JP3707083B2 - Nitrification apparatus and method of operating nitrification apparatus - Google Patents
Nitrification apparatus and method of operating nitrification apparatus Download PDFInfo
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Description
【0001】
【産業上の利用分野】
本発明は硝化処理装置及び硝化処理装置の運転方法に係り、特に、装置の立ち上げや硝化活性の回復を短期間で容易かつ自動的に行える硝化処理装置及び硝化処理装置の運転方法に関する。
【0002】
【従来の技術】
従来、排水の生物的窒素除去装置として、硝化槽、脱窒槽及び沈殿池から構成される浮遊式活性汚泥方式のものが代表的である。このような生物的窒素除去装置において、装置の初期立ち上げや、定期点検・年末年始等の装置起動後の運転停止時における通水再開時の立ち上げに際しては、1日に1回、原水(被処理排水)を採水し、手分析によりアンモニア性窒素を測定し、アンモニア性窒素濃度が十分に低下していると判断した場合に負荷量を調整して、活性を回復させる方法が一般的である。この方法では、立ち上げまでに、約1ヶ月という長期間が必要であった。
【0003】
また、長期間、硝化槽の負荷が低下した後の活性回復の際においても、上記のような調整方法では、1週間程度の期間を必要とすることから、従来の方法では、原水水質の変動に対応することが事実上不可能であった。このため、負荷変動に対応するために、負荷が低下した際には、人為的に窒素源を添加して、負荷が再び増加したときに対処できる活性を維持する必要があった。
【0004】
【発明が解決しようとする課題】
上述の如く、従来の方法では、
▲1▼ 立ち上げに1ヶ月程度の長い期間を必要とする。
▲2▼ 立ち上げ期間中、分析や負荷量の調整に人手を必要とする。
▲3▼ 立ち上げの状態の判断には経験を要し、専門家の派遣を必要とする場合もある。
▲4▼ 短期的な負荷変動に対応するためには、装置活性を維持し続ける必要があり、このために窒素源の添加が必要となる。
といった問題があった。
【0005】
従来において、硝化処理水のアンモニア性窒素濃度から負荷の増減を行う方法も提案されているが、この方法においても、以下に記述する理由により、十分な効果は得られない。
【0006】
即ち、硝化部のアンモニア性窒素濃度と硝化速度の関係は一般的にMonod 式で表わされ、窒素濃度がある値より下回ると急速に低下する。図3は硝化部のアンモニア性窒素濃度と硝化速度との関係を示すグラフであるが、図3より明らかなように、硝化速度は、アンモニア性窒素濃度が1mg/lを下回ると低下を始め、0.5mg/l程度で最大値の約半分に低下してしまう。つまり、硝化細菌を最大の速度で増殖させ続け、できる限り短時間で立ち上げを完了させるためには、常にアンモニア性窒素濃度を2mg/l以上に保つ必要があることがわかる。
【0007】
ところで、実装置での立ち上げ時には、立ち上げの期間を短縮することの他に、処理水質を規制値以下に維持しつつ負荷を増加させる必要がある場合が殆どである。
【0008】
硝化細菌は、その増殖により硝化活性は1日で約20〜40%増加する。一方、負荷量の調整を上述の如く、手動操作で行う場合、調整頻度は実際には1日に1度が限界である。
【0009】
このようなことから、従来の方法では、処理水のアンモニア性窒素濃度が低くなったことを確認した後、1日に1回の調整操作で階段状に負荷を増加させているが、この場合に処理水質が制限内に収まる範囲でしか負荷量の増加を行えないために、処理水質の安全を考慮すればするほど負荷の変化幅を大きく設定することができず、次の調整の前には、アンモニア性窒素濃度が低下し増殖速度が遅くなってしまうことが多かった。
【0010】
