JP3269957B2 - How to remove nitrogen from wastewater - Google Patents
How to remove nitrogen from wastewaterInfo
- Publication number
- JP3269957B2 JP3269957B2 JP33067395A JP33067395A JP3269957B2 JP 3269957 B2 JP3269957 B2 JP 3269957B2 JP 33067395 A JP33067395 A JP 33067395A JP 33067395 A JP33067395 A JP 33067395A JP 3269957 B2 JP3269957 B2 JP 3269957B2
- Authority
- JP
- Japan
- Prior art keywords
- tank
- aerobic tank
- wastewater
- aerobic
- nitrification
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- 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
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Landscapes
- Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
- Biological Treatment Of Waste Water (AREA)
- Activated Sludge Processes (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、都市下水、有機性
産業廃水、汚泥処理水など、有機性汚濁物質と還元性窒
素化合物である有機性窒素やアンモニアなどの化合物を
含有する廃水から、窒素化合物を安定して効率的に除去
する廃水中の窒素除去方法に関する。The present invention relates to a method for producing nitrogen from wastewater containing organic pollutants and compounds such as organic nitrogen and ammonia, which are reducing nitrogen compounds, such as municipal sewage, organic industrial wastewater, and sludge treatment water. The present invention relates to a method for removing nitrogen from wastewater for stably and efficiently removing compounds.
【０００２】[0002]
【従来の技術】廃水中の窒素を除去する方法に関して、
物理的又は化学的な処理方法についても従来から研究さ
れてきたけれども、生物学的な処理方法がコスト的に有
利であるために現在のところ最も普及している処理方法
となっている。生物学的な窒素除去は、基本的には、好
気的条件のもとでの硝化細菌による還元性窒素、例え
ば、アンモニア性窒素（以下、ＮＨ4 −Ｎと略記する）
の酸化による硝酸性窒素（以下、ＮＯ3 −Ｎと略記す
る）の生成反応、すなわち硝化あるいは硝化反応（以下
の式（１）参照）と、嫌気性条件のもとでの通性嫌気性
細菌によるＮＯ3 −Ｎの還元による窒素ガス生成、すな
わち脱窒あるいは脱窒反応（以下の式（２）参照）と
の、組み合わせによって行われる。脱窒反応は溶存酸素
（以下、ＤＯと略記する）が存在しない条件下での通性
嫌気性細菌の呼吸であり、有機物などが炭素源（水素供
与体）として必要である。2. Description of the Related Art Regarding a method for removing nitrogen in wastewater,
Although physical or chemical treatment methods have been studied for some time, biological treatment methods are currently the most popular treatment methods because of their cost advantages. Biological nitrogen removal is basically performed by reducing nitrogen by nitrifying bacteria under aerobic conditions, for example, ammonia nitrogen (hereinafter abbreviated as NH 4 -N).
Reaction of nitrate nitrogen (hereinafter abbreviated as NO 3 -N) by oxidation of nitrocellulose, ie, nitrification or nitrification reaction (see the following formula (1)), and facultative anaerobic bacteria under anaerobic conditions Is performed in combination with nitrogen gas generation by reduction of NO 3 —N, that is, denitrification or a denitrification reaction (see the following formula (2)). The denitrification reaction is the respiration of facultative anaerobic bacteria under the condition that dissolved oxygen (hereinafter abbreviated as DO) does not exist, and requires an organic substance or the like as a carbon source (hydrogen donor).
【０００３】 ＮＨ4 −Ｎ → ＮＯ2 −Ｎ → ＮＯ3 −Ｎ（硝化反応）−−−（１） ＮＯ3 −Ｎ → ＮＯ2 −Ｎ → Ｎ2 （脱窒反応）−−−（２）[0003] NH 4 -N → NO 2 -N → NO 3 -N ( nitrification) --- (1) NO 3 -N → NO 2 -N → N 2 ( denitrification) --- (2)
【０００４】生物学的窒素除去プロセスについては、設
備面積の削減、水素供与体としての有機炭素源の削減、
水酸化ナトリウムなどのアルカリ剤の削減などを目的と
して各種のプロセスが提案されている。大別すると直列
方式、循環方式又はそれらの組合わせに分類される。直
列方式は、最初に硝化を行い、次に脱窒を行うもので、
脱窒に必要な水素供与体を外部から添加する場合と、添
加を行わずに活性汚泥の内生呼吸を利用する場合があ
る。[0004] Regarding the biological nitrogen removal process, reduction of equipment area, reduction of organic carbon source as hydrogen donor,
Various processes have been proposed for the purpose of reducing alkali agents such as sodium hydroxide. It can be broadly classified into a series system, a circulation system, or a combination thereof. In the series method, nitrification is first performed, and then denitrification is performed.
There is a case where a hydrogen donor necessary for denitrification is added from the outside, and a case where endogenous respiration of activated sludge is used without addition.
【０００５】一方、循環方式は、図３に示すように、最
初に脱窒を行い、次に硝化を行う硝化液循環方式、すな
わち、活性汚泥循環変法が広く検討されている。この方
法は、硝化液の循環により、硝化にともなって消費され
たアルカリが脱窒によってある程度回収できるという利
点がある。しかし、活性汚泥循環変法は、循環返送され
ない硝化液の一部が脱窒槽を経由せずに流出するため、
全窒素除去率（以下、Ｔ−Ｎ除去率と略記する）に限界
がある。また、図３に示すように、従来の活性汚泥循環
変法における好気槽は、同一槽内で有機物除去と硝化反
応の促進をはかっている。On the other hand, as a circulation system, as shown in FIG. 3, a nitrification solution circulation system in which denitrification is performed first and then nitrification is performed, that is, a modified activated sludge circulation method is widely studied. This method has the advantage that the alkali consumed by the nitrification can be recovered to some extent by denitrification by circulating the nitrification solution. However, in the activated sludge circulation modified method, a part of the nitrification liquid that is not returned in circulation flows out without passing through the denitrification tank,
There is a limit to the total nitrogen removal rate (hereinafter abbreviated as TN removal rate). In addition, as shown in FIG. 3, the aerobic tank in the conventional modified activated sludge circulation method is intended to remove organic substances and promote the nitrification reaction in the same tank.
【０００６】ところで、上記硝化反応において用いられ
る硝化細菌は、有機物を分解する活性汚泥と比較して増
殖速度が遅く、反応槽内で高濃度に維持することが困難
である。そこで各種の担体を反応槽に添加し、硝化細菌
を担体に付着させ、反応槽内で硝化細菌を高濃度に維持
し、反応効率を高めるさまざまな方法が提案されてい
る。例えば、特開平５−１００７８７号公報には、活性
汚泥が存在するリアクターの好気槽にポリウレタンスポ
ンジを添加して、都市下水中のＢＯＤ（生物学的酸素要
求量）／Ｎ比が４〜２０の有機性廃水をそのＢＯＤ／Ｎ
を維持しながら処理する生物学的方法が記載されてい
る。[0006] Nitrifying bacteria used in the nitrification reaction have a slower growth rate than activated sludge that decomposes organic substances, and it is difficult to maintain a high concentration in a reaction tank. Therefore, various methods have been proposed in which various carriers are added to a reaction vessel, nitrifying bacteria are adhered to the carrier, the nitrifying bacteria are maintained at a high concentration in the reaction vessel, and the reaction efficiency is improved. For example, JP-A-5-100787 discloses that a polyurethane sponge is added to an aerobic tank of a reactor in which activated sludge is present so that a BOD (biological oxygen demand) / N ratio in city sewage is 4 to 20. Organic wastewater to its BOD / N
Biological methods of treating while maintaining are described.
【０００７】[0007]
【発明が解決しようとする課題】従来の都市下水などを
生物学的に窒素除去するプロセスにおいては、都市下水
が硝化反応や脱窒反応を阻害する成分を含んでいること
が少なく、しかも、ＮＨ 4 −Ｎが２０〜５０mg／ｌ程度
である。したがって、活性汚泥循環変法などにより、下
水中のＮＨ4 −ＮをＮＯ3 −Ｎまで生物学的に酸化（硝
化反応）でき、また、生成したＮＯ3 −Ｎを窒素ガスま
で、脱窒することができる。しかし、硝化反応の速度
が、有機物の分解速度と比較して小さいため、反応槽の
滞留時間（Hydraulic Retention Time：以下、ＨＲＴと
略記する）が極めて長くなるという問題がある。例え
ば、都市下水のようにＮＨ4 −Ｎが２０〜５０mg／ｌの
場合でもＨＲＴが１２〜１６時間と長くなり、設備が大
型化せざるを得なくなる。[Problems to be solved by the present invention]
In the process of biological nitrogen removal, urban sewage
Contains components that inhibit nitrification and denitrification reactions
And NH Four-N is about 20 to 50 mg / l
It is. Therefore, the activated sludge circulation
NH in waterFour-N is NOThreeBiologically oxidized to -N
Reaction) and the generated NOThree−N to nitrogen gas
Then, it can be denitrified. However, the rate of nitrification reaction
Is smaller than the decomposition rate of organic matter,
Hydraulic Retention Time (HRT)
(Abbreviated) becomes extremely long. example
If it is NH like city sewageFour-N of 20 to 50 mg / l
Even in this case, the HRT is long, 12 to 16 hours, and the equipment is large.
