22 installed in the membrane separation tank 20. In addition, since activated sludge is concentrated with the continuation of the membrane filtration, the sludge in the membrane separation tank 20 is usually returned from the membrane separation tank 20 to the intermittent aeration tank 10 by the return flow path 27 during the membrane filtration. A part of the contained water is returned to circulate the sludge-containing water between the intermittent aeration tank 10 and the membrane separation tank 20.

特開平７−１００４８６号公報JP-A-7-100486 特開２００５−２１１７２８号公報JP 2005-217728 A

しかしながら、上述した間欠曝気膜分離活性汚泥法では、以下の問題があった。
通常、膜濾過中は膜モジュール２２の下方に設置された散気管２１によりエアを吐出して、膜分離槽２０内を曝気する。そのため、膜分離槽２０から間欠曝気槽１０に返送される汚泥含有水は、溶存酸素量（ＤＯ）が高い。
例えば図１３（ａ）に示すように、間欠曝気と膜分離活性汚泥法とを組合せた窒素含有排水の処理方法において、曝気停止中（脱窒中）にも汚泥含有水の循環を行い、膜分離槽２０から間欠曝気槽１０に高ＤＯの汚泥含有水を返送すると、脱窒に必要な無酸素状態が間欠曝気槽１０内において形成されにくく、十分に窒素が除去されなくなる。 However, the above-mentioned intermittent aeration membrane separation activated sludge method has the following problems.
Normally, during membrane filtration, air is discharged from the air diffuser 21 installed below the membrane module 22 to aerate the inside of the membrane separation tank 20. Therefore, the sludge-containing water returned from the membrane separation tank 20 to the intermittent aeration tank 10 has a high dissolved oxygen amount (DO).
For example, as shown in FIG. 13 (a), in a method for treating nitrogen-containing wastewater in which intermittent aeration and a membrane separation activated sludge method are combined, the sludge-containing water is circulated even during aeration stop (during denitrification), and When the high DO sludge-containing water is returned from the separation tank 20 to the intermittent aeration tank 10, the oxygen-free state required for denitrification is not easily formed in the intermittent aeration tank 10, and nitrogen cannot be sufficiently removed.

無酸素状態を維持するためには、図１３（ｂ）に示すように、曝気停止中に膜濾過も停止して汚泥含有水の循環を止めればよい。
しかし、曝気停止中に膜濾過も停止するとその分、膜濾過時間が短くなるため、処理効率が低下する。処理効率を維持するために濾過膜の膜面積を大きくすることも考えられるが、コスト上昇となるため経済的ではない。
また、リン処理を行う場合も嫌気条件が必須であるため、上記と同様の問題が生じる。 In order to maintain the anoxic state, as shown in FIG. 13 (b), the membrane filtration may be stopped to stop the circulation of the sludge-containing water while the aeration is stopped.
However, if the membrane filtration is also stopped while the aeration is stopped, the membrane filtration time is shortened accordingly, and the treatment efficiency is reduced. Although it is conceivable to increase the membrane area of the filtration membrane in order to maintain the processing efficiency, it is not economical because the cost increases.
Also, when performing the phosphorus treatment, an anaerobic condition is indispensable, and thus the same problem as described above occurs.

本発明は上記事情に鑑みてなされたもので、効率的に窒素処理やリン処理と、膜濾過処理とを達成できる排水の処理方法および排水の処理装置の提供を課題とする。   The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a wastewater treatment method and a wastewater treatment device capable of efficiently performing a nitrogen treatment, a phosphorus treatment, and a membrane filtration treatment.

本発明は、以下の態様を有する。
［１］ 被処理水を間欠曝気槽に導き、曝気と曝気停止とを繰り返して、活性汚泥により生物処理する間欠曝気工程と、間欠曝気槽内の生物処理水と活性汚泥とからなる汚泥含有水を膜分離槽に移送して膜濾過する膜濾過工程と、膜分離槽から間欠曝気槽に、膜分離槽内の汚泥含有水の一部を返送させる返送工程とを有する、間欠曝気膜分離活性汚泥法により排水を処理する方法において、前記間欠曝気槽を複数用い、排水処理を行っている間は１槽以上の間欠曝気槽が曝気状態となるように、各間欠曝気槽の運転を制御し、汚泥含有水の移送および返送を曝気状態にある間欠曝気槽と膜分離槽との間で行う、排水の処理方法。
［２］ 間欠曝気槽の数をｎとし、間欠曝気工程における曝気時間をｔ１、曝気停止時間をｔ２とし、ｔ１とｔ２の最大公約数をａとしたときに、下記式（１）を満たす、［１］に記載の排水の処理方法。
ｎ＝ｔ１／ａ＋ｔ２／ａ ・・・（１）
［３］ 曝気状態にある間欠曝気槽と膜分離槽との間で行われる汚泥含有水の移送および返送の開始を、その間欠曝気槽での曝気開始から遅らせる、［２］に記載の排水の処理方法。
［４］ 全ての間欠曝気槽の運転のタイミングが異なるように、各間欠曝気槽の曝気を制御する、［１］〜［３］のいずれか１つに記載の排水の処理方法。 The present invention has the following aspects.
[1] Intermittent aeration step of introducing treated water to an intermittent aeration tank, repeating aeration and stopping aeration, and biologically treating with activated sludge, and sludge-containing water comprising biologically treated water and activated sludge in the intermittent aeration tank A membrane filtration step of transferring the wastewater to a membrane separation tank and performing membrane filtration, and a return step of returning a part of the sludge-containing water in the membrane separation tank from the membrane separation tank to the intermittent aeration tank. In the method for treating wastewater by the sludge method, a plurality of the intermittent aeration tanks are used, and the operation of each intermittent aeration tank is controlled so that one or more intermittent aeration tanks are in an aerated state during the wastewater treatment. And a method for treating wastewater, wherein transfer and return of sludge-containing water are performed between an intermittent aeration tank and a membrane separation tank in an aerated state.
[2] When the number of intermittent aeration tanks is n, the aeration time in the intermittent aeration step is t1, the aeration stop time is t2, and the greatest common divisor of t1 and t2 is a, the following equation (1) is satisfied: The method for treating wastewater according to [1].
n = t1 / a + t2 / a (1)
[3] The drainage according to [2], wherein the start of the transfer and return of the sludge-containing water performed between the intermittent aeration tank and the membrane separation tank in the aerated state is delayed from the start of the aeration in the intermittent aeration tank. Processing method.
[4] The method for treating wastewater according to any one of [1] to [3], wherein the aeration of each intermittent aeration tank is controlled such that the operation timings of all the intermittent aeration tanks are different.

［５］ 被処理水が導かれ、曝気と曝気停止とを繰り返して、活性汚泥により生物処理する間欠曝気槽と、間欠曝気槽内の生物処理水と活性汚泥とからなる汚泥含有水を膜濾過する膜分離槽と、膜分離槽から間欠曝気槽に、膜分離槽内の汚泥含有水の一部を返送させる返送手段とを備えた、間欠曝気膜分離活性汚泥法により排水を処理する装置において、前記間欠曝気槽を複数備え、排水処理を行っている間は１槽以上の間欠曝気槽が曝気状態となるように、各間欠曝気槽の運転が制御され、汚泥含有水の移送および返送が曝気状態にある間欠曝気槽と膜分離槽との間で行われる、排水の処理装置。
［６］ 全ての間欠曝気槽の運転のタイミングが異なるように、各間欠曝気槽の曝気が制御されている、［５］に記載の排水の処理装置。 [5] Membrane filtration of intermittent aeration tanks for biological treatment with activated sludge, and sludge-containing water consisting of biologically treated water and activated sludge in the intermittent aeration tank, through which the water to be treated is guided and aeration and aeration stop are repeated. And a return means for returning a part of the sludge-containing water in the membrane separation tank from the membrane separation tank to the intermittent aeration tank. The operation of each of the intermittent aeration tanks is controlled so that one or more intermittent aeration tanks are in an aerated state while the wastewater treatment is performed, and the transfer and return of the sludge-containing water are performed. A wastewater treatment device that is performed between an intermittent aeration tank and a membrane separation tank in an aerated state.
[6] The wastewater treatment apparatus according to [5], wherein the aeration of each intermittent aeration tank is controlled such that the operation timings of all the intermittent aeration tanks are different.

本発明の排水の処理方法によれば、効率的に窒素処理やリン処理と、膜濾過処理とを達成できる。
また、本発明の排水の処理装置によれば、効率的に窒素処理やリン処理と、膜濾過処理とを達成できる。 According to the method for treating wastewater of the present invention, a nitrogen treatment, a phosphorus treatment, and a membrane filtration treatment can be efficiently achieved.
Further, according to the wastewater treatment apparatus of the present invention, nitrogen treatment and phosphorus treatment and membrane filtration treatment can be efficiently achieved.

本発明の排水の処理装置の一例を示す概略構成図である。It is a schematic structure figure showing an example of the processing equipment of the waste water of the present invention. ２槽の間欠曝気槽の運転のタイミングの一例を示すタイムチャートである。It is a time chart which shows an example of operation timing of two intermittent aeration tanks. ３槽の間欠曝気槽の運転のタイミングの一例を示すタイムチャートである。It is a time chart which shows an example of the operation timing of three intermittent aeration tanks. ４槽の間欠曝気槽の運転のタイミングの一例を示すタイムチャートである。It is a time chart which shows an example of the operation timing of four intermittent aeration tanks. ２槽の間欠曝気槽の運転のタイミングの他の例を示すタイムチャートである。It is a time chart which shows another example of operation timing of two tanks intermittent aeration tanks. ３槽の間欠曝気槽の運転のタイミングの他の例を示すタイムチャートである。It is a time chart which shows another example of operation timing of three tanks of an intermittent aeration tank. ２槽の間欠曝気槽の運転のタイミングの他の例を示すタイムチャートである。It is a time chart which shows another example of operation timing of two tanks intermittent aeration tanks. ３槽の間欠曝気槽の運転のタイミングの他の例を示すタイムチャートである。It is a time chart which shows another example of operation timing of three tanks of an intermittent aeration tank. ２槽の間欠曝気槽の運転のタイミングの他の例を示すタイムチャートである。It is a time chart which shows another example of operation timing of two tanks intermittent aeration tanks. ３槽の間欠曝気槽の運転のタイミングの他の例を示すタイムチャートである。It is a time chart which shows another example of operation timing of three tanks of an intermittent aeration tank. ５槽の間欠曝気槽の運転のタイミングの一例を示すタイムチャートである。It is a time chart which shows an example of operation timing of five intermittent aeration tanks. 従来の排水の処理装置の一例を示す概略構成図である。It is a schematic structure figure showing an example of the conventional waste water treatment equipment. （ａ）は１槽の間欠曝気槽の運転のタイミングの一例を示すタイムチャートであり、（ｂ）は１槽の間欠曝気槽の運転のタイミングの他の例を示すタイムチャートである。(A) is a time chart showing an example of the operation timing of one intermittent aeration tank, and (b) is a time chart showing another example of the operation timing of one intermittent aeration tank.

以下、本発明について詳細に説明する。
［排水の処理装置］
図１は、本発明の排水の処理装置の一例を示す概略構成図である。
図１に示す排水の処理装置１は、２槽の間欠曝気槽１０と、１槽の膜分離槽２０とを具備する。以下、２槽の間欠曝気槽１０のうち、一方を「第一の間欠曝気槽」といい、他方を「第二の間欠曝気槽」ともいう。 Hereinafter, the present invention will be described in detail.
[Effluent treatment equipment]
FIG. 1 is a schematic configuration diagram showing an example of a wastewater treatment device of the present invention.
The wastewater treatment apparatus 1 shown in FIG. 1 includes two intermittent aeration tanks 10 and one membrane separation tank 20. Hereinafter, one of the two intermittent aeration tanks 10 is also referred to as a “first intermittent aeration tank”, and the other is also referred to as a “second intermittent aeration tank”.

間欠曝気槽１０は、曝気と曝気停止とを繰り返して、活性汚泥の作用により工業排水などの被処理水を生物処理し、生物処理水とするための槽である。
間欠曝気槽１０は、槽内を間欠曝気するための散気管１１と、槽内を攪拌するための攪拌手段１２を備える。 The intermittent aeration tank 10 is a tank for repeatedly performing aeration and stopping the aeration and biologically treating the water to be treated such as industrial wastewater by the action of activated sludge to obtain biologically treated water.
The intermittent aeration tank 10 includes an air diffuser 11 for intermittently aerating the inside of the tank, and a stirring unit 12 for stirring the inside of the tank.

散気管１１は、間欠曝気槽１０の底部近傍に設置されている。
散気管１１には、散気管１１にエアを供給する導入管１３が接続され、導入管１３にブロア１４が設置されている。ブロア１４には、ブロア制御装置１５が接続されている。
散気管１１としては、ブロア１４から供給されるエアを上方へ吐出できるものであれば特に限定されないが、例えば、穴あきの単管や、メンブレンタイプのものが挙げられる。 The air diffuser 11 is installed near the bottom of the intermittent aeration tank 10.
An inlet pipe 13 for supplying air to the diffuser pipe 11 is connected to the diffuser pipe 11, and a blower 14 is installed in the inlet pipe 13. A blower control device 15 is connected to the blower 14.
The air diffuser 11 is not particularly limited as long as the air supplied from the blower 14 can be discharged upward, and examples thereof include a perforated single tube and a membrane type.

間欠曝気槽１０には、被処理水流路１６、および汚泥含有水流路１７が接続されている。
被処理水流路１６は、被処理水を貯留する原水タンク（図示略）から被処理水を間欠曝気槽１０に供給するための流路である。被処理水流路１６には原水ポンプ１８が設置されている。
汚泥含有水流路１７は、間欠曝気槽１０から引き抜かれた生物処理水と活性汚泥とからなる汚泥含有水を膜分離槽２０に移送するための流路である。 The intermittent aeration tank 10 is connected to a water passage 16 to be treated and a sludge-containing water passage 17.
The treated water flow path 16 is a flow path for supplying the treated water to the intermittent aeration tank 10 from a raw water tank (not shown) that stores the treated water. A raw water pump 18 is provided in the water passage 16 to be treated.
The sludge-containing water flow path 17 is a flow path for transferring the sludge-containing water composed of the biologically treated water drawn from the intermittent aeration tank 10 and the activated sludge to the membrane separation tank 20.

