JP2022186452A - Renovation method of sewage treatment system and sewage treatment system - Google Patents

Renovation method of sewage treatment system and sewage treatment system Download PDF

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JP2022186452A
JP2022186452A JP2021094683A JP2021094683A JP2022186452A JP 2022186452 A JP2022186452 A JP 2022186452A JP 2021094683 A JP2021094683 A JP 2021094683A JP 2021094683 A JP2021094683 A JP 2021094683A JP 2022186452 A JP2022186452 A JP 2022186452A
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sewage
inflow
pond
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belt filter
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忠広 吉田
Tadahiro Yoshida
浩英 熊田
Hirohide Kumada
智之 井尻
Tomoyuki Ijiri
一輝 上海
Kazuki Jokai
明 石山
Akira Ishiyama
正毅 稲葉
Masaki Inaba
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Shinko Pantec Co Ltd
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Kobelco Eco Solutions Co Ltd
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Abstract

To provide a technology which deals with increase/decrease of a total amount of sewage water flowing into an influent water passage to recover a large amount of mud at high concentration efficiently in a sewage treatment system including primary sedimentation tanks.SOLUTION: Parts of multiple existing primary sedimentation tanks 10 are replaced with belt filters 20 which separate mud from sewage water flowing from an influent water passage 2 to an effluent water passage 4 by filtration, and parts of the multiple existing primary sedimentation tanks 10 are maintained as renovated primary sedimentation tanks 10. Sewage water flows from the influent water passage 2 into the renovated primary sedimentation tanks 10 and the belt filters 20 in a parallel state.SELECTED DRAWING: Figure 2

Description

本発明は、特に、流入水路から流出水路へ流れる下水から沈殿により汚泥を分離する最初沈殿池を備えた下水処理システムに関する。 More particularly, the present invention relates to a sewage treatment system with a primary sedimentation basin that separates sludge from sewage flowing from an inflow channel to an outflow channel by sedimentation.

従来の下水処理システムとして、流入水路から流出水路へ流れる下水から沈殿により汚泥を分離する複数の最初沈殿池を備えたものが知られている（例えば特許文献１を参照。）。このような下水処理システムに設けられた最初沈殿池は、一般的に、コンクリート躯体の構造物であって、沈砂池から流入水路を介して下水が連続的に流入され、その下水中の固形物が重力により底部へ沈降される。そして、固形物が除去された上澄み液は、越流トラフを超えて流出水路を介して反応タンクに排出されて生物処理される。一方、沈降した固形物は、汚泥掻き寄せ機により汚泥ピット集められて、ポンプ等により初沈汚泥として引き抜かれる。その引き抜かれた汚泥（以下「初沈汚泥」と呼ぶ場合がある。）は、濃縮機や脱水機等で固液分離され、焼却処分、またはメタン発酵処理の原料として利用される。 BACKGROUND ART As a conventional sewage treatment system, there is known one having a plurality of primary sedimentation tanks for separating sludge from sewage flowing from an inflow channel to an outflow channel by sedimentation (see, for example, Patent Document 1). The primary sedimentation tank provided in such a sewage treatment system is generally a structure with a concrete frame. will settle to the bottom by gravity. Then, the supernatant liquid from which the solid matter has been removed is discharged to the reaction tank through the overflow trough and the effluent channel, and is biologically treated. On the other hand, the sedimented solids are collected in a sludge pit by a sludge scraper and drawn out as primary sedimentation sludge by a pump or the like. The extracted sludge (hereinafter sometimes referred to as "initial sedimentation sludge") is solid-liquid separated by a thickener, a dehydrator, or the like, and is incinerated or used as a raw material for methane fermentation treatment.

特開２００５－３４７６３号公報JP-A-2005-34763

最初沈殿池は、固形物を沈殿により分離することから、流入水路から流出水路へ至る下水の滞留時間を一定以上（例えば約１時間～２時間程度）確保する必要がある。よって、下水の滞留時間を確保するために、処理可能な下水流量に対して比較的広い敷地面積が必要となる。また、降雨などにより流入水路への総下水流入量が増加する増水時においては、下水の滞留時間が短くなるため、初沈汚泥の回収効率が低下するという問題もある。更に、最初沈殿池において沈殿後に引き抜かれた初沈汚泥は、水分を多く含んで濃度が低い状態であるため、再度濃縮機や脱水機による固液分離操作が必須となる。
このような増水時においても十分な量の下水を処理するべく、特許文献１記載の下水処理システムでは、最初沈殿池とは別に高速ろ過池を設け、最初沈殿池と生物反応槽と最終沈殿池とを経由する下水処理フローとは別に、高速ろ過池を経由する下水処理フローで処理するように構成されている。しかしながら、この高速ろ過池は、最初沈殿池の代替として設けられたものではなく、増水分の下水を処理するためにのみ利用されるものであることから、増水時以外の定常時において汚泥の回収効率向上に寄与するものではない。また、高速ろ過池から逆洗排水として回収される汚泥は、最初沈殿池と同様、水分を多く含んで濃度が低い状態であるため、再度濃縮機や脱水機による固液分離操作が必須となる。
この実情に鑑み、本発明の主たる課題は、最初沈殿池を備えた下水処理システムにおいて、流入水路への総下水流入量の増減に対応して多くの汚泥を効率良く高濃度で回収する技術を提供する点にある。 Since the primary sedimentation tank separates solids by sedimentation, it is necessary to secure a retention time of sewage from the inflow channel to the outflow channel for a certain period or longer (for example, about 1 to 2 hours). Therefore, in order to ensure the retention time of sewage, a relatively large site area is required for the amount of sewage that can be treated. In addition, when the total amount of sewage inflow into the inflow channel increases due to rainfall or the like, the retention time of the sewage becomes shorter, and there is also the problem that the collection efficiency of the first settling sludge decreases. Furthermore, since the primary sedimentation sludge withdrawn after sedimentation in the primary sedimentation tank contains a large amount of water and has a low concentration, solid-liquid separation using a thickener or a dehydrator is essential.
In order to treat a sufficient amount of sewage even when the water level rises, in the sewage treatment system described in Patent Document 1, a high-speed filtration tank is provided separately from the primary sedimentation tank, and the primary sedimentation tank, the biological reaction tank, and the final sedimentation tank. Separately from the sewage treatment flow that passes through the high-speed filtration basin, it is configured to be treated by the sewage treatment flow that passes through. However, this high-speed filtration basin was not installed as a substitute for the primary sedimentation basin, but was used only to treat sewage with increased water content. It does not contribute to efficiency improvement. In addition, the sludge collected as backwash wastewater from the high-speed filtration basin contains a lot of water and has a low concentration, just like the primary sedimentation basin. .
In view of this situation, the main object of the present invention is to develop a technology for efficiently recovering a large amount of sludge at a high concentration in response to changes in the total amount of sewage inflow into the inflow channel in a sewage treatment system having a primary sedimentation tank. It is about providing.

本発明の第１特徴構成は、流入水路から流出水路へ流れる下水から沈殿により汚泥を分離する複数の既存最初沈殿池を備えた下水処理システムの改修方法であって、
前記複数の既存最初沈殿池の一部を、流入水路から流出水路へ流れる下水からろ過により汚泥を分離するベルトフィルタに置換すると共に、前記複数の既存最初沈殿池の一部を、改修後の最初沈殿池として維持し、
前記改修後の最初沈殿池及び前記ベルトフィルタに対して前記流入水路から並列状態で下水を流入させる点にある。 A first characteristic configuration of the present invention is a method for renovating a sewage treatment system having a plurality of existing primary sedimentation tanks for separating sludge from sewage flowing from an inflow channel to an outflow channel by sedimentation,
Replace a part of the plurality of existing primary sedimentation tanks with a belt filter that separates sludge from the sewage flowing from the inflow channel to the outflow channel by filtration, and replace a part of the plurality of existing primary sedimentation tanks with the first after the repair. maintained as a sedimentation pond,
Sewage is allowed to flow in parallel from the inflow channel into the primary sedimentation tank and the belt filter after repair.

