JP6744714B2 - Wastewater treatment system - Google Patents

Wastewater treatment system Download PDF

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JP6744714B2
JP6744714B2 JP2015248034A JP2015248034A JP6744714B2 JP 6744714 B2 JP6744714 B2 JP 6744714B2 JP 2015248034 A JP2015248034 A JP 2015248034A JP 2015248034 A JP2015248034 A JP 2015248034A JP 6744714 B2 JP6744714 B2 JP 6744714B2
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岡村　知也
知也 岡村
宮田　篤
篤 宮田
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Metawater Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • 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、排水を処理する排水処理システムに関する。 The present invention relates to a wastewater treatment system for treating wastewater.

生活排水又は工場排水等の排水（下水）を処理する排水処理システムとして、例えば特許文献１に示すように、標準活性汚泥法による排水処理システムが実用化されている。 As a wastewater treatment system for treating wastewater (sewage) such as domestic wastewater or factory wastewater, a wastewater treatment system using a standard activated sludge method has been put into practical use as shown in Patent Document 1, for example.

特開２００８−２５３９９４号公報JP, 2008-253994, A

標準活性汚泥法による排水処理システムでは、反応タンク内に処理対象の排水を流入しつつ、この反応タンク内に存在する多種類の好気性微生物に対して酸素を供給する曝気処理を行う。これによって、反応タンク内の排水中に含まれる有機物は、好気性微生物の作用によって分解処理され、この結果、安定した処理水質が得られる。 In the wastewater treatment system using the standard activated sludge method, while the wastewater to be treated flows into the reaction tank, aeration treatment is performed in which oxygen is supplied to many kinds of aerobic microorganisms present in the reaction tank. As a result, the organic matter contained in the waste water in the reaction tank is decomposed by the action of aerobic microorganisms, and as a result, stable treated water quality is obtained.

しかし、標準活性汚泥法による排水処理システムでは、曝気処理に多くの電力が消費されるため、排水処理時の電気代が高額化する。また、排水処理過程において発生する汚泥の処理に、多額の費用が必要となる。この結果、標準活性汚泥法による排水処理システムでは、他の方式に比して排水処理時のランニングコストが高額になるという問題がある。従って、近年、散水ろ床法による排水処理システムが見直されつつある。 However, in the wastewater treatment system using the standard activated sludge method, a large amount of electric power is consumed for the aeration treatment, so that the electricity bill for the wastewater treatment becomes expensive. In addition, a large amount of cost is required to treat the sludge generated in the wastewater treatment process. As a result, the wastewater treatment system using the standard activated sludge method has a problem that the running cost at the time of wastewater treatment becomes higher than that of other methods. Therefore, in recent years, the wastewater treatment system by the sprinkling filter method is being reviewed.

散水ろ床法では、砕石等のろ材を層上に堆積したろ材層を有し、各ろ材の表面に微生物を担持させた散水ろ床を用いる。散水ろ床法では、この散水ろ床の上方から排水を散布し、排水をろ材層の空隙に通しつつ、排水中の有機物を微生物により分解処理する。分解処理された排水は、散水ろ床の底部から、外部に排出される。この散水ろ床法では、曝気処理を行わないため、消費電力を低減でき、電気代の高額化を抑制することが可能となる。 In the sprinkling filter method, a sprinkling filter having a filter medium layer in which a filter medium such as crushed stone is deposited on a layer and carrying microorganisms on the surface of each filter medium is used. In the sprinkling filter method, wastewater is sprayed from above the sprinkling filter bed, and the organic matter in the wastewater is decomposed by microorganisms while passing the wastewater through the voids of the filter medium layer. The decomposed wastewater is discharged to the outside from the bottom of the sprinkling filter. In this sprinkling filter method, since aeration treatment is not performed, it is possible to reduce power consumption and suppress an increase in the cost of electricity.

しかし、この散水ろ床法では、排水をろ材層の空隙に通すため、ろ材表面の微生物が、排水と共に外部に排出されるおそれがある。この場合、ろ材表面の微生物の数が減少して、排水処理の性能が低下する可能性がある。結果として、アンモニア性窒素が十分に酸化分解されていない排水が排出されるおそれが生じる。 However, in this sprinkling filter method, since the wastewater is passed through the voids of the filter medium layer, the microorganisms on the surface of the filter medium may be discharged outside together with the wastewater. In this case, the number of microorganisms on the surface of the filter medium may decrease, and the performance of wastewater treatment may deteriorate. As a result, there is a risk that wastewater in which ammoniacal nitrogen is not sufficiently oxidized and decomposed will be discharged.

本発明は、上記に鑑みてなされたものであって、消費電力を低減しつつ、排水処理の性能低下を抑制する排水処理システムを提供することを目的とする。 The present invention has been made in view of the above, and an object of the present invention is to provide a wastewater treatment system that suppresses deterioration of performance of wastewater treatment while reducing power consumption.

上述した課題を解決し、目的を達成するために、本開示の排水処理システムは、微生物を担持させた複数のろ材を有するろ材充填層を有し、前記ろ材充填層の上部に処理用排水を散布して前記ろ材充填層内に前記処理用排水を流下させ、前記微生物により前記処理用排水を生物処理して得た処理水を流出する散水ろ床部と、ろ過膜を有し、前記散水ろ床部の後段に設けられて、前記処理水を、前記ろ過膜を透過してない膜濃縮水と、前記ろ過膜を透過したろ過水とに分離する膜ろ過部と、前記膜ろ過部と前記散水ろ床部とを接続し、前記膜濃縮水を前記ろ材充填層に返送する散水ろ床接続管と、を有する。 In order to solve the above-mentioned problems and achieve the object, the wastewater treatment system of the present disclosure has a filter medium-filled layer having a plurality of filter media supporting microorganisms, and the treatment wastewater is provided above the filter medium-filled layer. The sprinkling filter bed part for spraying and flowing down the treatment wastewater into the filter medium packed bed, and flowing out the treated water obtained by biologically treating the treatment wastewater with the microorganisms, and having a filtration membrane, the sprinkling water Provided in the subsequent stage of the filter bed, the treated water, a membrane filtration unit that separates the membrane concentrated water that has not passed through the filtration membrane and the filtered water that has passed through the filtration membrane, and the membrane filtration unit. And a sprinkling filter connection pipe that connects the sprinkling filter section and returns the membrane concentrated water to the filter medium packed bed.

前記排水処理システムは、前記処理水又は前記ろ過水の水質を測定する水質測定部と、前記水質測定部の測定結果に基づき、前記ろ材充填層への前記膜濃縮水の返送量を決定する制御部と、を有することが好ましい。 The wastewater treatment system is a water quality measurement unit that measures the water quality of the treated water or the filtered water, and a control that determines the amount of the membrane concentrated water to be returned to the filter medium packed layer based on the measurement result of the water quality measurement unit. And part.

前記排水処理システムにおいて、前記水質測定部は、前記処理水のアンモニア性窒素濃度、前記処理水の溶存酸素量、前記ろ過水のアンモニア性窒素濃度、及び前記ろ過水の溶存酸素量のうち、少なくともいずれか１つを検出し、前記制御部は、検出された前記処理水のアンモニア性窒素濃度、前記処理水の溶存酸素量、前記ろ過水のアンモニア性窒素濃度、及び前記ろ過水の溶存酸素量のうち、少なくともいずれか１つに基づき、前記ろ材充填層への前記膜濃縮水の返送量を決定することが好ましい。 In the wastewater treatment system, the water quality measurement unit is at least an ammoniacal nitrogen concentration of the treated water, a dissolved oxygen amount of the treated water, an ammoniacal nitrogen concentration of the filtered water, and a dissolved oxygen amount of the filtered water. Detecting any one of them, the control unit detects the ammonia nitrogen concentration of the treated water, the dissolved oxygen amount of the treated water, the ammonia nitrogen concentration of the filtered water, and the dissolved oxygen amount of the filtered water detected. It is preferable to determine the return amount of the membrane concentrated water to the filter medium packed bed based on at least one of the above.

前記排水処理システムにおいて、前記制御部は、前記アンモニア性窒素濃度が所定濃度より高くなった場合、又は前記溶存酸素量が所定量より減少した場合に、前記ろ材充填層への前記膜濃縮水の返送量を増加させることが好ましい。 In the wastewater treatment system, the control unit, when the ammonia nitrogen concentration is higher than a predetermined concentration, or when the dissolved oxygen amount is lower than a predetermined amount, the membrane concentrated water to the filter medium packed bed. It is preferable to increase the return amount.

前記排水処理システムにおいて、前記水質測定部は、前記処理用排水の水質も測定し、前記制御部は、前記処理用排水と、前記処理水又は前記ろ過水との間の水質の比較結果に基づき、前記ろ材充填層への前記膜濃縮水の返送量を決定することが好ましい。 In the wastewater treatment system, the water quality measurement unit also measures the water quality of the treatment wastewater, the control unit, based on the comparison result of the water quality between the treatment wastewater and the treated water or the filtered water. It is preferable to determine the return amount of the membrane concentrated water to the filter medium packed bed.

前記排水処理システムは、前記散水ろ床部よりも前段に設けられ、排水を固形成分と前記処理用排水とに分離する固液分離部と、前記散水ろ床部と前記固液分離部とを接続し、前記膜濃縮水を前記固液分離部に返送する固液分離接続管と、をさらに有することが好ましい。 The wastewater treatment system is provided in a stage before the sprinkling filter section, and includes a solid-liquid separating section that separates wastewater into solid components and the processing wastewater, the sprinkling filter section and the solid-liquid separating section. It is preferable to further include a solid-liquid separation connection pipe that is connected and returns the membrane concentrated water to the solid-liquid separation section.

前記排水処理システムは、前記散水ろ床部よりも前段に設けられ、排水を固形成分と前記処理用排水とに分離する固液分離部と、前記膜ろ過部と前記固液分離部とを接続し、前記膜濃縮水を前記固液分離部に返送する固液分離接続管と、をさらに有し、前記制御部は、前記水質測定部の測定結果に基づき、前記ろ材充填層と前記固液分離部とへの前記膜濃縮水の返送量の割合を決定することが好ましい。 The wastewater treatment system is provided before the sprinkling filter section, and connects the solid-liquid separation unit that separates wastewater into solid components and the treatment wastewater, the membrane filtration unit, and the solid-liquid separation unit. Then, further comprising a solid-liquid separation connection pipe for returning the membrane concentrated water to the solid-liquid separation unit, the control unit, based on the measurement result of the water quality measurement unit, the filter medium packed layer and the solid-liquid It is preferable to determine the ratio of the amount of the membrane concentrated water returned to the separation section.

前記排水処理システムにおいて、前記水質測定部は、前記処理水又は前記ろ過水のアンモニア性窒素濃度、又は溶存酸素量を検出し、前記制御部は、前記アンモニア性窒素濃度が所定濃度より高くなった場合、又は前記溶存酸素量が所定量より減少した場合に、前記ろ材充填層への前記膜濃縮水の返送量の割合を高くし、前記固液分離部への前記膜濃縮水の返送量の割合を低くすることが好ましい。 In the wastewater treatment system, the water quality measuring unit detects an ammoniacal nitrogen concentration of the treated water or the filtered water, or a dissolved oxygen amount, and the control unit has the ammoniacal nitrogen concentration higher than a predetermined concentration. In the case, or when the amount of dissolved oxygen decreases below a predetermined amount, the ratio of the amount of the membrane concentrated water returned to the filter medium packed bed is increased, and the amount of the membrane concentrated water returned to the solid-liquid separation unit is It is preferable to lower the ratio.

前記排水処理システムにおいて、前記制御部は、前記ろ材充填層を逆洗浄した直後に、前記ろ材充填層への前記膜濃縮水の返送量を増加させることが好ましい。 In the wastewater treatment system, it is preferable that the control unit increase the amount of the membrane concentrated water returned to the filter medium packed layer immediately after backwashing the filter medium packed layer.

前記排水処理システムにおいて、前記ろ過膜は、精密ろ過膜、又は限外ろ過膜であることが好ましい。 In the wastewater treatment system, the filtration membrane is preferably a microfiltration membrane or an ultrafiltration membrane.

本発明によれば、消費電力を低減しつつ、排水処理の性能低下を抑制することができる。 ADVANTAGE OF THE INVENTION According to this invention, the power consumption can be reduced and the performance degradation of wastewater treatment can be suppressed.

第１実施形態に係る排水処理システムの概略構成を示すブロック図である。It is a block diagram showing a schematic structure of a wastewater treatment system concerning a 1st embodiment. 第１実施形態に係る固液分離部の一構成例を示す模式図である。It is a schematic diagram which shows one structural example of the solid-liquid separation part which concerns on 1st Embodiment. 第１実施形態に係る排水処理システムの散水ろ床部の一構成例を示す模式図である。It is a schematic diagram which shows one structural example of the sprinkling filter part of the wastewater treatment system which concerns on 1st Embodiment. 第１実施形態に係る散水ろ床部の処理水槽の一構成例を示す模式図である。It is a schematic diagram which shows one structural example of the treated water tank of the sprinkling filter part which concerns on 1st Embodiment. 第１実施形態に係る膜ろ過部の一構成例を示す模式図である。It is a schematic diagram which shows one structural example of the membrane filtration part which concerns on 1st Embodiment. 膜濃縮水の返送量の変更例を説明する表である。It is a table explaining an example of changing the return amount of the membrane concentrated water. 第１実施形態に係る膜濃縮水の返送量の制御を説明するフローチャートである。It is a flowchart explaining the control of the return amount of the membrane concentrated water according to the first embodiment. ろ床返送量の制御の一例を説明するグラフである。It is a graph explaining an example of control of a filter bed return amount. 第２実施形態に係る排水処理システムの概略構成を示すブロック図である。It is a block diagram which shows schematic structure of the wastewater treatment system which concerns on 2nd Embodiment. 変形例に係る排水処理システムの概略構成を示すブロック図である。It is a block diagram which shows schematic structure of the wastewater treatment system which concerns on a modification.

以下に、本発明に係る排水処理システムの好適な実施形態を図面に基づいて詳細に説明する。なお、以下に説明する実施形態により本発明が限定されるものではない。 Hereinafter, preferred embodiments of the wastewater treatment system according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below.

（第１実施形態）
図１は、第１実施形態に係る排水処理システムの概略構成を示すブロック図である。図１に示すように、第１実施形態に係る排水処理システム１は、固液分離部２と、散水ろ床部３と、膜ろ過部４と、水質測定部５と、制御部６と、排水管１１と、処理用排水管１２と、処理水管１３と、ろ過水管１４と、膜濃縮水管１６と、散水ろ床接続管１７と、固液分離接続管１８と、を有する。 (First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a wastewater treatment system according to the first embodiment. As shown in FIG. 1, the wastewater treatment system 1 according to the first embodiment includes a solid-liquid separation unit 2, a sprinkling filter unit 3, a membrane filtration unit 4, a water quality measurement unit 5, and a control unit 6. A drainage pipe 11, a treatment drainage pipe 12, a treated water pipe 13, a filtered water pipe 14, a membrane concentrated water pipe 16, a sprinkling filter connection pipe 17, and a solid-liquid separation connection pipe 18.

固液分離部２は、処理対象となる排水Ｗ１に対する第１段階目の浄化処理を行う。固液分離部２は、処理対象の排水Ｗ１に対して固液分離処理を行って処理用排水Ｗ２を得る。具体的には、固液分離部２は、生活排水及び工場排水等の排水Ｗ１を受け入れ、この排水Ｗ１の固液分離処理を行って、処理用排水Ｗ２を得るものである。固液分離部２は、排水Ｗ１の固液分離処理を行うために必要なろ過手段を洗浄する逆洗浄機能を有し、所定のタイミングに、この逆洗浄機能を有効にする。 The solid-liquid separation unit 2 performs the first-stage purification process on the wastewater W1 to be treated. The solid-liquid separation unit 2 performs a solid-liquid separation process on the wastewater W1 to be treated to obtain a treatment wastewater W2. Specifically, the solid-liquid separation unit 2 receives wastewater W1 such as domestic wastewater and factory wastewater, performs solid-liquid separation processing of this wastewater W1, and obtains treatment wastewater W2. The solid-liquid separation unit 2 has a back-cleaning function for cleaning the filtering means necessary for performing the solid-liquid separation processing of the wastewater W1, and makes this back-cleaning function effective at a predetermined timing.

散水ろ床部３は、処理対象の排水Ｗ１に対する第２段階目の浄化処理を行う。散水ろ床部３は、処理用排水Ｗ２に対して生物処理を行って処理水Ｗ３を得る。散水ろ床部３は、固液分離部２の後段（すなわち処理用排水Ｗ２の下流側）に設置され、固液分離部２によって得られた処理用排水Ｗ２を受け入れる。ついで、散水ろ床部３は、この処理用排水Ｗ２を生物処理して、処理水Ｗ３を得る。その後、散水ろ床部３は、膜ろ過部４に処理水Ｗ３を送出する。また、散水ろ床部３は、この処理用排水Ｗ２の生物処理に必要なろ過手段の洗浄機能を有し、所定のタイミングに、この洗浄機能を有効にする。 The sprinkling filter part 3 performs the second-stage purification process for the wastewater W1 to be treated. The sprinkling filter part 3 performs biological treatment on the treatment wastewater W2 to obtain treated water W3. The sprinkling filter section 3 is installed in the latter stage of the solid-liquid separation section 2 (that is, on the downstream side of the processing wastewater W2) and receives the processing wastewater W2 obtained by the solid-liquid separation section 2. Next, the sprinkling filter part 3 biologically treats this treatment wastewater W2 to obtain treated water W3. Then, the sprinkling filter part 3 sends the treated water W3 to the membrane filtering part 4. Further, the sprinkling filter part 3 has a cleaning function of the filtering means necessary for biological treatment of the treatment wastewater W2, and makes this cleaning function effective at a predetermined timing.

膜ろ過部４は、処理対象の排水Ｗ１に対する第３段階目の浄化処理を行う。膜ろ過部４は、散水ろ床部３を通過した処理水Ｗ３に対して固液分離処理を行って、処理水Ｗ３をろ過水Ｗ４と膜濃縮水Ｗ５とに分離する。膜ろ過部４は、ろ過膜を有する。膜ろ過部４は、散水ろ床部３の後段（すなわち処理水Ｗ３の下流側）に設置されるろ過手段である。膜ろ過部４は、散水ろ床部３によって得られた処理水Ｗ３を受け入れて、処理水Ｗ３を、ろ過膜を透過したろ過水Ｗ４と、ろ過膜を透過していない膜濃縮水Ｗ５とに分離する。ろ過膜は、処理水Ｗ３中の微細な固形成分、及び処理水Ｗ３に含まれる微生物を捕集する。そのため、ろ過水Ｗ４には、このろ過膜を透過しなかった微生物等が含まれず、膜濃縮水Ｗ５には、このろ過膜を透過しなかった微生物等が含まれる。 The membrane filtration unit 4 performs the third-stage purification process on the wastewater W1 to be treated. The membrane filtration unit 4 performs a solid-liquid separation process on the treated water W3 that has passed through the sprinkling filter unit 3 to separate the treated water W3 into filtered water W4 and membrane concentrated water W5. The membrane filtration unit 4 has a filtration membrane. The membrane filtration unit 4 is a filtration unit installed in the latter stage of the sprinkling filter unit 3 (that is, on the downstream side of the treated water W3). The membrane filtration unit 4 receives the treated water W3 obtained by the sprinkling filter unit 3 and transforms the treated water W3 into filtered water W4 that has passed through the filtration membrane and membrane concentrated water W5 that has not passed through the filtration membrane. To separate. The filtration membrane collects fine solid components in the treated water W3 and microorganisms contained in the treated water W3. Therefore, the filtered water W4 does not include microorganisms that have not permeated the filtration membrane, and the membrane-concentrated water W5 includes microorganisms that have not permeated the filtration membrane.

排水管１１と、処理用排水管１２と、処理水管１３と、ろ過水管１４と、膜濃縮水管１６と、散水ろ床接続管１７と、固液分離接続管１８と、は、いずれも水が流れる通路、本実施形態では配管である。各部の配置と流れる水について説明する。排水管１１は、固液分離部２の上流側に接続され、固液分離部２に排水Ｗ１を流入させる。処理用排水管１２は、一方の端部が固液分離部２の下流側に接続され、他方の端部が散水ろ床部３の上流側に接続される。処理用排水管１２は、固液分離部２と散水ろ床部３とを接続し、固液分離部２からの処理用排水Ｗ２を散水ろ床部３に供給する。処理水管１３は、一方の端部が散水ろ床部３の下流側に接続され、他方の端部が膜ろ過部４の上流側に接続される。処理水管１３は、散水ろ床部３と膜ろ過部４とを接続して、散水ろ床部３からの処理水Ｗ３を膜ろ過部４に供給する。ろ過水管１４は、膜ろ過部４の下流側に接続され、膜ろ過部４からろ過水Ｗ４を排出する。 The drainage pipe 11, the treatment drainage pipe 12, the treated water pipe 13, the filtered water pipe 14, the membrane concentrated water pipe 16, the sprinkling filter connection pipe 17, and the solid-liquid separation connection pipe 18 all contain water. A flow passage, which is a pipe in this embodiment. The arrangement of each part and flowing water will be described. The drain pipe 11 is connected to the upstream side of the solid-liquid separation section 2 and causes the waste water W1 to flow into the solid-liquid separation section 2. One end of the treatment drainage pipe 12 is connected to the downstream side of the solid-liquid separation unit 2, and the other end is connected to the upstream side of the sprinkling filter unit 3. The treatment drainage pipe 12 connects the solid-liquid separation unit 2 and the sprinkling filter unit 3 and supplies the treatment drainage W2 from the solid-liquid separating unit 2 to the sprinkling filter unit 3. One end of the treated water pipe 13 is connected to the downstream side of the sprinkling filter unit 3, and the other end is connected to the upstream side of the membrane filtration unit 4. The treated water pipe 13 connects the sprinkling filter section 3 and the membrane filtering section 4 and supplies the treated water W3 from the sprinkling filter section 3 to the membrane filtering section 4. The filtered water pipe 14 is connected to the downstream side of the membrane filtration unit 4 and discharges the filtered water W4 from the membrane filtration unit 4.

