JP3983825B2 - Control device for oxidation ditch water treatment system - Google Patents

Description

【００２８】
ここに、
r_XS、r_XA、r_XI：生成速度 ［ｍｇ／Ｌ・ｈ］
Y₁、Y₂：収率
K_S ：半飽和定数 ［ｍｇ／Ｌ］
K_fS：半飽和定数
XT：ＭＬＳＳ（活性汚泥微生物）濃度 ［ｍｇ／Ｌ］
XS：ＭＬＳＳの蓄積部分濃度 ［ｍｇ／Ｌ］
XA：ＭＬＳＳの活性部分濃度 ［ｍｇ／Ｌ］
XI：ＭＬＳＳの不活性部分濃度 ［ｍｇ／Ｌ］
fs：XS／XT
fs^M：fsの最大値
S ：有機物濃度 ［ ｍｇ／Ｌ］
R_T ：移動係数 ［ｈ^-1］
R_XA：最大比増殖速度 ［ｈ^-1］
R_XI：最大比死亡速度 ［ｈ^-1］
である。ただし、Ｌはリットルを表わす。
【００２９】
また、硝化反応の動力学モデルを式２で表す。これも、上記文献に記載されているステンストロム（Ｓｔｅｎｓｔｒｏｍ）のモデルに基づいて構成したものである。
【００３０】
【数２】

【００３１】
ここに、
r_XNS、r_XNB：生成速度 ［ｍｇ／Ｌ・ｈ］
r_SNO3、r_SNO2、r_SNH4：硝化反応による基質生成速度 ［ｍｇ／Ｌ・ｈ］
XNS：ニトロソモナス（Ｎｉｔｒｏｓｏｍｏｎａｓ）の濃度［ｍｇ／Ｌ］
XNB：ニトロバクタ（Ｎｉｔｒｏｂａｃｔｅｒ）の濃度 ［ｍｇ／Ｌ］
DO：溶存酸素濃度 ［ｍｇ／Ｌ］
μ_NS(DO)、μ_NB(DO)：モノ（Ｍｏｎｏｄ）による比増殖速度関数［ｈ^-1］
μ_NS ^M、μ_NB ^M：最大比増殖速度 ［ｈ^-1］
D_XNS、D_XNB：比死亡速度 ［ｈ^-1］
r_HNH4：有機物除去反応による基質生成速度 ［ｍｇ／Ｌ・ｈ］
K_DO：半飽和定数 ［ｍｇ／Ｌ］
である。
【００３２】
また、脱窒反応の動力学モデルを式３で表す。これは、「水処理工学」（技報堂出版、１９７６）および文献（「Ｂｉｏｌｏｇｉｃａｌ Ｄｅｎｉｔｒｉｆｉｃａｔｉｏｎ」（Ｄｅｐ． ｏｆ Ｓａｎｉｔａｒｙ ＥｎｇｉｎｅｅｒｉｎｇＴｅｃｈｎｉｃａｌ Ｕｎｉｖ． ｏｆ Ｄｅｎｍａｒｋ、１９７２））に記載のデータより作成したものである。
【００３３】
r_DNO3= -(R_HN+R_SN)XA
r_DNH4= (0.25R_SN+0.02R_HNY₃)XA
r_DXS= -2.21R_HNXA
r_DXA=(R_HNY₃-2.0R_SN)XA ・・・・（３）
【００３４】
ここに、
r_DNO3、r_DNH4、r_DXS、r_DXA：脱窒反応による生成速度 ［ｍｇ／Ｌ・ｈ］
R_HN：生合成型脱窒速度定数 ［ｈ^-1］
R_SN：内生型脱窒速度定数 ［ｈ^-1］
Y₃：収率
である。
【００３５】
また、溶存酸素濃度の収支は式４で表す。
【００３６】
【数３】

【００３７】
ここに、
r_HDO：有機物除去による酸素消費速度 ［ｍｇ／Ｌ・ｈ］
r_NDO：硝化による酸素消費速度 ［ｍｇ／Ｌ・ｈ］
r_DO ：酸素移動速度 ［ｍｇ／Ｌ・ｈ］
Y_NS、Y_NB：収率
K_La ：総括酸素移動容量係数 ［ｈ^-1］
DO_s ：飽和溶存酸素濃度 ［ｍｇ／Ｌ］
である。
【００３８】
また、動力学パラメータは表１のように設定した。
【００３９】
【表１】

【００４０】
また、ディッチ内混合は、図１に示すような循環流を考慮した流下方向の槽列モデルで近似し、各槽間の物質収支をとった。
【００４１】
また、装置条件は「オキシデーションディッチ法に用いる機械式ばっ気装置の開発（建設省技術評価書第８２４０２号）」を参考にして表２のように設定した。
【００４２】
【表２】

【００４３】
また、曝気ロータの特性は、式５のように設定した。
【００４４】
【数４】

【００４５】
ここに、
OC ：ロータ１［ｍ］あたりの酸素供給速度 ［ｋｇ−Ｏ₂／ｍ・ｈ］
NN ：酸素供給効率（軸動力） ［ｋｇ−Ｏ₂／ｋＷｈ］
K_La：総括酸素移動容量係数 ［ｈ^-1］
q ：消費動力 ［ｋＷ］
V_m ：池内平均流速 ［ｍ／ｓ］
L ：水路長 ［ｍ］
φ ：推進力に用いられる投入動力の割合
P_r ：動力投入密度 ［Ｗ／ｍ³］
V_u ：ロータ周速度 ［ｍ／ｓ］
ζ ：水路損失係数
【００４６】
図２、図３、図４は、ＭＬＳＳ濃度を３０００［ｍｇ／Ｌ］と設定して、各々曝気ロータ浸漬深さを１５［ｃｍ］、２０［ｃｍ］、２４［ｃｍ］と変化させ、各図の（ａ）（ｂ）（ｃ）において、各々曝気ロータ回転数を４８［ｒｐｍ］、６０［ｒｐｍ］、７１［ｒｐｍ］と変化させて上記シミュレーションを行ったときのディッチ内溶存酸素濃度分布と処理水中全窒素濃度との関係を示す図である。横軸はディッチを流下方向に６等分した地点を示し、図１に示すように、曝気ロータ設置地点（下水流入地点）Ａから順にＢ、Ｃ、Ｄ、Ｅ、Ｆ（処理水流出地点）と名前をつけている。縦軸は溶存酸素濃度を示す。グラフ内右肩の数字はＦ点での全窒素濃度を示し、かっこ内左側はアンモニア性窒素濃度、右側は硝酸性窒素濃度を示す。
【００４７】
同様に、図５、図６、図７はＭＬＳＳ濃度を４０００［ｍｇ／Ｌ］と設定してシミュレーションを行ったときの結果を示す図であり、図８、図９、図１０はＭＬＳＳ濃度を５０００［ｍｇ／Ｌ］と設定してシミュレーションを行ったときのディッチ内溶存酸素濃度分布と処理水中全窒素濃度との関係を示す図である。
【００４８】
これらの図より、処理水中の全窒素濃度が低いとき、硝酸性窒素分とアンモニア性窒素分とは同程度残存していることがわかる。理解を助けるために、横軸にＦ点での硝酸性窒素濃度とアンモニア性窒素濃度との差を、縦軸に両者の和、すなわち全窒素濃度をとった図を図１１に示す。ＭＬＳＳ濃度が３０００［ｍｇ／Ｌ］（実線）、４０００［ｍｇ／Ｌ］（点線）、５０００［ｍｇ／Ｌ］（一点鎖線）いずれのときも、硝酸性窒素濃度とアンモニア性窒素濃度との差が０のとき、全窒素濃度は最小となる。このことより、発明者らは「処理水中の硝酸性窒素濃度とアンモニア性窒素濃度とが同程度残存するようにすれば、処理水中の全窒素濃度を最小に抑制することができる」という第１の法則を見いだした。
【００４９】
また、図１１から、ＭＬＳＳ濃度が高い方が、処理水中の全窒素濃度をより小さくできることもわかる。このことより、発明者らは「さらに窒素を高度に除去するためには、ＭＬＳＳ濃度を高く保つ必要がある」という第２の法則を見いだした。
【００５０】
第１および第２の法則を実際のオキシデーションディッチ水処理プロセスの運用に適用すれば、下水中の窒素の高度処理を達成することが可能となる。発明者らは、さらに、窒素濃度の計測や分析を必要としないより簡便な方法を発見するために、先の図２〜図１０をより注意深く調べた。これらの図によると、ＭＬＳＳ濃度がいずれの場合も、溶存酸素濃度がＣ〜Ｄ点付近で消失するとき、すなわち好気領域と嫌気領域とがほぼ等しく形成され硝化・脱窒がバランスよく起こっているとき、処理水中の全窒素濃度が低いことがわかる。
この好気領域と嫌気領域の境界の最適点は硝化速度と脱窒速度との比に依存するとも言える。理解を助けるために、硝化速度を通常の値の１０倍に設定した場合（表１のμ_NS ^M、μ_NB ^Mを１０倍にする）のシミュレーション結果を図１２、図１３、図１４に、脱窒速度を通常の値の１０倍に設定した場合（表１のR_HN、R_SNを１０倍にする）のシミュレーション結果を図１５、図１６、図１７に示す。図の見方は図２〜図１０と同様である。
【００５１】
図１２、図１３、図１４では、溶存酸素濃度がＢ点付近で消失するとき、処理水中の全窒素濃度が低い。これは、硝化速度が脱窒速度に比べて大きいと、好気領域が短くてもよいため、処理水質に対して最適な好気領域の終端位置がディッチ中央付近から前方（曝気ロータ側）にずれているのである。一方、図１５、図１６、図１７では、溶存酸素濃度がＥ点付近で消失するとき、処理水中の全窒素濃度が低い。これは、脱窒速度が硝化速度に比べて大きいと、嫌気領域が短くてもよいため、処理水質に対して最適な好気領域の終端位置がディッチ中央付近から後方にずれているのである。
【００５２】
このシミュレーションの条件は、あくまでも理解を助けるために実際の現象と無関係に設定したものであり、実際に硝化速度および脱窒速度が文献値から大きく逸脱することはありえない。ただし、水温、ｐＨ、酸化還元電位などは硝化速度および脱窒速度に若干の影響を及ぼし、その影響の度合いは硝化速度と脱窒速度とで異なる。このことより、発明者らは「通常、窒素除去に対して最適な好気領域と嫌気領域との境界はディッチ中央付近である。ただし、その位置は、水温、ｐＨ、酸化還元電位など微生物活性に影響を与える因子の変動に対して影響を受ける」という第３の法則を見いだした。
【００５３】
最後に、ディッチ内の溶存酸素濃度分布に関して、曝気ロータ回転数と浸漬深さが同じでも、ＭＬＳＳ濃度が異なると溶存酸素濃度分布の勾配が異なることが図２〜図１０よりわかる。理解を助けるために、横軸にＡ点での溶存酸素濃度、縦軸にＦ点での全窒素濃度をとった図を図１８に示す。この図より、ＭＬＳＳ濃度が高いほど全窒素濃度が最小となるＡ点での溶存酸素濃度が高いことがわかる。第３の法則を導出する際にも述べたように、処理水中の全窒素濃度が低いとき、ＭＬＳＳ濃度がいずれの場合も溶存酸素濃度はＣ〜Ｄ点付近で消失していた。すなわち、ＭＬＳＳ濃度が高いほど、勾配の急な溶存酸素濃度分布が形成されているのである。このことより、発明者らは「ＭＬＳＳ濃度が高いほど、溶存酸素濃度分布が急勾配となる」という第４の法則を見いだした。
【００５４】
参考例１．
以下、本発明に係る参考例を図について説明する。図１９は参考例１に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図１９において、図４３と同一符号は同一または相当部分を示している。また、１００は沈澱処理水を放流するための配管ｃに取り付けられた硝酸性窒素濃度計、１０１は同じくアンモニア性窒素濃度計である。１０２は、硝酸性窒素濃度とアンモニア性窒素濃度との差と予め定められた濃度差の目標値との偏差に応じて曝気ロータ２の回転数の目標値を出力する調節計であり、信号線１００ａで硝酸性窒素濃度計１００と、信号線１０１ａでアンモニア性窒素濃度計１０１と、信号線１０２ａで駆動装置３と接続されている。１０３は濃度差の目標値を設定するための設定器であり、信号線１０３ａで調節計１０２と接続されている。設定器１０３に設定する目標値は、第１の法則より−１０〜１０［ｍｇ−Ｎ／Ｌ］の範囲、望ましくは０［ｍｇ−Ｎ／Ｌ］近傍とするとより効果的である。なお、［ｍｇ−Ｎ／Ｌ］は窒素Ｎの濃度を表わす単位を示している。
【００５５】
次に、動作について説明する。処理水中の硝酸性窒素濃度は硝酸性窒素濃度計１００で、アンモニア性窒素濃度はアンモニア性窒素濃度計１０１で計測される。それぞれの計測値は信号線１００ａおよび１０１ａを介して調節計１０２に伝えられる。調節計１０２では、硝酸性窒素濃度とアンモニア性窒素濃度との差と予め定められた濃度差の目標値との偏差に応じて曝気ロータ２の回転数の目標値を、例えば式６に従って出力する。
【００５６】
Ｒ_rot＝Ｒ_rot0＋Ｋ_RDN（ＤＮ^*−ＤＮ） ・・・（６）
ここに、
Ｒ_rot ：曝気ロータの回転数の目標値
Ｒ_rot0：定数
Ｋ_RDN ：定数
ＤＮ^* ：（硝酸性窒素濃度−アンモニア性窒素濃度）の目標値
ＤＮ ：硝酸性窒素濃度−アンモニア性窒素濃度
である。
この演算に必要な濃度差の目標値ＤＮ^* は、設定器１０３の出力として信号線１０３ａを介して得られる。調節計１０２の出力Ｒ_rot は信号線１０２ａを介して駆動装置３に伝えられ、曝気ロータ２の回転数が調節される。
【００５７】
これにより、濃度差ＤＮが目標値ＤＮ^* よりも小さければ、曝気ロータ２の回転数が増加し、好気領域を伸長させる。逆に濃度差ＤＮが目標値ＤＮ^* よりも大きければ、曝気ロータ２の回転数が減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても、処理水中の硝酸性窒素濃度とアンモニア性窒素濃度とが同程度残存するように曝気ロータ２の回転数を自動的に調節すれば、好気領域の終端がディッチ中央付近にくるように調節でき、良好な処理水質を安定して保つことができるようになる。
【００５８】
参考例２．
本発明に係る他の参考例を図について説明する。図２０は参考例２に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図２０において、１０４は硝酸性窒素濃度とアンモニア性窒素濃度との差と予め定められた濃度差の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を出力する調節計であり、信号線１００ａで硝酸性窒素濃度計１００と、信号線１０１ａでアンモニア性窒素濃度計１０１と、信号線１０３ａで濃度差の目標値を設定するための設定器１０３と接続されている。参考例１と同様、設定器１０３に設定する目標値は、−１０〜１０［ｍｇ−Ｎ／Ｌ］の範囲、望ましくは０［ｍｇ−Ｎ／Ｌ］近傍とするとより効果的である。１２は曝気ロータ２の浸漬深さの目標値から越流せき４の高さの目標値を演算する演算器であり、調節計１０４と信号線１０４ａで接続されている。１３は越流せき４の高さを変えるための駆動装置であり、駆動力伝達手段１３ａで越流せき４と、信号線１２ａで演算器１２と接続されている。その他は図１９と同様である。
【００５９】
次に動作について説明する。調節計１０４では、硝酸性窒素濃度とアンモニア性窒素濃度との差と予め定められた濃度差の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を、例えば式７に従って出力する。
Ｄ_rot＝Ｄ_rot0＋Ｋ_DDN（ＤＮ^*−ＤＮ） ・・・（７）
ここに、
Ｄ_rot ：曝気ロータの浸漬深さの目標値
Ｄ_rot0：定数
Ｋ_DDN ：定数
である。
この演算に必要な硝酸性窒素濃度の計測値は硝酸性窒素濃度計１００の出力として信号線１００ａを介して、またアンモニア性窒素濃度の計測値はアンモニア性窒素濃度計１０１の出力として信号線１０１ａを介して得られる。濃度差の目標値ＤＮ^* は、設定器１０３の出力として信号線１０３ａを介して得られる。調節計１０４の出力Ｄ_rot は信号線１０４ａを介して演算器１２に伝えられる。
演算器１２では、曝気ロータ２の浸漬深さの目標値Ｄ_rot から越流せき４の高さの目標値を、例えば式８に従って演算する。
Ｈ＝Ｈ₀＋Ｄ_rot ・・・（８）
ここに、
Ｈ ：越流せきの高さの目標値
Ｈ₀：定数
である。
演算器１２の出力Ｈは信号線１２ａを介して駆動装置１３に伝えられ、曝気ロータ２の浸漬深さが調節される。
【００６０】
これにより、濃度差ＤＮが目標値ＤＮ^* よりも小さければ、曝気ロータ２の浸漬深さが増加し、好気領域を伸長させる。逆に濃度差ＤＮが目標値ＤＮ^* よりも大きければ、曝気ロータ２の浸漬深さが減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても好気領域の終端がディッチ中央付近にくるように曝気ロータ２の浸漬深さを自動的に調節するので、良好な処理水質を安定して保つことができるようになる。
【００６１】
なお、図２０では調節計１０４の出力である浸漬深さの目標値Ｄ_rot を演算器１２で越流せき４の高さの目標値Ｈに演算する例を示したが、式７および式８の演算を一度に調節計１０４で行い、演算器１２を省略しても同様の効果を奏する。
【００６２】
参考例３．
上記参考例１、２では、硝酸性窒素濃度からアンモニア性窒素濃度を減じたが、アンモニア性窒素濃度から硝酸性窒素濃度を減じても同様の効果を奏する。
【００６３】
参考例４．
本発明に係る他の参考例を図について説明する。図２１は参考例４に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図２１において、１０５は、硝酸性窒素濃度とアンモニア性窒素濃度との濃度比と、予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の回転数の目標値を出力する調節計であり、信号線１００ａで硝酸性窒素濃度計１００と、信号線１０１ａでアンモニア性窒素濃度計１０１と、信号線１０５ａで駆動装置３と接続されている。１０６は濃度比の目標値を設定するための設定器であり、信号線１０６ａで調節計１０５と接続されている。設定器１０６に設定する目標値は、第１の法則より０．１〜１０の範囲、望ましくは１近傍とするとより効果的である。その他は図１９と同様である。
【００６４】
次に、動作について説明する。調節計１０５では、硝酸性窒素濃度とアンモニア性窒素濃度との濃度比と、予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の回転数の目標値を、例えば式９に従って出力する。
Ｒ_rot＝Ｒ_rot0＋Ｋ_RRN1（ＲＮ₁ ^*−ＲＮ₁） ・・・（９）
ここに、
Ｋ_RRN1：定数
ＲＮ₁ ^*：（硝酸性窒素濃度／アンモニア性窒素濃度）の目標値
ＲＮ₁ ：硝酸性窒素濃度／アンモニア性窒素濃度
である。
この演算に必要な硝酸性窒素濃度の計測値は硝酸性窒素濃度計１００の出力として信号線１００ａを介して、またアンモニア性窒素濃度の計測値はアンモニア性窒素濃度計１０１の出力として信号線１０１ａを介して得られる。濃度比の目標値ＲＮ₁ ^*は、設定器１０６の出力として信号線１０６を介して得られる。調節計１０５の出力Ｒ_rot は信号線１０５ａを介して駆動装置３に伝えられ、曝気ロータ２の回転数が調節される。
【００６５】
これにより、濃度比ＲＮ₁ が目標値ＲＮ₁ ^*よりも小さければ、曝気ロータ２の回転数が増加し、好気領域を伸長させる。逆に濃度比ＲＮ₁ が目標値ＲＮ₁ ^*よりも大きければ、曝気ロータ２の回転数が減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても好気領域の終端がディッチ中央付近にくるように曝気ロータ２の回転数を自動的に調節するので、良好な処理水質を安定して保つことができるようになる。
【００６６】
参考例５．
本発明に係る他の参考例を図について説明する。図２２は参考例５に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図２２において、１０７は硝酸性窒素濃度とアンモニア性窒素濃度との比と予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を出力する調節計であり、信号線１００ａで硝酸性窒素濃度計１００と、信号線１０１ａでアンモニア性窒素濃度計１０１と、信号線１０６ａで濃度差の目標値を設定するための設定器１０６と接続されている。参考例４と同様、設定器１０６に設定する目標値は、０．１〜１０の範囲、望ましくは１近傍とするとより効果的である。調節計１０７は信号線１０７ａで曝気ロータ２の浸漬深さの目標値から越流せき４の高さの目標値を演算する演算器１２とも接続されている。その他は図２０と同様である。
【００６７】
次に動作について説明する。調節計１０７では、硝酸性窒素濃度とアンモニア性窒素濃度との濃度比と、予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を、例えば式１０に従って出力する。
Ｄ_rot＝Ｄ_rot0＋Ｋ_DRN1（ＲＮ₁ ^*−ＲＮ₁） ・・・（１０）
ここに、
Ｋ_DRN1：定数
である。
この演算に必要な硝酸性窒素濃度の計測値は硝酸性窒素濃度計１００の出力として信号線１００ａを介して、またアンモニア性窒素濃度の計測値はアンモニア性窒素濃度計１０１の出力として信号線１０１ａを介して得られる。濃度比の目標値ＲＮ₁ ^*は、設定器１０６の出力として信号線１０６ａを介して得られる。調節計１０７の出力Ｄ_rot は信号線１０７ａを介して演算器１２に伝えられる。以下、参考例２と同様、越流せき４の高さを調整して曝気ロータ２の浸漬深さを調節する。
【００６８】
これにより、濃度比ＲＮ₁ が目標値ＲＮ₁ ^*よりも小さければ、曝気ロータ２の浸漬深さが増加し、好気領域を伸長させる。逆に濃度比ＲＮ₁ が目標値ＲＮ₁ ^*よりも大きければ、曝気ロータ２の浸漬深さが減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても好気領域の終端がディッチ中央付近にくるように曝気ロータ２の浸漬深さを自動的に調節するので、良好な処理水質を安定して保つことができるようになる。
【００６９】
なお、図２２では調節計１０７の出力である浸漬深さの目標値を演算器１２で越流せき４の高さの目標値に演算する例を示したが、演算を一度に調節計１０７で行い、演算器１２を省略しても同様の効果を奏する。
【００７０】
参考例６．
上記参考例４、５では、硝酸性窒素濃度をアンモニア性窒素濃度で除したが、アンモニア性窒素濃度を硝酸性窒素濃度で除しても、同様の効果を奏する。
【００７１】
参考例７．
本発明に係る他の参考例を図について説明する。図２３は参考例７に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図２３において、２５は沈澱処理水を放流するための配管ｃに取り付けられた全窒素濃度計である。１０８は、全窒素濃度に対する硝酸性窒素濃度の濃度比と、予め定められた上記濃度比の目標値との偏差に応じて曝気ロータ２の回転数の目標値を出力する調節計であり、信号線２５ａで全窒素濃度計２５と、信号線１００ａで硝酸性窒素濃度計１００と、信号線１０８ａで駆動装置３と接続されている。１０９は濃度比の目標値を設定するための設定器であり、信号線１０９ａで調節計１０８と接続されている。設定器１０９に設定する目標値は、硝酸性窒素濃度とアンモニア性窒素濃度を足したものが全窒素濃度であり、また、第１の法則に示したように、硝酸性窒素濃度とアンモニア性窒素濃度がほぼ等しいとき処理水中の全窒素濃度を最小に抑制することができることから、硝酸性窒素濃度と、全窒素濃度との比が１：１０から９：１０の範囲、最適な比としては１：２になるように設定するとよい。即ち、全窒素濃度に対する硝酸性窒素濃度の濃度比としては、０．１〜０．９の範囲、望ましくは０．２５〜０．７５、最適値としては０．５近傍とすると効果的である。その他は図２１と同様である。
【００７２】
次に、動作について説明する。調節計１０８では、硝酸性窒素濃度と全窒素濃度との濃度比と、予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の回転数の目標値を、例えば式１１に従って出力する。
Ｒ_rot＝Ｒ_rot0＋Ｋ_RRN2（ＲＮ₂ ^*−ＲＮ₂） ・・・（１１）
ここに、
Ｋ_RRN2：定数
ＲＮ₂ ^*：（硝酸性窒素濃度／全窒素濃度）の目標値
ＲＮ₂ ：硝酸性窒素濃度／全窒素濃度
である。
この演算に必要な硝酸性窒素濃度の計測値は硝酸性窒素濃度計１００の出力として信号線１００ａを介して、また全窒素濃度の計測値は全窒素濃度計２５の出力として信号線２５ａを介して得られる。濃度比の目標値ＲＮ₂ ^*は、設定器１０９の出力として信号線１０９を介して得られる。調節計１０８の出力Ｒ_rot は信号線１０８ａを介して駆動装置３に伝えられ、曝気ロータ２の回転数が調節される。
【００７３】
これにより、濃度比ＲＮ₂ が目標値ＲＮ₂ ^*よりも小さければ、曝気ロータ２の回転数が増加し、好気領域を伸長させる。逆に濃度比ＲＮ₂ が目標値ＲＮ₂ ^*よりも大きければ、曝気ロータ２の回転数が減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても好気領域の終端がディッチ中央付近にくるように曝気ロータ２の回転数を自動的に調節するので、良好な処理水質を安定して保つことができるようになる。
【００７４】
参考例８．
本発明に係る他の参考例を図について説明する。図２４は参考例８に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図２４において、１１０は全窒素濃度に対する硝酸性窒素濃度の濃度比と、予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を出力する調節計であり、信号線２５ａで全窒素濃度計２５と、信号線１００ａで硝酸性窒素濃度計１００と、信号線１０９ａで濃度差の目標値を設定するための設定器１０９と接続されている。参考例７と同様、設定器１０９に設定する目標値は、０．１〜０．９の範囲、望ましくは０．２５〜０．７５、最適値としては０．５近傍とすると効果的である。調節計１１０は曝気ロータ２の浸漬深さの目標値から越流せき４の高さの目標値を演算する演算器１２とも接続されている。その他は図２２と同様である。
【００７５】
次に動作について説明する。調節計１１０では、硝酸性窒素濃度と全窒素濃度との濃度比と、予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を、例えば式１２に従って出力する。
Ｄ_rot＝Ｄ_rot0＋Ｋ_DRN2（ＲＮ₂ ^*−ＲＮ₂） ・・・（１２）
ここに、
Ｋ_DRN2：定数
である。
この演算に必要な全窒素濃度の計測値は全窒素濃度計２５の出力として信号線２５ａを介して、また硝酸性窒素濃度の計測値は硝酸性窒素濃度計１００の出力として信号線１００ａを介して得られる。濃度比の目標値ＲＮ₂ ^*は、設定器１０９の出力として信号線１０９ａを介して得られる。調節計１１０の出力Ｄ_rot は信号線１１０ａを介して演算器１２に伝えられる。
【００７６】
これにより、濃度比ＲＮ₂ が目標値ＲＮ₂ ^*よりも小さければ、曝気ロータ２の浸漬深さが増加し、好気領域を伸長させる。逆に濃度比ＲＮ₂ が目標値ＲＮ₂ ^*よりも大きければ、曝気ロータ２の浸漬深さが減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても好気領域の終端がディッチ中央付近にくるように曝気ロータ２の浸漬深さを自動的に調節するので、良好な処理水質を安定して保つことができるという効果を奏する。
【００７７】
なお、図２４では調節計１１０の出力である浸漬深さの目標値Ｄ_rot を演算器１２で越流せき４の高さの目標値に演算する例を示したが、演算を一度に調節計１１０で行い、演算器１２を省略しても同様の効果を奏する。
【００７８】
参考例９．
上記参考例７、８では、硝酸性窒素濃度を全窒素濃度で除したが、全窒素濃度を硝酸性窒素濃度で除しても、同様の効果を奏する。ただし、この時の濃度比の目標値は１〜１０の範囲、望ましくは１．３〜４．０、最適値としては２近傍とすると効果的である。
【００７９】
参考例１０．
本発明に係る他の参考例を図について説明する。図２５は参考例１０に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図２５において、１１１は全窒素濃度に対するアンモニア性窒素濃度の濃度比と、予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の回転数の目標値を出力する調節計であり、信号線２５ａで全窒素濃度計２５と、信号線１０１ａでアンモニア性窒素濃度計１０１と、信号線１１１ａで駆動装置３と接続されている。１１２は濃度比の目標値を設定するための設定器であり、信号線１１２ａで調節計１１１と接続されている。設定器１１２に設定する目標値は、参考例７で述べたと同様に、硝酸性窒素濃度とアンモニア性窒素濃度を足したものが全窒素濃度であり、また、第１の法則に示したように、硝酸性窒素濃度とアンモニア性窒素濃度がほぼ等しいとき処理水中の全窒素濃度を最小に抑制することができることから、アンモニア性窒素濃度と全窒素濃度との比が１：１０から９：１０の範囲、最適な比としては１：２になるように設定するとよい。即ち、全窒素濃度に対するアンモニア性窒素濃度の濃度比としては、０．１〜０．９の範囲、望ましくは０．２５〜０．７５、最適値としては０．５近傍とすると効果的である。その他は図２３と同様である。
【００８０】
次に、動作について説明する。調節計１１１では、アンモニア性窒素濃度と全窒素濃度との濃度比と、予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の回転数の目標値を、例えば式１３に従って出力する。
Ｒ_rot＝Ｒ_rot0−Ｋ_RRN3（ＲＮ₃ ^*−ＲＮ₃） ・・・（１３）
ここに、
Ｋ_RRN3：定数
ＲＮ₃ ^*：（アンモニア性窒素濃度／全窒素濃度）の目標値
ＲＮ₃ ：アンモニア性窒素濃度／全窒素濃度
である。
この演算に必要なアンモニア窒素濃度の計測値はアンモニア性窒素濃度計１０１の出力として信号線１０１ａを介して、また全窒素濃度の計測値は全窒素濃度計２５の出力として信号線２５ａを介して得られる。濃度比の目標値ＲＮ₃ ^*は、設定器１１２の出力として信号線１１２を介して得られる。調節計１１１の出力Ｒ_rot は信号線１１１ａを介して駆動装置３に伝えられ、曝気ロータ２の回転数が調節される。
【００８１】
これにより、濃度比ＲＮ₃ が目標値ＲＮ₃ ^*よりも大きければ、曝気ロータ２の回転数が増加し、好気領域を伸長させる。逆に濃度比ＲＮ₃ が目標値ＲＮ₃ ^*よりも小さければ、曝気ロータ２の回転数が減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても好気領域の終端がディッチ中央付近にくるように曝気ロータ２の回転数を自動的に調節するので、良好な処理水質を安定して保つことができるようになる。
【００８２】
参考例１１．
本発明に係る他の参考例を図について説明する。図２６は参考例１１に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図２６において、１１３は全窒素濃度に対するアンモニア性窒素濃度の濃度比と、予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を出力する調節計であり、信号線２５ａで全窒素濃度計２５と、信号線１０１ａでアンモニア性窒素濃度計１０１と、信号線１１２ａで濃度差の目標値を設定するための設定器１１２と接続されている。調節計１１３は曝気ロータ２の浸漬深さの目標値から越流せき４の高さの目標値を演算する演算器１２とも接続されている。その他は図２４と同様である。
【００８３】
次に動作について説明する。調節計１１３では、アンモニア性窒素濃度と全窒素濃度との濃度比と、予め定められた濃度比の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を、例えば式１４に従って出力する。
Ｄ_rot＝Ｄ_rot0−Ｋ_DRN3（ＲＮ₃ ^*−ＲＮ₃） ・・・（１４）
ここに、
Ｋ_DRN3：定数
である。
この演算に必要な全窒素濃度の計測値は全窒素濃度計２５の出力として、またアンモニア窒素濃度の計測値はアンモニア性窒素濃度計２５の出力として信号線２５ａを介して得られる。濃度比の目標値ＲＮ₃ ^*は、設定器１１２の出力として信号線１１２ａを介して得られる。調節計１１３の出力Ｄ_rot は信号線１１３ａを介して演算器１２に伝えられる。
【００８４】
これにより、濃度比ＲＮ₃ が目標値ＲＮ₃ ^*よりも大きければ、曝気ロータ２の浸漬深さが増加し、好気領域を伸長させる。逆に濃度比ＲＮ₃ が目標値ＲＮ₃ ^*よりも小さければ、曝気ロータ２の浸漬深さが減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても好気領域の終端がディッチ中央付近にくるように曝気ロータ２の浸漬深さを自動的に調節するので、良好な処理水質を安定して保つことができるようになる。
【００８５】
なお、図２６では調節計１１３の出力である浸漬深さの目標値を演算器１２で越流せき４の高さの目標値に演算する例を示したが、演算を一度に調節計１１３で行い、演算器１２を省略しても同様の効果を奏する。
【００８６】
参考例１２．
上記参考例１０、１１では、アンモニア性窒素濃度を全窒素濃度で除したが、全窒素濃度をアンモニア性窒素濃度で除しても同様の効果を奏する。ただし、この時の濃度比の目標値は、参考例９と同様、１〜１０の範囲、望ましくは１．３〜４．０、最適値としては２近傍とすると効果的である。
【００８７】
実施例１．
本発明の請求項１に係る一実施例を図について説明する。図２７は実施例１に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図２７において、８は溶存酸素濃度計であり、曝気ロータ２の設置地点を起点としたディッチ１の中央付近、望ましくは曝気ロータ２の設置地点から流下方向にディッチ長の１／４〜１／２倍だけ離れた地点の溶存酸素濃度を計測する。第３の法則で示したように、窒素除去に対して最適な好気領域と嫌気領域との境界はディッチ中央付近であるため、ディッチ１の中央、ないしやや前方（曝気ロータ２側）の溶存酸素濃度を計測することにより、好気領域の終端がディッチ１の中央付近にくることを確実に検出することができる。曝気ロータ２に近いところの溶存酸素濃度を計測したのでは、流入負荷の変動が大きく溶存酸素濃度の分布が不安定なオキシデーションディッチでは好気領域の終端位置を推測することが難しいし、ディッチ１の中央より後方では、好気領域が短すぎることを検知できないので、曝気ロータ２設置地点から流下方向にディッチ長の１／４〜１／２倍だけ離れた地点の溶存酸素濃度を計測するのが最も適当である。
【００８８】
９は溶存酸素濃度の計測値と、予め定められた溶存酸素濃度の目標値との偏差に応じて曝気ロータ２の回転数の目標値を出力する調節計であり、信号線８ａで溶存酸素濃度計８と、信号線９ａで駆動装置３と接続されている。１０は溶存酸素濃度の目標値を設定するための設定器であり、信号線１０ａで調節計９と接続されている。設定器１０に設定する目標値は、好気領域の終端よりもやや前方の溶存酸素濃度であるから、０［ｍｇ／Ｌ］近傍の値、望ましくは０〜１［ｍｇ／Ｌ］に設定するのが適当である。その他は図４３と同様である。
【００８９】
次に、動作について説明する。曝気ロータ２設置地点から流下方向にディッチ長の１／４〜１／２倍だけ離れた地点の溶存酸素濃度は溶存酸素濃度計８で計測される。溶存酸素濃度の計測値は信号線８ａを介して調節計９に伝えられる。調節計９では、溶存酸素濃度の計測値と、予め定められた溶存酸素濃度の目標値との偏差に応じて曝気ロータ２の回転数の目標値を、例えば式１５に従って出力する。
Ｒ_rot＝Ｒ_rot0＋Ｋ_RDO（ＤＯ^*−ＤＯ） ・・・（１５）
ここに、
Ｋ_RDO ：定数
ＤＯ^* ：溶存酸素濃度の目標値
ＤＯ ：溶存酸素濃度の計測値
である。
この演算に必要な溶存酸素濃度の目標値ＤＯ^* は、設定器１０の出力として信号線１０ａを介して得られる。調節計９の出力Ｒ_rot は信号線９ａを介して駆動装置３に伝えられ、曝気ロータ２の回転数が調節される。
【００９０】
これにより、溶存酸素濃度の計測値ＤＯが目標値ＤＯ^* よりも小さければ、曝気ロータ２の回転数が増加し、好気領域を伸長させる。逆に溶存酸素濃度の計測値ＤＯが目標値ＤＯ^* よりも大きければ、曝気ロータ２の回転数が減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても、好気領域の終端がディッチ中央付近にくるように曝気ロータ２の回転数を自動的に調節するので、窒素濃度の計測や分析を行わずに良好な処理水質を安定して保つことができるという効果を奏する。
【００９１】
実施例２．
本発明の請求項１に係る他の実施例を図について説明する。図２８は実施例２に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図２８において、１１は曝気ロータ２設置地点から流下方向にディッチ長の１／４〜１／２倍だけ離れた地点の溶存酸素濃度の計測値と、予め０［ｍｇ／Ｌ］近傍に設定された溶存酸素濃度の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を出力する調節計であり、信号線８ａで溶存酸素濃度計８と、信号線１０ａで溶存酸素濃度の目標値を設定するための設定器１０と接続されている。１２は曝気ロータ２の浸漬深さの目標値から越流せき４の高さの目標値を演算する演算器であり、調節計１１と信号線１１ａで接続されている。１３は越流せき４の高さを変えるための駆動装置であり、駆動力伝達手段１３ａで越流せき４と、信号線１２ａで演算器１２と接続されている。その他は図２７と同様である。
【００９２】
次に動作について説明する。調節計１１では、溶存酸素濃度の計測値と予め定められた溶存酸素濃度の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を、例えば式１６に従って出力する。
Ｄ_rot＝Ｄ_rot0＋Ｋ_DDO（ＤＯ^*−ＤＯ） ・・・（１６）
ここに、
Ｋ_DDO ：定数
である。
この演算に必要な溶存酸素濃度の計測値ＤＯは溶存酸素濃度計８の出力として信号線８ａを介して、また溶存酸素濃度の目標値ＤＯ^* は設定器１０の出力として信号線１０ａを介して得られる。調節計１１の出力Ｄ_rotは信号線１１ａを介して演算器１２に伝えられる。
【００９３】
演算器１２の出力は信号線１２ａを介して駆動装置１３に伝えられ、曝気ロータ２の回転数が調節される。
【００９４】
これにより、溶存酸素濃度の計測値ＤＯが目標値ＤＯ^* よりも小さければ、曝気ロータ２の浸漬深さが増加し、好気領域を伸長させる。逆に溶存酸素濃度の計測値ＤＯが目標値ＤＯ^* よりも大きければ、曝気ロータ２の浸漬深さが減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても好気領域の終端がディッチ中央付近にくるように曝気ロータ２の浸漬深さを自動的に調節するので、窒素濃度の計測や分析を行わずに良好な処理水質を安定して保つことができるという効果を奏する。
【００９５】
なお、図２８では調節計１１の出力である浸漬深さの目標値を演算器１２で越流せき４の高さの目標値に演算する例を示したが、演算を一度に調節計１１で行い、演算器１２を省略しても同様の効果を奏する。
【００９６】
実施例３．
本発明の請求項２に係る一実施例を図について説明する。図２９は実施例３に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図２９において、１４は溶存酸素濃度の計測値と曝気ロータ２の回転数とからディッチ１内溶存酸素濃度が予め定められた溶存酸素濃度の基準値に達する地点を演算する演算器であり、信号線８ａで溶存酸素濃度計８と、信号線２ａで曝気ロータ２と接続されている。溶存酸素濃度計８は、ディッチ１の中央付近よりも前方、すなわち曝気ロータ設置地点を起点としたディッチの中央付近までの範囲、望ましくは曝気ロータ２の設置地点から流下方向にディッチ長の０〜１／２倍だけ離れた地点までの範囲に設置する。なぜなら、溶存酸素濃度計８での計測値を起点とした溶存酸素濃度分布を演算し、好気領域の終端がディッチ１の中央付近にくるように曝気ロータ２の回転数を調節することが目的だからである。１５は溶存酸素濃度の基準値を設定するための設定器であり、信号線１５ａで演算器１４と接続されている。設定器１５に設定する基準値は、好気領域の終端を示す溶存酸素濃度であるから、０［ｍｇ／Ｌ］近傍の値、望ましくは０〜１［ｍｇ／Ｌ］に選択するのが適当である。１６はディッチ１内溶存酸素濃度が基準値に達する地点の演算値（演算地点）と、当該地点の目標値（目標地点）との偏差に応じて曝気ロータ２の回転数の目標値を出力する調節計であり、信号線１４ａで演算器１４と、信号線１６ａで曝気ロータ２の駆動装置３と接続されている。１７は当該地点の目標値を設定するための設定器であり、信号線１７ａで調節計１６と接続されている。設定器１７に設定する目標値は、第３の法則よりディッチ１の中央付近とするのがよいから、曝気ロータ２設置地点から流下方向にディッチ長の１／４〜３／４倍だけ離れた地点までの範囲から選択するのが適当である。その他は図２７と同様である。
【００９７】
次に、動作について説明する。演算器１４では、例えば式１７に従ってディッチ１内溶存酸素濃度が予め定められた溶存酸素濃度の基準値に達する地点の、溶存酸素濃度計８設置地点からの流下方向の距離を演算する。
ｘ＝（ＤＯ−ＤＯ^**）／Ｒ_r×Ｖ（Ｒ_rot） ・・・（１７）
ここに、