膜分離槽２０は、間欠曝気槽１０より移送された汚泥含有水を膜濾過して、汚泥と透過水（処理水）とを膜分離（固液分離）するための槽である。
膜分離槽２０は、槽内を曝気するための散気管２１と、濾過膜を備える膜モジュール２２とを備える。 The membrane separation tank 20 is a tank for subjecting the sludge-containing water transferred from the intermittent aeration tank 10 to membrane filtration and separating the sludge from permeated water (treated water) by membrane (solid-liquid separation).
The membrane separation tank 20 includes an air diffuser 21 for aerating the inside of the tank, and a membrane module 22 having a filtration membrane.

散気管２１は、膜分離槽２０内の膜モジュール２２の下方に設置されている。
散気管２１には、散気管２１にエアを供給する導入管２３が接続され、導入管２３にブロア２４が設置されている。
散気管２１としては、ブロア２４から供給されるエアを上方へ吐出できるものであれば特に限定されないが、例えば、穴あきの単管や、メンブレンタイプのものが挙げられる。 The air diffuser 21 is installed below the membrane module 22 in the membrane separation tank 20.
An inlet pipe 23 for supplying air to the diffuser pipe 21 is connected to the diffuser pipe 21, and a blower 24 is installed in the inlet pipe 23.
The air diffuser 21 is not particularly limited as long as the air supplied from the blower 24 can be discharged upward, and examples thereof include a perforated single tube and a membrane type.

膜モジュール２２は、膜分離槽２０内に配置されている。膜モジュール２２では、汚泥含有水が濾過膜で膜処理される。
濾過膜としては、濾過能を有するものであれば特に限定されないが、例えば、中空糸膜、平膜、チューブラ膜、モノリス型膜などが挙げられる。これらの中でも、容積充填率が高いことから、中空糸膜が好ましい。 The membrane module 22 is disposed in the membrane separation tank 20. In the membrane module 22, sludge-containing water is subjected to membrane treatment by a filtration membrane.
The filtration membrane is not particularly limited as long as it has a filtration ability, and examples thereof include a hollow fiber membrane, a flat membrane, a tubular membrane, and a monolith membrane. Among these, hollow fiber membranes are preferred because of their high volume filling factor.

濾過膜として中空糸膜を用いる場合、その材質としては、例えば、セルロース、ポリオレフィン、ポリスルホン、ポリフッ化ビニリデンフロライド（ＰＶＤＦ）、ポリ四フッ化エチレン（ＰＴＦＥ）などが挙げられる。これらの中でも、中空糸膜の材質としては、耐薬品性やｐＨ変化に強い点から、ＰＶＤＦ、ＰＴＦＥが好ましい。
濾過膜としてモノリス型膜を用いる場合は、セラミック製の膜を用いることが好ましい。 When a hollow fiber membrane is used as the filtration membrane, examples of the material include cellulose, polyolefin, polysulfone, polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE). Among these, PVDF and PTFE are preferable as the material of the hollow fiber membrane from the viewpoint of chemical resistance and resistance to pH change.
When a monolith type membrane is used as the filtration membrane, it is preferable to use a ceramic membrane.

濾過膜に形成される微細孔の平均孔径としては、一般に限外濾過膜と呼ばれる膜で０．００１〜０．１μｍ程度であり、一般に精密濾過膜と呼ばれる膜で０．１〜1μｍ程度である。本発明においては平均孔径が上記範囲内である濾過膜を用いることが好ましい。   The average pore size of the micropores formed in the filtration membrane is about 0.001 to 0.1 μm for a membrane generally called an ultrafiltration membrane, and about 0.1 to 1 μm for a membrane generally called a microfiltration membrane. . In the present invention, it is preferable to use a filtration membrane having an average pore diameter within the above range.

膜モジュール２２には、透過水を排出する透過水流路２５が接続され、該透過水流路２５に膜濾過ポンプ２６が設置されている。これにより、膜モジュール２２の濾過膜を透過した透過水を膜分離槽２０から排出できるようになっている。   The membrane module 22 is connected to a permeated water channel 25 for discharging permeated water, and a membrane filtration pump 26 is installed in the permeated water channel 25. Thereby, the permeated water that has passed through the filtration membrane of the membrane module 22 can be discharged from the membrane separation tank 20.

また、膜分離槽２０には、返送手段として返送流路２７が接続され、該返送流路２７に循環ポンプ２８が設置されている。これにより、膜分離槽２０内の汚泥含有水の一部を膜分離槽２０から間欠曝気槽１０に返送し、間欠曝気槽１０と膜分離槽２０との間で汚泥含有水の移送および返送（以下、移送および返送を併せて「循環」ともいう）ができるようになっている。   Further, a return flow path 27 is connected to the membrane separation tank 20 as return means, and a circulation pump 28 is provided in the return flow path 27. Thereby, a part of the sludge-containing water in the membrane separation tank 20 is returned from the membrane separation tank 20 to the intermittent aeration tank 10, and the sludge-containing water is transferred and returned between the intermittent aeration tank 10 and the membrane separation tank 20 ( Hereinafter, transfer and return are collectively referred to as “circulation”).

なお、図１中、符号１３ａ、１３ｂ、１６ａ、１６ｂ、２７ａ、２７ｂは、それぞれ開閉バルブである。   In FIG. 1, reference numerals 13a, 13b, 16a, 16b, 27a, and 27b denote on-off valves, respectively.

本発明の排水の処理装置は、図示例のものに限定されない。図示例の排水の処理装置１は間欠曝気槽１０を２槽備えるものであるが、間欠曝気槽１０は３槽以上であってもよい。
また、図示例の排水の処理装置１は、２槽の間欠曝気槽１０で１つのブロア１４を共有しているが、各間欠曝気槽１０にブロア１４を個々に設置してもよい。 The wastewater treatment apparatus of the present invention is not limited to the illustrated example. Although the wastewater treatment apparatus 1 in the illustrated example includes two intermittent aeration tanks 10, three or more intermittent aeration tanks may be provided.
Further, in the illustrated wastewater treatment apparatus 1, one blower 14 is shared by two intermittent aeration tanks 10, but the blowers 14 may be individually installed in each intermittent aeration tank 10.

また、図示例の排水の処理装置１では、間欠曝気槽１０から膜分離槽２０への汚泥含有水の移送はオーバーフローとし、膜分離槽２０から間欠曝気槽１０への汚泥含有水の返送は循環ポンプ２８を用いているが、逆でもよい。すなわち、膜分離槽２０から間欠曝気槽１０への汚泥含有水の返送をオーバーフローとし、間欠曝気槽１０から膜分離槽２０への汚泥含有水の移送に循環ポンプ２８を用いてもよい。   In the wastewater treatment apparatus 1 shown in the figure, the transfer of the sludge-containing water from the intermittent aeration tank 10 to the membrane separation tank 20 is set to overflow, and the return of the sludge-containing water from the membrane separation tank 20 to the intermittent aeration tank 10 is circulated. Although the pump 28 is used, the reverse may be used. That is, the return of the sludge-containing water from the membrane separation tank 20 to the intermittent aeration tank 10 may be an overflow, and the circulation pump 28 may be used to transfer the sludge-containing water from the intermittent aeration tank 10 to the membrane separation tank 20.

また、生物処理によって間欠曝気槽１０中の活性汚泥のｐＨが変動する場合がある。そのため、アルカリや酸を添加して活性汚泥のｐＨを生物処理に適した中性付近に調整するためのｐＨ調整手段を間欠曝気槽１０に設けてもよい。   Further, the pH of the activated sludge in the intermittent aeration tank 10 may fluctuate due to biological treatment. Therefore, a pH adjusting means for adjusting the pH of the activated sludge to near neutrality suitable for biological treatment by adding an alkali or an acid may be provided in the intermittent aeration tank 10.

［排水の処理方法］
＜第一の実施形態＞
次に、本発明の排水の処理方法の第一の実施形態例について、被処理水として窒素を含む排水を例にとり、図１および図２に示すタイムチャートを参照しながら説明する。
なお、以下に説明する排水の処理方法は、間欠曝気槽１０が２槽の場合であるが、間欠曝気槽１０は３槽以上であってもよい。 [Wastewater treatment method]
<First embodiment>
Next, a first embodiment of a method for treating wastewater of the present invention will be described with reference to time charts shown in FIGS. 1 and 2, taking wastewater containing nitrogen as an example of water to be treated.
Although the method for treating wastewater described below is a case where the number of intermittent aeration tanks 10 is two, the number of intermittent aeration tanks 10 may be three or more.

本発明の第一の実施形態の排水の処理方法は、被処理水を間欠曝気槽１０に導き、曝気と曝気停止とを繰り返して、活性汚泥により生物処理する間欠曝気工程と、間欠曝気槽１０内の生物処理水と活性汚泥とからなる汚泥含有水を膜分離槽２０に移送して膜濾過する膜濾過工程と、膜分離槽２０から間欠曝気槽１０に、膜分離槽２０内の汚泥含有水の一部を返送させる返送工程とを有する、間欠曝気膜分離活性汚泥法により排水を処理する方法である。   The method for treating wastewater according to the first embodiment of the present invention includes an intermittent aeration step in which water to be treated is guided to an intermittent aeration tank 10, and aeration and aeration stop are repeated to biologically treat with activated sludge. Membrane filtration step of transferring sludge-containing water consisting of biologically treated water and activated sludge to the membrane separation tank 20 and membrane-filtering the sludge-containing water from the membrane separation tank 20 to the intermittent aeration tank 10, And a return step of returning part of the water, wherein the wastewater is treated by an intermittent aeration membrane separation activated sludge method.

本発明の処理対象となる被処理水は、例えば、畜産、食品、化学工場などから排出される、窒素やリンの含有量が多い排水である。
被処理水は、予め原水タンク（図示略）に貯留されており、被処理水の量的および質的な変動を吸収し、さらにスクリーンを経て粗大な夾雑物を除去した後に、間欠曝気槽１０に導かれるのが好ましい。 The treated water to be treated in the present invention is, for example, wastewater having a high content of nitrogen and phosphorus discharged from livestock, food, chemical factories, and the like.
The water to be treated is stored in a raw water tank (not shown) in advance, absorbs the quantitative and qualitative fluctuations of the water to be treated, and further removes coarse impurities through a screen. Is preferably led to

各間欠曝気槽１０の汚泥濃度はＭＬＳＳとして６，０００〜２０，０００ｍｇ／Ｌの間で適宜設定することが好ましい。ＭＬＳＳが６，０００ｍｇ／Ｌ未満であると、生物処理効率の低下や膜閉塞の原因となることがある。
ＭＬＳＳは高濃度である方が生物処理効率の観点では好ましいが、２０，０００ｍｇ／Ｌを超えると汚泥粘度が過剰に高くなり、膜モジュール２２の濾過膜への汚泥固着の原因となることがある。 It is preferable that the sludge concentration of each intermittent aeration tank 10 is appropriately set between 6,000 and 20,000 mg / L as MLSS. If the MLSS is less than 6,000 mg / L, it may cause a decrease in biological treatment efficiency or membrane blockage.
The higher the concentration of MLSS, the better in terms of biological treatment efficiency, but if it exceeds 20,000 mg / L, the viscosity of sludge becomes excessively high, which may cause the sludge to adhere to the filtration membrane of the membrane module 22. .

図２に示すタイムチャートでは、まず、第一の間欠曝気槽の曝気を停止し、被処理水を導く（曝気停止工程）。一方、第二の間欠曝気槽には被処理水を流入せずに曝気を開始する（曝気工程）。さらに、第二の間欠曝気槽と膜分離槽との間で汚泥含有水を循環させつつ、膜分離槽において汚泥含有水を膜濾過する。
所定の時間が経過したら、第二の間欠曝気槽の曝気を停止し、被処理水を導く（曝気停止工程）。一方、第一の間欠曝気槽には被処理水を流入せずに曝気を開始する（曝気工程）。さらに、第一の間欠曝気槽と膜分離槽との間で汚泥含有水を循環させつつ、膜分離槽において汚泥含有水を膜濾過する。
このように、所定の時間が経過する度に、第一の間欠曝気槽および第二の間欠曝気槽において曝気と曝気停止とを繰り返す。
以下、間欠曝気、膜濾過、および循環の流れを具体的に説明する。 In the time chart shown in FIG. 2, first, the aeration of the first intermittent aeration tank is stopped, and the water to be treated is guided (aeration stopping step). On the other hand, aeration is started without flowing the water to be treated into the second intermittent aeration tank (aeration step). Further, while the sludge-containing water is circulated between the second intermittent aeration tank and the membrane separation tank, the sludge-containing water is subjected to membrane filtration in the membrane separation tank.
After a lapse of a predetermined time, the aeration of the second intermittent aeration tank is stopped, and the water to be treated is guided (aeration stopping step). On the other hand, aeration is started without flowing the water to be treated into the first intermittent aeration tank (aeration step). Furthermore, while circulating the sludge-containing water between the first intermittent aeration tank and the membrane separation tank, the sludge-containing water is subjected to membrane filtration in the membrane separation tank.
Thus, each time a predetermined time elapses, the aeration and the stop of the aeration are repeated in the first intermittent aeration tank and the second intermittent aeration tank.
Hereinafter, the flow of intermittent aeration, membrane filtration, and circulation will be specifically described.

