JP4641116B2

JP4641116B2 - Biological denitrification equipment

Info

Publication number: JP4641116B2
Application number: JP2001101158A
Authority: JP
Inventors: 治夫栗栖
Original assignee: Sumitomo Heavy Industries Environment Co Ltd
Current assignee: Sumitomo Heavy Industries Environment Co Ltd
Priority date: 2001-03-30
Filing date: 2001-03-30
Publication date: 2011-03-02
Anticipated expiration: 2021-03-30
Also published as: JP2002292396A

Description

【０００１】
【発明の属する技術分野】
本発明は、生物脱窒処理装置に係り、より詳細には一つの槽で硝化及び脱窒を行う生物脱窒処理装置に関する。
【０００２】
【従来技術】
排水中の窒素は、湖沼等の閉鎖水域における富栄養化の原因となることから、これを除去することが求められている。排水中の窒素の除去方法として、微生物の作用を利用して生物学的に窒素を除去する生物学的脱窒法、特に循環脱窒法が良く知られている。
【０００３】
循環脱窒法は、一般的に、窒素を含有する被処理水を脱窒槽及び硝化槽に順次導入し、硝化槽で得られる処理水の一部を脱窒槽に返送することにより被処理水の脱窒処理を行うものである。このような循環脱窒法においては、被処理水の流入量をＱ、硝化槽から脱窒槽への返送量をｎＱ、硝化槽の後段に設けた沈殿槽から脱窒槽への返送量をｒＱとすると、理論窒素除去率ｘは、一般に下記式：
【０００４】
【数１】