である。
この演算に必要な溶存酸素濃度の計測値ＤＯは溶存酸素濃度計８の出力として信号線８ａを介して、また曝気ロータ２の回転数Ｒ_rot は曝気ロータ２の出力として信号線２ａを介して得られる。溶存酸素濃度の基準値ＤＯ^**は設定器１５の出力として信号線１５ａを介して得られる。演算結果ｘは信号線１４ａを介して調節計１６に伝えられる。なお、ディッチ１内混合液の循環流速Ｖ（Ｒ_rot） は、曝気ロータ２の回転数Ｒ_rot より求めずに流速計を用いて直接計測してもよい。
調節計１６では、例えば式１８に従ってディッチ１内溶存酸素濃度が基準値に達する地点の演算値ｘと当該地点の目標値との偏差に応じて曝気ロータ２の回転数の目標値を出力する。
Ｒ_rot＝Ｒ_rot0＋Ｋ_Rx（ｘ^*−ｘ） ・・・（１８）
ここに、
Ｋ_Rx：定数
ｘ^* ：ディッチ１内溶存酸素濃度が予め定められた溶存酸素濃度の基準値に達する地点の、溶存酸素濃度計８設置地点からの流下方向の距離の目標値である。
この演算に必要なディッチ１内の溶存酸素濃度が基準値に達する地点の目標値ｘ^* は設定器１７の出力として信号線１７ａを介して得られる。調節計１６の出力Ｒ_rot は信号線１６ａを介して駆動装置３に伝えられ、曝気ロータ２の回転数が調節される。
【００９８】
これにより、溶存酸素濃度が基準値に達する地点の演算値ｘが目標値ｘ^* よりも小さければ、曝気ロータ２の回転数が増加し、好気領域を伸長させる。逆に溶存酸素濃度が基準値に達する地点の演算値ｘが目標値ｘ^* よりも大きければ、曝気ロータ２の回転数が減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても好気領域の終端がディッチ中央付近にくるように曝気ロータ２の回転数を自動的に調節するので、窒素濃度の計測や分析を行わずに良好な処理水質を安定して保つことができるという効果を奏する。
【００９９】
実施例４．
本発明の請求項２に係る他の実施例を図について説明する。図３０は実施例４に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図３０において、８および１８は曝気ロータ２設置地点から流下方向にディッチ長の０〜１／２倍だけ離れた地点までの範囲に設置された２本の溶存酸素濃度計である。１９は溶存酸素濃度８、１８の計測値からディッチ１内溶存酸素濃度が０［ｍｇ／Ｌ］近傍の値に予め設定された溶存酸素濃度の基準値に達する地点を演算する演算器であり、信号線８ａで溶存酸素濃度計８と、信号線１８ａで溶存酸素濃度計１８と、信号線１５ａで溶存酸素濃度の基準値を設定するための設定器１５と接続されている。演算器１９は信号線１９ａで曝気ロータ２の回転数を出力する調節計１６とも接続されている。その他は図２９と同様である。
【０１００】
次に、動作について説明する。演算器１９では、例えば式１９に従ってディッチ１内溶存酸素濃度が予め定められた溶存酸素濃度の基準値に達する地点の溶存酸素濃度計８設置地点からの流下方向の距離を演算する。
ｘ＝Ｌ×（ＤＯ１−ＤＯ^**）／（ＤＯ１−ＤＯ２） ・・・（１９）
ここに、
Ｌ ：溶存酸素濃度計８と溶存酸素濃度計１８との距離
ＤＯ１：溶存酸素濃度計８による計測値
ＤＯ２：溶存酸素濃度計１８による計測値
である。
この演算に必要な溶存酸素濃度の計測値ＤＯ１、ＤＯ２は溶存酸素濃度計８および溶存酸素濃度計１８の出力として信号線８ａおよび信号線１８ａを介して得られる。溶存酸素濃度の基準値ＤＯ^**は設定器１５の出力として信号線１５ａを介して得られる。また、演算結果ｘは信号線１９ａを介して調節計１６に伝えられ、以下、実施例３と同様にして曝気ロータ２の回転数が調節される。
【０１０１】
この実施例では、実施例３の効果に加えて、好気領域の終端の位置を直接溶存酸素濃度の分布から演算するので、より緻密に曝気ロータ２の回転数の調節を行うことができるという効果がある。
【０１０２】
実施例５．
本発明の請求項２に係るさらに他の実施例を図について説明する。図３１は実施例５に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図３１において、２０は演算器１４で演算された、ディッチ１内溶存酸素濃度が０［ｍｇ／Ｌ］近傍の値に予め設定された基準値に達する地点の演算値と、ディッチ１内の曝気ロータ２設置地点から流下方向にディッチ長の１／４〜３／４倍だけ離れた地点までの範囲に予め設定された当該地点の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を出力する調節計であり、信号線１４ａで演算器１４と接続されている。演算器１４は実施例３と同様、溶存酸素濃度計８の計測値と曝気ロータ２の回転数とからディッチ１内溶存酸素濃度が基準値に達する地点を演算するものである。調節計２０は信号線１７ａで当該地点の目標値を設定するための設定器１７と、信号線２０ａで曝気ロータ２の浸漬深さの目標値から越流せき４の高さの目標値を演算するための演算器１２とも接続されている。その他は図２９と同様である。
【０１０３】
次に、動作について説明する。調節計２０では、ディッチ１内溶存酸素濃度が基準値に達する地点の演算値と、当該地点の目標値との偏差に応じて曝気ロータ２の浸漬深さの目標値を、例えば式２０に従って出力する。
Ｄ_rot＝Ｄ_rot0＋Ｋ_Dx（ｘ^*−ｘ） ・・・（２０）
ここに、
Ｋ_Dx：定数
である。
この演算に必要なディッチ１内溶存酸素濃度が基準値に達する地点の演算値ｘは演算器１４の出力として信号線１４ａを介して、また当該地点の目標値ｘ^* は設定器１７の出力として信号線１７を介して得られる。演算結果Ｄ_rot は信号線２０ａを介して演算器１２に伝えられる。
【０１０４】
これにより、溶存酸素濃度が基準値に達する地点の演算値ｘが目標値ｘ^* よりも小さければ、曝気ロータ２の浸漬深さが増加し、好気領域を伸長させる。逆に溶存酸素濃度が基準値に達する地点の演算値ｘが目標値ｘ^* よりも大きければ、曝気ロータ２の浸漬深さが減少し、好気領域を短縮させる。すなわち、ディッチ１への流入負荷が変動しても好気領域の終端がディッチ中央付近にくるように曝気ロータ２の浸漬深さを自動的に調節するので、窒素濃度の計測や分析を行わずに良好な処理水質を安定して保つことができるという効果を奏する。
【０１０５】
なお、図３１では調節計２０の出力である浸漬深さの目標値を演算器１２で越流せき４の高さの目標値に演算する例を示したが、演算を一度に調節計２０で行い、演算器１２を省略しても同様の効果を奏する。
【０１０６】
実施例６．
実施例５では溶存酸素濃度の計測値と曝気ロータ２の回転数から溶存酸素濃度が予め定めた基準値になる地点を推定する例を示したが、実施例４で示したように２つ以上の溶存酸素濃度計を用いて直接溶存酸素濃度の分布を求め、溶存酸素濃度が予め定めた基準値になる地点を演算してもよい。この場合の実施例の装置構成は図３０とほぼ同様であるが、調節計１６および駆動装置３のかわりに調節計２０、演算器１２および駆動装置１３で曝気ロータ２の浸漬深さを調節する。これにより、実施例５の効果に加えて、より緻密に曝気ロータ２の浸漬深さの調節を行うことができるという効果を奏する。
【０１０７】
実施例７．
本発明の請求項３に係る一実施例を図について説明する。図３２は実施例７に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図３２において、２１はディッチ１内の活性汚泥微生物の濃度を計測する微生物濃度計であり、ディッチ１内の任意の地点に設置される。２２は曝気ロータ２設置地点から流下方向にディッチ長の１／４〜１／２倍だけ離れた地点の溶存酸素濃度の目標値を演算する演算器であり、微生物濃度計２１と信号線２１ａで、調節計９と信号線２２ａで接続されている。２３は溶存酸素濃度の基準値を設定する設定器であり、信号線２３ａで演算器２２と接続されている。その他は図２７と同様である。
【０１０８】
次に、動作について説明する。第４の法則でも述べたように、ＭＬＳＳ濃度（活性汚泥微生物濃度）が高いほどディッチ内の溶存酸素濃度分布は急勾配となる。すなわち、好気領域の終端よりもやや前方の溶存酸素濃度は、活性汚泥微生物濃度が高いときはやや大きめになり、活性汚泥微生物濃度が低いときはやや小さめになる。そこで、演算器２２では、例えば式２１によって溶存酸素濃度の目標値を補正する。
ＤＯ^* _H＝ＤＯ^*＋Ｋ_SS（ＭＬＳＳ−ＭＬＳＳ₀） ・・・（２１）
ここに、
ＤＯ^* _H ：補正した溶存酸素濃度目標値（活性汚泥微生物濃度を考慮した補正値）
ＤＯ^* ：溶存酸素濃度目標値
Ｋ_SS ：定数
ＭＬＳＳ ：活性汚泥微生物濃度の計測値
ＭＬＳＳ₀：活性汚泥微生物濃度の基準値
である。
この演算に必要な活性汚泥微生物濃度の計測値ＭＬＳＳは微生物濃度計２１の出力として信号線２１ａを介して、また溶存酸素濃度の目標値ＤＯ^* は設定器２３の出力として信号線２３ａを介して得られる。演算結果ＤＯ^* _Hは信号線２２ａを介して曝気ロータ２の回転数の目標値を出力する調節計９に伝えられ、以下、図２７に示す実施例１と同様に動作する。
【０１０９】
これにより、活性汚泥微生物濃度の計測値ＭＬＳＳが基準値ＭＬＳＳ₀ よりも大きいとき、曝気ロータ２から流下方向にディッチ長の１／４〜１／２倍だけ離れた地点の溶存酸素濃度の目標値ＤＯ^* は大きめに補正される。よって、溶存酸素濃度分布が急勾配となることに対応できる。逆に、活性汚泥微生物濃度の計測値ＭＬＳＳが基準値ＭＬＳＳ₀ よりも小さいとき、溶存酸素濃度の目標値ＤＯ^* は小さめに補正される。よって、溶存酸素濃度分布が緩勾配となることに対応できる。すなわち、実施例１の効果に加えて、「ＭＬＳＳ濃度が高いほどディッチ内の溶存酸素濃度分布は急勾配となる」という第４の法則を考慮した、より正確な好気領域の調節を行なうことができるという効果を奏する。
【０１１０】
実施例８．
実施例７では曝気ロータ２の回転数を調節する例を示したが、曝気ロータ２の浸漬深さを調節してもよい。この場合の実施例の装置構成は図３２とほぼ同様であるが、調節計９および駆動装置３のかわりに調節計１１、演算器１２および駆動装置１３で曝気ロータ２の浸漬深さを調節する。演算器１２は省略することもできる。これにより、実施例２の効果に加えて、「ＭＬＳＳ濃度が高いほどディッチ内の溶存酸素濃度分布は急勾配となる」という第４の法則を考慮した、より正確な好気領域の調節を行なうことができるという効果を奏する。
【０１１１】
実施例９．
本発明の請求項４に係る一実施例を図について説明する。図３３は実施例９に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図３３において、２４は溶存酸素濃度の計測値、曝気ロータ２の回転数および活性汚泥微生物濃度の計測値から、ディッチ１内溶存酸素濃度が、０［ｍｇ／Ｌ］近傍の値に予め設定された溶存酸素濃度の基準値に達する地点を演算する演算器であり、信号線８ａで溶存酸素濃度計８と接続されている。溶存酸素濃度計８は曝気ロータ２設置地点から流下方向にディッチ長の０〜１／２倍だけ離れた地点までの範囲に設置される。演算器２４は信号線２ａで曝気ロータ２と、信号線１５ａで溶存酸素濃度の基準値を設定するための設定器１５とも接続されている。また、信号線２１ａで微生物濃度計２１と、信号線２４ａで曝気ロータ２の回転数の目標値を出力する調節計１６とも接続されている。その他は図２９と同様である。
【０１１２】
次に、動作について説明する。演算器２４では、例えば式１７および式２２によってディッチ１内溶存酸素濃度が予め定められた溶存酸素濃度の基準値に達する地点を演算する。
ｘ_H＝ｘ×Ｒｒ₀／Ｒｒ（ＭＬＳＳ）
Ｒｒ（ＭＬＳＳ）＝Ｒｒ₀＋Ｋ_MLSS（ＭＬＳＳ−ＭＬＳＳ₀） ・・・（２２）
ここに、

