JP3771870B2 - Sewage treatment system by oxidation ditch method - Google Patents

Sewage treatment system by oxidation ditch method Download PDF

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JP3771870B2
JP3771870B2 JP2002145355A JP2002145355A JP3771870B2 JP 3771870 B2 JP3771870 B2 JP 3771870B2 JP 2002145355 A JP2002145355 A JP 2002145355A JP 2002145355 A JP2002145355 A JP 2002145355A JP 3771870 B2 JP3771870 B2 JP 3771870B2
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sewage
sludge
excess sludge
aeration
aerobic
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JP2003334593A (en
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好雄 堺
正六 川内
克明 河野
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サーンエンジニアリング株式会社
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00Technologies for wastewater treatment
    • Y02W10/10Biological treatment of water, waste water, or sewage

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  • Accessories For Mixers (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)
  • Activated Sludge Processes (AREA)
  • Aeration Devices For Treatment Of Activated Polluted Sludge (AREA)
  • Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
  • Treatment Of Sludge (AREA)
  • Filtration Of Liquid (AREA)

Description

【0001】
【発明の属する技術分野】
本発明は、オキシデーションディッチ法による汚水処理システムに関するものである。
【0002】
【発明の背景】
オキシデーションディッチ(以下「OD」と略称する)法による脱窒処理システムとしては、無終端循環水路内を好気処理領域と無酸素処理領域とに区画するゾーン形成運転方式のものと、無終端循環水路内をこれに設けた曝気攪拌装置の間欠運転により経時的に好気状態と無酸素状態とに変化させる間欠曝気運転方式のものとが周知である。しかし、前者のものは、水路容積が必要以上に大型化するため、汚水処理場が小規模化する傾向にある近時においては実用性に乏しい。一方、後者のものでは、無終端循環水路全域を好気領域及び無酸素領域とするため、汚水処理場の小規模化にも対応することができるが、曝気攪拌装置の停止により無酸素状態を確保するため、無酸素状態において汚泥の沈殿,堆積を防止できず、活性汚泥と汚水の不均一な混合による処理効率低下を招く。
【0003】
そこで、従来からも、かかる問題を解決した汚水処理システムとして、図8に示す如く、長円形の反応槽(OD槽)101内に隔壁110を配置して無終端循環水路111を形成し、無終端循環水路111の両端部に回転数制御可能な縦軸型の曝気攪拌装置102,102を設けて、両曝気攪拌装置102,102を間欠的に高低速運転させることにより、無終端循環水路111の全域を好気状態と無酸素状態とに交互に保持するように構成されたもの(以下「従来システムS」という)が提案されている。かかる従来システムSによれば、曝気攪拌装置102,102の高速運転により、流入汚水106と活性汚泥との混合液106Aを曝気攪拌しつつ循環流動させて、好気処理たる硝化処理を行い、曝気攪拌装置102,102の低速運転により、混合液を曝気させることなく循環流動させて、汚泥の沈降を防止しつつ無酸素処理たる脱窒処理を行うのであり、上記した問題を生じることなく硝化脱窒処理を行うことができる。すなわち、好気運転(高速運転)においては、活性汚泥に含まれる好気性菌である硝化菌によりアンモニア性窒素が硝化され(NH+2O→NO +H+HO)、無酸素運転(低速運転)においては、活性汚泥中に硝化菌と混在する通性嫌気性菌である脱窒菌により硝酸性窒素を脱窒する(2NO +10H→N+4HO+2OH)。而して、硝化脱窒処理された混合液(処理混合液)160は、反応槽101から沈殿池115に溢流排出され、沈殿池115から処理水(上澄水)160aとして放流される。また、沈殿池115において処理水160aと分離(沈降分離)された汚泥(返送汚泥)160bは反応槽101に返送され、その一部は余剰汚泥161として処理系外に排出される。なお、余剰汚泥161は脱水機141により脱水されて、固形分(脱水汚泥)161aとして処理され、固形分161aから分離された液分(分離液)161bは反応槽101に返送される。
【0004】
しかし、従来システムSにあっては、無酸素状態においても曝気攪拌装置102,102を低速とはいえ回転駆動させるため、曝気攪拌装置102,102による混合液106Aの攪拌により汚水表面において空気(酸素)の取り込み量は減少しても若干の空気(酸素)は取り込まれ、適正な無酸素状態を確保できず、無酸素処理たる脱窒処理を効果的に行い得ないといった問題がある。また、曝気攪拌装置102,102を適正な無酸素状態を確保できる程度に低速運転させると、混合液106Aの流動が充分に行われず、無酸素状態における汚泥沈降を防止することができない。
【0005】
ところで、活性汚泥が余剰汚泥及び最終沈殿池流出水(処理水)中のSSとして処理系外に排出されるまでの反応槽内での平均滞留時間を示すSRT(Solids Retention Time)は、活性汚泥微生物の増殖と密接な関連があり、反応槽内で微生物が増殖するためには、SRTと微生物の比増殖速度μ(1/日)との間にμ>1/SRTの関係が存することが必要である。このように、SRTは活性汚泥微生物(有機物除去細菌,硝化細菌等)を始め、処理に障害を与える糸状細菌や放線菌がタンク内で増殖できるか否かを判断する上で重要な指標である。すなわち、活性汚泥法では、SRTを設定すると、その処理系内で増殖可能な微生物種が決まることから、SRTから処理水質を予測することが可能であり、SRTを制御することで活性汚泥を構成する微生物中のある特定機能をもつ微生物の活用や抑制が可能となる。而して、生物学的窒素除去を目的とする硝化脱窒処理を行うOD法においては、反応槽内が無酸素状態と好気状態とに変化することから、SRTの制御を行う上で徴生物の増殖を考慮する必要があるが、有機物除去に関与する細菌の増殖速度は硝化細菌より著しく速いため、硝化細菌が増殖できるASRT(Aerobic Solids Retention Time)が確保されていれば有機物は問題なく除去できると考えられる。したがって、OD法による汚水処理システムの運転制御を行う上では、硝化細菌の増殖に必要な条件を満たすSRT、つまり好気状態におけるSRT(ASRT)を確保することが必要である。
【0006】
ところで、完全硝化を達成するために必要なASRTは、水温(平均最低水温)Tをパラメータとして決定できることが経験的に知られており、処理条件に応じて次のような実験式(I)又は(II)から算出される。
【0007】
すなわち、流入汚水量の日間変動比(時間最大汚水量/日平均汚水量)が大きい(変動比2.7程度)の条件下で「処理水NH−N:1mg/L以下」を達成するために必要なASRTは、
ASRT≧40.7exp(−0.101・T)……(I)
で得られ、流入水量の日間変動比の比較的小さい(変動比2.2程度)の条件下で「処理水NH−N:1mg/L以下」を達成するために必要なASRTは、
ASRT≧29.7exp(−0.102・T)……(II)
で得られる。
【0008】
一方、ASRTを長くすることは硝化細菌の増殖にとって有利な条件ではあるが、低負荷や無負荷における必要以上の曝気は硝化細菌を減少させ、硝化速度の低下を招くことになるから、基質の供給速度が長い周期で大幅に変動する場合には、負荷に見合った余剰汚泥の引き抜きと好気条件の調整を行うことが必要である。硝化細菌は、供給される窒素負荷の濃度に関係なく一定の比増殖速度μで増殖し、最終的には供給される負荷に見合った量にまで達するから、窒素負荷によって硝化細菌の菌体量は変化し、負荷が高い程、菌体量は増加する。硝化細菌活性汚泥中に均一に分布し保持されていると考えられ、余剰汚泥量から決定されるASRTを水温に応じて硝化細菌の増殖に必要なレベルに保持すれば、常時、完全硝化を達成することができる。流入負荷が一定の場合は、発生する余剰汚泥量も一定であり、余剰汚泥により系外に引き抜かれる硝化細菌量は流入負荷に対する増殖分のみとなり、系内には常に一定の硝化細菌量が保持されるが、流入負荷が変動する場合では、余剰汚泥量もこれにともなって変化し、さらに硝化細菌の増殖量も増減することから,系内に一定の硝化細菌量を保持するためには、流入負荷に見合った余剰汚泥量の引き抜きが不可欠となる。
【0009】
そこで、従来システムSにあっても、このようなASRTを制御する場合において、流入負荷に対して適切な槽内汚泥量を定めて管理すべき槽内汚泥濃度を算出し、この算出された汚泥濃度に応じて沈殿池115から適量の余剰汚泥161を引き抜くようにしている。
【0010】
しかし、余剰汚泥濃度は沈殿池115からの返送汚泥160bと同一であるため、流入汚水量の変動や汚泥の沈降速度に大きく影響されることになる。その結果、余剰汚泥濃度が大きく変動して、ASRTを適正に維持することが困難である。また、その制御(ASRT制御)も高度の熟練を必要とし、OD法による汚水処理を効率良く適正に行うことが極めて困難である。
【0011】
【発明の概要】
本発明は、このような問題を生じることなく、OD法による汚水処理を効率よく効果的に行いうる汚水処理システムを提供することを目的とする。
【0012】
本発明は、上記の目的を達成すべく創作されたものであり、請求項1の発明は、汚水と活性汚泥との混合水を循環させる無終端循環水路と、当該水路内の所定量の混合水を定速回転により循環流動させると共に曝気攪拌させる曝気攪拌装置と、前記水路内の混合水中に水没させた定速回転をするプロペラにより所定量の混合水を循環流動させる水中プロペラ装置と、前記無終端循環水路内から余剰汚泥を引き抜く余剰汚泥引抜装置と曝気攪拌装置と水中プロペラ装置とを交互に発停制御すると共に余剰汚泥引抜装置を発停制御する制御装置とを具備し、曝気攪拌装置により混合水の循環流動と曝気攪拌が行われる好気運転と、水中プロペラ装置により混合水の循環流動のみが行われる無酸素運転とを交互に繰り返すことにより、無終端循環水路の全域を好気状態と無酸素状態とに交互に保持すると共に、余剰汚泥引抜装置を定期的に所定時間運転する構成とした汚水処理装置において、前記水中プロペラ装置を、そのプロペラの上端が混合水の水面に対して少なくとも50cmの深さとなるように位置させ、また前記制御装置を、前記各装置の運転を制御する制御器とデータ入力や演算結果を表示するタッチパネルとを備え、無終端循環水路の容量であるディッチ容量、計画流入汚水量、流水汚水SS濃度、流入SS当り汚泥発生率及び余剰汚泥引抜装置の汚泥引抜性能を含む基本条件データと、流量計からの汚水流入量、温度計からの流入汚水の最低水温及びMLSS計からの無終端循環水路内のMLSS濃度を含む運転条件データとが入力され、当該基本条件データ及び運転条件データから、前記好気運転と無酸素運転を交互に繰り返す24時間を単位とするタイムサイクルパターンの繰り返しサイクル数と、1サイクル中の好気運転時間及び無酸素運転時間と余剰汚泥引抜量とを演算し、当該演算値に基づいて前記曝気攪拌装置と水中プロペラ装置と余剰汚泥引抜装置の発停制御を自動又は手動により行うと共に、前記無終端循環水路内の混合水を常時0.25m/sec以上の平均流動速度で循環流動させるようにしたことを発明の基本構成とするものである。
