JP5802426B2 - Biological water treatment equipment - Google Patents

Biological water treatment equipment Download PDF

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JP5802426B2
JP5802426B2 JP2011097947A JP2011097947A JP5802426B2 JP 5802426 B2 JP5802426 B2 JP 5802426B2 JP 2011097947 A JP2011097947 A JP 2011097947A JP 2011097947 A JP2011097947 A JP 2011097947A JP 5802426 B2 JP5802426 B2 JP 5802426B2
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aeration
nitrification rate
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nitrous oxide
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卓矢 上門
卓矢 上門
一郎 山野井
一郎 山野井
伊智朗 圓佛
伊智朗 圓佛
剛 武本
剛 武本
田所　秀之
秀之 田所
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Hitachi Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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    • Y02W10/10—Biological treatment of water, waste water, or sewage

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  • Activated Sludge Processes (AREA)

Description

本発明は、下水などの被処理水を浄化する水処理装置に係り、特に、酸素が溶存している好気性環境に置かれた活性汚泥と呼ばれる微生物のはたらきにより、被処理水中のアンモニア性窒素を硝酸性窒素に生物学的に分解する生物学的水処理装置に関する。   The present invention relates to a water treatment apparatus for purifying treated water such as sewage, and in particular, ammonia nitrogen in the treated water due to the action of microorganisms called activated sludge placed in an aerobic environment in which oxygen is dissolved. The present invention relates to a biological water treatment apparatus that biologically decomposes water into nitrate nitrogen.

下水などの被処理水を浄化するために水処理装置が用いられる。かかる水処理装置の例として、酸素が溶存している好気性環境に置かれた活性汚泥と呼ばれる微生物のはたらきにより、被処理水中のアンモニア性窒素を硝酸性窒素に生物学的に分解する生物学的水処理装置が知られている。こうした生物学的水処理装置では、被処理水中に含まれる窒素成分は、アンモニア性窒素（ＮＨ4 −Ｎ）を硝酸性窒素（ＮＯ3 −Ｎ）に酸化する硝化反応と、硝酸性窒素を窒素ガスに還元する脱窒反応とにより除去される。 A water treatment device is used to purify treated water such as sewage. As an example of such a water treatment device, biology of biologically degrading ammonia nitrogen in treated water into nitrate nitrogen by the action of microorganisms called activated sludge placed in an aerobic environment in which oxygen is dissolved Automatic water treatment equipment is known. In such a biological water treatment apparatus, nitrogen components contained in the water to be treated include a nitrification reaction that oxidizes ammoniacal nitrogen (NH 4 -N) to nitrate nitrogen (NO 3 -N), and nitrate nitrogen as nitrogen. It is removed by a denitrification reaction that reduces to gas.

被処理水を浄化する過程で起こる硝化反応では、副生成物として亜酸化窒素（N2O）が生じることが知られている。最近、亜酸化窒素（N2O）と、温室効果との因果関係が明らかになっている。亜酸化窒素（N2O）は、二酸化炭素（CO2）に比べておよそ３００倍の温室効果を有する。このため、亜酸化窒素（N2O）は、地球温暖化を助長する物質として、その排出量の削減が求められている。 It is known that nitrous oxide (N 2 O) is generated as a by-product in the nitrification reaction that occurs in the process of purifying treated water. Recently, a causal relationship between nitrous oxide (N 2 O) and the greenhouse effect has been clarified. Nitrous oxide (N 2 O) has a greenhouse effect approximately 300 times that of carbon dioxide (CO 2 ). For this reason, nitrous oxide (N 2 O) is required to reduce emissions as a substance that promotes global warming.

被処理水の浄化過程で生じる亜酸化窒素（N2O）が大気中へ拡散されることを抑制するために、特許文献１には、硝化反応に伴って生じる亜酸化窒素（N2O）の濃度をN2O計により測定し、その測定結果に基づき、生物反応槽の曝気量を制御する亜酸化窒素抑制方法が記載されている。 In order to suppress diffusion of nitrous oxide (N 2 O) generated in the purification process of treated water into the atmosphere, Patent Document 1 discloses nitrous oxide (N 2 O) generated in association with nitrification reaction. A nitrous oxide suppression method is described in which the concentration of NO is measured with a N 2 O meter, and the amount of aeration in the biological reaction tank is controlled based on the measurement result.

特開２０１０−９４６６５号公報JP 2010-94665 A

しかしながら、特許文献１に係る亜酸化窒素抑制技術では、被処理水の水質悪化を招くおそれがあった。その理由は以下の通りである。すなわち、特許文献１に係る亜酸化窒素抑制技術では、亜酸化窒素（N2O）の濃度が高い場合は曝気量を減少させる制御が行われる。曝気量を減少させると亜酸化窒素（N2O）の濃度を低く抑えることができるからである。このように曝気量を減少させる制御が行われると、硝化反応の進行が抑制される。硝化反応は酸化により促進される化学反応だからである。こうして硝化反応の進行が抑制されると、被処理水中のアンモニア性窒素はなかなか減らない。その結果、特許文献１に係る亜酸化窒素抑制技術では、被処理水の水質悪化を招くおそれがあった。 However, in the nitrous oxide suppression technology according to Patent Document 1, there is a possibility that the quality of water to be treated is deteriorated. The reason is as follows. That is, in the nitrous oxide suppression technique according to Patent Document 1, when the concentration of nitrous oxide (N 2 O) is high, control for reducing the amount of aeration is performed. This is because the concentration of nitrous oxide (N 2 O) can be kept low by reducing the amount of aeration. When the control for reducing the amount of aeration is performed in this way, the progress of the nitrification reaction is suppressed. This is because the nitrification reaction is a chemical reaction promoted by oxidation. When the progress of the nitrification reaction is suppressed in this way, ammonia nitrogen in the water to be treated is not easily reduced. As a result, the nitrous oxide suppression technology according to Patent Document 1 may cause deterioration of the quality of water to be treated.

本発明は、上記実情に鑑みてなされたものであり、被処理水の水質の維持と亜酸化窒素（N2O）の生成量の抑制を両立可能な生物学的水処理装置を提供することを目的とする。 The present invention has been made in view of the above circumstances, and provides a biological water treatment apparatus capable of both maintaining the quality of treated water and suppressing the amount of nitrous oxide (N 2 O) produced. With the goal.

本発明に係る生物学的水処理装置は、酸素が溶存している好気性環境に置かれた活性汚泥のはたらきにより、被処理水中のアンモニア性窒素（ＮＨ4 −Ｎ）を硝酸性窒素（ＮＯ3 −Ｎ）に生物学的に分解する生物学的水処理装置であって、前記被処理水と共に前記活性汚泥が溜められた生物反応槽と、前記生物反応槽内において曝気を行う曝気部と、前記生物反応槽内の亜酸化窒素（N2O）の量の相関値を、前記生物反応槽内に設けられた酸化還元電位計の検出値に基づき取得するN2O量相関値取得部と、前記生物反応槽内で起こる硝化反応の進行程度を表す硝化率の目標として予め設定された目標硝化率を記憶する目標硝化率記憶部と、前記生物反応槽内の亜酸化窒素（N2O）の量の相関値に対応する、前記目標硝化率に係る適正補正量の関係を記憶する硝化率補正量記憶部と、前記曝気部の曝気量を制御する曝気量制御部と、を備える。
前記曝気量制御部は、前記N2O量相関値取得部で取得された前記亜酸化窒素（N2O）の量の相関値と、前記硝化率補正量記憶部の記憶内容とに基づいて、前記亜酸化窒素（N2O）の量の相関値に対応する前記目標硝化率に係る適正補正量を求めると共に、この目標硝化率に係る適正補正量を用いて補正した前記目標硝化率を制御目標として前記曝気部の曝気量を制御する、ことを要旨とする。 The biological water treatment apparatus according to the present invention converts ammonia nitrogen (NH 4 -N) in water to be treated into nitrate nitrogen (NO) by the action of activated sludge placed in an aerobic environment in which oxygen is dissolved. 3- N) a biological water treatment apparatus that biologically decomposes, a biological reaction tank in which the activated sludge is stored together with the water to be treated, and an aeration unit that performs aeration in the biological reaction tank; The N 2 O amount correlation value acquisition unit acquires the correlation value of the amount of nitrous oxide (N 2 O) in the biological reaction tank based on the detection value of the oxidation-reduction potentiometer provided in the biological reaction tank A target nitrification rate storage unit that stores a target nitrification rate that is set in advance as a nitrification rate target that represents the degree of progress of the nitrification reaction that occurs in the biological reaction tank; and nitrous oxide (N 2 in the biological reaction tank) corresponding to the correlation value of the amount of O), appropriate correction amount related according to the target nitrification rate Comprising a nitrification rate correction amount storage unit that stores, and aeration amount control section for controlling the aeration amount of the aeration unit, the a.
The aeration amount control unit is based on the correlation value of the nitrous oxide (N 2 O) amount acquired by the N 2 O amount correlation value acquisition unit and the storage content of the nitrification rate correction amount storage unit. And obtaining an appropriate correction amount related to the target nitrification rate corresponding to the correlation value of the amount of nitrous oxide (N 2 O), and correcting the target nitrification rate using the appropriate correction amount related to the target nitrification rate. The gist is to control the aeration amount of the aeration unit as a control target.

本発明によれば、被処理水の水質の維持と亜酸化窒素（N2O）の生成量の抑制を両立可能な生物学的水処理装置を提供することができる。 According to the present invention can provide a compatible possible biological water treatment apparatus the amount of inhibition of maintaining and nitrous oxide in water quality of the water to be treated (N 2 O).