It has to be typed.
【０００８】さらに、皮革工業、繊維工業、化学工業な
どの各種の産業廃水や汚泥処理水は、生物学的酸素要求
量（Biological Oxygen Demand：以下ＢＯＤと略記す
る）や化学的酸素要求量（Chemical Oxygen Demand：以
下ＣＯＤと略記する）で表されるような有機物の濃度が
高く、しかも、硝化反応や脱窒反応を阻害する芳香族系
有機物などのような成分を含むとともに、ＮＨ4 −Ｎを
５０mg／ｌ以上含むことが多い。したがって、硝化反応
の速度がさらに低下し、設備を一層大型化せざるを得な
いため、従来の活性汚泥循環変法などによって、窒素除
去を効率的に行うことはかなり困難となっている。以
下、硝化反応および脱窒反応に分けて、従来の生物学的
な窒素除去プロセスの課題を説明する。Further, various industrial wastewaters such as a leather industry, a textile industry, and a chemical industry, and sludge treated waters are used for biological oxygen demand (hereinafter abbreviated as BOD) and chemical oxygen demand (Chemical oxygen demand). Oxygen Demand: high concentration of organic material as represented by the following COD abbreviated), moreover, with include components, such as aromatic organic substances inhibit nitrification and denitrification, the NH 4 -N It often contains 50 mg / l or more. Therefore, the rate of the nitrification reaction is further reduced, and the equipment must be further enlarged. Therefore, it is considerably difficult to efficiently remove nitrogen by a conventional activated sludge circulation method or the like. Hereinafter, the problems of a conventional biological nitrogen removal process will be described separately into a nitrification reaction and a denitrification reaction.
【０００９】まず、硝化反応であるが、廃水中にＮＨ4
−Ｎが５０mg／ｌ以上含有されている場合には、ＮＨ4
−ＮからＮＯ3 −Ｎまでの反応が完結せず、亜硝酸性窒
素（以下、ＮＯ2 −Ｎと略記する）が蓄積する傾向が強
い。硝化細菌は、ＮＨ4 −ＮをＮＯ2 −Ｎまで酸化する
細菌群、例えばニトロゾモナス（Ｎｉｔｒｏｓｏｍｏｎ
ａｓ）などとＮＯ2 −ＮをＮＯ3 −Ｎまで酸化する細菌
群、例えば、ニトロバクター（Ｎｉｔｒｏｂａｃｔｏ
ｒ）などに大別されるが、ニトロバクターのほうがニト
ロゾモナスよりも増殖速度が大きいため、都市下水が対
象の場合には、ＮＯ2 −Ｎが蓄積されることはない。し
かし、ＤＯが不足したり、廃水中に硝化反応を阻害する
物質が存在する場合には、ニトロバクターの方がニトロ
ゾモナスより反応の阻害を受けやすいため、ニトロバク
ターの増殖速度が極端に低下する。このような場合、Ｎ
Ｏ2 −Ｎが蓄積しやすい。First, in the nitrification reaction, NH4 is contained in wastewater.Four
When -N is contained in an amount of 50 mg / l or more, NHFour
-N to NOThree-N is not complete and nitrite
Element (hereinafter NOTwo−N).
No. Nitrifying bacteria are NHFour-N is NOTwoOxidizes to -N
Bacterial groups such as Nitrozomonas (Nitrosomon
as) And NOTwo-N is NOThreeBacteria that oxidize to -N
Groups, such as Nitrobacter (Nitrobacto
r), But Nitrobacter is more
Because the growth rate is higher than that of Rozomonas, urban sewage
NO for elephantsTwo-N is not accumulated. I
However, DO becomes insufficient or inhibits nitrification reaction in wastewater
If the substance is present, the Nitrobactor
Nitrobac is more susceptible to reaction inhibition than Zomonas.
The growth rate of the tar becomes extremely low. In such a case, N
OTwo−N easily accumulates.
【００１０】反応槽で大量に蓄積したＮＯ2 −Ｎは、有
機物を分解する微生物や硝化細菌そのものの機能を阻害
する危険性がある。さらに、ＮＯ2 −Ｎの１mgがＣＯＤ
として１．１４mgとして計測されるため、ＮＯ2 −Ｎが
処理水中に蓄積すると、処理水中のＣＯＤが上昇する懸
念がある。このようなＮＯ2 −Ｎを生成する硝化反応を
防止し、ＮＯ3 −Ｎを生成する硝化反応を促進するため
には、反応槽へのＮＨ 4 −Ｎ負荷の低減、有機物負荷の
低減、反応槽の好気度制御、微生物滞留時間（Sludge R
etention Time ：以下、ＳＲＴと略記する）の増大、反
応槽のＨＲＴの増大などの方策が必要である。しかし、
ＳＲＴやＨＲＴの増大は設備の大型化を招いてしまう。
このことは、例えば、「Wat.Res., 1990年、Vol.24, N
o.3, pp.303〜312 」に指摘されている。[0010] NO accumulated in a large amount in the reaction tankTwo-N is Yes
Inhibits the function of microorganisms that degrade equipment and nitrifying bacteria themselves
There is a risk of doing. Furthermore, NOTwo1 mg of -N is COD
Is measured as 1.14 mg as NOTwo-N is
When accumulated in the treated water, the COD in the treated water may increase.
I have a mind. Such NOTwo-Nitration reaction to produce N
Prevent and NOThreeTo promote the nitrification reaction that produces -N
To the reactor Four-N load reduction, organic load reduction
Control, aerobic control of the reaction tank, microorganism retention time (Sludge R
etention Time (hereinafter abbreviated as SRT)
It is necessary to take measures such as increasing the HRT of the tank. But,
An increase in SRT or HRT causes an increase in the size of the equipment.
This is described, for example, in "Wat.Res., 1990, Vol. 24, N.
o.3, pp.303-312 ".
【００１１】ＮＨ4 −Ｎを８０mg／ｌ含有した人工廃水
を、ＤＯを０．５mg／ｌに維持し、反応槽のＨＲＴが４
日の条件で処理した場合、ＮＯ2 −Ｎが６０mg／ｌ蓄積
したとの報告であり、ＮＯ2 −Ｎを生成する酸化反応
は、ＤＯが低くても進行してしまうと結論づけている。
さらに、流入水のＣＯＤを変動させた実験により、有機
物負荷がＮＯ2 −Ｎの生成・蓄積に影響すると報告され
ている。このように、有機物の濃度が高く、さらにＮＨ
4 −Ｎを高濃度に含む廃水を対象として、活性汚泥循環
変法のような従来の浮遊型の活性汚泥を用いる生物学的
窒素除去プロセスによって処理を行う場合、ＮＯ2 −Ｎ
を蓄積する硝化反応が進行しやすいという課題が残され
ている。The artificial wastewater containing 80 mg / l of NH 4 —N was maintained at a DO of 0.5 mg / l, and the HRT of the reactor was 4 mg / l.
It was reported that when treated under day conditions, 60 mg / l of NO 2 -N was accumulated, and it was concluded that the oxidation reaction for producing NO 2 -N proceeds even when DO is low.
In addition, experiments in which the COD of the influent water was varied report that the organic matter load affects the generation and accumulation of NO 2 -N. Thus, the concentration of organic matter is high and NH
When treating wastewater containing a high concentration of 4- N by a biological nitrogen removal process using a conventional floating activated sludge such as a modified activated sludge circulation method, NO 2 -N
However, there remains a problem that a nitrification reaction that accumulates easily proceeds.
【００１２】ところで、従来から、上述の活性汚泥循環
変法において、ポリウレタンスポンジなどの浮遊担体を
好気槽に添加して硝化反応を効率的に行おうとする方法
がある。浮遊担体を好気槽に添加すると、硝化細菌が浮
遊担体表面に高濃度に維持できるとされ、この結果、硝
化反応速度が増し、硝化反応が生じやすい特徴があると
されている。しかし、廃水中の有機物の濃度が高い場合
には、硝化細菌ばかりでなく、浮遊担体の表面に有機物
を分解する細菌も同時に繁殖すると考えられる。有機物
を分解する細菌の増殖速度は、硝化細菌よりもはるかに
大きいことは周知の事実であり、浮遊担体添加による硝
化反応の促進効果は、廃水中の有機物の濃度が高い場合
には、かなり低下してしまう。また、廃水が皮革工業、
繊維工業、化学工業などの各種の産業廃水や汚泥処理水
の場合には、たとえ、浮遊担体を添加したとしても、阻
害成分の影響により、ニトロバクターの機能が低下し易
く、ＮＯ2 −Ｎが蓄積するという問題は残されている。Meanwhile, conventionally, in the above-mentioned modified activated sludge circulation method, there is a method in which a floating carrier such as a polyurethane sponge is added to an aerobic tank to efficiently perform a nitrification reaction. It is said that when a floating carrier is added to an aerobic tank, nitrifying bacteria can be maintained at a high concentration on the surface of the floating carrier, and as a result, the nitrification reaction speed is increased and the nitrification reaction is apt to occur. However, when the concentration of the organic matter in the wastewater is high, not only the nitrifying bacteria, but also the bacteria that decompose the organic matter on the surface of the floating carrier will be propagated at the same time. It is well known that the growth rate of bacteria that decompose organic matter is much higher than that of nitrifying bacteria, and the effect of accelerating the nitrification reaction by adding a floating carrier is significantly reduced when the concentration of organic matter in wastewater is high. Resulting in. In addition, wastewater is from the leather industry,
In the case of various industrial wastewater such as textile industry and chemical industry and sludge treated water, even if a suspended carrier is added, the function of nitrobacter is easily reduced due to the influence of inhibitory components, and NO 2 -N is reduced. The problem of accumulation remains.