で表される。従って、硝化槽から脱窒槽への処理水の返送量を大きくすればするほど、窒素除去率が大きくなる。ところが、循環脱窒法では、脱窒槽と硝化槽とが別体となっているため、設置面積が大きくなってしまうという問題がある。
【０００５】
そこで、例えば特開平７−６８２９３号公報に開示されるように、脱窒と硝化とを一つの反応槽で行う生物脱窒処理装置の発明がなされている。同公報に記載の生物脱窒処理装置１００は、図２に示すように、一つの反応槽１０１を有し、反応槽１０１の下部は脱窒部１０２となっており、脱窒部１０２の底部には配管１０３を経て原水が流入され、上部には配管１０４を経て空気が導入される。脱窒部１０２の上方には、硝化細菌を付着させた担体が充填された生物濾過層からなる硝化部１０５がある。硝化部１０５で得られる処理水は、排出配管１０６を経て処理水槽１０７に導入され、処理水槽１０７から配管１０８，１０９を経て系外へ排出され、処理水の一部は、配管１１０を経て配管１０３に導入される。このような生物脱窒処理装置１００は、一つの反応槽１０１で硝化と脱窒を行うため設置面積を小さくすることができる。
【０００６】
【発明が解決しようとする課題】
しかしながら、生物脱窒処理装置１００は、以下に示す課題を有している。
【０００７】
即ち生物脱窒処理装置１００は、硝化部１０５で得られた処理水を配管１０６を経て処理水槽１０７に貯留し、貯留された処理水を配管１０８，１１０を経て配管１０３に流入させている。この場合、硝化部１０６の水面と処理水槽１０７内に貯留された処理水の水面は同じ（もしくは下方の）位置にあり、水位差がないため、配管１０３に処理水を十分に流入させることができず、窒素除去率を十分に高めることができない。ここで、窒素除去率を十分に高くするために、配管１０８又は配管１１０に大容量のポンプを設置することも考えられるが、これでは、設備が大型化するだけでなく、多大な動力が必要となり、ランニングコストが嵩むことになる。
【０００８】
本発明は、上記事情に鑑みてなされたものであり、窒素除去率を十分に高くし且つ設備の小型化、ランニングコストの低減を可能とする生物脱窒処理装置を提供することを目的とする。
【０００９】
【課題を解決するための手段】
上記課題を解決するため、本発明は、一つの反応槽に脱窒部と硝化部とを有し、被処理水を前記脱窒部及び前記硝化部で順次処理して処理水を得てその少なくとも一部を脱窒部に返送する生物脱窒処理装置において、反応槽の内部を上部の脱窒部と下部の硝化部とに仕切る仕切部材と、硝化部にガスを導入するガス導入手段と、ガス導入手段により導入されるガス及び硝化部の処理水を含む気液混合水を脱窒部の水面より高い位置まで導く第１配管と、第１配管に設けられ、第１配管により導かれる気液混合水から硝化部の処理水を分離する分離槽と、分離槽で得られた処理水の少なくとも一部を脱窒部に返送する第２配管とを備えることを特徴とする。
【００１０】
この発明によれば、ガス導入手段により硝化部にガスを導入すると、ガスリフト効果によりガス及び硝化部の処理水を含む気液混合水が第１配管を経て上昇させられ、硝化部で得られた処理水は、脱窒部の水面より高い位置まで導かれる。そして、分離槽で気液混合水から硝化部の処理水が分離され、分離された処理水の少なくとも一部は第２配管を経て脱窒部へと返送される。このとき、分離槽で得られた処理水は、脱窒部の水面より高い位置まで導かれるので、この水位差により、分離槽で分離された処理水は、大容量のポンプを用いることなく脱窒部へ十分に返送されることとなる。
【００１１】
上記発明において、前記仕切部材と前記硝化部の水面との間に溜められるガスを前記硝化部から排出するガス排出手段を更に備えることが好ましい。
【００１２】
仕切部材と硝化部の水面との間に多量のガスが溜められた場合、ガスリフト効果により、第１配管を上昇しやすくなるが、この場合、分離槽から第２配管を経て脱窒部へ返送される処理水の流量が多くなり、被処理水が安定して処理されなくなる場合がある。そこで、仕切部材と硝化部の水面との間に多量のガスが溜められた場合、ガス排出手段により硝化部からガスが排出され、脱窒部へ返送される処理水の流量が安定化され、被処理水が安定して処理されることとなる。
【００１３】
上記発明において、硝化部の溶存酸素濃度に基づいて、前記ガス排出手段のガス排出量及び前記ガス導入手段のガス導入量を制御する制御手段を更に備えることが好ましい。
【００１４】
例えば残存溶存酸素濃度が小さくなった場合、これは酸素消費量が多くなっていることを意味する。この場合、制御手段により、ガス導入手段を制御して硝化部に導入されるガスの量を多くする。また、ガスの量を多くすると、仕切部材と硝化部の水面との間に多量の空気が溜められるので、制御手段によりガス排出手段を制御してこのガスを排出する。このようにすることによって、硝化部での処理効率を調節できると共に、硝化部で得られた処理水の脱窒部への返送量を調節することもでき、被処理水を安定して処理することができる。
【００１５】
【発明の実施の形態】
以下、本発明の実施形態について詳細に説明する。
【００１６】
図１は、本発明の生物脱窒処理装置の一実施形態を示す断面図である。図１に示すように、生物脱窒処理装置１は、一つの反応槽２を備えており、反応槽２の内部には、反応槽２の内部を脱窒部３と硝化部４とに仕切る仕切部材５が設けられている。この仕切部材５により反応槽２の上部には脱窒部３が形成され、下部には硝化部４が形成されている。脱窒部３には、原水（被処理水）を脱窒部３に導入する原水導入管６が接続されている。また、脱窒部３と硝化部４とは、脱窒部３で処理された脱窒処理水を硝化部４に移送する脱窒処理水移送管７によって接続されている。
【００１７】
一方、硝化部４には散気管８が配設され、散気管８には空気導入管９を経てブロワ１０が接続されている。そして、ブロワ１０を作動することにより空気導入管９及び散気管８を経て硝化部４に空気が導入される。散気管８、空気導入管９及びブロワ１０によりガス導入手段が構成されている。
【００１８】
反応槽２のほぼ中央には、硝化部４から上方に向かってストレートに延びる上昇配管（第１配管）１１が設けられ、上昇配管１１は脱窒部３及び反応槽２の天井部を貫通し、反応槽２の外部まで延びている。上昇配管１１の先端には気液分離槽１２が設けられている。
【００１９】
気液分離槽１２には処理水排出管１３が接続され、処理水排出管１３からは、返送配管（第２配管）１４が分岐して脱窒部３に接続されている。なお、処理水は、処理水排出管１３を経て沈殿槽に導入される。
【００２０】
次に、前述した生物脱窒処理装置１を用いた生物脱窒処理方法について説明する。
【００２１】
まず原水導入配管６を経て原水を脱窒部３に導入する。脱窒部３では、硝酸塩が窒素ガスに還元される。脱窒部３で処理された脱窒処理水は、脱窒処理水移送管７を経て硝化部４に導入される。このとき、ブロワ１０を作動し、空気導入管９及び散気管８を経て硝化部４に空気を導入する。すると、硝化部４では、導入された空気によって、水中に含まれるアンモニア態窒素が硝酸、亜硝酸に酸化される。一方、硝化部４に導入された空気は上昇し、上昇配管１１に入りこむ。すると、ガスリフト効果により空気及び硝化部４で得られた処理水を含む気液混合水が上昇配管１１を経て上昇させられ、気液混合水は脱窒部３の水面より高い位置まで導かれる。この気液混合水は気液分離槽１２まで導かれ、気液分離槽１２において気液混合水から処理水が分離され、処理水の一部は処理水排出管１３及び返送配管１４を経て脱窒部３へと返送される。このとき、気液分離槽１２において、硝化部４で得られる処理水は脱窒部３の水面より高い位置まで導かれている。このため、この水位差より、気液分離槽１２で得られた処理水は、大容量のポンプを用いることなく脱窒部３へ十分に返送されることとなる。よって、脱窒部３で窒素除去率を十分に向上させることができる。また、大容量のポンプを用いることなく処理水が脱窒部３へ返送されるため、設備の小型化、ランニングコストの低減を図ることが可能となる。