本発明の第１実施形態に係る第１の生物学的水処理装置の機能ブロック図である。It is a functional block diagram of the 1st biological water treatment equipment concerning a 1st embodiment of the present invention. 生物反応槽内で硝化反応が進行してゆく過程における酸化還元電位（ＯＲＰ）に対する亜酸化窒素（N2O）の生成量特性を表す図である。Is a diagram illustrating a sub-generation amount characteristic of oxide (N 2 O) for the oxidation-reduction potential (ORP) in the process of slide into proceeds nitrification in bioreactor tank. 本発明の第１実施形態に係る第１の生物学的水処理装置の動作説明に供するフローチャート図である。It is a flowchart figure with which it uses for operation | movement description of the 1st biological water treatment apparatus which concerns on 1st Embodiment of this invention. 本発明の第２実施形態に係る第２の生物学的水処理装置の機能ブロック図である。It is a functional block diagram of the 2nd biological water treatment apparatus concerning a 2nd embodiment of the present invention. 生物反応槽内で硝化反応が進行してゆく過程における酸化還元電位（ＯＲＰ）に対する硝化率特性を表す図である。It is a figure showing the nitrification rate characteristic with respect to oxidation-reduction potential (ORP) in the process in which nitrification reaction advances in a biological reaction tank. 本発明の第２実施形態に係る第２の生物学的水処理装置の動作説明に供するフローチャート図である。It is a flowchart figure with which it uses for operation | movement description of the 2nd biological water treatment apparatus which concerns on 2nd Embodiment of this invention. 本発明の第３実施形態に係る第３の生物学的水処理装置の機能ブロック図である。It is a functional block diagram of the 3rd biological water treatment equipment concerning a 3rd embodiment of the present invention. 本発明の第３実施形態に係る第３の生物学的水処理装置の動作説明に供するフローチャート図である。It is a flowchart figure with which it uses for operation | movement description of the 3rd biological water treatment apparatus which concerns on 3rd Embodiment of this invention.

以下、本発明の複数の実施形態について、図面を参照しながら詳細に説明する。
［第１実施形態］
（第１の生物学的水処理装置１１の構成）
図１は、本発明の第１実施形態に係る第１の生物学的水処理装置１１の機能ブロック図である。図２は、生物反応槽１３内で硝化反応が進行してゆく過程における酸化還元電位（ＯＲＰ：Oxidation-reduction Potential）に対する亜酸化窒素（N2O）の生成量特性を表す図である。本発明の第１実施形態に係る第１の生物学的水処理装置１１は、図１に示すように、被処理水Ｗと共に活性汚泥（不図示）が溜められた生物反応槽１３と、散気部１５と、送気用ブロワ１７と、酸化還元電位計１９と、N2O量相関値取得部２１と、曝気量補正量記憶部２３と、第１の曝気量制御部２５と、を備えて構成されている。 Hereinafter, a plurality of embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
(Configuration of the first biological water treatment apparatus 11)
FIG. 1 is a functional block diagram of a first biological water treatment apparatus 11 according to the first embodiment of the present invention. FIG. 2 is a diagram showing the production amount characteristics of nitrous oxide (N 2 O) with respect to an oxidation-reduction potential (ORP) in the process in which the nitrification reaction proceeds in the biological reaction tank 13. As shown in FIG. 1, the first biological water treatment apparatus 11 according to the first embodiment of the present invention includes a biological reaction tank 13 in which activated sludge (not shown) is stored together with water to be treated W, An air unit 15, an air supply blower 17, an oxidation-reduction potentiometer 19, an N 2 O amount correlation value acquisition unit 21, an aeration amount correction amount storage unit 23, and a first aeration amount control unit 25. It is prepared for.

活性汚泥は、微生物の凝集した粒径０.１〜１.０ｍｍ前後の塊（フロック）であり、数十種類の微生物を含む。活性汚泥は、一般に、被処理水Ｗ中に浮遊した状態で存在する。第１の生物学的水処理装置１１は、酸素が溶存している好気性環境に置かれた活性汚泥のはたらきにより、被処理水Ｗ中のアンモニア性窒素（ＮＨ4 −Ｎ）を硝酸性窒素（ＮＯ3 −Ｎ）に生物学的に酸化分解する。こうした窒素形態の変化を硝化反応と呼ぶ。 The activated sludge is a mass (floc) having a particle size of about 0.1 to 1.0 mm in which microorganisms are aggregated, and includes several tens of kinds of microorganisms. Generally activated sludge exists in the state which floated in the to-be-processed water W. FIG. The first biological water treatment device 11 converts ammonia nitrogen (NH 4 -N) in the water to be treated W into nitrate nitrogen by the action of activated sludge placed in an aerobic environment in which oxygen is dissolved. (NO 3 -N) to decompose biologically oxidized. Such a change in nitrogen form is called a nitrification reaction.

生物反応槽１３の上流側には、不図示の最初沈殿池が設けられている。最初沈殿池では、家庭や工場等から排出された下水が流入し、ゴミや砂などの比較的大きい異物が沈降除去される。最初沈殿池において異物が除去された一次処理水は、所定の流速をもって、定常的または間欠的に、生物反応槽１３へと流入する。生物反応槽１３では、前記した硝化反応の他に、硝酸性窒素（ＮＯ3 −Ｎ）を窒素ガスに還元する脱窒反応が行われる。ただし、この脱窒反応は、生物反応槽１３のうち嫌気槽（不図示）において行われる。 A first sedimentation tank (not shown) is provided on the upstream side of the biological reaction tank 13. In the first sedimentation basin, sewage discharged from a home or factory flows in, and relatively large foreign matters such as dust and sand are settled and removed. The primary treated water from which foreign substances have been removed in the initial sedimentation basin flows into the biological reaction tank 13 at a predetermined flow rate, either constantly or intermittently. In the biological reaction tank 13, in addition to the nitrification reaction described above, a denitrification reaction that reduces nitrate nitrogen (NO 3 —N) to nitrogen gas is performed. However, this denitrification reaction is performed in an anaerobic tank (not shown) in the biological reaction tank 13.

生物反応槽１３の下流側には、不図示の最終沈殿池が設けられている。最終沈殿池には、下水および活性汚泥が混合された二次処理水が、オーバーフロー式に生物反応槽１３から流出する。最終沈殿池では、活性汚泥が重力によって沈降する。図示していないが，活性汚泥の一部は生物反応槽１３に返送汚泥として戻される。最終沈殿池の上澄み液は、通常、塩素やオゾン等による殺菌処理が施された後に、河川や海などに放流される。   A final sedimentation tank (not shown) is provided on the downstream side of the biological reaction tank 13. In the final sedimentation basin, secondary treated water mixed with sewage and activated sludge flows out from the biological reaction tank 13 in an overflow manner. In the final sedimentation basin, activated sludge settles by gravity. Although not shown, a part of the activated sludge is returned to the biological reaction tank 13 as return sludge. The supernatant liquid of the final sedimentation basin is usually discharged into rivers or the sea after being sterilized by chlorine, ozone, or the like.

生物反応槽１３の底部には、図１に示すように、散気部１５が設けられている。散気部１５は、空気導管１６を介して送気用ブロワ１７に連通接続されている。送気用ブロワ１７によって空気導管１６を介して送られた空気は、散気管１５に設けられた不図示の小孔を介して微少な気泡の粒の状態で散気されるようになっている。これにより、生物反応槽１３内の下水および活性汚泥からなる混合液には、撹拌および酸素の供給がなされる。こうして供給された酸素は、生物反応槽１３を好気性環境にするのに役立つ。なお、散気部１５および送気用ブロワ１７は、本発明の“曝気部”として機能する。   As shown in FIG. 1, an air diffuser 15 is provided at the bottom of the biological reaction tank 13. The air diffuser 15 is connected to an air blower 17 through an air conduit 16. The air sent by the air blower 17 through the air conduit 16 is diffused in the form of fine bubbles through a small hole (not shown) provided in the air diffuser 15. . As a result, the mixed liquid composed of the sewage and activated sludge in the biological reaction tank 13 is stirred and supplied with oxygen. The oxygen supplied in this way serves to make the biological reaction tank 13 an aerobic environment. The air diffuser 15 and the air blower 17 function as the “aeration unit” of the present invention.

生物反応槽１３内に一時的に溜められた被処理水Ｗには、図１に示すように、酸化還元電位（以下、“ＯＲＰ”と省略する。）を計測するＯＲＰ計１９のプローブ１９ａが浸漬されている。生物反応槽１３内におけるプローブ１９ａの設置位置は、被処理水Ｗの流通経路のうち下流側が好ましい。被処理水Ｗの流通経路のうち下流側では、その上流側と比べて、硝化反応の進行状況をよく反映した計測値が得られるからである。   The treated water W temporarily stored in the biological reaction tank 13 has a probe 19a of an ORP meter 19 for measuring an oxidation-reduction potential (hereinafter abbreviated as “ORP”) as shown in FIG. Soaked. The installation position of the probe 19a in the biological reaction tank 13 is preferably on the downstream side in the flow path of the water to be treated W. This is because, on the downstream side of the flow path of the water to be treated W, measurement values that better reflect the progress of the nitrification reaction can be obtained compared to the upstream side.

ＯＲＰ計１９によって計測されたＯＲＰ検出値は、第１の生物学的水処理装置１１において、亜酸化窒素（N2O）の相関値として取り扱うことができる。その理由は、図２に示すように、生物反応槽１３内で硝化反応が進行している場合において、ＯＲＰ検出値と、亜酸化窒素（N2O）の量とは、所定の相関関係があるからである。なお、ＯＲＰ計１９によって計測されたＯＲＰ検出値は、被処理水Ｗの温度変化に応じた補正後の値を採用するのが好ましい。ＯＲＰ検出値は、被処理水Ｗの温度変化に応じた誤差を生じるからである。 The ORP detection value measured by the ORP meter 19 can be handled as a correlation value of nitrous oxide (N 2 O) in the first biological water treatment apparatus 11. The reason for this is that, as shown in FIG. 2, when a nitrification reaction is proceeding in the biological reaction tank 13, the ORP detection value and the amount of nitrous oxide (N 2 O) have a predetermined correlation. Because there is. In addition, it is preferable to employ | adopt the value after correction | amendment according to the temperature change of the to-be-processed water W as the ORP detection value measured by the ORP meter 19. FIG. This is because the ORP detection value causes an error according to the temperature change of the water to be treated W.