膜濃縮水管１６は、膜ろ過部４に接続され、膜ろ過部４から膜濃縮水Ｗ５を排出する。散水ろ床接続管１７は、膜濃縮水管１６と散水ろ床部３とを接続して、膜濃縮水管１６からの膜濃縮水Ｗ５を、散水ろ床部３の上流（固液分離部２と散水ろ床部３との間）に供給する。散水ろ床接続管１７には、膜濃縮水管１６からの膜濃縮水Ｗ５の供給量を制御するための膜濃縮水供給弁１７ａが設けられている。固液分離接続管１８は、膜濃縮水管１６と固液分離部２とを接続して、膜濃縮水管１６からの膜濃縮水Ｗ５を、固液分離部２の上流に供給する。固液分離接続管１８には、膜濃縮水管１６からの膜濃縮水Ｗ５の供給量を制御するための膜濃縮水供給弁１８ａが設けられている。水質測定部５は、処理用排水Ｗ２と処理水Ｗ３との水質を計測するセンサーである。制御部６は、水質測定部５の水質測定結果に基づいて、膜濃縮水供給弁１７ａ、及び膜濃縮水供給弁１８ａの開閉を制御して、膜濃縮水Ｗ５の供給を制御する。 The membrane concentrated water pipe 16 is connected to the membrane filtration unit 4 and discharges the membrane concentrated water W5 from the membrane filtration unit 4. The water sprinkling filter connection pipe 17 connects the membrane concentrated water pipe 16 and the water sprinkling filter section 3 so that the membrane concentrated water W5 from the membrane condensing water pipe 16 is upstream of the water sprinkling filter section 3 (solid-liquid separation unit 2 and Between the sprinkling filter part 3). The sprinkling filter connection pipe 17 is provided with a membrane concentrated water supply valve 17a for controlling the supply amount of the membrane concentrated water W5 from the membrane concentrated water pipe 16. The solid-liquid separation connection pipe 18 connects the membrane concentrated water pipe 16 and the solid-liquid separation unit 2 and supplies the membrane concentrated water W5 from the membrane concentrated water pipe 16 to the upstream of the solid-liquid separation unit 2. The solid-liquid separation connecting pipe 18 is provided with a membrane concentrated water supply valve 18a for controlling the supply amount of the membrane concentrated water W5 from the membrane concentrated water pipe 16. The water quality measurement unit 5 is a sensor that measures the water quality of the treated wastewater W2 and the treated water W3. The control unit 6 controls opening and closing of the membrane concentrated water supply valve 17a and the membrane concentrated water supply valve 18a based on the water quality measurement result of the water quality measurement unit 5 to control the supply of the membrane concentrated water W5.

（固液分離部について）
次に、図１に示した固液分離部２について詳細に説明する。ここでは、まず、固液分離部２の構成について説明し、その後、固液分離部２による排水Ｗ１の固液分離処理について説明する。 (About solid-liquid separation section)
Next, the solid-liquid separation unit 2 shown in FIG. 1 will be described in detail. Here, first, the configuration of the solid-liquid separation unit 2 will be described, and then the solid-liquid separation processing of the wastewater W1 by the solid-liquid separation unit 2 will be described.

図２は、第１実施形態に係る固液分離部の一構成例を示す模式図である。図２に示すように、この固液分離部２は、排水Ｗ１を貯留する分配槽２０及びろ過水槽２１を備える。また、固液分離部２は、この排水Ｗ１の固液分離処理を行うためのろ材充填層２２と、この固液分離処理によって得られた処理用排水Ｗ２を貯留する共通ろ過水槽２３とを備える。さらに、固液分離部２は、排水Ｗ１を流通するための複数の流入配管２１ａ〜２１ｄ、分配管２４、弁２４ａ〜２４ｄ及びポンプ２４ｅと、処理用排水管１２を介して処理用排水Ｗ２を散水ろ床部３へ流通するための開水路２５とを備える。 FIG. 2 is a schematic diagram showing a configuration example of the solid-liquid separation unit according to the first embodiment. As shown in FIG. 2, the solid-liquid separation unit 2 includes a distribution tank 20 that stores the drainage W1 and a filtered water tank 21. Further, the solid-liquid separation unit 2 includes a filter medium filling layer 22 for performing the solid-liquid separation treatment of the wastewater W1 and a common filtered water tank 23 for storing the treatment wastewater W2 obtained by the solid-liquid separation treatment. .. Further, the solid-liquid separation unit 2 discharges the treatment wastewater W2 via the plurality of inflow pipes 21a to 21d, the distribution pipe 24, the valves 24a to 24d and the pump 24e for circulating the wastewater W1 and the treatment wastewater pipe 12. An open channel 25 for flowing to the sprinkling filter section 3.

また、固液分離部２は、ろ材充填層２２の逆洗浄機能を実行するための逆洗浄手段として、図２に示すように、排水槽２６と、複数の排水管２７ａ〜２７ｄ及び排水弁２８ａ〜２８ｄと、空気管２９とを備える。 As shown in FIG. 2, the solid-liquid separation unit 2 serves as a backwashing means for performing the backwashing function of the filter medium filling layer 22, and the drainage tank 26, the plurality of drainage pipes 27a to 27d, and the drainage valve 28a. 28d and the air pipe 29.

分配槽２０は、排水管１１から排水Ｗ１が供給され、固液分離接続管１８から膜濃縮水Ｗ５が供給される水槽である。図２の例では、固液分離接続管１８と排水管１１とが合流しているため、膜濃縮水Ｗ５が分配槽２０に返送されたときは、分配槽２０には、膜濃縮水Ｗ５が混合された排水Ｗ１が供給される。ただし、固液分離接続管１８と排水管１１とを合流させずに、分配槽２０内に排水Ｗ１と膜濃縮水Ｗ５とを別々に供給してもよい。 The distribution tank 20 is a water tank to which the drainage water W1 is supplied from the drainage pipe 11 and the membrane concentrated water W5 is supplied from the solid-liquid separation connecting pipe 18. In the example of FIG. 2, since the solid-liquid separation connecting pipe 18 and the drain pipe 11 merge, when the membrane concentrated water W5 is returned to the distribution tank 20, the membrane concentrated water W5 is stored in the distribution tank 20. The mixed wastewater W1 is supplied. However, the drainage W1 and the membrane concentrated water W5 may be separately supplied into the distribution tank 20 without joining the solid-liquid separation connecting pipe 18 and the drainage pipe 11.

分配槽２０は、ろ過水槽２１側と壁によって隔てられている。ろ過水槽２１は、固液分離処理（ろ過処理）を実行する前の（場合によっては、膜濃縮水Ｗ５が混合された）排水Ｗ１を貯留する水槽である。ろ過水槽２１は、ろ材充填層２２の下方に配置され、図２に示すように、流入配管２１ａ〜２１ｄ別に複数の水槽に分けられている。 The distribution tank 20 is separated from the filtered water tank 21 side by a wall. The filtered water tank 21 is a water tank that stores the wastewater W1 (in some cases, mixed with the membrane concentrated water W5) before performing the solid-liquid separation processing (filtration processing). The filtered water tank 21 is arranged below the filter medium filled layer 22, and is divided into a plurality of water tanks for each of the inflow pipes 21a to 21d, as shown in FIG.

複数の流入配管２１ａ〜２１ｄは、上述したろ過水槽２１における複数の水槽に各々排水Ｗ１を流入する管である。流入配管２１ａ〜２１ｄは、図２に示すように、ろ過水槽２１の各水槽に各々配置される。 The plurality of inflow pipes 21a to 21d are pipes for respectively inflowing the wastewater W1 into the plurality of water tanks in the above-described filtered water tank 21. As shown in FIG. 2, the inflow pipes 21 a to 21 d are arranged in each water tank of the filtered water tank 21.

ろ材充填層２２は、ろ過水槽２１に貯留された排水Ｗ１の固液分離処理を行うためのものである。具体的には、ろ材充填層２２は、ろ過水槽２１の各水槽の上方に配置され、８００ｍｍ以下、より好ましくは６００ｍｍ以下の層厚に形成される。このろ材充填層２２の内部には、複数の浮上ろ材（図示せず）が、排水Ｗ１中の固形成分を捕捉するに十分な細かさの空隙を形成する状態で充填されている。また、ろ材充填層２２の上面にはスクリーン２２ａが設置される。スクリーン２２ａは、液体成分を通すとともに、ろ材充填層２２内の浮上ろ材の流出を防止する。 The filter medium filled layer 22 is for performing solid-liquid separation processing of the wastewater W1 stored in the filtered water tank 21. Specifically, the filter medium filling layer 22 is arranged above each water tank of the filtered water tank 21, and is formed to have a layer thickness of 800 mm or less, more preferably 600 mm or less. A plurality of floating filter media (not shown) are filled in the filter media filling layer 22 in a state of forming voids having a fineness sufficient to capture solid components in the wastewater W1. A screen 22a is installed on the upper surface of the filter medium filling layer 22. The screen 22a allows the liquid component to pass through and prevents the floating filter medium in the filter medium filling layer 22 from flowing out.

ここで、ろ材充填層２２内の浮上ろ材としては、見掛け比重が０．１〜０．８であり、５０％圧縮硬さが０．１ＭＰａ以上であり、サイズが４〜１０ｍｍである材質のものが用いられる。見掛け比重が０．１未満であると望ましい圧縮強さを得ることができず、０．８を超えると水との比重差が小さくなって、ろ材充填層２２から流出するおそれがある。また、５０％圧縮硬さを０．１ＭＰａ以上としたのは、これよりも軟質であると、排水Ｗ１を高速な水流でろ過処理する際に圧密されてしまい、この結果、ＳＳ捕捉能力が低下するためである。さらに、サイズが４ｍｍ未満であると浮上ろ材相互間の間隙が小さくなって閉塞し易くなり、一方、サイズが１０ｍｍとなっても浮上ろ材によるＳＳ捕捉能力が低下するためである。 Here, as the floating filter medium in the filter medium filling layer 22, a material having an apparent specific gravity of 0.1 to 0.8, a 50% compression hardness of 0.1 MPa or more, and a size of 4 to 10 mm Is used. If the apparent specific gravity is less than 0.1, the desired compressive strength cannot be obtained, and if it exceeds 0.8, the difference in specific gravity with water becomes small, and there is a risk that it will flow out from the filter medium packed layer 22. Further, the reason why the 50% compression hardness is 0.1 MPa or more is that if it is softer than this, it will be compacted when filtering the wastewater W1 with a high-speed water flow, and as a result, the SS trapping ability will decrease. This is because Further, if the size is less than 4 mm, the gap between the floating filter materials becomes small, and it becomes easy to close it. On the other hand, even if the size is 10 mm, the SS trapping ability by the floating filter material decreases.

このような特性の浮上ろ材は、発泡ポリエチレン、発泡ポリスチレン、発泡ポリプロピレン等を用いて、製造することができる。また、浮上ろ材の形状は、風車形状又は十字形状等の凹凸のある形状とする。これによって、ろ材充填層２２に浮上ろ材を充填した時に、充填された各浮上ろ材の相互間に非直線的な間隙が形成され、この結果、各浮上ろ材によるＳＳ捕捉効果を高めることができる。なお、このろ材充填層２２のＳＳ捕捉効果を高めるためには、ろ材充填層２２の全容積に対する各浮上ろ材間の空隙容積の比率（すなわち、ろ材充填層２２の空隙率）を５０％程度に調整することが望ましい。ただし、浮上ろ材の形状及び材料は、以上説明したものに限られない。 The floating filter material having such characteristics can be manufactured by using expanded polyethylene, expanded polystyrene, expanded polypropylene, or the like. Further, the shape of the floating filter medium is a shape having irregularities such as a windmill shape or a cross shape. Thereby, when the filter medium filling layer 22 is filled with the floating filter medium, a non-linear gap is formed between the filled floating filter mediums, and as a result, the SS trapping effect of each floating filter medium can be enhanced. In order to enhance the SS trapping effect of the filter medium filled layer 22, the ratio of the void volume between the floating filter mediums to the total volume of the filter medium filled layer 22 (that is, the void ratio of the filter medium filled layer 22) is set to about 50%. It is desirable to adjust. However, the shape and material of the floating filter material are not limited to those described above.

共通ろ過水槽２３は、排水Ｗ１を固液分離処理して得られる処理用排水Ｗ２を貯留するためのものである。具体的には、共通ろ過水槽２３は、図２に示すように、ろ材充填層２２の上方に配置され、ろ過水槽２１の各水槽内の排水Ｗ１を各々固液分離処理して得られた各処理用排水Ｗ２を集める共通の水槽である。 The common filtered water tank 23 is for storing treatment wastewater W2 obtained by solid-liquid separation treatment of the wastewater W1. Specifically, as shown in FIG. 2, the common filtered water tank 23 is arranged above the filter medium filling layer 22, and each of the drainage water W1 in each water tank of the filtered water tank 21 is obtained by solid-liquid separation treatment. It is a common water tank that collects the treatment wastewater W2.

分配管２４、弁２４ａ〜２４ｄ及びポンプ２４ｅは、分配槽２０内の排水Ｗ１をろ過水槽２１の各水槽に分配するためのものである。具体的には、分配管２４は、分配槽２０と複数の流入配管２１ａ〜２１ｄとを連通する。弁２４ａ〜２４ｄは、分配管２４の各流水口近傍に各々配置され、ポンプ２４ｅは、この分配管２４内に配置される。分配管２４は、弁２４ａ〜２４ｄが開状態である際、ポンプ２４ｅの作用によって、分配槽２０から複数の流入配管２１ａ〜２１ｄに排水Ｗ１を分配流通させ、各流入配管２１ａ〜２１ｄを介して、ろ過水槽２１の各水槽に排水Ｗ１を各々流通させる。弁２４ａ〜２４ｄは、各々個別に開閉することができる。このため、弁２４ａ〜２４ｄの開閉によって、ろ過水槽２１の各水槽のうち、排水Ｗ１を流入したい水槽に排水Ｗ１を流入できる。なお、図２では、流入配管２１ｂ〜２１ｄの上部側の図示を省略しているが、流入配管２１ｂ〜２１ｄは、分配管２４と各々連通している。なお、分配槽２０内の排水Ｗ１を流入配管２１ａ〜２１ｄに自然流化させる構成とし、ポンプ２４ｅを省略してもよい。 The distribution pipe 24, the valves 24a to 24d, and the pump 24e are for distributing the wastewater W1 in the distribution tank 20 to each water tank of the filtered water tank 21. Specifically, the distribution pipe 24 connects the distribution tank 20 and the plurality of inflow pipes 21a to 21d. The valves 24a to 24d are arranged in the vicinity of the respective water outlets of the distribution pipe 24, and the pump 24e is arranged in the distribution pipe 24. When the valves 24a to 24d are in the open state, the distribution pipe 24 distributes the wastewater W1 from the distribution tank 20 to the plurality of inflow pipes 21a to 21d by the action of the pump 24e, and through the inflow pipes 21a to 21d. The waste water W1 is circulated in each of the water tanks of the filtered water tank 21. Each of the valves 24a to 24d can be opened and closed individually. Therefore, by opening and closing the valves 24a to 24d, the drainage W1 can flow into the water tank of the filtered water tank 21 to which the drainage W1 is desired to flow. In addition, in FIG. 2, although illustration of the upper side of the inflow pipes 21b to 21d is omitted, the inflow pipes 21b to 21d communicate with the distribution pipe 24, respectively. The pump 24e may be omitted by allowing the drainage water W1 in the distribution tank 20 to flow naturally into the inflow pipes 21a to 21d.

開水路２５は、共通ろ過水槽２３内の処理用排水Ｗ２を、処理用排水管１２を介して、固液分離部２の後段に位置する散水ろ床部３（図１参照）に流通させるためのものである。具体的には、開水路２５は、上部側が開口している水路である。また、開水路２５には、処理用排水管１２が接続されている。開水路２５は、処理用排水管１２を介して、共通ろ過水槽２３と図１に示した散水ろ床部３とを連通する。開水路２５は、共通ろ過水槽２３から自然流下してきた処理用排水Ｗ２を受け入れ、処理用排水管１２を介して、受け入れた処理用排水Ｗ２を散水ろ床部３へ自然流下させる。なお、ポンプを使用して、処理用排水Ｗ２を散水ろ床部３へ送水してもよい。 The open water channel 25 allows the processing wastewater W2 in the common filtered water tank 23 to flow through the processing drainage pipe 12 to the sprinkling filter section 3 (see FIG. 1) located at the subsequent stage of the solid-liquid separation section 2. belongs to. Specifically, the open water channel 25 is a water channel whose upper side is open. Further, the treatment drainage pipe 12 is connected to the open water passage 25. The open channel 25 connects the common filtered water tank 23 and the sprinkling filter section 3 shown in FIG. 1 via the treatment drainage pipe 12. The open water channel 25 receives the treatment wastewater W2 that has naturally flown from the common filtered water tank 23, and causes the received treatment wastewater W2 to naturally flow to the sprinkling filter section 3 via the treatment drain pipe 12. In addition, you may send a process wastewater W2 to the sprinkling filter part 3 using a pump.

排水槽２６、複数の排水管２７ａ〜２７ｄ、排水弁２８ａ〜２８ｄ及び空気管２９は、上述したように、固液分離装置２におけるろ材充填層２２の逆洗浄機能を実行するための逆洗浄手段を構成する。具体的には、排水槽２６は、ろ材充填層２２を逆洗浄した後の洗浄済み液体（以下、逆洗排水という）を貯留する。排水管２７ａ〜２７ｄは、ろ過水槽２１の各水槽と排水槽２６とを各々連通する。排水弁２８ａ〜２８ｄは、排水管２７ａ〜２７ｄに各々配置され、各排水管２７ａ〜２７ｄを開閉する。空気管２９は、ろ材充填層２２の逆洗浄に寄与する空気をろ材充填層２２内に噴出する。固液分離部２は、以上説明したように材充填層２２の逆洗浄機能を実行するが、ろ材充填層２２を逆洗浄する構成は、これに限られず、任意の構成及び方法を採ることができる。 The drainage tank 26, the plurality of drainage pipes 27a to 27d, the drainage valves 28a to 28d, and the air pipe 29 are, as described above, the backwashing means for performing the backwashing function of the filter medium packed layer 22 in the solid-liquid separation device 2. Make up. Specifically, the drainage tank 26 stores the washed liquid (hereinafter referred to as backwash drainage) after backwashing the filter medium filling layer 22. The drain pipes 27a to 27d connect the water tanks of the filtered water tank 21 and the drain tank 26, respectively. The drainage valves 28a to 28d are arranged in the drainage pipes 27a to 27d, respectively, and open and close the drainage pipes 27a to 27d. The air pipe 29 ejects air, which contributes to the backwashing of the filter medium packed layer 22, into the filter medium packed layer 22. The solid-liquid separation unit 2 performs the back-cleaning function of the material-filled layer 22 as described above, but the structure for back-cleaning the filter-material packed layer 22 is not limited to this, and any structure and method may be adopted. it can.

つぎに、図２の実線矢印に示される排水Ｗ１又は処理用排水Ｗ２の流れを参照しつつ、固液分離部２による排水Ｗ１の固液分離処理について説明する。排水Ｗ１は、まず、生活排水又は工場排水等の外部からの汚水として、分配槽２０に流入される。この場合、排水Ｗ１は、ポンプ等の動力を用いて強制的に流入してもよいし、自然流によって流入してもよい。 Next, the solid-liquid separation processing of the waste water W1 by the solid-liquid separation unit 2 will be described with reference to the flow of the waste water W1 or the processing waste water W2 indicated by the solid arrow in FIG. The wastewater W1 first flows into the distribution tank 20 as sewage from the outside such as domestic wastewater or factory wastewater. In this case, the drainage W1 may be forced to flow in by using power of a pump or the like, or may be flowed in by a natural flow.