本発明は上記従来の問題点を解決し、硝化槽の立ち上げに際し、処理水質を維持した上で、短期間で容易に立ち上げることができ、また、負荷変動にも良好に対応して硝化活性の回復も容易に行うことができ、しかも、これら立ち上げや活性回復のための負荷調整を自動的に行える硝化処理装置及び硝化処理装置の運転方法を提供することを目的とする。
【0011】
【課題を解決するための手段】
本発明の硝化処理装置は、硝化槽と、該硝化槽の硝化処理水のアンモニア性窒素濃度を測定する手段と、測定されたアンモニア性窒素濃度を予め設定されたアンモニア性窒素濃度と比較し、測定値が設定値以下のときに、測定値が設定値以上となるように、窒素源の添加又は原水の流量の調整によって該硝化槽の窒素負荷量を調整する制御手段とを備えてなることを特徴とする。
本発明の硝化処理装置の運転方法は、上記本発明の硝化処理装置の運転方法であって、該硝化処理装置の立ち上げ又は硝化活性を回復させる際に、前記アンモニア性窒素濃度測定手段の測定値と予め設定されたアンモニア性窒素濃度とを比較し、測定値が設定値以上となるように、前記制御手段によって、窒素源の添加又は原水の流量の調整をすることにより前記硝化槽の窒素負荷量を調整することを特徴とする。
【0012】
【作用】
本発明の硝化処理装置及び硝化処理装置の運転方法によれば、硝化処理水のアンモニア性窒素濃度の設定値を、例えば、1〜10mg/lの範囲で設定しておき、硝化処理水のアンモニア性窒素濃度の測定値が設定値以下となったときには、測定値がこの設定値以上となるように迅速に負荷調整を行うことができる。このため、窒素濃度が低下して硝化菌の増殖速度が低下する前に、負荷調整することが可能となり、これにより、処理水質を維持した上で、常に最大の速度で硝化菌を増殖させることができる。
【0013】
従って、極めて短期間で硝化処理装置の立ち上げを完了することができ、また、立ち上げ期間中の処理水質も規制値以下に抑えることができる。
【0014】
本発明の硝化処理装置及び硝化処理装置の運転方法では、装置の活性回復も容易に行えるため、負荷が低減した際に、窒素源を添加することなく処理を行って、高負荷となる1〜2日前から回復のための操作を行えば良く、容易に負荷の増加にも対応できる。
【0015】
【実施例】
以下、図面を参照して本発明をより具体的に説明する。
【0016】
図1は本発明の硝化処理装置の一実施例を示す系統図である。
【0017】
本実施例の硝化処理装置は硝化槽として硝化脱窒槽1を備えるものである。即ち、硝化脱窒槽1は、その中間部分に散気管2を備え、処理水の一部を配管12より槽下部に循環している。この硝化脱窒槽1においては、散気管2の上部が硝化部1A、散気管2の下部が脱窒部1Bとなり、硝化部1Aで配管11より導入される原水中のアンモニア性窒素が硝酸性窒素となり、これが循環水として配管12より脱窒部1Bに循環され、この脱窒部1Bで還元されて窒素ガスとして除去される。硝化脱窒槽1の処理水は配管13より系外へ排出される。
【0018】
本実施例においては、原水の導入配管11に窒素源貯槽6内の硫酸アンモニウム等の窒素源を、添加ポンプ5を備える配管14を経て注入することにより負荷調整を行うが、この負荷調整に当り、硝化脱窒槽1の硝化部1Aの上部に設けたアンモニア性窒素濃度計(アンモニア濃度計)3で硝化処理液のアンモニア性窒素濃度を測定し、この測定値に基いて演算装置4で添加ポンプ5の作動を制御する。
【0019】
即ち、演算装置4において、アンモニア性窒素濃度計3の測定値と予め定めた設定値とを比較し、測定値が設定値以下である場合には、設定値以上のアンモニア性窒素濃度が測定されるまで添加ポンプ5を作動させる信号を発信し、窒素源の添加制御を行う。
【0020】
これにより、窒素濃度が低下して硝化菌の増殖速度が低下する前に、負荷調整することが可能となり、処理水質を維持した上で、常に最大の速度で硝化菌を増殖させることができる。
【0021】
なお、図1に示す硝化処理装置は本発明の一実施例であって、本発明はその要旨を超えない限り、何ら図示のものに限定されるものではない。
【0022】