である。
式２２の演算に必要な活性汚泥微生物濃度の計測値ＭＬＳＳは微生物濃度計２１の出力として信号線２１ａを介して得られる。演算結果ｘ_H は信号線２４ａを介して曝気ロータ２の回転数の目標値を出力する調節計１６に伝えられ、以下、図２９に示す実施例３と同様に動作する。
【０１１３】
これにより、活性汚泥微生物濃度の計測値ＭＬＳＳが大きいとき溶存酸素消費速度の項Ｒｒ（ＭＬＳＳ）が大きくなるので、基準値到達地点の距離ｘ_H は距離ｘに対し短めに補正される。よって、溶存酸素濃度分布が急勾配となることに対応できる。逆に、活性汚泥微生物濃度の計測値ＭＬＳＳが小さいときは溶存酸素消費速度の項Ｒｒ（ＭＬＳＳ）が小さくなるので、基準値到達地点の距離ｘ_H は距離ｘに対し長めに補正される。よって、溶存酸素濃度分布が緩勾配となることに対応できる。すなわち、実施例３の効果に加えて、「ＭＬＳＳ濃度が高いほどディッチ内の溶存酸素濃度分布は急勾配となる」という第４の法則を考慮した、より正確な好気領域の調節を行なうことができるという効果を奏する。
【０１１４】
実施例１０．
上記実施例９では曝気ロータ２の回転数を調節する例を示したが、曝気ロータ２の浸漬深さを調節してもよい。この場合の実施例の装置構成は図３３とほぼ同様であるが、調節計１６および駆動装置３のかわりに調節計２０、演算器１２および駆動装置１３で曝気ロータ２の浸漬深さを調節する。演算器１２は省略することもできる。これにより、実施例５の効果に加えて、「ＭＬＳＳ濃度が高いほどディッチ内の溶存酸素濃度分布は急勾配となる」という第４の法則を考慮した、より正確な好気領域の調節を行なうことができるという効果を奏する。
【０１１５】
実施例１１．
本発明の請求項７に係る一実施例を図について説明する。図３４は実施例１１に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図３４において、２５は沈澱処理水を放流するための配管ｃに取り付けられた全窒素濃度計である。２６はディッチ１内のＭＬＳＳ濃度と処理水中の全窒素濃度との関係を記憶させてある記憶回路であり、信号線２５ａで全窒素濃度計２５と接続されている。演算器２２は曝気ロータ２設置地点から流下方向にディッチ長の１／４〜１／２倍だけ離れた地点の溶存酸素濃度の目標値を演算するものである。２７は処理水中の全窒素濃度の目標値を設定する設定器であり、信号線２７ａで記憶回路２６と接続されている。２８は記憶回路２６より出力されるＭＬＬＳ濃度の目標値とＭＬＳＳ濃度の計測値との偏差に応じて余剰汚泥引き抜き量を出力する調節計であり、信号線２６ａで記憶回路２６と、信号線２１ｂで微生物濃度（ＭＬＳＳ濃度）計２１と、信号線２８ａで余剰汚泥引き抜きポンプ６と接続されている。その他は図３２と同様である。
【０１１６】
次に、動作について説明する。処理水中の全窒素濃度は配管ｃに取り付けられた全窒素濃度計２５で計測される。全窒素濃度の計測値は信号線２５ａを介して記憶回路２６に伝えられる。記憶回路２６では処理水中の全窒素濃度の計測値と、予め定められた全窒素濃度の目標値とからディッチ１内のＭＬＳＳ濃度の目標値を決定する。処理水中の全窒素濃度の目標値は設定器２７により設定される。目標値は１個だけでもよいし、上限値と下限値の２個を設定してもよい。ここでは説明を簡潔にするために前者の場合について述べる。設定された目標値は信号線２７ａにより記憶回路２６に伝えられる。
【０１１７】
さて、記憶回路２６にはディッチ１内のＭＬＳＳ濃度と処理水中の全窒素濃度との関係が記憶させてある。即ち、窒素を高度に除去するためには、ＭＬＳＳ濃度を高く保つ必要がある（第２の法則）ことが示されたが、図３５は最適な水質を得る一例であり、横軸はディッチ１内のＭＬＳＳ濃度［ｍｇ／Ｌ］を、縦軸は処理水中の全窒素濃度［ｍｇ／Ｌ］を示す。図中の曲線は、ある流入負荷に対しロータ条件をかえてシミュレーションした結果のうち、最も処理水質が良好だったときの全窒素濃度とＭＬＳＳ濃度の関係を示している。図３５に従い、処理水中の全窒素濃度の計測値と予め定められた目標値とからディッチ１内のＭＬＳＳ濃度の目標値を決定するアルゴリズムを説明する。
【０１１８】
計画値どおりの流量、例えば図３５では１５［ｍ³ ／ｈ］の下水が流入するとき、目標値どおりの処理水質が得られるようにＭＬＳＳ濃度が設定してある（Ａ点）。全窒素濃度計測値が目標値よりも悪い場合は、流入流量が増加しているはずである。そこで、全窒素濃度の計測値と最初に設定された現在のＭＬＳＳ濃度との組み合わせから、流入流量を推定する（Ｂ点）。例えば図３５では２０［ｍ³ ／ｈ］となる。この新しい流入流量をパラメータとしたＭＬＳＳ濃度−全窒素濃度曲線に従い、目標水質を得るための新しいＭＬＳＳ濃度目標値を決定する（Ｃ点）。全窒素濃度の計測値が目標値よりも良好な場合も、同様に新しいＭＬＳＳ濃度目標値を決定することができる。この新しいＭＬＳＳ濃度目標値は調節計２８に伝えられる。調節計２８では、例えば式２３に従って余剰汚泥引き抜き量の目標値を出力する。
Ｑ_drw＝Ｑ_drw0＋Ｋ_SS（ＭＬＳＳ^*−ＭＬＳＳ） ・・・（２３）
ここに、
Ｑ_drw ：余剰汚泥引き抜き量の目標値
Ｑ_drw0 ：定数
Ｋ_SS ：定数
ＭＬＳＳ^*：ディッチ１内ＭＬＳＳ濃度の目標値（新しいＭＬＳＳ）
である。
【０１１９】
前述したように、ディッチ１内ＭＬＳＳ濃度の目標値ＭＬＳＳ^* は記憶回路２６の出力として信号線２６ａを介して得られる。また、ディッチ１内ＭＬＳＳ濃度の計測値ＭＬＳＳは信号線２１ｂを介して微生物濃度計２１より得られる。調節計２８の出力は信号線２８ａを介して余剰汚泥引き抜きポンプ６に伝えられ、所定量で余剰汚泥が引き抜かれる。
【０１２０】
これにより、目標水質を達成するために最適なＭＬＳＳ濃度が維持される。一方、曝気ロータ２の回転数はＭＬＳＳ濃度計２１の計測値による補正を行いながら調節されるので、実施例７の効果に加えて、さらに安定して良好な処理水質が得られると同時に系内の活性汚泥微生物量に過不足が生じないという効果を奏する。
【０１２１】
実施例１２．
本発明の請求項７に係る他の実施例を図について説明する。図３６は実施例１２に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図３６において、２９は全窒素濃度計２５の計測値と予め定められた目標値との偏差に応じてディッチ１内ＭＬＳＳ濃度の目標値を演算する演算器であり、信号線２５ａで配管ｃに取り付けられた全窒素濃度計２５と、信号線２７ａで全窒素濃度の目標値を設定するための設定器２７と、信号線２９ａで余剰汚泥引き抜き量の調節計２８と接続されている。その他は図３４と同様である。
【０１２２】
次に、動作について説明する。演算器２９では、例えば式２４に従ってディッチ１内ＭＬＳＳ濃度の目標値を出力する。
ＭＬＳＳ^*＝ＭＬＳＳ₀＋Ｋ_TN1（ＴＮ^*−ＴＮ） ・・・（２４）
ここに、
ＭＬＳＳ₀：定数
Ｋ_TN1 ：定数
ＴＮ^* ：全窒素濃度の目標値
ＴＮ ：全窒素濃度の計測値
である。
この演算に必要な全窒素濃度の目標値ＴＮ^* は、設定器２７の出力として信号線２７ａを介して、また全窒素濃度の計測値ＴＮは全窒素濃度計２５の出力として信号線２５ａを介して得られる。演算結果ＭＬＳＳ^* は信号線２９ａを介して調節計２８に伝えられる。
【０１２３】
これにより、全窒素濃度の計測値ＴＮが目標値ＴＮ^* よりも大きければ、余剰汚泥引き抜き量が減少し、系内に保持される汚泥総量が増加する。よってディッチ１内のＭＬＳＳ濃度が増加するので、処理水中の全窒素濃度は低減する方向に向かう。逆に全窒素濃度の計測値ＴＮが目標値ＴＮ^* よりも小さければ、余剰汚泥引き抜き量が増加し、系内に保持される汚泥総量は減少する。一方、曝気ロータ２の回転数はＭＬＳＳ濃度計２１の計測値による補正を行いながら調節される。すなわち、目標水質を達成するために最適なＭＬＳＳ濃度が維持され、そのＭＬＳＳ濃度に対して最適な好気領域長になるように曝気ロータ２の回転数が調節されるので、実施例１１と同様の効果を奏する。なお、本実施例ではＭＬＳＳ濃度の目標値ＭＬＳＳ^* を、演算によって求めているので、記憶回路２６を用いた実施例２３のものより簡単な構成となる。
【０１２４】
実施例１３．
上記実施例１１、１２では、最適化されたＭＬＳＳ濃度の基準値とＭＬＳＳ濃度の計測値を用いてディッチ内の特定区間の溶存酸素濃度の制御目標値を補正する例に対して、目標水質を達成するために最適なＭＬＳＳ濃度を演算し、このＭＬＳＳ濃度の目標値になるように汚泥の引き抜き量をコントロールしたが、補正を行なわないものであってもよい。この場合の実施例の装置構成として、図３４、図３６中の演算器２２、設定器２３を省略するかわりに設定器１０を具備し、溶存酸素濃度目標値の設定を設定器１０で行う構成が考えられる。これにより、実施例１１、１２よりも簡単な装置構成でほぼ同様の効果を奏する。また、これに類似する装置構成として、図１９〜図２６に微生物濃度計２１、記憶回路２６、設定器２７および調節計２８を具備し、全窒素濃度計２５、もしくは硝酸性窒素濃度計１００およびアンモニア性窒素濃度計１０１からの出力信号を用いて余剰汚泥引き抜き量の調節を行うという構成が考えられる。これにより、目標水質を達成するために最適なＭＬＳＳ濃度が維持されると同時に、好気領域長の制御も適切に行われるので、参考例１〜１２の効果に加えて、さらに安定して良好な処理水質が得られると同時に系内の活性汚泥微生物量に過不足が生じないという効果を奏する。
【０１２５】
実施例１４．
本発明の請求項７に係るさらに他の実施例を図について説明する。図３７は実施例１４に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図３７において、記憶回路２６と演算器２２は信号線２６ｂで接続されている。上記実施例１１では計測されたＭＬＳＳ濃度を用いてディッチ内の特定区間の溶存酸素濃度の制御目標値を補正する例に対して、目標水質を達成するために最適なＭＬＳＳ濃度を演算し、このＭＬＳＳ濃度の目標値になるように汚泥の引き抜き量をコントロールしたが、計測されるＭＬＳＳ濃度はいずれ上記ＭＬＳＳ濃度の目標値になるので、本実施例１４では記憶回路２６より出力されるＭＬＳＳ濃度の目標値ＭＬＳＳ^* を、計測されＭＬＳＳ濃度の代わりに演算器２２に入力し、溶存酸素濃度の目標値の補正を行った。
このようにすることにより、水処理を行うための微生物量に過不足がないように素早く対処できる。
【０１２６】
実施例１５．
実施例１２に対しても実施例１４と同様、演算器２９より出力されるＭＬＳＳ濃度の目標値ＭＬＳＳ^* を演算器２２に入力し、溶存酸素濃度の目標値の補正の際に、計測されるＭＬＳＳ濃度の代わりに用いてもよい。
【０１２７】
実施例１６．
本発明の請求項８に係る一実施例を図について説明する。図３８は実施例１６に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図３８において、３０は全窒素濃度計２５の計測値と予め定められた全窒素濃度目標値との偏差に応じて余剰汚泥引き抜き量の目標値を出力する調節計であり、信号線２５ａで配管ｃに取り付けられた全窒素濃度計２５と、また信号線３０ａで余剰汚泥引き抜きポンプ６と接続されている。２７は全窒素濃度の目標値を設定する設定器であり、信号線２７ａで調節計３０と接続されている。その他は図３２と同様である。
【０１２８】
次に、動作について説明する。調節計３０では、例えば式２５に従って余剰汚泥引き抜き量の目標値を出力する。
Ｑ_drw＝Ｑ_drw0＋Ｋ_drw（ＴＮ^*−ＴＮ） ・・・（２５）
ここに、
Ｋ_TN2：定数
である。
この演算に必要な全窒素濃度の目標値ＴＮ^* は、設定器２７の出力として信号線２７ａを介して、また全窒素濃度の計測値ＴＮは全窒素濃度計２５の出力として信号線２５ａを介して得られる。演算結果Ｑ_drw は信号線３０ａを介して余剰汚泥引き抜きポンプ６に伝えられる。
【０１２９】
これにより、全窒素濃度の計測値ＴＮが目標値ＴＮ^* よりも大きければ、余剰汚泥引き抜き量が減少し、系内に保持される汚泥総量が増加する。よってディッチ１内のＭＬＳＳ濃度が増加するので、処理水中の全窒素濃度は低減する方向に向かう。逆に全窒素濃度の計測値ＴＮが目標値ＴＮ^* よりも小さければ、余剰汚泥引き抜き量が増加し、系内に保持される汚泥総量は減少する。一方、曝気ロータ２の回転数はＭＬＳＳ濃度計２１の計測値による補正を行いながら調節される。すなわち、目標水質を達成するために最適なＭＬＳＳ濃度が維持され、そのＭＬＳＳ濃度に対して最適な好気領域長になるように曝気ロータ２の回転数が調節されるので、実施例７の効果に加えて、さらに安定して良好な処理水質が得られると同時に系内の活性汚泥微生物量に過不足が生じないという効果を奏する。
【０１３０】
実施例１７．
上記実施例１６では、最適化されたＭＬＳＳ濃度の基準値を用いてディッチ内の特定区間の溶存酸素濃度の制御目標値を補正する例に対して、目標水質を達成するように汚泥の引き抜き量をコントロールしたが、補正を行なわないものであってもよい。この場合の実施例の装置構成として、図３８中の微生物濃度計２１、演算器２２、設定器２３を省略するかわりに設定器１０を具備し、溶存酸素濃度目標値の設定を設定器１０で行う構成が考えられる。これにより、実施例１６よりも簡単な装置構成でほぼ同様の効果を奏する。また、これに類似する装置構成として、図１９〜図２６に設定器２７および調節計３０を具備し、全窒素濃度計２５、もしくは硝酸性窒素濃度計１００およびアンモニア性窒素濃度計１０１からの出力信号を用いて余剰汚泥引き抜き量の調節を行うという構成が考えられる。これにより、目標水質を達成するために最適なＭＬＳＳ濃度が維持されると同時に、好気領域長の制御も適切に行われるので、参考例１〜１２の効果に加えて、さらに安定して良好な処理水質が得られると同時に系内の活性汚泥微生物量に過不足が生じないという効果を奏する。
【０１３１】
実施例１８．
上記実施例１１〜１７では、曝気ロータ２の回転数を調節する例を示したが、曝気ロータ２の浸漬深さを調節してもよい。この場合の実施例の装置構成は図３４、３６、３７、３８とほぼ同様であるが、調節計９および駆動装置３のかわりに調節計１１、演算器１２および駆動装置１３で曝気ロータ２の浸漬深さを調節する。演算器１２は省略することもできる。これにより、実施例２あるいは実施例８の効果に加えてさらに安定して良好な処理水質が得られると同時に系内の活性汚泥微生物量に過不足が生じないという効果を奏する。
【０１３２】
実施例１９．
実施例１１〜１８では、ディッチ１内の特定区間の溶存酸素濃度の計測値を用いて曝気ロータ２の回転数もしくは浸漬深さを調節する例を示したが、実施例３〜６、９、１０のように溶存酸素濃度が予め定めた基準値になる地点を推定し、これが常時所定の地点にあるように曝気ロータ２の回転数あるいは浸漬深さを調節するやり方でもよい。この場合の実施例の装置構成は図３４、３６、３７、３８とほぼ同様であるが、例えば回転数の調節を行う場合、その部分の構成が図３３のようになる。浸漬深さの調節を行う場合は、調節計１６および駆動装置３のかわりに調節計２０、演算器１２および駆動装置１３で曝気ロータ２の浸漬深さを調節する。演算器１２は省略することもできる。これにより、実施例３〜６、９、１０の効果に加えてさらに安定して良好な処理水質が得られると同時に系内の活性汚泥微生物量に過不足が生じないという効果を奏する。
【０１３３】
実施例２０．
実施例１１〜１９では、処理水中の全窒素濃度を計測する例を示したが、処理水の水質を示す指標であればこれに限らず、有機物濃度や全リン濃度などを計測してもよい。
【０１３４】
実施例２１．
参考例１〜１２、実施例１１〜２０では、硝酸性窒素濃度計１００やアンモニア性窒素濃度計１０１等の処理水質を計測する手段を沈澱処理水を放流するための配管ｃに設置する例を示したが、これら濃度計の設置順はどちらが先でも良い。また、上記処理水質を計測する手段はディッチ１からの流出水を沈澱池５に導入するための配管ｂ、もしくはディッチ１内の処理水流出地点付近に設置してもよい。
【０１３５】
実施例２２．
本発明の請求項５に係る一実施例を図について説明する。図３９は実施例２２に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図３９において、３１はディッチ１内の水温を計測する温度計であり、ディッチ内の任意の地点に設置される。３２は曝気ロータ２設置地点から流下方向にディッチ長の１／４〜１／２倍だけ離れた地点の溶存酸素濃度の目標値を演算する演算器であり、温度計３１と信号線３１ａで、調節計９と信号線３２ａで接続されている。３３は溶存酸素濃度の目標値を演算するためのパラメータを設定する設定器であり、信号線３３ａで演算器３２と接続されている。その他は図２７と同様である。
【０１３６】
次に、動作について説明する。第３の法則でも述べたように、処理水質に対して最適な好気領域の終端位置は水温、ｐＨ、酸化還元電位など微生物活性に影響を与える因子の変動の影響を受ける。詳細には、硝化速度が脱窒速度に対して大きいとき前方（曝気ロータ側）にずれ、脱窒速度が硝化速度に対して大きいとき後方にずれる。そこで、演算器３２では、例えば式２６に従って溶存酸素濃度の目標値を演算する。
ＤＯ_H1 ^*＝ＤＯ^*×Ｋ_Dθ_D ^T-20／Ｋ_Nθ_N ^T-20 ・・・（２６）
ここに、
ＤＯ_H1 ^* ：溶存酸素濃度目標値（水温を考慮した補正値）
Ｋ_D ：水温２０゜Cのときの脱窒速度
θ_D ：定数
Ｋ_N ：水温２０゜Cのときの硝化速度
θ_N ：定数
Ｔ ：温度
である。
この演算に必要なディッチ１内の水温Ｔは温度計３１の出力として信号線３１ａを介して、また演算のためのパラメータは設定器３３の出力として信号線３３ａを介して得られる。演算結果ＤＯ_H1 ^*は信号線３２ａを介して曝気ロータ２の回転数の目標値を出力する調節計９に伝えられる。
【０１３７】
これにより、脱窒速度が硝化速度に対して大きいとき曝気ロータ２から流下方向にディッチ長の１／４から１／２倍だけ離れた地点の溶存酸素濃度の目標値は大きめに補正される。よって、処理水質に対して最適な好気領域の終端位置がディッチ中央付近よりも後方にずれることに対応できる。逆に、硝化速度が脱窒速度に対して大きいとき溶存酸素濃度の目標値は小さめに補正される。よって処理水質に対して最適な好気領域の終端位置がディッチ中央付近よりも後方にずれることに対応できる。すなわち、実施例１の効果に加えて、「処理水質に対して最適な好気領域の終端位置は水温、ｐＨ、酸化還元電位など微生物活性に影響を与える因子の変動の影響を受ける」という第３の法則を考慮した、より正確な好気領域の調節を行なうことができるという効果を奏する。
【０１３８】
実施例２３．
実施例２２では曝気ロータ２の回転数を調節する例を示したが、曝気ロータ２の浸漬深さを調節してもよい。この場合の実施例の装置構成は図３９とほぼ同様であるが、調節計９および駆動装置３のかわりに調節計１１、演算器１２および駆動装置１３で曝気ロータ２の浸漬深さを調節する。演算器１２は省略することもできる。これにより、実施例２の効果に加えて、「処理水質に対して最適な好気領域の終端位置は水温、ｐＨ、酸化還元電位など微生物活性に影響を与える因子の変動の影響を受ける」という第３の法則を考慮した、より正確な好気領域の調節を行なうことができるという効果を奏する。
【０１３９】
実施例２４．
本発明の請求項６に係る一実施例を図について説明する。図４０は実施例２４に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図４０において、３４は溶存酸素濃度の計測値、曝気ロータ２の回転数およびディッチ１内の水温の計測値とからディッチ１内溶存酸素濃度が０［ｍｇ／Ｌ］近傍の値に予め設定された溶存酸素濃度の基準値に達する地点を演算する演算器であり、信号線８ａで溶存酸素濃度計８と接続されている。溶存酸素濃度計８は曝気ロータ２設置地点から流下方向にディッチ長の０〜１／２倍だけ離れた地点までの範囲に設置される。演算器３４は信号線２ａで曝気ロータ２と、信号線１５ａで溶存酸素濃度の基準値を設定するための設定器１５とも接続されている。また、信号線３１ａで温度計３１と、信号線３４ａで曝気ロータ２の回転数の目標値を出力する調節計１６とも接続されている。その他は図２９と同様である。
【０１４０】
次に、動作について説明する。演算器３４では、例えば式１７および式２７によってディッチ１内溶存酸素濃度が予め定められた溶存酸素濃度の基準値に達する地点を演算する。
Ｘ_H2＝Ｘ×Ｋ_Dθ_D ^T-20／Ｋ_Nθ_N ^T-20 ・・・（２７）
ここに、
Ｘ_H2：ディッチ１内溶存酸素濃度が予め定められた溶存酸素濃度の基準値に達する地点の溶存酸素濃度計８設置地点からの流下方向の距離（水温を考慮した補正値）
である。
式２７の演算に必要な活性汚泥微生物濃度の計測値は微生物濃度計３１の出力として信号線３１ａを介して得られる。演算結果Ｘ_H2は信号線３４ａを介して曝気ロータ２の回転数の目標値を出力する調節計１６に伝えられる。
【０１４１】
これにより、脱窒速度が硝化速度に対して大きいとき溶存酸素濃度の基準値到達地点の距離Ｘ_H2は距離Ｘに対して長めに補正される。よって、処理水質に対して最適な好気領域の終端位置がディッチ中央付近よりも後方にずれることに対応できる。逆に、硝化速度が脱窒速度に対して大きいとき溶存酸素濃度の基準値到達地点の距離Ｘ_H2は距離Ｘに対して短めに補正される。よって処理水質に対して最適な好気領域の終端位置がディッチ中央付近よりも後方にずれることに対応できる。すなわち、実施例３の効果に加えて、「処理水質に対して最適な好気領域の終端位置は水温、ｐＨ、酸化還元電位など微生物活性に影響を与える因子の変動の影響を受ける」という第３の法則を考慮した、より正確な好気領域の調節を行なうことができるという効果を奏する。
【０１４２】
実施例２５．
実施例２４では曝気ロータ２の回転数を調節する例を示したが、曝気ロータ２の浸漬深さを調節してもよい。この場合の実施例の装置構成は図４０とほぼ同様であるが、調節計１６および駆動装置３のかわりに調節計２０、演算器１２および駆動装置１３で曝気ロータ２の浸漬深さを調節する。演算器１２は省略することもできる。これにより、実施例５の効果に加えて、「処理水質に対して最適な好気領域の終端位置は水温、ｐＨ、酸化還元電位など微生物活性に影響を与える因子の変動の影響を受ける」という第３の法則を考慮した、より正確な好気領域の調節を行なうことができるという効果を奏する。
【０１４３】
実施例２６．
実施例２２〜２５ではディッチ１内の特定区間の溶存酸素濃度の目標値を水温のみを考慮して補正する例を示したが、実施例７〜２１のようにＭＬＳＳ濃度を考慮した補正も同時に行うやり方でもよい。この場合の実施例の装置構成は図３２、３３あるいは図３４、３６とほぼ同様であるが、水温計３１からの信号を信号線３１ａを介して演算器２２に入力し、例えば式２８によって曝気ロータ２設置地点から流下方向にディッチ長の１／４〜１／２倍だけ離れた地点の溶存酸素濃度の目標値を演算する。
ＤＯ_H2 ^*＝ＤＯ_H ^*×Ｋ_Dθ_D ^T-20／Ｋ_Nθ_N ^T-20 ・・・（２８）
【０１４４】
あるいは水温計３１からの信号を信号線３１ａを介して演算器２４に入力し、例えば式２９によってディッチ１内溶存酸素濃度が予め定められた溶存酸素濃度の基準値に達する地点を演算する。
Ｘ_H2＝Ｘ_H×Ｋ_Dθ_D ^T-20／Ｋ_Nθ_N ^T-20 ・・・（２９）
【０１４５】
また、曝気ロータ２の浸漬深さの調節を行う場合は調節計９または１６、および駆動装置３のかわりに調節計１１または２０、演算器１２、および駆動装置１３で構成する。演算器１２は省略することもできる。
【０１４６】
これにより、実施例７〜２１の効果に加えて、「処理水質に対して最適な好気領域の終端位置は水温、ｐＨ、酸化還元電位など微生物活性に影響を与える因子の変動の影響を受ける」という第３の法則を考慮した、より正確な好気領域の調節を行なうことができるという効果を奏する。
【０１４７】
実施例２７．
実施例２２〜２６では温度計を用いる例を示したが、ｐＨ計あるいは酸化還元電位計を用いても同様の効果を奏する。この場合式２６〜２９で示した演算の代わりに、ｐＨあるいは酸化還元電位が硝化速度と脱窒速度とに与える影響を考慮した演算を行う。
【０１４８】
実施例２８．
本発明の請求項９に係る一実施例を図について説明する。図４１は実施例２８に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図４１において、３５は下水をディッチ１に導入するための配管ａに取り付けられた流量計である。３６は曝気ロータ２の回転数の基準値を演算する演算器であり、信号線３５ａで流量計３５と、信号線３５ａで曝気ロータ２の回転数の目標値を演算する調節計９と接続されている。その他は図２７と同様である。
【０１４９】
次に、動作について説明する。実施例１で示したように、ディッチ１内の特定区間内の溶存酸素濃度を計測し、この計測値を用いて曝気ロータ２の回転数を調節することにより計測地点の溶存酸素濃度を一定に保つようにすれば、ディッチ１内に好気領域と嫌気領域とを適切に形成することができ、良好な処理水質を得ることができる。ただし、この方法では、槽内での生物化学的反応が進み溶存酸素濃度に変化が生じて初めて曝気ロータの調節が行われるので、急激な流入負荷変動のあったときに、対応が遅れる可能性がある。よってディッチ１に流入する下水の流量を計測し、この計測値を用いて予め曝気ロータ２の回転数の基準値を調節しておいた上で、好気領域と嫌気領域のバランスの調節を行うようにすれば、急激な流入流量の変動に対しても安定して良好な処理水質を保つことができる。
【０１５０】
ディッチ１に流入する下水の流量は配管ａに取り付られた流量計３５で計測され、信号線３５ａを介して演算器３６に伝えられる。演算器３６では、例えば式３０によって曝気ロータ２の回転数の基準値Ｒ_rot0が演算される。
Ｒ_rot0＝Ｋ_QinＱ_in ・・・（３０）
ここに、
Ｋ_Qin：定数
Ｑ_in ：ディッチ１に流入する下水の流量
である。
この演算結果は信号線３５ａを介して曝気ロータ２の回転数の目標値を演算する調節計９に伝えられる。
【０１５１】
これにより、流入流量が大きいとき曝気ロータ２の回転数の基準値が予め大きめに設定される。逆に、流入流量が小さいとき曝気ロータ２の回転数の基準値が予め小さめに設定される。これにより、実施例１３の効果に加えて、急激な流入流量の変動に対しても安定して良好な処理水質を保つことができるという効果を奏する。
【０１５２】
実施例２９．
実施例２８では曝気ロータ２の回転数を調節する例を示したが、曝気ロータ２の浸漬深さを調節してもよい。この場合の実施例の装置構成は図４１とほぼ同様であるが、調節計９および駆動装置３のかわりに調節計１１、演算器１２および駆動装置１３で構成し、演算器３４の演算結果（曝気ロータ２の浸漬深さの基準値）を調節計１１に入力する。演算器１２は省略することもできる。これにより、実施例２の効果に加えて、急激な流入流量の変動に対しても安定して良好な処理水質を保つことができるという効果を奏する。
【０１５３】
実施例３０．
実施例２８、２９ではディッチ１内の特定区間の溶存酸素濃度の計測値を用いて曝気ロータ２の回転数もしくは浸漬深さを調節する例を示したが、溶存酸素濃度が予め定めた基準値になる地点を推定し、これが常時所定の地点にあるように曝気ロータ２の回転数もしくは浸漬深さを調節するやり方、さらに微生物濃度や温度、ｐＨ、酸化還元電位などの微生物活性を考慮して溶存酸素濃度あるいは基準値到達点を補正するやり方、もちろん硝酸性窒素濃度、アンモニア性窒素濃度および全窒素濃度の濃度差や濃度比を用いて曝気ロータ２の回転数もしくは浸漬深さを調節するやり方でも同様の効果を奏する。これらの場合の実施例の装置構成は、図４１同様、流量計３５ならびに演算器３６を具備すればよく、演算器３６の演算結果を曝気ロータ２の回転数調節計あるいは浸漬深さ調節計に入力する。
【０１５４】
実施例３１．
実施例２８〜３０ではディッチ１への下水の流入流量の計測値を用いる例を示したが、ディッチ１からの流出流量の計測値を用いても同様の効果を奏する。
【０１５５】
実施例３２．
実施例２８〜３０ではディッチ１への下水の流入流量の計測値を用いる例を示したが、流入汚濁物、例えば全窒素の濃度の計測値を用いても同様の効果を奏する。
【０１５６】
実施例３３．
実施例２８〜３０ではディッチ１への下水の流入流量の計測値を用いる例を示したが、これに流入汚濁物、例えば全窒素の濃度を乗じた流入全窒素量を用いても同様の効果を奏する。
【０１５７】
参考例１３．
本発明に係る参考例を図について説明する。図４２は参考例１３に係るオキシデーションディッチ水処理装置の制御装置を示す構成図である。図４２において、３７はディッチ１からの流出水を沈澱池５に導入するための配管ｂに取り付けられた流量計である。３８は越流せき４の高さの目標値を出力する調節計であり、信号線３７ａで流量計３７と、信号線３８ａで越流せき４の駆動装置１３と接続されている。その他は図４３と同様である。
【０１５８】
次に、動作について説明する。ディッチ１から流出する流量は配管ｂに取り付られた流量計３７で計測され、信号線３７ａを介して調節計３８に伝えられる。調節計３８では、例えば式３１によって越流せき４の高さの目標値が演算される。
Ｈ＝Ｈ₀＋Ｋ_Qout（Ｑ_out−Ｑ_out0） ・・・（３１）
ここに、
Ｋ_Qout：係数
Ｑ_out ：ディッチ１から流出する流量
Ｑ_out0：ディッチ１から流出する流量の基準値
である。
この演算結果Ｈは信号線３８ａを介して駆動装置１３に伝えられ、越流せき４の高さが調節される。
【０１５９】
これにより、ディッチ１から流出する流量Ｑ_out が基準値Ｑ_out0よりも大きければ、越流せき４の高さＨが高くなり、流出量すなわち沈澱池５への流入量が低減されると同時に、曝気ロータ２の浸漬深さが増し曝気量が増加する。逆に、ディッチ１から流出する流量Ｑ_out が基準値Ｑ_out0よりも小さければ、越流せき４の高さＨが低くなり、流出量すなわち沈澱池５への流入量が増加すると同時に、曝気ロータ２の浸漬深さが減り曝気量が低減する。つまり、ディッチ１に流入する下水の流量が変動しても、沈澱池５に流出する流量は常に一定に保たれ、沈澱池５では固液分離処理が良好に行われるという効果を奏する。さらに、曝気ロータ２の浸漬深さも同時に調節できるという効果を奏する。
【０１６０】
実施例３４．
上記実施例および参考例のうち、曝気ロータの浸漬深さを調節する例では、越流せきの高さを変える場合について述べたが、曝気ロータ自体の設置位置を変更するようにしても同様の効果を奏する。
【０１６１】
なお、以上述べた各実施例および参考例では、曝気ロータを用いる場合について示したが、その他の曝気装置、例えば軸流ポンプ型曝気装置、スクリュー型曝気装置などを用いる場合にも適用できる。
【０１６２】
また、上記各実施例および参考例では、窒素を除去する場合について示したが、その他の汚濁物、例えば有機物あるいはリンを除去する場合にも適用できる。
【０１６３】
さらに、上記各実施例および参考例では、時間連続のアナログ式で構成したが、時間不連続のアナログ式（サンプル値式）やデジタル式で構成しても同様の効果を奏する。
【０１６４】
また、上記実施例および参考例では、制御回路構成を示したが、これを計算機内にプログラム化して実装しても同様の効果を奏する。
【０１６５】
また、上記実施例でおよび参考例は、制御回路を閉ループで構成したが、制御目標値をオペレータに提示する運転支援システムとして構成することもできる。
【０１６６】
【発明の効果】
以上のように、請求項１の発明によればオキシデーションディッチ水処理装置の制御装置を、曝気装置のディッチ内での設置地点から流下方向にディッチ長の１／４〜１／２倍離れた領域の任意の地点の溶存酸素濃度を計測する手段、上記溶存酸素濃度の計測値と、０〜１［ｍｇ／リットル］の値に予め設定された上記溶存酸素濃度の目標値との偏差に応じて、上記曝気装置の上記ディッチ内での設置地点と上記ディッチ内の被処理水流出地点との中央付近に好気領域と嫌気領域との境界がくるように、上記曝気装置の回転数または浸漬深さの目標値を出力する調節計、及び上記回転数または上記浸漬深さの目標値に従い、上記曝気装置の回転数または浸漬深さを調節する調節手段を備えた構成としたので、窒素濃度の計測や分析を行わなくても好気領域の終端がディッチ中央付近にくるように自動的に調節することができ、良好な処理水質を安定して保つことができるという効果がある。
【０１６７】
また、請求項２の発明によればオキシデーションディッチ水処理装置の制御装置を、曝気装置のディッチ内での設置地点から流下方向にディッチ長の０〜１／２倍離れた範囲に設置された少なくとも１つ以上の溶存酸素濃度計測手段、この溶存酸素濃度計測手段で計測された溶存酸素濃度の計測値を用いて、ディッチ内溶存酸素濃度が、０［ｍｇ／リットル］近傍の値に予め設定された溶存酸素濃度の基準値に達する地点を演算する演算手段、この演算手段で演算された演算値と、上記曝気装置の上記ディッチ内での設置地点と上記ディッチ内の被処理水流出地点との中央付近に予め設定された、上記基準値に達する地点の目標値との偏差に応じて、上記曝気装置の上記ディッチ内での設置地点と上記ディッチ内の被処理水流出地点との中央付近に好気領域と嫌気領域との境界がくるように、上記曝気装置の回転数または浸漬深さの目標値を出力する調節計、及び上記回転数または上記浸漬深さの目標値に従い、上記曝気装置の回転数または浸漬深さを調節する調節手段を備えた構成としたので、窒素濃度の計測や分析を行わなくても好気領域の終端がディッチ中央付近にくるように曝気ロータの回転数を自動的に調節することができ、良好な処理水質を安定して保つことができるという効果がある。
【０１６８】
また、請求項３の発明によればディッチ内の任意の地点の活性汚泥微生物濃度の計測値、または活性汚泥微生物濃度の目標値より、溶存酸素濃度の目標値を補正するようにしたので、より正確な好気領域の調節ができ、良好な処理水質を安定して保つことができるという効果がある。
【０１６９】
また、請求項４の発明によればディッチ内の任意の地点の活性汚泥微生物濃度の計測値、または活性汚泥微生物濃度の目標値より、溶存酸素濃度の基準値に達する地点を補正するようにしたので、より正確な好気領域の調節ができ、良好な処理水質を安定して保つことができるという効果がある。
【０１７０】
また、請求項５の発明によれば、ディッチ内の任意の地点に水温、ｐＨ、酸化還元電位の少なくとも一つを計測する手段を設け、これらの計測値より溶存酸素濃度の目標値を補正するようにしたので、より正確な好気領域の調節ができ、良好な処理水質を安定して保つことができるという効果がある。
【０１７１】
また、請求項６の発明によれば、ディッチ内の任意の地点に水温、ｐＨ、酸化還元電位の少なくとも一つを計測する手段を設け、これらの計測値より溶存酸素濃度の基準値に達する地点の目標値を補正するようにしたので、より正確な好気領域の調節ができ、良好な処理水質を安定して保つことができるという効果がある。
【０１７２】
また、請求項７の発明によればオキシデーションディッチ水処理装置の制御装置を、ディッチ内の任意の地点に設置された活性汚泥微生物の濃度を計測する手段と、処理水の水質を計測する手段と、水質の計測値と予め定められた目標値との偏差に応じて活性汚泥微生物濃度の目標値を演算する演算器と、活性汚泥微生物濃度の目標値と計測値との偏差に応じて汚泥引き抜き量の目標値を出力する調節計と、汚泥引き抜き量の目標値に従い汚泥引き抜き量を調節する手段とを具備するようにしたので、ディッチ内に好気領域と嫌気領域とを適切に形成すると同時に、水処理を行うための微生物量に過不足が生じないという効果がある。
【０１７３】
また、請求項８の発明によればオキシデーションディッチ水処理装置の制御装置を、処理水の水質を計測する手段と、水質の計測値と予め定められた目標値との偏差に応じて汚泥引き抜き量の目標値を演算する調節計と、汚泥引き抜き量の目標値に従い汚泥引き抜き量を調節する手段とを具備するようにしたので、ディッチ内に好気領域と嫌気領域とを適切に形成すると同時に、水処理を行うための微生物量に過不足が生じないという効果がある。
【０１７４】
また、請求項９の発明によればオキシデーションディッチ水処理装置の制御装置を、ディッチへの流入負荷を計測する手段と、流入負荷の計測値より曝気ロータの回転数もしくは浸漬深さの基準値のフィードフォワード量を演算する手段とを具備するようにしたので、良好な処理水質をより安定して保つことができるという効果がある。
【図面の簡単な説明】
【図１】 本発明に係わる第１〜４の法則を発見するに至った計算機シミュレーションに用いた槽列モデルを示す説明図である。
【図２】 ＭＬＳＳ濃度を３０００［ｍｇ／Ｌ］、曝気ロータ浸漬深さを１５［ｃｍ］と設定して計算機シミュレーションを行なった結果を示すグラフである。
【図３】 ＭＬＳＳ濃度を３０００［ｍｇ／Ｌ］、曝気ロータ浸漬深さを２０［ｃｍ］と設定して計算機シミュレーションを行なった結果を示すグラフである。
【図４】 ＭＬＳＳ濃度を３０００［ｍｇ／Ｌ］、曝気ロータ浸漬深さを２４［ｃｍ］と設定して計算機シミュレーションを行なった結果を示すグラフである。
【図５】 ＭＬＳＳ濃度を４０００［ｍｇ／Ｌ］、曝気ロータ浸漬深さを１５［ｃｍ］と設定して計算機シミュレーションを行なった結果を示すグラフである。
【図６】 ＭＬＳＳ濃度を４０００［ｍｇ／Ｌ］、曝気ロータ浸漬深さを２０［ｃｍ］と設定して計算機シミュレーションを行なった結果を示すグラフである。
【図７】 ＭＬＳＳ濃度を４０００［ｍｇ／Ｌ］、曝気ロータ浸漬深さを２４［ｃｍ］と設定して計算機シミュレーションを行なった結果を示すグラフである。
【図８】 ＭＬＳＳ濃度を５０００［ｍｇ／Ｌ］、曝気ロータ浸漬深さを１５［ｃｍ］と設定して計算機シミュレーションを行なった結果を示すグラフである。
【図９】 ＭＬＳＳ濃度を５０００［ｍｇ／Ｌ］、曝気ロータ浸漬深さを２０［ｃｍ］と設定して計算機シミュレーションを行なった結果を示すグラフである。
【図１０】 ＭＬＳＳ濃度を５０００［ｍｇ／Ｌ］、曝気ロータ浸漬深さを２４［ｃｍ］と設定して計算機シミュレーションを行なった結果を示すグラフである。
【図１１】 Ｆ点での硝酸性窒素濃度とアンモニア性窒素濃度との差と、全窒素濃度との関係を示すグラフである。
【図１２】 硝化速度を１０倍に設定して計算機シミュレーションを行なった結果を示すグラフである。
【図１３】 硝化速度を１０倍に設定して計算機シミュレーションを行なった結果を示すグラフである。
【図１４】 硝化速度を１０倍に設定して計算機シミュレーションを行なった結果を示すグラフである。
【図１５】 脱窒速度を１０倍に設定して計算機シミュレーションを行なった結果を示すグラフである。
【図１６】 脱窒速度を１０倍に設定して計算機シミュレーションを行なった結果を示すグラフである。
【図１７】 脱窒速度を１０倍に設定して計算機シミュレーションを行なった結果を示すグラフである。
【図１８】 Ａ点での溶存酸素濃度とＦ点での全窒素濃度との関係を示すグラフである。