【0013】
かかる汚水処理システムの好ましい実施の形態にあって、余剰汚泥引抜装置は、無終端循環水路から余剰汚泥を引き抜く余剰汚泥引抜ポンプと、該ポンプにより引き抜いた余剰汚泥を固液分離する固液分離機とを具備して、固液分離機により分離された液分を当該無終端循環水路に返戻するように構成されたものである。固液分離機としては、多重円板外胴型スクリュープレス脱水機を使用することが好ましい。
【0014】
また、制御装置は、流入汚水の最低温度に基づいて設定される好気状態における汚泥滞留時間を維持するように、曝気攪拌装置、水中プロペラ装置及び余剰汚泥引抜装置を発停制御するものであり、具体的には、当該システムに固有の基本条件データと当該システムの運転条件に応じて決定される運転条件データとから、好気運転及び無酸素運転の運転時間及び運転サイクル並びに余剰汚泥の引抜量を演算して、その演算値に基づいて曝気攪拌装置及び水中プロペラ装置並びに余剰汚泥引抜装置を発停制御するものである。ここに、基本条件データは、無終端循環水路の容量であるディッチ容量(VA(m))、計画流入汚水量(Qd(m/日))、流入汚泥SS濃度(Xi(mg/L))及び流入SS当たり汚泥発生率(α)及び余剰汚泥引抜装置(余剰汚泥引抜ポンプ)の汚泥引抜性能(qw(m/時))であり、運転条件データは、流入汚水量(Qi(m/日))、流入汚水の最低水温(T(℃))及び無終端循環水路内のMLSS濃度(ディッチ内MLSS濃度(XA(mg/L))である。かかる制御装置にあっては、曝気攪拌装置及び水中プロペラ装置の発停制御と余剰汚泥引抜装置の発停制御とを相互に関連することなく独立して行うことができる。また、制御装置は、各種データの入力操作を行うためのタッチパネルを具備するものであることが好ましい。
【0015】
また、水中プロペラ装置は、そのプロペラが無終端循環水路内における混合液の水面に対して少なくとも50cmの深さに位置されるように、配設されたものであることが好ましい。また、水中プロペラ装置は、曝気攪拌装置の停止期間中において、混合液を曝気することなく且つ当該混合液中の汚泥を沈降させない流速で循環流動させるべく、プロペラを低速回転させるものであることが好ましい。具体的には、水中プロペラ装置が、プロペラを20〜500rpmで回転させることにより、混合液を0.25m/sec以上の流速で循環流動させるものであることが好ましい。
【0016】
また、曝気攪拌装置は、鉛直線回りで回転する曝気攪拌翼を有する縦軸型のものであり、水中プロペラ装置が、そのプロペラを無終端循環水路の直線部分であって当該曝気攪拌翼の下流側部分に位置させたものであることが好ましい。また、無終端循環水路には、通常、曝気攪拌装置及び水中プロペラ装置が1台づつ設けられるが、ディッチ(無終端循環水路)が処理水量の多い大型のものである等、システムの構成条件によっては、曝気攪拌装置及び/又は水中プロペラ装置を複数台設けることも可能である。
【0017】
【発明の実施の形態】
図1〜図3は本発明の第1の実施の形態を示すもので、この実施の形態における本発明に係る汚水処理システム(以下「第1汚水処理システム」という)S1は、反応槽(OD槽)1と、反応槽1に配設された各1台の曝気攪拌装置2及び水中プロペラ装置3と、反応槽1から余剰汚泥を排出する余剰汚泥引き抜き装置4と、これらの装置2,3,4を発停制御する制御装置5とを具備する。なお、以下の説明においては、便宜上、前後とは図1、図2、図6及び図7における左右をいい、左右とは図1、図6及び図7における上下をいうものとする。
【0018】
反応槽1は、図1及び図2に示す如く、水平面形状が前後方向に長尺な長円形状をなし、左右中央部に前後方向に延びる隔壁10により無終端循環水路11を形成したものである。反応槽1の周壁適所には、無終端循環水路11に開口する流入出口12,13が設けられている。流入口12には、汚水供給源(図示せず)から導かれた給水路14が接続されていて、被処理水である汚水6が流入口12から無終端循環水路11に供給されるようになっている。流出口13には、沈殿池(最終沈殿池)15へと導かれた排水路16が接続されていて、反応槽1により処理(硝化脱窒素処理)された処理混合液60を沈殿池15において処理水60aと汚泥(活性汚泥)60bとに分離するようになっている。沈殿池15で汚泥60bを沈降分離された処理水60aは、沈殿池15から所定の排水系(図示せず)に溢流排出されるようになっている。一方、沈降汚泥(返送汚泥)60bは、沈殿池15の底部から返送路17を介して反応槽1つまり無終端循環水路11に返送されるようになっている。なお、流入出口12,13は、流入口12から無終端循環水路11に流入された汚水6がそのまま流出口13へとショートパスしないことを条件として、無終端循環水路11における任意個所に設けておくことができる。
【0019】
曝気攪拌装置2は、図1及び図2に示す如く、無終端循環水路11の前端部位に配置された縦軸型のエアレータであり、隔壁10の前端近傍位において曝気攪拌翼20,21を一定方向(図1の矢印方向)に回転させることにより、無終端循環水路11において汚水6と活性汚泥6aとの混合液6Aを循環流動させると共に曝気攪拌するように構成されている。曝気攪拌翼は、鉛直回転軸22の下端部に放射状に取り付けられた縦羽根20…と各隣接縦羽根20,20間に傾斜状に取り付けられた横羽根21…とからなり、鉛直回転軸22を減速機(変速機)付の駆動モータ(図示せず)により回転駆動させると、混合液6Aを攪拌しつつ吸引,揚水して曝気させると共に、旋回流を形成して混合液6Aを無終端循環水路11内において循環流動させるものである。なお、曝気攪拌装置2が設けられない無終端循環水路11の後端部位には、円弧状の整流壁18が設けられている。
【0020】
水中プロペラ装置3は、図1及び図2に示す如く、無終端循環水路11の直線部分の適所(例えば、前後方向中央部位)において混合液6Aに水没させた状態で配置されたプロペラ30を具備するものであり、曝気攪拌装置2の停止期間(後述する無酸素運転期間)中において、混合液6Aを曝気することなく且つ混合液6A中の汚泥を沈降させない流速で循環流動させるべく、プロペラ30を低速回転させるように構成されている。この例では、水中プロペラ装置3は、プロペラを20〜500rpmで回転させることにより、混合液6Aを0.25m/sec以上の流速で循環流動させるように構成されている。また、プロペラ30の鉛直方向位置は、混合液6Aの水面からの深さ(混合液6Aの水面からプラペラ30の上端部までの深さ)Dが50cm以上となるように設定されている。
【0021】
余剰汚泥引き抜き装置4は、反応槽1に接続された余剰汚泥引き抜き路40と、余剰汚泥引き抜き路40が導かれた固液分離機41と、余剰汚泥引き抜き路40に介設された余剰汚泥引抜ポンプ42と、固液分離機41から反応槽1に導かれた分離液返送路43と、固液分離機41から所定の汚泥処理設備(図示せず)に導かれた脱水汚泥排出路44とを具備して、余剰汚泥61を余剰汚泥引抜ポンプ42により反応槽1から引き抜いて固液分離機41において固液分離し、固形分たる脱水汚泥61aを脱水汚泥排出路44から汚泥処理設備に排出させると共に液分たる分離液61bを分離液返送路43から反応槽1つまり無終端循環水路11に返送させるようになっている。余剰汚泥引抜ポンプ42としては、後述する如く設定される日余剰汚泥引抜量(Qwa(m/日))の余剰汚泥61を定量的に引き抜きうるに必要且つ充分な性能を有するスラリポンプ等が使用される。固液分離機41としては、反応槽1内の低濃度MLSS(余剰汚泥61)を直接且つ充分に脱水処理できる脱水機が使用されるが、一般には、多重円板外胴型スクリュープレス脱水機を使用することが好ましい。なお、固液分離機41は、余剰汚泥引抜ポンプ42と同期して作動されるようになっている。
【0022】
制御装置5は、図1に示す如く、曝気攪拌装置2、水中プロペラ装置3及び余剰汚泥引き抜き装置4を制御する制御器50と、この制御器50へのデータ入力等を行うためのタッチパネル51とを具備する。タッチパネル51には、各データ及び演算結果を入力,表示するための画面、動作モード(自動制御運転及び手動運転)を設定するための画面、運転状況(各装置2,3,4の運転時間,運転経過時間等)をリアルタイムで表示する画面及び手動運転を行うための操作画面等が含まれる。
【0023】
制御器50は、図3に示す如く、流入汚水6の最低温度(T(℃))に基づいて設定される好気状態における汚泥滞留時間(ASRT(日))を維持するように、曝気攪拌装置2、水中プロペラ装置3及び余剰汚泥引抜装置4を発停制御するものであり、当該システムS1に固有の基本条件データと当該システムS1の運転条件に応じて決定される運転条件データとから、少なくとも好気・無酸素繰り返しサイクル(f(回/日))、1サイクル好気時間(toc(h/サイクル))、1サイクル無酸素時間(taoc(h/サイクル))及び余剰汚泥引抜時間(tq(h/日))を演算して、その演算値に基づいて上記各装置2,3,4を発停制御するものである。ここに、基本条件データは、無終端循環水路11の容量であるディッチ容量(VA(m))、計画流入汚水量(Qd(m/日))、流入汚水SS濃度(Xi(mg/L))、流入SS当たり汚泥発生率(α)及び余剰汚泥引抜装置4つまり余剰汚泥引抜ポンプ42の汚泥引抜性能(qw(m/h))であり、当該システムS1の構成,設置場所等により固定的に設定することができるものである。また、運転条件データは、無終端循環水路11への汚水6の流入量である流入汚水量(Qi(m/日))、流入汚水6の最低水温(T(℃))及び無終端循環水路11内の混合液6AのMLSS濃度(XA(mg/L))であり、当該システムS1の運転状況(四季やシステム設置場所の周辺環境の変化等)によって変動する可能性の高いものである。
【0024】
而して、制御器50によれば、図3に示す制御フローに従って、次のような演算及び各装置2,3,4の運転制御が行われる。なお、この例では、各装置2,3,4を自動制御する他、必要に応じて、手動によっても制御できるように工夫されている。
【0025】
まず、タッチパネル51に基本条件データの入力画面(以下「基本条件設定画面」という)を表示させて、基本条件データ(1)〜(5)を入力する。
(1)ディッチ容量:VA(m
(2)計画流入汚水量:Qd(m/日)
(3)流入汚水SS濃度:Xi(mg/L)
(4)流入SS当たり汚泥発生率:α
(5)余剰汚泥ポンプ性能:qw(m/h)
【0026】
次に、タッチパネル51の表示画面を変更させて、運転条件データの入力画面(以下「運転条件入力画面」という)を表示させて、運転条件データ(6)〜(8)を入力する。
(6)流入汚水量:Qi(m3/日)
(7)最低水温:T(℃)
(8)ディッチ内MLSS濃度:XA(mg/L)
【0027】
データ(1)〜(8)が入力されると、制御器50による演算が開始され、次のような演算結果(9)〜(15)が得られる。
(9)ASRT:ASRT(日)
(10)SRT:SRT(日)
(11)日余剰汚泥引抜量:Qwa(m3/日)
(12)余剰汚泥引抜時間:tq(h/日)
(13)好気・無酸素繰り返しサイクル数:f(回/日)
(14)1サイクル好気時間:toc(h/サイクル)
(15)1サイクル無酸素時間:tac(h/サイクル)
【0028】
演算内容は、次の通りである。なお、ASRTについては、冒頭で述べた実験式(I)又は(II)が使用されるが、この例では、実験式(I)を使用している。また、Rは負荷率(計画流入汚水量(最大流入汚水量)Qwaに対する実流入汚水量qwの割合)であり、好気・無酸素繰り返しサイクル数(1日当たりの好気・無酸素運転の繰り返し回数)fは負荷率Rに基づいて決定される。一般に、fは1〜6の範囲でRの大きさに応じて決定され、Rが大きくなるに従いfの値は大きくなる。また、toTは日合計好気時間(h)であり、taTは日合計無酸素時間(h)である。
【0029】
ASRT=40.7・exp(−0.101・T)
SRT=2・ASRT
Qwd=VA/SRT
R=Qi/Qd
Qwa=Qwa
tq=Qwa/qw
toT=24・ASRT・Qi・Xi・α/(XA・VA)