第１の生物学的水処理装置１１において亜酸化窒素（N2O）の相関値として取り扱われるＯＲＰ検出値は、図１に示すように、N2O量相関値取得部２１に与えられる。N2O量相関値取得部２１は、生物反応槽１３内の亜酸化窒素（N2O）の量の相関値を取得する機能を有する。具体的には、例えば、N2O量相関値取得部２１は、ＯＲＰ検出値そのものを亜酸化窒素（N2O）の量として取り扱ってもよいし、ＯＲＰ値とN2O量との対照表を用いて、ＯＲＰ検出値をN2O量に換算した値として取り扱ってもよい。また、ＯＲＰ値をN2O量に換算するための関係式を用いて、ＯＲＰ検出値をN2O量に換算した値として取り扱ってもよい。 The ORP detection value handled as the correlation value of nitrous oxide (N 2 O) in the first biological water treatment apparatus 11 is given to the N 2 O amount correlation value acquisition unit 21 as shown in FIG. The N 2 O amount correlation value acquisition unit 21 has a function of acquiring a correlation value of the amount of nitrous oxide (N 2 O) in the biological reaction tank 13. Specifically, for example, the N 2 O amount correlation value acquisition unit 21 may treat the ORP detection value itself as the amount of nitrous oxide (N 2 O), or contrast the ORP value with the N 2 O amount. Using the table, the ORP detection value may be handled as a value converted to the N 2 O amount. Further, by using a relational expression for converting the ORP value in the N 2 O content, the ORP detected value may be handled as a value in terms of N 2 O quantity.

曝気量補正量記憶部２３は、次の（表１）に示すように、単位時間あたりのN2O生成量に対する適正な曝気量補正量に係る第１の関係表を記憶している。この第１の関係表では、単位時間あたりのN2O生成量［ｇ／ｈ］を５段階に分けて、各段階毎に、相互に異なる適正な曝気量補正量［％］をそれぞれ対応づけて記述している。すなわち、第１の関係表には、N2O生成量：（１０＞）［ｇ／ｈ］に対して曝気量補正量：５［％］が、N2O生成量：（１０〜２０）［ｇ／ｈ］に対して曝気量補正量：２［％］が、N2O生成量：（２０〜３０）［ｇ／ｈ］に対して曝気量補正量：０［％］が、N2O生成量：（３０〜５０）［ｇ／ｈ］に対して曝気量補正量：−２［％］が、N2O生成量：（５０＜）［ｇ／ｈ］に対して曝気量補正量：−５［％］が、それぞれ対応づけて記述されている。

Figure 0005802426
As shown in the following (Table 1), the aeration amount correction amount storage unit 23 stores a first relational table related to an appropriate aeration amount correction amount with respect to the N 2 O generation amount per unit time. In this first relational table, the N 2 O production amount [g / h] per unit time is divided into five stages, and different appropriate aeration amount correction amounts [%] are associated with each stage. Is described. That is, in the first relational table, the aeration amount correction amount: 5 [%] with respect to the N 2 O production amount: (10>) [g / h], but the N 2 O production amount: (10-20) Aeration amount correction amount: 2 [%] with respect to [g / h], aeration amount correction amount: 0 [%] with respect to N 2 O generation amount: (20-30) [g / h], N Aeration amount correction amount: −2 [%] with respect to 2 O production amount: (30-50) [g / h], but aeration amount with respect to N 2 O production amount: (50 <) [g / h] Correction amount: −5 [%] is described in association with each other.
Figure 0005802426

要するに、第１の関係表では、N2O生成量が少ない場合は、硝化反応の促進が足りないものとみなして曝気量を増大させる補正を行い、N2O生成量が多い場合は、硝化反応の促進が過剰になされているものとみなして曝気量を減少させる補正を行い、N2O生成量が適正な場合は、硝化反応の促進が適切になされているものとみなして曝気量をそのまま維持させる（補正なし）といったように、第１の曝気量制御部２５が制御対象とする曝気量を、N2O生成量の多少に応じて補正させることを狙っている。 In short, in the first relational table, when the amount of N 2 O produced is small, it is assumed that the nitrification reaction is not accelerated, and the amount of aeration is increased. When the amount of N 2 O produced is large, nitrification is performed. A correction is made to reduce the amount of aeration assuming that the reaction is promoted excessively.If the amount of N 2 O produced is appropriate, the nitrification reaction is considered to be promoted appropriately and the amount of aeration is reduced. The aim is to correct the aeration amount to be controlled by the first aeration amount control unit 25 according to the amount of N 2 O generation so that it is maintained as it is (without correction).

第１の曝気量制御部２５は、曝気量補正量演算部２７を備える。曝気量補正量演算部２７は、N2O量相関値取得部２１で取得された亜酸化窒素（N2O）の量の相関値と、曝気量補正量記憶部２３の記憶内容とに基づいて、亜酸化窒素（N2O）の量の相関値に対応する曝気部１５，１７の曝気量に係る適正補正量を求める。第１の曝気量制御部２５は、この曝気量に係る適正補正量を用いて補正した曝気量を制御目標として、曝気部（散気部１５および送気用ブロワ１７；以下では、“曝気部１５，１７”と省略する。）の曝気量を制御するように動作する。 The first aeration amount control unit 25 includes an aeration amount correction amount calculation unit 27. The aeration amount correction amount calculation unit 27 is based on the correlation value of the amount of nitrous oxide (N 2 O) acquired by the N 2 O amount correlation value acquisition unit 21 and the stored contents of the aeration amount correction amount storage unit 23. Thus, an appropriate correction amount related to the aeration amount of the aeration units 15 and 17 corresponding to the correlation value of the amount of nitrous oxide (N 2 O) is obtained. The first aeration amount control unit 25 uses the aeration amount corrected by using the appropriate correction amount related to the aeration amount as a control target, and uses the aeration unit (aeration unit 15 and air supply blower 17; hereinafter, “aeration unit”). The aeration amount is abbreviated as 15, 17 ″.

（本発明の第１実施形態に係る第１の生物学的水処理装置１１の動作）
次に、本発明の第１実施形態に係る第１の生物学的水処理装置１１の動作について、図面を参照して説明する。図３は、本発明の第１実施形態に係る第１の生物学的水処理装置１１の動作説明に供するフローチャート図である。 (Operation of the first biological water treatment apparatus 11 according to the first embodiment of the present invention)
Next, operation | movement of the 1st biological water treatment apparatus 11 which concerns on 1st Embodiment of this invention is demonstrated with reference to drawings. FIG. 3 is a flowchart for explaining the operation of the first biological water treatment apparatus 11 according to the first embodiment of the present invention.

第１の生物学的水処理装置１１の動作説明に先立って、本発明において前提となる事実関係を明らかにしておく。下水処理における亜酸化窒素（N2O）の生成条件の一つに硝化反応の進行が挙げられる。生物反応槽１３内の被処理水Ｗ中に含まれるアンモニア性窒素（ＮＨ4 −Ｎ）は、活性汚泥のはたらきによる硝化反応によって、亜硝酸性窒素（ＮＯ2 −Ｎ）を経て硝酸性窒素（ＮＯ3 −Ｎ）に酸化される。亜酸化窒素（N2O）は、硝化反応の副生成物として生成される。硝化反応は酸化反応である。このため、酸素の供給量を制御すれば、その反応量（亜酸化窒素（N2O）の生成量）を制御することができる。 Prior to the description of the operation of the first biological water treatment apparatus 11, the factual relationship which is a premise in the present invention will be clarified. One of the conditions for producing nitrous oxide (N 2 O) in sewage treatment is the progress of nitrification reaction. Ammonia nitrogen (NH 4 -N) contained in the water to be treated W in the biological reaction tank 13 is converted to nitrate nitrogen (NO 2 -N) through nitrite nitrogen (NO 2 -N) by the nitrification reaction by the action of activated sludge. is oxidized to NO 3 -N). Nitrous oxide (N 2 O) is produced as a byproduct of the nitrification reaction. The nitrification reaction is an oxidation reaction. For this reason, if the supply amount of oxygen is controlled, the reaction amount (the amount of nitrous oxide (N 2 O) produced) can be controlled.

具体的には、曝気量を増加させると酸素の供給量は増加し、硝化反応の進行が促進される。この場合、硝化反応の副生成物である亜酸化窒素（N2O）の生成量は増加する。一方、曝気量を減少させると酸素の供給量は減少し、硝化反応の進行が抑制される。この場合、硝化反応の副生成物である亜酸化窒素（N2O）の生成量は減少する。本第１実施形態では、こうした曝気量と亜酸化窒素（N2O）の生成量との因果関係を利用することによって、被処理水Ｗの水質の維持と亜酸化窒素（N2O）の生成量抑制との両立を図っている。 Specifically, when the aeration amount is increased, the supply amount of oxygen is increased, and the progress of the nitrification reaction is promoted. In this case, the amount of nitrous oxide (N 2 O) that is a byproduct of the nitrification reaction increases. On the other hand, when the amount of aeration is reduced, the supply amount of oxygen is reduced and the progress of the nitrification reaction is suppressed. In this case, the amount of nitrous oxide (N 2 O) that is a byproduct of the nitrification reaction is reduced. In the first embodiment, by utilizing a causal relationship between the amount of such aeration amount and nitrous oxide (N 2 O), maintained and nitrous oxide in water quality of the water to be treated W of (N 2 O) It aims at coexistence with production amount control.