【図１９】 本発明の参考例１によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図２０】 本発明の参考例２によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図２１】 本発明の参考例４によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図２２】 本発明の参考例５によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図２３】 本発明の参考例７によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図２４】 本発明の参考例８によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図２５】 本発明の参考例１０によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図２６】 本発明の参考例１１によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図２７】 本発明の実施例１によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図２８】 本発明の実施例２によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図２９】 本発明の実施例３によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図３０】 本発明の実施例４によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図３１】 本発明の実施例５によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図３２】 本発明の実施例７によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図３３】 本発明の実施例９によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図３４】 本発明の実施例１１によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図３５】 本発明の実施例１１によるオキシデーションディッチ水処理装置の制御装置の記憶回路２６に記憶されるＭＬＳＳ濃度と全窒素濃度との関係を示すグラフである。
【図３６】 本発明の実施例１２によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図３７】 本発明の実施例１４によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図３８】 本発明の実施例１６によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図３９】 本発明の実施例２２によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図４０】 本発明の実施例２４によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図４１】 本発明の実施例２８によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図４２】 本発明の参考例１３によるオキシデーションディッチ水処理装置の制御装置を示す構成図である。
【図４３】 従来のオキシデーションディッチ水処理装置を示す構成図である。
【符号の説明】
１ ディッチ
２ 曝気ロータ
３ 駆動装置
４ 越流せき
５ 沈澱池
６ ポンプ
８、１８ 溶存酸素濃度計
９、１１、１６、２０、２８、３０、３８、１０２、１０４、１０７、１０８、１１０、１１１、１１３ 調節計
１０、１５、１７、２３、２７、３３、１０３、１０６、１０９、１１２ 設定器
１２、１４、１９、２２、２４、２９、３２、３４、３６ 演算器
１３ 駆動装置
２１ 微生物濃度計
２５ 全窒素濃度計
２６ 記憶回路
３１ 温度計
３５、３７ 流量計
１００ 硝酸性窒素濃度計
１０１ アンモニア性窒素濃度計[0001]
[Industrial application fields]
The present invention relates to a control device for an oxidation ditch water treatment device, and more particularly to a control device for efficiently removing nitrogen components in sewage, which is a causative substance of eutrophication in a water treatment process.
[0002]
[Prior art]
As described in "Technical data on the oxidation ditch method" (Japan Sewerage Corporation Technical Development Department / Sewerage Corporation Business Promotion Association, January 1986), the oxidation ditch water treatment method Sedimentation of general sewage, mainly sewage, and sewage after screen treatment are treated with activated sludge using a non-terminal water channel (ditch) with a mechanical aeration device as a reaction tank. In continuous treatment, suspended substances in the final sedimentation basin It is a series of sewage treatment methods that remove water.
[0003]
In recent years, closed water areas, which are water supply sources, are eutrophic and red tides and musty odor microorganisms are frequently bred. Therefore, the removal of nitrogen in sewage and wastewater, which is the causative substance, is required. In the oxidation ditch method, an aerobic region where dissolved oxygen exists and an anaerobic region where there is no dissolved oxygen are formed spatially (flow direction) in the ditch, and the nitrification reaction proceeds in an aerobic state and proceeds in an anaerobic state. In combination with the denitrification reaction, nitrogen in sewage can be removed.
[0004]
FIG. 43 is a configuration diagram illustrating an example of a conventional oxidation ditch water treatment apparatus. In FIG. 43, 1 is a ditch and 2 is an aeration rotor. Reference numeral 3 denotes a driving device for the aeration rotor, which is connected to the aeration rotor 2 by a driving force transmission means 3a. 4 is overflow cough. Reference numeral 13 denotes a driving device for changing the height of the overflow basin 4 and is connected to the overflow basin 4 by a driving force transmission means 13a. 5 is a sedimentation basin, 6 is a pump for discharging excess sludge, and 7 is a pump for returning sludge to the ditch 1. 8 is a dissolved oxygen concentration meter installed at an arbitrary point in the ditch. Further, a is a pipe for introducing sewage into the ditch 1, b is a pipe for introducing the effluent from the ditch 1 into the settling basin 5, c is a pipe for discharging the settling water, and d is a settling pond. A pipe for extracting more sludge, e is a pipe for discharging the sludge extracted by the pump 6 as surplus sludge, and f is a pipe for circulating the sludge returned to the ditch 1 by the pump 7.
[0005]
Next, the operation will be described. Sewage is introduced into the ditch 1 via the pipe a. In the ditch 1, oxygen necessary for the treatment is supplied by the aeration rotor 2, and the inflowing sewage and the activated sludge in the ditch 1 are mixed and stirred, and a flow rate is given to the mixed liquid to circulate in the ditch 1. Adjustment of the oxygen supply amount by the aeration rotor 2 is performed by changing the rotation speed or immersion depth of the aeration rotor 2. The rotation speed of the aeration rotor 2 is changed by operating the driving device 3, and the immersion depth is changed by operating the driving device 13 of the overflow overflow 4.
The dissolved oxygen concentration meter 8 measures the dissolved oxygen concentration in the ditch 1. The operation manager of the water treatment apparatus appropriately adjusts the rotation speed or the immersion depth of the aeration rotor 2 while observing the measured values. If these adjustments are successful and an aerobic region and an anaerobic region are properly formed in the ditch 1, nitrogen in the sewage is well removed.
[0006]
On the other hand, the mixed liquid treated with activated sludge is introduced into the sedimentation basin 5 through the pipe b. In the sedimentation basin 5, solid-liquid separation of the activated sludge mixed liquid is performed. The supernatant water is discharged through the pipe c. The concentrated sludge is drawn out through the pipe d. Part of the sludge is discharged out of the system by the pump 6 through the pipe e as surplus sludge, and part is returned to the ditch 1 by the pump 7 through the pipe f as return sludge.
[0007]
[Problems to be solved by the invention]
As described above, conventionally, the operation manager has adjusted the rotational speed and immersion depth of a mechanical aeration apparatus, for example, an aeration rotor, with reference to the measured value of the dissolved oxygen concentration in the ditch. However, since the flow rate and properties of general sewage, mainly domestic sewage, vary significantly, the aerobic and anaerobic conditions are appropriately formed in the ditch according to the fluctuations, ensuring good water quality at all times. There was a problem that it was difficult to do.
[0008]
In addition, when the inflow to the ditch increases, the outflow to the sedimentation basin also increases, so the solid-liquid separation of the activated sludge mixture cannot be performed sufficiently, and it is difficult to always ensure good water quality. was there.
[0009]
The present invention has been made to solve such problems, and by appropriately controlling the rotational speed or immersion depth of the oxidation ditch water treatment device or the amount of sludge extraction, the nitrogen component in the sewage is controlled. It aims at obtaining the control apparatus of the oxidation ditch water treatment apparatus which can always remove favorably and can ensure the favorable water quality.
In addition, for the purpose of obtaining a control device for an oxidation ditch water treatment device that can properly perform solid-liquid separation treatment by appropriately controlling the flow rate flowing out to the sedimentation basin and always ensure good water quality. Yes.
[0010]
[Means for Solving the Problems]
  The control apparatus of the oxidation ditch water treatment apparatus according to claim 1 of the present invention is an aeration apparatus.Within the ditchMeans for measuring the dissolved oxygen concentration at an arbitrary point in a region that is 1/4 to 1/2 times as long as the ditch length in the flow direction from the installation point, the measured value of the dissolved oxygen concentration, and 0 to 1 [mg / liter] According to the deviation from the target value of the dissolved oxygen concentration set in advance to the value ofthe aboveAeration equipmentIn the above ditchInstallation point andIn the above ditchA controller that outputs a target value of the rotational speed or immersion depth of the aeration apparatus so that the boundary between the aerobic region and the anaerobic region is near the center of the treated water outflow point, and the rotational speed or the immersion According to the depth target value, there is provided adjusting means for adjusting the rotational speed or immersion depth of the aeration apparatus.
[0011]
  The control apparatus for the oxidation ditch water treatment apparatus according to claim 2 of the present invention is an aeration apparatus.Within the ditchAt least one or more dissolved oxygen concentration measuring means installed in the range of 0 to 1/2 times the ditch length in the downstream direction from the installation point, and the measured value of the dissolved oxygen concentration measured by this dissolved oxygen concentration measuring means A calculating means for calculating a point where the dissolved oxygen concentration in the ditch reaches a reference value of the dissolved oxygen concentration set in advance to a value in the vicinity of 0 [mg / liter], a calculated value calculated by the calculating means, the aboveThe installation point of the aeration apparatus in the ditch and the outflow point of treated water in the ditchPreset near the center ofReach the above reference valueDepending on the deviation from the target value of the point,the aboveAeration equipmentIn the above ditchInstallation point andIn the above ditchA controller that outputs a target value of the rotational speed or immersion depth of the aeration apparatus so that the boundary between the aerobic region and the anaerobic region is near the center of the treated water outflow point, and the rotational speed or the immersion According to the depth target value, there is provided adjusting means for adjusting the rotational speed or immersion depth of the aeration apparatus.
[0012]
Claims of the invention3The control device of the oxidation ditch water treatment apparatus according to the present invention corrects the target value of the dissolved oxygen concentration from the measured value of the activated sludge microorganism concentration measured at an arbitrary point in the ditch or the target value of the activated sludge microorganism concentration. A correction means is provided.
[0013]
Claims of the invention4The control device for the oxidation ditch water treatment device in accordance with the above is that the measured value of the activated sludge microbial concentration measured at any point in the ditch or the target value of the activated sludge microbial concentration reaches the reference value of the dissolved oxygen concentration. With correction means to correct the target valueis there.
[0014]
Claims of the invention5The control device of the oxidation ditch water treatment apparatus according to the present invention is a means for measuring at least one of water temperature, pH, oxidation-reduction potential installed at an arbitrary point in the ditch, and from these measured values, the target of dissolved oxygen concentration A correction means for correcting the value is provided.
[0015]
Claims of the invention6The control device of the oxidation ditch water treatment apparatus according to the present invention is a means for measuring at least one of water temperature, pH, oxidation-reduction potential installed at an arbitrary point in the ditch, and based on these measured values, a reference for dissolved oxygen concentration A correction means for correcting the target value at the point reaching the value is provided.
[0016]
The control apparatus of the oxidation ditch water treatment apparatus according to claim 7 of the present invention is a means for measuring the quality of treated water, the measured value of water quality and a predetermined target value of water quality. An arithmetic unit that calculates a target value of the activated sludge microbial concentration according to the deviation, and an adjustment that outputs the target value of the sludge extraction amount according to the deviation between the target value of the activated sludge microbial concentration and the measured value of the activated sludge microbial concentration. And an adjusting means for adjusting the sludge extraction amount according to the target value of the sludge extraction amount.
[0017]
The control apparatus of the oxidation ditch water treatment apparatus according to claim 8 of the present invention is a means for measuring the quality of treated water, and the amount of sludge withdrawn according to the deviation between the measured value of the water quality and a predetermined target value of the water quality And an adjusting means for adjusting the sludge extraction amount according to the target value of the sludge extraction amount.
[0018]
Claims of the invention9The control apparatus for the oxidation ditch water treatment apparatus according to the present invention includes means for measuring the inflow load into the ditch, and means for calculating the feedforward amount of the reference value of the rotation speed or immersion depth of the aeration apparatus from the measured value of the inflow load Withis there.
[0019]
[Action]
Claim 1The control device of the oxidation ditch water treatment apparatus according to the present invention measures the dissolved oxygen concentration in a specific section in the ditch, and adjusts the rotational speed or immersion depth of the aeration rotor using this measurement value, thereby measuring the measurement point. The dissolved oxygen concentration is kept constant, and an aerobic region and an anaerobic region are appropriately formed in the ditch.
[0020]
Claim2The control device of the oxidation ditch water treatment apparatus according to the present invention measures the dissolved oxygen concentration in a specific section in the ditch, and uses this measured value to estimate the point where the dissolved oxygen concentration becomes a predetermined reference value. By adjusting the rotation speed or immersion depth of the aeration rotor so that it is always at a predetermined point, an aerobic region and an anaerobic region are appropriately formed in the ditch.To do.
[0021]
Claim3, 5The control device of the oxidation ditch water treatment device according to the above measures the factors affecting the microbial activity such as the activated sludge microbial concentration in the ditch, or the water temperature, pH, etc., and uses these measured values within a specific section in the ditch. By correcting the control target value of the dissolved oxygen concentration, an aerobic region and an anaerobic region are always appropriately formed in the ditch.
[0022]
Claim4, 6The control device of the oxidation ditch water treatment apparatus according to the present invention measures the factors affecting the microbial activity such as the activated sludge microbial concentration or water temperature and pH in the ditch, and the dissolved oxygen concentration is determined in advance using this measured value. By correcting the control target value at the point that becomes the reference value, an aerobic region and an anaerobic region are always appropriately formed in the ditch.
[0023]
The control apparatus for the oxidation ditch water treatment apparatus according to claim 7 and 8 measures the quality of the treated water, and changes the target value of the activated sludge microorganism concentration or the target value of the sludge extraction amount so that the measured value becomes constant. Thus, the aerobic region and the anaerobic region are appropriately formed in the ditch, and at the same time, the amount of microorganisms for water treatment is not excessive or insufficient.
[0024]
Claim9The oxidation ditch water treatment device control apparatus according to the present invention measures the inflow load into the ditch and corrects the control reference value of the rotation speed or immersion depth of the aeration rotor by using this measured value. Appropriate formation of aerobic and anaerobic areasTo do.
[0025]
【Example】
For many years, the inventors have repeatedly studied computer simulations based on dynamic models for operation control methods for efficiently removing nitrogen and performing stable advanced treatment in the oxidative ditch water treatment process. It was. As a result, several laws useful for performing the control were discovered and the present invention was reached. First, the dynamic model used for the computer simulation will be described below.
[0026]
A kinetic model of the organic substance removal reaction is represented by Equation 1. This is configured based on the Stenstrom model described in the literature ("Real-Time Control of Activated Sludge Process" (ASCE (EE), 1979)).
[0027]
[Expression 1]