まず、開閉バルブ１３ａを「閉」とし、第一の間欠曝気槽１０ａの曝気を停止するとともに、開閉バルブ１３ｂを「開」とし、ブロア１４を作動させて散気管１１からエアを吐出し、第二の間欠曝気槽１０ｂの曝気を開始する。また、開閉バルブ１６ａを「開」とし、開閉バルブ１６ｂを「閉」とし、原水ポンプ１８を作動させて原水タンク（図示略）から第一の間欠曝気槽１０ａのみに被処理水を供給する（原水流入）。また、ブロア２４および膜濾過ポンプ２６を作動させ、オーバーフローにより第二の間欠曝気槽１０ｂから膜分離槽２０に移送された汚泥含有水を膜モジュール２２により膜濾過し、透過水を膜分離槽２０から排出する。同時に、開閉バルブ２７ａを「閉」とし、開閉バルブ２７ｂを「開」とし、循環ポンプ２８を作動させて、膜分離槽２０から第二の間欠曝気槽１０ｂに膜分離槽２０内の汚泥含有水の一部を返送して、第二の間欠曝気槽１０ｂと膜分離槽２０との間で汚泥含有水を循環させる（汚泥含有水の循環）。
被処理水は、曝気停止工程の開始直後に短時間で第一の間欠曝気槽１０ａに供給されることが好ましい。これは、被処理水の供給時間が短くなるほど、曝気停止工程において生じる脱窒反応の時間が長くなり、より効率よく窒素除去を行うことができるためである。そのため、予め設定された所定量の被処理水が第一の間欠曝気槽１０ａに供給された後は、原水ポンプ１８を止めて、被処理水の供給を停止することが好ましい。 First, the opening / closing valve 13a is closed, the aeration of the first intermittent aeration tank 10a is stopped, the opening / closing valve 13b is opened, and the blower 14 is operated to discharge air from the air diffuser 11; Aeration of the two intermittent aeration tanks 10b is started. Further, the open / close valve 16a is set to “open”, the open / close valve 16b is set to “closed”, and the raw water pump 18 is operated to supply the water to be treated from the raw water tank (not shown) to only the first intermittent aeration tank 10a ( Raw water inflow). Further, the blower 24 and the membrane filtration pump 26 are operated, and the sludge-containing water transferred from the second intermittent aeration tank 10b to the membrane separation tank 20 by overflow is subjected to membrane filtration by the membrane module 22. Discharged from At the same time, the opening / closing valve 27a is closed, the opening / closing valve 27b is opened, and the circulation pump 28 is operated to transfer the sludge-containing water in the membrane separation tank 20 from the membrane separation tank 20 to the second intermittent aeration tank 10b. Is returned to circulate the sludge-containing water between the second intermittent aeration tank 10b and the membrane separation tank 20 (circulation of the sludge-containing water).
The water to be treated is preferably supplied to the first intermittent aeration tank 10a in a short time immediately after the start of the aeration stop step. This is because the shorter the supply time of the water to be treated, the longer the time of the denitrification reaction generated in the aeration stopping step, and the more efficient the nitrogen removal. Therefore, after a predetermined amount of the water to be treated is supplied to the first intermittent aeration tank 10a, it is preferable to stop the raw water pump 18 and stop the supply of the water to be treated.

第一の間欠曝気槽１０ａにおける曝気停止工程では、槽内に導いた被処理水に含まれる有機物を電子供与体として、活性汚泥に含まれる微生物によって硝酸又は亜硝酸が窒素ガスにまで還元される（脱窒反応）。この曝気停止による脱窒反応によって、被処理水中の有機物および硝酸と亜硝酸の濃度が低減する。
有機物の一部は、水と二酸化炭素にまで分解される。また、有機物の一部は、活性汚泥を構成する微生物の増殖に使用され、最終的に余剰汚泥となって排出される。 In the aeration stop step in the first intermittent aeration tank 10a, nitric acid or nitrous acid is reduced to nitrogen gas by microorganisms contained in the activated sludge using organic matter contained in the water to be treated introduced into the tank as an electron donor. (Denitrification reaction). By the denitrification reaction caused by stopping the aeration, the concentrations of organic substances and nitric acid and nitrous acid in the water to be treated are reduced.
Some organic matter is broken down into water and carbon dioxide. Further, a part of the organic matter is used for the propagation of microorganisms constituting the activated sludge, and is finally discharged as surplus sludge.

曝気停止工程では活性汚泥が沈殿するため、攪拌手段１２によって槽内の活性汚泥を攪拌することが好ましい。また、攪拌手段１２による攪拌の代わりに、曝気停止工程であっても極めて短時間の曝気を行うことで活性汚泥を攪拌してもよい。ただし、槽内の無酸素状態を良好に維持できる点で、攪拌手段１２により活性汚泥を攪拌することが好ましい。
また、脱窒反応により活性汚泥のｐＨが変動する場合がある。そのような場合には、ｐＨ調整手段（図示略）によりアルカリや酸を添加し、活性汚泥のｐＨを生物処理に適した中性付近に調整することが好ましい。 Since activated sludge precipitates in the aeration stop step, it is preferable that the activated sludge in the tank is stirred by the stirring means 12. Further, instead of the stirring by the stirring means 12, even in the aeration stopping step, the activated sludge may be stirred by performing the aeration for an extremely short time. However, it is preferable that the activated sludge is stirred by the stirring means 12 in that the oxygen-free state in the tank can be favorably maintained.
Further, the pH of the activated sludge may fluctuate due to the denitrification reaction. In such a case, it is preferable to add an alkali or an acid by a pH adjusting means (not shown) to adjust the pH of the activated sludge to near neutrality suitable for biological treatment.

一方、第二の間欠曝気槽１０ｂにおける曝気工程では、曝気工程を開始する前に槽内に導かれていた被処理水に含まれる有機物および窒素成分が、曝気により供給された空気中の酸素によって酸化される（硝化反応）。
窒素成分は、タンパク質、アミノ酸、尿素などの有機体窒素；アンモニア、硝酸、亜硝酸などの無機体窒素として被処理水に含まれている。タンパク質などの有機体窒素は生物的な加水分解や酸化作用によってアンモニアとなる。アンモニアはさらに活性汚泥に含まれるアンモニア酸化細菌、亜硝酸酸化細菌等の微生物によって、硝酸および亜硝酸にまで酸化される。そのため、活性汚泥中のアンモニアおよび有機物の濃度は、曝気工程の時間の経過とともに低くなる。 On the other hand, in the aeration step in the second intermittent aeration tank 10b, the organic matter and the nitrogen component contained in the water to be treated that have been introduced into the tank before the start of the aeration step are changed by oxygen in the air supplied by the aeration. It is oxidized (nitrification reaction).
The nitrogen component is contained in the water to be treated as organic nitrogen such as protein, amino acid and urea; and inorganic nitrogen such as ammonia, nitric acid and nitrous acid. Organic nitrogen such as protein is converted to ammonia by biological hydrolysis or oxidative action. Ammonia is further oxidized to nitric acid and nitrite by microorganisms such as ammonia-oxidizing bacteria and nitrite-oxidizing bacteria contained in the activated sludge. Therefore, the concentrations of ammonia and organic substances in the activated sludge decrease with the lapse of time in the aeration step.

曝気工程では硝化反応により活性汚泥のｐＨが変動する場合がある。そのような場合には、ｐＨ調整手段（図示略）によりアルカリや酸を添加し、活性汚泥のｐＨを生物処理に適した中性付近に調整することが好ましい。   In the aeration step, the pH of the activated sludge may fluctuate due to the nitrification reaction. In such a case, it is preferable to add an alkali or an acid by a pH adjusting means (not shown) to adjust the pH of the activated sludge to near neutrality suitable for biological treatment.

曝気工程の間は、第二の間欠曝気槽１０ｂと膜分離槽２０との間で汚泥含有水を循環させる。第二の間欠曝気槽１０ｂから膜分離槽２０へ移送された汚泥含有水は、膜分離槽２０の膜モジュール２２により膜濾過される。膜モジュール２２の濾過膜を透過した透過水は、透過水流路２５を通って膜分離槽２０から排出される。また、膜分離槽２０内の汚泥含有水の一部は第二の間欠曝気槽１０ｂに返送される。
間欠曝気槽１０と膜分離槽２０との間を循環する汚泥含有水の流量は、膜濾過される汚泥含有水の量に対して２〜５倍程度が好ましい。２倍未満であると膜分離槽２０内で活性汚泥が過剰に濃縮する傾向にあり、５倍を超えると循環に要する動力が過剰となり、運転コストが増大する傾向にある。 During the aeration step, the sludge-containing water is circulated between the second intermittent aeration tank 10b and the membrane separation tank 20. The sludge-containing water transferred from the second intermittent aeration tank 10b to the membrane separation tank 20 is subjected to membrane filtration by the membrane module 22 of the membrane separation tank 20. The permeated water that has passed through the filtration membrane of the membrane module 22 is discharged from the membrane separation tank 20 through the permeated water channel 25. Further, a part of the sludge-containing water in the membrane separation tank 20 is returned to the second intermittent aeration tank 10b.
The flow rate of the sludge-containing water circulating between the intermittent aeration tank 10 and the membrane separation tank 20 is preferably about 2 to 5 times the amount of the sludge-containing water subjected to membrane filtration. If it is less than twice, activated sludge tends to be excessively concentrated in the membrane separation tank 20, and if it is more than five times, the power required for circulation becomes excessive, and the operating cost tends to increase.

所定の時間が経過したら、開閉バルブ１３ｂを「閉」とし、第二の間欠曝気槽１０ｂの曝気を停止するとともに、開閉バルブ１３ａを「開」とし、散気管１１からエアを吐出し、第一の間欠曝気槽１０ａの曝気を開始する。また、開閉バルブ１６ａを「閉」とし、開閉バルブ１６ｂを「開」とし、原水ポンプ１８を作動させて原水タンク（図示略）から第二の間欠曝気槽１０ｂのみに被処理水を供給する（原水流入）。また、オーバーフローにより第一の間欠曝気槽１０ａから膜分離槽２０に移送された汚泥含有水を膜モジュール２２により膜濾過し、透過水を膜分離槽２０から排出する。同時に、開閉バルブ２７ａを「開」とし、開閉バルブ２７ｂを「閉」とし、膜分離槽２０から第一の間欠曝気槽１０ａに膜分離槽２０内の汚泥含有水の一部を返送して、第一の間欠曝気槽１０ａと膜分離槽２０との間で汚泥含有水を循環させる（汚泥含有水の循環）。
被処理水は、曝気停止工程の開始直後に短時間で第二の間欠曝気槽１０ｂに供給されることが好ましい。そのため、予め設定された所定量の被処理水が第二の間欠曝気槽１０ｂに供給された後は、原水ポンプ１８を止めて、被処理水の供給を停止することが好ましい。
なお、排水処理中、ブロア１４、２４、膜濾過ポンプ２６および循環ポンプ２８は作動させたままである。 After a lapse of a predetermined time, the opening / closing valve 13b is closed, the aeration of the second intermittent aeration tank 10b is stopped, and the opening / closing valve 13a is opened, and air is discharged from the diffuser pipe 11, The aeration of the intermittent aeration tank 10a is started. Further, the open / close valve 16a is set to “closed”, the open / close valve 16b is set to “open”, and the raw water pump 18 is operated to supply the water to be processed from the raw water tank (not shown) to only the second intermittent aeration tank 10b ( Raw water inflow). Further, the sludge-containing water transferred from the first intermittent aeration tank 10a to the membrane separation tank 20 due to overflow is subjected to membrane filtration by the membrane module 22, and the permeated water is discharged from the membrane separation tank 20. At the same time, the open / close valve 27a is set to “open”, the open / close valve 27b is set to “closed”, and a part of the sludge-containing water in the membrane separation tank 20 is returned from the membrane separation tank 20 to the first intermittent aeration tank 10a. The sludge-containing water is circulated between the first intermittent aeration tank 10a and the membrane separation tank 20 (circulation of sludge-containing water).
The water to be treated is preferably supplied to the second intermittent aeration tank 10b in a short time immediately after the start of the aeration stop step. Therefore, after a predetermined amount of water to be treated is supplied to the second intermittent aeration tank 10b, it is preferable to stop the raw water pump 18 and stop supplying the water to be treated.
During the wastewater treatment, the blowers 14, 24, the membrane filtration pump 26, and the circulation pump 28 are kept operating.

第一の間欠曝気槽１０ａにおける曝気工程では硝化反応が行われ、第二の間欠曝気槽１０ｂにおける曝気停止工程では脱窒反応が行われる。
また、曝気工程の間は、第一の間欠曝気槽１０ａと膜分離槽２０との間で汚泥含有水を循環させる。第一の間欠曝気槽１０ａから膜分離槽２０へ移送された汚泥含有水は、膜分離槽２０の膜モジュール２２により膜濾過される。膜モジュール２２の濾過膜を透過した透過水は、透過水流路２５を通って膜分離槽２０から排出される。また、膜分離槽２０内の汚泥含有水の一部は第一の間欠曝気槽１０ａに返送される。 A nitrification reaction is performed in the aeration step in the first intermittent aeration tank 10a, and a denitrification reaction is performed in the aeration stop step in the second intermittent aeration tank 10b.
During the aeration step, the sludge-containing water is circulated between the first intermittent aeration tank 10a and the membrane separation tank 20. The sludge-containing water transferred from the first intermittent aeration tank 10a to the membrane separation tank 20 is subjected to membrane filtration by the membrane module 22 of the membrane separation tank 20. The permeated water that has passed through the filtration membrane of the membrane module 22 is discharged from the membrane separation tank 20 through the permeated water channel 25. Further, a part of the sludge-containing water in the membrane separation tank 20 is returned to the first intermittent aeration tank 10a.

このように、所定の時間が経過する度に、開閉バルブ１３ａ、１３ｂの開閉状態を切り替えて、各間欠曝気槽１０の運転を制御する。これにより、第一の間欠曝気槽１０ａと第二の間欠曝気槽１０ｂとで運転のタイミングが異なる。図２に示すタイムチャートでは、第一の間欠曝気槽１０ａにおいて曝気を行っている間は、第二の間欠曝気槽１０ｂにおいて曝気が停止され、第二の間欠曝気槽１０ｂにおいて曝気を行っている間は、第一の間欠曝気槽１０ａにおいて曝気が停止される。よって、排水処理を行っている間は２槽の間欠曝気槽１０が交互に曝気状態となり、常にどちらかの間欠曝気槽１０が曝気状態となる。   In this way, the operation of each intermittent aeration tank 10 is controlled by switching the open / close state of the open / close valves 13a, 13b every time a predetermined time elapses. Thereby, the operation timing differs between the first intermittent aeration tank 10a and the second intermittent aeration tank 10b. In the time chart shown in FIG. 2, while performing the aeration in the first intermittent aeration tank 10a, the aeration is stopped in the second intermittent aeration tank 10b, and the aeration is performed in the second intermittent aeration tank 10b. During the period, the aeration is stopped in the first intermittent aeration tank 10a. Therefore, during the drainage process, the two intermittent aeration tanks 10 are alternately in the aerated state, and one of the intermittent aerated tanks 10 is always in the aerated state.

また、所定の時間が経過する度に、開閉バルブ２７ａ、２７ｂの開閉状態を切り替えて、汚泥含有水の循環経路を入れ替える。すなわち、第一の間欠曝気槽１０ａと膜分離槽２０との間での汚泥含有水の循環と、第二の間欠曝気槽１０ｂと膜分離槽２０との間での汚泥含有水の循環とを交互に行う。また、汚泥含有水の循環は曝気状態にある間欠曝気槽１０と膜分離槽２０との間で行われるので、曝気停止状態にある間欠曝気槽１０には、高ＤＯの汚泥含有水が返送されない。よって、曝気停止状態にある間欠曝気槽１０において脱窒に必要な無酸素状態が維持されるので、効率よく窒素除去を行うことができる。   Further, each time a predetermined time elapses, the open / close state of the opening / closing valves 27a and 27b is switched, and the circulation path of the sludge-containing water is switched. That is, the circulation of the sludge-containing water between the first intermittent aeration tank 10a and the membrane separation tank 20 and the circulation of the sludge-containing water between the second intermittent aeration tank 10b and the membrane separation tank 20 Perform alternately. In addition, since the circulation of the sludge-containing water is performed between the intermittent aeration tank 10 in the aerated state and the membrane separation tank 20, the high DO sludge-containing water is not returned to the intermittent aeration tank 10 in the aeration stopped state. . Therefore, the oxygen-free state required for denitrification is maintained in the intermittent aeration tank 10 in the aeration stopped state, so that nitrogen can be efficiently removed.