なお、本第１実施形態に係る第１の生物学的水処理装置１１では、次に述べるように、基準となる曝気量を予め設定しておき、設定された曝気量を、亜酸化窒素（N2O）の量に応じて段階的に補正するように動作する。ここで、基準となる曝気量を設定するにあたっては、いくつかの方式がある。すなわち、曝気量を所定の固定値に設定する曝気量固定制御方式と、被処理水Ｗの流量に比例して曝気量を可変制御する流量比例制御方式と、生物反応槽１３内の溶存酸素（ＤＯ）を一定に維持するように曝気量を制御するＤＯ一定制御方式と、がそれである。次に述べる動作説明では、前記したいずれかの方式により決定された曝気量に対して、亜酸化窒素（N2O）の量に応じた補正が行われるものとする。 In the first biological water treatment apparatus 11 according to the first embodiment, as described below, a reference aeration amount is set in advance, and the set aeration amount is converted to nitrous oxide ( N 2 O) operates so as to be corrected step by step according to the amount. Here, there are several methods for setting a reference aeration amount. That is, an aeration amount fixed control method for setting the aeration amount to a predetermined fixed value, a flow rate proportional control method for variably controlling the aeration amount in proportion to the flow rate of the water to be treated W, and dissolved oxygen ( This is the DO constant control method for controlling the amount of aeration so as to keep DO) constant. In the following description of the operation, it is assumed that a correction according to the amount of nitrous oxide (N 2 O) is performed on the aeration amount determined by any of the above-described methods.

図３に示すステップＳ１１において、第１の曝気量制御部２５は、最新の（現在の）曝気量を取得する。第１の曝気量制御部２５は、送気用ブロワ１７に対して曝気量指令信号を発行することにより、曝気部１５，１７の曝気量を制御している。従って、第１の曝気量制御部２５は、自らが発行する曝気量指令信号を参照することによって、最新の（現在の）曝気量を取得することができる。   In step S11 illustrated in FIG. 3, the first aeration amount control unit 25 acquires the latest (current) aeration amount. The first aeration amount control unit 25 controls the aeration amount of the aeration units 15 and 17 by issuing an aeration amount command signal to the air supply blower 17. Therefore, the first aeration amount control unit 25 can acquire the latest (current) aeration amount by referring to the aeration amount command signal issued by itself.

ステップＳ１２において、N2O量相関値取得部２１は、ＯＲＰ計１９によるＯＲＰ検出値をサンプリングする。このサンプリングは、例えば、所定の周期に従って行ってもよいし、ＯＲＰ検出値を用いる所要のタイミングで不定期に行ってもよい。 In step S < b > 12, the N 2 O amount correlation value acquisition unit 21 samples the ORP detection value by the ORP meter 19. This sampling may be performed, for example, according to a predetermined cycle or irregularly at a required timing using the ORP detection value.

ステップＳ１３において、N2O量相関値取得部２１は、ステップＳ１２でサンプリングしたＯＲＰ検出値を、ＯＲＰ値とN2O量との対照表を用いて、N2O量の相関値に換算する。こうして取得したN2O量の相関値の情報は、第１の曝気量制御部２５に送られる。 In step S13, the N 2 O amount correlation value acquisition unit 21 converts the ORP detection value sampled in step S12 into a correlation value of the N 2 O amount using a comparison table of the ORP value and the N 2 O amount. . Information on the correlation value of the N 2 O amount acquired in this way is sent to the first aeration amount control unit 25.

ステップＳ１４において、第１の曝気量制御部２５の曝気量補正量演算部２７は、N2O量相関値取得部２１で取得された亜酸化窒素（N2O）の量の相関値と、曝気量補正量記憶部２３の記憶内容とに基づいて、亜酸化窒素（N2O）の量の相関値に対応する曝気部１５，１７の曝気量に係る適正補正量を求める。 In step S14, the aeration amount correction amount calculation unit 27 of the first aeration amount control unit 25 includes a correlation value of the amount of nitrous oxide (N 2 O) acquired by the N 2 O amount correlation value acquisition unit 21, and Based on the stored content of the aeration amount correction amount storage unit 23, an appropriate correction amount related to the aeration amount of the aeration units 15 and 17 corresponding to the correlation value of the amount of nitrous oxide (N 2 O) is obtained.

ステップＳ１５において、第１の曝気量制御部２５は、ステップＳ１４で求めた曝気量に係る適正補正量を用いて補正した曝気量を制御目標として、曝気部１５，１７の曝気量を制御する。こうした曝気量制御を実行した後、第１の曝気量制御部２５は、処理の流れをステップＳ１１へと戻し、以下の処理を行わせる。   In step S15, the first aeration amount control unit 25 controls the aeration amounts of the aeration units 15 and 17 with the aeration amount corrected using the appropriate correction amount related to the aeration amount obtained in step S14 as a control target. After executing such aeration amount control, the first aeration amount control unit 25 returns the flow of processing to step S11 and performs the following processing.

（本発明の第１実施形態に係る第１の生物学的水処理装置１１の作用効果）
第１の生物学的水処理装置１１によれば、亜酸化窒素（N2O）の測定値に基づいて生物反応槽１３の曝気量を制御する従来技術と比較して、次に述べる有利な作用効果を奏する。すなわち、第１の曝気量制御部２５は、選択された制御方式に従って適宜設定された曝気量を、N2O生成量の多少に応じて段階的に増減補正する。このため、硝化反応の適切な進行促進が図られる。その結果、生物反応槽１３内で起こる硝化反応の進行程度を表す硝化率が適正化される。従って、第１の生物学的水処理装置１１によれば、被処理水Ｗの水質の維持と亜酸化窒素（N2O）の生成量抑制を両立することができる。また、下水処理場などの水処理施設から排出されるCO2 量を削減することができる。 (Operational effect of the first biological water treatment apparatus 11 according to the first embodiment of the present invention)
According to the first biological water treatment apparatus 11, the following advantages are obtained in comparison with the conventional technique that controls the aeration amount of the biological reaction tank 13 based on the measured value of nitrous oxide (N 2 O). Has an effect. That is, the first aeration amount control unit 25 corrects the aeration amount appropriately set according to the selected control method in a stepwise manner in accordance with the amount of N 2 O generation. For this reason, appropriate progress promotion of nitrification reaction is achieved. As a result, the nitrification rate representing the progress of the nitrification reaction occurring in the biological reaction tank 13 is optimized. Therefore, according to the first biological water treatment apparatus 11, it is possible to achieve both the amount inhibition of maintaining and nitrous oxide in water quality of the water to be treated W (N 2 O). In addition, the amount of CO 2 emitted from water treatment facilities such as sewage treatment plants can be reduced.

［第２実施形態］
次に、本発明の第２実施形態に係る第２の生物学的水処理装置３１について、図面を参照して説明する。
（本発明の第２実施形態に係る第２の生物学的水処理装置３１の構成）
図４は、本発明の第２実施形態に係る第２の生物学的水処理装置３１の機能ブロック図である。図５は、生物反応槽１３内で硝化反応が進行してゆく過程における酸化還元電位（ＯＲＰ）に対する硝化率特性を表す図である。なお、第２実施形態に係る第２の生物学的水処理装置３１は、第１実施形態に係る第１の生物学的水処理装置１１と比べて、一部の構成要素が共通している。このため、これら両者間において共通の機能部には共通の符号を付し、その重複した説明を省略して、両者の相違点に注目して説明を進める。 [Second Embodiment]
Next, the second biological water treatment apparatus 31 according to the second embodiment of the present invention will be described with reference to the drawings.
(Configuration of the second biological water treatment apparatus 31 according to the second embodiment of the present invention)
FIG. 4 is a functional block diagram of the second biological water treatment apparatus 31 according to the second embodiment of the present invention. FIG. 5 is a diagram showing the nitrification rate characteristic with respect to the oxidation-reduction potential (ORP) in the process in which the nitrification reaction proceeds in the biological reaction tank 13. In addition, the 2nd biological water treatment apparatus 31 which concerns on 2nd Embodiment has a one part component in common compared with the 1st biological water treatment apparatus 11 which concerns on 1st Embodiment. . For this reason, common reference numerals are given to functional units that are common between the two, description thereof will be omitted, and description will be made focusing on the differences between the two.

第１実施形態に係る第１の生物学的水処理装置１１と、第２実施形態に係る第２の生物学的水処理装置３１との相違点は、次のとおりである。すなわち、第１実施形態に係る第１の生物学的水処理装置１１では、基準となる曝気量を予め設定しておき、設定された曝気量を、亜酸化窒素（N2O）の量に応じて段階的に補正するようにしている。
これに対し、第２実施形態に係る第２の生物学的水処理装置３１では、目標となる硝化率を予め設定しておき、設定された硝化率を、亜酸化窒素（N2O）の量に応じて段階的に補正するようにしている。 The differences between the first biological water treatment device 11 according to the first embodiment and the second biological water treatment device 31 according to the second embodiment are as follows. That is, in the first biological water treatment apparatus 11 according to the first embodiment, a reference aeration amount is set in advance, and the set aeration amount is set to the amount of nitrous oxide (N 2 O). The correction is made step by step accordingly.
On the other hand, in the second biological water treatment apparatus 31 according to the second embodiment, a target nitrification rate is set in advance, and the set nitrification rate is reduced to that of nitrous oxide (N 2 O). Correction is made in stages according to the amount.