例えば、硝化槽は、硝化脱窒を行うものに限られず、硝化のみを行い、別途、脱窒槽を設けるものであっても良い。また、硝化槽の形式についても浮遊方式、生物濾過方式、流動床方式のいずれであっても良い。
【0023】
更に、負荷調整は、窒素源を添加する方法に限らず、原水の流量を調整する方法であっても良い。即ち、負荷量を上げる場合には、原水流入量を増加させて、処理水中に窒素が所定値以上残留するようにすることもできる。通常の場合、窒素源を添加する方法は、原水の窒素濃度が低い場合に有効であり、原水の流入量の調整による方法は、原水の窒素濃度が高い場合に有効である。
【0024】
なお、本発明において、アンモニア性窒素濃度の設定値は、処理水質の規制値や必要とされる立ち上げ効率等によって適宜決定されるが、通常の場合1〜10mg/lの範囲とされる。
【0025】
以下に具体的な実施例及び比較例を挙げて、本発明をより詳細に説明する。
【0026】
実施例1
図1に示す一槽式の窒素除去装置を用いて、定期点検のため約1ヶ月間停止した装置の立ち上げを行った。
【0027】
装置の設計能力は0.7kg−N/m3 ・日、停止後、立ち上げ時の硝化速度は約0.4kg−N/m3 ・日であった。原水窒素濃度は60mg/lで、処理水の規制値はT−N8mg/lであった。
【0028】
通水再開後、処理水のアンモニア性窒素濃度を15分毎に半連続的に測定し、処理水のアンモニア性窒素濃度の設定値を1.5mg/lとして演算装置により1時間に1度窒素源として硫酸アンモニウムを添加することにより、窒素源の添加量を調整した。
【0029】
このときの硝化性能の回復状態を図2に示す。
【0030】
比較例1
実施例1において、通水再開後、1日に1回負荷量を調整した。負荷量は、通水再開日の0.4kg−N/m3 ・日に対して、1日当りその10%ずつ増加させた。
【0031】
このときの硝化性能の回復状態を図2に示す。
【0032】
図2より明らかなように、本発明によれば、従来の人手による場合に比べて、立ち上げに要する時間は約半分以下と、飛躍的に短縮される。
【0033】
【発明の効果】
以上詳述した通り、本発明の硝化処理装置及び硝化処理装置の運転方法によれば、硝化処理水のアンモニア性窒素濃度に基いて自動的に窒素負荷量を調整することにより、
(1) 硝化処理の開始又は再開に際し、装置の立ち上げ期間を大幅に短縮することができる。
(2) 立ち上げ期間内においても処理水質を規制値以下に維持することができる。
(3) 処理継続中において、原水水質が変動して硝化活性が低下した場合においても、処理水質を維持した上で、活性を早期に回復させることができる。
といった優れた効果を得ることができ、負荷調整に人手を要することなく、効率的な硝化処理を行える。
【図面の簡単な説明】
【図1】本発明の硝化処理装置の一実施例を示す系統図である。
【図2】実施例1及び比較例1の硝化性能回復状態を示すグラフである。
【図3】硝化部のアンモニア性窒素濃度と硝化速度との関係を示すグラフである。
【符号の説明】
1 硝化脱窒槽
1A 硝化部
1B 脱窒部
2 散気管
3 アンモニア性窒素濃度計
4 演算装置
5 添加ポンプ
6 窒素源貯槽[0001]
[Industrial application fields]
The present invention relates to a nitrification apparatus and a method for operating the nitrification apparatus, and more particularly to a nitrification apparatus and a method for operating the nitrification apparatus that can easily and automatically start up the apparatus and recover nitrification activity in a short period of time.