本構成によれば、改修前の複数の既存最初沈殿池の一部が、改修により、下水から汚泥を分離可能で且つ水分が少ない高濃度の汚泥を回収可能なベルトフィルタに置換されるので、改修後の下水処理システムにおいて、多くの汚泥を効率良く高濃度で回収することができる。
更に、ベルトフィルタに置換されなかった最初沈殿池については、改修後最初沈殿池として維持して継続的に活用することにより、増水時などでも対応可能な処理能力を安定して発揮しながら、最初沈殿池に備えられた汚泥掻き寄せ機などの設備の劣化を防止することができる。そして、このような改修後の最初沈殿池をベルトフィルタと併用することで、当該最初沈殿池において流入水路から流出水路へ至る下水の滞留時間が比較的長くなるので、当該最初沈殿池における汚泥の回収効率を向上することができる。
従って、本発明により、複数の既存最初沈殿池を備えた下水処理システムの改修方法において、流入水路への総下水流入量の増減に対応して多くの汚泥を効率良く高濃度で回収することができる下水処理システムを合理的に構築する技術を提供することができる。 According to this configuration, some of the existing primary sedimentation tanks before repair are replaced with belt filters that can separate sludge from sewage and recover high-concentration sludge with low water content. In the sewage treatment system after renovation, a large amount of sludge can be efficiently collected with high concentration.
In addition, the primary sedimentation tank, which was not replaced with a belt filter, will be maintained as a primary sedimentation tank after renovation and will continue to be used. It is possible to prevent deterioration of equipment such as a sludge scraper provided in the sedimentation tank. By using such a primary sedimentation tank after renovation together with a belt filter, the retention time of sewage from the inflow channel to the outflow channel in the primary sedimentation tank becomes relatively long, so the sludge in the primary sedimentation tank Collection efficiency can be improved.
Therefore, according to the present invention, in a method for renovating a sewage treatment system having a plurality of existing primary sedimentation tanks, it is possible to efficiently collect a large amount of sludge at a high concentration corresponding to changes in the total amount of sewage inflow into the inflow channel. It is possible to provide a technology for rationally constructing a sewage treatment system that can be used.

本発明の第２特徴構成は、前記複数の既存最初沈殿池の一部を、下水を貯留可能な予備池とし、
前記ベルトフィルタの一次側の下水を前記予備池へ供給する予備池入水状態と、前記予備池の下水を前記ベルトフィルタの一次側へ供給する予備池出水状態と、を切替可能な予備池入出水手段と、
前記ベルトフィルタへの下水流入状態を検知する下水流入状態検知手段と、
前記下水流入状態検知手段の検知結果に基づいて前記予備池入出水手段を制御する予備池下水流入出制御を実行する制御手段と、を設ける点にある。 A second characteristic configuration of the present invention is that a part of the plurality of existing primary sedimentation tanks is a reserve tank capable of storing sewage,
A preliminary pond entry/exit state in which sewage on the primary side of the belt filter is supplied to the reserve pond and a preliminary pond exit state in which sewage is supplied to the primary side of the belt filter can be switched. means and
sewage inflow state detection means for detecting a state of sewage inflow into the belt filter;
and a control means for executing sewage inflow/outflow control for controlling the preliminary pond inflow/outflow means based on the detection result of the sewage inflow state detection means.

本構成によれば、ベルトフィルタを設置するにあたり、予備池が設けられて、制御手段により予備池入出水手段を制御する予備池下水流入出制御が実行される。このことで、例えば流入水路への総下水流入量が変動したり、ベルトフィルタの目詰まり状態の変動によってベルトフィルタへの下水の流入が増減したりする場合であっても、ベルトフィルタの一次側の下水を予備池へ供給して一時的に貯留させる予備池入水状態と、予備池の下水をベルトフィルタの一次側へ供給して返送する予備池出水状態とを適切に切り替える形態で、ベルトフィルタへの下水流入状態を常に適正な状態に保つことができる。即ち、流入水路への総下水流入量が増加する増水時においては、ベルトフィルタの一次側の下水を、流出水路側へ放出するのではなく、予備池入水状態に切り替えて、予備池へ供給して一時的に貯留することができる。すると、ベルトフィルタへの下水流入量の過剰な増加を抑制しながら、適正な量に制限された下水から高濃度の汚泥を回収することができる。一方、流入水路への総下水流入量が減少する減水時においては、予備池に貯留されている下水を、予備池出水状態に切り替えてベルトフィルタの一次側へ返送することができる。すると、ベルトフィルタへの下水流入量を適切な量に維持しながら、予備池から返送された分を加えて多くの下水から多くの汚泥を回収することができる。 According to this configuration, when the belt filter is installed, the preliminary pond is provided, and the preliminary pond sewage inflow/outflow control for controlling the preliminary pond inlet/outflow means is executed by the control means. As a result, for example, even if the total amount of sewage flowing into the inflow channel fluctuates or the amount of sewage flowing into the belt filter increases or decreases due to fluctuations in the clogging state of the belt filter, the primary side of the belt filter A state in which sewage is supplied to the reserve pond and is temporarily stored therein, and a state in which sewage is supplied to the reserve pond and returned to the primary side of the belt filter are properly switched. It is possible to keep the sewage inflow state to the appropriate state at all times. That is, when the water level rises when the total amount of sewage inflow into the inflow channel increases, the sewage on the primary side of the belt filter is not discharged to the outflow channel side, but is switched to the state of entering the reserve pond and supplied to the reserve pond. can be stored temporarily. As a result, high-concentration sludge can be recovered from sewage limited to an appropriate amount while suppressing an excessive increase in the amount of sewage flowing into the belt filter. On the other hand, when the total amount of sewage inflow into the inflow channel decreases, the sewage stored in the reserve reservoir can be switched to the reserve reservoir drain state and returned to the primary side of the belt filter. Then, a large amount of sludge can be recovered from a large amount of sewage by adding the amount returned from the reserve pond while maintaining the amount of sewage flowing into the belt filter at an appropriate amount.

本発明の第３特徴構成は、前記予備池入出水手段が、前記流入水路の下水を前記予備池へ導く予備池入水路の水流量を調整可能な予備池入水路ゲートと、前記予備池の下水を前記ベルトフィルタの一次側へ送出可能な返送ポンプとを有して構成されている点にある。 A third characteristic configuration of the present invention is characterized in that the preliminary pond inlet/outflow means is capable of adjusting a water flow rate of the preliminary pond inlet channel for guiding the sewage of the inflow channel to the preliminary pond, and a preliminary pond inlet channel gate. and a return pump capable of sending sewage to the primary side of the belt filter.

本構成によれば、予備池入出水手段において、返送ポンプを停止させながら予備池入水路ゲートを開放させる形態で予備池入水状態とし、予備池入水路ゲートを閉鎖させながら返送ポンプを作動させる形態で予備池出水状態とすることができる。 According to this configuration, in the spare pond entry/exit water means, the return pump is stopped and the reserve pond entry channel gate is opened to enter the reserve reservoir, and the return pump is operated while the reserve reservoir entry channel gate is closed. , it can be set to the reserve pond water discharge state.