前記した相違点に由来して、第２実施形態に係る第２の生物学的水処理装置３１は、図４に示すように、硝化率相関値取得部３３と、硝化率補正量記憶部３５と、目標硝化率記憶部３７と、第２の曝気量制御部３９と、を備えて構成される。   Due to the difference described above, the second biological water treatment apparatus 31 according to the second embodiment includes a nitrification rate correlation value acquisition unit 33 and a nitrification rate correction amount storage unit 35, as shown in FIG. And a target nitrification rate storage unit 37 and a second aeration amount control unit 39.

硝化率相関値取得部３３は、生物反応槽１３内で起こる硝化反応の進行程度を表す硝化率の相関値を取得する機能を有する。ＯＲＰ計１９によって計測されたＯＲＰ検出値は、第２の生物学的水処理装置３１において、硝化率の相関値として取り扱うことができる。その理由は、図５に示すように、生物反応槽１３内で硝化反応が進行している場合において、ＯＲＰ検出値と硝化率とは、所定の相関関係があるからである。要するに、ＯＲＰ値は、硝化反応の進行状態を表す間接的な指標となる。   The nitrification rate correlation value acquisition unit 33 has a function of acquiring a nitrification rate correlation value indicating the progress of the nitrification reaction occurring in the biological reaction tank 13. The ORP detection value measured by the ORP meter 19 can be handled as a correlation value of the nitrification rate in the second biological water treatment device 31. The reason is that, as shown in FIG. 5, when the nitrification reaction is proceeding in the biological reaction tank 13, the ORP detection value and the nitrification rate have a predetermined correlation. In short, the ORP value is an indirect index representing the progress of the nitrification reaction.

具体的には、硝化率相関値取得部３３は、例えば、ＯＲＰ検出値そのものを硝化率の相関値として取り扱ってもよいし、ＯＲＰ値と硝化率との対照表を用いて、ＯＲＰ検出値を硝化率に換算した値として取り扱ってもよい。また、ＯＲＰ値を硝化率に換算するための関係式を用いて、ＯＲＰ検出値を硝化率に換算した値として取り扱ってもよい。   Specifically, the nitrification rate correlation value acquisition unit 33 may handle, for example, the ORP detection value itself as the correlation value of the nitrification rate, or the ORP detection value using the comparison table of the ORP value and the nitrification rate. It may be handled as a value converted to nitrification rate. Further, the ORP detection value may be handled as a value converted into a nitrification rate using a relational expression for converting the ORP value into a nitrification rate.

硝化率補正量記憶部３５は、次の（表２）に示すように、単位時間あたりのN2O生成量に対する適正な硝化率補正量に係る第２の関係表を記憶している。この第２の関係表では、単位時間あたりのN2O生成量［ｇ／ｈ］を５段階に分けて、各段階毎に、相互に異なる適正な硝化率補正量［％］をそれぞれ対応づけて記述している。すなわち、第２の関係表には、N2O生成量：（１０＞）［ｇ／ｈ］に対して硝化率補正量：１０［％］が、N2O生成量：（１０〜２０）［ｇ／ｈ］に対して硝化率補正量：５［％］が、N2O生成量：（２０〜３０）［ｇ／ｈ］に対して硝化率補正量：０［％］が、N2O生成量：（３０〜５０）［ｇ／ｈ］に対して硝化率補正量：−５［％］が、N2O生成量：（５０＜）［ｇ／ｈ］に対して硝化率補正量：−１０［％］が、それぞれ対応づけて記述されている。 As shown in the following (Table 2), the nitrification rate correction amount storage unit 35 stores a second relational table relating to an appropriate nitrification rate correction amount with respect to the N 2 O generation amount per unit time. In this second relational table, the N 2 O production amount [g / h] per unit time is divided into five stages, and appropriate different nitrification rate correction amounts [%] are associated with each stage. Is described. That is, in the second relational table, the nitrification rate correction amount: 10 [%] with respect to the N 2 O production amount: (10>) [g / h], but the N 2 O production amount: (10-20) The nitrification rate correction amount: 5 [%] with respect to [g / h], the nitrification rate correction amount: 0 [%] with respect to N 2 O generation amount: (20-30) [g / h], N 2 O generation amount: (30-50) [g / h] nitrification rate correction amount: −5 [%], N 2 O generation amount: (50 <) [g / h] nitrification rate Correction amount: −10 [%] is described in association with each other.

要するに、第２の関係表では、N2O生成量が少ない場合は、硝化反応の促進が足りないものとみなして硝化率を増大させる補正を行い、N2O生成量が多い場合は、硝化反応の促進が過剰になされているものとみなして硝化率を減少させる補正を行い、N2O生成量が適正な場合は、硝化反応の促進が適切になされているものとみなして硝化率をそのまま維持させる（補正なし）といったように、第２の曝気量制御部３９が見かけ上の制御対象（実質的な制御対象は曝気量）とする硝化率を、N2O生成量の多少に応じて補正させることを狙っている。 In short, in the second relational table, when the amount of N 2 O produced is small, it is considered that the nitrification reaction is not promoted sufficiently, and the nitrification rate is corrected. When the amount of N 2 O produced is large, nitrification is performed. It is assumed that the reaction is promoted excessively, and correction is made to reduce the nitrification rate.If the amount of N 2 O produced is appropriate, the nitrification rate is considered to be promoted appropriately. The nitrification rate that the second aeration amount control unit 39 apparently controls (substantial control target is the aeration amount), such as maintaining it as it is (without correction), depending on the amount of N 2 O generation It aims to be corrected.

目標硝化率記憶部３７は、後記する補正によって時々刻々と変化する目標硝化率のうち最新のものを記憶保持している。第２の曝気量制御部３９は、硝化率補正量演算部４１と、目標硝化率演算部４３とを備える。硝化率補正量演算部４１は、N2O量相関値取得部２１で取得された亜酸化窒素（N2O）の量の相関値と、硝化率補正量記憶部３５の記憶内容とに基づいて、亜酸化窒素（N2O）の量の相関値に対応する硝化率に係る適正補正量を求める。 The target nitrification rate storage unit 37 stores and holds the latest target nitrification rate that changes every moment by correction described later. The second aeration amount control unit 39 includes a nitrification rate correction amount calculation unit 41 and a target nitrification rate calculation unit 43. The nitrification rate correction amount calculation unit 41 is based on the correlation value of the amount of nitrous oxide (N 2 O) acquired by the N 2 O amount correlation value acquisition unit 21 and the storage contents of the nitrification rate correction amount storage unit 35. Thus, an appropriate correction amount related to the nitrification rate corresponding to the correlation value of the amount of nitrous oxide (N 2 O) is obtained.

目標硝化率演算部４３は、目標硝化率記憶部３７に記憶されている現在の（最新の）目標硝化率と、硝化率補正量演算部４１で求められた硝化率に係る適正補正量とに基づいて、補正後の目標硝化率を求める。第２の曝気量制御部３９は、目標硝化率演算部４３で求められた補正後の目標硝化率を制御目標として、曝気部（散気部１５および送気用ブロワ１７；以下では、“曝気部１５，１７”と省略する。）の曝気量を制御するように動作する。   The target nitrification rate calculation unit 43 converts the current (latest) target nitrification rate stored in the target nitrification rate storage unit 37 and the appropriate correction amount related to the nitrification rate obtained by the nitrification rate correction amount calculation unit 41. Based on this, the corrected target nitrification rate is obtained. The second aeration amount control unit 39 uses the corrected target nitrification rate obtained by the target nitrification rate calculation unit 43 as a control target, and uses the aeration unit (aeration unit 15 and air supply blower 17; hereinafter, “aeration” It abbreviates as part 15, 17 ″.

（本発明の第２実施形態に係る第２の生物学的水処理装置３１の動作）
次に、本発明の第２実施形態に係る第２の生物学的水処理装置３１の動作について、図面を参照して説明する。図６は、本発明の第２実施形態に係る第２の生物学的水処理装置３１の動作説明に供するフローチャート図である。 (Operation of the second biological water treatment apparatus 31 according to the second embodiment of the present invention)
Next, operation | movement of the 2nd biological water treatment apparatus 31 which concerns on 2nd Embodiment of this invention is demonstrated with reference to drawings. FIG. 6 is a flowchart for explaining the operation of the second biological water treatment apparatus 31 according to the second embodiment of the present invention.

なお、本第２実施形態に係る第２の生物学的水処理装置３１では、次に述べるように、目標硝化率を予め設定しておき、設定された目標硝化率を、亜酸化窒素（N2O）の量に応じて段階的に補正するように動作する。ここで、目標硝化率を設定するにあたっては、いくつかの方式がある。すなわち、目標硝化率を所定の固定値に設定する目標硝化率固定制御方式と、生物反応槽１３内の溶存酸素（ＤＯ）を一定に維持するように目標硝化率を制御するＤＯ一定制御方式と、などがそれである。次に述べる動作説明では、前記したいずれかの方式により決定された目標硝化率に対して、亜酸化窒素（N2O）の量に応じた補正が行われるものとする。 In the second biological water treatment apparatus 31 according to the second embodiment, as described below, a target nitrification rate is set in advance, and the set target nitrification rate is set to nitrous oxide (N 2 Operates to correct in steps according to the amount of O). Here, there are several methods for setting the target nitrification rate. That is, a target nitrification rate fixed control method for setting the target nitrification rate to a predetermined fixed value, and a DO constant control method for controlling the target nitrification rate so as to keep the dissolved oxygen (DO) in the biological reaction tank 13 constant. , Etc. That's it. In the following description of the operation, it is assumed that correction according to the amount of nitrous oxide (N 2 O) is performed on the target nitrification rate determined by any of the above-described methods.