[0002]
[Prior art]
Conventionally, as a biological nitrogen removing apparatus for waste water, a floating activated sludge system composed of a nitrification tank, a denitrification tank and a sedimentation basin is representative. In such a biological nitrogen removal device, when starting up the device at the initial start-up or when restarting the water flow after the start-up of the device such as periodic inspection and year-end / new year, the raw water ( A common method is to recover the activity by sampling the wastewater to be treated), measuring ammonia nitrogen by manual analysis, and adjusting the load when it is judged that the ammonia nitrogen concentration has sufficiently decreased. It is. This method required a long period of about one month to start up.
[0003]
In addition, even when recovering the activity after the load of the nitrification tank has been reduced for a long time, the adjustment method as described above requires a period of about one week. It was virtually impossible to deal with For this reason, in order to cope with load fluctuations, it is necessary to artificially add a nitrogen source when the load decreases to maintain activity that can be coped with when the load increases again.
[0004]
[Problems to be solved by the invention]
As described above, in the conventional method,
(1) It takes a long period of about one month for startup.
(2) During the start-up period, manpower is required for analysis and adjustment of load.
(3) Judgment of the state of start-up requires experience and may require dispatch of experts.
(4) In order to cope with short-term load fluctuations, it is necessary to maintain the apparatus activity, and for this reason, the addition of a nitrogen source is necessary.
There was a problem.
[0005]
Conventionally, a method for increasing / decreasing the load from the ammoniacal nitrogen concentration of nitrification water has also been proposed, but even this method cannot provide a sufficient effect for the reason described below.
[0006]
That is, the relationship between the ammoniacal nitrogen concentration in the nitrification part and the nitrification rate is generally expressed by the Monod equation, and rapidly decreases when the nitrogen concentration falls below a certain value. FIG. 3 is a graph showing the relationship between the ammoniacal nitrogen concentration in the nitrification part and the nitrification rate. As is clear from FIG. 3, the nitrification rate starts to decrease when the ammoniacal nitrogen concentration falls below 1 mg / l, It drops to about half of the maximum value at about 0.5 mg / l. That is, it can be seen that the ammoniacal nitrogen concentration must always be kept at 2 mg / l or more in order to continue the growth of nitrifying bacteria at the maximum rate and complete the start-up in as short a time as possible.
[0007]
By the way, at the time of start-up with an actual apparatus, in addition to shortening the start-up period, it is almost always necessary to increase the load while maintaining the treated water quality below the regulation value.
[0008]
Nitrifying bacteria increase in nitrification activity by about 20 to 40% per day due to their growth. On the other hand, when the load amount is adjusted manually as described above, the adjustment frequency is actually limited to once a day.
[0009]
For this reason, in the conventional method, after confirming that the ammonia nitrogen concentration in the treated water has decreased, the load is increased stepwise by an adjustment operation once a day. However, the amount of change in the load cannot be set larger as the safety of the treated water is taken into consideration, and the amount of change in the load cannot be set larger as the treated water quality is taken into consideration. In many cases, the ammonia nitrogen concentration decreased and the growth rate slowed down.
[0010]
The present invention solves the above-mentioned conventional problems, and when the nitrification tank is started up, it can be easily started up in a short period of time while maintaining the quality of the treated water, and nitrification can be performed well in response to load fluctuations. It is an object of the present invention to provide a nitrification apparatus capable of easily recovering the activity and automatically adjusting the load for starting up and recovering the activity and a method for operating the nitrification apparatus .