本発明の第４特徴構成は、流入水路から流出水路へ流れる下水からろ過により汚泥を分離するベルトフィルタと、
流入水路から流出水路へ流れる下水から沈殿により汚泥を分離する最初沈殿池と、を備え、
前記最初沈殿池及び前記ベルトフィルタに対して前記流入水路から並列状態で下水を流入させる点にある。 A fourth characteristic configuration of the present invention is a belt filter that separates sludge from sewage flowing from an inflow channel to an outflow channel by filtering;
a primary sedimentation basin for separating sludge by sedimentation from sewage flowing from the inflow channel to the outflow channel;
The point is that sewage is allowed to flow in parallel from the inflow channel to the primary sedimentation tank and the belt filter.

本構成によれば、上記第１乃至第３特徴構成を有する本発明に係る下水処理システムの改修方法により構築される改修後の下水処理システムを提供することができる。そして、この構成により、これまで説明してきたものと作用効果を発揮して、入水路への総下水流入量が増加する増水時でも対応可能な処理能力を安定して発揮しながら効率良く高濃度の汚泥を回収することができる。 According to this configuration, it is possible to provide a sewage treatment system after refurbishment constructed by the sewage treatment system refurbishment method according to the present invention having the first to third characteristic configurations. With this configuration, the functions and effects described so far are exhibited, and even when the total amount of sewage inflow into the inflow channel increases, the treatment capacity that can be dealt with is stably exhibited, and the concentration is efficiently increased. of sludge can be collected.

既存下水処理システムの概略構成図Schematic diagram of existing sewage treatment system 改修後の下水処理システムの概略構成図Schematic diagram of sewage treatment system after renovation 図２に示す下水処理システムにおけるベルトフィルタ部分の断面図Cross-sectional view of the belt filter portion in the sewage treatment system shown in FIG. 図２に示す下水処理システムにおける予備池部分の断面図Cross-sectional view of the preliminary pond part in the sewage treatment system shown in FIG. 図２に示す下水処理システムにおける改修後の最初沈殿池部分の断面図Cross-sectional view of the primary sedimentation tank after renovation in the sewage treatment system shown in Figure 2

本発明の実施形態について図面に基づいて説明する。
図２に示す第１実施形態の下水処理システム１０１は、図１に示す既存の下水処理システム１００を改修して構築されたものである。 An embodiment of the present invention will be described based on the drawings.
A sewage treatment system 101 of the first embodiment shown in FIG. 2 is constructed by modifying the existing sewage treatment system 100 shown in FIG.

図１に示す既存の下水処理システム１００は、流入水路２から流出水路４へ流れる下水から沈殿により汚泥を分離する複数の既存最初沈殿池１０を備えたものとして構成されている。
このような既存の下水処理システム１００では、下水が沈砂池１から流入水路２を介して夫々の既存最初沈殿池１０に連続的に流入される。既存最初沈殿池１０では、図５に示すように、流入水路２から最初沈殿池入水路１０ｉを通じて流入した下水中の固形物（汚泥）が重力により底部１０ｄへ沈降され、固形物が除去された上澄み液が、越流トラフ１７を超えて最初沈殿池出水路１０ｏを通じて流出水路４に排出される。
そして、図１に示すように、流出水路４に排出された既存最初沈殿池１０の上澄み液は、生物反応槽５で生物処理された後に、最終沈殿池６及び消毒・放水部７を経て河川等に放出される。
一方、底部１０ｄに沈降した固形物（汚泥）は、掻き寄せ機（図示省略）等により回収される。この回収された汚泥は比較的多くの水分を含むため、再度濃縮機や脱水機による固液分離操作が施された後に、メタン発酵処理の原料等として好適に利用される。 The existing sewage treatment system 100 shown in FIG. 1 is configured with a plurality of existing primary sedimentation tanks 10 that separate sludge from sewage flowing from an influent channel 2 to an outflow channel 4 by sedimentation.
In such an existing sewage treatment system 100 , sewage is continuously fed from the settling basin 1 to each existing primary sedimentation basin 10 through the inflow channel 2 . In the existing primary sedimentation tank 10, as shown in FIG. 5, solids (sludge) in the sewage that flowed from the inflow channel 2 through the primary sedimentation tank inlet channel 10i were sedimented to the bottom 10d by gravity, and the solids were removed. The supernatant liquid passes over the overflow trough 17 and is discharged to the outflow channel 4 through the primary sedimentation tank outlet channel 10o.
Then, as shown in FIG. 1, the supernatant liquid of the existing primary sedimentation tank 10 discharged to the outflow channel 4 is biologically treated in the biological reaction tank 5, and then passed through the final sedimentation tank 6 and the disinfection/water discharge unit 7 to the river. Etc.
On the other hand, the solid matter (sludge) that settles on the bottom portion 10d is collected by a scraper (not shown) or the like. Since the recovered sludge contains a relatively large amount of water, it is preferably used as a raw material for methane fermentation treatment after being again subjected to solid-liquid separation using a thickener or a dehydrator.

本実施形態の下水処理システム１０１（図２参照）では、既存の下水処理システム１００（図１参照）を改修するにあたり、複数の既存最初沈殿池１０の一部が、流入水路２から流出水路４へ流れる下水からろ過により汚泥を分離するベルトフィルタ２０に置換されている。 In the sewage treatment system 101 (see FIG. 2) of the present embodiment, when the existing sewage treatment system 100 (see FIG. 1) is repaired, part of the plurality of existing primary sedimentation tanks 10 is changed from the inflow channel 2 to the outflow channel 4 It has been replaced by a belt filter 20 which separates the sludge from the sewage flowing into the sewer by filtration.

このベルトフィルタ２０は、図３に示すように、複数のローラ２６に支持された無端状のろ過ベルト２１を、一次側貯留部２２と二次側貯留部２３との境界部分に介装し、制御装置５０によりローラ２６を回転駆動させることにより、一次側貯留部２２に面するろ過ベルト２１の部分を汚泥排出部２７側へ送る形態で、ろ過ベルト２１を移動させる。
そして、一次側貯留部２２は、流入水路２に対してベルトフィルタ入水路２０ｉを介して接続されており、一方、二次側貯留部２３は、流出水路４に対してベルトフィルタ出水路２０ｏを介して接続されている。尚、既存最初沈殿池１０にて既に存在していた最初沈殿池入水路１０ｉがベルトフィルタ入水路２０ｉとして利用されており、既存最初沈殿池１０にて既に存在していた最初沈殿池出水路１０ｏがベルトフィルタ出水路２０ｏとして利用されている。 As shown in FIG. 3, the belt filter 20 has an endless filter belt 21 supported by a plurality of rollers 26 interposed at the boundary between the primary side storage section 22 and the secondary side storage section 23. By rotationally driving the roller 26 by the control device 50 , the filter belt 21 is moved in such a manner that the portion of the filter belt 21 facing the primary storage section 22 is sent to the sludge discharge section 27 side.
The primary reservoir 22 is connected to the inflow channel 2 via the belt filter inlet channel 20i, while the secondary reservoir 23 connects the belt filter outlet channel 20o to the outflow channel 4. connected through The primary sedimentation tank inlet channel 10i that already existed in the existing primary sedimentation tank 10 is used as the belt filter inlet channel 20i, and the primary sedimentation tank outlet channel 10o that already existed in the existing primary sedimentation tank 10 is used as the belt filter inlet channel 20i. is utilized as the belt filter water outlet passage 20o.