分配槽２０に貯留された排水Ｗ１は、分配管２４内を流通して各流入配管２１ａ〜２１ｄに各々分配される。つぎに、流入配管２１ａ〜２１ｄ内の各排水Ｗ１は、自然流下してろ過水槽２１に流入し、その後、図２の実線矢印に示すように、ろ過水槽２１の各水槽に各々流入する。 The wastewater W1 stored in the distribution tank 20 flows through the distribution pipe 24 and is distributed to the respective inflow pipes 21a to 21d. Next, each drainage W1 in the inflow pipes 21a to 21d naturally flows down and flows into the filtered water tank 21, and then flows into each water tank of the filtered water tank 21 as shown by a solid arrow in FIG.

ろ過水槽２１の各水槽内の排水Ｗ１は、上向きの流れでろ材充填層２２を通過する。この場合、各水槽内の排水Ｗ１は、図２の実線矢印に示すように、ろ材充填層２２の下部から上部に向かってろ材充填層２２内を通過する間に、ろ材充填層２２によってろ過処理される。すなわち、ろ材充填層２２は、上述した内部の各浮上ろ材によって、これら各浮上ろ材間の空隙内を通過中の上向流の排水Ｗ１に含まれる夾雑物、ＳＳ及び固形性ＢＯＤ等の各種固形成分を漏れなく捕捉して、この上向流の排水Ｗ１を固形成分と処理用排水Ｗ２とに分離する。このようにして、固液分離部２による排水Ｗ１の固液分離処理が達成される。なお、上述したろ材充填層２２による排水Ｗ１のろ過速度は、分配槽２０への排水Ｗ１の流入水量に対応して調整され、これによって、排水Ｗ１の高速ろ過処理が可能になる。この結果、固液分離部２は、排水Ｗ１に対して高効率の固液分離処理を行うことができる。 The drainage W1 in each water tank of the filtered water tank 21 passes through the filter medium filling layer 22 in an upward flow. In this case, the wastewater W1 in each water tank is filtered by the filter medium filling layer 22 while passing through the filter medium filling layer 22 from the lower part to the upper part of the filter medium filling layer 22 as shown by the solid line arrow in FIG. To be done. That is, the filter medium-filled layer 22 is made of various solid substances such as contaminants, SS and solid BOD contained in the upward flow wastewater W1 passing through the voids between the floating filter media by the above-mentioned respective floating filter media. The components are captured without leakage, and the upward flow wastewater W1 is separated into solid components and processing wastewater W2. In this way, the solid-liquid separation processing of the wastewater W1 by the solid-liquid separation unit 2 is achieved. The filtration rate of the wastewater W1 by the above-described filter medium filled layer 22 is adjusted in accordance with the amount of the inflow water of the wastewater W1 into the distribution tank 20, which enables high-speed filtration of the wastewater W1. As a result, the solid-liquid separation unit 2 can perform highly efficient solid-liquid separation processing on the wastewater W1.

上述した固液分離処理によって得られた処理用排水Ｗ２は、スクリーン２２ａを通過して共通ろ過水槽２３内に流入（合流）する。その後、処理用排水Ｗ２は、図２の実線矢印に示すように、開水路２５内に流入して、共通ろ過水槽２３から、処理用排水管１２を介して、散水ろ床部３へ流れる。 The treatment wastewater W2 obtained by the solid-liquid separation treatment described above passes through the screen 22a and flows (merges) into the common filtered water tank 23. After that, the treatment wastewater W2 flows into the open channel 25 and flows from the common filtered water tank 23 to the sprinkling filter section 3 via the treatment drain pipe 12 as shown by the solid arrow in FIG.

（散水ろ床部について）
次に、図１に示した散水ろ床部３について詳細に説明する。ここでは、まず、散水ろ床部３の構成について説明し、その後、散水ろ床部３による処理用排水Ｗ２の生物処理（ろ過処理）について説明する。 (About sprinkling filter floor)
Next, the sprinkling filter part 3 shown in FIG. 1 will be described in detail. Here, first, the configuration of the sprinkling filter part 3 will be described, and then the biological treatment (filtering process) of the treatment wastewater W2 by the sprinkling filter part 3 will be described.

図３は、第１実施形態に係る排水処理システムの散水ろ床部の一構成例を示す模式図である。図３に示すように、この散水ろ床部３は、微生物を付着したろ材が充填されたろ材充填層を内包するろ床本体３０と、固液分離装置２によって得られた処理用排水Ｗ２をろ床本体３０の内部に散布する回転式散水装置３１とを有する。また、図３には特に図示しないが、散水ろ床部３は、ろ床本体３０内のろ材充填層を洗浄する洗浄機能を実行するための洗浄手段を備える。また、ろ床本体３０には、処理水管１３が接続されている。 FIG. 3 is a schematic diagram showing a configuration example of the sprinkling filter section of the wastewater treatment system according to the first embodiment. As shown in FIG. 3, the sprinkling filter unit 3 includes a filter bed body 30 that contains a filter medium-filled layer filled with a filter medium to which microorganisms are attached, and a treatment wastewater W2 obtained by the solid-liquid separation device 2. It has a rotary sprinkler 31 for spraying inside the filter bed body 30. Although not particularly shown in FIG. 3, the sprinkling filter part 3 includes a cleaning means for performing a cleaning function of cleaning the filter medium filling layer in the filter bed body 30. A treated water pipe 13 is connected to the filter bed body 30.

ろ床本体３０は、表面に微生物を付着した複数のろ材が充填された槽であり、図３に示すように、６つの処理水槽３０ａ〜３０ｆを組み合わせて構成される。処理水槽３０ａ〜３０ｆの各々は、ろ材充填層内の微生物によって処理用排水Ｗ２を生物処理して浄化する水処理機能と、このろ材充填層を洗浄する洗浄機能とを備える。なお、これら処理水槽３０ａ〜３０ｆの構成の詳細については、後述する。 The filter bed main body 30 is a tank filled with a plurality of filter media having microorganisms attached to the surface thereof, and is configured by combining six treated water tanks 30a to 30f as shown in FIG. Each of the treated water tanks 30a to 30f has a water treatment function of biologically treating and purifying the treatment wastewater W2 by the microorganisms in the filter medium packed layer, and a cleaning function of cleaning the filter medium packed layer. The details of the configurations of the treated water tanks 30a to 30f will be described later.

回転式散水装置３１は、上述した固液分離装置２から流出された処理用排水Ｗ２をろ床本体３０の処理水槽３０ａ〜３０ｆの各内部に散布するためのものである。具体的には、回転式散水装置３１は、処理用排水管１２及び散水ろ床接続管１７と連通するように配管されている。回転式散水装置３１は、処理用排水管１２から処理用排水Ｗ２が供給され、散水ろ床接続管１７から膜濃縮水Ｗ５が供給される。処理用排水管１２と散水ろ床接続管１７とは合流しているため、回転式散水装置３１には、膜濃縮水Ｗ５が混合された処理用排水Ｗ２が供給されるということができる。ただし、処理用排水管１２と散水ろ床接続管１７とは合流していなくてもよく、回転式散水装置３１に、処理用排水Ｗ２と膜濃縮水Ｗ５とが別々に供給されてもよい。 The rotary water sprinkler 31 is for spraying the treatment wastewater W2 that has flowed out from the solid-liquid separator 2 described above into each of the treatment water tanks 30a to 30f of the filter bed body 30. Specifically, the rotary sprinkler device 31 is arranged so as to communicate with the treatment drain pipe 12 and the sprinkling filter connection pipe 17. The rotary sprinkler 31 is supplied with the treatment wastewater W2 from the treatment drainage pipe 12 and is supplied with the membrane concentrated water W5 from the sprinkling filter connection pipe 17. Since the treatment drainage pipe 12 and the sprinkling filter connection pipe 17 merge, it can be said that the rotary sprinkler 31 is supplied with the treatment wastewater W2 mixed with the membrane concentrated water W5. However, the treatment drainage pipe 12 and the sprinkling filter connection pipe 17 may not be joined, and the treatment drainage W2 and the membrane concentrated water W5 may be separately supplied to the rotary water sprinkler 31.

この回転式散水装置３１の配管は、処理用排水管１２及び散水ろ床接続管１７から、図３に示すようにろ床本体３０の内部を通り、ろ床本体３０の中心部Ｃにおいて上向きに延伸してろ床本体３０の上部に露出している。また、この配管の端部には、水流によってろ床本体３０の円周方向に回転する回転機構が設けられる。ろ床本体３０の上部には、この回転機構からろ床本体３０の円周部Ａに向けて放射状に、複数（例えば３つ）の散水ノズルが設けられる。これら複数の散水ノズルの各々は、この回転式散水装置３１の配管と連通し、この回転機構の作用によって、ろ床本体３０の円周方向に回転する。なお、回転式散水装置３１の散水ノズルの数は、３つ（図３参照）に限定されず、１つでもよいし、複数でもよい。このような回転式散水装置３１は、配管を介して固液分離部２から処理用排水Ｗ２を受け入れ、処理用排水Ｗ２の流れによって回転機構とともに各散水ノズルを回転させる。回転式散水装置３１は、このように回転する各散水ノズルの散水口から、処理水槽３０ａ〜３０ｆ内の各ろ材充填層上面に処理用排水Ｗ２を一様に散布する。 The piping of the rotary water sprinkler 31 passes through the inside of the filter bed main body 30 from the treatment drain pipe 12 and the water sprinkling filter connection pipe 17 as shown in FIG. It is extended and exposed at the upper part of the filter bed body 30. In addition, a rotating mechanism that rotates in the circumferential direction of the filter bed body 30 by a water flow is provided at the end of this pipe. A plurality of (for example, three) sprinkling nozzles are provided on the upper part of the filter bed main body 30 radially from the rotating mechanism toward the circumferential portion A of the filter bed main body 30. Each of the plurality of sprinkler nozzles communicates with the pipe of the rotary sprinkler 31 and rotates in the circumferential direction of the filter bed body 30 by the action of this rotating mechanism. The number of water spray nozzles of the rotary water sprinkler 31 is not limited to three (see FIG. 3), and may be one or plural. The rotary water sprinkler 31 receives the treatment wastewater W2 from the solid-liquid separation unit 2 through the pipe and rotates the sprinkler nozzles together with the rotating mechanism by the flow of the treatment wastewater W2. The rotary water sprinkler 31 uniformly sprays the treatment wastewater W2 on the upper surfaces of the filter medium-filled layers in the treated water tanks 30a to 30f from the water sprinkling openings of the respective sprinkling nozzles.

処理水管１３は、ろ床本体３０の処理水槽３０ａ〜３０ｆによって処理用排水Ｗ２を生物処理して得た処理水Ｗ３を、散水ろ床部３の後段に位置する膜ろ過部４（図１参照）に流通させるためのものである。具体的には、処理水管１３は、ろ床本体３０の下層、すなわち、処理水槽３０ａ〜３０ｆの各下層と膜ろ過部４とを連通する。処理水管１３は、自然流下又はポンプ等の作用によって、処理水槽３０ａ〜３０ｆの各下層から膜ろ過部４へ処理水Ｗ３を流通させる。 The treated water pipe 13 uses the treated water W3 obtained by biologically treating the treated wastewater W2 by the treated water tanks 30a to 30f of the filter bed body 30, and the membrane filtration unit 4 (see FIG. 1) located after the sprinkling filter unit 3 ) Is intended for distribution. Specifically, the treated water pipe 13 connects the lower layer of the filter bed body 30, that is, each lower layer of the treated water tanks 30a to 30f to the membrane filtration unit 4. The treated water pipe 13 allows the treated water W3 to flow from the lower layers of the treated water tanks 30a to 30f to the membrane filtration unit 4 by natural flow or by the action of a pump or the like.

つぎに、上述した処理水槽３０ａ〜３０ｆの構成について詳細に説明する。なお、処理水槽３０ａ〜３０ｆの各構成は互いに同様であるため、以下では、処理水槽３０ａの構成を代表して説明する。 Next, the configurations of the above-mentioned treated water tanks 30a to 30f will be described in detail. Since the configurations of the treated water tanks 30a to 30f are similar to each other, the configuration of the treated water tank 30a will be described below as a representative.

図４は、第１実施形態に係る散水ろ床部の処理水槽の一構成例を示す模式図である。図４に示すように、処理水槽３０ａは、微生物を付着したろ材３５が充填されたろ材充填層３３ｂと、処理水管１３（図３参照）と処理水槽３０ａの内部とを連通する流通管３４ａと、ろ材３５の流出を防止するろ材流出防止網３３ｄとを備える。また、処理水槽３０ａは、ろ材充填層３３ｂの洗浄機能を実行するための洗浄手段として、弁３４ｂ，３９ｂと、送風装置３７ａと、空気噴出管３７ｂと、邪魔板３８と、洗浄排水管３９ａとを備える。 FIG. 4 is a schematic diagram showing a configuration example of a treated water tank of the water sprinkling filter section according to the first embodiment. As shown in FIG. 4, the treated water tank 30a includes a filter medium packed layer 33b filled with a filter medium 35 having microorganisms attached thereto, a treated water pipe 13 (see FIG. 3), and a distribution pipe 34a that communicates the inside of the treated water tank 30a. And a filter medium outflow prevention net 33d for preventing the filter medium 35 from flowing out. Further, the treated water tank 30a serves as a cleaning unit for performing the cleaning function of the filter medium filling layer 33b, the valves 34b and 39b, the air blower 37a, the air ejection pipe 37b, the baffle plate 38, and the cleaning drain pipe 39a. Equipped with.

処理水槽３０ａは、表面に微生物を付着したろ材３５が充填された槽であり、ろ材充填層３３ｂと、ろ材充填層３３ｂの上層３３ａと下層３３ｃとに区分けされる。処理水槽３０ａの上層３３ａ側は開口しており、この開口によって外部と処理水槽３０ａ内部との通気が可能となっている。また、処理水槽３０ａの上層３３ａ側には回転式散水装置３１の散水ノズルが位置し、処理水槽３０ａの下層３３ｃ側は、流通管３４ａ及び洗浄排水管３９ａと連通している。 The treated water tank 30a is a tank filled with a filter medium 35 having microorganisms attached to its surface, and is divided into a filter medium packed layer 33b and an upper layer 33a and a lower layer 33c of the filter medium packed layer 33b. The upper layer 33a side of the treated water tank 30a is open, and this opening allows ventilation between the outside and the inside of the treated water tank 30a. The sprinkler nozzle of the rotary water sprinkler 31 is located on the upper layer 33a side of the treated water tank 30a, and the lower layer 33c side of the treated water tank 30a is in communication with the flow pipe 34a and the cleaning drain pipe 39a.

ろ材充填層３３ｂは、固液分離部２によって得られた処理用排水Ｗ２の生物処理を行うためのものである。ろ材充填層３３ｂには、上層３３ａ側から下層３３ｃ側に向けて処理用排水Ｗ２が自然流下できる程度の空隙を形成するように、複数のろ材３５が充填される。ろ材流出防止網３３ｄは、ろ材充填層３３ｂに配置され、ろ材充填層３３ｂ内の複数のろ材３５を支持する。また、ろ材流出防止網３３ｄは、液体成分を通すとともに、ろ材充填層３３ｂから下層３３ｃへのろ材３５の流出を防止する。なお、ろ材充填層３３ｂによって処理用排水Ｗ２を生物処理して得られた処理水Ｗ３は、このろ材流出防止網３３ｄを通り、ろ材充填層３３ｂの下面側から自然流下して、処理水槽３０ａの下層３３ｃに流れる。 The filter medium filled layer 33b is for performing biological treatment of the treatment wastewater W2 obtained by the solid-liquid separation unit 2. The filter medium filling layer 33b is filled with a plurality of filter mediums 35 so as to form a gap from the upper layer 33a side to the lower layer 33c side so that the treatment wastewater W2 can flow down naturally. The filter medium outflow prevention net 33d is arranged in the filter medium filling layer 33b and supports the plurality of filter media 35 in the filter medium filling layer 33b. Further, the filter medium outflow prevention net 33d allows the liquid component to pass therethrough, and also prevents the filter medium 35 from flowing out from the filter medium filled layer 33b to the lower layer 33c. The treated water W3 obtained by biologically treating the treatment wastewater W2 with the filter medium filling layer 33b passes through the filter medium outflow prevention net 33d, and naturally flows down from the lower surface side of the filter medium filling layer 33b to obtain the treated water tank 30a. It flows to the lower layer 33c.

ここで、ろ材３５は、ポリウレタン又はポリプロピレン等の物質の表面に微生物を付着させたものであり、その比重は、水の比重（＝１．０）に近似する値、例えば０．９である。また、ろ材３５は、例えば図４に示すように円筒形状に形成された円筒形ろ材である。ろ材３５の円筒内外の各表面状態は、平滑であってもよいが、処理用排水Ｗ２に対する接触面積の増大に有効な表面状態、例えば、微細な凹凸状態、蛇腹状態、又は、これらを組み合わせた状態であることが望ましい。このような円筒形状のろ材３５が充填されたろ材充填層３３ｂにおいて、各ろ材３５の相互間に非直線的な空隙が形成され、且つ、各ろ材３５の円筒中空部分によって空隙が形成される。この場合、ろ材充填層３３ｂの全容積に対する各ろ材３５による空隙容積の比率、すなわち、ろ材充填層３３ｂの空隙率は、例えば９０％程度になる。ろ材３５の外壁面及び内壁面は、これら空隙内を流下する処理用排水Ｗ２と接触することになり、これによって、ろ材３５と処理用排水Ｗ２との接触面積が十分に大きくなる。この結果、ろ材充填層３３ｂ（各ろ材３５）による処理用排水Ｗ２の生物処理能力は、処理水槽３０ａに対して要望される必要レベル以上に向上する。ただし、ろ材３５の形状及び材料は、これに限られず、表面に微生物を付着できるものであればよい。また、ろ材３５に付着する微生物は、処理用排水Ｗ２に含まれる有機物を分解するＢＯＤ（Biochemical oxygen demand）酸化菌や、アンモニア性窒素を分解する硝化菌などであるが、処理用排水Ｗ２に含まれる有機物などの汚濁物質を生物処理するものであれば、これに限られない。 Here, the filter medium 35 is made by attaching microorganisms to the surface of a substance such as polyurethane or polypropylene, and its specific gravity is a value close to the specific gravity of water (=1.0), for example, 0.9. The filter medium 35 is, for example, a cylindrical filter medium formed in a cylindrical shape as shown in FIG. Each surface state inside and outside the cylinder of the filter medium 35 may be smooth, but a surface state effective for increasing the contact area with the treatment wastewater W2, for example, a fine uneven state, a bellows state, or a combination thereof. It is desirable to be in a state. In the filter medium filling layer 33b filled with such a cylindrical filter medium 35, non-linear voids are formed between the filter mediums 35, and voids are formed by the hollow cylindrical portions of the filter mediums 35. In this case, the ratio of the void volume of each filter medium 35 to the total volume of the filter medium filled layer 33b, that is, the void ratio of the filter medium filled layer 33b is, for example, about 90%. The outer wall surface and the inner wall surface of the filter medium 35 come into contact with the treatment wastewater W2 flowing down in these voids, whereby the contact area between the filter medium 35 and the treatment wastewater W2 becomes sufficiently large. As a result, the biological treatment capacity of the treatment wastewater W2 by the filter medium filling layer 33b (each filter medium 35) is improved to the required level or more required for the treated water tank 30a. However, the shape and material of the filter medium 35 are not limited to this, and may be any as long as microorganisms can adhere to the surface. The microorganisms attached to the filter medium 35 include BOD (Biochemical oxygen demand) oxidizing bacteria that decompose organic matter contained in the treatment wastewater W2 and nitrifying bacteria that decompose ammonia nitrogen, but are included in the treatment wastewater W2. It is not limited to this as long as it is a biological treatment of pollutants such as organic substances.

弁３４ｂ，３９ｂ、送風装置３７ａ、空気噴出管３７ｂ、邪魔板３８、及び洗浄排水管３９ａは、処理水槽３０ａにおけるろ材充填層３３ｂの洗浄機能を実行するための洗浄手段を構成する。弁３４ｂは、処理水槽３０ａ内に洗浄液を流入してろ材充填層３３ｂの洗浄機能を発揮させる期間、流通管３４ａの開口を閉じて、膜ろ過部４への処理水Ｗ３の流通を遮断する。 The valves 34b and 39b, the air blower 37a, the air ejection pipe 37b, the baffle plate 38, and the cleaning drain pipe 39a constitute a cleaning means for performing the cleaning function of the filter medium filling layer 33b in the treated water tank 30a. The valve 34b closes the opening of the flow pipe 34a and shuts off the flow of the treated water W3 to the membrane filtration unit 4 during a period in which the cleaning liquid flows into the treated water tank 30a to exert the cleaning function of the filter medium filling layer 33b.