【００１３】次に、脱窒反応であるが、都市下水中の有
機物やメタノールを炭素源として用いた場合には、反応
槽において、式（２）に示すようなＮＯ3 −ＮからＮ2
までの反応が完結し、ＮＯ2 −Ｎが蓄積することはまれ
である。しかし、脱窒反応の場合にも、廃水が皮革工
業、繊維工業、化学工業などの各種の産業廃水や汚泥処
理水の場合、硝化反応で述べた事項と同様の現象が生じ
る場合がある。すなわち、脱窒細菌もＮＯ3 −ＮをＮＯ
2 −Ｎまで還元する細菌群とＮＯ2 −ＮをＮ2 まで還元
する細菌群に大別されると考えられるが、ＮＯ2 −Ｎを
Ｎ2 まで還元する細菌群が有機物などの阻害によって機
能が低下し、脱窒槽内にＮＯ2 −Ｎが蓄積する現象がし
ばしば観察され、問題となっている。Next, in the case of a denitrification reaction, when organic matter or methanol in municipal sewage is used as a carbon source, NO 3 -N to N 2 as shown in the formula (2) is used in the reaction tank.
It is rare that the above reaction is completed and NO 2 -N accumulates. However, also in the case of the denitrification reaction, when the wastewater is various industrial wastewater such as a leather industry, a textile industry, and a chemical industry or sludge treatment water, a phenomenon similar to the matter described in the nitrification reaction may occur. That is, denitrifying bacteria also convert NO 3 -N to NO.
Until 2 -N bacteria group and NO 2 -N reducing considered to be divided into bacteria to reduced to N 2, but functions by inhibition of bacterial group include organic matter of reducing NO 2 -N to N 2 And the phenomenon that NO 2 —N accumulates in the denitrification tank is often observed and poses a problem.
【００１４】さらに、活性汚泥循環変法のような従来の
浮遊型の活性汚泥を用いる生物学的窒素除去プロセスの
好気槽の制御において、一般的には、ＤＯが管理指標と
して用いられることが多い。しかし、ＤＯは、廃水中に
阻害成分などがあり、微生物の活性が低下しやすい状況
においては有効な指標にはなりにくい。硝化反応はＤＯ
が高い程進行するなど、硝化反応とＤＯの相関性につい
ては数多くの報告がある。確かに、硝化反応にＤＯは必
要であり、硝化の反応速度に影響を与える。しかし、Ｄ
Ｏが高いからといって、硝化が進行しているとは限らな
い。すなわち、硝化細菌が阻害を受けた場合などは、硝
化細菌による酸素消費量が減少するため、逆にＤＯは上
昇する。したがって、ＤＯは硝化反応の進行度を示して
いるとはいえない。ただし、ＤＯは、硝化の反応速度、
すなわち、硝化細菌の増殖速度を維持するという観点か
らは重要であり、反応槽のＤＯを少なくとも２〜３mg／
ｌ以上に維持する必要がある。Furthermore, in controlling an aerobic tank in a biological nitrogen removal process using a conventional floating activated sludge such as a modified activated sludge circulation method, DO is generally used as a control index. Many. However, DO has little inhibitory component in wastewater, and it is hard to be an effective index in a situation where the activity of microorganisms tends to decrease. The nitrification reaction is DO
There are many reports on the correlation between the nitrification reaction and DO, such as progressing as the value increases. Certainly, DO is required for the nitrification reaction, which affects the nitrification reaction rate. But D
Just because O is high does not mean that nitrification is progressing. That is, for example, when the nitrifying bacteria are inhibited, DO increases because the oxygen consumption by the nitrifying bacteria decreases. Therefore, DO cannot be said to indicate the progress of the nitrification reaction. However, DO is a nitrification reaction rate,
That is, it is important from the viewpoint of maintaining the growth rate of nitrifying bacteria, and the DO of the reaction tank is at least 2-3 mg /
1 or more.
【００１５】本発明は、上述のような有機物と高濃度の
窒素を含有する廃水に対して、従来の活性汚泥循環変法
のような処理方法を適用した場合の上述の問題点を取り
除き、安定的、かつ、効率的に廃水中の窒素を除去する
方法を提供することを目的とする。[0015] The present invention eliminates the above-mentioned problems when a conventional treatment method such as a modified activated sludge circulation method is applied to wastewater containing organic matter and high concentration of nitrogen as described above, and is stable. It is an object of the present invention to provide a method for efficiently and efficiently removing nitrogen in wastewater.
【００１６】[0016]
【課題を解決するための手段】本発明に従って、嫌気槽
と好気槽とを設けて有機物と還元性窒素を含む廃水を循
環処理する活性汚泥循環変法において、 ａ）上記好気槽が好気槽（１）と好気槽（２）に、又は
多段に分けられており；そして ｂ）上記廃水が嫌気槽（３）内で脱窒され、上記好気槽
（１）内で有機物について酸化され、そして上記好気槽
（２）内で還元性窒素について硝化される、あるいは上
記好気槽が多段に分けられる場合には、上記廃水が有機
物について酸化される処理の後に、還元性窒素について
硝化される処理が行われ、その処理水を最終沈殿処理し
た後に、最終沈殿処理後の処理水中の還元性窒素を、好
気リアクター（５）により酸化処理した後に系外に排出
することを特徴とする、廃水中の窒素除去方法を提供す
る。好気槽（１）において、廃水中のＢＯＤで表示され
る有機物は十分に除去され、ついで好気槽（２）におい
て、還元性窒素が硝化処理される。すなわち、本発明
は、有機物酸化と硝化がそれぞれ独立の別個の好気槽
（１）と（２）の内でなされるので、有機物酸化と硝化
が同一の好気槽内で混在して行われる従来の処理方法に
おいて招来する有機物による硝化反応に及ぼす機能阻
害、特にＤＯの摂取競争が削減され、硝化反応が生じや
すい利点がある。また、沈殿処理後の流出水を、好気性
リアクターによって酸化処理する。これにより、硝化反
応の阻害成分を含む産業廃水などの場合、ＮＯ 2 −Ｎの
蓄積を完全に防止することができる。 In accordance with the present invention, in order to solve the problems] In the activated sludge circulation variant circulating process waste water containing organic substances and reducing nitrogen provided the anaerobic tank and the aerobic tank, a) the aerobic tank is good Divided into an air tank (1) and an aerobic tank (2) or in multi-stages; and b) the wastewater is denitrified in an anaerobic tank (3) and contains organic matter in the aerobic tank (1). Oxidized and nitrified in the aerobic tank (2) for reducing nitrogen, or, if the aerobic tank is divided into multiple stages, after the treatment in which the wastewater is oxidized for organic matter, Is treated for nitrification , and the treated water is subjected to final precipitation treatment.
After that, the reducing nitrogen in the treated water after the final precipitation
Exhausted after oxidation treatment by gas reactor (5)
A method for removing nitrogen from wastewater is provided. In the aerobic tank (1), organic substances indicated by BOD in the wastewater are sufficiently removed, and then, in the aerobic tank (2), the reducing nitrogen is nitrified. That is, according to the present invention, the organic matter oxidation and the nitrification are performed in independent and separate aerobic tanks (1) and (2), respectively, so that the organic matter oxidation and the nitrification are performed in the same aerobic tank. There is an advantage that the functional inhibition on the nitrification reaction due to the organic matter caused in the conventional treatment method, particularly the competition for ingestion of DO is reduced, and the nitrification reaction easily occurs. In addition, the effluent after the precipitation treatment is aerobic.
The oxidation treatment is performed by the reactor. As a result, nitrification
In the case of industrial wastewater containing a suitable inhibitory component, NO 2 -N
Accumulation can be completely prevented.