第一の実施形態の排水の処理方法においては、間欠曝気槽の数をｎとし、間欠曝気工程における曝気時間をｔ１、曝気停止時間をｔ２とし、ｔ１とｔ２の最大公約数をａとしたときに、下記式（１）を満たすことが好ましい。
ｎ＝ｔ１／ａ＋ｔ２／ａ ・・・（１）
なお、ｔ１およびｔ２の単位が「時間」であり、かつ整数でない場合は、「時間」を「分」に換算して整数にした後にｔ１とｔ２の最大公約数を求め、上記式（１）に代入する。 In the method for treating wastewater of the first embodiment, when the number of intermittent aeration tanks is n, the aeration time in the intermittent aeration step is t1, the aeration stop time is t2, and the greatest common divisor of t1 and t2 is a. It is preferable that the following formula (1) is satisfied.
n = t1 / a + t2 / a (1)
If the unit of t1 and t2 is “hour” and is not an integer, the “hour” is converted to “minute” to obtain an integer, and then the greatest common divisor of t1 and t2 is obtained. Substitute for

上述したように、活性汚泥中のアンモニアおよび有機物の濃度は、曝気工程の時間の経過とともに低くなる。そのため、間欠曝気槽から膜分離槽に移送される汚泥含有水中のアンモニアおよび有機物の濃度も、曝気工程の時間の経過とともに低くなる。
膜濾過を効率よく行うためには、膜分離槽内の汚泥含有水の水質が安定していることが好ましい。膜分離槽中での汚泥含有水の水質を安定させるには、各間欠曝気槽と膜分離槽との間で行われる汚泥含有水の循環中に、各間欠曝気槽から膜分離槽に移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度を略一定にすればよい。間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たせば、各間欠曝気槽から膜分離槽に移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度を略一定にでき、膜分離槽内の汚泥含有水の水質が安定しやすい。
以下、図２〜９に示すタイムチャートを参照しながら具体的に説明する。 As described above, the concentrations of ammonia and organic substances in the activated sludge decrease with the elapse of the aeration step. Therefore, the concentrations of ammonia and organic matter in the sludge-containing water transferred from the intermittent aeration tank to the membrane separation tank also decrease with the elapse of the aeration step.
For efficient membrane filtration, it is preferable that the quality of the sludge-containing water in the membrane separation tank is stable. To stabilize the quality of the sludge-containing water in the membrane separation tank, the sludge-containing water is transferred from each intermittent aeration tank to the membrane separation tank during circulation of the sludge-containing water performed between each intermittent aeration tank and the membrane separation tank. The total concentration of ammonia and organic matter in the sludge-containing water may be substantially constant. If the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above expression (1), the sludge transferred from each intermittent aeration tank to the membrane separation tank The total concentration of ammonia and organic substances in the contained water can be made substantially constant, and the quality of the sludge-containing water in the membrane separation tank is easily stabilized.
Hereinafter, a specific description will be given with reference to time charts shown in FIGS.

図２に示すタイムチャートは、間欠曝気槽が２槽（ｎ＝２）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たす場合の、各間欠曝気槽の運転のタイミングを示している。
また、間欠曝気槽が３槽（ｎ＝３）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たす場合、各間欠曝気槽の運転のタイミングは、例えば図３に示すタイムチャートとなる。
また、間欠曝気槽が４槽（ｎ＝４）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たす場合、各間欠曝気槽の運転のタイミングは、例えば図４に示すタイムチャートとなる。 The time chart shown in FIG. 2 shows that the number of intermittent aeration tanks is two (n = 2), and the number of intermittent aeration tanks (n), the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step. The timing of operation of each intermittent aeration tank in the case where the above equation (1) is satisfied is shown.
In addition, there are three intermittent aeration tanks (n = 3), and the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above equation (1). When the condition is satisfied, the operation timing of each intermittent aeration tank is, for example, a time chart shown in FIG.
In addition, there are four intermittent aeration tanks (n = 4), and the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above equation (1). When the condition is satisfied, the operation timing of each intermittent aeration tank is, for example, a time chart shown in FIG.

間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たせば、間欠曝気槽が２槽の場合は図２に示すように、第一の間欠曝気槽が曝気状態の間中、第二の間欠曝気槽は曝気停止状態となる。また、間欠曝気槽が３槽以上の場合は、例えば図３、４に示すように、任意の間欠曝気槽が曝気状態の間中、残りの間欠曝気槽のうちのいずれか１槽が曝気状態となるように（すなわち、排水処理を行っている間は、１槽の間欠曝気槽が曝気停止状態となるように）、各間欠曝気槽の運転を制御しやすくなる。
よって、曝気状態にある間欠曝気槽と膜分離槽との間で行われる汚泥含有水の循環の開始時間と、その曝気状態にある間欠曝気槽の曝気工程の開始時間との差を「繰り下げ時間」としたときに、各間欠曝気槽において繰り下げ時間を一致させることができる。例えば図３、４において、第一の間欠曝気槽における汚泥含有水の循環の開始が、その第一の間欠曝気槽における曝気開始からα時間経過後の場合は、残りの間欠曝気槽（第二、第三、第四の間欠曝気槽）における汚泥含有水の循環の開始もその間欠曝気槽における曝気開始からα時間経過後となる。 If the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above expression (1), FIG. 2 shows the case where the number of the intermittent aeration tanks is two. As described above, while the first intermittent aeration tank is in the aeration state, the second intermittent aeration tank is in the aeration stop state. When there are three or more intermittent aeration tanks, for example, as shown in FIGS. 3 and 4, any one of the remaining intermittent aeration tanks is in the aerated state while any intermittent aeration tank is in the aerated state. (That is, one intermittent aeration tank is in the aeration stop state during the drainage treatment), so that the operation of each intermittent aeration tank can be easily controlled.
Therefore, the difference between the start time of the circulation of the sludge-containing water that is performed between the intermittent aeration tank and the membrane separation tank in the aerated state and the start time of the aeration step of the intermittent aeration tank in the aerated state is referred to as the "reduction time."", It is possible to make the deferring time coincide in each intermittent aeration tank. For example, in FIGS. 3 and 4, when the circulation of the sludge-containing water in the first intermittent aeration tank starts α hours after the start of the aeration in the first intermittent aeration tank, the remaining intermittent aeration tank (second , The third and fourth intermittent aeration tanks) start circulation of the sludge-containing water after the elapse of α hours from the start of the aeration in the intermittent aeration tanks.

各間欠曝気槽において繰り下げ時間が一致すれば、どの間欠曝気槽から膜分離槽に汚泥含有水が移送されても、汚泥含有水中のアンモニアおよび有機物のトータルの濃度が一定となりやすく（汚泥含有水の水質が同じになりやすく）、膜分離槽内の汚泥含有水の水質が安定しやすい。   If the deceleration time matches in each intermittent aeration tank, the total concentration of ammonia and organic matter in the sludge-containing water tends to be constant regardless of which intermittent aeration tank is transferred to the membrane separation tank (sludge-containing water). The water quality tends to be the same), and the quality of the sludge-containing water in the membrane separation tank is easily stabilized.

なお、図２に示すタイムチャートの場合、繰り下げ時間は「０」時間である。
図３に示すタイムチャートの場合、繰り下げ時間αは「ｔ１×１／２」時間であり、図４に示すタイムチャートの場合、繰り下げ時間αは「ｔ１×２／３」時間である。図３、４に示すタイムチャートの場合、全ての間欠曝気槽において、曝気状態にある間欠曝気槽と膜分離槽との間での汚泥含有水の循環を、曝気状態にある間欠曝気槽での曝気工程の後半で行っている。図３、４において、汚泥含有水の循環は間欠曝気槽での曝気工程の前半に行われてもよいが、上述したように活性汚泥中のアンモニアおよび有機物の濃度は、曝気工程の時間の経過とともに低くなるため、曝気工程の前半よりも後半の方が濃度は低い。よって、特に間欠曝気槽が３槽以上の場合は、汚泥含有水の循環の開始を間欠曝気槽での曝気開始から遅らせることが好ましい。 In the case of the time chart shown in FIG. 2, the deferral time is “0” time.
In the case of the time chart shown in FIG. 3, the advancement time α is “t1 × 1/2” time, and in the case of the time chart shown in FIG. 4, the advancement time α is “t1 × 2/3” time. In the case of the time charts shown in FIGS. 3 and 4, in all the intermittent aeration tanks, the circulation of the sludge-containing water between the intermittent aeration tank in the aerated state and the membrane separation tank is performed in the intermittent aeration tank in the aerated state. This is done in the latter half of the aeration process. 3 and 4, the circulation of the sludge-containing water may be performed in the first half of the aeration step in the intermittent aeration tank. However, as described above, the concentration of ammonia and organic matter in the activated sludge depends on the time of the aeration step. Therefore, the concentration is lower in the latter half of the aeration process than in the first half. Therefore, especially when there are three or more intermittent aeration tanks, it is preferable to delay the start of circulation of the sludge-containing water from the start of aeration in the intermittent aeration tank.

また、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たせば、下記条件（ｉ）〜（iii）の全てを容易に満たしやすい。
条件（ｉ）：排水を処理している間、曝気状態にある間欠曝気槽の数が一定である。
条件（ii）：排水を処理している間、曝気状態にあるいずれかの間欠曝気槽と膜分離槽との間で汚泥含有水を循環する。
条件（iii）：各間欠曝気槽において、運転条件が同じである。ここで、運転条件とは、曝気時間（ｔ１）、曝気停止時間（ｔ２）、原水流入のタイミング、汚泥含有水の循環時間、繰り下げ時間αなどである。 If the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above expression (1), all of the following conditions (i) to (iii) are satisfied. Easy to fill.
Condition (i): The number of intermittent aeration tanks in the aeration state is constant during wastewater treatment.
Condition (ii): While treating the wastewater, circulate the sludge-containing water between any of the intermittent aeration tanks in the aeration state and the membrane separation tank.
Condition (iii): The operating conditions are the same in each intermittent aeration tank. Here, the operating conditions include the aeration time (t1), the aeration stop time (t2), the timing of inflow of raw water, the circulation time of the sludge-containing water, the carry-down time α, and the like.

条件（ｉ）を満たせば、小規模なブロワを常時稼働させる運用にて排水を処理できるので、初期投資などの費用を抑えることができる。
条件（ii）を満たせば、排水を処理している間、常に膜濾過工程を実施できるので膜濾過時間が長くなる。また、透過流束を小さくすることもできる。よって、濾過膜の負荷を軽減しつつ、長期間の安定運転を実現できる。
条件（iii）を満たせば、処理水の水質を一定に保持しやすいため、排水の処理装置の処理能力や規模を小さくすることができる。 If the condition (i) is satisfied, wastewater can be treated by operating a small-sized blower at all times, so that costs such as initial investment can be reduced.
If the condition (ii) is satisfied, the membrane filtration step can be always performed while the wastewater is being treated, so that the membrane filtration time becomes longer. Also, the permeation flux can be reduced. Therefore, long-term stable operation can be realized while reducing the load on the filtration membrane.
If the condition (iii) is satisfied, the quality of the treated water can be easily maintained at a constant level, so that the treatment capacity and scale of the wastewater treatment device can be reduced.

一方、間欠曝気槽が２槽（ｎ＝２）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たさない場合、各間欠曝気槽の曝気と曝気停止のサイクルは、例えば図５に示すタイムチャートとなる。
排水処理中、膜濾過を停止しないためには、膜濾過ポンプおよび循環ポンプを常に作動させるため、汚泥含有水の循環は常に何れかの間欠曝気槽と膜分離槽との間で行われることになる。そのため、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たさない場合は、図５に示すように、各間欠曝気槽において繰り下げ時間αが異なってしまう。図５に示すタイムチャートでは、第一の間欠曝気槽と膜分離槽との間での汚泥含有水の循環の開始が、第一の間欠曝気槽での曝気工程の開始直後（すなわち、繰り下げ時間が「０」時間）であるのに対し、第二の間欠曝気槽と膜分離槽との間での汚泥含有水の循環の開始が、第二の間欠曝気槽での曝気工程の途中である（繰り下げ時間αが生じている。）。そのため、第一の間欠曝気槽から膜分離槽に移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度は、第二の間欠曝気槽から膜分離槽に移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度に比べて高くなり、膜分離槽内の汚泥含有水の水質が安定しにくい。 On the other hand, there are two intermittent aeration tanks (n = 2), and the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above equation (1). If not, the cycle of the aeration of each intermittent aeration tank and the stop of the aeration are, for example, a time chart shown in FIG.
In order not to stop the membrane filtration during the wastewater treatment, the circulation of the sludge-containing water is always performed between any intermittent aeration tank and the membrane separation tank in order to always operate the membrane filtration pump and the circulation pump. Become. Therefore, when the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step do not satisfy the above expression (1), as shown in FIG. In the aeration tank, the delay time α differs. In the time chart shown in FIG. 5, the start of the circulation of the sludge-containing water between the first intermittent aeration tank and the membrane separation tank is immediately after the start of the aeration step in the first intermittent aeration tank (that is, Is "0" hour), whereas the start of circulation of the sludge-containing water between the second intermittent aeration tank and the membrane separation tank is in the middle of the aeration step in the second intermittent aeration tank. (A downtime α has occurred.) Therefore, the total concentration of ammonia and organic matter in the sludge-containing water transferred from the first intermittent aeration tank to the membrane separation tank depends on the ammonia and organic matter in the sludge-containing water transferred from the second intermittent aeration tank to the membrane separation tank. And the quality of the sludge-containing water in the membrane separation tank is not easily stabilized.