【００２２】
上記実施形態において、硝化部４に空気を導入すると、空気が硝化部４の水面と仕切部材５との間に溜められることとなる。そして、この空気の量が多くなると、ガスリフト効果により、上昇配管１１を上昇しやすくなる。しかし、この場合、気液分離槽１２から返送配管を経て脱窒部３へ返送される処理水の流量が多くなり、被処理水が安定して処理されなくなる場合もある。そこで、仕切部材５と硝化部４の水面との間に多量のガスが溜められた場合には、硝化部４からガスを排出し、脱窒部３へ返送される処理水の流量を安定化し、被処理水を安定して処理することが好ましい。このため、仕切部材５には排出配管１５が設けられ、ガス排出配管１５にはバルブ１６が設けられている。バルブ１６の開閉により硝化部４の水面と仕切部材５との間に溜められる空気の排出量が調節され、硝化部４の処理水の脱窒部３への返送量が調節されることとなる。なお、ガス排出配管１５とバルブ１６によりガス排出手段が構成されている。
【００２３】
ここで、仕切部材５は図１に示すように円錐形状となっていることが好ましい。この場合、空気が仕切部材５の上部の一箇所に集中して捕集されることとなるので、空気の排出量の調節幅を大きくすることができる。なお、仕切部材５の形状は、空気を一箇所に集中して捕集できるものであればよく、従って、円錐形状に限らず、四角錐形状であってもよい。
【００２４】
また、生物脱窒処理装置１は、硝化部４の溶存酸素濃度を測定する溶存酸素濃度計（図示せず）と、この溶存酸素濃度計で測定された溶存酸素濃度に基づいて、ガス排出配管１５に取り付けたバルブ１６及びブロワ１０を制御する制御装置（制御手段）とを更に備えることが好ましい。
【００２５】
例えば残存溶存酸素濃度が小さくなった場合、酸素消費量が多くなっていることを意味する。この場合、制御装置により、ブロワ１０の出力を調節して硝化部４に導入される空気の量を多くして硝化部４に空気を補給する。また、空気の量を多くすると、仕切部材５と硝化部４の水面との間に多量の空気が溜められるので、制御装置によりバルブ１６を開いてこの空気を排出するのである。このようにすることによって、硝化部４での処理効率を調節できると共に、硝化部４で得られた処理水の脱窒部３への返送量を調節することもでき、原水を安定して処理することができる。
【００２６】
本発明は、前述した実施形態に限定されるものではない。例えば上記実施形態では、処理水の一部が沈殿槽に導入されるようになっているが、硝化部４に膜分離装置を配設した場合には、沈殿槽は不要である。この場合、気液分離槽１２から処理水を沈殿槽に導入するための配管は不要である。
【００２７】
また、気液分離槽１２は、反応槽２の外部に設けられているが、気液分離槽１２は、気液分離槽１２における硝化部４からの処理水の水面を脱窒部３の水面より高い位置にすることができれば如何なる位置に設けられても良い。従って、気液分離槽１２は例えば脱窒部３の内部に設けられても良い。
【００２８】
【発明の効果】
以上説明したように本発明の生物脱窒処理装置によれば、硝化部で得られる処理水が脱窒部の水面より高い位置まで導かれるため、分離槽で得られた処理水を、大容量のポンプを要することなく、十分に脱窒部へと返送することが可能となる。従って、脱窒部で窒素除去率を十分に向上させることができる。また、大容量のポンプが不要となるため、設備の小型化、ランニングコストの低減が可能となる。
【図面の簡単な説明】
【図１】本発明の生物脱窒処理装置の一実施形態を示す断面図である。
【図２】従来の生物脱窒処理装置の一例を示す断面図である。
【符号の説明】
１…生物脱窒処理装置、２…反応槽、３…脱窒部、４…硝化部、５…仕切部材、８…散気管（ガス導入手段）、９…空気導入管（ガス導入手段）、１０…ブロワ（ガス導入手段）、１１…上昇配管（第１配管）、１２…気液分離槽（分離槽）、１４…返送配管（２配管）、１５…空気排出管（ガス排出手段）、１６…バルブ（ガス排出手段）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a biological denitrification processing apparatus, and more particularly to a biological denitrification processing apparatus that performs nitrification and denitrification in one tank.
[0002]
[Prior art]
Nitrogen in wastewater causes eutrophication in closed water areas such as lakes and marshes, so it is required to remove it. As a method for removing nitrogen in wastewater, a biological denitrification method that removes nitrogen biologically by utilizing the action of microorganisms, particularly a circulating denitrification method is well known.
[0003]
In general, the circulating denitrification method introduces water to be treated containing nitrogen sequentially into a denitrification tank and a nitrification tank, and returns part of the treated water obtained in the nitrification tank to the denitrification tank to remove the treated water. Nitrogen treatment is performed. In such a circulation denitrification method, when the inflow amount of water to be treated is Q, the return amount from the nitrification tank to the denitrification tank is nQ, and the return amount from the settling tank provided at the latter stage of the nitrification tank to the denitrification tank is rQ. The theoretical nitrogen removal rate x generally has the following formula:
[0004]
[Expression 1]