以上のように構成されたベルトフィルタ２０では、流入水路２からベルトフィルタ入水路２０ｉを通じて一次側貯留部２２に流入した下水中の固形物（汚泥）がろ過ベルト２１により除去され、当該ろ過ベルト２１を透過して二次側貯留部２３に供給されたろ過液がベルトフィルタ出水路２０ｏを通じて流出水路４に排出される。
一方、ろ過ベルト２１により除去された固形物（汚泥）は、ろ過ベルト２１の移動に伴って汚泥排出部２７に落下してスクリューコンベア等により回収される。このように回収された汚泥は、既存最初沈殿池１０（図５参照）で回収された汚泥と比べて、水分が少ない高濃度のものとなるので、メタン発酵処理の原料等として好適に利用することができる。また、ベルトフィルタ２０では、固形物が取り除かれたろ過ベルト２１が順次一次側貯留部２２と二次側貯留部２３との境界部分に移動されることにより、ろ過面の目詰まりが抑制されると共に、最初沈殿池１０（図５参照）のように沈殿等を待たずに下水から固形物を除去可能であるため、最初沈殿池１０よりも多くの下水（例えば２倍）から汚泥を分離する処理能力を有するものとなる。 In the belt filter 20 configured as described above, the solid matter (sludge) in the sewage flowing into the primary storage portion 22 from the inflow channel 2 through the belt filter inlet channel 20i is removed by the filtration belt 21, and the filtration belt 21 Filtrate supplied to the secondary reservoir 23 is discharged to the outflow channel 4 through the belt filter water outlet channel 20o.
On the other hand, the solids (sludge) removed by the filter belt 21 fall into the sludge discharge section 27 as the filter belt 21 moves and are collected by a screw conveyor or the like. The sludge collected in this way has less moisture and a higher concentration than the sludge collected in the existing primary sedimentation tank 10 (see FIG. 5), so it is suitably used as a raw material for methane fermentation treatment. be able to. In addition, in the belt filter 20, clogging of the filtering surface is suppressed by sequentially moving the filter belt 21 from which solid matter has been removed to the boundary portion between the primary storage portion 22 and the secondary storage portion 23. At the same time, since it is possible to remove solids from sewage without waiting for sedimentation etc. like the primary sedimentation tank 10 (see FIG. 5), it separates sludge from more sewage (eg, twice as much) than the primary sedimentation tank 10 It has processing power.

このベルトフィルタ２０の一次側貯留部２２には、一次側貯留部２２の水位を検知するベルトフィルタ一次側水位センサ２８（ベルトフィルタ一次側水位検知手段の一例）が設けられており、このベルトフィルタ一次側水位センサ２８の検知結果は制御装置５０に入力される。尚、このベルトフィルタ一次側水位センサ２８は、一次側貯留部２２の水位を検知するものであることから、ベルトフィルタ２０への下水流入状態を検知する下水流入状態検知手段Ｂであると言える。
更に、一次側貯留部２２の水位が上限界を超えた場合に、その上限界超の貯留下水を、オーバーフロー放出路３３を通じて後述する予備池３０に放出するオーバーフロー部２５が設けられている。 A belt filter primary water level sensor 28 (an example of belt filter primary water level detection means) for detecting the water level of the primary storage part 22 is provided in the primary storage part 22 of the belt filter 20. A detection result of the primary side water level sensor 28 is input to the control device 50 . Since the belt filter primary side water level sensor 28 detects the water level of the primary side reservoir 22 , it can be said that the belt filter 20 is sewage inflow state detection means B for detecting the state of sewage inflow into the belt filter 20 .
Furthermore, an overflow section 25 is provided to discharge the stored sewage exceeding the upper limit to a reserve pond 30 described later through an overflow discharge passage 33 when the water level of the primary storage section 22 exceeds the upper limit.

このように構成されたベルトフィルタ２０は、回収される固形物（汚泥）の水分含有量や下水の処理能力に応じて、ろ過ベルト２１の速度や傾斜角度等の運転条件を適宜設定することが望ましい。例えば、ろ過ベルト２１の速度を増加させる又はろ過ベルト２１の傾斜角度を小さくすると、できるだけ目詰まりが解消された広いろ過面で下水をろ過する状態となることから、多くの下水を処理できる処理量優先の運転モードとすることができる。一方、ろ過ベルト２１の速度を減少させる又はろ過ベルト２１の傾斜角度を大きくすると、できるだけ汚泥が積層した狭い面で下水をろ過する状態となることから、高濃度の汚泥を回収することができる汚泥濃度優先の運転モードとすることができる。
尚、本実施形態の下水処理システム１０１では、複数のベルトフィルタ２０が設けられており、これら複数のベルトフィルタ２０に対して流入水路２から並列状態で下水が流入されている。そして、このように複数のベルトフィルタ２０で下水を処理する場合には、総下水流入量などの状態に応じて、夫々のベルトフィルタ２０の運転モードを、同じものとしたり、個別に異ならせたり、順次切り替えるなど、適宜設定することができる。尚、本実施形態では、ベルトフィルタ２０を複数設けたが、このベルトフィルタ２０の設置数は適宜変更することができ、単数であっても構わない。 For the belt filter 20 configured in this manner, the operating conditions such as the speed and inclination angle of the filtration belt 21 can be appropriately set according to the water content of the collected solid matter (sludge) and the sewage treatment capacity. desirable. For example, when the speed of the filtration belt 21 is increased or the inclination angle of the filtration belt 21 is decreased, the sewage is filtered with a wide filtration surface where clogging is eliminated as much as possible, so a large amount of sewage can be treated. It can be a priority operation mode. On the other hand, when the speed of the filtration belt 21 is decreased or the inclination angle of the filtration belt 21 is increased, the sewage is filtered on the narrow surface where the sludge is stacked as much as possible, so that highly concentrated sludge can be recovered. A density-priority operation mode can be set.
In addition, in the sewage treatment system 101 of the present embodiment, a plurality of belt filters 20 are provided, and sewage flows into the plurality of belt filters 20 from the inflow channel 2 in parallel. When sewage is treated by a plurality of belt filters 20 in this way, the operation mode of each belt filter 20 can be made the same or different depending on the state of the total amount of sewage inflow. , sequential switching, etc., can be set as appropriate. In this embodiment, a plurality of belt filters 20 are provided.

本実施形態の下水処理システム１０１（図２参照）では、既存の下水処理システム１００（図１参照）を改修するにあたり、上述したベルトフィルタ２０に置換されない複数の既存最初沈殿池１０の一部が、下水を貯留可能な予備池３０として利用されている。 In the sewage treatment system 101 (see FIG. 2) of the present embodiment, when modifying the existing sewage treatment system 100 (see FIG. 1), some of the existing primary sedimentation tanks 10 that are not replaced with the belt filter 20 described above are , is utilized as a reserve pond 30 capable of storing sewage.