[0028]
here,
r_XS, R_XA, R_XI: Production rate [mg / L · h]
Y₁, Y₂:yield
K_S : Half-saturation constant [mg / L]
K_fS: Half-saturation constant
XT: MLSS (activated sludge microorganism) concentration [mg / L]
XS: MLSAccumulated partial concentration of S [mg / L]
XA: MLSActive part concentration of S [mg / L]
XI: MLSInactive partial concentration of S [mg / L]
fs: XS / XT
fs^M: Maximum value of fs
S: Organic substance concentration [mg / L]
R_T : Movement coefficient [h^-1]
R_XA: Maximum specific growth rate [h^-1]
R_XI: Maximum specific death rate [h^-1]
It is. However, L represents a liter.
[0029]
Further, a kinetic model of nitrification reaction is expressed by Equation 2. This is also based on the Stenstrom model described in the above document.
[0030]
[Expression 2]

[0031]
here,
r_XNS, R_XNB: Production rate [mg / L · h]
r_SNO3, R_SNO2, R_SNH4: Substrate production rate by nitrification reaction [mg / L · h]
XNS: Nitrosomonas concentration [mg / L]
XNB: Nitrobacter concentration [mg / L]
DO: dissolved oxygen concentration [mg / L]
μ_NS(DO), μ_NB(DO): Specific growth rate function by mono (h) [h^-1]
μ_NS ^M, Μ_NB ^M: Maximum specific growth rate [h^-1]
D_XNS, D_XNB: Specific death rate [h^-1]
r_HNH4: Substrate production rate by organic substance removal reaction [mg / L · h]
K_DO: Half-saturation constant [mg / L]
It is.
[0032]
Further, the kinetic model of the denitrification reaction is expressed by Equation 3. This was prepared from data described in “Water Treatment Engineering” (Gihodo Publishing, 1976) and literature (“Biological Densification” (Dep. Of Sanitary Engineering Technical. Of Denmark, 1972)).
[0033]
r_DNO3=-(R_HN+ R_SN) XA
r_DNH4= (0.25R_SN+ 0.02R_HNY_Three) XA
r_DXS= -2.21R_HNXA
r_DXA= (R_HNY_Three-2.0R_SN) XA (3)
[0034]
here,
r_DNO3, R_DNH4, R_DXS, R_DXA: Formation rate by denitrification reaction [mg / L · h]
R_HN: Biosynthetic denitrification rate constant [h^-1]
R_SN: Endogenous denitrification rate constant [h^-1]
Y_Three:yield
It is.
[0035]
Further, the balance of dissolved oxygen concentration is expressed by Equation 4.
[0036]
[Equation 3]

[0037]
here,
r_HDO: Oxygen consumption rate by removing organic substances [mg / L · h]
r_NDO: Oxygen consumption rate by nitrification [mg / L · h]
r_DO : Oxygen transfer rate [mg / L · h]
Y_NS, Y_NB:yield
K_La: Overall oxygen transfer capacity coefficient [h^-1]
DO_s : Saturated dissolved oxygen concentration [mg / L]
It is.
[0038]
The kinetic parameters were set as shown in Table 1.
[0039]
[Table 1]

[0040]
Further, the mixing in the ditch was approximated by a tank row model in the flow direction taking into consideration the circulating flow as shown in FIG. 1, and the mass balance between the tanks was taken.
[0041]
The apparatus conditions were set as shown in Table 2 with reference to "Development of mechanical aeration apparatus used for oxidation ditch method (Ministry of Construction Technical Evaluation No. 82402)".
[0042]
[Table 2]

[0043]
The characteristics of the aeration rotor were set as shown in Equation 5.
[0044]
[Expression 4]