It is represented by Therefore, the greater the amount of treated water returned from the nitrification tank to the denitrification tank, the greater the nitrogen removal rate. However, in the circulation denitrification method, the denitrification tank and the nitrification tank are separated from each other, so that there is a problem that the installation area becomes large.
[0005]
Therefore, for example, as disclosed in JP-A-7-68293, an invention of a biological denitrification treatment apparatus that performs denitrification and nitrification in one reaction tank has been made. As shown in FIG. 2, the biological denitrification apparatus 100 described in the publication has one reaction tank 101, and the lower part of the reaction tank 101 is a denitrification part 102, and the bottom of the denitrification part 102 The raw water is introduced into the pipe through the pipe 103 and air is introduced into the upper part through the pipe 104. Above the denitrification unit 102 is a nitrification unit 105 composed of a biofiltration layer filled with a carrier to which nitrifying bacteria are attached. The treated water obtained in the nitrification unit 105 is introduced into the treated water tank 107 through the discharge pipe 106, discharged from the treated water tank 107 through the

pipes

108 and 109, and part of the treated water is piped through the pipe 110. 103. Since such a biological denitrification apparatus 100 performs nitrification and denitrification in one reaction tank 101, the installation area can be reduced.
[0006]
[Problems to be solved by the invention]
However, the biological denitrification apparatus 100 has the following problems.
[0007]
That is, the biological denitrification processing apparatus 100 stores the treated water obtained in the nitrification unit 105 in the treated water tank 107 through the pipe 106 and flows the stored treated water into the pipe 103 through the