予備池３０は、図４に示すように、既存の最初沈殿池１０が略そのまま利用される。即ち、最初沈殿池入水路１０ｉが略そのままの状態で予備池入水路３０ｉとして利用され、越流トラフ１７及び最初沈殿池出水路１０ｏが略そのままの状態で越流トラフ３７及び予備池出水路３０ｏとして利用されている。
即ち、予備池３０では、越流トラフ３７で規定される放出用水位超の貯留下水が、当該越流トラフ３７を超えて予備池出水路３０ｏにオーバーフローされて、流出水路４に排出される。尚、既存の最初沈殿池１０には、汚泥掻き寄せ機（不図示）が設置されているが、予備池３０として活用する際には、汚泥掻き寄せ機を撤去しても良いし撤去しなくても良い。 As shown in FIG. 4, the existing primary sedimentation tank 10 is used substantially as it is for the preliminary tank 30 . That is, the primary sedimentation tank inlet channel 10i is used as a preliminary pond inlet channel 30i in a substantially unchanged state, and the overflow trough 17 and the primary sedimentation tank outlet channel 10o are used in a substantially unchanged state as the overflow trough 37 and the preliminary pond outlet channel 30o. is used as
That is, in the reserve pond 30 , the stored sewage exceeding the discharge water level defined by the overflow trough 37 overflows the overflow trough 37 into the reserve pond outlet channel 30 o and is discharged to the outflow channel 4 . A sludge scraper (not shown) is installed in the existing primary sedimentation tank 10, but when it is used as the reserve tank 30, the sludge scraper may or may not be removed. can be

予備池入水路３０ｉには、流入水路２の下水を予備池３０へ導く予備池入水路３０ｉの水流量を調整可能な予備池入水路ゲート３２が設けられており、制御装置５０は、予備池入水路ゲート３２の開閉動作を制御可能に構成されている。
更に、予備池３０には、予備池３０の貯留下水を、前述したベルトフィルタ２０の一次側（上流側）である流入水路２に返送路３４を通じて返送するための返送ポンプ３５が設けられている。 The reserve pond inlet channel 30i is provided with a reserve reservoir inlet channel gate 32 capable of adjusting the water flow rate of the reserve reservoir inlet channel 30i that guides the sewage of the inflow channel 2 to the reserve pond 30. The opening/closing operation of the water inlet gate 32 is configured to be controllable.
Furthermore, the reserve pond 30 is provided with a return pump 35 for returning the sewage stored in the reserve pond 30 to the inflow channel 2, which is the primary side (upstream side) of the belt filter 20, through the return channel 34. .

そして、予備池入水路ゲート３２と返送ポンプ３５とが、ベルトフィルタ２０の一次側（上流側）である流入水路２の下水を予備池３０へ供給する予備池入水状態と、予備池３０の下水をベルトフィルタ２０の一次側である流入水路２へ供給する予備池出水状態と、を切替可能な予備池入出水手段Ａとして機能する。即ち、制御装置５０は、返送ポンプ３５を停止させながら予備池入水路ゲート３２を開放させる形態で予備池入水状態とし、予備池入水路ゲート３２を閉鎖させながら返送ポンプ３５を作動させる形態で予備池出水状態とすることができる。尚、上記実施形態では、予備池入水状態における予備池３０への下水の流入元や、返送ポンプ３５による予備池３０からの下水の返送先を、流入水路２としたが、これら予備池３０における下水の流入元や返送先については、べルトフィルタ２０の一次側（上流側）であればよく、例えばベルトフィルタ２０の一次側貯留部２２や沈砂池１等としても構わない。
予備池３０には、当該予備池３０の水位を検知する予備池水位センサ３８（予備池水位検知手段の一例）が設けられており、この予備池水位センサ３８の検知結果は制御装置５０に入力される。 Then, the preliminary pond entrance water channel gate 32 and the return pump 35 supply the sewage of the inflow channel 2, which is the primary side (upstream side) of the belt filter 20, to the preliminary pond 30. to the inflow channel 2, which is the primary side of the belt filter 20. That is, the control device 50 enters the preliminary reservoir entry state by opening the preliminary reservoir entry channel gate 32 while stopping the return pump 35 , and operates the return pump 35 while closing the preliminary reservoir entry channel gate 32 . Pond water state can be set. In the above-described embodiment, the inflow channel 2 is used as the inflow source of the sewage into the reserve pond 30 when the reserve pond 30 enters the water, and the return destination of the sewage from the reserve pond 30 by the return pump 35. The inflow source and return destination of the sewage may be the primary side (upstream side) of the belt filter 20, for example, the primary storage section 22 of the belt filter 20, the settling basin 1, or the like.
The reserve pond 30 is provided with a reserve pond water level sensor 38 (an example of reserve pond water level detection means) for detecting the water level of the reserve pond 30 , and the detection result of the reserve pond water level sensor 38 is input to the control device 50 . be done.

尚、予備池入水路ゲート３２の開放と返送ポンプ３５の作動とを択一的に実行することにより、予備池入水状態と予備池入水状態との切り替えを行うように構成している。しかしながら、流入水路２から予備池３０への下水の供給と予備池３０から流入水路２への下水の供給とを同時に行いながら、予備池入水路ゲート３２の開度調整及び返送ポンプ３５の送水量調整による夫々の供給量の大小バランスの切り替えにより、予備池入水状態と予備池入水状態との切り替えを行っても構わない。 By alternatively executing the opening of the reserve reservoir inlet water channel gate 32 and the operation of the return pump 35, the state of entering the reserve reservoir and the state of entering the reserve reservoir are switched. However, while supplying sewage from the inflow channel 2 to the reserve reservoir 30 and supplying sewage from the reserve reservoir 30 to the inflow channel 2 at the same time, adjusting the opening of the reserve reservoir inlet channel gate 32 and the water supply amount of the return pump 35 It is also possible to switch between the state of entering water into the reserve reservoir and the state of entering water into the reserve reservoir by switching the balance between the supply amounts of the respective supplies by adjustment.

本実施形態の下水処理システム１０１（図２参照）では、既存の下水処理システム１００（図１参照）を改修するにあたり、上述したベルトフィルタ２０への置換や上述した予備池３０としての利用がされてない複数の既存最初沈殿池１０の少なくとも一部が、略そのままの形態で改修後においても最初沈殿池１０として維持されている。
改修後の最初沈殿池１０には、流入水路２の下水を最初沈殿池１０へ導く最初沈殿池入水路１０ｉの水流量を調整可能な最初沈殿池入水路ゲート１２が設けられており、制御装置５０は、最初沈殿池入水路ゲート１２の開閉動作を制御可能に構成されている。 In the sewage treatment system 101 (see FIG. 2) of the present embodiment, when the existing sewage treatment system 100 (see FIG. 1) is repaired, it is replaced with the belt filter 20 described above and used as the reserve pond 30 described above. At least a part of a plurality of existing primary sedimentation tanks 10 that are not installed are maintained as primary sedimentation tanks 10 in substantially the same form even after repair.
The primary sedimentation tank 10 after repair is provided with a primary sedimentation tank inlet channel gate 12 capable of adjusting the water flow rate of the primary sedimentation tank inlet channel 10i that guides sewage from the inflow channel 2 to the primary sedimentation tank 10, and a control device. 50 is configured to be able to control the opening/closing operation of the primary sedimentation tank inlet channel gate 12 .

そして、下水処理システム１０１では、最初沈殿池入水路ゲート１２が開放された状態において、最初沈殿池１０及びベルトフィルタ２０に対して流入水路２から並列状態で下水を流入させる。このことで、ベルトフィルタ２０に置換されず予備池３０としても利用されない最初沈殿池１０を改修後においても活用することができる。 In the sewage treatment system 101 , sewage flows in parallel from the inflow channel 2 into the primary sedimentation tank 10 and the belt filter 20 with the primary sedimentation tank inlet channel gate 12 open. As a result, the primary sedimentation tank 10, which is not replaced with the belt filter 20 and is not used as the reserve tank 30, can be utilized even after the repair.