[0011]
[Means for Solving the Problems]
The nitrification apparatus of the present invention is a nitrification tank, means for measuring the ammonia nitrogen concentration of the nitrification water in the nitrification tank, and compares the measured ammonia nitrogen concentration with a preset ammonia nitrogen concentration. A control means for adjusting the nitrogen load of the nitrification tank by adding a nitrogen source or adjusting the flow rate of raw water so that the measured value is equal to or higher than the set value when the measured value is equal to or lower than the set value; It is characterized by.
The operation method of the nitrification apparatus of the present invention is the operation method of the nitrification apparatus of the present invention described above, and the measurement of the ammonia nitrogen concentration measuring means is performed when the nitrification apparatus is started up or when the nitrification activity is restored. The nitrogen concentration in the nitrification tank by comparing the value with a preset ammoniacal nitrogen concentration and adding the nitrogen source or adjusting the flow rate of the raw water by the control means so that the measured value is not less than the set value. The load amount is adjusted.
[0012]
[Action]
According to the nitrification apparatus and the operation method of the nitrification apparatus of the present invention, the ammonia nitrogen concentration set value for nitrification water is set in the range of, for example, 1 to 10 mg / l, and the nitrification water ammonia is set. When the measured value of the reactive nitrogen concentration becomes equal to or lower than the set value, the load can be adjusted quickly so that the measured value becomes equal to or higher than the set value. For this reason, it is possible to adjust the load before the nitrogen concentration decreases and the growth rate of nitrifying bacteria decreases, thereby maintaining the treated water quality and always allowing the nitrifying bacteria to grow at the maximum rate. Can do.
[0013]
Therefore, the start-up of the nitrification apparatus can be completed in a very short period of time, and the quality of the treated water during the start-up period can be suppressed below the regulation value.
[0014]
In the nitrification treatment apparatus and the operation method of the nitrification treatment apparatus of the present invention, since the activity recovery of the apparatus can be easily performed, when the load is reduced, the treatment is performed without adding a nitrogen source, resulting in a high load. An operation for recovery may be performed from two days ago, and the load can be easily increased.
[0015]
【Example】
Hereinafter, the present invention will be described more specifically with reference to the drawings.
[0016]
FIG. 1 is a system diagram showing an embodiment of the nitrification apparatus of the present invention.
[0017]
The nitrification apparatus of the present embodiment includes a
[0018]
In this embodiment, load adjustment is performed by injecting a nitrogen source such as ammonium sulfate in the nitrogen
[0019]
That is, the arithmetic device 4 compares the measured value of the ammonia
[0020]
As a result, the load can be adjusted before the nitrogen concentration decreases and the growth rate of the nitrifying bacteria decreases, and the nitrifying bacteria can always be grown at the maximum rate while maintaining the treated water quality.
[0021]
The nitrification apparatus shown in FIG. 1 is one embodiment of the present invention, and the present invention is not limited to the one shown in the drawings unless it exceeds the gist thereof.
[0022]
For example, the nitrification tank is not limited to the one that performs nitrification and denitrification, and only nitrification may be performed and a separate denitrification tank may be provided. Further, the nitrification tank may be of a floating system, a biological filtration system, or a fluidized bed system.
[0023]
Furthermore, the load adjustment is not limited to a method of adding a nitrogen source, and may be a method of adjusting the flow rate of raw water. That is, when the load amount is increased, the raw water inflow amount can be increased so that nitrogen remains in the treated water at a predetermined value or more. Usually, the method of adding a nitrogen source is effective when the nitrogen concentration of the raw water is low, and the method by adjusting the inflow amount of the raw water is effective when the nitrogen concentration of the raw water is high.
[0024]
In the present invention, the ammonia nitrogen concentration set value is appropriately determined depending on the regulation value of the treated water quality, the required startup efficiency, and the like, but is usually in the range of 1 to 10 mg / l.
[0025]
Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples.
[0026]
Example 1
Using the one-tank type nitrogen removing apparatus shown in FIG. 1, the apparatus stopped for about one month for regular inspection was started up.