図６に示すステップＳ２１において、第２の曝気量制御部３９は、目標硝化率記憶部３７から最新の（現在の）目標硝化率を取得する。   In step S <b> 21 shown in FIG. 6, the second aeration amount control unit 39 acquires the latest (current) target nitrification rate from the target nitrification rate storage unit 37.

ステップＳ２２において、N2O量相関値取得部２１は、ＯＲＰ計１９によるＯＲＰ検出値をサンプリングする。このサンプリングは、例えば、所定の周期に従って行ってもよいし、ＯＲＰ検出値を用いる所要のタイミングで不定期に行ってもよい。 In step S < b > 22, the N 2 O amount correlation value acquisition unit 21 samples the ORP detection value by the ORP meter 19. This sampling may be performed, for example, according to a predetermined cycle or irregularly at a required timing using the ORP detection value.

ステップＳ２３において、N2O量相関値取得部２１は、ステップＳ２２でサンプリングしたＯＲＰ検出値を、ＯＲＰ値とN2O量との関係表を用いて、N2O量の相関値に換算する。こうして取得したN2O量の相関値は、第２の曝気量制御部３９の硝化率補正量演算部４１に送られる。 In step S23, the N 2 O amount correlation value acquisition unit 21 converts the ORP detection value sampled in step S22 into a correlation value of the N 2 O amount using a relationship table between the ORP value and the N 2 O amount. . The correlation value of the N 2 O amount acquired in this way is sent to the nitrification rate correction amount calculation unit 41 of the second aeration amount control unit 39.

ステップＳ２４において、硝化率相関値取得部３３は、ステップＳ２２でサンプリングしたＯＲＰ検出値を、ＯＲＰ値を硝化率に換算するための関係式を用いて、硝化率の相関値に換算する。こうして取得した硝化率の相関値は、第２の曝気量制御部３９に送られる。   In step S24, the nitrification rate correlation value acquisition unit 33 converts the ORP detection value sampled in step S22 into a nitrification rate correlation value using a relational expression for converting the ORP value into the nitrification rate. The correlation value of the nitrification rate acquired in this way is sent to the second aeration amount control unit 39.

ステップＳ２５において、第２の曝気量制御部３９の硝化率補正量演算部４１は、N2O量相関値取得部２１で取得された亜酸化窒素（N2O）の量の相関値と、硝化率補正量記憶部３５の記憶内容とに基づいて、亜酸化窒素（N2O）の量の相関値に対応する硝化率に係る適正補正量を求める。 In step S25, the nitrification rate correction amount calculation unit 41 of the second aeration amount control unit 39 includes the correlation value of the amount of nitrous oxide (N 2 O) acquired by the N 2 O amount correlation value acquisition unit 21, and Based on the stored contents of the nitrification rate correction amount storage unit 35, an appropriate correction amount related to the nitrification rate corresponding to the correlation value of the amount of nitrous oxide (N 2 O) is obtained.

ステップＳ２６において、第２の曝気量制御部３９の目標硝化率演算部４３は、目標硝化率記憶部３７に記憶されている現在の（最新の）目標硝化率と、ステップＳ２５で求められた硝化率に係る適正補正量とに基づいて、補正後の目標硝化率を求める。   In step S26, the target nitrification rate calculation unit 43 of the second aeration amount control unit 39 stores the current (latest) target nitrification rate stored in the target nitrification rate storage unit 37 and the nitrification obtained in step S25. The corrected target nitrification rate is obtained based on the appropriate correction amount related to the rate.

ステップＳ２７において、第２の曝気量制御部３９は、目標硝化率演算部４３で求められた補正後の目標硝化率を制御目標として、ステップＳ２４で取得した硝化率の相関値を補正後の目標硝化率に追従させることを考慮して、曝気部１５，１７の曝気量を制御する。こうした曝気量制御を実行した後、第２の曝気量制御部３９は、処理の流れをステップＳ２１へと戻し、以下の処理を行わせる。   In step S27, the second aeration amount control unit 39 uses the corrected target nitrification rate obtained by the target nitrification rate calculation unit 43 as a control target, and corrects the correlation value of the nitrification rate acquired in step S24. In consideration of following the nitrification rate, the amount of aeration of the aeration units 15 and 17 is controlled. After executing such aeration amount control, the second aeration amount control unit 39 returns the flow of processing to step S21 and performs the following processing.

（本発明の第２実施形態に係る第２の生物学的水処理装置３１の作用効果）
第２の生物学的水処理装置３１によれば、第２の曝気量制御部３９は、選択された制御方式に従って適宜設定された目標硝化率を、N2O生成量の多少に応じて段階的に増減補正する。このため、硝化反応における硝化率の適正化が図られる。従って、第２の生物学的水処理装置３１によれば、第１の生物学的水処理装置１１と同様に、被処理水Ｗの水質の維持と亜酸化窒素（N2O）の生成量抑制を両立することができる。また、下水処理場などの水処理施設から排出されるCO2 量を削減することができる。 (Operational effect of the second biological water treatment apparatus 31 according to the second embodiment of the present invention)
According to the second biological water treatment apparatus 31, the second aeration amount control unit 39 sets the target nitrification rate appropriately set according to the selected control method in accordance with the amount of N 2 O production. To increase or decrease automatically. For this reason, optimization of the nitrification rate in the nitrification reaction is achieved. Therefore, according to the second biological water treatment device 31, as in the first biological water treatment device 11, the water quality of the treated water W is maintained and the amount of nitrous oxide (N 2 O) produced It is possible to achieve both suppression. In addition, the amount of CO 2 emitted from water treatment facilities such as sewage treatment plants can be reduced.

［第３実施形態］
次に、本発明の第３実施形態に係る第３の生物学的水処理装置３１について、図面を参照して説明する。
（本発明の第３実施形態に係る第３の生物学的水処理装置５１の構成）
図７は、本発明の第３実施形態に係る第３の生物学的水処理装置５１の機能ブロック図である。なお、第３実施形態に係る第３の生物学的水処理装置５１は、第２実施形態に係る第２の生物学的水処理装置３１と比べて、一部の構成要素が共通している。このため、これら両者間において共通の機能部には共通の符号を付し、その重複した説明を省略して、両者の相違点に注目して説明を進める。 [Third Embodiment]
Next, a third biological water treatment apparatus 31 according to a third embodiment of the present invention will be described with reference to the drawings.
(Configuration of the third biological water treatment apparatus 51 according to the third embodiment of the present invention)
FIG. 7 is a functional block diagram of the third biological water treatment apparatus 51 according to the third embodiment of the present invention. In addition, the 3rd biological water treatment apparatus 51 which concerns on 3rd Embodiment has a one part common component compared with the 2nd biological water treatment apparatus 31 which concerns on 2nd Embodiment. . For this reason, common reference numerals are given to functional units that are common between the two, description thereof will be omitted, and description will be made focusing on the differences between the two.

第２実施形態に係る第２の生物学的水処理装置３１と、第３実施形態に係る第３の生物学的水処理装置５１との相違点は、次のとおりである。すなわち、第２実施形態に係る第２の生物学的水処理装置３１では、目標となる硝化率を予め設定しておき、設定された硝化率を、亜酸化窒素（N2O）の量に応じて段階的に補正するようにしている。 The differences between the second biological water treatment apparatus 31 according to the second embodiment and the third biological water treatment apparatus 51 according to the third embodiment are as follows. That is, in the second biological water treatment apparatus 31 according to the second embodiment, a target nitrification rate is set in advance, and the set nitrification rate is set to the amount of nitrous oxide (N 2 O). The correction is made step by step accordingly.

これに対し、第３実施形態に係る第３の生物学的水処理装置５１では、目標となる硝化率を予め設定しておき、設定された硝化率を、亜酸化窒素（N2O）の量に応じて段階的に補正する点は同じであるが、目標硝化率の補正タイミングを、亜酸化窒素（N2O）の量が許容できる上限値を超えた（許容範囲を逸脱した）タイミングと同期させている点が、第２実施形態に係る第２の生物学的水処理装置３１と相違している。 On the other hand, in the third biological water treatment apparatus 51 according to the third embodiment, a target nitrification rate is set in advance, and the set nitrification rate is changed to that of nitrous oxide (N 2 O). The point of correction in steps according to the amount is the same, but the timing for correcting the target nitrification rate is when the amount of nitrous oxide (N 2 O) exceeds the allowable upper limit (out of the allowable range) Is different from the second biological water treatment apparatus 31 according to the second embodiment.

前記した相違点に由来して、第３実施形態に係る第３の生物学的水処理装置５１は、N2O量許容値記憶部５３と、第３の曝気量制御部５５と、を備えて構成される。 Derived from the differences described above, the third biological water treatment apparatus 51 according to the third embodiment is provided with N 2 O amount permissible value storage unit 53, and the third aeration amount control section 55, the Configured.

N2O量許容値記憶部５３は、亜酸化窒素（N2O）の量に係る許容値を記憶している。亜酸化窒素（N2O）の量に係る許容値としては、許容できる亜酸化窒素（N2O）の量の上限値、または、許容できる亜酸化窒素（N2O）の量の下限値および上限値の組み合わせからなる許容範囲のうちいずれかを採用すればよい。 The N 2 O amount allowable storage unit 53 stores an allowable value related to the amount of nitrous oxide (N 2 O). The tolerance of the amount of nitrous oxide (N 2 O), the upper limit of the amount of acceptable nitrous oxide (N 2 O), or the amount of the lower limit of acceptable nitrous oxide (N 2 O) One of the allowable ranges consisting of a combination of the upper limit value and the upper limit value may be adopted.