間欠曝気槽が３槽（ｎ＝３）である場合も同様であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たさないと、例えば図６に示すように、各間欠曝気槽において繰り下げ時間αが異なってしまう。そのため、各間欠曝気槽から膜分離槽へ移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度が異なり、膜分離槽内の汚泥含有水の水質が安定しにくい。   The same applies to the case where the number of the intermittent aeration tanks is three (n = 3). If 1) is not satisfied, for example, as shown in FIG. 6, the intermittent aeration tanks have different deferring times α. Therefore, the total concentration of ammonia and organic substances in the sludge-containing water transferred from each intermittent aeration tank to the membrane separation tank is different, and the quality of the sludge-containing water in the membrane separation tank is not easily stabilized.

また、例えば図７〜９に示すように、各間欠曝気槽において繰り下げ時間αが同じであっても、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たさない場合は、上記条件（ｉ）〜（iii）の少なくとも１つを満たさない。   Also, for example, as shown in FIGS. 7 to 9, even if the decrement time α is the same in each intermittent aeration tank, the number of intermittent aeration tanks (n), the aeration time (t1) and the aeration stop time in the intermittent aeration step When (t2) does not satisfy the above expression (1), at least one of the above conditions (i) to (iii) is not satisfied.

図７に示すタイムチャートの場合、間欠曝気槽が２槽（ｎ＝２）であり、各間欠曝気槽の繰り下げ時間αは「ｔ１×１／４」時間である。しかし、第一の間欠曝気槽と第二の間欠曝気槽とが同時に曝気状態となる時間帯が生じるため、曝気状態にある間欠曝気槽の数が一定ではなく、条件（ｉ）を満たさない。例えば図２に示す場合は条件（ｉ）を満たすため、１槽の間欠曝気槽を曝気できるだけの処理能力を有するブロワを用いることができるが、図７の場合は２槽の間欠曝気槽を同時に曝気させる処理能力を有するブロワを使用する必要があるため、初期投資などの費用がかかってしまう。   In the case of the time chart shown in FIG. 7, the number of intermittent aeration tanks is two (n = 2), and the deferred time α of each intermittent aeration tank is “t1 × １ ／”. However, since a time zone occurs in which the first intermittent aeration tank and the second intermittent aeration tank are simultaneously in the aeration state, the number of intermittent aeration tanks in the aeration state is not constant and does not satisfy the condition (i). For example, in the case shown in FIG. 2, to satisfy the condition (i), a blower having a processing capacity capable of aerating one intermittent aeration tank can be used. In the case of FIG. 7, however, the two intermittent aeration tanks are simultaneously used. Since it is necessary to use a blower having a processing capacity for aeration, costs such as initial investment are required.

図８に示すタイムチャートの場合、間欠曝気槽が３槽（ｎ＝３）であり、各間欠曝気槽の繰り下げ時間αは「ｔ１×１／２」時間である。しかし、この場合も曝気状態にある間欠曝気槽の数が一定ではないため、条件（ｉ）を満たさない。加えて、汚泥含有水の循環が行われない時間帯が生じるため、条件（ii）も満たさない。汚泥含有水の循環が行われない間は処理水の吸引ができないため、膜濾過時間が制限され、透過流束が大きくなり、濾過膜が閉塞することがある。   In the case of the time chart shown in FIG. 8, there are three intermittent aeration tanks (n = 3), and the decrementing time α of each intermittent aeration tank is “t1 ××” time. However, also in this case, the number of intermittent aeration tanks in the aeration state is not constant, and thus does not satisfy the condition (i). In addition, the time period during which the sludge-containing water is not circulated occurs, so that the condition (ii) is not satisfied. Since the treated water cannot be sucked while the sludge-containing water is not circulated, the membrane filtration time is limited, the permeation flux increases, and the filtration membrane may be blocked.

図９に示すタイムチャートの場合、間欠曝気槽が２槽（ｎ＝２）であり、各間欠曝気槽の繰り下げ時間αは「０」時間である。また、この場合は条件（ｉ）、（ii）を満たすものの、第一の間欠曝気槽と第二の間欠曝気槽とで曝気時間（ｔ１）および曝気停止時間（ｔ２）が異なり、条件（iii）を満たさない。よって、処理水の水質を一定に保持しにくい。   In the case of the time chart shown in FIG. 9, there are two intermittent aeration tanks (n = 2), and the decrement time α of each intermittent aeration tank is “0” time. In this case, although the conditions (i) and (ii) are satisfied, the aeration time (t1) and the aeration stop time (t2) are different between the first intermittent aeration tank and the second intermittent aeration tank, and the condition (iii) ) Is not satisfied. Therefore, it is difficult to keep the quality of the treated water constant.

なお、図２〜９に示すタイムチャートでは、全ての間欠曝気槽の運転のタイミングが異なるように、各間欠曝気槽の運転が制御されているが、間欠曝気槽が３槽以上の場合、排水処理を行っている間は１槽以上の間欠曝気槽が曝気状態となっていれば、複数の間欠曝気槽の運転のタイミングが同じであってもよい。ただし、ブロアの処理能力を考慮すると、全ての間欠曝気槽の運転のタイミングが異なるように、各間欠曝気槽の運転を制御することが好ましい。
さらに、ブロアの処理能力を考慮した場合、排水処理を行っている間、１槽以上の間欠曝気槽が曝気停止状態となるように、各間欠曝気槽の運転を制御することが好ましく、１槽の間欠曝気槽が曝気停止状態となるように、各間欠曝気槽の運転を制御することがより好ましい。 In the time charts shown in FIGS. 2 to 9, the operation of each intermittent aeration tank is controlled so that the operation timings of all the intermittent aeration tanks are different. The operation timing of the plurality of intermittent aeration tanks may be the same as long as one or more intermittent aeration tanks are in the aerated state during the processing. However, considering the processing capacity of the blower, it is preferable to control the operation of each intermittent aeration tank so that the operation timing of all the intermittent aeration tanks is different.
Further, in consideration of the processing capacity of the blower, it is preferable to control the operation of each intermittent aeration tank so that one or more intermittent aeration tanks are in an aeration stop state during the drainage treatment. It is more preferable to control the operation of each intermittent aeration tank so that the intermittent aeration tank is in an aeration stopped state.

また、図２〜８に示すタイムチャートでは、間欠曝気工程における曝気時間（ｔ１）が曝気停止時間（ｔ２）と同じ場合または長い場合を想定したものであるが、曝気停止時間（ｔ２）が曝気時間（ｔ１）よりも長い場合であっても、上記式（１）を満たせば、膜分離槽内の汚泥含有水の水質を安定化させやすい。   In the time charts shown in FIGS. 2 to 8, it is assumed that the aeration time (t1) in the intermittent aeration step is equal to or longer than the aeration stop time (t2). Even when the time is longer than the time (t1), if the above expression (1) is satisfied, the quality of the sludge-containing water in the membrane separation tank can be easily stabilized.

間欠曝気槽が３槽（ｎ＝３）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たし、かつｔ１＜ｔ２の場合、各間欠曝気槽の曝気と曝気停止のサイクルは、例えば図１０に示すタイムチャートとなる。
また、間欠曝気槽が５槽（ｎ＝５）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たし、かつｔ１＜ｔ２の場合、各間欠曝気槽の曝気と曝気停止のサイクルは、例えば図１１に示すタイムチャートとなる。
図１０、１１に示すように、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たし、かつｔ１＜ｔ２の場合でも、各間欠曝気槽において繰り下げ時間を一致させやすくできる。よって、どの間欠曝気槽から膜分離槽に汚泥含有水が移送されても、汚泥含有水中のアンモニアおよび有機物のトータルの濃度が一定となりやすく、膜分離槽内の汚泥含有水の水質が安定しやすい。
図１０に示すタイムチャートの場合、繰り下げ時間は「０」時間である。図１１に示すタイムチャートの場合、繰り下げ時間は「ｔ１×１／２」時間である。 There are three intermittent aeration tanks (n = 3), and the number (n) of the intermittent aeration tanks, the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above formula (1), In the case of t1 <t2, the cycle of the aeration of each intermittent aeration tank and the stop of the aeration are, for example, a time chart shown in FIG.
In addition, there are five intermittent aeration tanks (n = 5), and the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above equation (1). When t1 <t2 is satisfied, the cycle of the aeration of each intermittent aeration tank and the stop of the aeration are, for example, a time chart shown in FIG.
As shown in FIGS. 10 and 11, the number (n) of the intermittent aeration tanks, the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above expression (1), and satisfy t1 <t2. Even in this case, it is possible to easily match the deferring time in each intermittent aeration tank. Therefore, no matter which intermittent aeration tank transfers the sludge-containing water to the membrane separation tank, the total concentration of ammonia and organic substances in the sludge-containing water tends to be constant, and the quality of the sludge-containing water in the membrane separation tank is easily stabilized. .
In the case of the time chart shown in FIG. 10, the deferral time is “0” time. In the case of the time chart shown in FIG. 11, the deferral time is “t1 × １ ／” time.

＜第二の実施形態＞
本発明の第二の実施形態の排水の処理方法は、第一の実施形態と同様、被処理水を間欠曝気槽１０に導き、曝気と曝気停止とを繰り返して、活性汚泥により生物処理する間欠曝気工程と、間欠曝気槽１０内の生物処理水と活性汚泥とからなる汚泥含有水を膜分離槽２０に移送して膜濾過する膜濾過工程と、膜分離槽２０から間欠曝気槽１０に、膜分離槽２０内の汚泥含有水の一部を返送させる返送工程とを有する、間欠曝気膜分離活性汚泥法により排水を処理する方法である。 <Second embodiment>
Similar to the first embodiment, the wastewater treatment method of the second embodiment of the present invention guides the water to be treated to the intermittent aeration tank 10, repeats aeration and aeration stop, and performs biological treatment with activated sludge. Aeration step, a membrane filtration step of transferring sludge-containing water composed of biologically treated water and activated sludge in the intermittent aeration tank 10 to the membrane separation tank 20 and membrane filtration, and from the membrane separation tank 20 to the intermittent aeration tank 10, And a return step of returning a part of the sludge-containing water in the membrane separation tank 20, wherein the wastewater is treated by an intermittent aeration membrane separation activated sludge method.

第二の実施形態の排水の処理方法においては、間欠曝気槽の数をｎとし、間欠曝気工程における曝気時間をｔ１、曝気停止時間をｔ２としたときに、下記式（２）を満たすことが好ましい。
ｔ１／ｔ２＝ｎ−１ ・・・（２） In the wastewater treatment method according to the second embodiment, when the number of intermittent aeration tanks is n, the aeration time in the intermittent aeration step is t1, and the aeration stop time is t2, the following formula (2) is satisfied. preferable.
t1 / t2 = n-1 (2)

上述したように、膜濾過を効率よく行うためには、膜分離槽内の汚泥含有水の水質が安定していることが好ましい。膜分離槽中での汚泥含有水の水質を安定させるには、各間欠曝気槽と膜分離槽との間で行われる汚泥含有水の循環中に、各間欠曝気槽から膜分離槽に移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度を略一定にすればよい。間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（２）を満たす場合も、各間欠曝気槽から膜分離槽に移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度を略一定にでき、膜分離槽内の汚泥含有水の水質が安定しやすい。   As described above, in order to efficiently perform membrane filtration, it is preferable that the quality of the sludge-containing water in the membrane separation tank is stable. To stabilize the quality of the sludge-containing water in the membrane separation tank, the sludge-containing water is transferred from each intermittent aeration tank to the membrane separation tank during circulation of the sludge-containing water performed between each intermittent aeration tank and the membrane separation tank. The total concentration of ammonia and organic matter in the sludge-containing water may be substantially constant. Even when the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above-mentioned formula (2), they are transferred from each intermittent aeration tank to the membrane separation tank. The total concentration of ammonia and organic substances in the sludge-containing water can be made substantially constant, and the quality of the sludge-containing water in the membrane separation tank is easily stabilized.

間欠曝気槽が２槽（ｎ＝２）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（２）を満たす場合、各間欠曝気槽の運転のタイミングは、例えば図２に示すタイムチャートとなる。
間欠曝気槽が３槽（ｎ＝３）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（２）を満たす場合、各間欠曝気槽の運転のタイミングは、例えば図３に示すタイムチャートとなる。
間欠曝気槽が４槽（ｎ＝４）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（２）を満たす場合、各間欠曝気槽の運転のタイミングは、例えば図４に示すタイムチャートとなる。 When there are two intermittent aeration tanks (n = 2) and the number (n) of the intermittent aeration tanks, the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above equation (2). The operation timing of each intermittent aeration tank is, for example, a time chart shown in FIG.
When there are three intermittent aeration tanks (n = 3), and the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above equation (2). The operation timing of each intermittent aeration tank is, for example, a time chart shown in FIG.
When there are four intermittent aeration tanks (n = 4), and the number (n) of the intermittent aeration tanks, the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above equation (2). The operation timing of each intermittent aeration tank is, for example, a time chart shown in FIG.

一方、間欠曝気槽が２槽（ｎ＝２）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（２）を満たさない場合、各間欠曝気槽の曝気と曝気停止のサイクルは、例えば図５に示すタイムチャートとなる。
間欠曝気槽が３槽（ｎ＝３）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（２）を満たさない場合、各間欠曝気槽の曝気と曝気停止のサイクルは、例えば図６に示すタイムチャートとなる。
なお、図２〜６に示すタイムチャートは第一の実施形態と同じであるため、その説明を省略する。 On the other hand, there are two intermittent aeration tanks (n = 2), and the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above equation (2). If not, the cycle of the aeration of each intermittent aeration tank and the stop of the aeration are, for example, a time chart shown in FIG.
There are three intermittent aeration tanks (n = 3), and the number (n) of the intermittent aeration tanks, the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step do not satisfy the above equation (2). In this case, the cycle of the aeration of each intermittent aeration tank and the stop of the aeration is, for example, a time chart shown in FIG.
Note that the time charts shown in FIGS. 2 to 6 are the same as those in the first embodiment, and a description thereof will be omitted.

上記式（２）は、間欠曝気工程における曝気時間（ｔ１）が曝気停止時間（ｔ２）と同じ場合または長い場合を想定したものであるが、曝気停止時間（ｔ２）が曝気時間（ｔ１）と同じ場合または長い場合であっても、下記式（３）を満たせば、膜分離槽内の汚泥含有水の水質を安定化させやすい。
ｔ２／ｔ１＝ｎ−１ ・・・（３） The above equation (2) is based on the assumption that the aeration time (t1) in the intermittent aeration step is equal to or longer than the aeration stop time (t2), but the aeration stop time (t2) is equal to the aeration time (t1). Even if the length is the same or the length is longer, if the following expression (3) is satisfied, the quality of the sludge-containing water in the membrane separation tank can be easily stabilized.
t2 / t1 = n-1 (3)

間欠曝気槽が３槽（ｎ＝３）であり、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（３）を満たす場合、各間欠曝気槽の曝気と曝気停止のサイクルは、例えば図１０に示すタイムチャートとなる。
なお、図１０に示すタイムチャートは第一の実施形態と同じであるため、その説明を省略する。 When there are three intermittent aeration tanks (n = 3) and the number (n) of the intermittent aeration tanks, the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above equation (3). The cycle of the aeration of each intermittent aeration tank and the stop of the aeration is, for example, a time chart shown in FIG.
Note that the time chart shown in FIG. 10 is the same as in the first embodiment, and a description thereof will be omitted.