本実施形態の下水処理システム１０１では、流入水路２への総下水流入量が増加してない定常時においては、最初沈殿池入水路ゲート１２が開放されており、流入水路２から最初沈殿池１０及びベルトフィルタ２０に対して並列状態で下水が流入され、当該最初沈殿池１０及びベルトフィルタ２０の双方で汚泥の分離処理が行われる。このことで、増水時などでも対応可能な処理能力が安定して発揮されると共に、最初沈殿池１０に備えられた汚泥掻き寄せ機などの設備が継続的に運転されることになって、当該設備の劣化が防止される。そして、このような改修後の最初沈殿池１０がベルトフィルタ２０と併用されるので、当該最初沈殿池１０において流入水路２から流出水路４へ至る下水の滞留時間が比較的長くなるので、当該最初沈殿池１０における汚泥の回収効率が向上される。尚、当該最初沈殿池１０における水理学的滞留時間（以下、ＨＲＴと称する）は、汚泥が沈降するのであれば特に制限はないが、既存のシステムで一般的な１～２時間よりも長い方が好ましく、より好ましいのは２～５時間、更に好ましいのは４～５時間である。更に、制限するものではないが、改修後の最初沈殿池１０における下水の滞留時間は、改修前の滞留時間と比べて、１．５倍以上とすることが好ましく、２倍以上更には２．５倍以上とすることがより好ましく、５倍以下とすることが好ましい。最初沈殿池１０における下水の滞留時間を長くすることで最初沈殿池１０での汚泥の回収量を高めることができる。一方で最初沈殿池１０における下水の滞留時間を所定時間以上保持しても汚泥の回収量は大きく変化しない。
更に、流入水路２への総下水流入量が減少している減水時においては、制御装置５０による自動制御などにより、最初沈殿池入水路ゲート１２を閉鎖することもできる。例えば、予備池水位センサ３８で検知される予備池３０の水位が所定の設定水位を下回った場合に、最初沈殿池入水路ゲート１２を閉鎖することで、全ての下水をベルトフィルタ２０により処理して、高濃度の汚泥を効率良く回収することができる。 In the sewage treatment system 101 of this embodiment, the primary sedimentation tank inlet channel gate 12 is open during a steady state when the total sewage inflow to the inflow channel 2 is not increasing, and the primary sedimentation tank 10 and the belt filter 20 in parallel, and the sludge is separated in both the primary sedimentation tank 10 and the belt filter 20 . As a result, the treatment capacity that can be handled even when the water level rises is stably exhibited, and the equipment such as the sludge scraper provided in the primary sedimentation tank 10 is continuously operated. Equipment deterioration is prevented. Since the primary sedimentation tank 10 after such repair is used together with the belt filter 20, the retention time of the sewage from the inflow channel 2 to the outflow channel 4 in the primary sedimentation tank 10 becomes relatively long. The sludge collection efficiency in the sedimentation tank 10 is improved. The hydraulic retention time (hereinafter referred to as HRT) in the primary sedimentation tank 10 is not particularly limited as long as the sludge settles, but it is longer than the 1 to 2 hours common in existing systems. is preferred, more preferably 2 to 5 hours, and still more preferably 4 to 5 hours. Furthermore, although not limited, the retention time of the sewage in the primary sedimentation tank 10 after repair is preferably 1.5 times or more, more than twice the retention time before repair, or 2 times or more. It is more preferable to make it 5 times or more, and it is preferable to make it 5 times or less. By lengthening the retention time of the sewage in the primary sedimentation tank 10, the amount of sludge collected in the primary sedimentation tank 10 can be increased. On the other hand, even if the retention time of the sewage in the primary sedimentation tank 10 is maintained for a predetermined time or longer, the amount of collected sludge does not change significantly.
Furthermore, when the total amount of sewage flowing into the inflow channel 2 is decreasing, the primary sedimentation tank inlet channel gate 12 can be closed by automatic control by the control device 50 or the like. For example, when the water level of the reserve pond 30 detected by the reserve pond water level sensor 38 falls below a predetermined set water level, the primary sedimentation tank inlet channel gate 12 is closed so that all the sewage is processed by the belt filter 20. Therefore, highly concentrated sludge can be recovered efficiently.

更に、流入水路２へ供給される総下水流入量を検知する総下水流入量検知手段９として、ポンプ場（図示省略）から沈砂池１に流入する下水流量を上記総下水流入量として測定する総下水流量測定器９ａが設けられている。尚、この総下水流入量検知手段９は、ベルトフィルタ２０に通じる流入水路２への総下水流入量を検知するものであることから、ベルトフィルタ２０への下水流入状態を検知する下水流入状態検知手段Ｂであると言える。
尚、総下水流量測定器９ａの設置個所は適宜変更可能であり、例えば沈砂池１の下水流出部側の流入水路２に設けることもできる。また、総下水流量測定器９ａの代わりに、沈砂池１の上流側にあるポンプ場の貯水槽水位に基づいて上記総下水流量を算出する手段や、天気予報の予報降水量に基づいて上記総下水流量を予測する手段等を、上記総下水流入量検知手段９として設けることもできる。 Furthermore, as a total sewage inflow detection means 9 for detecting the total sewage inflow supplied to the inflow channel 2, the total sewage inflow is measured as the total sewage inflow from the pumping station (not shown) into the settling basin 1. A sewage flow meter 9a is provided. Since the total sewage inflow detection means 9 detects the total sewage inflow into the inflow channel 2 leading to the belt filter 20, the sewage inflow state detection means detects the state of sewage inflow into the belt filter 20. It can be said that it is means B.
The installation position of the total sewage flow rate measuring device 9a can be changed as appropriate. Alternatively, instead of the total sewage flow rate measuring device 9a, means for calculating the total sewage flow rate based on the water level of the pumping station upstream of the settling basin 1, or the total Means for predicting the sewage flow rate can also be provided as the total sewage inflow detection means 9 .

本実施形態の下水処理システム１０１（図２参照）では、既存の下水処理システム１００（図１参照）を改修するにあたり、後述する予備池下水流入出制御を実行する制御装置５０（制御手段の一例）が設けられる。以下、これら制御の詳細について説明を加える。 In the sewage treatment system 101 (see FIG. 2) of the present embodiment, when the existing sewage treatment system 100 (see FIG. 1) is repaired, a control device 50 (an example of a control means) that executes the sewage inflow and outflow control of the preliminary pond described later ) is provided. Details of these controls will be described below.

（予備池下水流入出制御）
予備池下水流入出制御では、下水流入状態検知手段Ｂ（ベルトフィルタ一次側水位センサ２８、総下水流入量検知手段９）の検知結果に基づいて予備池入出水手段Ａ（予備池入水路ゲート３２、返送ポンプ３５）が制御されて、ベルトフィルタ２０への下水流入状態が常に適正な状態に保たれている。 (Preliminary pond sewage inflow/outflow control)
In the preliminary pond sewage inflow/outflow control, the preliminary pond inflow/outflow means A (the preliminary pond inflow channel gate 32 , the return pump 35) is controlled to keep the sewage flowing into the belt filter 20 in a proper state.