[0045]
here,
OC: Oxygen supply speed per [m] rotor [kg-O₂/ M · h]
NN: Oxygen supply efficiency (shaft power) [kg-O₂/ KWh]
K_La: Overall oxygen transfer capacity coefficient [h^-1]
q: Power consumption [kW]
V_m : Average velocity in pond [m / s]
L: Channel length [m]
φ: Ratio of input power used for propulsion
P_r : Power input density [W / m^Three]
V_u : Rotor peripheral speed [m / s]
ζ: Channel loss coefficient
[0046]
2, 3, and 4, the MLSS concentration is set to 3000 [mg / L], and the aeration rotor immersion depth is changed to 15 [cm], 20 [cm], and 24 [cm], respectively. In (a), (b), and (c) in the figure, the dissolved oxygen concentration distribution in the ditch when the above simulation is performed while changing the rotational speed of the aeration rotor to 48 [rpm], 60 [rpm], and 71 [rpm]. It is a figure which shows the relationship between the total nitrogen concentration of process water. The horizontal axis shows the point where the ditch is divided into 6 equal parts in the flow direction, and as shown in FIG. Named. The vertical axis represents the dissolved oxygen concentration. The number on the right shoulder in the graph indicates the total nitrogen concentration at point F, the left side in parentheses indicates the ammonia nitrogen concentration, and the right side indicates the nitrate nitrogen concentration.
[0047]
Similarly, FIG. 5, FIG. 6, and FIG. 7 are diagrams showing the results when simulation was performed with the MLSS concentration set to 4000 [mg / L], and FIGS. 8, 9, and 10 show the MLSS concentration. It is a figure which shows the relationship between the dissolved oxygen concentration distribution in a ditch, and the total nitrogen concentration of treated water when it simulates by setting to 5000 [mg / L].
[0048]
From these figures, it can be seen that when the total nitrogen concentration in the treated water is low, nitrate nitrogen and ammonia nitrogen remain to the same extent. To help understanding, FIG. 11 shows a graph in which the horizontal axis represents the difference between the nitrate nitrogen concentration and the ammonia nitrogen concentration at the point F, and the vertical axis represents the sum of both, that is, the total nitrogen concentration. The difference between nitrate nitrogen concentration and ammonia nitrogen concentration when the MLSS concentration is 3000 [mg / L] (solid line), 4000 [mg / L] (dotted line), and 5000 [mg / L] (dashed line) When is 0, the total nitrogen concentration is minimal. From this, the inventors have said that "if the nitrate nitrogen concentration and ammonia nitrogen concentration in the treated water remain approximately the same, the total nitrogen concentration in the treated water can be minimized." I found the law.
[0049]
FIG. 11 also shows that the higher the MLSS concentration, the smaller the total nitrogen concentration in the treated water. From this, the inventors have found the second law that “in order to further remove nitrogen, it is necessary to keep the MLSS concentration high”.
[0050]
If the first and second laws are applied to the operation of an actual oxidation ditch water treatment process, it is possible to achieve advanced treatment of nitrogen in sewage. The inventors further examined the previous FIGS. 2 to 10 more carefully in order to find a simpler method that does not require measurement or analysis of nitrogen concentration. According to these figures, regardless of the MLSS concentration, when the dissolved oxygen concentration disappears in the vicinity of the points C to D, that is, the aerobic region and the anaerobic region are formed approximately equally and nitrification / denitrification occurs in a balanced manner. It can be seen that the total nitrogen concentration in the treated water is low.
It can be said that the optimum point of the boundary between the aerobic region and the anaerobic region depends on the ratio between the nitrification rate and the denitrification rate. To help understanding, when the nitrification rate is set to 10 times the normal value (μ in Table 1)_NS ^M, Μ_NB ^MThe simulation results are shown in FIGS. 12, 13, and 14 when the denitrification rate is set to 10 times the normal value (R in Table 1)._HN, R_SN15, 16, and 17 show the simulation results. The way of viewing the figure is the same as in FIGS.
[0051]
In FIGS. 12, 13, and 14, when the dissolved oxygen concentration disappears near the point B, the total nitrogen concentration in the treated water is low. This is because the aerobic region may be shorter if the nitrification rate is higher than the denitrification rate, so the optimum end point of the aerobic region for the treated water quality is forward from the center of the ditch to the front (aeration rotor side). It is shifted. On the other hand, in FIGS. 15, 16, and 17, when the dissolved oxygen concentration disappears near the point E, the total nitrogen concentration in the treated water is low. This is because if the denitrification rate is larger than the nitrification rate, the anaerobic region may be short, and the optimum end position of the aerobic region with respect to the treated water quality is shifted backward from the vicinity of the center of the ditch.
[0052]
The conditions of this simulation are set regardless of the actual phenomenon in order to help understanding, and the nitrification rate and the denitrification rate cannot actually deviate greatly from the literature values. However, the water temperature, pH, oxidation-reduction potential, etc. have some influence on the nitrification rate and denitrification rate, and the degree of the effect differs between the nitrification rate and the denitrification rate. From this, the inventors have stated that “the boundary between the aerobic region and the anaerobic region optimal for nitrogen removal is usually near the center of the ditch. However, the location is microbial activity such as water temperature, pH, redox potential The third law was found to be "affected by fluctuations in factors that affect it."
[0053]
Finally, with respect to the dissolved oxygen concentration distribution in the ditch, it can be seen from FIGS. 2 to 10 that the gradient of the dissolved oxygen concentration distribution is different when the MLSS concentration is different even if the rotation speed of the aeration rotor and the immersion depth are the same. To help understanding, FIG. 18 shows a graph in which the horizontal axis represents the dissolved oxygen concentration at point A and the vertical axis represents the total nitrogen concentration at point F. From this figure, it can be seen that the higher the MLSS concentration, the higher the dissolved oxygen concentration at the point A where the total nitrogen concentration is minimized. As described when deriving the third law, when the total nitrogen concentration in the treated water was low, the dissolved oxygen concentration disappeared in the vicinity of the points C to D when the MLSS concentration was any. That is, the higher the MLSS concentration, the more rapidly the dissolved oxygen concentration distribution is formed. From this, the inventors found the fourth law that "the higher the MLSS concentration, the steeper the dissolved oxygen concentration distribution".
[0054]
Reference Example 1
Hereinafter, the present inventionReference examples related toWill be described with reference to FIG. FIG.Reference example 1It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. 19, the same reference numerals as those in FIG. 43 denote the same or corresponding parts. Reference numeral 100 denotes a nitrate nitrogen concentration meter attached to a pipe c for discharging the precipitated treated water, and 101 denotes an ammonia nitrogen concentration meter. Reference numeral 102 denotes a controller that outputs a target value of the rotational speed of the aeration rotor 2 in accordance with a deviation between a difference between the nitrate nitrogen concentration and the ammonia nitrogen concentration and a target value of a predetermined concentration difference. The nitrate nitrogen concentration meter 100 is connected to 100a, the ammonia nitrogen concentration meter 101 is connected to the signal line 101a, and the driving device 3 is connected to the signal line 102a. Reference numeral 103 denotes a setter for setting a target value of the density difference, which is connected to the controller 102 through a signal line 103a. The target value set in the setting device 103 is more effective when it is in the range of -10 to 10 [mg-N / L], desirably in the vicinity of 0 [mg-N / L] based on the first law. Note that [mg-N / L] represents a unit representing the concentration of nitrogen N.
[0055]
Next, the operation will be described. The nitrate nitrogen concentration in the treated water is measured with a nitrate nitrogen concentration meter 100, and the ammonia nitrogen concentration is measured with an ammonia nitrogen concentration meter 101. Each measured value is transmitted to the controller 102 via the signal lines 100a and 101a. The controller 102 outputs a target value of the rotational speed of the aeration rotor 2 according to, for example, Equation 6 according to the deviation between the difference between the nitrate nitrogen concentration and the ammonia nitrogen concentration and the target value of the predetermined concentration difference. .
[0056]
R_rot= R_rot0+ K_RDN(DN^*-DN) (6)
here,
R_rot : Target value of the rotation speed of the aeration rotor
R_rot0:constant
K_RDN :constant
DN^* : (Nitrate nitrogen concentration-ammonia nitrogen concentration) target value
DN: nitrate nitrogen concentration-ammonia nitrogen concentration
It is.
Target value DN of density difference necessary for this calculation^* Is obtained as an output of the setting device 103 via the signal line 103a. Output R of controller 102_rot Is transmitted to the driving device 3 via the signal line 102a, and the rotational speed of the aeration rotor 2 is adjusted.
[0057]
As a result, the density difference DN becomes the target value DN.^* If it is smaller than that, the rotation speed of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the density difference DN is the target value DN.^* If it is larger than that, the rotational speed of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, if the rotation speed of the aeration rotor 2 is automatically adjusted so that the nitrate nitrogen concentration and the ammonia nitrogen concentration remain in the treated water even if the inflow load to the ditch 1 fluctuates, it is aerobic. It can be adjusted so that the end of the region is near the center of the ditch, and good treated water quality can be maintained stably.
[0058]
Reference Example 2
The present inventionOther reference examples related toWill be described with reference to FIG. FIG.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on 2. FIG. In FIG. 20, reference numeral 104 denotes a controller that outputs a target value of the immersion depth of the aeration rotor 2 in accordance with a deviation between a difference between the nitrate nitrogen concentration and the ammonia nitrogen concentration and a target value of a predetermined concentration difference. The signal line 100a is connected to the nitrate nitrogen concentration meter 100, the signal line 101a is connected to the ammonia nitrogen concentration meter 101, and the signal line 103a is connected to the setting unit 103 for setting the target value of the concentration difference.Reference exampleAs in the case of 1, the target value set in the setting device 103 is more effective when it is in the range of −10 to 10 [mg-N / L], desirably in the vicinity of 0 [mg-N / L]. An arithmetic unit 12 calculates a target value of the height of the overflow basin 4 from a target value of the immersion depth of the aeration rotor 2, and is connected to the controller 104 by a signal line 104a. Reference numeral 13 denotes a driving device for changing the height of the overflow basin 4, which is connected to the overflow basin 4 by the driving force transmission means 13a and to the calculator 12 by the signal line 12a. Others are the same as FIG.
[0059]
Next, the operation will be described. The controller 104 outputs the target value of the immersion depth of the aeration rotor 2 according to, for example, Equation 7, according to the deviation between the difference between the nitrate nitrogen concentration and the ammonia nitrogen concentration and the target value of the predetermined concentration difference. To do.
D_rot= D_rot0+ K_DDN(DN^*-DN) (7)
here,
D_rot ： Target value of immersion depth of aeration rotor
D_rot0:constant
K_DDN :constant
It is.
The measured value of the nitrate nitrogen concentration required for this calculation is output as the output of the nitrate nitrogen concentration meter 100 via the signal line 100a, and the measured value of the ammonia nitrogen concentration is output as the output of the ammonia nitrogen concentration meter 101 as the signal line 101a. Obtained through. Target value DN of density difference^* Is obtained as an output of the setting device 103 via the signal line 103a. Output D of controller 104_rot Is transmitted to the arithmetic unit 12 through the signal line 104a.
In the calculator 12, the target value D of the immersion depth of the aeration rotor 2_rot The target value of the height of the overflow overflow 4 is calculated according to, for example, Equation 8.
H = H₀+ D_rot                                       ... (8)
here,
H: Target value for the height of the overflow cough
H₀:constant
It is.
The output H of the arithmetic unit 12 is transmitted to the driving device 13 via the signal line 12a, and the immersion depth of the aeration rotor 2 is adjusted.
[0060]
As a result, the density difference DN becomes the target value DN.^* If it is smaller than this, the immersion depth of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the density difference DN is the target value DN.^* If it is larger, the immersion depth of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, even if the inflow load to the ditch 1 fluctuates, the immersion depth of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch, so that a good treated water quality is stably maintained. Will be able to.
[0061]
In FIG. 20, the target value D of the immersion depth, which is the output of the controller 104._rot Is calculated by the calculator 12 to the target value H of the height of the overflow basin 4, but the calculation of the equations 7 and 8 is performed by the controller 104 at a time and the calculator 12 is omitted. The effect of.
[0062]
Reference Example 3.
the aboveReference exampleIn 1 and 2, the ammonia nitrogen concentration was subtracted from the nitrate nitrogen concentration, but the same effect can be obtained even if the nitrate nitrogen concentration is subtracted from the ammonia nitrogen concentration.
[0063]
Reference Example 4
The present inventionOther reference examples related toWill be described with reference to FIG. FIG.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on 4. FIG. In FIG. 21, reference numeral 105 denotes an adjustment for outputting a target value of the rotational speed of the aeration rotor 2 in accordance with a deviation between a concentration ratio of nitrate nitrogen concentration and ammonia nitrogen concentration and a target value of a predetermined concentration ratio. The nitrate nitrogen concentration meter 100 is connected to the signal line 100a, the ammonia nitrogen concentration meter 101 is connected to the signal line 101a, and the driving device 3 is connected to the signal line 105a. Reference numeral 106 denotes a setter for setting a target value of the concentration ratio, which is connected to the controller 105 through a signal line 106a. The target value set in the setting device 106 is more effective if it is in the range of 0.1 to 10, preferably in the vicinity of 1, from the first law. Others are the same as FIG.
[0064]
Next, the operation will be described. In the controller 105, the target value of the rotational speed of the aeration rotor 2 is determined according to, for example, Equation 9 according to the deviation between the concentration ratio between the nitrate nitrogen concentration and the ammonia nitrogen concentration and the target value of the predetermined concentration ratio. Output.
R_rot= R_rot0+ K_RRN1(RN₁ ^*-RN₁(9)
here,
K_RRN1:constant
RN₁ ^*: (Nitrate nitrogen concentration / ammonia nitrogen concentration) target value
RN₁ : Nitrate nitrogen concentration / ammonia nitrogen concentration
It is.
The measured value of the nitrate nitrogen concentration required for this calculation is output as the output of the nitrate nitrogen concentration meter 100 via the signal line 100a, and the measured value of the ammonia nitrogen concentration is output as the output of the ammonia nitrogen concentration meter 101 as the signal line 101a. Obtained through. Target value RN of concentration ratio₁ ^*Is obtained as an output of the setting device 106 via the signal line 106. Output R of controller 105_rot Is transmitted to the driving device 3 via the signal line 105a, and the rotational speed of the aeration rotor 2 is adjusted.
[0065]
Thereby, the concentration ratio RN₁ Is the target value RN₁ ^*If it is smaller than that, the rotation speed of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the concentration ratio RN₁ Is the target value RN₁ ^*If it is larger than that, the rotational speed of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, even if the inflow load to the ditch 1 fluctuates, the rotation speed of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch, so that good treated water quality can be kept stable. Will be able to.
[0066]
Reference Example 5
The present inventionOther reference examples related toWill be described with reference to FIG. FIG.Reference example5 is a configuration diagram showing a control device of an oxidation ditch water treatment device according to FIG. In FIG. 22, reference numeral 107 denotes a controller that outputs a target value of the immersion depth of the aeration rotor 2 in accordance with a deviation between a ratio between the nitrate nitrogen concentration and the ammonia nitrogen concentration and a target value of a predetermined concentration ratio. The signal line 100a is connected to the nitrate nitrogen concentration meter 100, the signal line 101a is connected to the ammonia nitrogen concentration meter 101, and the signal line 106a is connected to the setting device 106 for setting the target value of the concentration difference.Reference exampleAs in the case of 4, the target value set in the setting device 106 is more effective when it is in the range of 0.1 to 10, preferably in the vicinity of 1. The controller 107 is also connected to a calculator 12 that calculates the target value of the height of the overflow basin 4 from the target value of the immersion depth of the aeration rotor 2 through the signal line 107a. Others are the same as FIG.
[0067]
Next, the operation will be described. In the controller 107, the target value of the immersion depth of the aeration rotor 2 is set according to, for example, the equation 10 according to the deviation between the concentration ratio between the nitrate nitrogen concentration and the ammonia nitrogen concentration and the target value of the predetermined concentration ratio. According to the output.
D_rot= D_rot0+ K_DRN1(RN₁ ^*-RN₁(10)
here,
K_DRN1:constant
It is.
The measured value of the nitrate nitrogen concentration required for this calculation is output as the output of the nitrate nitrogen concentration meter 100 via the signal line 100a, and the measured value of the ammonia nitrogen concentration is output as the output of the ammonia nitrogen concentration meter 101 as the signal line 101a. Obtained through. Target value RN of concentration ratio₁ ^*Is obtained via the signal line 106 a as an output of the setting device 106. Output D of controller 107_rot Is transmitted to the arithmetic unit 12 via the signal line 107a. Less than,Reference exampleSimilarly to 2, the height of the overflow dam 4 is adjusted to adjust the immersion depth of the aeration rotor 2.
[0068]
Thereby, the concentration ratio RN₁ Is the target value RN₁ ^*If it is smaller than this, the immersion depth of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the concentration ratio RN₁ Is the target value RN₁ ^*If it is larger, the immersion depth of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, even if the inflow load to the ditch 1 fluctuates, the immersion depth of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch, so that a good treated water quality is stably maintained. Will be able to.
[0069]
Although FIG. 22 shows an example in which the target value of the immersion depth, which is the output of the controller 107, is calculated by the calculator 12 to the target value of the height of the overflow basin 4, the calculation is performed by the controller 107 at a time. Even if the arithmetic unit 12 is omitted, the same effect can be obtained.
[0070]
Reference Example 6
the aboveReference exampleIn Nos. 4 and 5, the nitrate nitrogen concentration was divided by the ammonia nitrogen concentration, but the same effect can be obtained by dividing the ammonia nitrogen concentration by the nitrate nitrogen concentration.
[0071]
Reference Example 7
The present inventionOther reference examples related toWill be described with reference to FIG. FIG.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on FIG. In FIG. 23, 25 is a total nitrogen concentration meter attached to the piping c for discharging the sedimentation treated water. Reference numeral 108 denotes a controller that outputs a target value of the rotational speed of the aeration rotor 2 in accordance with a deviation between the concentration ratio of nitrate nitrogen concentration to the total nitrogen concentration and a predetermined target value of the concentration ratio. The total nitrogen concentration meter 25 is connected to the line 25a, the nitrate nitrogen concentration meter 100 is connected to the signal line 100a, and the driving device 3 is connected to the signal line 108a. Reference numeral 109 denotes a setter for setting a target value of the concentration ratio, which is connected to the controller 108 through a signal line 109a. The target value set in the setter 109 is the total nitrogen concentration obtained by adding the nitrate nitrogen concentration and the ammonia nitrogen concentration, and as shown in the first law, the nitrate nitrogen concentration and the ammonia nitrogen are set. Since the total nitrogen concentration in the treated water can be minimized when the concentrations are almost equal, the ratio between the nitrate nitrogen concentration and the total nitrogen concentration is in the range of 1:10 to 9:10, and the optimum ratio is 1 : Set to 2 That is, it is effective that the concentration ratio of nitrate nitrogen concentration to total nitrogen concentration is in the range of 0.1 to 0.9, preferably 0.25 to 0.75, and the optimum value is around 0.5. . Others are the same as FIG.
[0072]
Next, the operation will be described. The controller 108 outputs a target value of the rotational speed of the aeration rotor 2 according to, for example, Equation 11 according to a deviation between a concentration ratio of nitrate nitrogen concentration and total nitrogen concentration and a target value of a predetermined concentration ratio. To do.
R_rot= R_rot0+ K_RRN2(RN₂ ^*-RN₂(11)
here,
K_RRN2:constant
RN₂ ^*: (Nitrate nitrogen concentration / total nitrogen concentration) target value
RN₂ : Nitrate nitrogen concentration / total nitrogen concentration
It is.
The measured value of the nitrate nitrogen concentration necessary for this calculation is output as the output of the nitrate nitrogen concentration meter 100 via the signal line 100a, and the measured value of the total nitrogen concentration is output as the output of the total nitrogen concentration meter 25 via the signal line 25a. Obtained. Target value RN of concentration ratio₂ ^*Is obtained as an output of the setting device 109 via the signal line 109. Output R of controller 108_rot Is transmitted to the driving device 3 through the signal line 108a, and the rotational speed of the aeration rotor 2 is adjusted.
[0073]
Thereby, the concentration ratio RN₂ Is the target value RN₂ ^*If it is smaller than that, the rotation speed of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the concentration ratio RN₂ Is the target value RN₂ ^*If it is larger than that, the rotational speed of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, even if the inflow load to the ditch 1 fluctuates, the rotation speed of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch, so that good treated water quality can be kept stable. Will be able to.
[0074]
Reference Example 8
The present inventionOther reference examples related toWill be described with reference to FIG. FIG.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on FIG. In FIG. 24, reference numeral 110 denotes a controller that outputs a target value of the immersion depth of the aeration rotor 2 in accordance with a deviation between the concentration ratio of nitrate nitrogen concentration to the total nitrogen concentration and a target value of a predetermined concentration ratio. Yes, the signal line 25a is connected to the total nitrogen concentration meter 25, the signal line 100a is connected to the nitrate nitrogen concentration meter 100, and the signal line 109a is connected to the setting device 109 for setting the target value of the concentration difference.Reference exampleAs in FIG. 7, the target value set in the setting device 109 is effectively in the range of 0.1 to 0.9, desirably 0.25 to 0.75, and the optimum value is close to 0.5. The controller 110 is also connected to a calculator 12 that calculates a target value of the height of the overflow basin 4 from a target value of the immersion depth of the aeration rotor 2. Others are the same as FIG.
[0075]
Next, the operation will be described. In the controller 110, the target value of the immersion depth of the aeration rotor 2 is determined according to, for example, Equation 12 according to the deviation between the concentration ratio between the nitrate nitrogen concentration and the total nitrogen concentration and the target value of the predetermined concentration ratio. Output.
D_rot= D_rot0+ K_DRN2(RN₂ ^*-RN₂(12)
here,
K_DRN2:constant
It is.
The measured value of the total nitrogen concentration necessary for this calculation is output as the output of the total nitrogen concentration meter 25 via the signal line 25a, and the measured value of the nitrate nitrogen concentration is output as the output of the nitrate nitrogen concentration meter 100 via the signal line 100a. Obtained. Target value RN of concentration ratio₂ ^*Is obtained as an output of the setting device 109 via a signal line 109a. Output D of controller 110_rot Is transmitted to the arithmetic unit 12 via the signal line 110a.
[0076]
Thereby, the concentration ratio RN₂ Is the target value RN₂ ^*If it is smaller than this, the immersion depth of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the concentration ratio RN₂ Is the target value RN₂ ^*If it is larger, the immersion depth of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, even if the inflow load to the ditch 1 fluctuates, the immersion depth of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch, so that a good treated water quality is stably maintained. There is an effect that can be.
[0077]
In FIG. 24, the target value D of the immersion depth, which is the output of the controller 110._rot Although the calculation unit 12 calculates the target value at the height of the overflow basin 4, the calculation is performed by the controller 110 at the same time, and the same effect can be obtained even if the calculation unit 12 is omitted.
[0078]
Reference Example 9
the aboveReference exampleIn Nos. 7 and 8, the nitrate nitrogen concentration was divided by the total nitrogen concentration, but the same effect can be obtained by dividing the total nitrogen concentration by the nitrate nitrogen concentration. However, it is effective that the target value of the concentration ratio at this time is in the range of 1 to 10, desirably 1.3 to 4.0, and the optimum value is close to 2.
[0079]
Reference Example 10
The present inventionOther reference examples related toWill be described with reference to FIG. FIG.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on FIG. In FIG. 25, reference numeral 111 denotes a controller that outputs a target value of the rotational speed of the aeration rotor 2 in accordance with a deviation between a concentration ratio of the ammonia nitrogen concentration to the total nitrogen concentration and a target value of a predetermined concentration ratio. The total nitrogen concentration meter 25 is connected to the signal line 25a, the ammonia nitrogen concentration meter 101 is connected to the signal line 101a, and the driving device 3 is connected to the signal line 111a. Reference numeral 112 denotes a setter for setting a target value of the concentration ratio, which is connected to the controller 111 through a signal line 112a. The target value set in the setting device 112 isReference exampleAs described in Section 7, the total nitrogen concentration is the sum of the nitrate nitrogen concentration and the ammonia nitrogen concentration. As shown in the first law, the nitrate nitrogen concentration and the ammonia nitrogen concentration are almost equal. Since the total nitrogen concentration in the treated water can be minimized when equal, the ratio of the ammoniacal nitrogen concentration to the total nitrogen concentration is in the range of 1:10 to 9:10, and the optimal ratio is 1: 2. It is good to set as follows. That is, the concentration ratio of the ammonia nitrogen concentration to the total nitrogen concentration is in the range of 0.1 to 0.9, preferably 0.25 to 0.75, and the optimum value is close to 0.5. . Others are the same as FIG.
[0080]
Next, the operation will be described. The controller 111 outputs a target value of the rotational speed of the aeration rotor 2 according to, for example, Equation 13, according to a deviation between the concentration ratio between the ammonia nitrogen concentration and the total nitrogen concentration and the target value of the predetermined concentration ratio. To do.
R_rot= R_rot0-K_RRN3(RN_Three ^*-RN_Three(13)
here,
K_RRN3:constant
RN_Three ^*: Target value of (ammonia nitrogen concentration / total nitrogen concentration)
RN_Three : Ammonia nitrogen concentration / total nitrogen concentration
It is.
The measured value of ammonia nitrogen concentration required for this calculation is output as the output of the ammonia nitrogen concentration meter 101 via the signal line 101a, and the measured value of the total nitrogen concentration is determined as the output of the total nitrogen concentration meter 25 via the signal line 25a. can get. Target value RN of concentration ratio_Three ^*Is obtained as an output of the setting device 112 via the signal line 112. Output R of controller 111_rot Is transmitted to the driving device 3 via the signal line 111a, and the rotational speed of the aeration rotor 2 is adjusted.
[0081]
Thereby, the concentration ratio RN_Three Is the target value RN_Three ^*If it is larger, the number of rotations of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the concentration ratio RN_Three Is the target value RN_Three ^*If it is smaller than that, the rotational speed of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, even if the inflow load to the ditch 1 fluctuates, the rotation speed of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch, so that good treated water quality can be kept stable. Will be able to.
[0082]
Reference Example 11
The present inventionOther reference examples related toWill be described with reference to FIG. FIG.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on FIG. In FIG. 26, reference numeral 113 denotes a controller that outputs a target value of the immersion depth of the aeration rotor 2 in accordance with a deviation between the concentration ratio of the ammoniacal nitrogen concentration with respect to the total nitrogen concentration and a predetermined target value of the concentration ratio. Yes, the signal line 25a is connected to the total nitrogen concentration meter 25, the signal line 101a is connected to the ammonia nitrogen concentration meter 101, and the signal line 112a is connected to the setting device 112 for setting the target value of the concentration difference. The controller 113 is also connected to a calculator 12 that calculates a target value for the height of the overflow basin 4 from a target value for the immersion depth of the aeration rotor 2. Others are the same as FIG.
[0083]
Next, the operation will be described. In the controller 113, the target value of the immersion depth of the aeration rotor 2 is determined according to, for example, Equation 14 according to the deviation between the concentration ratio between the ammonia nitrogen concentration and the total nitrogen concentration and the target value of the predetermined concentration ratio. Output.
D_rot= D_rot0-K_DRN3(RN_Three ^*-RN_Three(14)
here,
K_DRN3:constant
It is.
The measured value of the total nitrogen concentration necessary for this calculation is obtained as the output of the total nitrogen concentration meter 25, and the measured value of the ammonia nitrogen concentration is obtained as the output of the ammonia nitrogen concentration meter 25 via the signal line 25a. Target value RN of concentration ratio_Three ^*Is obtained as an output of the setting device 112 via the signal line 112a. Output D of controller 113_rot Is transmitted to the arithmetic unit 12 through the signal line 113a.
[0084]
Thereby, the concentration ratio RN_Three Is the target value RN_Three ^*Is larger, the immersion depth of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the concentration ratio RN_Three Is the target value RN_Three ^*If smaller than this, the immersion depth of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, even if the inflow load to the ditch 1 fluctuates, the immersion depth of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch, so that a good treated water quality is stably maintained. Will be able to.
[0085]
26 shows an example in which the target value of the immersion depth, which is the output of the controller 113, is calculated by the calculator 12 to the target value of the height of the overflow basin 4, but the calculation is performed by the controller 113 at once. Even if the arithmetic unit 12 is omitted, the same effect can be obtained.
[0086]
Reference Example 12.
the aboveReference example10 and 11, the ammonia nitrogen concentration was divided by the total nitrogen concentration, but the same effect can be obtained by dividing the total nitrogen concentration by the ammonia nitrogen concentration. However, the target value of the concentration ratio at this time isReference exampleSimilarly to 9, it is effective to set the range of 1 to 10, preferably 1.3 to 4.0, and the optimum value in the vicinity of 2.
[0087]
Example1.
Claims of the invention1An embodiment according to the present invention will be described with reference to the drawings. FIG. 27 shows an example.1It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 27, 8 is a dissolved oxygen concentration meter, which is near the center of the ditch 1 starting from the installation point of the aeration rotor 2, preferably 1/4 to 1/1 of the ditch length in the flow direction from the installation point of the aeration rotor 2. Measure the dissolved oxygen concentration at a point 2 times away. As indicated by the third law, since the boundary between the aerobic region and the anaerobic region that is optimal for nitrogen removal is near the center of the ditch, it is dissolved at the center of the ditch 1 or slightly in front (the aeration rotor 2 side). By measuring the oxygen concentration, it can be reliably detected that the end of the aerobic region comes near the center of the ditch 1. When the dissolved oxygen concentration near the aeration rotor 2 is measured, it is difficult to estimate the end position of the aerobic region in the oxidation ditch where the fluctuation of the inflow load is large and the distribution of the dissolved oxygen concentration is unstable. Since it is not possible to detect that the aerobic region is too short behind the center of 1, the dissolved oxygen concentration at a point away from the aeration rotor 2 installation point by 1/4 to 1/2 times the ditch length in the flow direction is measured. Is most appropriate.
[0088]
Reference numeral 9 denotes a controller that outputs a target value of the rotational speed of the aeration rotor 2 in accordance with a deviation between a measured value of the dissolved oxygen concentration and a predetermined target value of the dissolved oxygen concentration. A total of 8 is connected to the driving device 3 through a signal line 9a. Reference numeral 10 denotes a setter for setting a target value of the dissolved oxygen concentration, which is connected to the controller 9 through a signal line 10a. Since the target value set in the setting device 10 is the dissolved oxygen concentration slightly ahead of the end of the aerobic region, it is set to a value in the vicinity of 0 [mg / L], preferably 0 to 1 [mg / L]. Is appropriate. Others are the same as FIG.
[0089]
Next, the operation will be described. The dissolved oxygen concentration at a point away from the aeration rotor 2 installation point by ¼ to ½ times the ditch length in the flow direction is measured by the dissolved oxygen concentration meter 8. The measured value of the dissolved oxygen concentration is transmitted to the controller 9 via the signal line 8a. The controller 9 outputs the target value of the rotational speed of the aeration rotor 2 according to, for example, Expression 15 according to the deviation between the measured value of the dissolved oxygen concentration and the predetermined target value of the dissolved oxygen concentration.
R_rot= R_rot0+ K_RDO(DO^*-DO) (15)
here,
K_RDO :constant
DO^* : Target value of dissolved oxygen concentration
DO: Measurement value of dissolved oxygen concentration
It is.
Target value DO of dissolved oxygen concentration required for this calculation^* Is obtained as an output of the setting device 10 via the signal line 10a. Output R of controller 9_rot Is transmitted to the driving device 3 via the signal line 9a, and the rotational speed of the aeration rotor 2 is adjusted.
[0090]
As a result, the measured value DO of the dissolved oxygen concentration becomes the target value DO.^* If it is smaller than that, the rotation speed of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the measured value DO of the dissolved oxygen concentration is the target value DO.^* If it is larger than that, the rotational speed of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, even if the inflow load to the ditch 1 fluctuates, the rotation speed of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch, so that measurement and analysis of the nitrogen concentration is not performed. In addition, there is an effect that the quality of the treated water can be stably maintained.
[0091]
Example2.
Claims of the invention1Another embodiment according to the present invention will be described with reference to the drawings. FIG. 28 shows an example.2It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 28, 11 is a measured value of the dissolved oxygen concentration at a point separated by ¼ to ½ times the ditch length in the flow direction from the installation position of the aeration rotor 2, and is set in the vicinity of 0 [mg / L] in advance. Is a controller that outputs the target value of the immersion depth of the aeration rotor 2 in accordance with the deviation from the target value of the dissolved oxygen concentration, and the dissolved oxygen concentration is measured by the signal line 8a and the signal line 10a. It is connected to a setting device 10 for setting a target value. An arithmetic unit 12 calculates a target value of the height of the overflow basin 4 from a target value of the immersion depth of the aeration rotor 2, and is connected to the controller 11 by a signal line 11a. Reference numeral 13 denotes a driving device for changing the height of the overflow basin 4, which is connected to the overflow basin 4 by the driving force transmission means 13a and to the calculator 12 by the signal line 12a. Others are the same as FIG.
[0092]
Next, the operation will be described. The controller 11 outputs the target value of the immersion depth of the aeration rotor 2 according to, for example, Equation 16 according to the deviation between the measured value of the dissolved oxygen concentration and the predetermined target value of the dissolved oxygen concentration.
D_rot= D_rot0+ K_DDO(DO^*-DO) (16)
here,
K_DDO :constant
It is.
The measured value DO of the dissolved oxygen concentration necessary for this calculation is the output of the dissolved oxygen concentration meter 8 via the signal line 8a and the target value DO of the dissolved oxygen concentration.^* Is obtained as an output of the setting device 10 via the signal line 10a. Output D of controller 11_rotIs transmitted to the arithmetic unit 12 via the signal line 11a.
[0093]
The output of the arithmetic unit 12 is transmitted to the driving device 13 through the signal line 12a, and the rotational speed of the aeration rotor 2 is adjusted.
[0094]
As a result, the measured value DO of the dissolved oxygen concentration becomes the target value DO.^* If it is smaller than this, the immersion depth of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the measured value DO of the dissolved oxygen concentration is the target value DO.^* If it is larger, the immersion depth of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, since the immersion depth of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch even if the inflow load to the ditch 1 fluctuates, measurement and analysis of nitrogen concentration are not performed. In addition, there is an effect that the quality of the treated water can be stably maintained.
[0095]
In FIG. 28, an example in which the target value of the immersion depth, which is the output of the controller 11, is calculated by the calculator 12 to the target value of the height of the overflow basin 4, but the calculation is performed by the controller 11 at once. Even if the arithmetic unit 12 is omitted, the same effect can be obtained.
[0096]
Example3.
Claims of the invention2An embodiment according to the present invention will be described with reference to the drawings. FIG. 29 shows an example.3It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 29, reference numeral 14 denotes an arithmetic unit that calculates a point where the dissolved oxygen concentration in the ditch 1 reaches a predetermined reference value of the dissolved oxygen concentration from the measured value of the dissolved oxygen concentration and the rotation speed of the aeration rotor 2. The dissolved oxygen concentration meter 8 is connected to the aeration rotor 2 through a line 8a, and the aeration rotor 2 is connected through a signal line 2a. The dissolved oxygen concentration meter 8 has a ditch length of 0 to the front from the vicinity of the center of the ditch 1, that is, the range from the installation position of the aeration rotor to the vicinity of the center of the ditch, preferably from the installation position of the aeration rotor 2. Install in the range up to a point that is 1/2 times away. The purpose is to calculate the dissolved oxygen concentration distribution starting from the measurement value of the dissolved oxygen concentration meter 8 and to adjust the rotation speed of the aeration rotor 2 so that the end of the aerobic region is near the center of the ditch 1. That's why. Reference numeral 15 denotes a setter for setting a reference value of the dissolved oxygen concentration, which is connected to the calculator 14 through a signal line 15a. Since the reference value set in the setting device 15 is the dissolved oxygen concentration indicating the end of the aerobic region, it is appropriate to select a value in the vicinity of 0 [mg / L], preferably 0 to 1 [mg / L]. It is. 16 outputs the target value of the rotational speed of the aeration rotor 2 according to the deviation between the calculated value (calculated point) at which the dissolved oxygen concentration in the ditch 1 reaches the reference value and the target value (target point) at that point. The controller is connected to the arithmetic unit 14 through a signal line 14a and the driving device 3 of the aeration rotor 2 through a signal line 16a. Reference numeral 17 denotes a setter for setting a target value at the point, which is connected to the controller 16 through a signal line 17a. The target value set in the setting device 17 is3Since it is better to be near the center of the ditch 1 according to the law of the above, it is appropriate to select from the range from the installation point of the aeration rotor 2 to a point separated by 1/4 to 3/4 times the ditch length in the flow direction . Others are the same as FIG.
[0097]
Next, the operation will be described. In the calculator 14, for example, the distance in the flow direction from the point where the dissolved oxygen concentration meter 8 is installed at the point where the dissolved oxygen concentration in the ditch 1 reaches a predetermined reference value of the dissolved oxygen concentration is calculated according to Equation 17.
x = (DO-DO^**) / R_r× V (R_rot(17)
here,

It is.
The measured value DO of the dissolved oxygen concentration necessary for this calculation is the output of the dissolved oxygen concentration meter 8 via the signal line 8a and the rotational speed R of the aeration rotor 2._rot Is obtained as an output of the aeration rotor 2 through a signal line 2a. Reference value DO of dissolved oxygen concentration^**Is obtained as an output of the setting device 15 via a signal line 15a. The calculation result x is transmitted to the controller 16 via the signal line 14a. It should be noted that the circulation flow velocity V (R_rot) Is the rotational speed R of the aeration rotor 2_rot You may measure directly using an anemometer, without obtaining more.
The controller 16 outputs a target value for the rotational speed of the aeration rotor 2 in accordance with, for example, the deviation between the calculated value x at the point where the dissolved oxygen concentration in the ditch 1 reaches the reference value and the target value at the point according to Equation 18.
R_rot= R_rot0+ K_Rx(X^*-X) (18)
here,
K_Rx:constant
x^* : The target value of the distance in the flow direction from the point where the dissolved oxygen concentration meter 8 is installed at the point where the dissolved oxygen concentration in the ditch 1 reaches a predetermined reference value of the dissolved oxygen concentration.
Target value x at which the dissolved oxygen concentration in Ditch 1 necessary for this calculation reaches the reference value^* Is obtained as an output of the setting device 17 via a signal line 17a. Output R of controller 16_rot Is transmitted to the driving device 3 via the signal line 16a, and the rotational speed of the aeration rotor 2 is adjusted.
[0098]
As a result, the calculated value x at the point where the dissolved oxygen concentration reaches the reference value becomes the target value x.^* If it is smaller than that, the rotation speed of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the calculated value x at the point where the dissolved oxygen concentration reaches the reference value is the target value x.^* If it is larger than that, the rotational speed of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, even if the inflow load to the ditch 1 fluctuates, the rotation speed of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch, so that measurement and analysis of the nitrogen concentration are not performed. There is an effect that a good quality of treated water can be stably maintained.
[0099]
Example4).
Claims of the invention2Another embodiment according to the invention will be described with reference to the drawings. FIG. 30 shows an example.4It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 30, 8 and 18 are two dissolved oxygen concentration meters installed in a range from the installation point of the aeration rotor 2 to a point separated by 0 to 1/2 times the ditch length in the flow direction. 19 is an arithmetic unit for calculating a point at which the dissolved oxygen concentration in the itch 1 reaches a reference value of the dissolved oxygen concentration set in advance in the vicinity of 0 [mg / L] from the measured values of the dissolved oxygen concentrations 8 and 18; A signal line 8a is connected to a dissolved oxygen concentration meter 8, a signal line 18a is connected to a dissolved oxygen concentration meter 18, and a signal line 15a is connected to a setter 15 for setting a reference value of the dissolved oxygen concentration. The computing unit 19 is also connected to a controller 16 that outputs the rotational speed of the aeration rotor 2 through a signal line 19a. Others are the same as FIG.
[0100]
Next, the operation will be described. In the calculator 19, for example, according to Equation 19, the distance in the flow direction from the point where the dissolved oxygen concentration meter 8 is installed at the point where the dissolved oxygen concentration in the ditch 1 reaches a predetermined reference value of the dissolved oxygen concentration is calculated.
x = L × (DO1-DO^**) / (DO1-DO2) (19)
here,
L: Distance between the dissolved oxygen concentration meter 8 and the dissolved oxygen concentration meter 18
DO1: Measured value by dissolved oxygen concentration meter 8
DO2: Measured value by dissolved oxygen concentration meter 18
It is.
The measured values DO1 and DO2 of the dissolved oxygen concentration necessary for this calculation are obtained as the outputs of the dissolved oxygen concentration meter 8 and the dissolved oxygen concentration meter 18 through the signal line 8a and the signal line 18a. Reference value DO of dissolved oxygen concentration^**Is obtained as an output of the setting device 15 via a signal line 15a. The calculation result x is transmitted to the controller 16 via the signal line 19a.3The rotational speed of the aeration rotor 2 is adjusted in the same manner.
[0101]
In this example, the example3In addition to the above effect, since the position of the end of the aerobic region is directly calculated from the distribution of dissolved oxygen concentration, there is an effect that the rotational speed of the aeration rotor 2 can be adjusted more precisely.
[0102]
Example5.
Claims of the invention2Still another embodiment according to the present invention will be described with reference to the drawings. FIG. 31 shows an example.5It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 31, reference numeral 20 denotes a calculated value at a point where the dissolved oxygen concentration in the ditch 1 reaches a reference value preset in the vicinity of 0 [mg / L], and aeration in the ditch 1. The immersion depth of the aeration rotor 2 is set in accordance with a deviation from a target value set in advance in a range from the rotor 2 installation point to a point separated by 1/4 to 3/4 times the ditch length in the flow direction. It is a controller that outputs a target value, and is connected to the computing unit 14 through a signal line 14a. The computing unit 14 is an embodiment.3Similarly, the point at which the dissolved oxygen concentration in the ditch 1 reaches the reference value is calculated from the measured value of the dissolved oxygen concentration meter 8 and the rotational speed of the aeration rotor 2. The controller 20 calculates the target value of the height of the overflow basin 4 from the target value of the immersion depth of the aeration rotor 2 with the signal line 20a and the setting device 17 for setting the target value of the point with the signal line 17a. It is also connected to a computing unit 12 for doing this. Others are the same as FIG.
[0103]
Next, the operation will be described. In the controller 20, the target value of the immersion depth of the aeration rotor 2 is output according to, for example, Equation 20 according to the deviation between the calculated value at which the dissolved oxygen concentration in the ditch 1 reaches the reference value and the target value at that point. To do.
D_rot= D_rot0+ K_Dx(X^*-X) (20)
here,
K_Dx:constant
It is.
The calculated value x at the point where the dissolved oxygen concentration in the ditch 1 necessary for this calculation reaches the reference value is output as the output of the calculator 14 via the signal line 14a and the target value x at that point.^* Is obtained as an output of the setting device 17 via the signal line 17. Calculation result D_rot Is transmitted to the arithmetic unit 12 through the signal line 20a.
[0104]
As a result, the calculated value x at the point where the dissolved oxygen concentration reaches the reference value becomes the target value x.^* If it is smaller than this, the immersion depth of the aeration rotor 2 is increased, and the aerobic region is extended. Conversely, the calculated value x at the point where the dissolved oxygen concentration reaches the reference value is the target value x.^* If it is larger, the immersion depth of the aeration rotor 2 is reduced, and the aerobic region is shortened. That is, since the immersion depth of the aeration rotor 2 is automatically adjusted so that the end of the aerobic region is near the center of the ditch even if the inflow load to the ditch 1 fluctuates, measurement and analysis of nitrogen concentration are not performed. In addition, there is an effect that the quality of the treated water can be stably maintained.
[0105]
In addition, although the example which calculates the target value of the immersion depth which is an output of the controller 20 into the target value of the height of the overflow basin 4 by the calculator 12 was shown in FIG. Even if the arithmetic unit 12 is omitted, the same effect can be obtained.
[0106]
Example6).
Example5Shows an example of estimating the point where the dissolved oxygen concentration becomes a predetermined reference value from the measured value of the dissolved oxygen concentration and the rotation speed of the aeration rotor 2.4As shown by (2), the distribution of the dissolved oxygen concentration may be directly obtained using two or more dissolved oxygen concentration meters, and the point where the dissolved oxygen concentration becomes a predetermined reference value may be calculated. The apparatus configuration in this embodiment is almost the same as that shown in FIG. 30, but the immersion depth of the aeration rotor 2 is adjusted by the controller 20, the calculator 12, and the drive device 13 instead of the controller 16 and the drive device 3. . This gives an example5In addition to the above effect, the immersion depth of the aeration rotor 2 can be adjusted more precisely.
[0107]
Example7).
Claims of the invention3An embodiment according to the present invention will be described with reference to the drawings. FIG. 32 shows an example.7It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 32, reference numeral 21 denotes a microorganism densitometer that measures the concentration of activated sludge microorganisms in the ditch 1, and is installed at an arbitrary point in the ditch 1. Reference numeral 22 denotes an arithmetic unit for calculating a target value of dissolved oxygen concentration at a point separated by ¼ to ½ times the ditch length in the downstream direction from the installation position of the aeration rotor 2, and includes a microbial concentration meter 21 and a signal line 21a. The controller 9 is connected to the signal line 22a. Reference numeral 23 denotes a setter for setting a reference value of the dissolved oxygen concentration, which is connected to the calculator 22 through a signal line 23a. Others are the same as FIG.
[0108]
Next, the operation will be described. As described in the fourth law, the higher the MLSS concentration (active sludge microorganism concentration), the steeper the dissolved oxygen concentration distribution in the ditch. That is, the dissolved oxygen concentration slightly ahead of the end of the aerobic region is slightly larger when the activated sludge microorganism concentration is high, and slightly smaller when the activated sludge microorganism concentration is low. Therefore, the calculator 22 corrects the target value of the dissolved oxygen concentration using, for example, Equation 21.
DO^* _H= DO^*+ K_SS(MLSS-MLSS₀(21)
here,
DO^* _H   : Corrected dissolved oxygen concentration target value (correction value considering activated sludge microbial concentration)
DO^*    : Target dissolved oxygen concentration
K_SS     :constant
MLSS: Measured value of activated sludge microbial concentration
MLSS₀: Standard value of activated sludge microbial concentration
It is.
The measured value MLSS of the activated sludge microbial concentration necessary for this calculation is output as the output of the microbial concentration meter 21 via the signal line 21a and the target value DO of the dissolved oxygen concentration.^* Is obtained as an output of the setting device 23 via a signal line 23a. Operation result DO^* _HIs transmitted to the controller 9 for outputting the target value of the rotational speed of the aeration rotor 2 through the signal line 22a. Hereinafter, the embodiment shown in FIG.1Works as well.
[0109]
As a result, the measured value MLSS of the activated sludge microorganism concentration becomes the reference value MLSS.₀ Is larger than the target value DO of the dissolved oxygen concentration at a point away from the aeration rotor 2 by 1/4 to 1/2 times the ditch length in the flow direction.^* Is corrected to be larger. Therefore, it can cope with the steep gradient of the dissolved oxygen concentration distribution. Conversely, the measured value MLSS of the activated sludge microbial concentration is the reference value MLSS.₀ Less than the target value DO of dissolved oxygen concentration^* Is corrected to a smaller value. Therefore, it can cope with the dissolved oxygen concentration distribution having a gentle gradient. That is, the embodiment1In addition to the above effect, the aerobic region can be adjusted more accurately in consideration of the fourth law that “the higher the MLSS concentration, the steeper dissolved oxygen concentration distribution in the ditch”. Play.
[0110]
Example8).
Example7In the above example, the rotation speed of the aeration rotor 2 is adjusted. However, the immersion depth of the aeration rotor 2 may be adjusted. The apparatus configuration in this embodiment is almost the same as that shown in FIG. 32, but the immersion depth of the aeration rotor 2 is adjusted by the controller 11, the calculator 12, and the drive device 13 instead of the controller 9 and the drive device 3. . The computing unit 12 can be omitted. This gives an example2In addition to the above effect, the aerobic region can be adjusted more accurately in consideration of the fourth law that “the higher the MLSS concentration, the steeper dissolved oxygen concentration distribution in the ditch”. Play.
[0111]
Example9.
Claims of the invention4An embodiment according to the present invention will be described with reference to the drawings. FIG. 33 shows an example.9It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 33, reference numeral 24 indicates that the dissolved oxygen concentration in the ditch 1 is preset to a value in the vicinity of 0 [mg / L] from the measured value of the dissolved oxygen concentration, the rotational speed of the aeration rotor 2 and the measured value of the activated sludge microorganism concentration. It is a calculator that calculates a point that reaches the reference value of the dissolved oxygen concentration, and is connected to the dissolved oxygen concentration meter 8 through a signal line 8a. The dissolved oxygen concentration meter 8 is installed in a range from the installation point of the aeration rotor 2 to a point separated by 0 to 1/2 times the ditch length in the flow direction. The computing unit 24 is also connected to the aeration rotor 2 by a signal line 2a and a setting unit 15 for setting a reference value of the dissolved oxygen concentration by a signal line 15a. The signal line 21a is also connected to the microorganism concentration meter 21 and the signal line 24a is connected to the controller 16 that outputs a target value of the rotational speed of the aeration rotor 2. Others are the same as FIG.
[0112]
Next, the operation will be described. The calculator 24 calculates a point where the dissolved oxygen concentration in the ditch 1 reaches a predetermined reference value of the dissolved oxygen concentration by, for example, Expression 17 and Expression 22.
x_H= XxRr₀/ Rr (MLSS)
Rr (MLSS) = Rr₀+ K_MLSS(MLSS-MLSS₀(22)
here,