第二の実施形態の排水の処理方法においても、間欠曝気槽が３槽以上の場合、排水処理を行っている間は１槽以上の間欠曝気槽が曝気状態となっていれば、複数の間欠曝気槽の運転のタイミングが同じであってもよい。ただし、ブロアの処理能力を考慮すると、全ての間欠曝気槽の運転のタイミングが異なるように、各間欠曝気槽の運転を制御することが好ましい。
さらに、ブロアの処理能力を考慮した場合、排水処理を行っている間、１槽以上の間欠曝気槽が曝気停止状態となるように、各間欠曝気槽の運転を制御することが好ましく、１槽の間欠曝気槽が曝気停止状態となるように、各間欠曝気槽の運転を制御することがより好ましい。 Also in the wastewater treatment method of the second embodiment, when the number of intermittent aeration tanks is three or more, if one or more intermittent aeration tanks are in the aerated state during drainage treatment, a plurality of intermittent aeration tanks are provided. The operation timing of the aeration tank may be the same. However, considering the processing capacity of the blower, it is preferable to control the operation of each intermittent aeration tank so that the operation timing of all the intermittent aeration tanks is different.
Further, in consideration of the processing capacity of the blower, it is preferable to control the operation of each intermittent aeration tank so that one or more intermittent aeration tanks are in an aeration stop state during the drainage treatment. It is more preferable to control the operation of each intermittent aeration tank so that the intermittent aeration tank is in an aeration stopped state.

「作用効果」
以上説明した本発明の排水の処理方法および排水の処理装置では、間欠曝気槽を複数用い、排水処理を行っている間は１槽以上の間欠曝気槽が曝気状態となるように、各間欠曝気槽の運転を制御する。加えて、汚泥含有水の循環を曝気状態にある間欠曝気槽と膜分離槽との間で行う。よって、排水処理を行っている間、膜濾過を連続して実施しても曝気停止状態の間欠曝気槽には高ＤＯの汚泥含有水が返送されない。そのため、曝気停止状態の間欠曝気槽内を脱窒に必要な無酸素状態またはリン除去に必要な嫌気状態として維持できるので、安定した窒素処理またはリン処理が可能となる。加えて、排水処理を行っている間は膜濾過を停止することなく連続して実施することができるため、排水の処理効率（１日当たりの処理水量）を高くできる。また、本発明であれば排水の処理効率が高いので、濾過膜の膜面積を必要以上に大きくしなくて済む。また、フラックス（透過流束）を低くすることもできる。 "Effects"
In the wastewater treatment method and wastewater treatment apparatus of the present invention described above, a plurality of intermittent aeration tanks are used, and each of the intermittent aeration tanks is set so that one or more intermittent aeration tanks are in an aerated state during wastewater treatment. Control the operation of the tank. In addition, the circulation of the sludge-containing water is performed between the intermittent aeration tank in the aerated state and the membrane separation tank. Therefore, even if the membrane filtration is continuously performed during the wastewater treatment, the high DO-containing sludge-containing water is not returned to the intermittent aeration tank in the aeration stopped state. Therefore, since the inside of the intermittent aeration tank in the aeration stopped state can be maintained in an anoxic state required for denitrification or an anaerobic state required for phosphorus removal, stable nitrogen treatment or phosphorus treatment can be performed. In addition, since the membrane filtration can be performed continuously without stopping during the wastewater treatment, the wastewater treatment efficiency (the amount of treated water per day) can be increased. In addition, according to the present invention, since the treatment efficiency of wastewater is high, it is not necessary to increase the membrane area of the filtration membrane more than necessary. Also, the flux (permeation flux) can be reduced.

また、排水処理を行っている間、１槽以上の間欠曝気槽が曝気停止状態であれば、全ての間欠曝気槽が曝気状態となるタイミングがある場合に比べて、間欠曝気槽を曝気する際に用いるブロアとして処理能力の小さいブロアを用いることができる。これは、排水処理を行っている間、全ての間欠曝気槽が曝気状態となるタイミングがあると、全ての間欠曝気槽を曝気できるだけの処理能力を有するブロアを用いる必要があるためである。
間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）〜（３）のいずれかを満たせば、排水処理を行っている間、１槽以上の間欠曝気槽が曝気停止状態となるように、各間欠曝気槽の運転を制御しやすい。例えば、２槽の間欠曝気槽を用いて曝気を交互に行えば、排水処理を行っている間、曝気状態にある間欠曝気槽は常に１槽である。そのため、間欠曝気槽の数が１槽から２槽に増えても（倍になっても）、１槽分の間欠曝気槽を曝気するだけの処理能力を有するブロアを用いればよいので、経済的である。特に、間欠曝気槽の数（ｎ）と、間欠曝気工程における曝気時間（ｔ１）および曝気停止時間（ｔ２）とが上記式（１）を満たせば、上記条件（ｉ）〜（iii）の全てを容易に満たしやすい。よって、初期投資などの費用を抑えることができる、濾過膜の負荷を軽減しつつ長期間の安定運転を実現できる、処理水の水質を一定に保持しやすい、などの効果も得られやすい。 Also, during the drainage process, if one or more intermittent aeration tanks are in the aeration-stop state, the intermittent aeration tank may be aerated when compared to the case where all intermittent aeration tanks are in the aeration state. Can be used as a blower having a small processing capacity. This is because if there is a timing at which all the intermittent aeration tanks are in the aerated state during the drainage treatment, it is necessary to use a blower having a processing capacity capable of aerating all the intermittent aeration tanks.
If the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy any of the above formulas (1) to (3), the drainage treatment is performed. During operation, it is easy to control the operation of each intermittent aeration tank so that one or more intermittent aeration tanks are in an aeration stopped state. For example, if aeration is alternately performed using two intermittent aeration tanks, the number of intermittent aeration tanks in the aeration state is always one during drainage treatment. Therefore, even if the number of intermittent aeration tanks is increased from one tank to two tanks (even if the number of tanks is doubled), a blower having a processing capacity enough to aerate one intermittent aeration tank may be used. It is. In particular, if the number (n) of the intermittent aeration tanks and the aeration time (t1) and the aeration stop time (t2) in the intermittent aeration step satisfy the above expression (1), all of the above conditions (i) to (iii) are satisfied. Easy to fill. Therefore, it is easy to obtain the effects of reducing costs such as initial investment, realizing stable operation for a long time while reducing the load on the filtration membrane, and easily maintaining the quality of the treated water constant.

以下、実施例によって本発明を詳細に説明するが、本発明は以下の記載によっては限定されない。   Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited by the following description.

［実施例１］
図１に示す排水の処理装置１を用い、以下のようにして排水の処理を行った。
排水としては、養豚畜舎から排出された、窒素含有排水を用いた。
第一の間欠曝気槽１０ａおよび第二の間欠曝気槽１０ｂとしては、容積が１０ｍ３のものを用いた。また、膜モジュール２２としては、中空糸膜モジュールを用いた。中空糸膜としては、膜面積が２０ｍ２のものを用いた。 [Example 1]
Using the wastewater treatment apparatus 1 shown in FIG. 1, wastewater treatment was performed as follows.
As the wastewater, nitrogen-containing wastewater discharged from a pig farm was used.
As the first intermittent aeration tank 10a and the second intermittent aeration tank 10b, those having a volume of 10 m 3 were used. As the membrane module 22, a hollow fiber membrane module was used. A hollow fiber membrane having a membrane area of 20 m 2 was used.

各間欠曝気槽１０において、曝気時間（ｔ１）を４時間、曝気停止時間（ｔ２）を４時間とし、図２に示すタイムチャートとなるように（すなわち、第一の間欠曝気槽１０ａで曝気を行っている間は、第二の間欠曝気槽１０ｂでは曝気が停止されるように）、各間欠曝気槽１０の運転を制御し、第一の間欠曝気槽１０ａと第二の間欠曝気槽１０ｂとで膜濾過（汚泥含有水の循環）を交互に行った。
なお、間欠曝気槽１０全体に対する１日当たりの原水投入量が１０ｍ３となるようにした。
また、１回の曝気と曝気停止を１サイクルとすると、上記条件の場合、１日のサイクル数が３回となり、１サイクルにおける各間欠曝気槽への原水投入量は、１．６７ｍ３（＝１０ｍ３／ｄ÷３回÷２槽）となる。
また、ｔ１とｔ２の最大公約数（ａ）は４であることから、ｔ１／ａ＋ｔ２／ａ＝２であり、上記式（１）を満たしていた。
さらに、ｔ１／ｔ２＝１であり、上記式（２）も満たしていた。 In each intermittent aeration tank 10, the aeration time (t1) is set to 4 hours, and the aeration stop time (t2) is set to 4 hours, as shown in the time chart of FIG. 2 (that is, the aeration is performed in the first intermittent aeration tank 10a). During the operation, the aeration is stopped in the second intermittent aeration tank 10b), the operation of each intermittent aeration tank 10 is controlled, and the first intermittent aeration tank 10a and the second intermittent aeration tank 10b are To alternately perform membrane filtration (circulation of sludge-containing water).
The amount of raw water input per day for the entire intermittent aeration tank 10 was set to 10 m 3 .
Further, assuming that one cycle of aeration and stop of aeration is one cycle under the above conditions, the number of cycles per day is three times, and the input amount of raw water to each intermittent aeration tank in one cycle is 1.67 m 3 (= 10 m 3 / d {3 times 2 tanks).
Since the greatest common divisor (a) of t1 and t2 is 4, t1 / a + t2 / a = 2, which satisfies the expression (1).
Furthermore, t1 / t2 = 1, which also satisfied the above expression (2).

実施例１の場合、１日当たりの膜濾過時間は２４時間であり、連続して膜濾過を実施できた。また、曝気停止状態の間欠曝気槽には汚泥含有水が返送されないので、曝気停止状態の間欠曝気槽内を無酸素状態に維持でき、安定した窒素処理を行うことができた。
また、中空糸膜の膜面積が２０ｍ２であることから、１０ｍ３／ｄの処理水を得るための平均膜濾過フラックスは０．５ｍ／ｄ（＝１０ｍ３／ｄ÷２０ｍ２）であり、安定した膜濾過の継続が可能であった。
また、実施例１の場合、第一の間欠曝気槽と第二の間欠曝気槽とが同時に曝気される時間帯が生じない（すなわち、上記条件（ｉ）を満たす）。よって、間欠曝気槽は２槽であるが、１槽分の間欠曝気槽を曝気するだけの処理能力を有するブロアで全ての間欠曝気槽を曝気処理でき、初期コストを削減できた。
また、実施例１の場合、上記条件（ii）、（iii）も満たしていた。 In the case of Example 1, the membrane filtration time per day was 24 hours, and the membrane filtration could be continuously performed. Further, since the sludge-containing water is not returned to the intermittent aeration tank in the aeration stopped state, the inside of the intermittent aeration tank in the aeration stopped state can be maintained in an oxygen-free state, and a stable nitrogen treatment can be performed.
Further, since the membrane area of the hollow fiber membrane is 20 m 2 , the average membrane filtration flux for obtaining treated water of 10 m 3 / d is 0.5 m / d (= 10 m 3 / d ÷ 20 m 2 ), It was possible to continue stable membrane filtration.
Further, in the case of the first embodiment, there is no time zone in which the first intermittent aeration tank and the second intermittent aeration tank are simultaneously aerated (that is, the condition (i) is satisfied). Therefore, although the number of the intermittent aeration tanks is two, all the intermittent aeration tanks can be aerated with a blower having a processing capacity enough to aerate one of the intermittent aeration tanks, thereby reducing the initial cost.
In the case of Example 1, the above conditions (ii) and (iii) were also satisfied.

［実施例２］
間欠曝気槽を３槽とし、各間欠曝気槽の容積を６．７ｍ３に変更し、かつ各間欠曝気槽において、曝気時間（ｔ１）を４時間、曝気停止時間（ｔ２）を２時間とし、図３に示すタイムチャートとなるように、各間欠曝気槽の運転を制御し、かつ汚泥含有水の循環の開始のタイミング（繰り下げ時間α）を設定した以外は、実施例１と同様にして排水の処理を行った。
なお、実施例２の場合、１日のサイクル数が４回となり、１サイクルにおける各間欠曝気槽への原水投入量は、０．８３ｍ３（＝１０ｍ３／ｄ÷４回÷３槽）となる。
また、ｔ１とｔ２の最大公約数（ａ）は２であることから、ｔ１／ａ＋ｔ２／ａ＝３であり、上記式（１）を満たしていた。
さらに、ｔ１／ｔ２＝２であり、上記式（２）も満たしていた。 [Example 2]
Three intermittent aeration tanks, the volume of each intermittent aeration tank was changed to 6.7 m 3 , and in each intermittent aeration tank, the aeration time (t1) was 4 hours, the aeration stop time (t2) was 2 hours, As shown in the time chart of FIG. 3, drainage was performed in the same manner as in Example 1 except that the operation of each intermittent aeration tank was controlled, and the timing of the start of circulation of the sludge-containing water (delaying time α) was set. Was performed.
In the case of Example 2, the number of cycles per day is four, and the amount of raw water charged to each intermittent aeration tank in one cycle is 0.83 m 3 (= 10 m 3 / d ÷ 4 times ÷ 3 tanks). Become.
Further, since the greatest common divisor (a) of t1 and t2 is 2, t1 / a + t2 / a = 3, which satisfies the above expression (1).
Furthermore, t1 / t2 = 2, which also satisfied the above expression (2).