taT=24−toT
toc=toT/f
tac=taT/f
【0030】
而して、上記した演算により演算結果(9)〜(15)が得られると、これらがタッチパネル51の運転条件設定画面に表示される。この運転条件条件設定画面には、運転条件データ(6)〜(8)の入力値も表示される。作業者は、これらの表示値(6)〜(15)を確認した上で、タッチパネル51の動作モード設定画面において、自動制御を行うか否かを選択する。自動制御動作OFFを選択すると、各装置2,3,4を手動操作にて運転させることができ、自動制御動作ONを選択すると、各装置2,3,4が制御器50により演算結果(9)〜(15)に基づいて次のように自動制御運転される。なお、手動運転においては、作業者が演算結果(9)〜(15)に基づいて各装置2,3,4を操作する。また、運転条件設定画面における表示値(特に、運転条件データ(6)〜(8)の入力値)を変更,修正する必要がある場合には、図3に示す如く、修正値を入力する。また、自動運転又は手動運転が開始された後において、動作モード又は運転条件(6)〜(8)を変更する必要が生じた場合には、その変更をタッチパネル51により行う。
【0031】
自動制御運転においては、曝気攪拌装置2と水中プロペラ装置3とが、演算結果(13)〜(15)により決定されるタイムサイクルパターン(例えば、図4又は図5に示すタイムサイクルパターン)で交互に発停制御される。
【0032】
而して、曝気攪拌装置2が駆動される好気運転においては、無終端循環水路11内において汚水6と活性汚泥6aとの混合液6Aが循環流動されると共に曝気攪拌が行われて、無終端循環水路11の全域が好気状態に保持され、好気性菌により汚水6中の有機性物質が分解されると共に汚水6に含まれていたアンモニア性窒素(NH −N)が硝化菌により硝酸性窒素(NOx−N)へと硝化される。そして、1サイクル好気時間(toc)が経過すると、曝気攪拌装置2が停止される共に水中プロペラ装置3が駆動され、無酸素運転が開始される。この無酸素運転においては、好気運転時に生成された硝酸性窒素(NOx−N)が脱窒菌により還元されて窒素ガスとなり、大気中へと放出される。すなわち、嫌気性菌による脱窒処理が行われる。
【0033】
このとき、プロペラ30が完全に水没した状態で低速回転することから、水中プロペラ装置3による曝気(空気の巻き込み)は行われず、無終端循環水路11の全域が適正な無酸素状態に保持される。また、混合液6Aが循環流動されることから、活性汚泥6aの沈降が防止されて、汚水6と活性汚泥6aとが均一に混合される。また、プロペラ30が低速回転されるため、汚泥フロックが破砕されず、活性汚泥6aの生物学的浄化能力(具体的には、有機物酸化能力、硝化能力、脱窒能力など)が損なわれない。したがって、上記嫌気処理が効果的に行われ、好気運転による好気処理と相俟って、汚水6が良好に処理される。硝化脱窒処理液60は、流出口13から沈殿池15に排出されて汚泥60bを沈降分離されて、処理水60aとして排水系に放出される。一方、処理水60aから沈降分離された汚泥60bは、沈殿池15から無終端循環水路11に返送される。
【0034】
ところで、近年、汚水処理場の小規模化に伴って1池当たりの反応槽が小型化する傾向にあるが、このような小型の反応槽においては、冒頭で述べた如く、無終端循環水路内に好気領域と無酸素領域とを同一池内に併存して形成しておく方式を採用することが困難であり、かかる方式による汚水処理を効果的に行い得ない。しかし、第1汚水処理システムS1にあっては、無終端循環水路11の全域を好気領域及び無酸素領域とすることから、反応槽1が小型である場合にも、汚水処理を効果的に行うことができる。無酸素運転時間帯で起動する水中プロペラ装置3は、水深50cm以下に水没させて運転するため空気の巻き込みが無く槽1内を容易に無酸素状態に保持できる。また、水中プロペラ装置3は汚泥が沈降しない槽内流速0.25m/sec以上となるように低速回転(20〜500rpm)で運転するため、槽1内の全域にわたり、流入汚水6と汚泥6aが攪拌混合され、前述した効果と相俟って脱窒効果を高めることができる。
【0035】
また、演算結果(11)(12)に基づいて余剰汚泥引抜装置4つまり余剰汚泥引抜ポンプ42が運転され、余剰汚泥61が引き抜かれる。このとき、余剰汚泥61が反応槽1から直接に引き抜かれるから、余剰汚泥を従来システムSにおける如く沈殿池115から引き抜く場合と異なって、引き抜き汚泥の濃度変化が小さく、ASRT制御を適正に行うことができる。また、余剰汚泥61の引き抜きを、好気運転又は無酸素運転とは無関係に行うことができる。すなわち、余剰汚泥引抜ポンプ42の運転を、曝気攪拌装置2及び水中プロペラ装置3の運転とは独立して行うことができ、ASRT制御をより簡便に行うことができる。
【0036】
さらに、上記したASRT制御にあっては、当該システムS1に固有の基本条件(1)〜(5)を設定しておけば、運転条件(6)〜(8)を変更するのみで運転状況に応じた適正なASRT制御を行うことができる。すなわち、ASRT制御に必要なデータの多くがシステムS1,S2,S3に固有の基本条件データ(1)〜(5)であり、運転状況に応じては僅かな運転条件データ(6)〜(8)を入力するのみでよいから、従来システムSのように、作業者に熟練が必要とされず、OD法による汚水処理を常に良好且つ適正に行うことができる。さらに、制御操作をタッチパネル51により行うようにしているから、データ入力や運転状況の確認等を、高度の熟練を必要とすることなく、容易且つ簡便に行うことができる。
【0037】
なお、本発明は上記した実施の形態に限定されず、本発明の基本原理を逸脱しない範囲において、適宜に改良,変更することができる。
【0038】
例えば、図6は第2の実施の形態を示したもので、この実施の形態における本発明に係る汚水処理システム(以下「第2汚水処理システム」という)S2では、無終端循環水路11の前後両端部位に前記した縦軸型の曝気攪拌装置2,2が設けられている。第2汚水処理システムS2は、2台の曝気攪拌装置2,2が設けられている点及び両曝気攪拌装置2,2が同期して発停制御される点を除いて、第1汚水処理システムS1と同一構成をなすものであり、第1汚水処理システムS1と同様に効果的な汚水処理を行うことができる。また、図7は第3の実施の形態を示したもので、この実施の形態における本発明に係る汚水処理システム(以下「第3汚水処理システム」という)S3では、無終端循環水路11を隔壁18a及び整流壁18bを設けた馬蹄形とした点、2台の水中プロペラ装置3,3が設けられている点及び両水中プロペラ装置3,3が同期して発停制御される点を除いて、第2汚水処理システムS2と同一構成をなすものであり、第1及び第2汚水処理システムS1,S2と同様に効果的な汚水処理を行うことができる。反応槽1が小型のものである場合には、第1汚水処理システムS1における如く、一般に1台の曝気攪拌装置2で充分であるが、反応槽1が大型のものである場合や能力の低い曝気攪拌装置2を使用する場合等には、第2又は第3汚水処理システムS2,S3のように、必要に応じて、2台以上の曝気攪拌装置2…又は水中プロペラ装置3…を設けておくことができる。
【0039】
また、運転状況に応じて変更すべきデータが「(6)流入汚水量,(7)最低水温,(8)ディッチ内MLSS濃度」にすぎないから、これらを流量計,温度計,MLSS計により検出して、その検出データを制御器50に入力するように構成しておくことができる。このように構成しておけば、人為的な運転条件データの入力を排除することができ、完全な自動制御も可能となる。但し、流量計,温度計,MLSS計による検出及びその検出データの入力はリアルタイムで行う必要はなく、定期的或いは運転状況の変化が確認されたときにおいて行うようにすればよい。また、タッチパネル51は、システムS1,S2,S3の運転作業を質問方式で表示し且つ操作しうるものとしたり、処理系統や運転状況等を表示するグラフィックパネルと組み合わせたものとしておくことができる。
【0040】
【実施例】
実施例1として、第1汚水処理システムS1を使用して、各装置2,3,4を図4に示すタイムサイクルパターンで運転させた。曝気攪拌装置2としては、流入汚水量800m/日での必要酸素量の200%を確保でき、無終端循環水路11内の混合液6Aを汚泥6aが沈降しない0.25m/sec以上の流速で流動させる能力を有する縦軸型のものを使用した。水中プロペラ装置3としては、曝気攪拌装置2と同様に、無終端循環水路11内の混合液6Aを0.25m/sec以上の流速で流動させ得るものを使用した。余剰汚泥引抜装置4において、余剰汚泥引抜ポンプ42としては下記の性能を有するものを使用し、固液分離機41としては多重円板外胴型スクリュープレス脱水機を使用した。また、基本条件データ(1)〜(5)及び運転条件データ(6)〜(8)並びに出力値(演算値)(9)〜(15)は、次の通りである。
【0041】
(1)ディッチ容量:VA=800(m
(2)計画流入汚水量:Qd=800(m/日)
(3)流入汚水SS濃度:Xi=180(mg/L)
(4)流入SS当たり汚泥発生率:α=0.8
(5)余剰汚泥ポンプ性能:qw=10.0(m/h)
(6)流入汚水量:Qi=400(m/日)
(7)最低水温:T=15(℃)
(8)ディッチ内MLSS濃度:XA=3000(mg/L)
(9)ASRT:ASRT=8.9(日)
(10)SRT:SRT=17.8(日)
(11)日余剰汚泥引抜量:Qwa=22(m/日)
(12)余剰汚泥引抜時間:tq=2.2(h/日)
(13)好気・無酸素繰り返しサイクル数:f=6(回/日)
(14)1サイクル好気時間:toc=0.86(h/サイクル)
(15)1サイクル無酸素時間:tac=3.14(h/サイクル)
【0042】
また、実施例2として、実施例1と同一構成の第1汚水処理システムS1を使用して、各装置2,3,4を図5に示すタイムサイクルパターンで運転させた。基本条件データ(1)〜(5)及び運転条件データ(6)〜(8)並びに出力値(演算値)(9)〜(15)は、次の通りである。
【0043】
(1)ディッチ容量:VA=800(m
(2)計画流入汚水量:Qd=800(m/日)
(3)流入汚水SS濃度:Xi=180(mg/L)
(4)流入SS当たり汚泥発生率:α=0.8
(5)余剰汚泥ポンプ性能:qw=10.0(m/h)
(6)流入汚水量:Qi=800(m/日)
(7)最低水温:T=15(℃)
(8)ディッチ内MLSS濃度:XA=3000(mg/L)
(9)ASRT:ASRT=8.9(日)
(10)SRT:SRT=17.8(日)
(11)日余剰汚泥引抜量:Qwa=44(m/日)
(12)余剰汚泥引抜時間:tq=4.4(h/日)
(13)好気・無酸素繰り返しサイクル数:f=6(回/日)
(14)1サイクル好気時間:toc=1.72(h/サイクル)
(15)1サイクル無酸素時間:tac=2.28(h/サイクル)
【0044】
また、比較例1として、図8に示す従来システムSを使用して、両曝気攪拌装置102,102を図9に示すタイムサイクルパターン(好気・無酸素繰り返しサイクル数:6(回/日),1サイクル好気時間:1(h),1サイクル無酸素時間:3(h))で高低速運転させた。各曝気攪拌装置102は、流入汚水量800m/日での必要酸素量の100%を確保できるものである。両曝気攪拌装置102,102は、好気運転においては60Hzで高速駆動して、無終端循環水路111を好気状態に保持し、無酸素運転においては20Hzで低速駆動して、無終端循環水路111を無酸素状態に保持すると共に混合液106Aを0.25m/sec以上の流速で流動させた。また、上記基本条件データ(1)〜(4)及び運転条件データ(6)〜(8)に対応するディッチ容量等は、ディッチ内MLSS濃度が2800(m/L)である点を除いて、実施例1と同一である。
【0045】
また、比較例2として、比較例1と同一構成の従来システムSを使用して、両曝気攪拌装置102,102を図10に示すタイムサイクルパターン(好気・無酸素繰り返しサイクル数:6(回/日),1サイクル好気時間:2(h),1サイクル無酸素時間:2(h))で高低速運転させた。両曝気攪拌装置102,102は、比較例1と同様に、好気運転においては60Hzで高速駆動して、無終端循環水路111を好気状態に保持し、無酸素運転においては20Hzで低速駆動して、無終端循環水路111を無酸素状態に保持すると共に混合液106Aを0.25m/sec以上の流速で流動させた。また、上記基本条件データ(1)〜(4)及び運転条件データ(6)〜(8)に対応するディッチ容量等は、ディッチ内MLSS濃度が3800(m/L)である点を除いて、実施例2と同一である。