It is.
The measured value MLSS of the activated sludge microbial concentration necessary for the calculation of Expression 22 is obtained as the output of the microbial concentration meter 21 via the signal line 21a. Operation result x_H Is transmitted to the controller 16 that outputs the target value of the rotational speed of the aeration rotor 2 via the signal line 24a.3Works as well.
[0113]
As a result, when the measured value MLSS of the activated sludge microorganism concentration is large, the dissolved oxygen consumption rate term Rr (MLSS) becomes large, so the distance x of the reference value reaching point_H Is corrected to be shorter than the distance x. Therefore, it can cope with the steep gradient of the dissolved oxygen concentration distribution. Conversely, when the measured value MLSS of the activated sludge microbial concentration is small, the dissolved oxygen consumption rate term Rr (MLSS) is small, so the distance x of the reference value reaching point_H Is corrected longer than the distance x. Therefore, it can cope with the dissolved oxygen concentration distribution having a gentle gradient. That is, the embodiment3In addition to the above effect, the aerobic region can be adjusted more accurately in consideration of the fourth law that “the higher the MLSS concentration, the steeper dissolved oxygen concentration distribution in the ditch”. Play.
[0114]
Example10.
Example above9In the above example, the rotation speed of the aeration rotor 2 is adjusted. However, the immersion depth of the aeration rotor 2 may be adjusted. The apparatus configuration in this embodiment is almost the same as that shown in FIG. 33, but the immersion depth of the aeration rotor 2 is adjusted by the controller 20, the calculator 12, and the drive device 13 instead of the controller 16 and the drive device 3. . The computing unit 12 can be omitted. This gives an example5In addition to the above effect, the aerobic region can be adjusted more accurately in consideration of the fourth law that “the higher the MLSS concentration, the steeper dissolved oxygen concentration distribution in the ditch”. Play.
[0115]
Example11.
Claims of the invention7An embodiment according to the present invention will be described with reference to the drawings. FIG. 34 shows an example.11It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 34, reference numeral 25 denotes a total nitrogen concentration meter attached to a pipe c for discharging the precipitated treated water. A storage circuit 26 stores the relationship between the MLSS concentration in the ditch 1 and the total nitrogen concentration in the treated water, and is connected to the total nitrogen concentration meter 25 through a signal line 25a. The calculator 22 calculates the target value of the dissolved oxygen concentration at a point away from the installation point of the aeration rotor 2 by ¼ to ½ times the ditch length in the flow direction. Reference numeral 27 denotes a setter for setting a target value of the total nitrogen concentration in the treated water, which is connected to the storage circuit 26 through a signal line 27a. 28 is a controller that outputs the amount of excess sludge extraction according to the deviation between the target value of MLLS concentration output from the memory circuit 26 and the measured value of MLSS concentration. Are connected to a microorganism concentration (MLSS concentration) meter 21 and a surplus sludge extraction pump 6 through a signal line 28a. Others are the same as FIG.
[0116]
Next, the operation will be described. The total nitrogen concentration in the treated water is measured by a total nitrogen concentration meter 25 attached to the pipe c. The measured value of the total nitrogen concentration is transmitted to the storage circuit 26 via the signal line 25a. The storage circuit 26 determines the target value of the MLSS concentration in the ditch 1 from the measured value of the total nitrogen concentration in the treated water and the predetermined target value of the total nitrogen concentration. A target value for the total nitrogen concentration in the treated water is set by the setting device 27. Only one target value may be set, or two upper limit values and lower limit values may be set. Here, for the sake of brevity, the former case will be described. The set target value is transmitted to the memory circuit 26 through the signal line 27a.
[0117]
The storage circuit 26 stores the relationship between the MLSS concentration in the ditch 1 and the total nitrogen concentration in the treated water. That is, in order to remove nitrogen highly, it was shown that the MLSS concentration needs to be kept high (second law), but FIG. 35 is an example of obtaining the optimum water quality, and the horizontal axis is Ditch 1. The MLSS concentration [mg / L] is shown, and the vertical axis shows the total nitrogen concentration [mg / L] in the treated water. The curve in the figure shows the relationship between the total nitrogen concentration and the MLSS concentration when the treated water quality is the best among the simulation results obtained by changing the rotor conditions for a certain inflow load. An algorithm for determining the target value of the MLSS concentration in the ditch 1 from the measured value of the total nitrogen concentration in the treated water and a predetermined target value will be described with reference to FIG.
[0118]
Flow rate as planned, for example, 15 [m in FIG.^Three / H], when the sewage flows in, the MLSS concentration is set so as to obtain the treated water quality as the target value (point A). If the total nitrogen concentration measurement is worse than the target value, the inflow rate should have increased. Therefore, the inflow rate is estimated from the combination of the measured value of the total nitrogen concentration and the current MLSS concentration initially set (point B). For example, in FIG. 35, 20 [m^Three / H]. A new MLSS concentration target value for obtaining the target water quality is determined according to the MLSS concentration-total nitrogen concentration curve using the new inflow rate as a parameter (point C). Similarly, when the measured value of the total nitrogen concentration is better than the target value, a new MLSS concentration target value can be determined. This new MLSS concentration target value is transmitted to the controller 28. The controller 28 outputs the target value of the excess sludge extraction amount according to, for example, Equation 23.
Q_drw= Q_drw0+ K_SS(MLSS^*-MLSS) (23)
here,
Q_drw    : Target value of excess sludge extraction
Q_drw0   :constant
K_SS     :constant
MLSS^*: Target value of MLSS concentration in Ditch 1 (new MLSS)
It is.
[0119]
As described above, the target value MLSS of the MLSS concentration in the ditch 1^* Is obtained as an output of the memory circuit 26 via a signal line 26a. Further, the measured value MLSS of the MLSS concentration in the ditch 1 is obtained from the microorganism concentration meter 21 through the signal line 21b. The output of the controller 28 is transmitted to the excess sludge extraction pump 6 via the signal line 28a, and the excess sludge is extracted by a predetermined amount.
[0120]
This maintains the optimal MLSS concentration to achieve the target water quality. On the other hand, since the rotation speed of the aeration rotor 2 is adjusted while correcting the measurement value of the MLSS densitometer 21,7In addition to the above effect, it is possible to obtain a more stable and good treated water quality, and at the same time, an effect that the amount of activated sludge microorganisms in the system is not excessive or deficient.
[0121]
Example12
Claims of the invention7Another embodiment according to the invention will be described with reference to the drawings. FIG. 36 shows an example.12It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 36, 29 is an arithmetic unit for calculating the target value of the MLSS concentration in the ditch 1 in accordance with the deviation between the measured value of the total nitrogen concentration meter 25 and a predetermined target value, and is connected to the pipe c by the signal line 25a. The attached total nitrogen concentration meter 25, a setter 27 for setting a target value of the total nitrogen concentration with a signal line 27a, and a controller 28 for removing excess sludge are connected with a signal line 29a. Others are the same as FIG.
[0122]
Next, the operation will be described. The calculator 29 outputs the target value of the MLSS concentration in the ditch 1 according to, for example, Expression 24.
MLSS^*= MLSS₀+ K_TN1(TN^*-TN) (24)
here,
MLSS₀:constant
K_TN1    :constant
TN^*    : Total nitrogen concentration target value
TN: Measurement value of total nitrogen concentration
It is.
Target value TN of total nitrogen concentration required for this calculation^* Is obtained via the signal line 27a as the output of the setting device 27, and the measured value TN of the total nitrogen concentration is obtained as the output of the total nitrogen concentration meter 25 via the signal line 25a. Operation result MLSS^* Is transmitted to the controller 28 via the signal line 29a.
[0123]
Thereby, the measured value TN of the total nitrogen concentration becomes the target value TN.^* If it is larger than that, the amount of excess sludge withdrawn decreases, and the total amount of sludge retained in the system increases. Therefore, since the MLSS concentration in the ditch 1 increases, the total nitrogen concentration in the treated water tends to decrease. Conversely, the measured value TN of the total nitrogen concentration is the target value TN.^* If it is smaller than that, the amount of excess sludge extraction increases, and the total amount of sludge retained in the system decreases. On the other hand, the rotation speed of the aeration rotor 2 is adjusted while performing correction based on the measurement value of the MLSS densitometer 21. That is, since the optimum MLSS concentration is maintained in order to achieve the target water quality, and the rotation speed of the aeration rotor 2 is adjusted so as to obtain an optimum aerobic region length for the MLSS concentration, the embodiment11Has the same effect as. In this embodiment, the target value MLSS of the MLSS concentration^* Therefore, the configuration is simpler than that of the twenty-third embodiment using the memory circuit 26.
[0124]
Example13.
Example above11, 12In the example in which the control target value of the dissolved oxygen concentration in a specific section in the ditch is corrected using the optimized reference value of the MLSS concentration and the measured value of the MLSS concentration, it is optimal for achieving the target water quality. Although the MLSS concentration is calculated and the amount of sludge withdrawn is controlled so as to be the target value of this MLSS concentration, it may not be corrected. As an apparatus configuration of the embodiment in this case, a setting device 10 is provided instead of omitting the calculator 22 and the setting device 23 in FIGS. 34 and 36, and the setting of the dissolved oxygen concentration target value is performed by the setting device 10. Can be considered. This gives an example11, 12The same effect can be obtained with a simpler device configuration. Further, as an apparatus configuration similar to this, the microbial concentration meter 21, the storage circuit 26, the setting device 27 and the controller 28 are provided in FIGS. 19 to 26, and the total nitrogen concentration meter 25 or the nitrate nitrogen concentration meter 100 and A configuration in which the excess sludge extraction amount is adjusted using an output signal from the ammonia nitrogen concentration meter 101 can be considered. As a result, the optimum MLSS concentration is maintained to achieve the target water quality, and at the same time, the aerobic region length is also appropriately controlled.Reference exampleIn addition to the effects 1 to 12, it is possible to obtain a more stable and good treated water quality, and at the same time, an effect that the amount of activated sludge microorganisms in the system is not excessive or deficient.
[0125]
Example14
Claims of the invention7Still another embodiment according to the present invention will be described with reference to the drawings. FIG. 37 shows an example.14It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 37, the memory circuit 26 and the arithmetic unit 22 are connected by a signal line 26b. Example above11In the example of correcting the control target value of the dissolved oxygen concentration in a specific section in the ditch using the measured MLSS concentration, the optimum MLSS concentration is calculated to achieve the target water quality, and the target of this MLSS concentration is calculated. Although the amount of sludge extraction was controlled so as to be a value, the measured MLSS concentration will eventually become the target value of the MLSS concentration.14Then, the target value MLSS of the MLSS concentration output from the storage circuit 26^* Was input to the calculator 22 instead of the measured MLSS concentration, and the target value of the dissolved oxygen concentration was corrected.
By doing in this way, it can respond quickly so that there may be no excess and deficiency in the amount of microorganisms for performing a water treatment.
[0126]
Example15.
Example12Example for14As with, the target value MLSS of the MLSS concentration output from the calculator 29^* May be input to the calculator 22 and used in place of the measured MLSS concentration when correcting the target value of the dissolved oxygen concentration.
[0127]
Example16.
Claims of the invention8An embodiment according to the present invention will be described with reference to the drawings. FIG. 38 shows an example.16It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 38, 30 is a controller that outputs a target value of the excess sludge extraction amount in accordance with a deviation between a measured value of the total nitrogen concentration meter 25 and a predetermined total nitrogen concentration target value. The total nitrogen concentration meter 25 attached to c is connected to the excess sludge extraction pump 6 through a signal line 30a. Reference numeral 27 denotes a setter for setting a target value for the total nitrogen concentration, which is connected to the controller 30 through a signal line 27a. Others are the same as FIG.
[0128]
Next, the operation will be described. The controller 30 outputs the target value of the excess sludge extraction amount according to, for example, Equation 25.
Q_drw= Q_drw0+ K_drw(TN^*-TN) (25)
here,
K_TN2:constant
It is.
Target value TN of total nitrogen concentration required for this calculation^* Is obtained via the signal line 27a as the output of the setting device 27, and the measured value TN of the total nitrogen concentration is obtained as the output of the total nitrogen concentration meter 25 via the signal line 25a. Calculation result Q_drw Is transmitted to the excess sludge extraction pump 6 via the signal line 30a.
[0129]
Thereby, the measured value TN of the total nitrogen concentration becomes the target value TN.^* If it is larger than that, the amount of excess sludge withdrawn decreases, and the total amount of sludge retained in the system increases. Therefore, since the MLSS concentration in the ditch 1 increases, the total nitrogen concentration in the treated water tends to decrease. Conversely, the measured value TN of the total nitrogen concentration is the target value TN.^* If it is smaller than that, the amount of excess sludge extraction increases, and the total amount of sludge retained in the system decreases. On the other hand, the rotation speed of the aeration rotor 2 is adjusted while performing correction based on the measurement value of the MLSS densitometer 21. That is, since the optimum MLSS concentration is maintained in order to achieve the target water quality, and the rotation speed of the aeration rotor 2 is adjusted so as to obtain an optimum aerobic region length for the MLSS concentration, the embodiment7In addition to the above effect, it is possible to obtain a more stable and good treated water quality, and at the same time, an effect that the amount of activated sludge microorganisms in the system is not excessive or deficient.
[0130]
Example17.
Example above16In the example of correcting the control target value of the dissolved oxygen concentration in a specific section in the ditch using the optimized reference value of MLSS concentration, the amount of sludge extraction was controlled to achieve the target water quality. The correction may not be performed. As an apparatus configuration of the embodiment in this case, a setting device 10 is provided instead of omitting the microorganism concentration meter 21, the calculator 22, and the setting device 23 in FIG. 38, and the setting of the dissolved oxygen concentration target value is performed by the setting device 10. A configuration to perform is conceivable. This gives an example16The same effect can be obtained with a simpler device configuration. Further, as a device configuration similar to this, the setting device 27 and the controller 30 are provided in FIGS. 19 to 26, and outputs from the total nitrogen concentration meter 25, or the nitrate nitrogen concentration meter 100 and the ammonia nitrogen concentration meter 101. A configuration may be considered in which the amount of excess sludge extraction is adjusted using a signal. As a result, the optimum MLSS concentration is maintained to achieve the target water quality, and at the same time, the aerobic region length is also appropriately controlled.Reference exampleIn addition to the effects 1 to 12, it is possible to obtain a more stable and good treated water quality, and at the same time, an effect that the amount of activated sludge microorganisms in the system is not excessive or deficient.
[0131]
Example18.
Example above11-17Then, although the example which adjusts the rotation speed of the aeration rotor 2 was shown, you may adjust the immersion depth of the aeration rotor 2. FIG. The apparatus configuration of this embodiment is almost the same as that shown in FIGS. 34, 36, 37, and 38, but the controller 11, the calculator 12, and the drive device 13 replace the controller 9 and the drive device 3. Adjust immersion depth. The computing unit 12 can be omitted. This gives an example2Or example8In addition to the above effect, stable and good treated water quality can be obtained, and at the same time, the amount of activated sludge microorganisms in the system can be prevented from being excessive or insufficient.
[0132]
Example19.
Example11-18Then, although the example which adjusts the rotation speed or immersion depth of the aeration rotor 2 using the measured value of the dissolved oxygen concentration of the specific area in the ditch 1 was shown,3-6, 9, 10Alternatively, it is possible to estimate a point where the dissolved oxygen concentration becomes a predetermined reference value and adjust the rotational speed or immersion depth of the aeration rotor 2 so that the dissolved oxygen concentration is always at a predetermined point. The apparatus configuration in this embodiment is almost the same as that shown in FIGS. 34, 36, 37, and 38. For example, when the rotation speed is adjusted, the configuration of that portion is as shown in FIG. When adjusting the immersion depth, the immersion depth of the aeration rotor 2 is adjusted by the controller 20, the calculator 12, and the drive device 13 instead of the controller 16 and the drive device 3. The computing unit 12 can be omitted. This gives an example3-6, 9, 10In addition to the above effect, stable and good treated water quality can be obtained, and at the same time, the amount of activated sludge microorganisms in the system can be prevented from being excessive or insufficient.
[0133]
Example20.
Example11-19Then, although the example which measures the total nitrogen concentration in treated water was shown, as long as it is a parameter | index which shows the water quality of treated water, not only this but organic substance concentration, total phosphorus concentration, etc. may be measured.
[0134]
Example21.
Reference example1-12,Examples 11-20Then, although the example which installs the means for measuring the quality of treated water, such as the nitrate nitrogen concentration meter 100 and the ammonia nitrogen concentration meter 101, in the pipe c for discharging the precipitated treated water, the order of installing these concentration meters is as follows. Whichever is better. The means for measuring the quality of the treated water may be installed in the vicinity of the treated water outflow point in the pipe b for introducing the effluent from the ditch 1 into the sedimentation basin 5 or in the ditch 1.
[0135]
Example22.
Claims of the invention5An embodiment according to the present invention will be described with reference to the drawings. FIG. 39 shows an example.22It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 39, 31 is a thermometer for measuring the water temperature in the ditch 1, and is installed at an arbitrary point in the ditch. 32 is an arithmetic unit for calculating the target value of the dissolved oxygen concentration at a point separated by ¼ to ½ times the ditch length in the flow direction from the installation position of the aeration rotor 2, and includes a thermometer 31 and a signal line 31a. The controller 9 is connected to the signal line 32a. Reference numeral 33 denotes a setter for setting a parameter for calculating a target value of the dissolved oxygen concentration, which is connected to the calculator 32 through a signal line 33a. Others are the same as FIG.
[0136]
Next, the operation will be described. As described in the third law, the optimum end position of the aerobic region with respect to the treated water quality is affected by variations in factors that affect microbial activity, such as water temperature, pH, and oxidation-reduction potential. In detail, when the nitrification speed is larger than the denitrification speed, it shifts forward (aeration rotor side), and when the denitrification speed is larger than the nitrification speed, it shifts backward. Therefore, the calculator 32 calculates the target value of the dissolved oxygen concentration, for example, according to Equation 26.
DO_H1 ^*= DO^*× K_Dθ_D ^T-20/ K_Nθ_N ^T-20              ... (26)
here,
DO_H1 ^*  : Target dissolved oxygen concentration (correction value considering water temperature)
K_D      : Denitrification rate when water temperature is 20 ° C
θ_D      :constant
K_N      : Nitrification rate when water temperature is 20 ° C
θ_N      :constant
T: temperature
It is.
The water temperature T in the ditch 1 necessary for this calculation is obtained via the signal line 31a as the output of the thermometer 31, and the parameters for calculation are obtained via the signal line 33a as the output of the setting device 33. Operation result DO_H1 ^*Is transmitted to the controller 9 that outputs a target value of the rotational speed of the aeration rotor 2 via a signal line 32a.
[0137]
As a result, when the denitrification rate is higher than the nitrification rate, the target value of the dissolved oxygen concentration at a point separated from the aeration rotor 2 by ¼ to ½ times the ditch length in the flow direction is corrected to be larger. Therefore, it is possible to cope with the rear end position of the aerobic region optimum for the treated water quality being shifted backward from the vicinity of the center of the ditch. Conversely, when the nitrification rate is higher than the denitrification rate, the target value of the dissolved oxygen concentration is corrected to be smaller. Therefore, it is possible to cope with the end position of the aerobic region optimum for the quality of the treated water being shifted backward from the vicinity of the center of the ditch. That is, the embodiment1In addition to the above effect, the third law that “the end position of the aerobic region optimal for the treated water quality is affected by fluctuations in factors affecting the microbial activity such as water temperature, pH, redox potential” is considered As a result, the aerobic region can be adjusted more accurately.
[0138]
Example23.
Example22In the above example, the rotation speed of the aeration rotor 2 is adjusted. However, the immersion depth of the aeration rotor 2 may be adjusted. The apparatus configuration in this embodiment is almost the same as that shown in FIG. 39, but the immersion depth of the aeration rotor 2 is adjusted by the controller 11, the calculator 12, and the drive device 13 instead of the controller 9 and the drive device 3. . The computing unit 12 can be omitted. This gives an example2In addition to the above effect, the third law that “the end position of the aerobic region optimal for the treated water quality is affected by fluctuations in factors affecting the microbial activity such as water temperature, pH, redox potential” is considered As a result, the aerobic region can be adjusted more accurately.
[0139]
Example24.
Claims of the invention6An embodiment according to the present invention will be described with reference to the drawings. FIG. 40 shows an example.24It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 40, 34 is set in advance so that the dissolved oxygen concentration in the ditch 1 is in the vicinity of 0 [mg / L] from the measured value of the dissolved oxygen concentration, the rotational speed of the aeration rotor 2 and the measured value of the water temperature in the ditch 1. It is a calculator that calculates a point that reaches the reference value of the dissolved oxygen concentration, and is connected to the dissolved oxygen concentration meter 8 through a signal line 8a. The dissolved oxygen concentration meter 8 is installed in a range from the installation point of the aeration rotor 2 to a point separated by 0 to 1/2 times the ditch length in the flow direction. The computing unit 34 is also connected to the aeration rotor 2 by the signal line 2a and the setting unit 15 for setting the reference value of the dissolved oxygen concentration by the signal line 15a. Further, the thermometer 31 is connected with the signal line 31a, and the controller 16 that outputs the target value of the rotational speed of the aeration rotor 2 with the signal line 34a. Others are the same as FIG.
[0140]
Next, the operation will be described. The calculator 34 calculates a point where the dissolved oxygen concentration in the ditch 1 reaches a predetermined reference value of the dissolved oxygen concentration by, for example, Expression 17 and Expression 27.
X_H2= X × K_Dθ_D ^T-20/ K_Nθ_N ^T-20                   ... (27)
here,
X_H2: Distance in the flow direction from the point where the dissolved oxygen concentration meter 8 is installed at the point where the dissolved oxygen concentration in the ditch 1 reaches the predetermined reference value of the dissolved oxygen concentration (correction value considering the water temperature)
It is.
The measured value of the activated sludge microbial concentration necessary for the calculation of Expression 27 is obtained as the output of the microbial concentration meter 31 via the signal line 31a. Calculation result X_H2Is transmitted to the controller 16 that outputs a target value of the rotational speed of the aeration rotor 2 via a signal line 34a.
[0141]
Thereby, when the denitrification rate is larger than the nitrification rate, the distance X of the reference point of the dissolved oxygen concentration is reached._H2Is corrected longer than the distance X. Therefore, it is possible to cope with the rear end position of the aerobic region optimum for the treated water quality being shifted backward from the vicinity of the center of the ditch. Conversely, when the nitrification rate is greater than the denitrification rate, the distance X of the reference point for the dissolved oxygen concentration X_H2Is corrected to be shorter than the distance X. Therefore, it is possible to cope with the end position of the aerobic region optimum for the quality of the treated water being shifted backward from the vicinity of the center of the ditch. That is, the embodiment3In addition to the above effect, the third law that “the end position of the aerobic region optimal for the treated water quality is affected by fluctuations in factors affecting the microbial activity such as water temperature, pH, redox potential” is considered As a result, the aerobic region can be adjusted more accurately.
[0142]
Example25.
Example24In the above example, the rotation speed of the aeration rotor 2 is adjusted. However, the immersion depth of the aeration rotor 2 may be adjusted. The apparatus configuration of the embodiment in this case is almost the same as that of FIG. 40, but the immersion depth of the aeration rotor 2 is adjusted by the controller 20, the calculator 12, and the drive device 13 instead of the controller 16 and the drive device 3. . The computing unit 12 can be omitted. This gives an example5In addition to the above effect, the third law that “the end position of the aerobic region optimal for the treated water quality is affected by fluctuations in factors affecting the microbial activity such as water temperature, pH, redox potential” is considered As a result, the aerobic region can be adjusted more accurately.
[0143]
Example26.
Example22-25Shows an example in which the target value of the dissolved oxygen concentration in a specific section in the ditch 1 is corrected considering only the water temperature.7-21As described above, correction in consideration of the MLSS concentration may be performed at the same time. The apparatus configuration in this embodiment is almost the same as that shown in FIGS. 32 and 33 or FIGS. 34 and 36. However, the signal from the water temperature gauge 31 is input to the computing unit 22 via the signal line 31a and aerated by, for example, Expression 28. The target value of the dissolved oxygen concentration at a point away from the rotor 2 installation point by ¼ to ½ times the ditch length in the flow direction is calculated.
DO_H2 ^*= DO_H ^*× K_Dθ_D ^T-20/ K_Nθ_N ^T-20            ... (28)
[0144]
Alternatively, a signal from the water temperature gauge 31 is input to the calculator 24 via the signal line 31a, and the point where the dissolved oxygen concentration in the dicchi 1 reaches a predetermined reference value of the dissolved oxygen concentration is calculated by, for example, Equation 29.
X_H2= X_H× K_Dθ_D ^T-20/ K_Nθ_N ^T-20                  ... (29)
[0145]
When adjusting the immersion depth of the aeration rotor 2, the controller 9 or 16 and the controller 11 or 20, the calculator 12, and the driver 13 are used instead of the driver 3. The computing unit 12 can be omitted.
[0146]
This gives an example7-21In addition to the above effect, the third law that “the end position of the aerobic region optimal for the treated water quality is affected by fluctuations in factors affecting the microbial activity such as water temperature, pH, redox potential” is considered As a result, the aerobic region can be adjusted more accurately.
[0147]
Example27.
Example22-26Shows an example using a thermometer, but the same effect can be obtained by using a pH meter or an oxidation-reduction potentiometer. In this case, instead of the calculations shown in the formulas 26 to 29, the calculation considering the influence of the pH or oxidation-reduction potential on the nitrification rate and the denitrification rate is performed.
[0148]
Example28.
Claims of the invention9An embodiment according to the present invention will be described with reference to the drawings. FIG. 41 shows an example.28It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 41, 35 is a flow meter attached to the pipe a for introducing sewage into the ditch 1. Reference numeral 36 denotes a calculator that calculates a reference value for the rotational speed of the aeration rotor 2, and is connected to a flow meter 35 through a signal line 35a and a controller 9 that calculates a target value of the rotational speed of the aeration rotor 2 through a signal line 35a. ing. Others are the same as FIG.
[0149]
Next, the operation will be described. Example1As shown in Fig. 5, the dissolved oxygen concentration in a specific section in the ditch 1 is measured, and the dissolved oxygen concentration at the measurement point is kept constant by adjusting the rotation speed of the aeration rotor 2 using this measured value. If it does so, an aerobic area | region and an anaerobic area | region can be formed appropriately in the ditch 1, and a favorable treated water quality can be obtained. However, with this method, the adjustment of the aeration rotor is performed only after the biochemical reaction in the tank progresses and the dissolved oxygen concentration changes, so there is a possibility that the response will be delayed when there is a sudden inflow load fluctuation. There is. Therefore, the flow rate of the sewage flowing into the ditch 1 is measured, and the balance between the aerobic region and the anaerobic region is adjusted after adjusting the reference value of the rotational speed of the aeration rotor 2 in advance using the measured value. By doing so, it is possible to stably maintain a good quality of treated water even against a sudden change in the inflow rate.
[0150]
The flow rate of the sewage flowing into the ditch 1 is measured by the flow meter 35 attached to the pipe a, and is transmitted to the calculator 36 through the signal line 35a. In the computing unit 36, for example, the reference value R of the rotational speed of the aeration rotor 2 is obtained by Equation 30_rot0Is calculated.
R_rot0= K_QinQ_in                                  ... (30)
here,
K_Qin:constant
Q_in : Flow rate of sewage flowing into Ditch 1
It is.
This calculation result is transmitted to the controller 9 that calculates the target value of the rotational speed of the aeration rotor 2 via the signal line 35a.
[0151]
Thereby, when the inflow flow rate is large, the reference value of the rotational speed of the aeration rotor 2 is set to be large in advance. Conversely, when the inflow flow rate is small, the reference value for the rotational speed of the aeration rotor 2 is set to be small in advance. Thereby, in addition to the effect of Example 13, there exists an effect that the favorable quality of treated water can be maintained stably also to the fluctuation | variation of the rapid inflow flow rate.
[0152]
Example29.
Example28In the above example, the rotation speed of the aeration rotor 2 is adjusted. However, the immersion depth of the aeration rotor 2 may be adjusted. The apparatus configuration in this embodiment is almost the same as that shown in FIG. 41. However, instead of the controller 9 and the drive device 3, the controller 11 is composed of the controller 11, the calculator 12 and the drive device 13, and the calculation result of the calculator 34 ( The reference value of the immersion depth of the aeration rotor 2) is input to the controller 11. The computing unit 12 can be omitted. This gives an example2In addition to the effect of the above, there is an effect that it is possible to stably maintain a good quality of treated water even against a sudden change in the inflow rate.
[0153]
Example30.
Example28, 29Shows an example of adjusting the rotation speed or immersion depth of the aeration rotor 2 using the measured value of the dissolved oxygen concentration in a specific section in the ditch 1, but estimates the point where the dissolved oxygen concentration becomes a predetermined reference value. However, the dissolved oxygen concentration or the standard in consideration of the microbial activity such as microbial concentration, temperature, pH, redox potential, etc. The same effect can be obtained by correcting the value arrival point, of course, adjusting the rotation speed or immersion depth of the aeration rotor 2 using the concentration difference or concentration ratio of nitrate nitrogen concentration, ammonia nitrogen concentration and total nitrogen concentration. Play. As in FIG. 41, the apparatus configuration of the embodiment in these cases may be provided with the flow meter 35 and the calculator 36, and the calculation result of the calculator 36 is transferred to the rotation speed controller or the immersion depth controller of the aeration rotor 2. input.
[0154]
Example31.
Example28-30In the above example, the measured value of the inflow flow rate of sewage to the ditch 1 is shown, but the same effect can be obtained by using the measured value of the outflow flow rate from the ditch 1.
[0155]
Example32.
Example28-30In the above example, the measured value of the inflow rate of sewage to the ditch 1 is shown, but the same effect can be obtained by using the measured value of the concentration of inflowing contaminants, for example, total nitrogen.
[0156]
Example33.
Example28-30In the above example, the measured value of the inflow flow rate of sewage to the ditch 1 is shown, but the same effect can be obtained by using the inflowing pollutant, for example, the inflowing total nitrogen amount multiplied by the total nitrogen concentration.
[0157]
Reference Example 13
The present inventionReference examples related toWill be described with reference to FIG. FIG.Reference Example 13It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus which concerns on this. In FIG. 42, 37 is a flow meter attached to the pipe b for introducing the effluent water from the ditch 1 into the sedimentation basin 5. Reference numeral 38 denotes a controller that outputs a target value of the height of the overflow basin 4, and is connected to the flow meter 37 via a signal line 37a and to the drive device 13 of the overflow basin 4 via a signal line 38a. Others are the same as FIG.
[0158]
Next, the operation will be described. The flow rate flowing out of the ditch 1 is measured by the flow meter 37 attached to the pipe b and transmitted to the controller 38 via the signal line 37a. In the controller 38, for example, the target value of the height of the overflow basin 4 is calculated by Equation 31.
H = H₀+ K_Qout(Q_out-Q_out0(31)
here,
K_Qout:coefficient
Q_out : Flow out of Ditch 1
Q_out0: Standard value of flow rate flowing out of Ditch 1
It is.
The calculation result H is transmitted to the driving device 13 through the signal line 38a, and the height of the overflow dam 4 is adjusted.
[0159]
Thereby, the flow rate Q flowing out of the ditch 1_out Is the reference value Q_out0If it is larger, the height H of the overflow dam 4 is increased, the outflow amount, that is, the inflow amount into the sedimentation basin 5 is reduced, and at the same time, the immersion depth of the aeration rotor 2 is increased and the aeration amount is increased. Conversely, the flow rate Q flowing out of the ditch 1_out Is the reference value Q_out0If it is smaller than this, the height H of the overflow dam 4 is lowered, the outflow amount, that is, the inflow amount into the sedimentation basin 5 is increased, and at the same time, the immersion depth of the aeration rotor 2 is reduced and the aeration amount is reduced. That is, even if the flow rate of the sewage flowing into the ditch 1 fluctuates, the flow rate flowing out to the sedimentation basin 5 is always kept constant, and the solid-liquid separation process is effectively performed in the sedimentation basin 5. Furthermore, there is an effect that the immersion depth of the aeration rotor 2 can be adjusted at the same time.
[0160]
Example34.
Example aboveAnd reference examplesIn the example of adjusting the immersion depth of the aeration rotor, the case where the height of overflow overflow was changed was described, but the installation position of the aeration rotor itself should be changed.SameHas the same effect.
[0161]
Each example described aboveAnd reference examplesIn the above description, the case where the aeration rotor is used has been described, but the present invention can also be applied to the case where other aeration devices such as an axial flow pump type aeration device and a screw type aeration device are used.
[0162]
In addition, each of the above embodimentsAnd reference examplesIn the above, the case of removing nitrogen is shown, but the present invention can also be applied to the case of removing other contaminants such as organic matter or phosphorus.
[0163]
Further, each of the above embodimentsAnd reference examplesIn, it was configured with a time-continuous analog type, but with a time-discontinuous analog type (sample value type) or digital typeSameHas the same effect.
[0164]
In addition, the above embodimentAnd reference examplesThen, the control circuit configuration was shown, but this was programmed and implemented in the computer.SameHas the same effect.
[0165]
In the above embodiment,And reference examplesAlthough the control circuit is configured in a closed loop, it can also be configured as a driving support system that presents the control target value to the operator.
[0166]
【The invention's effect】
  As described above, according to the invention of claim 1, the control device for the oxidation ditch water treatment device is used as the aeration device.Within the ditch1/4 to 1/2 of the ditch length in the flow direction from the installation pointDoublingTo measure the dissolved oxygen concentration at any point in the specified area,the aboveMeasured value of dissolved oxygen concentration and,Preset to a value between 0 and 1 [mg / liter]the aboveDepending on the deviation of the dissolved oxygen concentration from the target value,the aboveAeration equipmentIn the above ditchInstallation point andIn the above ditchSo that the boundary between the aerobic region and the anaerobic region is near the center of the treated water outflow point,Aeration deviceController that outputs the target value of rotation speed or immersion depthAnd aboveAccording to the target value of the rotation speed or the above immersion depthThe aeration deviceAdjust the rotation speed or immersion depthA configuration with adjusting means;Therefore, it is possible to automatically adjust the end of the aerobic region to be near the center of the ditch without performing nitrogen concentration measurement and analysis, and to maintain stable quality of the treated water There is.
[0167]
  Further, according to the invention of claim 2, the control device for the oxidation ditch water treatment device is provided as an aeration device.Within the ditchAt least one or more dissolved oxygen concentration measuring means installed in the range 0 to 1/2 times the ditch length in the flow direction from the installation point, Measured by this dissolved oxygen concentration measuring meansUsing measured values of dissolved oxygen concentration,The dissolved oxygen concentration in the ditch,Calculation means for calculating a point that reaches a reference value of the dissolved oxygen concentration preset to a value in the vicinity of 0 [mg / liter]The calculated value calculated by the calculating means, the installation point of the aeration apparatus in the ditch, and the treated water outflow point in the ditchPreset near the center ofReach the above reference valueDepending on the deviation from the target value of the point,the aboveAeration equipmentIn the above ditchInstallation point andIn the above ditchSo that the boundary between the aerobic region and the anaerobic region is near the center of the treated water outflow point,Aeration deviceController that outputs the target value of rotation speed or immersion depthAnd aboveSpeed orthe aboveAccording to the target value of immersion depthThe aeration deviceAdjust the rotation speed or immersion depthA configuration with adjusting means;Therefore, the rotation speed of the aeration rotor can be automatically adjusted so that the end of the aerobic region is near the center of the ditch without performing nitrogen concentration measurement and analysis, and stable treated water quality can be stabilized. There is an effect that can be maintained.
[0168]
Claims3According to the invention, since the target value of the dissolved oxygen concentration is corrected from the measured value of the activated sludge microbial concentration at any point in the ditch or the target value of the activated sludge microbial concentration, a more accurate aerobic region Therefore, there is an effect that good treated water quality can be stably maintained.
[0169]
Claims4According to the invention of the present invention, the point where the dissolved oxygen concentration reaches the reference value is corrected from the measured value of the activated sludge microbial concentration at any point in the ditch or the target value of the activated sludge microbial concentration. The aerobic region can be adjusted, and the effect of being able to stably maintain good treated water qualityis there.
[0170]
Claims5According to the invention, means for measuring at least one of water temperature, pH, oxidation-reduction potential is provided at an arbitrary point in the ditch, and the target value of the dissolved oxygen concentration is corrected from these measured values. There is an effect that the aerobic region can be adjusted more accurately, and good treated water quality can be stably maintained.
[0171]
Claims6According to the invention, means for measuring at least one of the water temperature, pH, and oxidation-reduction potential is provided at an arbitrary point in the ditch, and the target value at the point where the dissolved oxygen concentration reaches the reference value is corrected from these measured values. Thus, there is an effect that the aerobic region can be adjusted more accurately and good treated water quality can be stably maintained.
[0172]
Further, according to the invention of claim 7, the control device for the oxidation ditch water treatment apparatus comprises means for measuring the concentration of activated sludge microorganisms installed at an arbitrary point in the ditch and means for measuring the quality of the treated water. And a calculator for calculating the target value of the activated sludge microbial concentration according to the deviation between the measured value of the water quality and the predetermined target value, and the sludge according to the deviation between the target value of the activated sludge microbial concentration and the measured value. Since the controller for outputting the target value of the extraction amount and the means for adjusting the sludge extraction amount according to the target value of the sludge extraction amount are provided, the aerobic region and the anaerobic region are appropriately formed in the ditch. At the same time, there is an effect that there is no excess or deficiency in the amount of microorganisms for water treatment.
[0173]
Further, according to the invention of claim 8, the control device of the oxidation ditch water treatment device is configured to extract the sludge according to the means for measuring the quality of the treated water and the deviation between the measured value of the water quality and a predetermined target value. Since the controller for calculating the target value of the amount and the means for adjusting the amount of sludge extraction according to the target value of the sludge extraction amount are provided, the aerobic region and the anaerobic region are appropriately formed in the ditch. There is an effect that an excess or deficiency in the amount of microorganisms for water treatment does not occur.
[0174]
Claims9According to the invention, the control device of the oxidation ditch water treatment apparatus is configured to measure the inflow load into the ditch and the feedforward amount of the reference value of the rotation speed of the aeration rotor or the immersion depth from the measured value of the inflow load. And a means for calculating, so that the effect of being able to maintain a good quality of treated water more stably.is there.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a tank row model used in a computer simulation for finding the first to fourth laws according to the present invention.
FIG. 2 is a graph showing the results of a computer simulation with the MLSS concentration set to 3000 [mg / L] and the aeration rotor immersion depth set to 15 [cm].
FIG. 3 is a graph showing the results of computer simulation with the MLSS concentration set to 3000 [mg / L] and the aeration rotor immersion depth set to 20 [cm].
FIG. 4 is a graph showing the results of computer simulation with the MLSS concentration set to 3000 [mg / L] and the aeration rotor immersion depth set to 24 [cm].
FIG. 5 is a graph showing the results of computer simulation with the MLSS concentration set to 4000 [mg / L] and the aeration rotor immersion depth set to 15 [cm].
FIG. 6 is a graph showing the results of computer simulation with the MLSS concentration set to 4000 [mg / L] and the aeration rotor immersion depth set to 20 [cm].
FIG. 7 is a graph showing the results of computer simulation with the MLSS concentration set to 4000 [mg / L] and the aeration rotor immersion depth set to 24 [cm].
FIG. 8 is a graph showing the results of computer simulation with the MLSS concentration set to 5000 [mg / L] and the aeration rotor immersion depth set to 15 [cm].
FIG. 9 is a graph showing the results of computer simulation with the MLSS concentration set to 5000 [mg / L] and the aeration rotor immersion depth set to 20 [cm].
FIG. 10 is a graph showing the results of computer simulation with the MLSS concentration set at 5000 [mg / L] and the aeration rotor immersion depth set at 24 [cm].
FIG. 11 is a graph showing the relationship between the difference between nitrate nitrogen concentration and ammonia nitrogen concentration at point F and the total nitrogen concentration.
FIG. 12 is a graph showing the results of computer simulation with the nitrification rate set to 10 times.
FIG. 13 is a graph showing the results of computer simulation with the nitrification rate set to 10 times.
FIG. 14 is a graph showing the results of computer simulation with the nitrification rate set to 10 times.
FIG. 15 is a graph showing the results of computer simulation with the denitrification rate set to 10 times.
FIG. 16 is a graph showing the results of computer simulation with the denitrification rate set to 10 times.
FIG. 17 is a graph showing the results of a computer simulation with the denitrification rate set to 10 times.
FIG. 18 is a graph showing the relationship between the dissolved oxygen concentration at point A and the total nitrogen concentration at point F.
FIG. 19 shows the present invention.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by 1. FIG.
FIG. 20 shows the present invention.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by 2. FIG.
FIG. 21 shows the present invention.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by 4. FIG.
FIG. 22 shows the present invention.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by 5. FIG.
FIG. 23 shows the present invention.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by 7. FIG.
FIG. 24 shows the present invention.Reference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by 8. FIG.
FIG. 25 shows the present invention.Reference example10 is a configuration diagram showing a control device of an oxidation ditch water treatment device according to FIG.
FIG. 26 of the present inventionReference exampleIt is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by 11.
FIG. 27 shows an example of the present invention.1It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 28 shows an example of the present invention.2It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 29 shows an example of the present invention.3It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 30 shows an example of the present invention.4It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 31 shows an example of the present invention.5It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 32 shows an example of the present invention.7It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 33 shows an example of the present invention.9It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 34 shows an example of the present invention.11It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 35 shows an example of the present invention.11It is a graph which shows the relationship between MLSS density | concentration memorize | stored in the memory circuit 26 of the control apparatus of the oxidation ditch water treatment apparatus by and total nitrogen density | concentration.
FIG. 36 shows an example of the present invention.12It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 37 shows an example of the present invention.14It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 38 shows an example of the present invention.16It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 39 shows an example of the present invention.22It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 40 shows an example of the present invention.24It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 41 shows an example of the present invention.28It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 42 of the present inventionReference Example 13It is a block diagram which shows the control apparatus of the oxidation ditch water treatment apparatus by A.
FIG. 43 is a configuration diagram showing a conventional oxidation ditch water treatment apparatus.
[Explanation of symbols]
1 ditch
2 Aeration rotor
3 Drive unit
4 Overflow cough
5 Settling pond
6 Pump
8, 18 Dissolved oxygen concentration meter
9, 11, 16, 20, 28, 30, 38, 102, 104, 107, 108, 110, 111, 113 Controller
10, 15, 17, 23, 27, 33, 103, 106, 109, 112 Setter
12, 14, 19, 22, 24, 29, 32, 34, 36
13 Drive device
21 Microbial concentration meter
25 Total nitrogen concentration meter
26 Memory circuit
31 Thermometer
35, 37 Flow meter
100 Nitrate nitrogen concentration meter
101 Ammonia nitrogen concentration meter