送風装置３７ａは、ろ材充填層３３ｂ内の各ろ材３５の洗浄に必要な空気を空気噴出管３７ｂに送給する。空気噴出管３７ｂは、処理水槽３０ａ内の少なくともろ材充填層３３ｂを冠水させた洗浄液に空気を噴出して、ろ材充填層３３ｂ内の各ろ材３５を撹拌洗浄する旋回流を、この洗浄液に発生させる。具体的には、空気噴出管３７ｂは、図４に示すように処理水槽３０ａの下層３３ｃに配置される。空気噴出管３７ｂは、処理水槽３０ａの中心壁３６ａの近傍且つ下層３３ｃから、ろ材充填層３３ｂに向けて、送風装置３７ａからの空気を噴出して、この洗浄液の上下方向の旋回流を発生させる。なお、ろ材充填層３３ｂは、図３に示したろ床本体３０を代表する処理水槽３０ａ内の層であり、散水ろ床部３内のろ材充填層の一つに他ならない。 The air blower 37a sends the air required for cleaning each filter medium 35 in the filter medium packed layer 33b to the air ejection pipe 37b. The air jet pipe 37b jets air into the cleaning liquid that has submerged at least the filter medium filling layer 33b in the treated water tank 30a to generate a swirling flow for stirring and cleaning each filter medium 35 in the filter medium filling layer 33b in this cleaning liquid. .. Specifically, the air ejection pipe 37b is arranged in the lower layer 33c of the treated water tank 30a as shown in FIG. The air ejection pipe 37b ejects the air from the blower 37a toward the filter medium filling layer 33b from the lower layer 33c in the vicinity of the center wall 36a of the treated water tank 30a to generate a vertical swirling flow of the cleaning liquid. .. The filter medium filling layer 33b is a layer in the treated water tank 30a that is representative of the filter bed body 30 shown in FIG. 3, and is one of the filter medium filling layers in the sprinkling filter unit 3.

邪魔板３８は、図４に示すように、処理水槽３０ａの中心壁３６ａ側の領域と円周壁３６ｂ側の領域とに処理水槽３０ａの槽内領域を仕切る仕切板である。なお、中心壁３６ａは、処理水槽３０ａの側壁のうちの、図３に示したろ床本体３０の中心部Ｃ側の側壁である。円周壁３６ｂは、処理水槽３０ａの側壁のうちの、ろ床本体３０の円周部Ａ側の側壁である。邪魔板３８は、図４に示すように、中心壁３６ａよりも円周壁３６ｂ（すなわちろ床本体３０の外壁側）に近い位置に設けられ、上述したように処理水槽３０ａの槽内領域を仕切る。このようにして、邪魔板３８は、空気噴出管３７ｂから空気が噴出される領域（以下、中心側領域という）と、空気が噴出されない領域（以下、円周側領域という）とに、処理水槽３０ａの槽内領域を仕切る。このような邪魔板３８は、処理水槽３０ａ内に貯留した洗浄液へ空気噴出管３７ｂから空気を噴出することによって発生した洗浄液流の一部を邪魔し、これによって、この洗浄液の旋回流（具体的には上下方向の旋回流）の発生を促進する。なお、処理水槽３０ａ内の中心側領域は散水ろ床部３内における空気の噴出領域であり、処理水槽３０ａ内の円周側領域は散水ろ床部３内における空気の非噴出領域である。すなわち、邪魔板３８は、散水ろ床３内を噴出領域と非噴出領域とに仕切って、洗浄液の旋回流の発生を促進する仕切板の一つに他ならない。 As shown in FIG. 4, the baffle plate 38 is a partition plate for partitioning the inner region of the treated water tank 30a into a region on the side of the central wall 36a and a region on the side of the circumferential wall 36b of the treated water tank 30a. The center wall 36a is a side wall of the treated water tank 30a on the center portion C side of the filter bed body 30 shown in FIG. The circumferential wall 36b is a sidewall on the circumferential portion A side of the filter bed body 30 among the sidewalls of the treated water tank 30a. As shown in FIG. 4, the baffle plate 38 is provided at a position closer to the circumferential wall 36b (that is, the outer wall side of the filter bed body 30) than the center wall 36a, and partitions the inner region of the treated water tank 30a as described above. .. In this way, the baffle plate 38 has a treatment water tank in a region where air is ejected from the air ejection pipe 37b (hereinafter referred to as a center side region) and a region where air is not ejected (hereinafter referred to as a circumferential side region). The area in the tank 30a is partitioned. Such a baffle plate 38 obstructs a part of the cleaning liquid flow generated by ejecting air from the air ejection pipe 37b to the cleaning liquid stored in the treated water tank 30a, and thereby the swirling flow of the cleaning liquid (specifically, The vertical swirling flow) is promoted. The central region of the treated water tank 30a is an air ejection region in the sprinkling filter part 3, and the circumferential region of the treated water tank 30a is a non-ejection region of air in the sprinkling filter part 3. That is, the baffle plate 38 is none other than a partition plate that partitions the inside of the sprinkling filter bed 3 into a jet area and a non-jet area and promotes the generation of the swirling flow of the cleaning liquid.

洗浄排水管３９ａは、各ろ材３５の撹拌洗浄後の洗浄液を排出する。弁３９ｂは、この洗浄排水管３９ａを開閉するための弁である。洗浄排水管３９ａは、弁３９ｂによって開放された期間、処理水槽３０ａの下層３３ｃから、上述した洗浄液の旋回流によって各ろ材３５を撹拌洗浄した後の洗浄液を外部に排出する。散水ろ床部３は、以上説明したようにろ材充填層３３ｂの洗浄機能を実行する（逆洗浄を行う）が、ろ材充填層３３ｂを洗浄する構成は、これに限られない。 The cleaning drain pipe 39a discharges the cleaning liquid after the stirring cleaning of each filter medium 35. The valve 39b is a valve for opening and closing the cleaning drainage pipe 39a. The cleaning drainage pipe 39a discharges the cleaning liquid after stirring and cleaning the respective filter media 35 from the lower layer 33c of the treated water tank 30a by the swirling flow of the cleaning liquid, while being opened by the valve 39b. Although the sprinkling filter unit 3 performs the cleaning function of the filter medium filling layer 33b (performs reverse cleaning) as described above, the configuration for cleaning the filter medium filling layer 33b is not limited to this.

つぎに、図４の矢印に示される処理用排水Ｗ２又は処理水Ｗ３の流れを参照しつつ、処理水槽３０ａによる処理用排水Ｗ２の生物処理について説明する。処理用排水Ｗ２は、上述した固液分離部２から回転式散水装置３１の管内を流通して、処理水槽３０ａ内に流入される。この場合、処理用排水Ｗ２は、回転式散水装置３１の各散水ノズルから自然流下して、ろ材充填層３３ｂの上面に散布される。 Next, the biological treatment of the treatment wastewater W2 by the treatment water tank 30a will be described with reference to the flow of the treatment wastewater W2 or the treatment water W3 shown by the arrow in FIG. The treatment wastewater W2 flows through the pipe of the rotary water sprinkler 31 from the solid-liquid separation unit 2 described above, and flows into the treatment water tank 30a. In this case, the treatment wastewater W2 naturally flows down from the sprinkling nozzles of the rotary sprinkler 31 and is sprinkled on the upper surface of the filter medium filling layer 33b.

ろ材充填層３３ｂの上面に散布された処理用排水Ｗ２は、ろ材充填層３３ｂの通気とともに自然流下して、ろ材充填層３３ｂを通過する。例えば、図４の波線矢印に示されるように、回転式散水装置３１から散布された処理用排水Ｗ２は、各ろ材３５の表面と順次接触しつつ自然流下する。このろ材３５と処理用排水Ｗ２との接触時に、ろ材３５表面の微生物が、処理用排水Ｗ２中の有機物などの汚濁物質を分解処理する。 The treatment wastewater W2 scattered on the upper surface of the filter medium filling layer 33b naturally flows down along with the ventilation of the filter medium filling layer 33b, and passes through the filter medium filling layer 33b. For example, as indicated by the broken line arrow in FIG. 4, the treatment wastewater W2 sprayed from the rotary water sprinkler 31 naturally flows down while sequentially contacting the surfaces of the filter media 35. At the time of contact between the filter medium 35 and the treatment wastewater W2, microorganisms on the surface of the filter medium 35 decompose the pollutants such as organic substances in the treatment wastewater W2.

このように、ろ材充填層３３ｂ内を流下中の処理用排水Ｗ２は、ろ材３５と接触する毎に微生物によって生物処理され続け、この結果、有機物などの汚濁物質が分解除去された処理水Ｗ３として、ろ材流出防止網３３ｄから処理水槽３０ａの下層３３ｃに流下する。このようにして、処理水槽３０ａによる処理用排水Ｗ２の生物処理が達成される。 In this way, the treatment wastewater W2 flowing down in the filter medium packed layer 33b is continuously biologically treated by the microorganisms every time it comes into contact with the filter medium 35, and as a result, the treated water W3 is obtained by decomposing and removing pollutants such as organic substances. Then, it flows down from the filter material outflow prevention net 33d to the lower layer 33c of the treated water tank 30a. In this way, biological treatment of the treatment wastewater W2 by the treated water tank 30a is achieved.

上述した生物処理によって得られた処理水Ｗ３は、弁３４ｂを介して、処理水槽３０ａの下層３３ｃから流通管３４ａに流出し、その後、流通管３４ａを通じて処理水管１３（図３参照）に流通し、処理水管１３から膜ろ過部４へ流れる。この場合、弁３４ｂは開いた状態であるため、処理水Ｗ３は、下層３３ｃに流下した後、直ちに流通管３４ａ内に流れる。このため、上述した生物処理の実行時に、処理水Ｗ３がろ材充填層３３ｂの上面の高さまで溜まることは、あり得ない。 The treated water W3 obtained by the biological treatment described above flows out from the lower layer 33c of the treated water tank 30a into the distribution pipe 34a through the valve 34b, and then flows into the treated water pipe 13 (see FIG. 3) through the distribution pipe 34a. , From the treated water pipe 13 to the membrane filtration unit 4. In this case, since the valve 34b is in the open state, the treated water W3 flows into the distribution pipe 34a immediately after flowing down to the lower layer 33c. Therefore, it is impossible that the treated water W3 accumulates up to the height of the upper surface of the filter medium filling layer 33b when the biological treatment is performed.

なお、図３に示したろ床本体３０の処理水槽３０ｂ〜３０ｆによる処理用排水Ｗ２の水処理機能は、上述した処理水槽３０ａの場合と同様である。すなわち、処理水槽３０ｂ〜３０ｆの各々は、回転式散水装置３１の各散水ノズルからろ材充填層上面に散布された処理用排水Ｗ２を、処理水槽３０ａと同様に各ろ材３５表面の微生物によって生物処理し、これによって得られた処理水Ｗ３を、処理水管１３等を通じて膜ろ過部４へ送出する。 The water treatment function of the treated wastewater W2 by the treated water tanks 30b to 30f of the filter bed body 30 shown in FIG. 3 is similar to that of the treated water tank 30a described above. That is, in each of the treated water tanks 30b to 30f, the treatment wastewater W2 sprayed from the sprinkling nozzles of the rotary water sprinkler 31 to the upper surface of the filter medium filling layer is biologically treated by the microorganisms on the surface of each filter medium 35 as in the treated water tank 30a. Then, the treated water W3 thus obtained is sent to the membrane filtration unit 4 through the treated water pipe 13 and the like.

（膜ろ過部について）
次に、図１に示した膜ろ過部４について詳細に説明する。まず、膜ろ過部４の構成について説明し、その後、膜ろ過部４による処理水Ｗ３の固液分離処理について説明する。 (About the membrane filtration section)
Next, the membrane filtration unit 4 shown in FIG. 1 will be described in detail. First, the configuration of the membrane filtration unit 4 will be described, and then the solid-liquid separation treatment of the treated water W3 by the membrane filtration unit 4 will be described.

図５は、第１実施形態に係る膜ろ過部の一構成例を示す模式図である。図５に示すように、膜ろ過部４は、ろ過水槽４０と、複数のろ過膜４２ａ、４２ｂ、４２ｃとを有する。なお、本実施形態では、ろ過膜は、ろ過膜４２ａ、４２ｂ、４２ｃの３つであるが、数はこれに限られず、単数であっても複数であってもよい。以下、ろ過膜４２ａ、４２ｂ、４２ｃを区別しない場合は、ろ過膜４２と記載する。 FIG. 5: is a schematic diagram which shows one structural example of the membrane filtration part which concerns on 1st Embodiment. As shown in FIG. 5, the membrane filtration unit 4 includes a filtered water tank 40 and a plurality of filtration membranes 42a, 42b, 42c. In addition, in the present embodiment, the number of the filtration membranes is three, that is, the filtration membranes 42a, 42b, and 42c, but the number is not limited to this, and may be a single or a plurality. Hereinafter, when the filtration membranes 42a, 42b, 42c are not distinguished, they are referred to as the filtration membrane 42.

ろ過水槽４０は、内部にろ過膜４２を有する水槽である。ろ過水槽４０には、上述のろ過水管１４が接続されており、ろ過水管１４により、ろ過膜４２によってろ過されたろ過水Ｗ４を排出する。ろ過水槽４０からろ過水管１４を介して排出されたろ過水Ｗ４は、ろ過水槽４０の外部環境に排出される。 The filtered water tank 40 is a water tank having a filtration membrane 42 inside. The above-described filtered water pipe 14 is connected to the filtered water tank 40, and the filtered water W4 filtered by the filtering membrane 42 is discharged through the filtered water pipe 14. The filtered water W4 discharged from the filtered water tank 40 via the filtered water pipe 14 is discharged to the environment outside the filtered water tank 40.

ろ過膜４２は、第１の端部４４及び第２の端部４５が開口して、かつ内部が中空の円筒状の膜である。本実施形態におけるろ過膜４２は、ＭＦ（Micro Filtration）膜（精密ろ過膜）又はＵＦ（Ultra Filtration）膜（限外ろ過膜）である。ＭＦ膜は、例えば０．５μｍから０．１μｍの径の孔が多数形成された膜である。ＵＦ膜は、０．１μｍ以下の径の孔が多数形成された膜である。ただし、ろ過膜４２の形状は円筒に限られず、例えばシート状であってもよい。また、ろ過膜４２は、ろ材３５に付着していた微生物を捕集できる程度の孔径（微生物より小さい孔径）の膜であれば、ＭＦ膜又はＵＦ膜に限られない。 The filtration membrane 42 is a cylindrical membrane in which the first end 44 and the second end 45 are open and the inside is hollow. The filtration membrane 42 in the present embodiment is an MF (Micro Filtration) membrane (microfiltration membrane) or a UF (Ultra Filtration) membrane (ultrafiltration membrane). The MF film is a film in which a large number of holes each having a diameter of 0.5 μm to 0.1 μm are formed. The UF film is a film in which a large number of pores having a diameter of 0.1 μm or less are formed. However, the shape of the filtration membrane 42 is not limited to a cylinder, and may be, for example, a sheet shape. Further, the filtration membrane 42 is not limited to the MF membrane or the UF membrane as long as it is a membrane having a pore size (pore size smaller than that of microorganisms) capable of collecting the microorganisms attached to the filter medium 35.

ろ過膜４２は、第１の端部４４が処理水管１３に接続されており、第２の端部４５が膜濃縮水管１６に接続されている。図５の例では、処理水管１３が、処理水管１３ａ、１３ｂ、１３ｃに分岐しており、先端がろ過水槽４０の内部に挿入されている。処理水管１３ａは、ろ過膜４２ａの第１の端部４４に接続されており、処理水管１３ｂは、ろ過膜４２ｂの第１の端部４４に接続されており、処理水管１３ｃは、ろ過膜４２ｃの第１の端部４４に接続されている。図５の例では、膜濃縮水管１６が、膜濃縮水管１６ａ、１６ｂ、１６ｃに分岐しており、先端がろ過水槽４０の内部に挿入されている。膜濃縮水管１６ａは、ろ過膜４２ａの第２の端部４５に接続されており、膜濃縮水管１６ｂは、ろ過膜４２ｂの第２の端部４５に接続されており、膜濃縮水管１６ｃは、ろ過膜４２ｃの第２の端部４５に接続されている。 The first end 44 of the filtration membrane 42 is connected to the treated water pipe 13, and the second end 45 is connected to the membrane concentrated water pipe 16. In the example of FIG. 5, the treated water pipe 13 is branched into treated water pipes 13 a, 13 b, and 13 c, and the tip end is inserted into the filtered water tank 40. The treated water pipe 13a is connected to a first end 44 of the filtration membrane 42a, the treated water pipe 13b is connected to a first end 44 of the filtration membrane 42b, and the treated water pipe 13c is a filtration membrane 42c. Connected to the first end 44 of the. In the example of FIG. 5, the membrane-concentrated water pipe 16 is branched into the membrane-concentrated water pipes 16 a, 16 b, and 16 c, and the tip is inserted inside the filtered water tank 40. The membrane concentrated water pipe 16a is connected to the second end 45 of the filtration membrane 42a, the membrane concentrated water pipe 16b is connected to the second end 45 of the filtration membrane 42b, and the membrane concentrated water pipe 16c is It is connected to the second end 45 of the filtration membrane 42c.

次に、図５の矢印に示される処理水Ｗ３、ろ過水Ｗ４、及び膜濃縮水Ｗ５の流れを参照しつつ、膜ろ過部４によるろ過水Ｗ４と膜濃縮水Ｗ５とへの分離処理について説明する。 Next, with reference to the flows of the treated water W3, the filtered water W4, and the membrane concentrated water W5 shown by the arrows in FIG. 5, the separation treatment into the filtered water W4 and the membrane concentrated water W5 by the membrane filtration unit 4 will be described. To do.

散水ろ床部３から処理水管１３を介して流出した処理水Ｗ３は、処理水管１３ａ、１３ｂ、１３ｃに分岐して、ろ過膜４２ａ、４２ｂ、４２ｃの第１の端部４４からろ過膜４２ａ、４２ｂ、４２ｃ内に供給される。ろ過膜４２ａ、４２ｂ、４２ｃ（ろ過膜４２）内に供給された処理水Ｗ３は、第１の端部４４から第２の端部４５に向かって流れる。ろ過膜４２内の処理水Ｗ３の一部は、ろ過膜４２を透過して、ろ過水Ｗ４として、ろ過膜４２の外部、すなわちろ過水槽４０内に流出する。ろ過膜４２の孔よりも大きな固形物は、ろ過膜４２に捕集されて、ろ過膜４２を透過しない。ろ過水Ｗ４は、ろ過膜４２を透過した水であるため、ろ過膜４２の孔よりも大きな、ろ材３５表面から剥離した微生物などの固形物を含まない。ろ過膜４２内の処理水Ｗ３の他の一部は、ろ過膜４２に捕集された微生物等の固形物と共に、膜濃縮水Ｗ５として、膜濃縮水管１６ａ、１６ｂ、１６ｃから膜濃縮水管１６に排出される。このように、膜ろ過部４は、クロスフロー形式の膜ろ過装置である。なお、ろ過膜の外周側から中心部に向けて処理水Ｗ４を通水させる構成としてもよい。 The treated water W3 that has flowed out of the sprinkling filter section 3 through the treated water pipe 13 branches into the treated water pipes 13a, 13b, 13c, and from the first end 44 of the filtration membranes 42a, 42b, 42c to the filtration membrane 42a, It is supplied into 42b and 42c. The treated water W3 supplied into the filtration membranes 42a, 42b, 42c (filtration membrane 42) flows from the first end portion 44 toward the second end portion 45. A part of the treated water W3 in the filtration membrane 42 permeates the filtration membrane 42 and flows out as filtration water W4 outside the filtration membrane 42, that is, in the filtration water tank 40. Solid matter larger than the pores of the filtration membrane 42 is collected by the filtration membrane 42 and does not pass through the filtration membrane 42. Since the filtered water W4 is water that has permeated through the filtration membrane 42, it does not contain solid matter larger than the pores of the filtration membrane 42 and separated from the surface of the filter medium 35, such as microorganisms. The other part of the treated water W3 in the filtration membrane 42 is transferred to the membrane concentration water pipe 16 from the membrane concentration water pipes 16a, 16b, 16c as the membrane concentration water W5 together with solid matters such as microorganisms collected in the filtration membrane 42. Emitted. As described above, the membrane filtration unit 4 is a cross-flow type membrane filtration device. The treated water W4 may be passed from the outer peripheral side of the filtration membrane toward the center.