【００１７】さらに、好ましい本発明の態様において
は、切片が５〜１００mmの浮遊担体を好気槽（２）に５
〜４０容量％添加する。これにより硝化処理がさらに効
率よく行われる。また、本発明の態様においては、好ま
しくは嫌気槽内の廃水の酸化還元電位（Ａｇ／ＡｇＣｌ
基準）を、−１００〜−２００mVとし、また好ましくは
好気槽（２）内の廃水の酸化還元電位（Ａｇ／ＡｇＣｌ
基準）を、＋１００〜＋２００mVに維持し、また、好ま
しくは、好気性リアクターの充填担体を高炉水砕スラグ
を主原料とするサドル型セラミックスとし、また、好ま
しくは、好気性リアクター内の処理水の酸化還元電位
（Ａｇ／ＡｇＣｌ基準）を、＋１００〜＋２００mVに維
持する。Further, in a preferred embodiment of the present invention, a floating carrier having a section of 5 to 100 mm is placed in the aerobic tank (2) for 5 minutes.
Add ~ 40% by volume. Thereby, the nitrification treatment is performed more efficiently. In the embodiment of the present invention, preferably, the oxidation-reduction potential of the wastewater in the anaerobic tank (Ag / AgCl
Standard) is set to -100 to -200 mV, and preferably, the oxidation-reduction potential (Ag / AgClCl) of the wastewater in the aerobic tank (2).
Criterion) is maintained at +100 to +200 mV.
Details, the filling carrier aerobic reactor and saddle ceramics blast furnace slag as a main raw material, also, preferably, the redox potential of the treated water in the aerobic reactor (Ag / AgCl reference) + 100 Maintain at +200 mV.
【００１８】[0018]
【発明の実施の形態】以下、本発明について詳しく説明
する。図１に本発明に係る廃水中の窒素除去方法のフロ
ーを示す。図１に示すように、下水・廃水等の有機物を
含有する有機性廃水は、嫌気槽（３）、好気槽（１）、
好気槽（２）の順に処理され、最終沈殿池（４）によっ
て固液分離され、放流される。嫌気槽（３）において
は、好気槽（２）から循環された硝化液中のＮＯ3 −Ｎ
をＮ2 まで脱窒する。好気槽（１）においては有機物酸
化（除去）、好気槽（２）においては硝化の促進を図る
ものである。さらに、最終沈殿池（４）の後段の好気性
リアクター（５）は、ＮＯ3 −Ｎ生成型の硝化反応の促
進により処理水中のＮＯ2 −Ｎの残存を完全に防止する
ためのものである。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. FIG. 1 shows the flow of the method for removing nitrogen from wastewater according to the present invention. As shown in FIG. 1, organic wastewater containing organic matter such as sewage and wastewater is supplied to an anaerobic tank (3), an aerobic tank (1),
It is processed in the order of the aerobic tank (2), separated into solid and liquid by the final sedimentation tank (4), and discharged. In the anaerobic tank (3), NO 3 -N in the nitrification liquid circulated from the aerobic tank (2)
The denitrification to N 2. The aerobic tank (1) promotes oxidation (removal) of organic substances, and the aerobic tank (2) promotes nitrification. Further, the aerobic reactor (5) downstream of the final sedimentation basin (4) is for completely preventing the remaining NO 2 -N in the treated water by promoting the NO 3 -N generating type nitrification reaction. .
【００１９】まず、好気槽を好気槽（１）と好気槽
（２）に分けて処理する理由を説明する。好気槽（１）
で、有機物分解菌により廃水の有機物がほとんど分解さ
れれば、好気槽（２）での硝化細菌による硝化反応は、
有機物分解によるＤＯ消費によって抑制されることが少
ない。また、硝化細菌への阻害成分を含む廃水の場合、
阻害成分が直接硝化をおこす好気槽（２）に流入しない
ため、硝化への悪影響を弱めることができる。したがっ
て、好気槽を好気槽（１）と好気槽（２）に分けて処理
することによって、硝化反応の効率を格段に向上させる
ことができる。また、好気槽は２槽に限らず、多段に分
けてもかまわない。First, the reason why the processing is performed by dividing the aerobic tank into the aerobic tank (1) and the aerobic tank (2) will be described. Aerobic tank (1)
If the organic matter decomposing bacteria almost completely decompose the organic matter in the wastewater, the nitrification reaction by the nitrifying bacteria in the aerobic tank (2)
It is rarely suppressed by DO consumption due to organic matter decomposition. In the case of wastewater containing an inhibitory component for nitrifying bacteria,
Since the inhibitory component does not flow directly into the aerobic tank (2) that causes nitrification, the adverse effect on nitrification can be reduced. Therefore, by dividing the aerobic tank into the aerobic tank (1) and the aerobic tank (2), the efficiency of the nitrification reaction can be remarkably improved. The aerobic tank is not limited to two tanks, and may be divided into multiple stages.
【００２０】また、最終沈殿池（４）の後に、さらに、
図２に示す好気性リアクター（５）を設置することが好
ましい。すなわち、廃水が皮革工業、繊維工業、化学工
業などの各種の産業廃水や汚泥の処理水のようにＮＨ 4
−Ｎの濃度が高い場合には、好気槽（２）によっても、
ＮＨ 4 −ＮからＮＯ 3 −Ｎまでの反応が完全には完結せ
ず、ＮＯ 2 −Ｎが残存する場合もある。このような場
合、好気性リアクター（５）を設置すると、増殖速度の
遅いニトロバクターなどの硝化細菌を高濃度に固定化で
きるため、ＮＯ 2 −ＮをＮＯ 3 −Ｎまでの反応を効率的
に進めることができる。この結果、処理水中にＮＯ 2 −
Ｎが残存することはほとんど無くなる。さらに、好気槽
（２）に浮遊担体を添加することにより、好気槽（２）
での硝化効率を飛躍的に向上することができる。好気槽
（２）に流入する廃水には、好気槽（１）により有機物
がすでに分解されているため、有機物がほとんど残留し
ていないので、浮遊担体表面に硝化細菌を優先して増殖
させることができるためである。図２に示すように、本
発明の好気槽（２）に添加する浮遊担体（９）として
は、比重が１より小さいものであればよく、中空体、多
孔体、発泡体などがあるが、比表面積の大きな発泡体な
どが望ましい。また、材料としては、ポリエーテル系の
ポリウレタン、ポリエステル系のポリウレタンなど合成
樹脂などの有機系材料あるいはセラミックスなどの無機
系材料も使用することができる。なお、微生物の親和性
の観点から、用いるポリウレタンなどの担体は浸水性の
担体として吸水率が３％以上のものが望ましい。After the final sedimentation basin (4),
It is preferable to install the aerobic reactor (5) shown in FIG.
Good. In other words, wastewater is used in the leather, textile, and chemical industries.
NH as in the treated water of various industrial wastewater and sludge, such as work 4
When the concentration of -N is high, the aerobic tank (2)
Completely complete the reaction from NH 4 -N to NO 3 -N
Instead, NO 2 -N may remain. Such a place
If the aerobic reactor (5) is installed,
Immobilization of nitrifying bacteria such as slow nitrobacter at high concentration
The reaction from NO 2 -N to NO 3 -N is efficient
You can proceed to. As a result, NO 2 −
N hardly remains. Furthermore, by adding a floating carrier to the aerobic tank (2), the aerobic tank (2)
The nitrification efficiency can be dramatically improved. In the wastewater flowing into the aerobic tank (2), since the organic matter has already been decomposed by the aerobic tank (1), almost no organic matter remains. Therefore, nitrifying bacteria are preferentially grown on the surface of the floating carrier. This is because you can do it. As shown in FIG. 2, the floating carrier (9) to be added to the aerobic tank (2) of the present invention may have a specific gravity of less than 1, and includes a hollow body, a porous body, and a foam. And a foam having a large specific surface area. In addition, as a material, an organic material such as a synthetic resin such as a polyether-based polyurethane and a polyester-based polyurethane, or an inorganic material such as a ceramic can be used. In addition, from the viewpoint of the affinity of microorganisms, it is preferable that the carrier such as polyurethane used has a water absorption of 3% or more as a water-permeable carrier.
【００２１】また、ポリビニルアルコール、ポリアクリ
ルアミドなどの親水性合成高分子、ポリエチレングリコ
ールなどの親水性光硬化樹脂の発泡体を浮遊担体として
用いても構わない。担体は、径が小さい程、表面積が大
きくなる利点があり、反応速度が向上する。しかし、径
が小さくなる程、好気槽（２）から流出しやすく、ま
た、磨耗によって消失しやすい。したがって、その大き
さは、切片５〜１００mm程度であることが望ましい。切
片が５mm以下では、磨耗により流出しやすく、また、１
００mm以上では細菌が付着した場合、流動が困難となる
からである。Further, a foam of a hydrophilic synthetic polymer such as polyvinyl alcohol or polyacrylamide or a hydrophilic photocurable resin such as polyethylene glycol may be used as the floating carrier. The smaller the diameter of the carrier is, the larger the surface area is, and the reaction speed is improved. However, the smaller the diameter, the more easily it flows out of the aerobic tank (2), and the more easily it disappears due to wear. Therefore, the size is desirably about 5 to 100 mm. If the section is 5 mm or less, it easily flows out due to wear.
This is because if the size is more than 00 mm, the flow becomes difficult when bacteria adhere.