【0046】
そして、各々の場合において、2ヶ月間継続運転した後の流入汚水6,106及び処理水60a,160aのBOD(mg/L)及びT−N(mg/L)を測定して、汚水処理効果を確認した。
【0047】
その結果は表1に示す通りであり、本発明に係る汚水処理システム(第1汚水処理システム)S1を使用した場合は、従来システムSを使用した場合に比して汚水処理が効果的に行われることが確認された。
【0048】
【表1】

Figure 0003771870
【0049】
【発明の効果】
以上の説明から容易に理解されるように、本発明の汚水処理システムによれば、冒頭で述べた問題を生じることなく、OD法による汚水処理を効率よく効果的に行い得て、処理水質を向上させることができる。また、本発明の汚水処理システムによれば、運転状況に変化に容易に対応することができ、未熟練者でも運転状況に応じた適正な処理を行うことができる。
【図面の簡単な説明】
【図1】第1汚水処理システムを示す平面図である。
【図2】図1のII−II線に沿う縦断正面図である。
【図3】第1汚水処理システムにおける制御フローの一例を示すチャート図である。
【図4】第1汚水処理システムを使用した実施例1における曝気攪拌装置、水中プロペラ装置及び余剰汚泥引抜装置の運転パターン図である。
【図5】第1汚水処理システムを使用した実施例2における曝気攪拌装置、水中プロペラ装置及び余剰汚泥引抜装置の運転パターン図である。
【図6】第2汚水処理システムを示す図1相当の平面図である。
【図7】第3汚水処理システムを示す図1相当の平面図である。
【図8】従来システムを示す図1相当の平面図である。
【図9】従来システムを使用した比較例1における曝気攪拌装置の運転パターン図である。
【図10】従来システムを使用した比較例2における曝気攪拌装置の運転パターン図である。
【符号の説明】
1…反応槽、2…曝気攪拌装置、3…水中プロペラ装置、4…余剰汚泥引抜装置、5…制御装置、6…汚水、6a…活性汚泥、6A…混合液、11…無終端循環水路、15…沈殿池、20,21…曝気攪拌翼、30…プロペラ、41…固液分離機、42…余剰汚泥引抜ポンプ、50…制御器、51…タッチパネル、D…深さ、S1,S2,S3…汚水処理システム。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sewage treatment system using an oxidation ditch method.
[0002]
BACKGROUND OF THE INVENTION
The denitrification treatment system using the oxidation ditch (hereinafter abbreviated as “OD”) method includes a zone forming operation system in which an endless circulation channel is divided into an aerobic treatment region and an anoxic treatment region, An intermittent aeration operation system in which the inside of a circulating water channel is changed to an aerobic state and an anoxic state over time by an intermittent operation of an aeration stirrer provided in the circulation channel is well known. However, the former is not practical enough in recent years when the sewage treatment plant tends to become smaller because the channel volume becomes larger than necessary. On the other hand, in the latter case, since the entire endless circulation channel is an aerobic region and an oxygen-free region, it is possible to cope with the downsizing of the sewage treatment plant. Therefore, it is impossible to prevent sludge sedimentation and accumulation in an oxygen-free state, resulting in a reduction in processing efficiency due to uneven mixing of activated sludge and sewage.
[0003]
Therefore, conventionally, as a sewage treatment system that solves this problem, as shown in FIG. 8, a partition wall 110 is arranged in an oval reaction tank (OD tank) 101 to form an endless circulation water channel 111. The endless circulating water channel 111 is provided with vertical aeration agitating devices 102 and 102 capable of controlling the number of revolutions at both ends of the terminal circulating water channel 111, and the both agitating devices 102 and 102 are intermittently operated at high and low speeds. Has been proposed (hereinafter, referred to as “conventional system S”) in which the entire region is held alternately in an aerobic state and an anoxic state. According to the conventional system S, the aeration and agitation devices 102 and 102 are circulated and fluidized while aeration and agitation of the mixed liquid 106A of the influent sewage 106 and the activated sludge, and the nitrification treatment as aerobic treatment is performed. By the low-speed operation of the agitators 102, 102, the mixed solution is circulated and flowed without aeration, and denitrification treatment, which is an oxygen-free treatment, is performed while preventing sludge settling. Nitrogen treatment can be performed. That is, in aerobic operation (high-speed operation), ammonia nitrogen is nitrified by nitrifying bacteria which are aerobic bacteria contained in activated sludge (NH3+ 2O2→ NO3 + H++ H2O) In oxygen-free operation (low-speed operation), nitrate nitrogen is denitrified by denitrifying bacteria, which are facultative anaerobic bacteria mixed with nitrifying bacteria in activated sludge (2NO)3 + 10H → N2+ 4H2O + 2OH). Thus, the mixed liquid (processed mixed liquid) 160 that has been subjected to nitrification and denitrification is discharged from the reaction tank 101 to the sedimentation basin 115 and discharged from the sedimentation basin 115 as treated water (supernatant water) 160a. Further, sludge (return sludge) 160b separated (settling separated) from the treated water 160a in the settling basin 115 is returned to the reaction tank 101, and a part thereof is discharged as excess sludge 161 to the outside of the treatment system. The excess sludge 161 is dehydrated by the dehydrator 141 and processed as a solid content (dehydrated sludge) 161 a, and the liquid component (separated liquid) 161 b separated from the solid content 161 a is returned to the reaction tank 101.
[0004]
However, in the conventional system S, since the aeration stirrers 102 and 102 are rotationally driven even in the absence of oxygen, the mixture (106A) is stirred by the aeration stirrers 102 and 102 so that air (oxygen) ), Even if the intake amount is reduced, some air (oxygen) is taken in, and there is a problem that an appropriate oxygen-free state cannot be ensured and denitrification treatment, which is oxygen-free treatment, cannot be performed effectively. Further, if the aeration and agitation devices 102 and 102 are operated at a low speed to ensure an appropriate oxygen-free state, the mixed solution 106A does not flow sufficiently, and sludge sedimentation in the oxygen-free state cannot be prevented.