Claims (9)

Flowing water to be treated into the ditch, performs activated sludge treatment by mechanical aeration device provided in the ditch, the control device of the oxidation ditch water treatment apparatus that removes the nitrogen components of the water to be treated, the aeration Means for measuring the dissolved oxygen concentration at an arbitrary point in a region that is 1/4 to 1/2 times as long as the ditch length in the flow direction from the installation point in the ditch of the apparatus ; the measured value of the dissolved oxygen concentration; to 1 in accordance with the deviation between a preset target value of the dissolved oxygen concentration to a value of [mg / l], and the treatment water outlet point in installation point and the ditch within the ditch of the aeration device According to the controller that outputs the target value of the rotational speed or immersion depth of the aeration apparatus, and the target value of the rotational speed or immersion depth so that the boundary between the aerobic region and the anaerobic region is near the center of ,Up Controller of oxidation ditch water treatment apparatus characterized by comprising adjustment means for adjusting the rotational speed or the immersion depth of the aerator. Flowing water to be treated into the ditch, performs activated sludge treatment by mechanical aeration device provided in the ditch, the control device of the oxidation ditch water treatment apparatus for removing nitrogen components of the water to be treated, the aeration At least one or more dissolved oxygen concentration measuring means installed in the range of 0 to 1/2 times the ditch length in the flow direction from the installation point in the above-mentioned ditch of the apparatus, measured by this dissolved oxygen concentration measuring means An arithmetic means for calculating a point at which the dissolved oxygen concentration in the ditch reaches a reference value of the dissolved oxygen concentration set in advance to a value in the vicinity of 0 [mg / liter] using the measured value of the dissolved oxygen concentration. and the values calculated, is preset in the vicinity of the center of the water to be treated flow out point in installation point and the ditch within the ditch of the aeration device, reaches the reference value Depending on the deviation between the target value of the point, as the boundary between the central area in the aerobic region and the anaerobic region of the treated water outflow point in installation point and the ditch within the ditch of the aerator coming A controller for outputting a target value of the rotation speed or immersion depth of the aeration apparatus, and an adjusting means for adjusting the rotation speed or immersion depth of the aeration apparatus according to the target value of the rotation speed or immersion depth. The control apparatus of the oxidation ditch water treatment apparatus characterized by having provided.   The correction means which correct | amends the target value of dissolved oxygen concentration from the measured value of the density | concentration of the activated sludge microorganisms measured in the arbitrary points in a ditch, or the target value of activated sludge microorganisms concentration is provided. The control apparatus of the oxidation ditch water treatment apparatus of description.   A correction means is provided for correcting the target value of the point where the dissolved oxygen concentration reaches the reference value from the measured value of the activated sludge microbial concentration measured at any point in the ditch or the target value of the activated sludge microbial concentration. The control apparatus of the oxidation ditch water treatment apparatus according to claim 2.   It is characterized by comprising means for measuring at least one of water temperature, pH and oxidation-reduction potential installed at any point in the ditch, and correction means for correcting the target value of dissolved oxygen concentration from these measured values. The control apparatus of the oxidation ditch water treatment apparatus according to claim 1 or 3.   Means for measuring at least one of water temperature, pH, oxidation-reduction potential installed at any point in the ditch, and correction means for correcting the target value at the point that reaches the reference value of dissolved oxygen concentration from these measured values The control apparatus of the oxidation ditch water treatment apparatus according to claim 2 or 4, wherein the control apparatus is provided.   Means to measure the concentration of activated sludge microorganisms installed at any point in the ditch, means to measure the quality of treated water, activated sludge according to the deviation between the measured value of water quality and a predetermined target value of water quality An arithmetic unit that calculates a target value of the microorganism concentration, a controller that outputs a target value of the sludge extraction amount according to a deviation between the target value of the activated sludge microorganism concentration and the measured value of the activated sludge microorganism concentration, and the sludge extraction The control device for an oxidation ditch water treatment apparatus according to any one of claims 1 to 6, further comprising adjusting means for adjusting the amount of sludge extraction according to a target value of the amount.   Means for measuring the quality of the treated water, a controller for calculating the target value of the sludge extraction amount according to the deviation between the measured value of the water quality and the predetermined target value of the water quality, sludge according to the target value of the sludge extraction amount The control device for an oxidation ditch water treatment device according to any one of claims 1 to 7, further comprising adjusting means for adjusting a drawing amount.   9. A means for measuring an inflow load into the ditch, and a means for calculating a feedforward amount of a reference value of the rotational speed or immersion depth of the aeration apparatus from a measured value of the inflow load. The control apparatus of the oxidation ditch water treatment apparatus in any one of.

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