【００２２】さらに、好気槽（２）に添加する浮遊担体
の添加量は、浮遊担体の単位体積当たりの硝化速度をあ
らかじめ測定しておき、流入する廃水中のＮＨ4 −Ｎの
量および好気槽（２）の大きさなどを考慮して決めれば
よい。例えば、ポリウレタンフォームの場合、単位体積
あたりの硝化速度は、平均１００mgＮ／担体・ｌ・hr程
度である。したがって、好気槽（２）に５〜２０容量％
添加することにより、槽単位体積あたり５〜２０mgＮ／
槽・ｌ・hrの硝化速度が得られることになる。従来法の
活性汚泥循環変法の場合、槽単位体積あたりの硝化速度
は、ＭＬＳＳ（Mixed Liquor Suspended Solids)を２０
００mg／ｌとしても、２〜４mgＮ／槽・ｌ・hr程度であ
るから、硝化速度が５〜１０倍上昇する。しかし、浮遊
担体の添加量をあげるにつれ、浮遊担体のコストが上昇
し、また、好気槽（２）での担体の循環が困難となるた
め、４０容量％の添加が限度である。また、５容量％以
下の添加では顕著な効果を得ることは難しい。したがっ
て、浮遊担体の添加量は、１０〜２０容量％程度が最も
望ましい。Further, the amount of the suspended carrier to be added to the aerobic tank (2) can be determined by measuring the nitrification rate per unit volume of the suspended carrier in advance, and determining the amount of NH 4 —N in the wastewater flowing into the tank. The size may be determined in consideration of the size of the air tank (2). For example, in the case of a polyurethane foam, the nitrification rate per unit volume is about 100 mgN / carrier · l · hr on average. Therefore, 5-20% by volume in the aerobic tank (2)
By addition, 5 to 20 mg N /
A nitrification rate of 1 tank · l · hr is obtained. In the case of the modified activated sludge circulation method according to the conventional method, the nitrification rate per unit volume of the tank is MLSS (Mixed Liquor Suspended Solids).
Even at 00 mg / l, the nitrification rate is increased by a factor of 5 to 10 since it is about 2 to 4 mg N / tank · l · hr. However, as the added amount of the floating carrier increases, the cost of the floating carrier increases, and the circulation of the carrier in the aerobic tank (2) becomes difficult. Therefore, the addition of 40% by volume is limited. Further, it is difficult to obtain a remarkable effect by adding 5% by volume or less. Therefore, the addition amount of the floating carrier is most preferably about 10 to 20% by volume.
【００２３】次に好気槽における好気槽（１）と好気槽
（２）の容積比の決定方法を述べる。基本的には好気槽
（１）の容積は、単位ＭＬＳＳあたりのＢＯＤ除去速度
から、また、好気槽（２）の容積は、単位ＭＬＳＳあた
りの硝化速度または単位担体あたりの硝化速度から、槽
単位容積当りの速度を推定することにより求められる。
例えば、好気槽（１）のＭＬＳＳを２０００mg／ｌとし
た場合、通常、有機物除去のためのＢＯＤ容積負荷は
０．４kgＢＯＤ／kgＭＬＳＳ・ｄａｙ程度である。した
がって、単位時間あたりの好気槽（１）あたりのＢＯＤ
除去速度は、３３mgＢＯＤ／槽・ｌ・hrとなる。一方、
ポリウレタンを好気槽（２）に１０容量％添加した場
合、好気槽（２）の単位体積あたり硝化速度は、１０mg
Ｎ／槽・ｌ・hr程度である。Next, a method of determining the volume ratio between the aerobic tank (1) and the aerobic tank (2) in the aerobic tank will be described. Basically, the volume of the aerobic tank (1) is determined from the BOD removal rate per unit MLSS, and the volume of the aerobic tank (2) is determined from the nitrification rate per unit MLSS or the nitrification rate per unit carrier. It is determined by estimating the speed per unit volume of the tank.
For example, when the MLSS of the aerobic tank (1) is 2000 mg / l, the BOD volume load for removing organic substances is usually about 0.4 kgBOD / kgMLSS.day. Therefore, BOD per aerobic tank (1) per unit time
The removal rate is 33 mg BOD / tank · l · hr. on the other hand,
When 10% by volume of polyurethane is added to the aerobic tank (2), the nitrification rate per unit volume of the aerobic tank (2) is 10 mg.
N / tank · l · hr.
【００２４】この結果と廃水のＢＯＤ／Ｎ比から好気槽
（１）と好気槽（２）の容積比が計算される。例えば、
廃水のＢＯＤ／Ｎ比が５の廃水の場合、より具体的には
ＢＯＤが２００mg／ｌ、Ｔ−Ｎが４０mg／ｌの排水の場
合、好気槽（１）のＨＲＴは６時間、好気槽（２）のＨ
ＲＴは４時間となり、総ＨＲＴは１０時間、好気槽
（１）と好気槽（２）の容積比は１．５となる。より正
確には、好気槽（１）の前段の嫌気槽においてＢＯＤが
分解することを考慮し、好気槽（１）と好気槽（２）の
容積比を、好気槽に流入する廃水のＢＯＤ／Ｎ比で決定
してもよい。このような廃水の場合、従来の活性汚泥循
環変法では、総ＨＲＴは２０時間程度必要と考えられる
ため、反応槽の容積を５０％削減できることになる。From this result and the BOD / N ratio of the waste water, the volume ratio between the aerobic tank (1) and the aerobic tank (2) is calculated. For example,
In the case of wastewater with a BOD / N ratio of 5, the BRT is 200 mg / l and the TN is 40 mg / l wastewater, the HRT of the aerobic tank (1) is 6 hours, aerobic. H in tank (2)
The RT is 4 hours, the total HRT is 10 hours, and the volume ratio between the aerobic tank (1) and the aerobic tank (2) is 1.5. More precisely, taking into account that BOD is decomposed in the anaerobic tank preceding the aerobic tank (1), the volume ratio of the aerobic tank (1) and the aerobic tank (2) flows into the aerobic tank. It may be determined by the BOD / N ratio of the wastewater. In the case of such wastewater, in the conventional activated sludge circulation modified method, it is considered that the total HRT is required about 20 hours, so that the volume of the reaction tank can be reduced by 50%.
【００２５】好気槽（２）の出口付近に、例えば、図２
に示すステンレス製の籠などの浮遊担体（９）の保持装
置（８）を設置し、この内部にポリウレタンなどの担体
を添加してもよい。担体分離装置としては、ウエッジワ
イヤスクリーンを好気槽内部に設置し、処理水のみをと
りだすことが多いが、この方式では、ポリウレタンが劣
化した場合などの浮遊担体の交換が困難であるととも
に、循環ポンプなどを設置した場合、循環ポンプのスト
レーナーに目づまりが生じやすいという問題がある。担
体分離装置では無く、担体保持装置（８）を設置すれ
ば、このような問題もなく、また、浮遊担体の添加量の
制御も容易である利点がある。したがって、好気槽
（２）の内部の出口付近に担体保持装置を設置すること
が望ましい。In the vicinity of the outlet of the aerobic tank (2), for example, FIG.
A holding device (8) for a floating carrier (9) such as a basket made of stainless steel as shown in (1) may be provided, and a carrier such as polyurethane may be added to the inside thereof. As a carrier separation device, a wedge wire screen is often installed inside an aerobic tank and only treated water is taken out.However, in this method, it is difficult to exchange floating carriers when polyurethane is degraded, etc. When a pump or the like is installed, there is a problem that the strainer of the circulation pump is easily clogged. If the carrier holding device (8) is installed instead of the carrier separation device, there is an advantage that such a problem does not occur and the addition amount of the suspended carrier can be easily controlled. Therefore, it is desirable to install a carrier holding device near the outlet inside the aerobic tank (2).
【００２６】[0026]
【００２７】好気性リアクターは、一般に充填担体を充
填した充填層（２８）とこの充填層に空気を供給する散
気装置（２９）からなる。好気性リアクター（５）の充
填担体としては、浮遊担体、高炉水砕スラグを主原料と
したサドル型セラミックス、シリカ−アルミナ系のセラ
ミックス、プラスチックス、アンスラサイト、砂、活性
炭、高炉水砕スラグなどがある。特に、特公平２−００
６５８９号公報にあるような高炉水砕スラグを主原料と
したサドル型セラミックスを担体として用いた好気性固
定床型リアクターは、セラミックスが多孔質で表面積が
大きく、硝化細菌が固定化されやすく、また、サドル型
という形状のため、リアクター内の気液混合性能が優れ
ており、最終沈殿池（４）の後に設置する好気性リアク
ター（５）として最も望ましいものである。硝化細菌は
水温の影響を受けやすく、水温が低下すると処理能力が
低下しやすいがこの好気性固定床型リアクターは、水温
が５〜１０℃のような条件下でも、１０mg・Ｎ／槽・ｌ
・hr以上の硝化能力を有している。また、汚泥の引き抜
き管理、ＳＲＴ管理、汚泥の返送などの必要が無く、仕
上げ用の好気性リアクター（５）として最も望ましいも
のである。The aerobic reactor generally comprises a packed bed (28) filled with a packed carrier and an air diffuser (29) for supplying air to the packed bed. Packing carriers for the aerobic reactor (5) include floating carriers, saddle-type ceramics mainly made of granulated blast furnace slag, silica-alumina ceramics, plastics, anthracite, sand, activated carbon, granulated blast furnace slag, etc. There is. In particular,
An aerobic fixed-bed reactor using a saddle-type ceramic as a carrier, which is mainly made of granulated blast-furnace slag as disclosed in No. 6589, has a large ceramic surface area and a large surface area, and nitrifying bacteria are easily immobilized. Because of its saddle shape, it has excellent gas-liquid mixing performance in the reactor, and is most desirable as an aerobic reactor (5) installed after the final sedimentation basin (4). Nitrifying bacteria are susceptible to the effect of water temperature, and if the water temperature decreases, the processing capacity tends to decrease. However, this aerobic fixed-bed reactor has a capacity of 10 mg · N / tank · l even under conditions where the water temperature is 5 to 10 ° C.