（膜濃縮水の返送について）
散水ろ床部３は、ろ材充填層３３ｂの空隙を処理用排水Ｗ２が通るため、ろ材３５の表面の微生物が、ろ材３５から剥がれ落ちる場合がある。ろ材３５から剥がれ落ちた微生物は、処理水Ｗ３に含まれて、散水ろ床部３の下流、すなわち膜ろ過部４に向けて排出される。ろ材３５の表面の微生物が剥がれ落ちた場合、ろ床本体３０内の微生物の数が減少して、散水ろ床部３の排水処理の性能が低下する。また、微生物を含んだ処理水がシステム系外に排出されてしまう問題もある。そこで、第１実施形態における排水処理システム１は、処理水Ｗ３をろ過膜４２で分離処理することにより、散水ろ床部３から排出された微生物をろ過膜４２で捕集する。そして、排水処理システム１は、捕集した微生物を、膜濃縮水Ｗ５として散水ろ床部３に返送する。これにより、剥がれ落ちた微生物をろ材充填層３３ｂに戻すことが可能となるため、ろ材３５表面の微生物の数の減少を抑制することができる。また、微生物のシステム系外への排出を防止することができる。 (About returning membrane concentrated water)
In the sprinkling filter part 3, the treatment wastewater W2 passes through the voids of the filter medium filling layer 33b, so that the microorganisms on the surface of the filter medium 35 may peel off from the filter medium 35. The microorganisms peeled off from the filter medium 35 are contained in the treated water W3 and discharged toward the downstream of the sprinkling filter section 3, that is, toward the membrane filtration section 4. When the microorganisms on the surface of the filter medium 35 are peeled off, the number of microorganisms in the filter bed body 30 is reduced, and the performance of the waste water treatment of the sprinkling filter section 3 is deteriorated. There is also a problem that treated water containing microorganisms is discharged outside the system. Therefore, the wastewater treatment system 1 in the first embodiment collects the microorganisms discharged from the sprinkling filter section 3 by the filtration membrane 42 by separating the treated water W3 by the filtration membrane 42. Then, the wastewater treatment system 1 returns the collected microorganisms to the sprinkling filter section 3 as the membrane concentrated water W5. As a result, the separated microorganisms can be returned to the filter medium filling layer 33b, so that the decrease in the number of microorganisms on the surface of the filter medium 35 can be suppressed. In addition, it is possible to prevent the discharge of microorganisms out of the system system.

本実施形態では、図１及び図３に示すように、剥がれ落ちた微生物を含む膜濃縮水Ｗ５は、膜濃縮水管１６及び散水ろ床接続管１７を介して、散水ろ床部３の回転式散水装置３１に返送される。膜濃縮水管１６は、膜ろ過部４におけるろ過膜４２の上流に接続されているため、ろ過膜４２を透過していない膜濃縮水Ｗ５を導通させている。また、散水ろ床接続管１７は、一方の端部が膜濃縮水管１６に接続され、他方の端部が回転式散水装置３１、すなわち、ろ床本体３０（ろ材充填層３３ｂ）の上流側に接続されている。従って、膜濃縮水Ｗ５は、膜濃縮水管１６及び散水ろ床接続管１７を通って、ろ材充填層３３ｂに供給される。ろ材充填層３３ｂ内に供給された膜濃縮水Ｗ５に含まれた微生物は、ろ材３５表面に付着する。 In the present embodiment, as shown in FIGS. 1 and 3, the membrane concentrated water W5 containing the separated microorganisms is a rotary type of the water sprinkling filter section 3 via a membrane concentrated water pipe 16 and a sprinkling filter connecting pipe 17. It is returned to the sprinkler 31. Since the membrane concentrated water pipe 16 is connected to the upstream side of the filtration membrane 42 in the membrane filtration unit 4, it conducts the membrane concentrated water W5 that has not permeated the filtration membrane 42. In addition, one end of the sprinkling filter bed connection pipe 17 is connected to the membrane concentrated water pipe 16, and the other end of the sprinkling filter connection pipe 17 is on the upstream side of the rotary sprinkler 31, that is, the filter bed main body 30 (filter medium packed layer 33b). It is connected. Therefore, the membrane concentrated water W5 is supplied to the filter medium packed layer 33b through the membrane concentrated water pipe 16 and the sprinkling filter connection pipe 17. The microorganisms contained in the membrane concentrated water W5 supplied into the filter medium filling layer 33b adhere to the surface of the filter medium 35.

また、図１及び図２に示すように、膜濃縮水Ｗ５は、膜濃縮水管１６及び固液分離接続管１８を介して、固液分離部２の分配槽２０に返送される。固液分離接続管１８は、一方の端部が、散水ろ床接続管１７と並列に膜濃縮水管１６に接続されている。固液分離接続管１８は、他方の端部が、分配槽２０、すなわち固液分離部２の上流側に開口している。従って、膜濃縮水Ｗ５は、膜濃縮水管１６及び固液分離接続管１８を通って、分配槽２０内に供給される。膜濃縮水Ｗ５は、散水ろ床部３を経由した水であるため、溶存酸素量が比較的大きくなる。溶存酸素量が大きい膜濃縮水Ｗ５が固液分離部２に供給されることで、この酸素を用いた生物処理を、固液分離部２内でも適切に行うことができる。この固液分離部２における生物処理は、膜濃縮水Ｗ５に含まれる微生物以外の、排水Ｗ１に含まれた他の微生物による処理であるが、膜濃縮水Ｗ５に含まれる微生物による処理であってもよい。 Further, as shown in FIGS. 1 and 2, the membrane concentrated water W5 is returned to the distribution tank 20 of the solid-liquid separation section 2 via the membrane concentrated water pipe 16 and the solid-liquid separation connecting pipe 18. One end of the solid-liquid separation connecting pipe 18 is connected to the membrane concentrated water pipe 16 in parallel with the sprinkling filter connecting pipe 17. The other end of the solid-liquid separation connecting pipe 18 is open to the distribution tank 20, that is, the upstream side of the solid-liquid separation unit 2. Therefore, the membrane concentrated water W5 is supplied into the distribution tank 20 through the membrane concentrated water pipe 16 and the solid-liquid separation connecting pipe 18. Since the membrane concentrated water W5 is the water that has passed through the sprinkling filter part 3, the dissolved oxygen amount becomes relatively large. By supplying the membrane concentrated water W5 having a large dissolved oxygen amount to the solid-liquid separation unit 2, it is possible to appropriately perform biological treatment using this oxygen even in the solid-liquid separation unit 2. The biological treatment in the solid-liquid separation unit 2 is a treatment by other microorganisms contained in the wastewater W1 other than the microorganisms contained in the membrane concentrated water W5, but is a treatment by the microorganisms contained in the membrane concentrated water W5. Good.

このように、膜濃縮水Ｗ５は、一部が散水ろ床部３に返送され、他の一部が固液分離部２に返送される。この膜濃縮水Ｗ５の返送量は、制御部６による膜濃縮水供給弁１７ａ、及び膜濃縮水供給弁１８ａの開閉操作によって、制御される。制御部６は、水質測定部５による処理水Ｗ３の水質の計測結果に基づき、固液分離部２及び散水ろ床部３への膜濃縮水Ｗ５の返送量を決定する。 Thus, a part of the membrane concentrated water W5 is returned to the sprinkling filter part 3 and another part is returned to the solid-liquid separation part 2. The return amount of the membrane concentrated water W5 is controlled by the opening/closing operation of the membrane concentrated water supply valve 17a and the membrane concentrated water supply valve 18a by the control unit 6. The control unit 6 determines the return amount of the membrane concentrated water W5 to the solid-liquid separation unit 2 and the sprinkling filter unit 3 based on the measurement result of the water quality of the treated water W3 by the water quality measurement unit 5.

以下、膜濃縮水の返送量の決定方法について詳細に説明する。水質測定部５は、散水ろ床部３の下流（散水ろ床部３と膜ろ過部４との間）の処理水管１３を流れる処理水Ｗ３の水質を計測する。具体的には、水質測定部５は、処理水Ｗ３内に含まれるアンモニア性窒素濃度、又は溶存酸素量を検出する。水質測定部５は、例えば、イオン選択電極式のアンモニア性窒素濃度計、隔膜電極式の溶存酸素濃度計である。アンモニア性窒素とは、アンモニウムイオンをその窒素量で表したものである。処理水Ｗ３のアンモニア性窒素濃度は、処理水Ｗ３内に含まれるアンモニア性窒素の濃度のことをいう。水質測定部５は、アンモニア性窒素濃度を直接検出してもよいし、処理水Ｗ３中の全窒素量ならびに酸化態窒素濃度を検出し、そこからアンモニア性窒素濃度を算出してもよい。処理水Ｗ３の溶存酸素量とは、処理水Ｗ３内に溶存している酸素の量である。水質測定部５は、アンモニア性窒素濃度、又は溶存酸素量のいずれか一方を検出してもよいし、両方を検出してもよい。 Hereinafter, the method for determining the return amount of the membrane concentrated water will be described in detail. The water quality measurement unit 5 measures the water quality of the treated water W3 flowing through the treated water pipe 13 downstream of the sprinkling filter unit 3 (between the sprinkling filter unit 3 and the membrane filtration unit 4). Specifically, the water quality measuring unit 5 detects the concentration of ammonia nitrogen contained in the treated water W3 or the amount of dissolved oxygen. The water quality measuring unit 5 is, for example, an ion selective electrode type ammonia nitrogen concentration meter or a diaphragm electrode type dissolved oxygen concentration meter. Ammoniacal nitrogen is an ammonium ion represented by its nitrogen content. The ammonia nitrogen concentration of the treated water W3 refers to the concentration of ammonia nitrogen contained in the treated water W3. The water quality measuring unit 5 may directly detect the ammonia nitrogen concentration, or may detect the total nitrogen amount and oxidized nitrogen concentration in the treated water W3 and calculate the ammonia nitrogen concentration therefrom. The dissolved oxygen amount of the treated water W3 is the amount of oxygen dissolved in the treated water W3. The water quality measuring unit 5 may detect either the ammonia nitrogen concentration or the dissolved oxygen amount, or may detect both.

制御部６は、水質測定部５が計測した処理水Ｗ３中のアンモニア性窒素濃度、又は溶存酸素量に基づき、膜濃縮水供給弁１７ａの開閉量を制御し、散水ろ床部３（ろ材充填層３３ｂ）に返送する膜濃縮水Ｗ５の量を制御する。制御部６は、処理水Ｗ３中のアンモニア性窒素濃度が所定濃度より大きくなった場合に、散水ろ床部３（ろ材充填層３３ｂ）に返送する膜濃縮水Ｗ５の量を増加させる。また、制御部６は、処理水Ｗ３中の溶存酸素量が所定量より小さくなった場合に、散水ろ床部３（ろ材充填層３３ｂ）に返送する膜濃縮水Ｗ５の量を増加させる。制御部６は、アンモニア性窒素濃度が所定濃度より大きくなった場合、微生物による生物処理が十分でないと判断して、散水ろ床部３に返送する膜濃縮水Ｗ５の量を増加させる。同様に、制御部６は、溶存酸素量が所定量より小さくなった場合、ろ材充填層３３ｂにおける酸素量が減って、微生物が十分に生物処理を行うことができなくなっていると判断して、散水ろ床部３に返送する膜濃縮水Ｗ５の量を増加させる。制御部６は、アンモニア性窒素濃度、又は溶存酸素量のいずれかに基づき散水ろ床部３に返送する膜濃縮水Ｗ５の量を制御してもよいし、アンモニア性窒素濃度及び溶存酸素量の両方に基づき散水ろ床部３に返送する膜濃縮水Ｗ５の量を制御してもよい。 The control unit 6 controls the opening/closing amount of the membrane concentrated water supply valve 17a based on the concentration of ammonia nitrogen in the treated water W3 measured by the water quality measuring unit 5 or the amount of dissolved oxygen, and controls the sprinkling filter unit 3 (filter medium filling). The amount of the membrane concentrated water W5 returned to the layer 33b) is controlled. The control unit 6 increases the amount of the membrane concentrated water W5 returned to the sprinkling filter unit 3 (filter medium packed layer 33b) when the concentration of ammonia nitrogen in the treated water W3 becomes higher than a predetermined concentration. Further, when the amount of dissolved oxygen in the treated water W3 becomes smaller than a predetermined amount, the control unit 6 increases the amount of the membrane concentrated water W5 returned to the sprinkling filter unit 3 (filter medium packed layer 33b). When the ammonia nitrogen concentration becomes higher than the predetermined concentration, the control unit 6 determines that the biological treatment by the microorganism is not sufficient, and increases the amount of the membrane concentrated water W5 returned to the sprinkling filter unit 3. Similarly, when the dissolved oxygen amount becomes smaller than a predetermined amount, the control unit 6 determines that the oxygen amount in the filter medium packed layer 33b is reduced and the microorganisms cannot perform biological treatment sufficiently, The amount of the membrane concentrated water W5 returned to the sprinkling filter section 3 is increased. The control unit 6 may control the amount of the membrane concentrated water W5 returned to the sprinkling filter unit 3 based on either the ammonia nitrogen concentration or the dissolved oxygen amount, or the ammonia nitrogen concentration and the dissolved oxygen amount may be controlled. The amount of the membrane concentrated water W5 returned to the sprinkling filter section 3 may be controlled based on both.

水質測定部５は、処理水Ｗ３の代わりに、散水ろ床部３の下流であって、膜ろ過部４（ろ過膜４２）の下流のろ過水管１４を流れるろ過水Ｗ４の水質を計測してもよい。この場合、制御部６は、ろ過水Ｗ４の水質測定結果に基づき、散水ろ床部３に返送する膜濃縮水Ｗ５の量を制御する。すなわち、水質測定部５は、散水ろ床部３の下流側の生物処理後の水質を計測すればよく、制御部６は、散水ろ床部３の下流側の生物処理後の水質に基づき散水ろ床部３に返送する膜濃縮水Ｗ５の量を制御すればよい。以上をまとめると、水質測定部５は、処理水Ｗ３のアンモニア性窒素濃度、処理水Ｗ３の溶存酸素量、ろ過水Ｗ４のアンモニア性窒素濃度、及びろ過水Ｗ４の溶存酸素量のうち、少なくともいずれか１つを測定する。制御部６は、処理水Ｗ３のアンモニア性窒素濃度、処理水Ｗ３の溶存酸素量、ろ過水Ｗ４のアンモニア性窒素濃度、及びろ過水Ｗ４の溶存酸素量の測定結果のうち、少なくともいずれか１つに基づき、散水ろ床部３に返送する膜濃縮水Ｗ５の量を制御する。 Instead of the treated water W3, the water quality measurement unit 5 measures the water quality of the filtered water W4 that is downstream of the sprinkling filter unit 3 and that flows through the filtered water pipe 14 downstream of the membrane filtration unit 4 (filtration membrane 42). Good. In this case, the control unit 6 controls the amount of the membrane concentrated water W5 returned to the sprinkling filter unit 3 based on the water quality measurement result of the filtered water W4. That is, the water quality measuring unit 5 may measure the water quality after biological treatment on the downstream side of the sprinkling filter unit 3, and the control unit 6 sprinkles water based on the water quality after biological treatment on the downstream side of the sprinkling filter unit 3. The amount of the membrane concentrated water W5 returned to the filter bed part 3 may be controlled. To summarize the above, the water quality measurement unit 5 uses at least one of the ammonia nitrogen concentration of the treated water W3, the dissolved oxygen amount of the treated water W3, the ammonia nitrogen concentration of the filtered water W4, and the dissolved oxygen amount of the filtered water W4. Measure one or the other. The control unit 6 includes at least one of the ammonia nitrogen concentration of the treated water W3, the dissolved oxygen amount of the treated water W3, the ammonia nitrogen concentration of the filtered water W4, and the dissolved oxygen amount of the filtered water W4. Based on the above, the amount of the membrane concentrated water W5 returned to the sprinkling filter section 3 is controlled.

また、水質測定部５は、散水ろ床部３の上流（固液分離部２と散水ろ床部３との間）の処理用排水管１２を流れる処理用排水Ｗ２の水質も計測してよい。この場合、制御部６は、処理用排水Ｗ２と、処理水Ｗ３（又はろ過水Ｗ４）との水質の比較結果に基づき、散水ろ床部３に返送する膜濃縮水Ｗ５の量を制御する。例えば、制御部６は、処理用排水Ｗ２のアンモニア性窒素濃度と処理水Ｗ３のアンモニア性窒素濃度との差（処理用排水Ｗ２のアンモニア性窒素濃度から処理水Ｗ３のアンモニア性窒素濃度を引いた値）が、所定の値よりも小さくなった場合、微生物による生物処理が十分でないと判断して、散水ろ床部３に返送する膜濃縮水Ｗ５の量を増加させる。この場合、制御部６は、処理用排水Ｗ２のアンモニア性窒素濃度と処理水Ｗ３のアンモニア性窒素濃度との差が、所定の値よりも小さくなり、かつ、処理水Ｗ３のアンモニア性窒素濃度の値が所定濃度より大きくなった場合に、散水ろ床部３に返送する膜濃縮水Ｗ５の量を増加させてもよい。 The water quality measuring unit 5 may also measure the water quality of the treatment wastewater W2 flowing through the treatment drain pipe 12 upstream of the sprinkling filter unit 3 (between the solid-liquid separating unit 2 and the sprinkling filter unit 3). .. In this case, the control unit 6 controls the amount of the membrane concentrated water W5 returned to the sprinkling filter unit 3 based on the comparison result of the water qualities of the treatment wastewater W2 and the treated water W3 (or the filtered water W4). For example, the control unit 6 subtracts the ammonia nitrogen concentration of the treated water W3 from the ammonia nitrogen concentration of the treated water W2 and the ammonia nitrogen concentration of the treated water W3 (the ammonia nitrogen concentration of the treated water W3 is subtracted from the ammonia nitrogen concentration of the treatment drain W2). When the value) becomes smaller than a predetermined value, it is determined that the biological treatment by the microorganism is not sufficient, and the amount of the membrane concentrated water W5 returned to the sprinkling filter part 3 is increased. In this case, the control unit 6 determines that the difference between the ammonia nitrogen concentration of the treated waste water W2 and the ammonia nitrogen concentration of the treated water W3 becomes smaller than a predetermined value, and the ammonia nitrogen concentration of the treated water W3 is reduced. When the value becomes larger than the predetermined concentration, the amount of the membrane concentrated water W5 returned to the sprinkling filter section 3 may be increased.

また、制御部６は、処理用排水Ｗ２の溶存酸素量と処理水Ｗ３の溶存酸素量との差（処理用排水Ｗ２の溶存酸素量から処理水Ｗ３の溶存酸素量を引いた値）が、所定の値よりも大きくなった場合、ろ材充填層３３ｂにおける酸素量が減って、微生物が十分に生物処理を行うことができなくなっていると判断して、散水ろ床部３に返送する膜濃縮水Ｗ５の量を増加させてもよい。この場合、制御部６は、処理用排水Ｗ２の溶存酸素量と処理水Ｗ３の溶存酸素量との差が所定の値よりも大きくなり、かつ、処理水Ｗ３中の溶存酸素量が所定量より小さくなった場合に、散水ろ床部３に返送する膜濃縮水Ｗ５の量を増加させてもよい。 Further, the control unit 6 determines that the difference between the amount of dissolved oxygen in the treatment wastewater W2 and the amount of dissolved oxygen in the treated water W3 (a value obtained by subtracting the amount of dissolved oxygen in the treated water W3 from the amount of dissolved oxygen in the treated wastewater W2). When it becomes larger than a predetermined value, the amount of oxygen in the filter medium packed layer 33b is reduced and it is judged that the microorganisms cannot sufficiently perform biological treatment, and the membrane concentration is returned to the sprinkling filter bed section 3. The amount of water W5 may be increased. In this case, the control unit 6 determines that the difference between the amount of dissolved oxygen in the treatment wastewater W2 and the amount of dissolved oxygen in the treated water W3 is larger than a predetermined value, and the amount of dissolved oxygen in the treated water W3 is smaller than the predetermined amount. When it becomes small, the amount of the membrane concentrated water W5 returned to the sprinkling filter part 3 may be increased.

次に、膜濃縮水Ｗ５の返送量を変更する方法について説明する。制御部６は、通常時制御Ａにおいて、膜濃縮水供給弁１７ａ及び膜濃縮水供給弁１８ａを所定の開度に保つことで、散水ろ床部３に返送する膜濃縮水Ｗ５の量、及び固液分離部２に返送する膜濃縮水Ｗ５の量を、通常時制御Ａにおいて定めた量である通常量に保っている。通常時制御Ａとは、制御部６が、散水ろ床部３に返送する膜濃縮水Ｗ５の量を増加させなくてもよいと判断した通常時における流量制御を意味する。以下、散水ろ床部３に返送する膜濃縮水Ｗ５の量を、ろ床返送量Ｑ１とし、固液分離部２に返送する膜濃縮水Ｗ５の量を、固液分離返送量Ｑ２と記載する。 Next, a method of changing the return amount of the membrane concentrated water W5 will be described. In the normal time control A, the control unit 6 maintains the membrane concentrated water supply valve 17a and the membrane concentrated water supply valve 18a at a predetermined opening degree, so that the amount of the membrane concentrated water W5 returned to the sprinkling filter unit 3, and The amount of the membrane concentrated water W5 returned to the solid-liquid separation unit 2 is maintained at the normal amount that is the amount determined in the normal time control A. The normal time control A means the flow rate control in the normal time when the control unit 6 determines that the amount of the membrane concentrated water W5 returned to the sprinkling filter unit 3 does not have to be increased. Hereinafter, the amount of the membrane concentrated water W5 returned to the sprinkling filter part 3 will be referred to as a filter bed returned amount Q1, and the amount of the membrane concentrated water W5 returned to the solid-liquid separation part 2 will be referred to as a solid-liquid separation returned amount Q2. ..