[0005]
By the way, SRT (Solids Retention Time) which shows the average residence time in the reaction tank until activated sludge is discharged out of the treatment system as SS in surplus sludge and final sedimentation basin effluent (treated water) is activated sludge. There is a close relationship with the growth of microorganisms, and in order for microorganisms to grow in the reaction tank, there is a relationship of μ> 1 / SRT between the SRT and the specific growth rate μ (1 / day) of the microorganism. is necessary. As described above, SRT is an important index for judging whether activated sludge microorganisms (organic removal bacteria, nitrifying bacteria, etc.), filamentous bacteria and actinomycetes that impede treatment can grow in the tank. . That is, in the activated sludge method, when SRT is set, microbial species that can grow in the treatment system are determined, so it is possible to predict the treated water quality from the SRT, and the activated sludge is configured by controlling the SRT. It is possible to utilize or suppress microorganisms having a specific function among the microorganisms that perform the process. Thus, in the OD method in which nitrification and denitrification for the purpose of biological nitrogen removal is performed, the reaction tank changes between anoxic and aerobic conditions. Although it is necessary to consider the growth of organisms, the growth rate of bacteria involved in organic matter removal is significantly faster than that of nitrifying bacteria. Therefore, if ASRT (Aerobic Solids Retention Time) capable of growing nitrifying bacteria is secured, there is no problem with organic matter. It can be removed. Therefore, in order to control the operation of the sewage treatment system by the OD method, it is necessary to secure an SRT that satisfies the conditions necessary for the growth of nitrifying bacteria, that is, an SRT (ASRT) in an aerobic state.
[0006]
By the way, it is empirically known that the ASRT necessary for achieving complete nitrification can be determined by using the water temperature (average minimum water temperature) T as a parameter. Depending on the processing conditions, the following empirical formula (I) or Calculated from (II).
[0007]
That is, under the condition that the daily fluctuation ratio (maximum hourly sewage quantity / daily average sewage quantity) of the incoming sewage quantity is large (fluctuation ratio of about 2.7),4ASRT required to achieve “-N: 1 mg / L or less”
ASRT ≧ 40.7exp (−0.101 · T) (I)
Obtained under the condition that the daily fluctuation ratio of the influent water amount is relatively small (the fluctuation ratio is about 2.2).4ASRT required to achieve “-N: 1 mg / L or less”
ASRT ≧ 29.7exp (−0.102 · T) (II)
It is obtained by.
[0008]
On the other hand, lengthening the ASRT is an advantageous condition for the growth of nitrifying bacteria, but excessive aeration at low load or no load reduces nitrifying bacteria and leads to a decrease in nitrification rate. When the supply speed fluctuates significantly over a long period, it is necessary to extract excess sludge and adjust the aerobic conditions in accordance with the load. Nitrifying bacteria grow at a constant specific growth rate μ regardless of the concentration of nitrogen load supplied, and finally reach an amount commensurate with the supplied load. As the load increases, the amount of bacterial cells increases. Nitrifying bacteriaIsCompletely nitrification is always achieved if the ASRT, which is considered to be uniformly distributed and retained in the activated sludge, is maintained at the level necessary for the growth of nitrifying bacteria according to the water temperature. Can do. When the inflow load is constant, the amount of surplus sludge generated is also constant, and the amount of nitrifying bacteria drawn out of the system by the surplus sludge is only the amount of growth against the inflow load, and a constant amount of nitrifying bacteria is always maintained in the system. However, when the inflow load fluctuates, the amount of excess sludge also changes accordingly, and the amount of nitrifying bacteria increases and decreases, so in order to maintain a constant amount of nitrifying bacteria in the system, It is indispensable to extract the excess sludge in proportion to the inflow load.
[0009]
Therefore, even in the conventional system S, when controlling such an ASRT, the tank sludge concentration that should be managed by determining an appropriate tank sludge amount for the inflow load is calculated, and the calculated sludge is calculated. An appropriate amount of excess sludge 161 is extracted from the sedimentation basin 115 according to the concentration.
[0010]
However, since the surplus sludge concentration is the same as that of the return sludge 160b from the settling basin 115, it is greatly influenced by fluctuations in the amount of inflow sludge and sludge settling speed. As a result, the excess sludge concentration varies greatly, and it is difficult to maintain the ASRT properly. Moreover, the control (ASRT control) also requires a high level of skill, and it is extremely difficult to efficiently and appropriately perform sewage treatment by the OD method.
[0011]
SUMMARY OF THE INVENTION
An object of this invention is to provide the sewage treatment system which can perform the sewage treatment by OD method efficiently and effectively, without producing such a problem.
[0012]
  The present invention was created to achieve the above object, and the invention of claim 1 is directed to an endless circulation channel for circulating mixed water of sewage and activated sludge, and a predetermined amount of mixing in the channel. An agitating and agitating device for circulating and flowing water by constant speed rotation and aeration and stirring; an underwater propeller device for circulating and flowing a predetermined amount of mixed water by a propeller rotating at a constant speed submerged in the mixed water in the water channel; and An aeration stirrer comprising a control device for alternately starting and stopping the surplus sludge extraction device for extracting excess sludge from the endless circulation channel, the aeration stirrer, and the underwater propeller device, and for controlling the start and stop of the surplus sludge extraction device. By repeating the aerobic operation in which the mixed water circulation flow and aeration and stirring are performed alternately and the oxygen-free operation in which only the mixed water circulation flow is performed by the underwater propeller device, endless circulating water is obtained. In the aerobic state and anaerobic state alternately, and in the sewage treatment device configured to periodically operate the excess sludge extraction device for a predetermined time, the underwater propeller device is mixed at the upper end of the propeller. It is positioned so as to be at least 50 cm deep with respect to the water surface, and the control device is provided with a controller that controls the operation of each device and a touch panel that displays data input and calculation results, and is endlessly circulated. Basic condition data including ditch capacity that is the capacity of the channel, planned inflow sewage amount, flowing sewage SS concentration, sludge generation rate per inflow SS and sludge extraction performance of excess sludge extraction device, sewage inflow amount from flow meter, thermometer Operation condition data including the minimum sewage temperature of incoming sewage from the tank and the MLSS concentration in the endless circulation channel from the MLSS meter. From the data, the number of repeated cycles of the time cycle pattern in units of 24 hours in which the aerobic operation and the anaerobic operation are alternately repeated, the aerobic operation time and the anaerobic operation time in one cycle, and the excess sludge extraction amount are obtained. And automatically or manually performing start / stop control of the aeration stirrer, the underwater propeller device, and the excess sludge extraction device based on the calculated value,in frontThe basic configuration of the present invention is that the mixed water in the endless circulation channel is circulated and flowed at an average flow rate of 0.25 m / sec or more at all times.
[0013]
In a preferred embodiment of such a sewage treatment system, an excess sludge extraction device includes an excess sludge extraction pump that extracts excess sludge from an endless circulation channel, and a solid-liquid separator that separates excess sludge extracted by the pump into a solid-liquid separation. And the liquid component separated by the solid-liquid separator is returned to the endless circulation channel. As the solid-liquid separator, it is preferable to use a multi-disc outer cylinder type screw press dehydrator.
[0014]
The control device controls the start and stop of the aeration stirrer, the underwater propeller device, and the excess sludge extraction device so as to maintain the sludge residence time in the aerobic state set based on the minimum temperature of the influent sewage. Specifically, from the basic condition data specific to the system and the operating condition data determined according to the operating conditions of the system, the operating time and operating cycle of the aerobic operation and the oxygen-free operation and the excess sludge extraction The amount is calculated, and the aeration and agitation device, the underwater propeller device, and the excess sludge extraction device are controlled to start and stop based on the calculated value. Here, the basic condition data includes the ditch capacity (VA (m3)), Planned inflow sewage volume (Qd (m3/ Day)), inflow sludge SS concentration (Xi (mg / L)), sludge generation rate per inflow SS (α), and sludge extraction performance of excess sludge extraction device (excess sludge extraction pump) (qw (m3/ Hour)), and the operating condition data is the amount of inflow sewage (Qi (m3/ Day)), the minimum water temperature (T (° C.)) of the influent sewage and the MLSS concentration in the endless circulation channel (MLSS concentration in the ditch (XA (mg / L)). The start / stop control of the stirring device and the underwater propeller device and the start / stop control of the surplus sludge extraction device can be performed independently without being related to each other. It is preferable to have a touch panel.
[0015]
In addition, the underwater propeller device is preferably disposed so that the propeller is positioned at a depth of at least 50 cm with respect to the water surface of the mixed liquid in the endless circulation channel. Further, the underwater propeller device may rotate the propeller at a low speed so that the mixed solution is not aerated and the sludge in the mixed solution is circulated and flowed at a flow rate that does not cause sedimentation during the stop period of the aeration and stirring device. preferable. Specifically, it is preferable that the underwater propeller device circulates and flows the liquid mixture at a flow rate of 0.25 m / sec or more by rotating the propeller at 20 to 500 rpm.
[0016]
The aeration stirrer is of a vertical axis having an aeration stirrer that rotates around a vertical line, and the submersible propeller device is a straight portion of the endless circulation channel downstream of the aeration stirrer blade. It is preferable that it is located in the side part. In addition, an endless circulation channel is usually provided with one aeration stirrer and one underwater propeller device, but depending on the system configuration conditions such as a large ditch (endless circulation channel) with a large amount of treated water. It is also possible to provide a plurality of aeration stirrers and / or underwater propeller devices.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show a first embodiment of the present invention. A sewage treatment system (hereinafter referred to as “first sewage treatment system”) S1 according to the present invention in this embodiment includes a reaction tank (OD). Tank) 1, one aeration stirrer 2 and an underwater propeller device 3 disposed in the reaction tank 1, an excess sludge extraction device 4 for discharging excess sludge from the reaction tank 1, and these devices 2 and 3 , 4 is controlled. In the following description, for the sake of convenience, front and rear refer to the left and right in FIGS. 1, 2, 6, and 7, and left and right refer to the top and bottom in FIGS. 1, 6, and 7.
[0018]
As shown in FIG. 1 and FIG. 2, the reaction tank 1 has an oblong shape whose horizontal plane is long in the front-rear direction, and an endless circulation channel 11 is formed by a partition wall 10 extending in the front-rear direction at the left and right central part. is there. At appropriate locations on the peripheral wall of the reaction tank 1, inlet / outlet ports 12 and 13 that open to the endless circulation channel 11 are provided. A water supply channel 14 led from a sewage supply source (not shown) is connected to the inflow port 12 so that the sewage 6 as the water to be treated is supplied from the inflow port 12 to the endless circulation channel 11. It has become. A drainage channel 16 led to a sedimentation basin (final sedimentation basin) 15 is connected to the outflow port 13, and a treatment mixture 60 treated (nitrification denitrogenation treatment) by the reaction tank 1 in the sedimentation basin 15. It separates into treated water 60a and sludge (activated sludge) 60b. The treated water 60a obtained by settling and separating the sludge 60b in the settling basin 15 is overflowed and discharged from the settling basin 15 to a predetermined drainage system (not shown). On the other hand, the sedimentation sludge (return sludge) 60b is returned from the bottom of the sedimentation basin 15 to the reaction tank 1, that is, the endless circulation channel 11 through the return path 17. The inflow / outflow ports 12 and 13 are provided at arbitrary locations in the endless circulation channel 11 on the condition that the sewage 6 flowing into the endless circulation channel 11 from the inlet 12 does not short-pass to the outlet 13 as it is. I can leave.