・ Has nitrification capacity of hr or more. Further, there is no need for sludge pull-out management, SRT management, sludge return, etc., and this is the most desirable as an aerobic reactor (5) for finishing.
【００２８】さらに、還元性窒素化合物の酸化を行う好
気槽（２）、および、好気性リアクター（５）の酸化還
元電位（Ａｇ／ＡｇＣｌ基準）が＋１００〜＋２００mV
に維持されるように、好気槽（２）および好気性リアク
ター（５）へ散気装置（２９）からの、空気および／ま
たは酸素富化空気および／または酸素の吹き込み量を制
御することにより、硝化反応を安定して推進することが
できる。酸化還元電位は、廃水の有機物やＮＨ4 −Ｎな
どの還元性窒素化合物によって低下し、また、逆に、Ｎ
Ｏ3 −ＮやＤＯによって上昇する傾向がある。このよう
に、硝化反応の進行と酸化還元電位の値は密接な関係が
あり、酸化還元電位が＋１００〜＋２００mVに上昇する
と、窒素はＮＨ4 −Ｎでは無く、ＮＯ2 −ＮやＮＯ3 −
Ｎの形態となっている。さらに、ＤＯ管理を併用し、Ｄ
Ｏを３mg／ｌ以上に保つように管理してもよい。ＤＯ管
理を併用すれば、硝化性能が低下した場合に、ＤＯ不足
による性能低下では無いことが明らかになり、原因究明
やその後の対策が容易となる。The oxidation-reduction potential (based on Ag / AgCl) of the aerobic tank (2) for oxidizing the reducing nitrogen compound and the aerobic reactor (5) is +100 to +200 mV.
By controlling the blowing rate of air and / or oxygen-enriched air and / or oxygen from the air diffuser (29) to the aerobic tank (2) and the aerobic reactor (5) so that In addition, the nitrification reaction can be stably promoted. The oxidation-reduction potential is lowered by the organic matter of the wastewater or a reducing nitrogen compound such as NH 4 —N, and
O 3 —N and DO tend to increase. As described above, the progress of the nitrification reaction is closely related to the value of the oxidation-reduction potential. When the oxidation-reduction potential increases to +100 to +200 mV, nitrogen is not NH 4 —N, but NO 2 —N or NO 3 −
N form. Furthermore, using DO management together, D
O may be controlled so as to be maintained at 3 mg / l or more. If the DO management is used together, it becomes clear that when the nitrification performance is lowered, it is not the performance deterioration due to the shortage of DO, and the investigation of the cause and the subsequent measures are facilitated.
【００２９】また、完全に処理水の窒素を除去するため
には、好気性リアクターの後段に、メタノールなどの水
素供与体を添加する嫌気性リアクターおよび残存する水
素供与体を分解する再曝気槽を設置すればさらに好まし
い。好気槽（２）で硝化された硝化液は、嫌気槽（３）
に返送されて循環される。嫌気槽（３）は、好気槽
（２）の硝化液中に含まれるＮＯ2 −ＮやＮＯ3 −Ｎを
窒素ガスまで生物学的に効率的に還元する作用を有して
いる。In order to completely remove nitrogen from the treated water, an anaerobic reactor to which a hydrogen donor such as methanol is added and a re-aeration tank for decomposing the remaining hydrogen donor are provided downstream of the aerobic reactor. It is more preferable to install them. The nitrified liquid nitrified in the aerobic tank (2) is supplied to the anaerobic tank (3).
Returned to and circulated. The anaerobic tank (3) has a function of biologically and efficiently reducing NO 2 -N and NO 3 -N contained in the nitrification liquid of the aerobic tank (2) to nitrogen gas.
【００３０】嫌気槽（３）には通常、担体は添加しない
が、効率向上の目的で、浮遊担体、プラスチックス、ア
ンスラサイト、砂、活性炭、高炉水砕スラグなどのいず
れかを添加、または、特公平２−００６５８９号公報に
あるような高炉水砕スラグを主原料としたサドル型セラ
ミックスやシリカ−アルミナ系粘土を主原料としたセラ
ミックスなどのいずれかを充填してもよい。このような
担体に脱窒細菌を高濃度に維持することにより、脱窒反
応を効率的に進めることができる。嫌気槽（３）におい
て、脱窒細菌の活動を良好に保つためには、嫌気槽
（３）の酸化還元電位を−１００〜−２００mV（Ａｇ／
ＡｇＣｌ基準）に維持することが重要である。Usually, no carrier is added to the anaerobic tank (3), but for the purpose of improving efficiency, any one of a floating carrier, plastics, anthracite, sand, activated carbon, granulated blast furnace slag, etc. is added, or Any of saddle-type ceramics mainly made of granulated blast furnace slag and ceramics mainly made of silica-alumina clay as disclosed in Japanese Patent Publication No. 2-006589 may be filled. By maintaining a high concentration of denitrifying bacteria in such a carrier, the denitrification reaction can proceed efficiently. In order to keep the activity of the denitrifying bacteria in the anaerobic tank (3) good, the oxidation-reduction potential of the anaerobic tank (3) should be -100 to -200 mV (Ag /
(AgCl standard) is important.
【００３１】酸化還元電位は、廃水の有機物やＮＨ4 −
Ｎなどの還元性窒素化合物によって低下し、また、逆
に、ＮＯ3 −ＮやＤＯによって上昇する傾向がある。こ
のため、嫌気槽の酸化還元電位管理は、以下の方法で行
う。まず、酸化還元電位が−１００mV以上になると、脱
窒速度が低下し、処理性能が悪化しやすい。また、逆に
嫌気槽の酸化還元電位が低下しすぎると、メタンガスや
硫化水素ガスなどの発生しやすく、脱窒細菌の機能が阻
害される場合がある。したがって、嫌気槽の酸化還元電
位は、−１００〜−２００mV（Ａｇ／ＡｇＣｌ基準）に
維持することが望ましい。The oxidation-reduction potential depends on the organic matter and NH 4 −
It tends to be reduced by reducing nitrogen compounds such as N, and conversely, increased by NO 3 —N and DO. For this reason, the oxidation-reduction potential management of the anaerobic tank is performed by the following method. First, when the oxidation-reduction potential is -100 mV or more, the denitrification rate decreases, and the processing performance tends to deteriorate. Conversely, if the oxidation-reduction potential of the anaerobic tank is too low, methane gas, hydrogen sulfide gas, and the like are likely to be generated, and the function of the denitrifying bacteria may be hindered. Therefore, it is desirable to maintain the oxidation-reduction potential of the anaerobic tank at -100 to -200 mV (based on Ag / AgCl).
【００３２】嫌気槽の酸化還元電位を制御するため、酸
化還元電位が−２００mV以下になると空気をブロアで供
給し、−１００mV以上になると、メタノール、イソプロ
ピルアルコール、酢酸などの水素供与体を添加する装置
を設置することが望ましい。窒素を含まない廃液を用い
てもかまわない。一般に、都市下水の場合は、雨水など
の流入により嫌気槽の酸化還元電位が上昇しやすく、ま
た、有機物を多量に含む産業廃水の場合は、嫌気槽の酸
化還元電位が低下しやすい傾向がある。In order to control the oxidation-reduction potential of the anaerobic tank, when the oxidation-reduction potential becomes -200 mV or less, air is supplied by a blower, and when it becomes -100 mV or more, a hydrogen donor such as methanol, isopropyl alcohol or acetic acid is added. It is desirable to install equipment. A waste liquid containing no nitrogen may be used. In general, in the case of municipal sewage, the oxidation-reduction potential of the anaerobic tank tends to increase due to inflow of rainwater and the like, and in the case of industrial wastewater containing a large amount of organic substances, the oxidation-reduction potential of the anaerobic tank tends to decrease. .