具体的に、予備池下水流入出制御において、ベルトフィルタ一次側水位センサ２８で検知されるベルトフィルタ２０の一次側貯留部２２の水位が予め設定された設定水位超である場合には、返送ポンプ３５を停止させながら予備池入水路ゲート３２を開放させる形態で予備池入水状態に切り替えられる。すると、ベルトフィルタ２０の一次側である流入水路２の下水が、流出水路４側へ放出されるのではなく、予備池入水路ゲート３２を通じて予備池３０へ供給されて一時的に貯留される。このことで、ベルトフィルタ２０への下水流入量の過剰な増加が抑制されて、ベルトフィルタ２０の一次側貯留部２２の水位の過剰な上昇が抑制され、適正な量に制限された下水から高濃度の汚泥が回収される。後に、ベルトフィルタ２０の一次側貯留部２２の水位が上記設定水位以下に低下した場合には、予備池下水流入出制御の実行により、予備池入水状態が終了される。このことで、予備池入水状態を維持することに伴うベルトフィルタ２０の一次側貯留部２２の水位の無用な低下が抑制され、効率良くベルトフィルタ２０により汚泥が回収される。
尚、予備池入水状態に切り替えるか否かの判断指標となるベルトフィルタ２０の一次側貯留部２２の上記設定水位は、ベルトフィルタ２０が効率良く作動できる上限界の水位として、一次側貯留部２２のオーバーフロー部２５の水位未満の範囲内で適宜設定することができる。また、予備池入水状態に切り替えるか否かの判断指標としてベルトフィルタ２０の一次側貯留部２２の水位に対して設定される上記設定水位は、予備池入水状態に切り替えられる第一設定水位と、予備池入水状態が終了となる、第一設定水位よりも低い水位である第二設定水位を設けて制御してもよい。 Specifically, in the preliminary pond sewage inflow/outflow control, when the water level of the primary storage portion 22 of the belt filter 20 detected by the belt filter primary side water level sensor 28 exceeds a preset set water level, the return pump 35 is stopped, the reserve pond entry waterway gate 32 is opened to switch to the reserve pond entry state. Then, the sewage in the inflow channel 2, which is the primary side of the belt filter 20, is not discharged to the outflow channel 4 side, but is supplied to the preliminary pond 30 through the preliminary pond inlet channel gate 32 and temporarily stored. As a result, an excessive increase in the amount of sewage flowing into the belt filter 20 is suppressed, an excessive rise in the water level in the primary storage section 22 of the belt filter 20 is suppressed, and the amount of sewage restricted to an appropriate amount is reduced to a high level. Concentrated sludge is recovered. Later, when the water level of the primary storage portion 22 of the belt filter 20 falls below the set water level, the auxiliary pond entering state is terminated by execution of the auxiliary pond sewage inflow/outflow control. As a result, unnecessary lowering of the water level of the primary storage portion 22 of the belt filter 20 caused by maintaining the state of entering the preliminary pond is suppressed, and sludge is efficiently collected by the belt filter 20 .
The set water level of the primary storage section 22 of the belt filter 20, which serves as a judgment index for determining whether or not to switch to the state of entering water into the reserve reservoir, is the upper limit water level at which the belt filter 20 can operate efficiently. can be appropriately set within a range of less than the water level of the overflow portion 25 of . Further, the set water level that is set for the water level of the primary storage portion 22 of the belt filter 20 as a judgment index for determining whether to switch to the state of entering water into the reserve reservoir is the first set water level at which the state is switched to the state of entering water into the reserve pond, A second set water level, which is a water level lower than the first set water level at which the state of entering the reserve reservoir ends, may be provided for control.

流入水路２への総下水流入量が増加する増水時において、上記のように予備池下水流入出制御の実行により予備池入水状態に切り替えられて流入水路２の下水が予備池３０へ供給されることに伴って、予備池３０の水位が上限界に近い放出用水位超となる場合がある。このような場合であっても、その放出用水位超の貯留下水は、越流トラフ３７を超えて最初沈殿池出水路１０ｏを通じて流出水路４へ放出されることになるので、予備池３０から周辺設備への漏洩が回避される。尚、最初沈殿池１０が複数存在する場合、放出用水位超の貯留下水を、ベルトフィルタ２０と併用運転していない別の最初沈殿池１０へ放出してもよい。 When the total amount of sewage inflow into the inflow channel 2 increases, the sewage in the inflow channel 2 is supplied to the reserve pond 30 by executing the sewage inflow/outflow control of the reserve pool as described above to switch to the state of entering the reserve reservoir. As a result, the water level of the reserve pond 30 may exceed the release water level, which is close to the upper limit. Even in such a case, the stored sewage exceeding the discharge water level will exceed the overflow trough 37 and be discharged to the outflow waterway 4 through the primary sedimentation tank outlet waterway 10o. Leakage to equipment is avoided. In addition, when there are a plurality of primary sedimentation tanks 10, the stored sewage exceeding the discharge water level may be discharged to another primary sedimentation tank 10 that is not operated together with the belt filter 20.

一方、予備池下水流入出制御において、総下水流入量検知手段９で検知される流入水路２への総下水流入量が設定総下水流入量以下である場合には、予備池入水路ゲート３２を閉鎖させながら返送ポンプ３５を作動させる形態で予備池出水状態に切り替えられる。すると、予備池３０の下水が返送ポンプ３５を通じてベルトフィルタ２０の一次側である流入水路２へ供給されて返送される。このことで、ベルトフィルタ２０への下水流入量が適切な量に維持されて、ベルトフィルタ２０の一次側貯留部２２の水位の過剰な低下が抑制され、予備池３０から返送された分を加えて多くの下水から多くの汚泥が回収される。後に、流入水路２への総下水流入量が設定総下水流入量超に増加した場合には、予備池下水流入出制御の実行により、予備池出水状態が終了される。このことで、予備池出水状態を維持することに伴うベルトフィルタ２０の一次側貯留部２２の水位の無用な上昇が抑制され、効率良くベルトフィルタにより汚泥を回収される。
尚、予備池出水状態に切り替えるか否かの判断指標となる流入水路２への総下水流入量の設定総下水流入量は、ベルトフィルタ２０が効率良く作動できる下限界の水位として適宜設定することができる。また、予備池出水状態に切り替えるか否かの判断指標として流入水路２への総下水流入量に対して設定される上記設定総下水流入量は、予備池出水状態に切り替えられる第一設定総下水流入量と、予備池出水状態が終了となる、第一設定総下水流入量よりも高い水量である第二設定総下水流入量を設けて制御してもよい。 On the other hand, in the preliminary pond sewage inflow/outflow control, when the total sewage inflow to the inflow channel 2 detected by the total sewage inflow detecting means 9 is equal to or less than the set total sewage inflow, the spare pond inlet channel gate 32 is turned on. It is possible to switch to the preliminary water discharge state by operating the return pump 35 while closing it. Then, the sewage of the preliminary pond 30 is supplied to the inflow channel 2, which is the primary side of the belt filter 20, through the return pump 35 and returned. As a result, the amount of sewage flowing into the belt filter 20 is maintained at an appropriate amount, an excessive decrease in the water level of the primary side reservoir 22 of the belt filter 20 is suppressed, and the amount returned from the reserve pond 30 is added. A large amount of sludge is recovered from a large amount of sewage water. Later, when the total sewage inflow into the inflow channel 2 exceeds the set total sewage inflow, the preliminary pond sewage inflow/outflow control is executed to terminate the preliminary pond outflow state. As a result, an unnecessary rise in the water level of the primary storage portion 22 of the belt filter 20 due to the maintenance of the preliminary water discharge state is suppressed, and sludge is efficiently collected by the belt filter.
The set total sewage inflow into the inflow channel 2, which is the index for determining whether or not to switch to the preliminary pond outflow state, is appropriately set as the lower limit water level at which the belt filter 20 can operate efficiently. can be done. Further, the set total sewage inflow amount set with respect to the total sewage inflow amount to the inflow channel 2 as a judgment index for determining whether to switch to the preliminary pond outflow state is the first set total sewage inflow amount to be switched to the preliminary pond outflow state. The inflow amount and the second set total sewage inflow amount, which is a water amount higher than the first set total sewage inflow amount at which the preliminary pond outflow state ends, may be provided and controlled.

〔別実施形態〕
本発明の他の実施形態について説明する。尚、以下に説明する各実施形態の構成は、それぞれ単独で適用することに限らず、他の実施形態の構成と組み合わせて適用することも可能である。 [Another embodiment]
Another embodiment of the present invention will be described. It should be noted that the configuration of each embodiment described below is not limited to being applied alone, and can be applied in combination with the configurations of other embodiments.