実施例２の場合、１日当たりの膜濾過時間は２４時間であり、連続して膜濾過を実施できた。また、曝気停止状態の間欠曝気槽には汚泥含有水が返送されないので、曝気停止状態の間欠曝気槽内を無酸素状態に維持でき、安定した窒素処理を行うことができた。
また、中空糸膜の膜面積が２０ｍ２であることから、１０ｍ３／ｄの処理水を得るための平均膜濾過フラックスは０．５ｍ／ｄ（＝１０ｍ３／ｄ÷２０ｍ２）であり、安定した膜濾過の継続が可能であった。
また、実施例２の場合、２槽の間欠曝気槽が同時に曝気される時間帯は生じるものの、全ての間欠曝気槽が同時に曝気される時間帯は生じず、曝気状態にある間欠曝気槽の数が常に一定である（すなわち、上記条件（ｉ）を満たす）。よって、間欠曝気槽は３槽であるが、２槽分の間欠曝気槽を曝気するだけの処理能力を有するブロアで全ての間欠曝気槽を曝気処理でき、初期コストを削減できた。
また、実施例２の場合、上記条件（ii）、（iii）も満たしていた。 In the case of Example 2, the membrane filtration time per day was 24 hours, and the membrane filtration could be continuously performed. Further, since the sludge-containing water is not returned to the intermittent aeration tank in the aeration stopped state, the inside of the intermittent aeration tank in the aeration stopped state can be maintained in an oxygen-free state, and a stable nitrogen treatment can be performed.
Further, since the membrane area of the hollow fiber membrane is 20 m 2 , the average membrane filtration flux for obtaining treated water of 10 m 3 / d is 0.5 m / d (= 10 m 3 / d ÷ 20 m 2 ), It was possible to continue stable membrane filtration.
Further, in the case of Example 2, although the time period during which the two intermittent aeration tanks are simultaneously aerated occurs, the time period during which all the intermittent aeration tanks are simultaneously aerated does not occur, and the number of intermittent aeration tanks in the aerated state Is always constant (that is, the condition (i) is satisfied). Therefore, although the number of the intermittent aeration tanks is three, all the intermittent aeration tanks can be aerated with a blower having a processing capacity enough to aerate the two intermittent aeration tanks, thereby reducing the initial cost.
In the case of Example 2, the above conditions (ii) and (iii) were also satisfied.

［実施例３］
各間欠曝気槽において、曝気時間（ｔ１）を４時間、曝気停止時間（ｔ２）を２時間とし、図５に示すタイムチャートとなるように、各間欠曝気槽の運転を制御し、かつ汚泥含有水の循環の開始のタイミング（繰り下げ時間α）を設定した以外は、実施例１と同様にして排水の処理を行った。
なお、実施例３の場合、１日のサイクル数が４回となり、１サイクルにおける各間欠曝気槽への原水投入量は、１．２５ｍ３（＝１０ｍ３／ｄ÷４回÷２槽）となる。
また、ｔ１とｔ２の最大公約数（ａ）は２であることから、ｔ１／ａ＋ｔ２／ａ＝３であり、上記式（１）を満たさなかった。
さらに、ｔ１／ｔ２＝２であり、上記式（２）も満たさなかった。 [Example 3]
In each intermittent aeration tank, the aeration time (t1) is 4 hours, the aeration stop time (t2) is 2 hours, and the operation of each intermittent aeration tank is controlled as shown in the time chart of FIG. Drainage treatment was performed in the same manner as in Example 1 except that the timing of starting the circulation of water (the delay time α) was set.
In the case of Example 3, the number of cycles per day is four, and the input amount of raw water to each intermittent aeration tank in one cycle is 1.25 m 3 (= 10 m 3 / d ÷ 4 times ÷ 2 tanks). Become.
Further, since the greatest common divisor (a) of t1 and t2 is 2, t1 / a + t2 / a = 3, which did not satisfy the above equation (1).
Furthermore, t1 / t2 = 2, and the above-mentioned expression (2) was not satisfied.

実施例３の場合、１日当たりの膜濾過時間は２４時間であり、連続して膜濾過を実施できた。また、曝気停止状態の間欠曝気槽には汚泥含有水が返送されないので、曝気停止状態の間欠曝気槽内を無酸素状態に維持でき、安定した窒素処理を行うことができた。
また、中空糸膜の膜面積が２０ｍ２であることから、１０ｍ３／ｄの処理水を得るための平均膜濾過フラックスは０．５ｍ／ｄ（＝１０ｍ３／ｄ÷２０ｍ２）であり、安定した膜濾過の継続が可能であった。 In the case of Example 3, the membrane filtration time per day was 24 hours, and the membrane filtration could be performed continuously. Further, since the sludge-containing water is not returned to the intermittent aeration tank in the aeration stopped state, the inside of the intermittent aeration tank in the aeration stopped state can be maintained in an oxygen-free state, and a stable nitrogen treatment can be performed.
Further, since the membrane area of the hollow fiber membrane is 20 m 2 , the average membrane filtration flux for obtaining treated water of 10 m 3 / d is 0.5 m / d (= 10 m 3 / d ÷ 20 m 2 ), It was possible to continue stable membrane filtration.

しかし、図５に示すように、実施例３の場合、各間欠曝気槽における繰り下げ時間αが異なる。具体的には、第一の間欠曝気槽と膜分離槽との間での汚泥含有水の循環の開始は第一の間欠曝気槽での曝気工程の開始直後であり、第二の間欠曝気槽と膜分離槽との間での汚泥含有水の循環の開始は第二の間欠曝気槽での曝気工程の途中である。そのため、第一の間欠曝気槽から膜分離槽に移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度は、第二の間欠曝気槽から膜分離槽に移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度に比べて高くなり、実施例１、２に比べて膜分離槽内の汚泥含有水の水質が安定しにくかった。
また、実施例３の場合、第一の間欠曝気槽と第二の間欠曝気槽とが同時に曝気される時間帯が生じた（すなわち、上記条件（ｉ）を満たさない）。よって、実施例１の場合と間欠曝気槽の数は同じであるが、実施例３では２槽分の間欠曝気槽を曝気するだけの処理能力を有するブロアが必要であり、実施例１に比べて初期コストが増加した。
また、実施例３の場合、上記条件（iii）も満たさなかった。 However, as shown in FIG. 5, in the case of the third embodiment, the deferring time α in each intermittent aeration tank is different. Specifically, the start of the circulation of the sludge-containing water between the first intermittent aeration tank and the membrane separation tank is immediately after the start of the aeration step in the first intermittent aeration tank, and the second intermittent aeration tank The start of the circulation of the sludge-containing water between the membrane and the membrane separation tank is in the middle of the aeration step in the second intermittent aeration tank. Therefore, the total concentration of ammonia and organic matter in the sludge-containing water transferred from the first intermittent aeration tank to the membrane separation tank depends on the ammonia and organic matter in the sludge-containing water transferred from the second intermittent aeration tank to the membrane separation tank. , And the quality of the sludge-containing water in the membrane separation tank was less stable than in Examples 1 and 2.
Further, in the case of Example 3, there was a time zone in which the first intermittent aeration tank and the second intermittent aeration tank were simultaneously aerated (that is, the condition (i) was not satisfied). Therefore, the number of intermittent aeration tanks is the same as in the case of the first embodiment. However, in the third embodiment, a blower having a processing capacity enough to aerate two intermittent aeration tanks is required. Increased initial costs.
In the case of Example 3, the above condition (iii) was not satisfied.

［実施例４］
間欠曝気槽を３槽とし、各間欠曝気槽の容積を６．７ｍ３に変更し、かつ各間欠曝気槽において、曝気時間（ｔ１）を６時間、曝気停止時間（ｔ２）を２時間とし、図６に示すタイムチャートとなるように、各間欠曝気槽の運転を制御し、かつ汚泥含有水の循環の開始のタイミング（繰り下げ時間α）を設定した以外は、実施例１と同様にして排水の処理を行った。
なお、実施例４の場合、１日のサイクル数が３回となり、１サイクルにおける各間欠曝気槽への原水投入量は、１．１１ｍ３（＝１０ｍ３／ｄ÷３回÷３槽）となる。
また、ｔ１とｔ２の最大公約数（ａ）は２であることから、ｔ１／ａ＋ｔ２／ａ＝４であり、上記式（１）を満たさなかった。
さらに、ｔ１／ｔ２＝３であり、上記式（２）も満たさなかった。 [Example 4]
Three intermittent aeration tanks, the volume of each intermittent aeration tank was changed to 6.7 m 3 , and in each intermittent aeration tank, the aeration time (t1) was 6 hours, the aeration stop time (t2) was 2 hours, As shown in the time chart of FIG. 6, drainage was performed in the same manner as in Example 1 except that the operation of each intermittent aeration tank was controlled and the timing of the start of circulation of the sludge-containing water (delaying time α) was set. Was performed.
In the case of Example 4, the number of cycles per day was three times, and the amount of raw water charged to each intermittent aeration tank in one cycle was 1.11 m 3 (= 10 m 3 / d ÷ 3 times ÷ 3 tanks). Become.
Further, since the greatest common divisor (a) of t1 and t2 is 2, t1 / a + t2 / a = 4, which did not satisfy the above expression (1).
Furthermore, t1 / t2 = 3, and the above-mentioned expression (2) was not satisfied.

実施例４の場合、１日当たりの膜濾過時間は２４時間であり、連続して膜濾過を実施できた。また、曝気停止状態の間欠曝気槽には汚泥含有水が返送されないので、曝気停止状態の間欠曝気槽内を無酸素状態に維持でき、安定した窒素処理を行うことができた。
また、中空糸膜の膜面積が２０ｍ２であることから、１０ｍ３／ｄの処理水を得るための平均膜濾過フラックスは０．５ｍ／ｄ（＝１０ｍ３／ｄ÷２０ｍ２）であり、安定した膜濾過の継続が可能であった。 In the case of Example 4, the membrane filtration time per day was 24 hours, and the membrane filtration could be performed continuously. Further, since the sludge-containing water is not returned to the intermittent aeration tank in the aeration stopped state, the inside of the intermittent aeration tank in the aeration stopped state can be maintained in an oxygen-free state, and a stable nitrogen treatment can be performed.
Further, since the membrane area of the hollow fiber membrane is 20 m 2 , the average membrane filtration flux for obtaining treated water of 10 m 3 / d is 0.5 m / d (= 10 m 3 / d ÷ 20 m 2 ), It was possible to continue stable membrane filtration.

しかし、図６に示すように、実施例４の場合、各間欠曝気槽における繰り下げ時間αが異なる。具体的には、第一の間欠曝気槽と膜分離槽との間での汚泥含有水の循環の開始が第一の間欠曝気槽での曝気工程の開始直後であるのに対し、残りの間欠曝気槽と膜分離槽との間での汚泥含有水の循環の開始は曝気工程の途中である。しかも、残りの間欠曝気槽同士においても、第二の間欠曝気槽と第三の間欠曝気槽とで繰り下げ時間αが異なる。そのため、各間欠曝気槽から膜分離槽へ移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度が異なり、第一の間欠曝気槽から膜分離槽に移送される汚泥含有水中のアンモニアおよび有機物のトータルの濃度が最も高くなる。よって、実施例１、２に比べて膜分離槽内の汚泥含有水の水質が安定しにくかった。
また、実施例４の場合、全ての間欠曝気槽が同時に曝気される時間帯が生じた（すなわち、上記条件（ｉ）を満たさない）。よって、実施例２の場合と間欠曝気槽の数は同じであるが、実施例４では３槽分の間欠曝気槽を曝気するだけの処理能力を有するブロアが必要であり、実施例２に比べて初期コストが増加した。
また、実施例４の場合、上記条件（iii）も満たさなかった。 However, as shown in FIG. 6, in the case of the fourth embodiment, the deferral time α in each intermittent aeration tank is different. Specifically, the circulation of the sludge-containing water between the first intermittent aeration tank and the membrane separation tank is started immediately after the start of the aeration step in the first intermittent aeration tank, while the remaining intermittent aeration is started. The start of the circulation of the sludge-containing water between the aeration tank and the membrane separation tank is in the middle of the aeration step. Moreover, even in the remaining intermittent aeration tanks, the second intermittent aeration tank and the third intermittent aeration tank have different deferring times α. Therefore, the total concentration of ammonia and organic matter in the sludge-containing water transferred from each intermittent aeration tank to the membrane separation tank is different, and the ammonia and organic substances in the sludge-containing water transferred from the first intermittent aeration tank to the membrane separation tank are different. Total concentration is highest. Therefore, the quality of the sludge-containing water in the membrane separation tank was less stable than in Examples 1 and 2.
Further, in the case of Example 4, there was a time zone in which all the intermittent aeration tanks were simultaneously aerated (that is, the condition (i) was not satisfied). Therefore, the number of intermittent aeration tanks is the same as in the case of the second embodiment. However, in the fourth embodiment, a blower having a processing capacity enough to aerate three intermittent aeration tanks is required. Increased initial costs.
In the case of Example 4, the above condition (iii) was not satisfied.

［比較例１］
図１２に示す排水の処理装置２を用い、間欠曝気槽を１槽とし、間欠曝気槽の容積を２０ｍ３に変更し、図１３（ｂ）に示すタイムチャートとなるように、曝気を停止している間は汚泥含有水の循環を停止した以外は実施例１と同様にして排水の処理を行った。図１２において、図１と同じ構成要素には同じ符号を付してその説明を省略する。
なお、比較例１の場合、１日のサイクル数が３回となり、１サイクルにおける間欠曝気槽への原水投入量は、３．３３ｍ３（＝１０ｍ３／ｄ÷３回÷１槽）となる。
また、ｔ１とｔ２の最大公約数（ａ）は４であることから、ｔ１／ａ＋ｔ２／ａ＝２であり、上記式（１）を満たさなかった。
さらに、ｔ１／ｔ２＝１であり、上記式（２）も満たさなかった。 [Comparative Example 1]
Using the wastewater treatment apparatus 2 shown in FIG. 12, the intermittent aeration tank was changed to one tank, the volume of the intermittent aeration tank was changed to 20 m 3 , and the aeration was stopped so as to obtain the time chart shown in FIG. During the operation, the wastewater was treated in the same manner as in Example 1 except that the circulation of the sludge-containing water was stopped. 12, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
In the case of Comparative Example 1, the number of cycles per day was three times, and the input amount of raw water into the intermittent aeration tank in one cycle was 3.33 m 3 (= 10 m 3 / d 3 times ÷ 1 tank). .
Further, since the greatest common divisor (a) of t1 and t2 is 4, t1 / a + t2 / a = 2, which did not satisfy the above expression (1).
Furthermore, t1 / t2 = 1, and the above-mentioned expression (2) was not satisfied.

比較例１の場合、曝気停止状態の間欠曝気槽には汚泥含有水が返送されないので、曝気停止状態の間欠曝気槽内を無酸素状態に維持でき、安定した窒素処理を行うことができた。
しかし、１日当たりの膜濾過時間は１２時間であり、各実施例に比べて濾過時間が著しく制限された。 In the case of Comparative Example 1, since the sludge-containing water was not returned to the intermittent aeration tank in the aeration stopped state, the inside of the intermittent aeration tank in the aeration stopped state could be maintained in an oxygen-free state, and a stable nitrogen treatment could be performed.
However, the membrane filtration time per day was 12 hours, and the filtration time was significantly restricted as compared with each Example.