[0019]
As shown in FIGS. 1 and 2, the aeration and stirring device 2 is a vertical axis aerator disposed at the front end portion of the endless circulation channel 11, and the aeration and stirring blades 20 and 21 are fixed in the vicinity of the front end of the partition wall 10. By rotating in the direction (arrow direction in FIG. 1), the mixture 6A of the sewage 6 and the activated sludge 6a is circulated and aerated and stirred in the endless circulation channel 11. The aeration stirring blade includes vertical blades 20 attached radially to the lower end of the vertical rotating shaft 22 and horizontal blades 21 attached in an inclined manner between the adjacent vertical blades 20, 20. Is rotated by a drive motor (not shown) with a speed reducer (transmission), the mixed liquid 6A is aspirated while being stirred, pumped up and aerated, and a swirling flow is formed to make the mixed liquid 6A endless. Circulating and flowing in the circulation channel 11. An arc-shaped rectifying wall 18 is provided at the rear end portion of the endless circulation water channel 11 where the aeration and stirring device 2 is not provided.
[0020]
As shown in FIGS. 1 and 2, the underwater propeller device 3 includes a propeller 30 that is disposed in a state where it is submerged in the mixed liquid 6 </ b> A at an appropriate position (for example, a central portion in the front-rear direction) of the straight end portion of the endless circulation channel 11. In order to circulate and flow the mixed liquid 6A without aeration and at a flow rate that does not cause the sludge in the mixed liquid 6A to settle during the stop period (an oxygen-free operation period described later) of the aeration and stirring device 2 Is configured to rotate at a low speed. In this example, the underwater propeller device 3 is configured to circulate and flow the mixed solution 6A at a flow rate of 0.25 m / sec or more by rotating the propeller at 20 to 500 rpm. The vertical position of the propeller 30 is set so that the depth D from the water surface of the mixed solution 6A (the depth from the water surface of the mixed solution 6A to the upper end of the propeller 30) D is 50 cm or more.
[0021]
The excess sludge extraction device 4 includes an excess sludge extraction path 40 connected to the reaction tank 1, a solid-liquid separator 41 through which the excess sludge extraction path 40 is guided, and an excess sludge extraction path interposed in the excess sludge extraction path 40. A pump 42, a separation liquid return path 43 led from the solid-liquid separator 41 to the reaction tank 1, and a dewatered sludge discharge path 44 led from the solid-liquid separator 41 to a predetermined sludge treatment facility (not shown). The excess sludge 61 is extracted from the reaction tank 1 by the excess sludge extraction pump 42 and is solid-liquid separated in the solid-liquid separator 41, and the dehydrated sludge 61 a as a solid content is discharged from the dehydrated sludge discharge passage 44 to the sludge treatment facility. At the same time, the separated liquid 61b is returned from the separated liquid return path 43 to the reaction tank 1, that is, the endless circulation water path 11. As the excess sludge extraction pump 42, the daily excess sludge extraction amount (Qwa (m3/ Day)), a slurry pump or the like having a necessary and sufficient performance to quantitatively extract the excess sludge 61 can be used. As the solid-liquid separator 41, a dehydrator that can directly and sufficiently dehydrate the low-concentration MLSS (excess sludge 61) in the reaction tank 1 is used. In general, a multi-disc outer cylinder screw press dehydrator is used. Is preferably used. The solid-liquid separator 41 is operated in synchronization with the excess sludge extraction pump 42.
[0022]
As shown in FIG. 1, the control device 5 includes a controller 50 that controls the aeration and stirring device 2, the underwater propeller device 3, and the excess sludge extraction device 4, and a touch panel 51 for performing data input to the controller 50. It comprises. On the touch panel 51, a screen for inputting and displaying each data and calculation result, a screen for setting an operation mode (automatic control operation and manual operation), an operation state (operation time of each device 2, 3, 4) A display screen for displaying the operation elapsed time in real time, an operation screen for performing manual operation, and the like.
[0023]
As shown in FIG. 3, the controller 50 sets the sludge residence time (AS in an aerobic state) set based on the minimum temperature (T (° C.)) of the influent sewage 6.RT(Day)), the aeration and stirring device 2, the underwater propeller device 3 and the excess sludge extraction device 4 are controlled to start and stop, and basic condition data unique to the system S1 and the operating conditions of the system S1. The aerobic / anoxic repetitive cycle (f (times / day)), 1-cycle aerobic time (toc (h / cycle)), 1-cycle anaerobic time (taoc) (H / cycle)) and excess sludge extraction time (tq (h / day)) are calculated, and the devices 2, 3, and 4 are controlled to start and stop based on the calculated values. Here, the basic condition data is a ditch capacity (VA (m3)), Planned inflow sewage volume (Qd (m3/ Day)), influent sewage SS concentration (Xi (mg / L)), sludge generation rate per inflow SS (α), and sludge extraction performance (qw (m) of excess sludge extraction device 4, that is, excess sludge extraction pump 423/ H)), and can be fixedly set according to the configuration, installation location, and the like of the system S1. In addition, the operating condition data includes an inflow sewage amount (Qi (m) that is an inflow amount of the sewage 6 into the endless circulation channel 11.3/ Day)), the minimum water temperature (T (° C.)) of the inflowing sewage 6 and the MLSS concentration (XA (mg / L)) of the mixed liquid 6A in the endless circulating water channel 11, and the operating status of the system S1 (four seasons) Or changes in the surrounding environment of the system installation location, etc.).
[0024]
Thus, according to the controller 50, the following calculation and operation control of the devices 2, 3, and 4 are performed according to the control flow shown in FIG. In this example, the devices 2, 3, and 4 are automatically controlled, and if necessary, the devices can be controlled manually.
[0025]
First, a basic condition data input screen (hereinafter referred to as a “basic condition setting screen”) is displayed on the touch panel 51, and basic condition data (1) to (5) are input.
(1) Ditch capacity: VA (m3)
(2) Planned inflow sewage volume: Qd (m3/Day)
(3) Influent sewage SS concentration: Xi (mg / L)
(4) Sludge generation rate per inflow SS: α
(5) Surplus sludge pump performance: qw (m3/ H)
[0026]
Next, the display screen of the touch panel 51 is changed to display an operation condition data input screen (hereinafter referred to as “operation condition input screen”), and the operation condition data (6) to (8) are input.
(6) Inflow sewage volume: Qi (m3 / day)
(7) Minimum water temperature: T (° C)
(8) MLSS concentration in the ditch: XA (mg / L)
[0027]
When data (1) to (8) are input, calculation by the controller 50 is started, and the following calculation results (9) to (15) are obtained.
(9) ASRT: ASRT (Sun)
(10) SRT: SRT (Sun)
(11) Surplus sludge extraction amount per day: Qwa (m3 / day)
(12) Excess sludge extraction time: tq (h / day)
(13) Aerobic / anoxic cycle number: f (times / day)
(14) 1 cycle aerobic time: toc (h / cycle)
(15) One cycle anoxic time: tac (h / cycle)
[0028]
The contents of the calculation are as follows. As for the ASRT, the empirical formula (I) or (II) described at the beginning is used. In this example, the empirical formula (I) is used. R is the load factor (the ratio of the actual inflow sewage amount qw to the planned inflow sewage amount (maximum inflow sewage amount) Qwa), and the number of aerobic / anoxic cycle cycles (repeated aerobic / anoxic operation per day) The number of times f is determined based on the load factor R. Generally, f is determined in accordance with the magnitude of R in the range of 1 to 6, and the value of f increases as R increases. Further, toT is the total daily aerobic time (h), and taT is the total daily anaerobic time (h).
[0029]
ASRT = 40.7 · exp (−0.101 · T)
SRT = 2 ・ ASRT
Qwd = VA / SRT
R = Qi / Qd
Qwa = Qwa
tq = Qwa / qw
toT = 24 · ASRT · Qi · Xi · α / (XA · VA)
taT = 24-toT
toc = toT / f
tac = taT / f
[0030]
Thus, when the calculation results (9) to (15) are obtained by the above calculation, these are displayed on the operation condition setting screen of the touch panel 51. On this operating condition condition setting screen, input values of the operating condition data (6) to (8) are also displayed. After confirming these display values (6) to (15), the operator selects whether or not to perform automatic control on the operation mode setting screen of the touch panel 51. When the automatic control operation OFF is selected, each of the devices 2, 3, and 4 can be operated by manual operation. When the automatic control operation ON is selected, each of the devices 2, 3, and 4 is calculated by the controller 50 (9 ) To (15), the automatic control operation is performed as follows. In the manual operation, the operator operates the devices 2, 3, and 4 based on the calculation results (9) to (15). Further, when it is necessary to change or correct the display value (particularly, the input value of the operation condition data (6) to (8)) on the operation condition setting screen, the correction value is input as shown in FIG. Further, when it is necessary to change the operation mode or the operation conditions (6) to (8) after the automatic operation or the manual operation is started, the change is performed by the touch panel 51.
[0031]
In the automatic control operation, the aeration stirrer 2 and the underwater propeller device 3 alternate with a time cycle pattern (for example, the time cycle pattern shown in FIG. 4 or FIG. 5) determined by the calculation results (13) to (15). It is controlled on and off.
[0032]
Thus, in the aerobic operation in which the aeration and stirring device 2 is driven, the mixed liquid 6A of the sewage 6 and the activated sludge 6a is circulated and flown in the endless circulation channel 11 and aeration and agitation are performed. The entire area of the terminal circulation channel 11 is maintained in an aerobic state, and organic substances in the sewage 6 are decomposed by aerobic bacteria and ammonia nitrogen (NH) contained in the sewage 64 +-N) is nitrate nitrogen (NOx) by nitrifying bacteria-N) to be nitrified. When one cycle aerobic time (toc) elapses, the aeration and stirring device 2 is stopped, the underwater propeller device 3 is driven, and the oxygen-free operation is started. In this oxygen-free operation, nitrate nitrogen (NOx) generated during aerobic operation-N) is reduced by denitrifying bacteria into nitrogen gas and released into the atmosphere. That is, the denitrification process by anaerobic bacteria is performed.