【００３３】[0033]
【００３４】[0034]
【００３５】[0035]
【００３６】[0036]
【００３７】[0037]
【００３８】＜実施例＞ 皮革工場廃水を用いた現場実験処理を行った。実験処理
の対象とした皮革工場廃水は、前処理の沈殿操作でＳＳ
を除去したものである。ＢＯＤは平均６００mg／ｌ、Ｃ
ＯＤMnは平均４００mg／ｌ、Ｔ−Ｎが平均１５０mg／ｌ
であった。また、水温は、冬場でも１２℃以上に維持さ
れていた。図２に方法の概要を示す。好気槽（２）に、
Ｔ−Ｎがかなり高いことから、硝化細菌の付着担体とし
て、２０mm角のポリウレタンを２０容量％添加した。な
お、ポリウレタンは、５mmメッシュのステンレス製の担
体保持装置（８）内で流動させた。好気槽（２）から嫌
気槽（３）への循環量は、廃水に対し２５０％、最終沈
殿池（４）から嫌気槽（３）への返送汚泥量は廃水に対
し５０％とした。また、好気槽（１）、嫌気槽（３）の
ＭＬＳＳ管理値は５０００mg／ｌとした。<Example> An on-site experimental treatment was performed using leather factory wastewater. The wastewater from the leather factory, which was the subject of the experimental treatment,
Is removed. BOD averaged 600mg / l, C
OD Mn average 400 mg / l, TN average 150 mg / l
Met. Further, the water temperature was maintained at 12 ° C. or higher even in winter. FIG. 2 shows an outline of the method. In the aerobic tank (2),
Since the TN is considerably high, 20% by volume of 20 mm square polyurethane was added as an attachment carrier for nitrifying bacteria. The polyurethane was flowed in a 5 mm mesh stainless steel carrier holding device (8). The amount of circulation from the aerobic tank (2) to the anaerobic tank (3) was 250% based on the wastewater, and the amount of sludge returned from the final sedimentation tank (4) to the anaerobic tank (3) was 50% based on the wastewater. The MLSS control value of the aerobic tank (1) and the anaerobic tank (3) was 5000 mg / l.
【００３９】好気槽（１）と好気槽（２）の容量は以下
の方法で決定した。ＭＬＳＳ管理値が５０００mg／ｌの
場合、ＢＯＤ除去速度は、８３mg・ＢＯＤ／槽・ｌ・hr
程度、また、硝化速度は２０mg・Ｎ／槽・ｌ・hr程度で
あることから、ＢＯＤ除去速度／硝化速度比は４であ
る。さらに、下水のＢＯＤ／Ｔ−Ｎ比は、４であること
から、好気槽（１）／好気槽（２）の容量比は４／４＝
１となる。具体的には好気槽（１）のＨＲＴは７．２時
間、好気槽（２）のＨＲＴを７．２時間とした。さら
に、脱窒速度は１mgＮ／ｇ・ＭＬＳＳ・hr程度であるか
ら、嫌気槽（３）の容量あたりの脱窒速度は、５mgＮ／
槽・ｌ・hrである。返送汚泥量を加えた総循環量Ｒは、
３００％であるから、好気槽（２）出口の（ＮＯ2 −Ｎ
＋ ＮＯ3−Ｎ）濃度は、１５０mg × １／（１＋
３）の式で推定され、３７．５mg／ｌ程度となる。した
がって、嫌気槽（３）のＨＲＴを７．５時間に設定し
た。したがって、本実験の嫌気槽（３）、好気槽
（１）、および好気槽（２）の総ＨＲＴは、２２時間で
ある。また、好気性リアクター（５）のＨＲＴは、水温
で１２℃以上に維持されていたことから、硝化速度を１
０mg・Ｎ／槽・ｌ・hr程度とし、好気槽（２）出口の
（ＮＯ2 −Ｎ ＋ ＮＯ3 −Ｎ）濃度が、３７．５mg／
ｌ程度と推定されることから４時間に設定した。The capacities of the aerobic tanks (1) and (2) were determined by the following method. When the MLSS control value is 5000 mg / l, the BOD removal rate is 83 mg · BOD / tank · l · hr.
Since the nitrification rate is about 20 mg · N / tank · l · hr, the BOD removal rate / nitrification rate ratio is 4. Furthermore, since the sewage BOD / TN ratio is 4, the capacity ratio of the aerobic tank (1) / aerobic tank (2) is 4/4 =
It becomes 1. Specifically, the HRT of the aerobic tank (1) was set to 7.2 hours, and the HRT of the aerobic tank (2) was set to 7.2 hours. Further, since the denitrification rate is about 1 mgN / g · MLSS · hr, the denitrification rate per capacity of the anaerobic tank (3) is 5 mgN / g.
The tank is lhr. The total circulation amount R including the returned sludge amount is
Since it is 300%, (NO 2 -N
+ NO 3 -N) concentration is 150 mg × 1 / (1+
It is estimated by the formula of 3), and it is about 37.5 mg / l. Therefore, the HRT of the anaerobic tank (3) was set to 7.5 hours. Therefore, the total HRT of the anaerobic tank (3), the aerobic tank (1), and the aerobic tank (2) in this experiment is 22 hours. Further, since the HRT of the aerobic reactor (5) was maintained at 12 ° C. or higher at the water temperature, the nitrification rate was 1
0 mg · N / tank · l · hr, and the (NO 2 −N + NO 3 −N) concentration at the outlet of the aerobic tank (2) was 37.5 mg /
It was set to 4 hours because it is estimated to be about l.
【００４０】嫌気槽（３）の酸化還元電位は、酸化還元
電位が低下しやすいので、酸化還元電位制御装置を用い
て、ブロア（１８）から散気装置（２９）を介して槽内
に空気を供給する方法により、−２００mVに制御した。
また、好気槽（１）の酸化還元電位は、酸化還元電位制
御装置（１３）によって、ブロア（１９）から酸素を供
給して＋５０mVに制御した。さらに、好気槽（２）、お
よび、好気性リアクター（５）の酸化還元電位は、酸化
還元電位制御装置（１５）および（１７）によってブロ
ア（２０）および（２１）から散気装置（２９）を介し
て槽内に酸素を供給して＋１５０mVに制御した。１〜３
月の冬期の低水温期の実験結果を表２に示す。表２の結
果より、本法の処理水（２６）は、ＢＯＤが１０mg／ｌ
以下、ＣＯＤMnが５０mg／ｌ以下、Ｔ−Ｎが４０mg／ｌ
以下、ＮＯ2 −Ｎは未検出であり、良好な結果が得られ
た。Since the oxidation-reduction potential of the anaerobic tank (3) tends to decrease, the oxidation-reduction potential control device is used to supply air from the blower (18) into the tank via the air diffuser (29). Was controlled to -200 mV by the method of supplying.
The oxidation-reduction potential of the aerobic tank (1) was controlled to +50 mV by supplying oxygen from the blower (19) by the oxidation-reduction potential controller (13). Further, the oxidation-reduction potential of the aerobic tank (2) and the aerobic reactor (5) is increased from the blowers (20) and (21) by the oxidation-reduction potential control devices (15) and (17). ) Was supplied to the inside of the tank to control to +150 mV. 1-3
Table 2 shows the experimental results of the lunar winter season. From the results in Table 2, the treated water (26) of this method has a BOD of 10 mg / l.
Hereinafter, COD Mn is 50 mg / l or less, and TN is 40 mg / l.
Hereinafter, NO 2 -N was not detected, and good results were obtained.
【００４１】この実験結果から、本法は、冬季の低水温
期においても、総処理時間が２６時間程度で、皮革廃水
中の有機物と窒素化合物を効率的に除去でき、しかも、
ＮＯ 2 −Ｎが蓄積しないため、処理水質が安定すること
が明らかになった。From the results of this experiment, the present method can be applied to low water temperature in winter.
The total treatment time is about 26 hours, and leather wastewater
Organic substances and nitrogen compounds can be efficiently removed, and
NO Two-N does not accumulate, so treated water quality is stable
Was revealed.
【００４２】[0042]
【表２】 [Table 2]
【００４３】[0043]
【発明の効果】従来の活性汚泥循環変法では、有機物と
アンモニア性化合物等の還元性窒素化合物を含有する廃
水の処理において、硝化速度が遅く設備が過大となる問
題点がある。また、産業廃水の場合には、硝化・脱窒の
阻害成分を含むことがあるため、設備がさらに大きくな
るとともに、処理水中にＣＯＤ源となるＮＯ2 −Ｎが蓄
積しやすく、この制御が問題となる。本発明は、好気槽
が有機物除去を行う好気槽（１）と硝化を行う好気槽
（２）からなり、好気槽（２）に浮遊担体を添加し、酸
化還元電位制御を行っているので、従来の活性汚泥循環
変法と比較して、硝化速度が大きく、アンモニア性窒素
等の還元性窒素化合物を効率的に除去することができ、
設備を小型化でき、好気性リアクター（５）を設置し、
ＮＯ2 −Ｎがほぼ完全に酸化できる結果、処理水質が向
上する。According to the conventional activated sludge circulation modification method, there is a problem that the nitrification rate is slow and the equipment becomes excessively large in the treatment of wastewater containing organic substances and reducing nitrogen compounds such as ammoniacal compounds. Further, in the case of industrial wastewater, since components that inhibit nitrification and denitrification may be contained, the size of the equipment is further increased, and NO 2 -N, which is a COD source, easily accumulates in the treated water. Becomes In the present invention, the aerobic tank comprises an aerobic tank (1) for removing organic substances and an aerobic tank (2) for nitrification, and a floating carrier is added to the aerobic tank (2) to control the oxidation-reduction potential. As compared with the conventional activated sludge circulation modified method, the nitrification rate is large, and it is possible to efficiently remove reducing nitrogen compounds such as ammonia nitrogen.