また、中空糸膜の膜面積が２０ｍ２であることから、１０ｍ３／ｄの処理水を得るための平均膜濾過フラックスは１．０ｍ／ｄ［＝１０ｍ３／ｄ÷２０ｍ２×（２４時間÷１２時間）］である。
一般的に、産業排水を膜分離活性汚泥法で処理する場合の平均膜濾過フラックスは０．３〜０．６ｍ／ｄ程度が適切とされている。よって、比較例１における平均膜濾過フラックス（１．０ｍ／ｄ）は非常に高い値であり、安定した膜濾過が継続できないおそれがある。
なお、間欠曝気槽の容積が２０ｍ３であるため、２０ｍ３を曝気するだけの処理能力を有するブロアが必要であり、１０ｍ３分を交互に曝気する場合と比較して初期費用が増加することとなる。 Further, since the membrane area of the hollow fiber membrane is 20 m 2 , the average membrane filtration flux for obtaining 10 m 3 / d of treated water is 1.0 m / d [= 10 m 3 / d ÷ 20 m 2 × (24 hours {12 hours)].
In general, when treating industrial wastewater by the membrane separation activated sludge method, the average membrane filtration flux is appropriately about 0.3 to 0.6 m / d. Therefore, the average membrane filtration flux (1.0 m / d) in Comparative Example 1 is a very high value, and stable membrane filtration may not be continued.
In addition, since the volume of the intermittent aeration tank is 20 m 3 , a blower having a processing capacity enough to aerate 20 m 3 is required, and the initial cost is increased as compared with the case where 10 m 3 minutes are alternately aerated. Becomes

［比較例２］
図１２に示す排水の処理装置２を用い、比較例１と同様の条件で排水の処理を行った。ただし、１日あたりの処理水量は５ｍ３／ｄとした。
比較例２の場合、１日のサイクル数が３回となり、１サイクルにおける間欠曝気槽への原水投入量は、１．６７ｍ３（＝５ｍ３／ｄ÷３回÷１槽）となる。
また、ｔ１とｔ２の最大公約数（ａ）は４であることから、ｔ１／ａ＋ｔ２／ａ＝２であり、上記式（１）を満たさなかった。
さらに、ｔ１／ｔ２＝１であり、上記式（２）も満たさなかった。 [Comparative Example 2]
Using the waste water treatment apparatus 2 shown in FIG. 12, waste water was treated under the same conditions as in Comparative Example 1. However, the amount of treated water per day was 5 m 3 / d.
For Comparative Example 2, it is the number of cycles a day three times, the raw water input of the intermittent aeration tank in one cycle, a 1.67m 3 (= 5m 3 / d ÷ 3 times ÷ 1 tank).
Further, since the greatest common divisor (a) of t1 and t2 is 4, t1 / a + t2 / a = 2, which did not satisfy the above expression (1).
Furthermore, t1 / t2 = 1, and the above-mentioned expression (2) was not satisfied.

比較例２の場合、曝気停止状態の間欠曝気槽には汚泥含有水が返送されないので、曝気停止状態の間欠曝気槽内を無酸素状態に維持でき、安定した窒素処理を行うことができた。
しかし、１日当たりの膜濾過時間は１２時間であり、各実施例に比べて濾過時間が著しく制限された。 In the case of Comparative Example 2, since the sludge-containing water was not returned to the intermittent aeration tank in the aeration stopped state, the inside of the intermittent aeration tank in the aeration stopped state could be maintained in an oxygen-free state, and a stable nitrogen treatment could be performed.
However, the membrane filtration time per day was 12 hours, and the filtration time was significantly restricted as compared with each Example.

また、中空糸膜の膜面積が２０ｍ２であり、５ｍ３／ｄの処理水を得るための平均膜濾過フラックスは０．５ｍ／ｄ［＝５ｍ３／ｄ÷２０ｍ２×（２４時間÷１２時間）］であり、安定した膜濾過の継続が可能であった。
なお、間欠曝気槽の容積が２０ｍ３であるため、２０ｍ３を曝気するだけの処理能力を有するブロアが必要であり、１０ｍ３分を交互に曝気する場合と比較して初期費用が増加することとなる。 The membrane area of the hollow fiber membrane is 20 m 2 , and the average membrane filtration flux for obtaining 5 m 3 / d of treated water is 0.5 m / d [= 5 m 3 / d ÷ 20 m 2 × (24 hours ÷ 12 Time)], and stable membrane filtration could be continued.
In addition, since the volume of the intermittent aeration tank is 20 m 3 , a blower having a processing capacity enough to aerate 20 m 3 is required, and the initial cost is increased as compared with the case where 10 m 3 minutes are alternately aerated. Becomes

［比較例３］
図１２に示す排水の処理装置２を用い、比較例１と同様の条件で排水の処理を行った。ただし、中空糸膜の膜面積は４０ｍ２とした。
比較例３の場合、１日のサイクル数が３回となり、１サイクルにおける間欠曝気槽への原水投入量は、３．３３ｍ３（＝１０ｍ３／ｄ÷３回÷１槽）となる。
また、ｔ１とｔ２の最大公約数（ａ）は４であることから、ｔ１／ａ＋ｔ２／ａ＝２であり、上記式（１）を満たさなかった。
さらに、ｔ１／ｔ２＝１であり、上記式（２）も満たさなかった。 [Comparative Example 3]
Using the waste water treatment apparatus 2 shown in FIG. 12, waste water was treated under the same conditions as in Comparative Example 1. However, the membrane area of the hollow fiber membrane was 40 m 2 .
In the case of Comparative Example 3, the number of cycles per day is three, and the input amount of raw water to the intermittent aeration tank in one cycle is 3.33 m 3 (= 10 m 3 / d ÷ 3 times ÷ 1 tank).
Further, since the greatest common divisor (a) of t1 and t2 is 4, t1 / a + t2 / a = 2, which did not satisfy the above expression (1).
Furthermore, t1 / t2 = 1, and the above-mentioned expression (2) was not satisfied.

比較例３の場合、曝気停止状態の間欠曝気槽には汚泥含有水が返送されないので、曝気停止状態の間欠曝気槽内を無酸素状態に維持でき、安定した窒素処理を行うことができた。
しかし、１日当たりの膜濾過時間は１２時間であり、各実施例に比べて濾過時間が著しく制限された。 In the case of Comparative Example 3, since the sludge-containing water was not returned to the intermittent aeration tank in the aeration stopped state, the inside of the intermittent aeration tank in the aeration stopped state could be maintained in an oxygen-free state, and a stable nitrogen treatment could be performed.
However, the membrane filtration time per day was 12 hours, and the filtration time was significantly restricted as compared with each Example.

また、中空糸膜の膜面積が４０ｍ２であり、１０ｍ３／ｄの処理水を得るための平均膜濾過フラックスは０．５ｍ／ｄ［＝１０ｍ３／ｄ÷４０ｍ２×（２４時間÷１２時間）］であり、安定した膜濾過の継続が可能であった。しかし、膜面積が４０ｍ２の濾過膜を使用する必要があり、初期費用（設備投資など）が増加することとなる。
なお、間欠曝気槽の容積が２０ｍ３であるため、２０ｍ３を曝気するだけの処理能力を有するブロアが必要であり、１０ｍ３分を交互に曝気する場合と比較して初期費用が増加することとなる。 Further, the membrane area of the hollow fiber membrane is 40 m 2 , and the average membrane filtration flux for obtaining treated water of 10 m 3 / d is 0.5 m / d [= 10 m 3 / dｍ40 m 2 × (24 hours ÷ 12 Time)], and stable membrane filtration could be continued. However, it is necessary to use a filtration membrane having a membrane area of 40 m 2 , which increases initial costs (e.g., capital investment).
In addition, since the volume of the intermittent aeration tank is 20 m 3 , a blower having a processing capacity enough to aerate 20 m 3 is required, and the initial cost is increased as compared with the case where 10 m 3 minutes are alternately aerated. Becomes

１ 排水の処理装置
２ 排水の処理装置
１０ 間欠曝気槽
１０ａ 第一の間欠曝気槽
１０ｂ 第二の間欠曝気槽
１１ 散気管
１２ 攪拌手段
１３ 導入管
１３ａ 開閉バルブ
１３ｂ 開閉バルブ
１４ ブロア
１５ ブロア制御装置
１６ 被処理水流路
１６ａ 開閉バルブ
１６ｂ 開閉バルブ
１７ 汚泥含有水流路
１８ 原水ポンプ
２０ 膜分離槽
２１ 散気管
２２ 膜モジュール
２３ 導入管
２４ ブロア
２５ 透過水流路
２６ 膜濾過ポンプ
２７ 返送流路
２７ａ 開閉バルブ
２７ｂ 開閉バルブ
２８ 循環ポンプ REFERENCE SIGNS LIST 1 wastewater treatment device 2 wastewater treatment device 10 intermittent aeration tank 10 a first intermittent aeration tank 10 b second intermittent aeration tank 11 diffuser pipe 12 stirring means 13 introduction pipe 13 a open / close valve 13 b open / close valve 14 blower 15 blower control device 16 Processed water flow path 16a Open / close valve 16b Open / close valve 17 Sludge-containing water flow path 18 Raw water pump 20 Membrane separation tank 21 Air diffuser 22 Membrane module 23 Inlet pipe 24 Blower 25 Permeate water flow path 26 Membrane filtration pump 27 Return flow path 27a Open / close valve 27b Open / close Valve 28 Circulation pump

Claims (6)

被処理水を間欠曝気槽に導き、曝気と曝気停止とを繰り返して、活性汚泥により生物処理する間欠曝気工程と、
間欠曝気槽内の生物処理水と活性汚泥とからなる汚泥含有水を膜分離槽に移送して膜濾過する膜濾過工程と、
膜分離槽から間欠曝気槽に、膜分離槽内の汚泥含有水の一部を返送させる返送工程とを有する、間欠曝気膜分離活性汚泥法により排水を処理する方法において、
前記間欠曝気槽を複数用い、排水処理を行っている間は１槽以上の間欠曝気槽が曝気状態となるように、各間欠曝気槽の運転を制御し、
汚泥含有水の移送および返送を曝気状態にある間欠曝気槽と膜分離槽との間で行う、排水の処理方法。 Intermittent aeration step of introducing the water to be treated to an intermittent aeration tank, repeating aeration and aeration stop, and biologically treating with activated sludge;
A membrane filtration step of transferring sludge-containing water consisting of biologically treated water and activated sludge in an intermittent aeration tank to a membrane separation tank and performing membrane filtration,
A return step of returning a part of the sludge-containing water in the membrane separation tank from the membrane separation tank to the intermittent aeration tank, wherein the wastewater is treated by the intermittent aeration membrane separation activated sludge method.
Using a plurality of the intermittent aeration tanks, while operating the wastewater treatment, control the operation of each intermittent aeration tank so that one or more intermittent aeration tanks are in an aerated state,
A method for treating wastewater, comprising transferring and returning sludge-containing water between an intermittent aeration tank in an aerated state and a membrane separation tank. 間欠曝気槽の数をｎとし、間欠曝気工程における曝気時間をｔ１、曝気停止時間をｔ２とし、ｔ１とｔ２の最大公約数をａとしたときに、下記式（１）を満たす、請求項１に記載の排水の処理方法。
ｎ＝ｔ１／ａ＋ｔ２／ａ ・・・（１） The following formula (1) is satisfied when the number of intermittent aeration tanks is n, the aeration time in the intermittent aeration step is t1, the aeration stop time is t2, and the greatest common divisor of t1 and t2 is a. A method for treating wastewater according to item 1.
n = t1 / a + t2 / a (1) 曝気状態にある間欠曝気槽と膜分離槽との間で行われる汚泥含有水の移送および返送の開始を、その間欠曝気槽での曝気開始から遅らせる、請求項２に記載の排水の処理方法。   The method for treating wastewater according to claim 2, wherein the start of the transfer and return of the sludge-containing water performed between the intermittent aeration tank and the membrane separation tank in the aerated state is delayed from the start of the aeration in the intermittent aeration tank. 全ての間欠曝気槽の運転のタイミングが異なるように、各間欠曝気槽の曝気を制御する、請求項１〜３のいずれか一項に記載の排水の処理方法。   The wastewater treatment method according to any one of claims 1 to 3, wherein the aeration of each intermittent aeration tank is controlled such that the operation timings of all the intermittent aeration tanks are different. 被処理水が導かれ、曝気と曝気停止とを繰り返して、活性汚泥により生物処理する間欠曝気槽と、
間欠曝気槽内の生物処理水と活性汚泥とからなる汚泥含有水を膜濾過する膜分離槽と、
膜分離槽から間欠曝気槽に、膜分離槽内の汚泥含有水の一部を返送させる返送手段とを備えた、間欠曝気膜分離活性汚泥法により排水を処理する装置において、
前記間欠曝気槽を複数備え、排水処理を行っている間は１槽以上の間欠曝気槽が曝気状態となるように、各間欠曝気槽の運転が制御され、
汚泥含有水の移送および返送が曝気状態にある間欠曝気槽と膜分離槽との間で行われる、排水の処理装置。 An intermittent aeration tank where the water to be treated is guided, repeating aeration and aeration stop, and biologically treating with activated sludge,
A membrane separation tank for membrane-filtering sludge-containing water consisting of biologically treated water and activated sludge in an intermittent aeration tank;
From the membrane separation tank to the intermittent aeration tank, with a return means for returning a part of the sludge-containing water in the membrane separation tank, in an apparatus for treating wastewater by intermittent aeration membrane separation activated sludge method,
The operation of each intermittent aeration tank is controlled so that a plurality of the intermittent aeration tanks are provided and one or more intermittent aeration tanks are in an aerated state during the drainage treatment.
An apparatus for treating wastewater in which transfer and return of sludge-containing water are performed between an intermittent aeration tank and a membrane separation tank in an aerated state. 全ての間欠曝気槽の運転のタイミングが異なるように、各間欠曝気槽の曝気が制御されている、請求項５に記載の排水の処理装置。   The wastewater treatment apparatus according to claim 5, wherein the aeration of each intermittent aeration tank is controlled such that the operation timings of all the intermittent aeration tanks are different.
JP2016025837A 2015-03-16 2016-02-15 Wastewater treatment method and wastewater treatment device Active JP6634862B2 (en)

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