[0033]
At this time, since the propeller 30 rotates at a low speed in a completely submerged state, aeration (intake of air) by the underwater propeller device 3 is not performed, and the entire region of the endless circulation water channel 11 is maintained in an appropriate oxygen-free state. . Further, since the mixed liquid 6A is circulated and flowed, the settling of the activated sludge 6a is prevented, and the sewage 6 and the activated sludge 6a are uniformly mixed. Further, since the propeller 30 is rotated at a low speed, the sludge floc is not crushed, and the biological purification ability (specifically, the organic matter oxidation ability, nitrification ability, denitrification ability, etc.) of the activated sludge 6a is not impaired. Therefore, the anaerobic treatment is effectively performed, and the sewage 6 is treated well in combination with the aerobic treatment by the aerobic operation. The nitrification / denitrification treatment liquid 60 is discharged from the outlet 13 to the settling basin 15, where the sludge 60b is settled and separated, and discharged into the drainage system as treated water 60a. On the other hand, the sludge 60b settled and separated from the treated water 60a is returned to the endless circulation channel 11 from the settling basin 15.
[0034]
By the way, in recent years, the reaction tank per pond tends to be miniaturized with the downsizing of the sewage treatment plant. In such a small reaction tank, as described at the beginning, in the endless circulating water channel, In addition, it is difficult to adopt a method in which an aerobic region and an oxygen-free region are formed in the same pond, and sewage treatment by this method cannot be performed effectively. However, in the first sewage treatment system S1, since the entire region of the endless circulation channel 11 is an aerobic region and an anoxic region, the sewage treatment can be effectively performed even when the reaction tank 1 is small. It can be carried out. The underwater propeller device 3 activated in the anoxic operation time zone is operated by being submerged at a water depth of 50 cm or less, so that there is no air entrainment and the tank 1 can be easily maintained in an anoxic state. Moreover, since the underwater propeller device 3 is operated at a low speed rotation (20 to 500 rpm) so that the in-tank flow velocity is 0.25 m / sec or more at which the sludge does not settle, the inflow sewage 6 and the sludge 6a are spread over the entire area in the tub 1. By mixing with stirring, the denitrification effect can be enhanced in combination with the effects described above.
[0035]
Further, the excess sludge extraction device 4, that is, the excess sludge extraction pump 42 is operated based on the calculation results (11) and (12), and the excess sludge 61 is extracted. At this time, since the excess sludge 61 is directly extracted from the reaction tank 1, unlike the case where the excess sludge is extracted from the sedimentation basin 115 as in the conventional system S, the concentration change of the extracted sludge is small and the ASRT control is appropriately performed. Can do. Further, the excess sludge 61 can be extracted regardless of the aerobic operation or the oxygen-free operation. That is, the operation of the excess sludge extraction pump 42 can be performed independently of the operations of the aeration stirring device 2 and the underwater propeller device 3, and the ASRT control can be performed more easily.
[0036]
Further, in the above-described ASRT control, if the basic conditions (1) to (5) specific to the system S1 are set, the operating conditions can be changed only by changing the operating conditions (6) to (8). Accordingly, appropriate ASRT control can be performed. That is, most of the data necessary for ASRT control is basic condition data (1) to (5) unique to the systems S1, S2, and S3, and a small amount of operating condition data (6) to (8) depending on the driving situation. ), It is only necessary to input the sewage treatment by the OD method without requiring skill as in the case of the conventional system S. Furthermore, since the control operation is performed by the touch panel 51, data input, operation status confirmation, and the like can be easily and easily performed without requiring a high degree of skill.
[0037]
It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately improved and changed without departing from the basic principle of the present invention.
[0038]
For example, FIG. 6 shows the second embodiment, and in the sewage treatment system (hereinafter referred to as “second sewage treatment system”) S2 according to the present embodiment in this embodiment, before and after the endless circulation water channel 11 The vertical axis aeration and stirring devices 2 and 2 are provided at both end portions. The second sewage treatment system S2 is the first sewage treatment system, except that two aeration agitators 2 and 2 are provided and the aeration agitators 2 and 2 are controlled on and off in synchronization. It has the same configuration as S1 and can perform effective sewage treatment in the same manner as the first sewage treatment system S1. FIG. 7 shows a third embodiment. In the sewage treatment system (hereinafter referred to as “third sewage treatment system”) S3 according to the present invention in this embodiment, the endless circulation water channel 11 is formed as a partition wall. Except for a horseshoe shape provided with 18a and a rectifying wall 18b, two underwater propeller devices 3 and 3, and both underwater propeller devices 3 and 3 being synchronized and controlled. It has the same configuration as the second sewage treatment system S2, and an effective sewage treatment can be performed in the same manner as the first and second sewage treatment systems S1 and S2. When the reaction tank 1 is small, one aeration and stirring device 2 is generally sufficient as in the first sewage treatment system S1, but when the reaction tank 1 is large or the capacity is low. When using the aeration stirrer 2, etc., as in the second or third sewage treatment system S2, S3, two or more aeration stirrers 2 or an underwater propeller device 3 are provided as necessary. I can leave.
[0039]
In addition, since the data to be changed according to the operating situation is only “(6) Inflow sewage amount, (7) Minimum water temperature, (8) MLSS concentration in the ditch”, these are measured by a flow meter, thermometer, and MLSS meter. It can be configured to detect and input the detection data to the controller 50. With this configuration, it is possible to eliminate the input of artificial operating condition data, and complete automatic control is possible. However, the detection by the flow meter, the thermometer, and the MLSS meter and the input of the detection data do not need to be performed in real time, and may be performed periodically or when a change in the operation state is confirmed. The touch panel 51 can display and operate the operation operations of the systems S1, S2, and S3 in a question system, or can be combined with a graphic panel that displays a processing system, an operation state, and the like.
[0040]
【Example】
As Example 1, each apparatus 2, 3, and 4 was operated by the time cycle pattern shown in FIG. 4 using 1st sewage treatment system S1. As aeration and stirring device 2, the amount of inflow sewage is 800m.3A vertical axis type that can secure 200% of the required oxygen amount per day and has the ability to flow the mixed liquid 6A in the endless circulation channel 11 at a flow rate of 0.25 m / sec or more at which the sludge 6a does not settle. used. As the underwater propeller device 3, a device capable of flowing the mixed solution 6 </ b> A in the endless circulating water channel 11 at a flow rate of 0.25 m / sec or more was used, as in the aeration stirring device 2. In the surplus sludge extraction apparatus 4, a surplus sludge extraction pump 42 having the following performance was used, and a multi-disc outer cylinder screw press dehydrator was used as the solid-liquid separator 41. The basic condition data (1) to (5), the operation condition data (6) to (8), and the output values (calculated values) (9) to (15) are as follows.
[0041]
(1) Ditch capacity: VA = 800 (m3)
(2) Planned inflow sewage amount: Qd = 800 (m3/Day)
(3) Inflow sewage SS concentration: Xi = 180 (mg / L)
(4) Sludge generation rate per inflow SS: α = 0.8
(5) Surplus sludge pump performance: qw = 10.0 (m3/ H)
(6) Inflow sewage amount: Qi = 400 (m3/Day)
(7) Minimum water temperature: T = 15 (° C.)
(8) MLSS concentration in the ditch: XA = 3000 (mg / L)
(9) ASRT: ASRT = 8.9 (Sun)
(10) SRT: SRT = 17.8 (Sun)
(11) Surplus sludge extraction amount per day: Qwa = 22 (m3/Day)
(12) Excess sludge extraction time: tq = 2.2 (h / day)
(13) Aerobic / anoxic cycle number: f = 6 (times / day)
(14) 1 cycle aerobic time: toc = 0.86 (h / cycle)
(15) One cycle oxygen-free time: tac = 3.14 (h / cycle)
[0042]
Moreover, as Example 2, each apparatus 2, 3, and 4 was operated by the time cycle pattern shown in FIG. 5 using 1st sewage treatment system S1 of the same structure as Example 1. FIG. The basic condition data (1) to (5), the operation condition data (6) to (8), and the output values (calculated values) (9) to (15) are as follows.
[0043]
(1) Ditch capacity: VA = 800 (m3)
(2) Planned inflow sewage amount: Qd = 800 (m3/Day)
(3) Inflow sewage SS concentration: Xi = 180 (mg / L)
(4) Sludge generation rate per inflow SS: α = 0.8
(5) Surplus sludge pump performance: qw = 10.0 (m3/ H)
(6) Inflow sewage amount: Qi = 800 (m3/Day)
(7) Minimum water temperature: T = 15 (° C.)
(8) MLSS concentration in the ditch: XA = 3000 (mg / L)
(9) ASRT: ASRT = 8.9 (Sun)
(10) SRT: SRT = 17.8 (Sun)
(11) Surplus sludge extraction amount per day: Qwa = 44 (m3/Day)
(12) Excess sludge extraction time: tq = 4.4 (h / day)
(13) Aerobic / anoxic cycle number: f = 6 (times / day)
(14) 1 cycle aerobic time: toc = 1.72 (h / cycle)
(15) One cycle oxygen-free time: tac = 2.28 (h / cycle)
[0044]
Further, as Comparative Example 1, using the conventional system S shown in FIG. 8, both aeration and agitation devices 102 and 102 are time cycle patterns shown in FIG. 9 (aerobic / anoxic repetitive cycle number: 6 (times / day). 1 cycle aerobic time: 1 (h), 1 cycle anoxic time: 3 (h)). Each aeration stirrer 102 has an inflow sewage amount of 800 m.3/ 100% of the required amount of oxygen per day can be secured. Both aeration stirrers 102 and 102 are driven at a high speed at 60 Hz in an aerobic operation to keep the endless circulation channel 111 in an aerobic state, and are driven at a low speed at 20 Hz in an anaerobic operation to endless circulation channel While maintaining 111 in an oxygen-free state, the mixed solution 106A was caused to flow at a flow rate of 0.25 m / sec or more. Further, the ditch capacity corresponding to the basic condition data (1) to (4) and the operation condition data (6) to (8) has an MLSS concentration in the ditch of 2800 (m3/ L) is the same as the first embodiment except for the point.
[0045]
Further, as Comparative Example 2, using the conventional system S having the same configuration as that of Comparative Example 1, both aeration and agitation devices 102 and 102 are arranged in a time cycle pattern (aerobic / anoxic repetitive cycle number: 6 (times / Day), 1 cycle aerobic time: 2 (h), 1 cycle anoxic time: 2 (h)). Both aeration stirrers 102 and 102 are driven at a high speed at 60 Hz in an aerobic operation, hold the endless circulation water channel 111 in an aerobic state, and are driven at a low speed at 20 Hz in an anaerobic operation, as in Comparative Example 1. Then, the endless circulation channel 111 was maintained in an oxygen-free state, and the mixed solution 106A was caused to flow at a flow rate of 0.25 m / sec or more. The ditch capacity corresponding to the basic condition data (1) to (4) and the operating condition data (6) to (8) has a MLSS concentration in the ditch of 3800 (m3/ L) is the same as the second embodiment except for the point.