制御部６は、ろ床返送量増加制御Ｂにおいて、ろ床返送量Ｑ１を、通常量よりも増加させる。ろ床返送量増加制御Ｂとは、制御部６が、散水ろ床部３に返送する膜濃縮水Ｗ５の量を増加させると判断した場合における制御のことを指す。具体的には、制御部６は、ろ床返送量増加制御Ｂにおいて、固液分離返送量Ｑ２を通常量に維持としつつ、ろ床返送量Ｑ１を、通常量よりも増加させる。また、制御部６は、ろ床返送量増加制御Ｂにおいて、ろ床返送量Ｑ１と固液分離返送量Ｑ２との割合を変更して、ろ床返送量Ｑ１を増加させ固液分離返送量Ｑ２を減少させることにより、ろ床返送量Ｑ１を、通常量よりも増加させてもよい。この場合、ろ床返送量Ｑ１と固液分離返送量Ｑ２との総量は、通常時と同量としてもよいし、ろ床返送量Ｑ１と固液分離返送量Ｑ２との総量を通常時から増加させてもよい。以下、この膜濃縮水の返送量の変更例について説明する。 In the filter bed return amount increase control B, the control unit 6 increases the filter bed return amount Q1 above the normal amount. The filter bed return amount increase control B refers to control in the case where the control unit 6 determines to increase the amount of the membrane concentrated water W5 returned to the sprinkling filter unit 3. Specifically, in the filter bed return amount increase control B, the control unit 6 increases the filter bed return amount Q1 above the normal amount while maintaining the solid-liquid separation return amount Q2 at the normal amount. Further, in the filter bed return amount increase control B, the control unit 6 changes the ratio of the filter bed return amount Q1 and the solid-liquid separation return amount Q2 to increase the filter bed return amount Q1 and increase the solid-liquid separation return amount Q2. The filter bed return amount Q1 may be increased more than the normal amount by decreasing. In this case, the total amount of the filter bed return amount Q1 and the solid-liquid separation return amount Q2 may be the same amount as the normal time, or the total amount of the filter bed return amount Q1 and the solid-liquid separation return amount Q2 is increased from the normal time. You may let me. Hereinafter, an example of changing the return amount of the membrane concentrated water will be described.

図６は、膜濃縮水の返送量の変更例を説明する表である。図１に示すように、排水管１１内であって、固液分離接続管１８との合流部よりも上流側で排水Ｗ１が流れるポイントを、ポイントＰ１とする。処理用排水管１２内であって、散水ろ床接続管１７との合流部よりも上流側で処理用排水Ｗ２が流れるポイントを、ポイントＰ２とする。処理水管１３内であって、処理水Ｗ３が流れるポイントを、ポイントＰ３とする。ろ過水管１４内であって、ろ過水Ｗ４が流れるポイントを、ポイントＰ４とする。散水ろ床接続管１７内であって、処理用排水管１２との合流部よりも上流側で膜濃縮水Ｗ５が流れるポイントを、ポイントＰ５とする。固液分離接続管１８内であって、排水管１１との合流部よりも上流側で膜濃縮水Ｗ５が流れるポイントを、ポイントＰ６とする。 FIG. 6 is a table illustrating an example of changing the return amount of the membrane concentrated water. As shown in FIG. 1, the point in the drainage pipe 11 where the drainage W1 flows on the upstream side of the confluence with the solid-liquid separation connecting pipe 18 is referred to as a point P1. A point in the treatment drainage pipe 12 where the treatment wastewater W2 flows on the upstream side of the confluence with the sprinkling filter connection pipe 17 is referred to as a point P2. A point in the treated water pipe 13 where the treated water W3 flows is referred to as a point P3. The point in the filtered water pipe 14 where the filtered water W4 flows is designated as point P4. The point in the sprinkling filter connection pipe 17 where the membrane concentrated water W5 flows on the upstream side of the confluence with the treatment drain pipe 12 is designated as point P5. The point in the solid-liquid separation connecting pipe 18 where the membrane concentrated water W5 flows on the upstream side of the confluence portion with the drain pipe 11 is designated as point P6.

ポイントＰ１での流量は、排水処理システム１に供給される排水Ｗ１の総量となる。ポイントＰ５での流量は、ろ床返送量Ｑ１となり、ポイントＰ６での流量は、固液分離返送量Ｑ２となる。ポイントＰ２での流量は、処理用排水Ｗ２の流量、すなわち、ポイントＰ１での流量（排水Ｗ１）とポイントＰ６での流量（固液分離返送量Ｑ２）とを合算した流量となる。ポイントＰ３での流量は、処理水Ｗ３の流量、すなわち、ポイントＰ２での流量（処理用排水Ｗ２）とポイントＰ５での流量（ろ床返送量Ｑ１）とを合算した流量となる。ポイントＰ４での流量は、ろ過水Ｗ４の流量、すなわち、ポイントＰ３での流量（処理水Ｗ３）から、ポイントＰ５、Ｐ６での流量（ろ床返送量Ｑ１と固液分離返送量Ｑ２との総量）を差し引いた量となる。 The flow rate at the point P1 is the total amount of the wastewater W1 supplied to the wastewater treatment system 1. The flow rate at point P5 is the filter bed return quantity Q1, and the flow rate at point P6 is the solid-liquid separation return quantity Q2. The flow rate at the point P2 is the flow rate of the treatment wastewater W2, that is, the sum of the flow rate at the point P1 (wastewater W1) and the flow rate at the point P6 (solid-liquid separation return quantity Q2). The flow rate at the point P3 is the flow rate of the treated water W3, that is, the sum of the flow rate at the point P2 (treatment wastewater W2) and the flow rate at the point P5 (filter bed return amount Q1). The flow rate at point P4 is the flow rate of filtered water W4, that is, the flow rate at point P3 (treated water W3), and the flow rate at points P5 and P6 (total amount of filter bed return amount Q1 and solid-liquid separation return amount Q2). ) Is subtracted.

図６の例では、ポイントＰ１での流量、すなわち流入してくる排水Ｗ１の量を１．０とし、ポイントＰ４での流量、すなわち排水処理後に外部に戻すろ過水Ｗ４の量を１．０としている。図６の例では、通常時制御Ａにおいて、ポイントＰ５での流量と、ポイントＰ６での流量とを、０．５としている。すなわち、ろ床返送量Ｑ１の通常量は、固液分離返送量Ｑ２の通常量と同じになっている。通常時制御ＡにおけるポイントＰ２の流量（処理用排水Ｗ２の流量）は、１．５であり、ポイントＰ３の流量（処理水Ｗ３の流量）は、２．０である。 In the example of FIG. 6, the flow rate at the point P1, that is, the amount of the inflowing wastewater W1 is set to 1.0, and the flow rate at the point P4, that is, the amount of the filtered water W4 returned to the outside after the wastewater treatment is set to 1.0. There is. In the example of FIG. 6, in the normal control A, the flow rate at the point P5 and the flow rate at the point P6 are set to 0.5. That is, the normal amount of the filter bed return amount Q1 is the same as the normal amount of the solid-liquid separation return amount Q2. The flow rate at point P2 (flow rate of treatment wastewater W2) in normal-time control A is 1.5, and the flow rate at point P3 (flow rate of treated water W3) is 2.0.

図６の例では、制御部６は、ろ床返送量増加制御Ｂ１において、ポイントＰ５での流量（ろ床返送量Ｑ１）を、０．８に増加させる一方、ポイントＰ６での流量（固液分離返送量Ｑ２）を変化させず０．５のままとしている。この場合、ポイントＰ２の流量（処理用排水Ｗ２の流量）は、１．５であり、ポイントＰ３の流量（処理水Ｗ３の流量）は、２．３である。すなわち、ろ床返送量増加制御Ｂ１は、固液分離返送量Ｑ２を通常量のままとしつつ、ろ床返送量Ｑ１を、通常量よりも増加させた場合の例を説明している。この場合、膜濃縮水Ｗ５の総量（ろ床返送量Ｑ１と固液分離返送量Ｑ２との合計）が通常時制御Ａより増加しているが、膜濃縮水Ｗ５の増加分は、ポイントＰ３の流量（処理水Ｗ３の流量）、すなわち散水ろ床部３からの排水量を強制的に増加させることにより補填する。 In the example of FIG. 6, the control unit 6 increases the flow rate at the point P5 (filter bed return amount Q1) to 0.8 in the filter bed return amount increase control B1, while the flow rate at the point P6 (solid-liquid amount). The separation/return amount Q2) is not changed and remains 0.5. In this case, the flow rate at point P2 (flow rate of treatment wastewater W2) is 1.5, and the flow rate at point P3 (flow rate of treated water W3) is 2.3. That is, the filter bed return amount increase control B1 describes an example in which the filter bed return amount Q1 is increased from the normal amount while keeping the solid-liquid separation return amount Q2 at the normal amount. In this case, the total amount of the membrane concentrated water W5 (the total amount of the filter bed return amount Q1 and the solid-liquid separation return amount Q2) is higher than that in the normal control A, but the increase amount of the membrane concentrated water W5 is equal to the point P3. The flow rate (flow rate of the treated water W3), that is, the amount of drainage from the sprinkling filter section 3 is forcibly increased to compensate.

図６の例では、制御部６は、ろ床返送量増加制御Ｂ２において、ポイントＰ５での流量（ろ床返送量Ｑ１）を、０．８に増加させる一方、ポイントＰ６での流量（固液分離返送量Ｑ２）を、０．２に減少させている。この場合、ポイントＰ２の流量（処理用排水Ｗ２の流量）は、１．２であり、ポイントＰ３の流量（処理水Ｗ３の流量）は、２．０である。すなわち、ろ床返送量増加制御Ｂ２は、膜濃縮水Ｗ５の総量（ろ床返送量Ｑ１と固液分離返送量Ｑ２との合計）を通常時と同じに保ちつつ、ろ床返送量Ｑ１と固液分離返送量Ｑ２との割合を変更して、ろ床返送量Ｑ１を増加させ固液分離返送量Ｑ２を減少させることにより、ろ床返送量Ｑ１を、通常量よりも増加させた例である。ろ床返送量増加制御Ｂ２のような制御とした場合、膜濃縮水Ｗ５の総量を通常時制御Ａと同じにすることができるため、散水ろ床部３からの排水量を変更する必要がない。 In the example of FIG. 6, the control unit 6 increases the flow rate at the point P5 (filter bed return amount Q1) to 0.8 in the filter bed return amount increase control B2, while increasing the flow rate at the point P6 (solid-liquid flow rate). The separated return amount Q2) is reduced to 0.2. In this case, the flow rate at the point P2 (flow rate of the treatment wastewater W2) is 1.2, and the flow rate at the point P3 (flow rate of the treated water W3) is 2.0. That is, the filter bed return amount increase control B2 keeps the total amount of the membrane concentrated water W5 (the sum of the filter bed return amount Q1 and the solid-liquid separation return amount Q2) at the same level as in the normal state, while maintaining the filter bed return amount Q1 and the solid state. This is an example of increasing the filter bed return amount Q1 from the normal amount by changing the ratio with the liquid separation return amount Q2 and increasing the filter bed return amount Q1 and decreasing the solid-liquid separation return amount Q2. .. When the control such as the filter bed return amount increase control B2 is performed, the total amount of the membrane concentrated water W5 can be the same as that in the normal time control A, so that it is not necessary to change the discharge amount from the sprinkling filter section 3.

制御部６は、ろ床返送量Ｑ１を増加させると判断した場合、ろ床返送量増加制御Ｂ１のように、膜濃縮水Ｗ５の総量を増加させつつ、ろ床返送量Ｑ１のみを増加させてもよい。また、制御部６は、ろ床返送量Ｑ１を増加させると判断した場合、ろ床返送量増加制御Ｂ２のように、膜濃縮水Ｗ５の総量をそのままに保ちつつ、ろ床返送量Ｑ１と固液分離返送量Ｑ２との割合を変更させてもよい。制御部６は、ろ床返送量増加制御Ｂ１、Ｂ２のいずれの制御とするかを、適宜判断してもよいし、予め定めたいずれかの制御のみを適用してもよい。 When it is determined that the filter bed return amount Q1 is increased, the control unit 6 increases only the filter bed return amount Q1 while increasing the total amount of the membrane concentrated water W5 as in the filter bed return amount increase control B1. Good. Further, when it is determined that the filter bed return amount Q1 is increased, the control unit 6 keeps the total amount of the membrane concentrated water W5 as it is, as in the filter bed return amount increase control B2, and fixes the filter bed return amount Q1. The ratio with the liquid separation and return amount Q2 may be changed. The control unit 6 may appropriately determine which control of the filter bed return amount increase control B1 and B2, or may apply only one of the predetermined controls.

次に、以上説明した膜濃縮水Ｗ５の返送量の制御について、フローチャートに基づき説明する。図７は、第１実施形態に係る膜濃縮水の返送量の制御を説明するフローチャートである。図７に示すように、制御部６は、水質測定部５から、処理水Ｗ３の水質測定の計測データを取得し（ステップＳ１０）、処理水Ｗ３のアンモニア性窒素濃度、又は溶存酸素量が、閾値の範囲外であるかを判断する（ステップＳ１２）。例えば、制御部６は、処理水Ｗ３のアンモニア窒素濃度が、所定濃度より大きいか、又は処理水Ｗ３の溶存酸素量が、所定量より小さいかを判断する。処理水Ｗ３のアンモニア性窒素濃度、又は溶存酸素量が、閾値の範囲外でない場合（ステップＳ１２：Ｎｏ）、制御部６は、ろ床返送量Ｑ１を、通常量（通常量のまま）とする（ステップＳ１４）。また、処理水Ｗ３のアンモニア性窒素濃度、又は溶存酸素量が、閾値の範囲外である場合（ステップＳ１２：Ｙｅｓ）、制御部６は、ろ床返送量Ｑ１を、通常量から増加させる（ステップＳ１６）。ろ床返送量Ｑ１を増加させた後は、ステップＳ１０に戻り、ろ床返送量Ｑ１増加後から所定時間経過後の処理水Ｗ３の水質測定データを取得し、同様の処理を繰り返す。例えば、この処理水Ｗ３のアンモニア性窒素濃度、又は溶存酸素量が、閾値内になった場合は、ステップＳ１４において、ろ床返送量Ｑ１を通常量に戻す。 Next, control of the return amount of the membrane concentrated water W5 described above will be described based on a flowchart. FIG. 7 is a flowchart illustrating control of the return amount of the membrane concentrated water according to the first embodiment. As shown in FIG. 7, the control unit 6 acquires the measurement data of the water quality measurement of the treated water W3 from the water quality measuring unit 5 (step S10), and the ammonia nitrogen concentration of the treated water W3 or the dissolved oxygen amount is It is determined whether it is outside the threshold range (step S12). For example, the control unit 6 determines whether the ammonia nitrogen concentration of the treated water W3 is higher than a predetermined concentration or the dissolved oxygen amount of the treated water W3 is smaller than a predetermined amount. When the ammonia nitrogen concentration or the dissolved oxygen amount of the treated water W3 is not outside the threshold range (step S12: No), the control unit 6 sets the filter bed return amount Q1 to the normal amount (the normal amount remains). (Step S14). Further, when the ammonia nitrogen concentration or the dissolved oxygen amount of the treated water W3 is out of the threshold range (step S12: Yes), the control unit 6 increases the filter bed return amount Q1 from the normal amount (step S12). S16). After increasing the filter bed return amount Q1, the process returns to step S10 to acquire the water quality measurement data of the treated water W3 after a predetermined time has elapsed after the filter bed return amount Q1 was increased, and the same process is repeated. For example, when the ammonia nitrogen concentration or the dissolved oxygen amount of the treated water W3 is within the threshold value, the filter bed return amount Q1 is returned to the normal amount in step S14.

ステップＳ１４の後、制御部６は、この処理を終了するか判断し（ステップＳ１８）、終了しない場合（ステップＳ１８：Ｎｏ）は、ステップＳ１０に戻り同様の処理を繰り返し、終了する場合（ステップＳ１８：Ｙｅｓ）は、この処理を終了する。 After step S14, the control unit 6 determines whether or not to end this processing (step S18), and when not ending (step S18: No), returns to step S10 and repeats similar processing, and ends (step S18). : Yes) ends this process.

以上説明したように、制御部６は、水質測定部５の水質測定結果に基づき、ろ床返送量Ｑ１を制御するが、それに加え、他の条件によってもろ床返送量Ｑ１を制御してもよい。図８は、ろ床返送量の制御の一例を説明するグラフである。図８の横軸は、１日における時刻を表しており、縦軸は、ろ床返送量Ｑ１を表している。図８に示すように、制御部６は、昼の時間帯におけるろ床返送量Ｑ１を夜の時間帯よりも大きくし、夜の時間帯におけるろ床返送量Ｑ１を昼の時間帯よりも小さくしてもよい。図８で提示した例では、昼の時間帯には排水Ｗ１の総量が大きくなり、夜の時間帯には排水Ｗ１の総量が小さいことから、制御部６は、昼の時間帯におけるろ床返送量Ｑ１を大きくして、処理能力を向上させている。言い換えれば、制御部６は、排水Ｗ１の総量が大きくなる時間帯ほどろ床返送量Ｑ１を大きくし、排水Ｗ１の総量が小さくなる時間帯ほどろ床返送量Ｑ１が小さくなるように、時間毎にろ床返送量Ｑ１を決定する。制御部６は、１日における排水Ｗ１の総量変化の情報に基づき、予め定められた比率で、１日における時間毎のろ床返送量Ｑ１を変化させるものであれば、その比率は、図８に示したもの（昼１２時のろ床返送量Ｑ１が最も高い）に限られない。また、制御部６は、予め比率を定めることに限られず、排水Ｗ１の流量を逐次測定し、その測定結果に基づき、ろ床返送量Ｑ１を逐次変化させてもよい。 As described above, the control unit 6 controls the filter bed return amount Q1 based on the water quality measurement result of the water quality measuring unit 5, but in addition to this, the filter bed return amount Q1 may be controlled by other conditions. .. FIG. 8 is a graph illustrating an example of control of the filter bed return amount. The horizontal axis of FIG. 8 represents the time of day, and the vertical axis represents the filter bed return amount Q1. As shown in FIG. 8, the control unit 6 makes the filter bed return amount Q1 in the daytime period larger than that in the night time period and makes the filter bed return amount Q1 in the night time period smaller than that in the daytime period. You may. In the example presented in FIG. 8, since the total amount of drainage W1 is large during the daytime and the total amount of drainage W1 is small during the nighttime, the control unit 6 returns the filter bed during the daytime. The processing capacity is improved by increasing the amount Q1. In other words, the control unit 6 increases the filter bed return amount Q1 in a time period in which the total amount of the drainage W1 increases and decreases the filter bed return amount Q1 in a time period in which the total amount of the drainage W1 decreases. Determine the amount of returned bed Q1. If the control unit 6 changes the filter bed return amount Q1 per hour in a day based on the information on the total amount change of the wastewater W1 in a day, the ratio is as shown in FIG. It is not limited to that shown in (the highest amount of filter bed return Q1 at 12:00 noon). In addition, the control unit 6 is not limited to previously setting the ratio, and may sequentially measure the flow rate of the wastewater W1 and sequentially change the filter bed return amount Q1 based on the measurement result.

制御部６は、１年のスパンでろ床返送量Ｑ１を制御してもよい。制御部６は、微生物の活動が抑制される冬にろ床返送量Ｑ１を高くし、微生物の活動が活発な夏にろ床返送量Ｑ１を低くしてもよい。すなわち、制御部６は、気温が低い場合は、ろ床返送量Ｑ１を高くし、気温が高い場合は、ろ床返送量Ｑ１を低くしてもよい。 The controller 6 may control the filter bed return amount Q1 in a span of one year. The control unit 6 may increase the filter bed return amount Q1 in the winter when the activity of the microorganisms is suppressed and decrease the filter bed return amount Q1 in the summer when the activity of the microorganisms is active. That is, the control unit 6 may increase the filter bed return amount Q1 when the temperature is low, and may decrease the filter bed return amount Q1 when the temperature is high.

制御部６は、ろ材充填層３３ｂの洗浄機能を実行した、すなわち逆洗浄を行った直後に、所定の時間だけ、ろ床返送量Ｑ１を高くしてもよい。この場合、所定の時間経過後には、ろ床返送量Ｑ１を元に戻す。逆洗浄を行った直後とは、逆洗浄が終了したタイミングのことをいうが、逆洗浄が終了したタイミングよりも所定の遅れ時間（例えば１０分）だけ遅れてもよい。また、所定の時間は、予め定められた時間であるが、例えば、１時間である。ろ材充填層３３ｂの逆洗浄を行った場合、ろ材３５表面の微生物も逆洗浄により剥がれ落ちる場合がある。制御部６は、逆洗浄の直後にろ床返送量Ｑ１を高くすることで、逆洗浄により減少した微生物の数を補填することができる。 The control unit 6 may increase the filter bed return amount Q1 for a predetermined time immediately after performing the cleaning function of the filter medium filling layer 33b, that is, immediately after performing the back cleaning. In this case, after the lapse of a predetermined time, the filter bed return amount Q1 is restored. Immediately after performing the backwash refers to the timing when the backwash ends, but may be delayed by a predetermined delay time (for example, 10 minutes) from the timing when the backwash ends. Further, the predetermined time is a predetermined time, for example, one hour. When the filter material-filled layer 33b is back-cleaned, the microorganisms on the surface of the filter material 35 may be peeled off by the back-cleaning. The control unit 6 can compensate the number of microorganisms reduced by the back washing by increasing the filter bed return amount Q1 immediately after the back washing.