第３の曝気量制御部５５は、図５に示す硝化率補正量演算部４１および目標硝化率演算部４３の他に、ＯＲＰ設定値演算部５７を備える。硝化率補正量演算部４１は、N2O量相関値取得部２１で取得された亜酸化窒素（N2O）の量の相関値と、硝化率補正量記憶部３５の記憶内容とに基づいて、亜酸化窒素（N2O）の量の相関値に対応する硝化率に係る適正補正量を求める。目標硝化率演算部４３は、目標硝化率記憶部３７に記憶されている現在の（最新の）目標硝化率と、硝化率補正量演算部４１で求められた硝化率に係る適正補正量とに基づいて、補正後の目標硝化率を求める。 The third aeration amount control unit 55 includes an ORP set value calculation unit 57 in addition to the nitrification rate correction amount calculation unit 41 and the target nitrification rate calculation unit 43 shown in FIG. The nitrification rate correction amount calculation unit 41 is based on the correlation value of the amount of nitrous oxide (N 2 O) acquired by the N 2 O amount correlation value acquisition unit 21 and the storage contents of the nitrification rate correction amount storage unit 35. Thus, an appropriate correction amount related to the nitrification rate corresponding to the correlation value of the amount of nitrous oxide (N 2 O) is obtained. The target nitrification rate calculation unit 43 converts the current (latest) target nitrification rate stored in the target nitrification rate storage unit 37 and the appropriate correction amount related to the nitrification rate obtained by the nitrification rate correction amount calculation unit 41. Based on this, the corrected target nitrification rate is obtained.

ＯＲＰ設定値演算部５７は、目標硝化率演算部４３で求められた補正後の目標硝化率と、図５に示すＯＲＰ値に対応する硝化率を換算するための関係式（ＯＲＰ設定値演算部５７に与えられている。）とに基づいて、補正後の目標硝化率に対応するＯＲＰ値を求め、こうして求めたＯＲＰ値をＯＲＰ設定値とする。ここで、ＯＲＰ設定値とは、目標消化率をＯＲＰ値に換算した値である。第３の曝気量制御部５５は、ＯＲＰ設定値演算部５７で求められた補正後の目標硝化率に対応するＯＲＰ設定値を制御目標として、ＯＲＰ計１９により計測されたＯＲＰ検出値２１ａをＯＲＰ設定値に追従させることを考慮して、曝気部（散気部１５および送気用ブロワ１７；以下では、“曝気部１５，１７”と省略する。）の曝気量を制御するように動作する。   The ORP set value calculation unit 57 is a relational expression (ORP set value calculation unit for converting the corrected target nitrification rate obtained by the target nitrification rate calculation unit 43 and the nitrification rate corresponding to the ORP value shown in FIG. The ORP value corresponding to the corrected target nitrification rate is obtained on the basis of the above, and the ORP value thus obtained is set as the ORP set value. Here, the ORP set value is a value obtained by converting the target digestibility into an ORP value. The third aeration amount control unit 55 ORPs the ORP detection value 21a measured by the ORP meter 19 using the ORP set value corresponding to the corrected target nitrification rate obtained by the ORP set value calculation unit 57 as a control target. In consideration of following the set value, the aeration unit (aeration unit 15 and air supply blower 17; hereinafter, abbreviated as “aeration units 15 and 17”) operates to control the aeration amount. .

（本発明の第３実施形態に係る第３の生物学的水処理装置５１の動作）
次に、本発明の第３実施形態に係る第３の生物学的水処理装置５１の動作について、図面を参照して説明する。図８は、本発明の第３実施形態に係る第３の生物学的水処理装置５１の動作説明に供するフローチャート図である。 (Operation of the third biological water treatment apparatus 51 according to the third embodiment of the present invention)
Next, operation | movement of the 3rd biological water treatment apparatus 51 which concerns on 3rd Embodiment of this invention is demonstrated with reference to drawings. FIG. 8 is a flowchart for explaining the operation of the third biological water treatment apparatus 51 according to the third embodiment of the present invention.

なお、本第３実施形態に係る第３の生物学的水処理装置５１では、第２実施形態に係る第２の生物学的水処理装置３１と同様に、目標硝化率を予め設定しておき、設定された目標硝化率を、亜酸化窒素（N2O）の量に応じて段階的に補正するように動作する。また、目標硝化率の設定態様についても、第２実施形態に係る第２の生物学的水処理装置３１と同じである。 In the third biological water treatment apparatus 51 according to the third embodiment, a target nitrification rate is set in advance as in the second biological water treatment apparatus 31 according to the second embodiment. The target nitrification rate is set so as to be corrected step by step according to the amount of nitrous oxide (N 2 O). The setting mode of the target nitrification rate is also the same as that of the second biological water treatment apparatus 31 according to the second embodiment.

図８に示すステップＳ３１において、第３の曝気量制御部５５は、目標硝化率記憶部３７から最新の（現在の）目標硝化率を取得する。   In step S31 shown in FIG. 8, the third aeration amount control unit 55 acquires the latest (current) target nitrification rate from the target nitrification rate storage unit 37.

ステップＳ３２において、N2O量相関値取得部２１は、ＯＲＰ計１９によるＯＲＰ検出値２１ａをサンプリングする。このサンプリングは、例えば、所定の周期に従って行ってもよいし、ＯＲＰ検出値２１ａを用いる所要のタイミングで不定期に行ってもよい。 In step S < b > 32, the N 2 O amount correlation value acquisition unit 21 samples the ORP detection value 21 a by the ORP meter 19. This sampling may be performed according to a predetermined cycle, for example, or may be performed irregularly at a required timing using the ORP detection value 21a.

ステップＳ３３において、N2O量相関値取得部２１は、ステップＳ２２でサンプリングしたＯＲＰ検出値２１ａを、ＯＲＰ値とN2O量との関係表を用いて、N2O量の相関値に換算する。こうして取得したN2O量の相関値は、第３の曝気量制御部５５に送られる。 In step S33, the N 2 O amount correlation value acquisition unit 21 converts the ORP detection value 21a sampled in step S22 into a correlation value of the N 2 O amount using the relationship table between the ORP value and the N 2 O amount. To do. The correlation value of the N 2 O amount acquired in this way is sent to the third aeration amount control unit 55.

ステップＳ３４において、第３の曝気量制御部５５は、ステップＳ３３で取得したN2O量の相関値と、N2O量許容値記憶部５３に記憶されている、許容できる亜酸化窒素（N2O）の量の上限値とに基づいて、N2O量が許容値の上限を超えているか否かを判定する。 In step S < b > 34, the third aeration amount control unit 55 accepts an allowable nitrous oxide (N) stored in the correlation value of the N 2 O amount acquired in step S < b > 33 and the N 2 O amount allowable value storage unit 53. Based on the upper limit of the amount of 2 O), it is determined whether or not the N 2 O amount exceeds the upper limit of the allowable value.

ステップＳ３４の判定の結果、N2O量が許容値の上限を超えていない場合、第３の曝気量制御部５５は、処理の流れをステップＳ３１へと戻し、以下の処理を実行させる。 As a result of the determination in step S34, if the N 2 O amount does not exceed the upper limit of the allowable value, the third aeration amount control unit 55 returns the process flow to step S31 and executes the following process.

一方、ステップＳ３４の判定の結果、N2O量が許容値の上限を超えている場合、第３の曝気量制御部５５は、処理の流れを次のステップＳ３５へと進ませる。 On the other hand, as a result of the determination in step S34, if the N 2 O amount exceeds the upper limit of the allowable value, the third aeration amount control unit 55 advances the process flow to the next step S35.

ステップＳ３５において、第３の曝気量制御部５５の硝化率補正量演算部４１は、ステップＳ３３で取得した亜酸化窒素（N2O）の量の相関値と、硝化率補正量記憶部３５の記憶内容とに基づいて、亜酸化窒素（N2O）の量の相関値に対応する硝化率に係る適正補正量を求める。 In step S35, the nitrification rate correction amount calculation unit 41 of the third aeration amount control unit 55 stores the correlation value between the amounts of nitrous oxide (N 2 O) acquired in step S33 and the nitrification rate correction amount storage unit 35. Based on the stored contents, an appropriate correction amount related to the nitrification rate corresponding to the correlation value of the amount of nitrous oxide (N 2 O) is obtained.

ステップＳ３６において、第３の曝気量制御部５５の目標硝化率演算部４３は、目標硝化率記憶部３７に記憶されている現在の（最新の）目標硝化率と、ステップＳ３５で求められた硝化率に係る適正補正量とに基づいて、補正後の目標硝化率を求める。   In step S36, the target nitrification rate calculation unit 43 of the third aeration amount control unit 55 and the current (latest) target nitrification rate stored in the target nitrification rate storage unit 37 and the nitrification obtained in step S35. The corrected target nitrification rate is obtained based on the appropriate correction amount related to the rate.

ステップＳ３７において、第３の曝気量制御部５５のＯＲＰ設定値演算部５７は、ステップＳ３６で求められた補正後の目標硝化率と、ＯＲＰ値に対応する硝化率を換算するための関係式とに基づいて、補正後の目標硝化率に対応するＯＲＰ値を求め、こうして求めたＯＲＰ値をＯＲＰ設定値とする。次のステップＳ３８では、ＯＲＰ検出値２１ａを現在の硝化率に、ＯＲＰ設定値を目標硝化率に、それぞれ置き換えて取り扱うことができる。こうした置き換えは、ＯＲＰに対応する硝化率を換算するための関係式が介在することによって実現することができる。   In step S37, the ORP set value calculator 57 of the third aeration amount controller 55 calculates the corrected target nitrification rate obtained in step S36 and the relational expression for converting the nitrification rate corresponding to the ORP value. Based on the above, an ORP value corresponding to the corrected target nitrification rate is obtained, and the ORP value thus obtained is set as an ORP set value. In the next step S38, the ORP detection value 21a can be replaced with the current nitrification rate, and the ORP set value can be replaced with the target nitrification rate. Such replacement can be realized by interposing a relational expression for converting the nitrification rate corresponding to ORP.