[0027]
The design capacity of the apparatus was 0.7 kg-N / m 3 · day, and the nitrification rate at the time of start-up after stopping was about 0.4 kg-N / m 3 · day. The raw water nitrogen concentration was 60 mg / l, and the regulated value of treated water was TN 8 mg / l.
[0028]
After resuming the water flow, the ammonia nitrogen concentration of the treated water is measured semi-continuously every 15 minutes, and the ammonia water concentration of the treated water is set to 1.5 mg / l and once every hour by the arithmetic unit. The amount of nitrogen source added was adjusted by adding ammonium sulfate as a source.
[0029]
The state of recovery of nitrification performance at this time is shown in FIG.
[0030]
Comparative Example 1
In Example 1, the load amount was adjusted once a day after resuming water flow. The load amount was increased by 10% per day with respect to 0.4 kg-N / m 3 · day on the day of resuming water flow.
[0031]
The state of recovery of nitrification performance at this time is shown in FIG.
[0032]
As can be seen from FIG. 2, according to the present invention, the time required for start-up is drastically reduced to about half or less as compared with the case of the conventional manual operation.
[0033]
【The invention's effect】
As described above in detail, according to the nitrification treatment apparatus and the operation method of the nitrification treatment apparatus of the present invention, by automatically adjusting the nitrogen load based on the ammoniacal nitrogen concentration of the nitrification water,
(1) When the nitrification process is started or restarted, the start-up period of the apparatus can be greatly shortened.
(2) The treated water quality can be maintained below the regulation value even during the start-up period.
(3) Even when the raw water quality is changed and the nitrification activity is reduced while the treatment is continued, the activity can be recovered early while maintaining the treated water quality.
Such an excellent effect can be obtained, and an efficient nitrification treatment can be performed without requiring manual labor for load adjustment.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a nitrification apparatus of the present invention.
2 is a graph showing nitrification performance recovery states of Example 1 and Comparative Example 1. FIG.
FIG. 3 is a graph showing the relationship between the ammoniacal nitrogen concentration in the nitrification part and the nitrification rate.
[Explanation of symbols]
DESCRIPTION OF
Claims (2)
該硝化槽の硝化処理水のアンモニア性窒素濃度を測定する手段と、
測定されたアンモニア性窒素濃度を予め設定されたアンモニア性窒素濃度と比較し、測定値が設定値以下のときに、測定値が設定値以上となるように、窒素源の添加又は原水の流量の調整によって該硝化槽の窒素負荷量を調整する制御手段とを備えてなることを特徴とする硝化処理装置。A nitrification tank,
Means for measuring the ammonia nitrogen concentration in the nitrification water of the nitrification tank;
Compare the measured ammonia nitrogen concentration with the preset ammonia nitrogen concentration, and when the measured value is less than the set value , add the nitrogen source or the flow rate of the raw water so that the measured value is greater than the set value . And a control means for adjusting the nitrogen load of the nitrification tank by adjustment .
該硝化処理装置の立ち上げ又は硝化活性を回復させる際に、When starting up the nitrification apparatus or restoring nitrification activity,
前記アンモニア性窒素濃度測定手段の測定値と予め設定されたアンモニア性窒素濃度とを比較し、測定値が設定値以上となるように、前記制御手段によって、窒素源の添加又は原水の流量の調整をすることにより前記硝化槽の窒素負荷量を調整することを特徴とする硝化処理装置の運転方法。The measured value of the ammonia nitrogen concentration measuring means is compared with a preset ammonia nitrogen concentration, and the control means adds the nitrogen source or adjusts the flow rate of raw water so that the measured value is equal to or higher than the set value. The method of operating the nitrification apparatus is characterized in that the nitrogen load of the nitrification tank is adjusted by performing
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JP5789922B2 (en) * | 2010-07-02 | 2015-10-07 | 栗田工業株式会社 | Water treatment method and ultrapure water production method |
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