制御部６は、例えば、ろ材充填層３３ｂにおける微生物量が十分であって、ろ材充填層３３ｂに微生物を返送する量を多くする必要がない場合には、固液分離返送量Ｑ２を増加させ、ろ床返送量Ｑ１を減少させてもよい。また、制御部６は、例えば、膜濃縮水Ｗ５中の微生物や固形物の濃度が所定値よりも高くなった場合にも、固液分離返送量Ｑ２を増加させ、ろ床返送量Ｑ１を減少させてもよい。固液分離部２における逆洗浄の頻度は、散水ろ床部３における逆洗浄の頻度よりも多い。例えば、固液分離部２における逆洗浄の頻度は、１時間に１回程度であり、散水ろ床部３における逆洗浄の頻度は、１週間に１回程度である。従って、以上説明したような場合に固液分離返送量Ｑ２を増やすことで、固液分離部２内に返送する膜濃縮水Ｗ５の量を増加させ、固液分離部２での逆洗浄により、膜濃縮水Ｗ５に含まれる不要な微生物や固形物等を、より早く外部に排出することが可能となる。また、この場合、膜ろ過部４にろ過膜４２の逆洗浄手段や、膜濃縮水Ｗ５の排出手段を設ける必要がなくなり、設備規模を小さくすることも可能となる。ただし、膜ろ過部４にも逆洗浄手段や排出手段を設けていてもよい。 For example, when the amount of microorganisms in the filter medium packed layer 33b is sufficient and it is not necessary to increase the amount of microorganisms returned to the filter medium packed layer 33b, the control unit 6 increases the solid-liquid separation returned amount Q2, The filter bed return amount Q1 may be decreased. The control unit 6 also increases the solid-liquid separation return amount Q2 and decreases the filter bed return amount Q1 when, for example, the concentration of microorganisms or solids in the membrane concentrated water W5 becomes higher than a predetermined value. You may let me. The frequency of backwashing in the solid-liquid separation unit 2 is higher than the frequency of backwashing in the sprinkling filter unit 3. For example, the frequency of backwashing in the solid-liquid separation unit 2 is about once per hour, and the frequency of backwashing in the sprinkling filter unit 3 is about once per week. Therefore, in the case as described above, by increasing the solid-liquid separation return amount Q2, the amount of the membrane concentrated water W5 returned into the solid-liquid separation unit 2 is increased, and by the back washing in the solid-liquid separation unit 2, Unwanted microorganisms, solids, etc. contained in the membrane concentrated water W5 can be discharged to the outside more quickly. Further, in this case, it is not necessary to provide the membrane filtration unit 4 with a backwashing means for the filtration membrane 42 or a means for discharging the membrane concentrated water W5, and the equipment scale can be reduced. However, the membrane filtration unit 4 may also be provided with a back washing means and a discharging means.

以上説明したように、第１実施形態に係る排水処理システム１は、散水ろ床部３と、膜ろ過部４と、散水ろ床接続管１７とを有する。散水ろ床部３は、微生物を担持させた複数のろ材３５を有するろ材充填層３３ｂを有する。散水ろ床部３は、ろ材充填層３３ｂの上部に処理用排水Ｗ２を散布してろ材充填層３３ｂ内に処理用排水Ｗ２を流下させ、微生物により処理用排水Ｗ２を生物処理して得た処理水Ｗ３を流出する。膜ろ過部４は、散水ろ床部の後段に設けられて、ろ過膜４２を有する。膜ろ過部４は、処理水Ｗ３を、ろ過膜４２を透過してない膜濃縮水Ｗ５と、ろ過膜４２を透過したろ過水Ｗ４とに分離する。散水ろ床接続管１７は、膜ろ過部４と散水ろ床部３とを接続し、膜濃縮水Ｗ５をろ材充填層３３ｂに返送する。 As described above, the wastewater treatment system 1 according to the first embodiment has the sprinkling filter section 3, the membrane filtering section 4, and the sprinkling filter connection pipe 17. The sprinkling filter part 3 has a filter medium filling layer 33b having a plurality of filter mediums 35 supporting microorganisms. The sprinkling filter part 3 is a treatment obtained by spraying the treatment wastewater W2 on the upper part of the filter medium filling layer 33b, causing the treatment wastewater W2 to flow down into the filter medium filling layer 33b, and biologically treating the treatment wastewater W2 with microorganisms. Water W3 flows out. The membrane filtration unit 4 is provided in a subsequent stage of the sprinkling filter unit and has a filtration membrane 42. The membrane filtration unit 4 separates the treated water W3 into membrane concentrated water W5 that has not permeated the filtration membrane 42 and filtered water W4 that has permeated the filtration membrane 42. The sprinkling filter connection pipe 17 connects the membrane filtering unit 4 and the sprinkling filter unit 3 and returns the membrane concentrated water W5 to the filter medium packed layer 33b.

排水処理システム１は、通気によって酸素を供給する散水ろ床部３を用いて生物処理を行っているため、曝気処理が必要ない。排水処理システム１は、曝気処理が必要ないので、消費電力を低減できる。そして、この排水処理システム１は、ろ材３５から微生物が剥がれ落ちた場合であっても、剥がれ落ちた微生物を含む膜濃縮水Ｗ５を、ろ材充填層３３ｂに返送する。従って、排水処理システム１は、剥がれ落ちた微生物をろ材充填層３３ｂに戻すことが可能となるため、ろ材３５表面の微生物の数の減少を抑制することができる。そのため、排水処理システム１は、微生物の減少による排水処理の性能低下を抑制することができる。 The wastewater treatment system 1 does not require aeration treatment because it performs biological treatment using the sprinkling filter unit 3 that supplies oxygen by aeration. Since the wastewater treatment system 1 does not require aeration treatment, power consumption can be reduced. Then, the wastewater treatment system 1 returns the membrane concentrated water W5 containing the detached microorganisms to the filter medium packed layer 33b even when the microorganisms are detached from the filter medium 35. Therefore, the wastewater treatment system 1 can return the separated microorganisms to the filter medium filling layer 33b, and can suppress the decrease in the number of microorganisms on the surface of the filter medium 35. Therefore, the wastewater treatment system 1 can suppress deterioration in performance of wastewater treatment due to reduction of microorganisms.

また、排水処理システム１は、水質測定部５と、制御部６とを有する。水質測定部５は、処理水Ｗ３又はろ過水Ｗ４の水質を測定する。制御部６は、水質測定部５の測定結果に基づき、ろ材充填層３３ｂへの膜濃縮水Ｗ５の返送量を決定する。排水処理システム１は、生物処理の後の水質（処理水Ｗ３又はろ過水Ｗ４の水質）を測定するため、散水ろ床部３における生物処理の処理能力を検出することができ、その検出結果に基づき、膜濃縮水Ｗ５の返送量、すなわち返送する微生物の量を決定する。従って、排水処理システム１は、生物処理の処理能力に基づき適量の膜濃縮水Ｗ５を返送することができるため、微生物の減少による排水処理の性能低下をより適切に抑制することができる。 The wastewater treatment system 1 also includes a water quality measuring unit 5 and a control unit 6. The water quality measuring unit 5 measures the water quality of the treated water W3 or the filtered water W4. The control unit 6 determines the return amount of the membrane concentrated water W5 to the filter medium filling layer 33b based on the measurement result of the water quality measuring unit 5. Since the wastewater treatment system 1 measures the water quality after the biological treatment (the quality of the treated water W3 or the filtered water W4), the treatment capacity of the biological treatment in the sprinkling filter part 3 can be detected, and the detection result can be obtained. Based on this, the return amount of the membrane concentrated water W5, that is, the amount of microorganisms to be returned is determined. Therefore, the wastewater treatment system 1 can return an appropriate amount of the membrane-concentrated water W5 based on the treatment capacity of biological treatment, so that the deterioration of wastewater treatment performance due to the reduction of microorganisms can be suppressed more appropriately.

水質測定部５は、処理水Ｗ３のアンモニア性窒素濃度、処理水Ｗ３の溶存酸素量、ろ過水Ｗ４のアンモニア性窒素濃度、及びろ過水Ｗ４の溶存酸素量のうち、少なくともいずれか１つを検出する。制御部６は、検出された処理水Ｗ３のアンモニア性窒素濃度、処理水Ｗ３の溶存酸素量、ろ過水Ｗ４のアンモニア性窒素濃度、及びろ過水Ｗ４の溶存酸素量のうち、少なくともいずれか１つに基づき、ろ材充填層３３ｂへの膜濃縮水Ｗ５の返送量を決定する。生物処理後におけるアンモニア性窒素濃度及び溶存酸素量は、生物処理の処理能力を示す指標となる。排水処理システム１は、生物処理の処理能力を示す指標となるアンモニア性窒素濃度、又は溶存酸素量に基づき膜濃縮水Ｗ５の返送量を決定するため、微生物の減少による排水処理の性能低下をより適切に抑制することができる。 The water quality measuring unit 5 detects at least one of the ammonia nitrogen concentration of the treated water W3, the dissolved oxygen amount of the treated water W3, the ammonia nitrogen concentration of the filtered water W4, and the dissolved oxygen amount of the filtered water W4. To do. The control unit 6 includes at least one of the detected ammonia nitrogen concentration of the treated water W3, the dissolved oxygen amount of the treated water W3, the ammonia nitrogen concentration of the filtered water W4, and the dissolved oxygen amount of the filtered water W4. Based on the above, the return amount of the membrane concentrated water W5 to the filter medium packed layer 33b is determined. The concentration of ammonia nitrogen and the amount of dissolved oxygen after the biological treatment are indicators of the treatment capacity of the biological treatment. The wastewater treatment system 1 determines the return amount of the membrane concentrated water W5 based on the ammonia nitrogen concentration, which is an index showing the treatment capacity of biological treatment, or the dissolved oxygen amount. It can be suppressed appropriately.

制御部６は、処理水Ｗ３又はろ過水Ｗ４のアンモニア性窒素濃度が所定濃度より高くなった場合、又は溶存酸素量が所定量より減少した場合に、ろ材充填層３３ｂへの膜濃縮水Ｗ５の返送量を増加させる。アンモニア性窒素濃度が高くなった場合、微生物が、アンモニア性窒素を十分に分解できていない可能性がある。また、溶存酸素量が減少した場合、ろ材充填層３３ｂにおける酸素量が減って、微生物が十分に生物処理を行うことができなくなっている可能性がある。制御部６は、このような場合に、膜濃縮水Ｗ５の返送量を増加させることで、微生物の減少による排水処理の性能低下をより適切に抑制することができる。 When the concentration of ammonia nitrogen in the treated water W3 or the filtered water W4 is higher than a predetermined concentration, or when the amount of dissolved oxygen is lower than a predetermined amount, the control unit 6 controls the concentration of the membrane concentrated water W5 to the filter medium packed layer 33b. Increase the amount returned. When the concentration of ammonia nitrogen is high, it is possible that the microorganism is not sufficiently decomposing ammonia nitrogen. Further, when the amount of dissolved oxygen decreases, the amount of oxygen in the filter medium packed layer 33b may decrease, and it may be impossible for the microorganisms to sufficiently perform biological treatment. In such a case, the control unit 6 can more appropriately suppress the deterioration of the performance of the wastewater treatment due to the decrease of microorganisms by increasing the return amount of the membrane concentrated water W5.

水質測定部５は、処理用排水Ｗ２の水質も測定する。そして、制御部６は、処理用排水Ｗ２と、処理水Ｗ３又はろ過水Ｗ４との間の水質の比較結果に基づき、ろ材充填層３３ｂへの膜濃縮水Ｗ５の返送量を決定する。排水処理システム１は、処理用排水Ｗ２と、処理水Ｗ３又はろ過水Ｗ４との間の水質の比較、すなわち、生物処理前後における水質を比較し、その比較結果に基づき、膜濃縮水Ｗ５の返送量を決定する。そのため、排水処理システム１は、生物処理の処理能力をより確実に検出することができ、微生物の減少による排水処理の性能低下をより適切に抑制することができる。 The water quality measuring unit 5 also measures the water quality of the treatment wastewater W2. Then, the control unit 6 determines the return amount of the membrane concentrated water W5 to the filter medium packed layer 33b, based on the comparison result of the water quality between the treatment wastewater W2 and the treated water W3 or the filtered water W4. The wastewater treatment system 1 compares the water quality between the treatment wastewater W2 and the treated water W3 or the filtered water W4, that is, compares the water quality before and after the biological treatment, and returns the membrane concentrated water W5 based on the comparison result. Determine the amount. Therefore, the wastewater treatment system 1 can more reliably detect the treatment capacity of the biological treatment, and can more appropriately suppress the deterioration of the performance of the wastewater treatment due to the reduction of microorganisms.

排水処理システム１は、固液分離部２と、固液分離接続管１８とを有する。固液分離部２は、散水ろ床部３よりも前段（すなわち処理用排水Ｗ２の流れの上流側）に設けられ、排水Ｗ１を固形成分と処理用排水Ｗ２とに分離する。固液分離接続管１８は、膜ろ過部４と固液分離部２とを接続し、膜濃縮水Ｗ５を固液分離部２に返送する。そして、制御部６は、水質測定部５の測定結果に基づき、ろ材充填層３３ｂと固液分離部２とへの膜濃縮水Ｗ５の返送量の割合を決定する。排水処理システム１は、水質の測定結果に基づき、ろ材充填層３３ｂと固液分離部２とへの膜濃縮水Ｗ５の返送量の割合を決定するため、ろ材充填層３３ｂへの膜濃縮水Ｗ５の提供量、すなわち微生物の提供量をより適切に調整することができる。 The wastewater treatment system 1 has a solid-liquid separation section 2 and a solid-liquid separation connection pipe 18. The solid-liquid separation unit 2 is provided at a stage before the sprinkling filter unit 3 (that is, on the upstream side of the flow of the treatment wastewater W2) and separates the wastewater W1 into a solid component and a treatment wastewater W2. The solid-liquid separation connection pipe 18 connects the membrane filtration unit 4 and the solid-liquid separation unit 2 and returns the membrane concentrated water W5 to the solid-liquid separation unit 2. Then, the control unit 6 determines the ratio of the amount of the membrane concentrated water W5 to be returned to the filter medium packed layer 33b and the solid-liquid separation unit 2 based on the measurement result of the water quality measurement unit 5. Since the wastewater treatment system 1 determines the ratio of the amount of the membrane concentrated water W5 returned to the filter medium packed layer 33b and the solid-liquid separation section 2 based on the water quality measurement result, the membrane concentrated water W5 to the filter medium packed layer 33b is determined. Can be adjusted more appropriately, that is, the amount of microorganisms provided.

水質測定部５は、処理水Ｗ３又はろ過水Ｗ４のアンモニア性窒素濃度、又は溶存酸素量を検出し、制御部６は、アンモニア性窒素濃度が所定濃度より高くなった場合、又は溶存酸素量が所定量より減少した場合に、ろ材充填層３３ｂへの膜濃縮水Ｗ５の返送量の割合を高くし、固液分離部２への膜濃縮水Ｗ５の返送量の割合を低くする。排水処理システム１は、アンモニア性窒素濃度の増加、又は溶存酸素量の減少など、生物処理が十分でないと判断した場合に、ろ材充填層３３ｂと固液分離部２とへの膜濃縮水Ｗ５の返送量の割合を決定するため、ろ材充填層３３ｂへの膜濃縮水Ｗ５の提供量、すなわち微生物の提供量をより適切に調整することができる。 The water quality measuring unit 5 detects the concentration of ammonia nitrogen in the treated water W3 or the filtered water W4, or the amount of dissolved oxygen, and the control unit 6 determines that the concentration of ammonia nitrogen is higher than a predetermined concentration or the amount of dissolved oxygen is When the amount is less than the predetermined amount, the proportion of the membrane concentrated water W5 returned to the filter medium packed layer 33b is increased, and the proportion of the membrane concentrated water W5 returned to the solid-liquid separation unit 2 is reduced. When the wastewater treatment system 1 determines that the biological treatment is not sufficient, such as an increase in the concentration of ammonia nitrogen or a decrease in the amount of dissolved oxygen, the membrane concentrated water W5 to the filter medium packed layer 33b and the solid-liquid separation unit 2 is not removed. In order to determine the ratio of the returned amount, the amount of the membrane concentrated water W5 provided to the filter medium packed layer 33b, that is, the amount of microorganisms provided can be adjusted more appropriately.

制御部６は、ろ材充填層３３ｂを逆洗浄した直後に、ろ材充填層３３ｂへの膜濃縮水Ｗ５の返送量を増加させる。ろ材充填層３３ｂを逆洗浄した場合、ろ材３５に付着した微生物が、逆洗浄により剥がれ落ちる場合がある。排水処理システム１は、そのような逆洗浄直後に膜濃縮水Ｗ５の返送量を増加することで、微生物の減少による排水処理の性能低下をより適切に抑制することができる。 The control unit 6 increases the amount of the membrane concentrated water W5 returned to the filter medium filling layer 33b immediately after backwashing the filter medium filling layer 33b. When the filter medium filling layer 33b is backwashed, the microorganisms attached to the filter medium 35 may be peeled off by the backwashing. The wastewater treatment system 1 increases the return amount of the membrane concentrated water W5 immediately after such backwashing, whereby it is possible to more appropriately suppress the deterioration of the performance of the wastewater treatment due to the reduction of microorganisms.

膜ろ過部４のろ過膜４２は、精密ろ過膜、又は限外ろ過膜である。ろ過膜４２が、精密ろ過膜、又は限外ろ過膜であることにより、微生物を確実に捕集することが可能となり、膜濃縮水Ｗ５の返送により、微生物を確実にろ材充填層３３ｂへ戻すことができる。 The filtration membrane 42 of the membrane filtration unit 4 is a microfiltration membrane or an ultrafiltration membrane. Since the filtration membrane 42 is a microfiltration membrane or an ultrafiltration membrane, it is possible to reliably collect the microorganisms, and by returning the membrane concentrated water W5, the microorganisms can be reliably returned to the filter medium packed layer 33b. You can

（第２実施形態）
次に、第２実施形態について説明する。第２実施形態に係る排水処理システム１Ａは、膜ろ過部がデッドエンド方式である点で、第１実施形態とは異なる。第２実施形態において、第１実施形態と構成が共通する箇所は、説明を省略する。 (Second embodiment)
Next, a second embodiment will be described. The wastewater treatment system 1A according to the second embodiment is different from the first embodiment in that the membrane filtration unit is a dead end system. In the second embodiment, the description of the parts having the same configuration as the first embodiment will be omitted.

図９は、第２実施形態に係る排水処理システムの概略構成を示すブロック図である。図９に示すように、排水処理システム１Ａは、膜ろ過部４Ａａ、４Ａｂ、４Ａｃと、バッファタンク部８と、を有する。また、散水ろ床部３と膜ろ過部４Ａａとは、処理水管１３ａで接続されており、散水ろ床部３と膜ろ過部４Ａｂとは、処理水管１３ｂで接続されており、散水ろ床部３と膜ろ過部４Ａｃとは、処理水管１３ｃで接続されている。膜ろ過部４Ａａ、４Ａｂ、４Ａｃは、並列に散水ろ床部３と接続されており、それぞれ処理水管１３ａ、１３ｂ、１３ｃから、処理水Ｗ３が供給される。 FIG. 9 is a block diagram showing a schematic configuration of the wastewater treatment system according to the second embodiment. As shown in FIG. 9, the wastewater treatment system 1A includes membrane filtration units 4Aa, 4Ab, 4Ac, and a buffer tank unit 8. Further, the sprinkling filter part 3 and the membrane filtering part 4Aa are connected by a treated water pipe 13a, and the sprinkling filter part 3 and the membrane filtering part 4Ab are connected by a treated water pipe 13b. 3 and the membrane filtration unit 4Ac are connected by a treated water pipe 13c. The membrane filtration units 4Aa, 4Ab, and 4Ac are connected in parallel to the sprinkling filter unit 3, and treated water W3 is supplied from treated water pipes 13a, 13b, and 13c, respectively.

膜ろ過部４Ａａとバッファタンク部８とは、膜濃縮水管１６ａで接続されており、膜ろ過部４Ａｂとバッファタンク部８とは、膜濃縮水管１６ｂで接続されており、膜ろ過部４Ａｃとバッファタンク部８とは、膜濃縮水管１６ｃで接続されている。膜ろ過部４Ａａ、４Ａｂ、４Ａｃは、並列にバッファタンク部８と接続されており、それぞれ膜濃縮水管１６ａ、１６ｂ、１６ｃを介して、バッファタンク部８に膜濃縮水Ｗ５を供給する。 The membrane filtration unit 4Aa and the buffer tank unit 8 are connected by a membrane concentrated water pipe 16a, the membrane filtration unit 4Ab and the buffer tank unit 8 are connected by a membrane concentrated water pipe 16b, and the membrane filtration unit 4Ac and the buffer are connected. The tank portion 8 is connected by a membrane concentrated water pipe 16c. The membrane filtration units 4Aa, 4Ab, and 4Ac are connected to the buffer tank unit 8 in parallel, and supply the membrane concentrated water W5 to the buffer tank unit 8 via the membrane concentrated water pipes 16a, 16b, and 16c, respectively.