ステップＳ３８において、第３の曝気量制御部５５は、ステップＳ３７で求められた補正後の目標硝化率に対応するＯＲＰ設定値を制御目標として、ＯＲＰ計１９により計測されたＯＲＰ検出値２１ａをＯＲＰ設定値に追従させることを考慮して、曝気部１５，１７の曝気量を制御する。こうした曝気量制御を実行した後、第３の曝気量制御部５５は、処理の流れをステップＳ３１へと戻し、以下の処理を行わせる。   In step S38, the third aeration amount control unit 55 ORP detects the ORP detection value 21a measured by the ORP meter 19 using the ORP set value corresponding to the corrected target nitrification rate obtained in step S37 as a control target. The aeration amount of the aeration units 15 and 17 is controlled in consideration of following the set value. After executing such aeration amount control, the third aeration amount control unit 55 returns the flow of processing to step S31 and performs the following processing.

（本発明の第３実施形態に係る第３の生物学的水処理装置５１の作用効果）
第３の生物学的水処理装置５１によれば、第３の曝気量制御部５５は、選択された制御方式に従って適宜設定された目標硝化率を、N2O生成量の多少に応じて段階的に増減補正する。また、目標硝化率の補正タイミングを、亜酸化窒素（N2O）の量が許容できる上限値を超えた（許容範囲を逸脱した）タイミングと同期させるようにしたので、適切なタイミングをもって、硝化反応における硝化率の適正化が図られる。従って、第３の生物学的水処理装置５１によれば、第２の生物学的水処理装置３１と同様に、被処理水Ｗの水質の維持と亜酸化窒素（N2O）の生成量抑制を両立することができる。また、下水処理場などの水処理施設から排出されるCO2 量を削減することができる。 (Effects of the third biological water treatment apparatus 51 according to the third embodiment of the present invention)
According to the third biological water treatment apparatus 51, the third aeration amount control unit 55 sets the target nitrification rate appropriately set according to the selected control method in accordance with the amount of N 2 O production. To increase or decrease automatically. The target nitrification rate correction timing is synchronized with the timing when the amount of nitrous oxide (N 2 O) exceeds the allowable upper limit (departs from the allowable range). The nitrification rate in the reaction is optimized. Therefore, according to the third biological water treatment apparatus 51, as in the second biological water treatment apparatus 31, the water quality of the treated water W is maintained and the amount of nitrous oxide (N 2 O) produced It is possible to achieve both suppression. In addition, the amount of CO 2 emitted from water treatment facilities such as sewage treatment plants can be reduced.

［その他の実施形態］
以上説明した複数の実施形態は、本発明の具現化例を示したものである。従って、これらによって本発明の技術的範囲が限定的に解釈されることがあってはならない。本発明はその要旨またはその主要な特徴から逸脱することなく、様々な形態で実施することができるからである。 [Other Embodiments]
The plurality of embodiments described above show examples of implementation of the present invention. Therefore, the technical scope of the present invention should not be limitedly interpreted by these. This is because the present invention can be implemented in various forms without departing from the gist or main features thereof.

最後に、本発明は、活性汚泥を用いた生物学的水処理であれば、標準活性汚泥法、嫌気−好気法、嫌気−無酸素−好気法などのあらゆる水処理方式に適用することができる。   Finally, the present invention is applicable to all water treatment methods such as standard activated sludge method, anaerobic-aerobic method, anaerobic-anoxic-aerobic method, etc., as long as it is a biological water treatment using activated sludge. Can do.

１１ 第１の生物学的水処理装置
１３ 生物反応槽
１５ 散気部（曝気部）
１７ 送気用ブロワ（曝気部）
１９ 酸化還元電位（ＯＲＰ）計
２１ N2O量相関値取得部
２３ 曝気量補正量記憶部
２５ 第１の曝気量制御部
２７ 曝気量補正量演算部
３１ 第２の生物学的水処理装置
３３ 硝化率相関値取得部
３５ 硝化率補正量記憶部
３７ 目標硝化率記憶部
３９ 第２の曝気量制御部
４１ 硝化率補正量演算部
４３ 目標硝化率演算部
５１ 第３の生物学的水処理装置
５３ N2O量許容値記憶部
５５ 第３の曝気量制御部
５７ ＯＲＰ設定値演算部 11 First biological water treatment device 13 Biological reaction tank 15 Aeration unit (aeration unit)
17 Blower for air supply (aeration part)
19 Redox potential (ORP) meter 21 N 2 O amount correlation value acquisition unit 23 Aeration amount correction amount storage unit 25 First aeration amount control unit 27 Aeration amount correction amount calculation unit 31 Second biological water treatment device 33 Nitrification rate correlation value acquisition unit 35 Nitrification rate correction amount storage unit 37 Target nitrification rate storage unit 39 Second aeration amount control unit 41 Nitrification rate correction amount calculation unit 43 Target nitrification rate calculation unit 51 Third biological water treatment device 53 N 2 O amount allowable value storage unit 55 Third aeration amount control unit 57 ORP set value calculation unit

Claims (2)

酸素が溶存している好気性環境に置かれた活性汚泥のはたらきにより、被処理水中のアンモニア性窒素（ＮＨ4 −Ｎ）を硝酸性窒素（ＮＯ3 −Ｎ）に生物学的に分解する生物学的水処理装置であって、
前記被処理水と共に前記活性汚泥が溜められた生物反応槽と、
前記生物反応槽内において曝気を行う曝気部と、
前記生物反応槽内の亜酸化窒素（N2O）の量の相関値を、前記生物反応槽内に設けられた酸化還元電位計の検出値に基づき取得するN2O量相関値取得部と、
前記生物反応槽内で起こる硝化反応の進行程度を表す硝化率の目標として予め設定された目標硝化率を記憶する目標硝化率記憶部と、
前記生物反応槽内の亜酸化窒素（N2O）の量の相関値に対応する、前記目標硝化率に係る適正補正量の関係を記憶する硝化率補正量記憶部と、
前記曝気部の曝気量を制御する曝気量制御部と、
を備え、
前記曝気量制御部は、前記N2O量相関値取得部で取得された前記亜酸化窒素（N2O）の量の相関値と、前記硝化率補正量記憶部の記憶内容とに基づいて、前記亜酸化窒素（N2O）の量の相関値に対応する前記目標硝化率に係る適正補正量を求めると共に、この目標硝化率に係る適正補正量を用いて補正した前記目標硝化率を制御目標として前記曝気部の曝気量を制御する、
ことを特徴とする生物学的水処理装置。 An organism that biologically decomposes ammoniacal nitrogen (NH 4 -N) in treated water into nitrate nitrogen (NO 3 -N) by the action of activated sludge placed in an aerobic environment in which oxygen is dissolved Water treatment device,
A biological reaction tank in which the activated sludge is stored together with the water to be treated;
An aeration unit for performing aeration in the biological reaction tank;
An N 2 O amount correlation value acquisition unit that acquires a correlation value of the amount of nitrous oxide (N 2 O) in the biological reaction tank based on a detection value of an oxidation-reduction potentiometer provided in the biological reaction tank; ,
A target nitrification rate storage unit that stores a target nitrification rate that is set in advance as a nitrification rate target that represents the degree of progress of the nitrification reaction that occurs in the biological reaction tank;
A nitrification rate correction amount storage unit that stores a relationship of an appropriate correction amount related to the target nitrification rate , corresponding to a correlation value of the amount of nitrous oxide (N 2 O) in the biological reaction tank;
An aeration amount control unit for controlling the aeration amount of the aeration unit;
With
The aeration amount control unit is based on the correlation value of the nitrous oxide (N 2 O) amount acquired by the N 2 O amount correlation value acquisition unit and the storage content of the nitrification rate correction amount storage unit. And obtaining an appropriate correction amount related to the target nitrification rate corresponding to the correlation value of the amount of nitrous oxide (N 2 O), and correcting the target nitrification rate using the appropriate correction amount related to the target nitrification rate. Control the amount of aeration of the aeration unit as a control target,
A biological water treatment apparatus characterized by that. 請求項１に記載の生物学的水処理装置であって、
前記曝気量制御部は、前記N 2 O量相関値取得部で取得された前記亜酸化窒素（N 2 O）の量の相関値が、許容できる亜酸化窒素（N 2 O）の量の下限値および上限値の組み合わせからなる亜酸化窒素（N 2 O）の量の許容範囲を逸脱した場合に、前記前記亜酸化窒素（N 2 O）の量の相関値と、前記硝化率補正量記憶部の記憶内容とに基づいて、前記亜酸化窒素（N 2 O）の量の相関値に対応する前記目標硝化率に係る適正補正量を求めると共に、この目標硝化率に係る適正補正量を用いて補正した前記目標硝化率を制御目標として前記曝気部の曝気量を制御する、
ことを特徴とする生物学的水処理装置。 The biological water treatment device according to claim 1,
The aeration amount control unit is configured such that the correlation value of the amount of nitrous oxide (N 2 O) acquired by the N 2 O amount correlation value acquisition unit is an allowable lower limit of the amount of nitrous oxide (N 2 O). A correlation value between the amount of nitrous oxide (N 2 O) and the nitrification rate correction amount storage when an allowable range of the amount of nitrous oxide (N 2 O) comprising a combination of a value and an upper limit value is deviated And calculating an appropriate correction amount related to the target nitrification rate corresponding to the correlation value of the amount of nitrous oxide (N 2 O) based on the stored content of the unit, and using the appropriate correction amount related to the target nitrification rate The amount of aeration of the aeration unit is controlled with the target nitrification rate corrected as a control target.
A biological water treatment apparatus characterized by that.
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