[0046]
And in each case,After 2 months of continuous operationInflow sewage 6,106 andPlaceThe BOD (mg / L) and TN (mg / L) of the physical waters 60a and 160a were measured to confirm the sewage treatment effect.
[0047]
The results are as shown in Table 1. When the sewage treatment system (first sewage treatment system) S1 according to the present invention is used, the sewage treatment is performed more effectively than when the conventional system S is used. It was confirmed that
[0048]
[Table 1]
Figure 0003771870
[0049]
【The invention's effect】
As can be easily understood from the above description, according to the sewage treatment system of the present invention, wastewater treatment by the OD method can be efficiently and effectively performed without causing the problems described at the beginning, and the quality of the treated water can be improved. Can be improved. Moreover, according to the sewage treatment system of the present invention, it is possible to easily cope with changes in the driving situation, and even an unskilled person can perform an appropriate treatment according to the driving situation.
[Brief description of the drawings]
FIG. 1 is a plan view showing a first wastewater treatment system.
FIG. 2 is a longitudinal front view taken along the line II-II in FIG.
FIG. 3 is a chart showing an example of a control flow in the first sewage treatment system.
FIG. 4 is an operation pattern diagram of the aeration and agitation device, the underwater propeller device, and the excess sludge extraction device in Example 1 using the first sewage treatment system.
FIG. 5 is an operation pattern diagram of an aeration stirrer, an underwater propeller device, and an excess sludge extraction device in Example 2 using the first sewage treatment system.
FIG. 6 is a plan view corresponding to FIG. 1 and showing a second sewage treatment system.
FIG. 7 is a plan view corresponding to FIG. 1 and showing a third sewage treatment system.
FIG. 8 is a plan view corresponding to FIG. 1 showing a conventional system.
FIG. 9 is an operation pattern diagram of the aeration and agitation apparatus in Comparative Example 1 using a conventional system.
FIG. 10 is an operation pattern diagram of the aeration and agitation apparatus in Comparative Example 2 using a conventional system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Reaction tank, 2 ... Aeration stirring apparatus, 3 ... Underwater propeller apparatus, 4 ... Excess sludge extraction apparatus, 5 ... Control apparatus, 6 ... Sewage, 6a ... Activated sludge, 6A ... Mixed liquid, 11 ... Endless circulation channel, DESCRIPTION OF SYMBOLS 15 ... Sedimentation basin, 20, 21 ... Aeration stirring blade, 30 ... Propeller, 41 ... Solid-liquid separator, 42 ... Excess sludge extraction pump, 50 ... Controller, 51 ... Touch panel, D ... Depth, S1, S2, S3 ... Sewage treatment system.

Claims (4)

汚水と活性汚泥との混合水を循環させる無終端循環水路と、当該水路内の所定量の混合水を定速回転により循環流動させると共に曝気攪拌させる曝気攪拌装置と、前記水路内の混合水中に水没させた定速回転をするプロペラにより所定量の混合水を循環流動させる水中プロペラ装置と、前記無終端循環水路内から余剰汚泥を引き抜く余剰汚泥引抜装置と、曝気攪拌装置と水中プロペラ装置とを交互に発停制御すると共に余剰汚泥引抜装置を発停制御する制御装置とを具備し、曝気攪拌装置により混合水の循環流動と曝気攪拌が行われる好気運転と、水中プロペラ装置により混合水の循環流動のみが行われる無酸素運転とを交互に繰り返すことにより、無終端循環水路の全域を好気状態と無酸素状態とに交互に保持すると共に、余剰汚泥引抜装置を定期的に所定時間運転する構成とした汚水処理装置において、前記水中プロペラ装置を、そのプロペラの上端が混合水の水面に対して少なくとも50cmの深さとなるように位置させ、また前記制御装置を、前記各装置の運転を制御する制御器とデータ入力や演算結果を表示するタッチパネルとを備え、無終端循環水路の容量であるディッチ容量、計画流入汚水量、流水汚水SS濃度、流入SS当り汚泥発生率及び余剰汚泥引抜装置の汚泥引抜性能を含む基本条件データと、流量計からの汚水流入量、温度計からの流入汚水の最低水温及びMLSS計からの無終端循環水路内のMLSS濃度を含む運転条件データとが入力され、当該基本条件データ及び運転条件データから、前記好気運転と無酸素運転を交互に繰り返す24時間を単位とするタイムサイクルパターンの繰り返しサイクル数と、1サイクル中の好気運転時間及び無酸素運転時間と余剰汚泥引抜量とを演算し、当該演算値に基づいて前記曝気攪拌装置と水中プロペラ装置と余剰汚泥引抜装置の発停制御を自動又は手動により行うと共に、前記無終端循環水路内の混合水を常時0.25m/sec以上の平均流動速度で循環流動させるようにしたことを特徴とするオキシデーションディッチ法による汚水処理装置。An endless circulation channel that circulates mixed water of sewage and activated sludge, an aeration stirrer that circulates and flows a predetermined amount of mixed water in the channel by constant speed rotation and aeration and stirring, and mixed water in the channel An underwater propeller device that circulates and flows a predetermined amount of mixed water with a submerged propeller that rotates at a constant speed, an excess sludge extraction device that extracts excess sludge from the endless circulation channel, an aeration stirrer, and an underwater propeller device. An aerobic operation in which the circulating flow and aeration stirring is performed by the aeration stirrer, and the mixed water by the underwater propeller device. By alternately repeating an anaerobic operation in which only the circulation flow is performed, the entire endless circulation channel is held alternately in an aerobic state and an anaerobic state, and excess sludge is withdrawn. In the sewage treatment apparatus configured to operate periodically for a predetermined time, the underwater propeller apparatus is positioned such that the upper end of the propeller is at least 50 cm deep with respect to the water surface of the mixed water, and the control apparatus is , Equipped with a controller for controlling the operation of each device and a touch panel for displaying data input and calculation results, the capacity of the endless circulation channel, the ditch capacity, the planned inflow sewage amount, the flowing sewage SS concentration, the sludge per inflow SS Basic condition data including the rate of occurrence and sludge extraction performance of the excess sludge extraction device, including the amount of sewage inflow from the flow meter, the minimum water temperature of inflow sewage from the thermometer, and the MLSS concentration in the endless circulation channel from the MLSS meter The operation condition data is input, and 24 hours in which the aerobic operation and the anaerobic operation are alternately repeated from the basic condition data and the operation condition data. The aerobic operation time and anoxic operation time in one cycle and the excess sludge extraction amount are calculated, and the aeration stirrer, the underwater propeller device, and the excess sludge are calculated based on the calculated values. the start-stop control of the withdrawing apparatus performs automatically or manually, oxy retardation, characterized in that the mixing water before Symbol endless circulation canals so as to circulate fluid at all times 0.25 m / sec or more average flow velocity Sewage treatment equipment by the ditch method. 余剰汚泥引抜装置が、無終端循環水路から余剰汚泥を引き抜く余剰汚泥引抜ポンプと、当該ポンプにより引き抜いた余剰汚泥を固液分離する固液分離機とを具備し、固液分離機により分離された液分を当該無終循環水路に返送するものである請求項1に記載のオキシデーションディッチ法による汚水処理装置。  The surplus sludge extraction device comprises a surplus sludge extraction pump that extracts excess sludge from the endless circulation channel, and a solid-liquid separator that separates excess sludge extracted by the pump into a solid-liquid separator, and was separated by the solid-liquid separator. The sewage treatment apparatus according to the oxidation ditch method according to claim 1, wherein the liquid is returned to the endless circulation channel. 制御装置が、流入汚水の最低温度に基づいて設定される好気状態における汚泥滞留時間を維持するように、曝気攪拌装置、水中プロペラ装置及び余剰汚泥引抜装置を発停制御するものである請求項1に記載のオキシデーションディッチ法による汚水処理装置。  The control device controls the start and stop of the aeration stirrer, the underwater propeller device, and the excess sludge extraction device so as to maintain the sludge residence time in the aerobic state set based on the minimum temperature of the influent sewage. The sewage treatment apparatus by the oxidation ditch method according to 1. 制御装置が、曝気攪拌装置及び水中プロペラ装置の発停制御と、余剰汚泥引抜装置の発停制御とを相互に関連することなく独立して行うものである請求項1又は請求項3に記載のオキシデーションディッチ法による汚水処理装置。Control device, a start-stop control of aeration stirrer and water propeller device of claim 1 or claim 3 in which independently performed without inter-related and start-stop control of the excess sludge extracting device Sewage treatment equipment using the oxidation ditch method.
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JP4837267B2 (en) * 2004-08-02 2011-12-14 住友重機械エンバイロメント株式会社 Oxidation ditch operation control method and oxidation ditch operation control apparatus
JP4683913B2 (en) * 2004-12-21 2011-05-18 清水建設株式会社 Contaminated soil purification method and apparatus
JP2006289277A (en) * 2005-04-12 2006-10-26 Tsukishima Kikai Co Ltd Nitrate forming nitrification/denitrification method, method for nitrifying/denitrifying ammonia nitrogen-containing liquid and nitrate forming nitrification/denitrification equipment
JP4968876B2 (en) * 2005-09-28 2012-07-04 月島機械株式会社 Treatment method and treatment equipment for treated water
CN102010062B (en) * 2010-12-28 2012-05-23 北京碧水源科技股份有限公司 Double-ring-groove MBR wastewater treatment system
JP2013022470A (en) * 2011-07-14 2013-02-04 Sumitomo Heavy Industries Environment Co Ltd Batch type sewage treatment system and batch type sewage treatment method
JP6024232B2 (en) * 2012-06-20 2016-11-09 株式会社明電舎 Activated sludge concentration control method
WO2015019988A1 (en) 2013-08-05 2015-02-12 シャープ株式会社 Agitating blade, agitating device, beverage manufacturing device and agitating part
SE538527C2 (en) 2014-06-17 2016-09-06 Xylem Ip Man Sarl Plant for the treatment of liquid and method for controlling such a plant
JP6829585B2 (en) * 2016-11-14 2021-02-10 株式会社日水コン Sewage treatment system and sewage treatment method
CN112479374A (en) * 2020-11-11 2021-03-12 绍兴水处理发展有限公司 Internal circulation aerobic biochemical reaction process

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