Facilities can in miniaturization, established the aerobic reactor (5),
As a result of NO 2 -N being almost completely oxidized, the quality of treated water is improved.
【００４４】[0044]
【図１】本発明に係る廃水中の窒素除去方法のフローを
示す図である。FIG. 1 is a diagram showing a flow of a method for removing nitrogen from wastewater according to the present invention.
【図２】本発明の実施例を示す図である。FIG. 2 is a diagram showing an embodiment of the present invention.
【図３】従来の活性汚泥循環変法による廃水処理のフロ
ーを示す図である。FIG. 3 is a diagram showing a flow of wastewater treatment by a conventional activated sludge circulation modified method.
１…好気槽（１） ２…好気槽（２）（硝化槽） ３…嫌気槽 ４…最終沈殿池 ５…好気性リアクター ６…汚泥返送ポンプ ７…硝化液循環ポンプ ８…浮遊担体保持装置 ９…浮遊担体 １０…酸化還元電位センサー １１…酸化還元電位制御装置 １２…酸化還元電位センサー １３…酸化還元電位制御装置 １４…酸化還元電位センサー １５…酸化還元電位制御装置 １６…酸化還元電位センサー １７…酸化還元電位制御装置 １８…ブロア １９…ブロア ２０…ブロア ２１…ブロア ２２…水中攪拌機 ２３…メタノール添加ポンプ ２４…メタノールタンク ２５…都市下水または産業廃水 ２６…処理水 ２７…処理水 ２８…充填層 ２９…散気装置 DESCRIPTION OF SYMBOLS 1 ... Aerobic tank (1) 2 ... Aerobic tank (2) (nitrification tank) 3 ... Anaerobic tank 4 ... Final sedimentation tank 5 ... Aerobic reactor 6 ... Sludge return pump 7 ... Nitrification liquid circulation pump 8 ... Floating carrier holding Device 9: Floating carrier 10: Redox potential sensor 11: Redox potential control device 12: Redox potential sensor 13: Redox potential control device 14: Redox potential sensor 15: Redox potential control device 16: Redox potential sensor 17 ... Redox potential control device 18 ... Blower 19 ... Blower 20 ... Blower 21 ... Blower 22 ... Underwater stirrer 23 ... Methanol addition pump 24 ... Methanol tank 25 ... Municipal sewage or industrial wastewater 26 ... Treated water 27 ... Treated water 28 ... Filling Layer 29: diffuser
フロントページの続き (56)参考文献 特開 平２−139094（ＪＰ，Ａ) 特開 昭60−54792（ＪＰ，Ａ) 特開 昭64−51197（ＪＰ，Ａ) 特開 平６−31297（ＪＰ，Ａ) 特開 平７−39899（ＪＰ，Ａ) 特開 平７−100485（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C02F 3/34 101 C02F 3/30 Continuation of front page (56) References JP-A-2-139094 (JP, A) JP-A-60-54792 (JP, A) JP-A-64-51197 (JP, A) JP-A-6-31297 (JP, A) , A) JP-A-7-39899 (JP, A) JP-A-7-100485 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C02F 3/34 101 C02F 3/30
Claims (7)
性窒素を含む廃水を循環処理する活性汚泥循環変法にお
いて、 ａ）上記好気槽が好気槽（１）と好気槽（２）に、又は
多段に分けられており；そして ｂ）上記廃水が嫌気槽（３）内で脱窒され、上記好気槽
（１）内で有機物について酸化され、そして上記好気槽
（２）内で還元性窒素について硝化される、あるいは上
記好気槽が多段に分けられる場合には、上記廃水が有機
物について酸化される処理の後に、還元性窒素について
硝化される処理が行われ、その処理水を最終沈殿処理し
た後に、最終沈殿処理後の処理水中の還元性窒素を、好
気リアクター（５）により酸化処理した後に系外に排出
することを特徴とする、廃水中の窒素除去方法。1. An activated sludge circulating method in which an anaerobic tank and an aerobic tank are provided to circulate wastewater containing organic matter and reducing nitrogen. A) The aerobic tank comprises an aerobic tank (1) and an aerobic tank. B) the wastewater is denitrified in an anaerobic tank (3), oxidized for organic matter in the aerobic tank (1), and the aerobic tank (2) In the case where the reducing nitrogen is nitrified in the above or the aerobic tank is divided into multiple stages, after the above-mentioned treatment in which the wastewater is oxidized with respect to the organic matter, the treatment in which the reducing nitrogen is nitrified is performed. , The final treatment of the treated water
After that, the reducing nitrogen in the treated water after the final precipitation
Exhausted after oxidation treatment by gas reactor (5)
A method for removing nitrogen from wastewater.
に、切片が５〜１００mmである浮遊担体を５〜４０容量
％添加することを特徴とする請求項１に記載の方法。2. The method according to claim 1, wherein 5 to 40% by volume of a floating carrier having a section of 5 to 100 mm is added to the aerobic tank (2) or the aerobic tank in which nitrification is performed. .
ことを特徴とする請求項２に記載の方法。3. The method according to claim 2, wherein the floating carrier is a polyurethane foam.
内の廃水の酸化還元電位（Ａｇ／ＡｇＣｌ基準）を＋１
００〜＋２００mVに維持することを特徴とする請求項１
〜３のいづれか１項に記載の方法。4. The oxidation-reduction potential (based on Ag / AgCl) of wastewater in the aerobic tank (2) or the aerobic tank where nitrification is performed is increased by +1.
2. The method according to claim 1, wherein the voltage is maintained at 00 to +200 mV.
The method according to any one of claims 1 to 3.
（Ａｇ／ＡｇＣｌ基準）を−１００〜−２００mVに維持
することを特徴とする請求項１〜４のいづれか１項に記
載の方法。5. The method according to claim 1, wherein the oxidation-reduction potential (based on Ag / AgCl) of the wastewater in the anaerobic tank (3) is maintained at -100 to -200 mV. .
高炉水砕スラグを主原料とするサドル型セラミックスで
あることを特徴とする請求項１〜５のいづれか１項に記
載の方法。6. The packed carrier of the aerobic reactor (5),
The method according to any one of claims 1 to 5, wherein the blast furnace granulated slag is a saddle-shaped ceramic mainly used as a raw material.
化還元電位（Ａｇ／ＡｇＣｌ基準）を、＋１００〜＋２
００mVに維持することを特徴とする請求項１〜６のいづ
れか１項に記載の方法。7. The oxidation-reduction potential (based on Ag / AgCl) of treated water in the aerobic reactor (5) is set to +100 to +2.
7. The method according to claim 1, wherein the voltage is maintained at 00 mV.
The method according to claim 1 .
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33067395A JP3269957B2 (en) | 1995-12-19 | 1995-12-19 | How to remove nitrogen from wastewater |
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|---|---|---|---|
| JP33067395A JP3269957B2 (en) | 1995-12-19 | 1995-12-19 | How to remove nitrogen from wastewater |
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| Publication Number | Publication Date |
|---|---|
| JPH09168796A JPH09168796A (en) | 1997-06-30 |
| JP3269957B2 true JP3269957B2 (en) | 2002-04-02 |
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|---|---|---|---|
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|---|---|---|---|---|
| KR100382890B1 (en) * | 2000-05-16 | 2003-05-09 | 삼안기업 주식회사 | Contact oxidation-type waste water disposal method for integrated septic tank |
| JP4521384B2 (en) * | 2006-09-13 | 2010-08-11 | 有限会社室田工業所 | Nitrogen compound removal equipment |
| JP5097024B2 (en) * | 2008-06-17 | 2012-12-12 | シャープ株式会社 | Water treatment apparatus and water treatment method |
| JP5733785B2 (en) * | 2009-10-20 | 2015-06-10 | メタウォーター株式会社 | Waste water treatment method and waste water treatment equipment |
| CN101759333B (en) * | 2010-02-10 | 2012-05-30 | 彭永臻 | Method for stably maintaining sludge micro-bulking for saving energy in biological denitrification technology |
| JP5984137B2 (en) * | 2012-11-27 | 2016-09-06 | 株式会社日立製作所 | Water treatment apparatus and water treatment method |
| JP5862597B2 (en) * | 2013-04-08 | 2016-02-16 | 栗田工業株式会社 | Biological treatment method and apparatus for organic wastewater |
| JP7181078B2 (en) * | 2018-12-21 | 2022-11-30 | 水ｉｎｇ株式会社 | Water treatment method and water treatment equipment |
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