（１）上記実施形態では、既存の下水処理システム１００を改修するにあたり、ベルトフィルタ２０に置換されない複数の既存最初沈殿池１０の一部を、下水を貯留可能な予備池３０として利用したが、改修後の下水処理システム１０１において、予備池３０を設けないように構成しても構わない。 (1) In the above embodiment, when modifying the existing sewage treatment system 100, some of the plurality of existing primary sedimentation tanks 10 that are not replaced with the belt filter 20 are used as the reserve tank 30 capable of storing sewage. In the sewage treatment system 101 after repair, the preliminary pond 30 may be omitted.

（２）上記実施形態では、予備池入出水手段Ａとしての予備池入水路ゲート３２を開放することにより、ベルトフィルタ２０の一次側である流入水路２の下水を予備池３０へ供給する予備池入水状態としたが、例えば、この予備池入水路ゲート３２を常時閉鎖した場合であっても、ベルトフィルタ２０の一次側である一次側貯留部２２の上限界超の貯留下水がオーバーフロー部２５及びオーバーフロー放出路３３を通じて予備池３０に供給されることで、予備池入水状態としても構わない。 (2) In the above embodiment, by opening the preliminary pond inlet channel gate 32 as the preliminary pond inlet/outlet means A, the sewage in the inflow channel 2, which is the primary side of the belt filter 20, is supplied to the preliminary pond 30. Although it is in the state of entering water, for example, even if this spare pond inlet channel gate 32 is always closed, stored sewage exceeding the upper limit of the primary side storage section 22, which is the primary side of the belt filter 20, overflows into the overflow section 25 and By supplying to the reserve pond 30 through the overflow discharge path 33, the reserve pond entering state may be established.

（３）上記実施形態では、ベルトフィルタ一次側水位センサ２８を、ベルトフィルタ２０の一次側貯留部２２の水位を検知するものとして設置したが、このベルトフィルタ一次側水位センサ２８は、ベルトフィルタ２０の一次側の水位を検知するものであればよく、例えば流入水路２の水位を検知するものとして設置しても構わない。 (3) In the above embodiment, the belt filter primary side water level sensor 28 is installed to detect the water level of the belt filter 20 primary storage section 22 . Any device may be used as long as it detects the water level on the primary side of the .

２ 流入水路
４ 流出水路
９ 総下水流入量検知手段
９ａ 総下水流量測定器（総下水流入量検知手段）
１０ 最初沈殿池
１０ｉ 最初沈殿池入水路
１２ 最初沈殿池入水路ゲート
２０ ベルトフィルタ
２２ 一次側貯留部
２５ オーバーフロー部（予備池入出水手段）
２８ ベルトフィルタ一次側水位センサ（ベルトフィルタ一次側水位検知手段）
３０ 予備池
３０ｉ 予備池入水路
３０ｏ 予備池出水路
３２ 予備池入水路ゲート
３５ 返送ポンプ
３８ 予備池水位センサ（予備池水位検知手段）
５０ 制御装置（制御手段）
１００ 下水処理システム
１０１ 下水処理システム
Ａ 予備池入出水手段
Ｂ 下水流入状態検知手段 2 Inflow channel 4 Outflow channel 9 Total sewage inflow detection means 9a Total sewage flow rate measuring device (total sewage inflow detection means)
10 primary sedimentation tank 10i primary sedimentation tank inlet water channel 12 primary sedimentation tank inlet water channel gate 20 belt filter 22 primary side storage section 25 overflow section (preliminary pond inlet/outlet means)
28 belt filter primary side water level sensor (belt filter primary side water level detection means)
30 Reserve pond 30i Reserve pond inlet channel 30o Reserve pond outlet channel 32 Reserve pond inlet channel gate 35 Return pump 38 Reserve pond water level sensor (reserve pond water level detection means)
50 control device (control means)
100 Sewage treatment system 101 Sewage treatment system A Spare pond inlet/outlet means B Sewage inflow state detection means

Claims (4)

流入水路から流出水路へ流れる下水から沈殿により汚泥を分離する複数の既存最初沈殿池を備えた下水処理システムの改修方法であって、
前記複数の既存最初沈殿池の一部を、流入水路から流出水路へ流れる下水からろ過により汚泥を分離するベルトフィルタに置換すると共に、前記複数の既存最初沈殿池の一部を、改修後の最初沈殿池として維持し、
前記改修後の最初沈殿池及び前記ベルトフィルタに対して前記流入水路から並列状態で下水を流入させる下水処理システムの改修方法。 A method of retrofitting a sewage treatment system having a plurality of existing primary sedimentation basins for separating sludge by sedimentation from sewage flowing from an inflow channel to an outflow channel, comprising:
Replace a part of the plurality of existing primary sedimentation tanks with a belt filter that separates sludge from the sewage flowing from the inflow channel to the outflow channel by filtration, and replace a part of the plurality of existing primary sedimentation tanks with the first after the repair. maintained as a sedimentation pond,
A method for renovating a sewage treatment system in which sewage flows in parallel from the inflow channel into the primary sedimentation tank and the belt filter after refurbishment. 前記複数の既存最初沈殿池の一部を、下水を貯留可能な予備池とし、
前記ベルトフィルタの一次側の下水を前記予備池へ供給する予備池入水状態と、前記予備池の下水を前記ベルトフィルタの一次側へ供給する予備池出水状態と、を切替可能な予備池入出水手段と、
前記ベルトフィルタへの下水流入状態を検知する下水流入状態検知手段と、
前記下水流入状態検知手段の検知結果に基づいて前記予備池入出水手段を制御する予備池下水流入出制御を実行する制御手段と、を設ける請求項１に記載の下水処理システムの改修方法。 A part of the plurality of existing primary sedimentation tanks is used as a reserve tank capable of storing sewage,
A preliminary pond entry/exit state in which sewage on the primary side of the belt filter is supplied to the reserve pond and a preliminary pond exit state in which sewage is supplied to the primary side of the belt filter can be switched. means and
sewage inflow state detection means for detecting a state of sewage inflow into the belt filter;
2. The method of repairing a sewage treatment system according to claim 1, further comprising control means for executing sewage inflow/outflow control for controlling said preliminary pond inflow/outflow means based on the detection result of said sewage inflow state detection means. 前記予備池入出水手段が、前記流入水路の下水を前記予備池へ導く予備池入水路の水流量を調整可能な予備池入水路ゲートと、前記予備池の下水を前記ベルトフィルタの一次側へ送出可能な返送ポンプとを有して構成されている請求項２に記載の下水処理システムの改修方法。 The preliminary pond inlet/outflow means has a preliminary pond inlet channel gate capable of adjusting a water flow rate of the preliminary pond inlet channel for guiding the sewage from the inflow channel to the preliminary pond, and the sewage from the spare pool to the primary side of the belt filter. 3. A sewage treatment system refurbishment method according to claim 2, comprising a pumpable return pump. 流入水路から流出水路へ流れる下水からろ過により汚泥を分離するベルトフィルタと、
流入水路から流出水路へ流れる下水から沈殿により汚泥を分離する最初沈殿池と、を備え、
前記最初沈殿池及び前記ベルトフィルタに対して前記流入水路から並列状態で下水を流入させる下水処理システム。 a belt filter for filtering sludge from sewage flowing from an inflow channel to an outflow channel;
a primary sedimentation basin for separating sludge by sedimentation from sewage flowing from the inflow channel to the outflow channel;
A sewage treatment system in which sewage flows in parallel from the inflow channel to the primary sedimentation tank and the belt filter.
JP2021094683A 2021-06-04 2021-06-04 Renovation method of sewage treatment system and sewage treatment system Pending JP2022186452A (en)

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