膜ろ過部４Ａａ、４Ａｂ、４Ａｃは、それぞれデッドエンド方式のろ過膜４２Ａを有している点で、第１実施形態に係る膜ろ過部４とは異なる。膜ろ過部４Ａａ、４Ａｂ、４Ａｃは、図５に示すろ過膜４２の第２の端部４５が閉口した形状となっている。通常状態において、膜ろ過部４Ａａは、膜濃縮水管１６ａと接続されておらず、膜ろ過部４Ａｂは、膜濃縮水管１６ｂと接続されておらず、膜ろ過部４Ａｃは、膜濃縮水管１６ｃと接続されていない。通常状態とは、ろ過膜４２Ａに捕集された微生物を含む固形物を、膜ろ過部の外部に排出せず、ろ過処理、すなわちろ過水Ｗ４及び膜濃縮水Ｗ５の分離処理を行っている状態である。すなわち、通常状態においては、膜ろ過部４Ａａ、４Ａｂ、４Ａｃの内部には、ろ過膜４２Ａに捕集された微生物を含む固形物が、堆積される。膜ろ過部の数は３つに限られず、単数であってもよく、その数は任意である。以下、膜ろ過部４Ａａ、４Ａｂ、４Ａｃを区別しない場合は、膜ろ過部４Ａと記載する。同様に、膜濃縮水管１６ａ、１６ｂ、１６ｃを区別しない場合は、膜濃縮水管１６Ａと記載する。 The membrane filtration units 4Aa, 4Ab, and 4Ac are different from the membrane filtration unit 4 according to the first embodiment in that each has a dead end type filtration membrane 42A. The membrane filtration units 4Aa, 4Ab, and 4Ac have a shape in which the second end 45 of the filtration membrane 42 shown in FIG. 5 is closed. In the normal state, the membrane filtration unit 4Aa is not connected to the membrane concentrated water pipe 16a, the membrane filtration unit 4Ab is not connected to the membrane concentrated water pipe 16b, and the membrane filtration unit 4Ac is connected to the membrane concentrated water pipe 16c. It has not been. The normal state is a state in which the solid matter containing the microorganisms collected in the filtration membrane 42A is not discharged to the outside of the membrane filtration unit, but is filtered, that is, the filtered water W4 and the membrane concentrated water W5 are separated. Is. That is, in the normal state, the solid matter containing the microorganisms captured by the filtration membrane 42A is deposited inside the membrane filtration units 4Aa, 4Ab, 4Ac. The number of membrane filtration units is not limited to three, and may be a single number, and the number is arbitrary. Hereinafter, when the membrane filtration units 4Aa, 4Ab, and 4Ac are not distinguished, they are referred to as the membrane filtration unit 4A. Similarly, when the membrane concentrated water pipes 16a, 16b, and 16c are not distinguished, they are described as the membrane concentrated water pipe 16A.

例えば、堆積された固形物が所定量以上になった場合などに、制御部６は、排出状態に切り替えて、制御部６が、膜ろ過部４Ａと膜濃縮水管１６Ａとを接続する。このとき、堆積された固形物は、流入する処理水Ｗ３と共に、膜濃縮水Ｗ５として、膜濃縮水管１６Ａからバッファタンク部８に排出される。制御部６は、膜ろ過部４Ａが複数ある場合は、複数のうちの一部のみを排出状態とし、他を通常状態とすることで、排出処理を円滑に実行させる。 For example, when the amount of accumulated solids exceeds a predetermined amount, the control unit 6 switches to the discharge state, and the control unit 6 connects the membrane filtration unit 4A and the membrane concentrated water pipe 16A. At this time, the accumulated solid matter is discharged from the membrane concentrated water pipe 16A to the buffer tank section 8 as the membrane concentrated water W5 together with the inflowing treated water W3. When there are a plurality of membrane filtration units 4A, the control unit 6 causes only a part of the plurality of membrane filtration units 4A to be in the discharge state and the other to be in the normal state, thereby smoothly executing the discharge process.

バッファタンク部８は、膜ろ過部４Ａからの膜濃縮水Ｗ５を一時貯留する水槽である。バッファタンク部８は、膜濃縮水Ｗ５を一時貯留することで、例えば散水ろ床部３に急に多量の膜濃縮水Ｗ５が流入することを抑制するなど、膜濃縮水Ｗ５の返送におけるバッファ機能を有している。バッファタンク部８は、例えば排水管を有しており、制御部６の制御でその排水管から膜濃縮水Ｗ５を外部に排出することにより、内部の流量を一定に保っている。ただし、排水処理システム１Ａは、必ずしもバッファタンク部８を有していなくてもよい。 The buffer tank unit 8 is a water tank that temporarily stores the membrane concentrated water W5 from the membrane filtration unit 4A. The buffer tank unit 8 temporarily stores the membrane concentrated water W5, thereby suppressing a sudden flow of a large amount of the membrane concentrated water W5 into the sprinkling filter unit 3, for example, a buffer function in returning the membrane concentrated water W5. have. The buffer tank unit 8 has, for example, a drain pipe, and the control unit 6 controls the drain pipe to discharge the membrane concentrated water W5 to the outside, thereby keeping the internal flow rate constant. However, the wastewater treatment system 1A does not necessarily have to have the buffer tank unit 8.

第２実施形態における散水ろ床接続管１７と固液分離接続管１８とは、バッファタンク部８に接続されている以外は、第１実施形態と同じである。第２実施形態においては、膜濃縮水Ｗ５は、バッファタンク部８から、散水ろ床接続管１７と固液分離接続管１８とに分配され、固液分離部２と散水ろ床部３とに返送される。固液分離部２と散水ろ床部３とに返送する膜濃縮水Ｗ５の量の制御は、第１実施形態と同様である。 The sprinkling filter connection pipe 17 and the solid-liquid separation connection pipe 18 in the second embodiment are the same as those in the first embodiment except that they are connected to the buffer tank section 8. In the second embodiment, the membrane concentrated water W5 is distributed from the buffer tank part 8 to the sprinkling filter bed connecting pipe 17 and the solid-liquid separation connecting pipe 18, and to the solid-liquid separating part 2 and the sprinkling filter bed part 3. Will be returned. The control of the amount of the membrane concentrated water W5 returned to the solid-liquid separation unit 2 and the sprinkling filter unit 3 is the same as in the first embodiment.

以上、膜ろ過部４は、第１実施形態で説明したようにクロスフロー方式でもよく、第２実施形態で説明したようにデッドエンド方式であってもよい。いずれの場合においても、散水ろ床部３（ろ材充填層３３ｂ）に膜濃縮水Ｗ５を返送することができるため、微生物の減少による排水処理の性能低下を抑制することができる。 As described above, the membrane filtration unit 4 may be of the cross flow type as described in the first embodiment or may be of the dead end type as described in the second embodiment. In any case, since the membrane concentrated water W5 can be returned to the sprinkling filter part 3 (filter medium packed layer 33b), it is possible to suppress deterioration in performance of wastewater treatment due to a decrease in microorganisms.

（変形例）
次に、変形例について説明する。変形例に係る排水処理システム１Ｂは、膜濃縮水Ｗ５を、散水ろ床部３にのみ返送する点で、第１実施形態とは異なる。変形例において、第１実施形態と構成が共通する箇所は、説明を省略する。 (Modification)
Next, a modified example will be described. The wastewater treatment system 1B according to the modified example is different from the first embodiment in that the membrane concentrated water W5 is returned only to the sprinkling filter part 3. In the modified example, description of parts having the same configuration as the first embodiment will be omitted.

図１０は、変形例に係る排水処理システムの概略構成を示すブロック図である。図１０に示すように、排水処理システム１Ｂは、固液分離接続管１８を有さず、膜濃縮水Ｗ５を固液分離部２に返送しない。すなわち、排水処理システム１Ｂは、膜濃縮水Ｗ５を散水ろ床部３にのみ返送する。この場合、制御部６は、散水ろ床部３に返送する膜濃縮水Ｗ５の量（ろ床返送量Ｑ１）のみを制御する。このような場合においても、排水処理システム１Ｂは、散水ろ床部３（ろ材充填層３３ｂ）に膜濃縮水Ｗ５を返送することができるため、微生物の減少による排水処理の性能低下を抑制することができる。すなわち、排水処理システム１は、第１実施形態のように、固液分離部２及び散水ろ床部３の両方に膜濃縮水Ｗ５を返送してもよいし、変形例のように、散水ろ床部３のみに膜濃縮水Ｗ５を返送してもよい。 FIG. 10: is a block diagram which shows schematic structure of the wastewater treatment system which concerns on a modification. As shown in FIG. 10, the wastewater treatment system 1B does not have the solid-liquid separation connecting pipe 18, and does not return the membrane concentrated water W5 to the solid-liquid separation unit 2. That is, the wastewater treatment system 1B returns the membrane concentrated water W5 only to the sprinkling filter part 3. In this case, the control unit 6 controls only the amount of the membrane concentrated water W5 returned to the sprinkling filter unit 3 (filter bed return amount Q1). Even in such a case, the wastewater treatment system 1B can return the membrane concentrated water W5 to the sprinkling filter part 3 (filter medium packed layer 33b), and thus suppress the deterioration of the performance of the wastewater treatment due to the reduction of microorganisms. You can That is, the wastewater treatment system 1 may return the membrane concentrated water W5 to both the solid-liquid separation unit 2 and the sprinkling filter unit 3 as in the first embodiment, or as in the modified example, the sprinkling filter. The membrane concentrated water W5 may be returned only to the floor 3.

以上、本発明の実施形態及び変形例を説明したが、これら実施形態等の内容により実施形態が限定されるものではない。また、前述した構成要素には、当業者が容易に想定できるもの、実質的に同一のもの、いわゆる均等の範囲のものが含まれる。さらに、前述した構成要素は適宜組み合わせることが可能である。さらに、前述した実施形態等の要旨を逸脱しない範囲で構成要素の種々の省略、置換又は変更を行うことができる。 Although the embodiments and modifications of the present invention have been described above, the embodiments are not limited by the contents of these embodiments and the like. Further, the components described above include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those within the so-called equivalent range. Furthermore, the components described above can be combined appropriately. Furthermore, various omissions, replacements, or changes of the constituent elements can be made without departing from the scope of the above-described embodiments and the like.

１ 排水処理システム
２ 固液分離部
３ 散水ろ床部
４ 膜ろ過部
５ 水質測定部
６ 制御部
１１ 排水管
１２ 処理用排水管
１３ 処理水管
１４ ろ過水管
１６ 膜濃縮水管
１７ 散水ろ床接続管
１７ａ、１８ａ 膜濃縮水供給弁
１８ 固液分離接続管
３３ｂ ろ材充填層
３５ ろ材
４０ ろ過水槽
４２ ろ過膜
Ｑ１ ろ床返送量
Ｑ２ 固液分離返送量
Ｗ１ 排水
Ｗ２ 処理用排水
Ｗ３ 処理水
Ｗ４ ろ過水
Ｗ５ 膜濃縮水 1 Wastewater Treatment System 2 Solid-Liquid Separation Section 3 Sprinkling Filter Bed Section 4 Membrane Filtration Section 5 Water Quality Measuring Section 6 Control Section 11 Drain Pipe 12 Treatment Drain Pipe 13 Treated Water Pipe 14 Filtration Water Pipe 16 Membrane Concentrated Water Pipe 17 Sprinkling Filter Bed Connection Pipe 17a , 18a Membrane concentrated water supply valve 18 Solid-liquid separation connecting pipe 33b Filter medium packed bed 35 Filter medium 40 Filtration water tank 42 Filtration membrane Q1 Filter bed return quantity Q2 Solid-liquid separation return quantity W1 Wastewater W2 Treatment wastewater W3 Treated water W4 Filtrated water W5 membrane Concentrated water

Claims (6)

微生物を担持させた複数のろ材を有するろ材充填層を有し、前記ろ材充填層の上部に処理用排水を散布して前記ろ材充填層内に前記処理用排水を流下させ、前記微生物により前記処理用排水を生物処理して得た処理水を流出する散水ろ床部と、
ろ過膜を有し、前記散水ろ床部の後段に設けられて、前記処理水を、前記ろ過膜を透過してない膜濃縮水と、前記ろ過膜を透過したろ過水とに分離する膜ろ過部と、
前記膜ろ過部と前記散水ろ床部とを接続し、前記膜濃縮水を前記ろ材充填層に返送する散水ろ床接続管と、
前記処理水又は前記ろ過水の水質を測定する水質測定部と、
前記水質測定部の測定結果に基づき、前記ろ材充填層への前記膜濃縮水の返送量を決定する制御部と、を有し、
前記水質測定部は、前記処理水のアンモニア性窒素濃度、前記処理水の溶存酸素量、前記ろ過水のアンモニア性窒素濃度、及び前記ろ過水の溶存酸素量のうち、少なくともいずれか１つを検出し、前記制御部は、検出された前記処理水のアンモニア性窒素濃度、前記処理水の溶存酸素量、前記ろ過水のアンモニア性窒素濃度、及び前記ろ過水の溶存酸素量のうち、少なくともいずれか１つに基づき、前記ろ材充填層への前記膜濃縮水の返送量を決定し、
前記制御部は、前記アンモニア性窒素濃度が所定濃度より高くなった場合、又は前記溶存酸素量が所定量より減少した場合に、前記ろ材充填層への前記膜濃縮水の返送量を増加させる、排水処理システム。 Having a filter medium packed layer having a plurality of filter media supporting microorganisms, the treatment wastewater is sprinkled on the upper part of the filter medium packed layer to allow the treatment wastewater to flow down in the filter medium packed layer, and the treatment by the microorganisms. A sprinkling filter part for discharging treated water obtained by biologically treating industrial wastewater;
Membrane filtration that has a filtration membrane and is provided in the latter stage of the sprinkling filter section, and separates the treated water into membrane concentrated water that has not passed through the filtration membrane and filtration water that has passed through the filtration membrane. Department,
A sprinkling filter connecting pipe that connects the membrane filtering unit and the sprinkling filter unit and returns the membrane concentrated water to the filter medium packed bed,
A water quality measuring unit for measuring the water quality of the treated water or the filtered water,
Based on the measurement result of the water quality measurement unit, a control unit that determines the return amount of the membrane concentrated water to the filter medium packed layer,
The water quality measuring unit detects at least one of the ammonia nitrogen concentration of the treated water, the dissolved oxygen amount of the treated water, the ammonia nitrogen concentration of the filtered water, and the dissolved oxygen amount of the filtered water. Then, the control unit, at least one of the detected ammonia nitrogen concentration of the treated water, the dissolved oxygen amount of the treated water, the ammonia nitrogen concentration of the filtered water, and the dissolved oxygen amount of the filtered water. Based on one, determine the return amount of the membrane concentrated water to the filter medium packed bed,
The control unit, when the ammonia nitrogen concentration is higher than a predetermined concentration, or when the dissolved oxygen amount is lower than a predetermined amount, increases the return amount of the membrane concentrated water to the filter medium packed layer, Wastewater treatment system. 前記水質測定部は、前記処理用排水の水質も測定し、
前記制御部は、前記処理用排水と、前記処理水又は前記ろ過水との間の水質の比較結果に基づき、前記ろ材充填層への前記膜濃縮水の返送量を決定する、請求項１に記載の排水処理システム。 The water quality measuring unit also measures the water quality of the treatment wastewater,
The control unit determines an amount of the membrane-concentrated water to be returned to the filter medium-packed layer based on a comparison result of water quality between the treatment wastewater and the treated water or the filtered water. Wastewater treatment system described. 前記散水ろ床部よりも前段に設けられ、排水を固形成分と前記処理用排水とに分離する固液分離部と、
前記膜ろ過部と前記固液分離部とを接続し、前記膜濃縮水を前記固液分離部に返送する固液分離接続管と、をさらに有し、
前記制御部は、前記水質測定部の測定結果に基づき、前記ろ材充填層と前記固液分離部とへの前記膜濃縮水の返送量の割合を決定する、請求項１又は請求項２に記載の排水処理システム。 A solid-liquid separation unit that is provided in a stage before the sprinkling filter unit and separates wastewater into solid components and the treatment wastewater,
A solid-liquid separation connection pipe that connects the membrane filtration unit and the solid-liquid separation unit, and returns the membrane concentrated water to the solid-liquid separation unit,
The said control part determines the ratio of the return amount of the said membrane concentrated water to the said filter medium filling layer and the said solid-liquid separation part based on the measurement result of the said water quality measurement part, The claim 1 or claim 2 . Wastewater treatment system. 微生物を担持させた複数のろ材を有するろ材充填層を有し、前記ろ材充填層の上部に処理用排水を散布して前記ろ材充填層内に前記処理用排水を流下させ、前記微生物により前記処理用排水を生物処理して得た処理水を流出する散水ろ床部と、
ろ過膜を有し、前記散水ろ床部の後段に設けられて、前記処理水を、前記ろ過膜を透過してない膜濃縮水と、前記ろ過膜を透過したろ過水とに分離する膜ろ過部と、
前記膜ろ過部と前記散水ろ床部とを接続し、前記膜濃縮水を前記ろ材充填層に返送する散水ろ床接続管と、
前記処理水又は前記ろ過水の水質を測定する水質測定部と、
前記水質測定部の測定結果に基づき、前記ろ材充填層への前記膜濃縮水の返送量を決定する制御部と、を有し、
前記散水ろ床部よりも前段に設けられ、排水を固形成分と前記処理用排水とに分離する固液分離部と、
前記膜ろ過部と前記固液分離部とを接続し、前記膜濃縮水を前記固液分離部に返送する固液分離接続管と、をさらに有し、
前記制御部は、前記水質測定部の測定結果に基づき、前記ろ材充填層と前記固液分離部とへの前記膜濃縮水の返送量の割合を決定し、
前記水質測定部は、前記処理水又は前記ろ過水のアンモニア性窒素濃度、又は溶存酸素量を検出し、前記制御部は、前記アンモニア性窒素濃度が所定濃度より高くなった場合、又は前記溶存酸素量が所定量より減少した場合に、前記ろ材充填層への前記膜濃縮水の返送量の割合を高くし、前記固液分離部への前記膜濃縮水の返送量の割合を低くする、排水処理システム。 Having a filter medium packed layer having a plurality of filter media supporting microorganisms, the treatment wastewater is sprinkled on the upper part of the filter medium packed layer to allow the treatment wastewater to flow down in the filter medium packed layer, and the treatment by the microorganisms. A sprinkling filter part for discharging treated water obtained by biologically treating industrial wastewater;
Membrane filtration that has a filtration membrane and is provided in the subsequent stage of the sprinkling filter section, and separates the treated water into membrane concentrated water that has not passed through the filtration membrane and filtration water that has passed through the filtration membrane. Department,
A sprinkling filter connection pipe that connects the membrane filtration unit and the sprinkling filter unit and returns the membrane concentrated water to the filter medium packed bed,
A water quality measuring unit for measuring the water quality of the treated water or the filtered water,
Based on the measurement result of the water quality measurement unit, a control unit that determines the return amount of the membrane concentrated water to the filter medium packed bed,
A solid-liquid separation unit that is provided in a stage before the sprinkling filter unit and separates wastewater into solid components and the treatment wastewater,
A solid-liquid separation connection pipe that connects the membrane filtration unit and the solid-liquid separation unit, and returns the membrane concentrated water to the solid-liquid separation unit,
The control unit, based on the measurement result of the water quality measurement unit, determines the ratio of the amount of the membrane concentrated water returned to the filter medium packed layer and the solid-liquid separation unit,
The water quality measurement unit detects the concentration of ammonia nitrogen in the treated water or the filtered water, or the amount of dissolved oxygen, the control unit, when the concentration of ammonia nitrogen is higher than a predetermined concentration, or the dissolved oxygen When the amount is less than a predetermined amount, the ratio of the amount of the membrane concentrated water returned to the filter medium packed bed is increased, and the ratio of the amount of the membrane concentrated water returned to the solid-liquid separation unit is decreased, drainage Processing system. 前記制御部は、前記ろ材充填層を逆洗浄した直後に、前記ろ材充填層への前記膜濃縮水の返送量を増加させる、請求項１から請求項４のいずれか１項に記載の排水処理システム。 The wastewater treatment according to any one of claims 1 to 4 , wherein the control unit increases the return amount of the membrane concentrated water to the filter medium packed layer immediately after backwashing the filter medium packed layer. system. 前記ろ過膜は、精密ろ過膜、又は限外ろ過膜である、請求項１から請求項５のいずれか１項に記載の排水処理システム。 The wastewater treatment system according to any one of claims 1 to 5 , wherein the filtration membrane is a microfiltration membrane or an ultrafiltration membrane.
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