pipes

108 and 110. In this case, since the water surface of the nitrification unit 106 and the water surface of the treated water stored in the treated water tank 107 are at the same (or lower) position and there is no difference in water level, the treated water can sufficiently flow into the pipe 103. It is not possible to sufficiently increase the nitrogen removal rate. Here, in order to sufficiently increase the nitrogen removal rate, it is conceivable to install a large-capacity pump in the pipe 108 or the pipe 110, but this not only increases the size of the equipment but also requires a large amount of power. As a result, running costs increase.
[0008]
This invention is made | formed in view of the said situation, and it aims at providing the biological denitrification processing apparatus which makes a nitrogen removal rate high enough, and enables size reduction of an installation and reduction of a running cost. .
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has a denitrification unit and a nitrification unit in one reaction tank, and sequentially treats the treated water in the denitrification unit and the nitrification unit to obtain treated water. In a biological denitrification processing apparatus that returns at least a part to the denitrification unit, a partition member that partitions the inside of the reaction tank into an upper denitrification unit and a lower nitrification unit, and gas introduction means for introducing gas into the nitrification unit; The first pipe for guiding the gas-liquid mixed water including the gas introduced by the gas introduction means and the treated water of the nitrification part to a position higher than the water surface of the denitrification part, and the first pipe are provided and led by the first pipe A separation tank that separates the treated water of the nitrification unit from the gas-liquid mixed water, and a second pipe that returns at least a part of the treated water obtained in the separation tank to the denitrification unit.
[0010]
According to this invention, when gas is introduced into the nitrification unit by the gas introduction means, the gas-liquid mixed water containing the gas and the treated water of the nitrification unit is raised through the first pipe due to the gas lift effect, and obtained in the nitrification unit The treated water is guided to a position higher than the water surface of the denitrification unit. Then, the treated water in the nitrification unit is separated from the gas-liquid mixed water in the separation tank, and at least a part of the separated treated water is returned to the denitrification unit via the second pipe. At this time, the treated water obtained in the separation tank is guided to a position higher than the water surface of the denitrification unit, so that the treated water separated in the separation tank is removed without using a large-capacity pump due to this water level difference. It will be fully returned to Nikko.
[0011]
The said invention WHEREIN: It is preferable to further provide the gas discharge means which discharges | emits the gas stored between the said partition member and the water surface of the said nitrification part from the said nitrification part.
[0012]
When a large amount of gas is accumulated between the partition member and the water surface of the nitrification unit, the first pipe is likely to rise due to the gas lift effect. In this case, the gas is returned from the separation tank to the denitrification unit via the second pipe. The flow rate of the treated water increases, and the treated water may not be treated stably. Therefore, when a large amount of gas is accumulated between the partition member and the water surface of the nitrification unit, the gas is discharged from the nitrification unit by the gas discharge means, and the flow rate of the treated water returned to the denitrification unit is stabilized, The treated water will be treated stably.
[0013]
In the above invention, it is preferable to further comprise a control means for controlling the gas discharge amount of the gas discharge means and the gas introduction amount of the gas introduction means based on the dissolved oxygen concentration in the nitrification part.
[0014]
For example, if the residual dissolved oxygen concentration is reduced, this means that the oxygen consumption is increased. In this case, the control means controls the gas introduction means to increase the amount of gas introduced into the nitrification unit. Further, when the amount of gas is increased, a large amount of air is stored between the partition member and the water surface of the nitrification unit, so that the control unit controls the gas discharge unit to discharge this gas. By doing in this way, while being able to adjust the processing efficiency in a nitrification part, the return amount to the denitrification part of the treated water obtained in the nitrification part can also be adjusted, and treated water is treated stably. be able to.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0016]
FIG. 1 is a cross-sectional view showing an embodiment of the biological denitrification apparatus of the present invention. As shown in FIG. 1, the biological denitrification apparatus 1 includes a single reaction tank 2, and the reaction tank 2 is divided into a denitrification unit 3 and a nitrification unit 4 inside the reaction tank 2. A partition member 5 is provided. The partition member 5 forms a denitrification unit 3 at the top of the reaction tank 2 and a nitrification unit 4 at the bottom. A raw water introduction pipe 6 for introducing raw water (treated water) into the denitrification unit 3 is connected to the denitrification unit 3. Further, the denitrification unit 3 and the nitrification unit 4 are connected by a denitrification water transfer pipe 7 that transfers the denitrification water treated by the denitrification unit 3 to the nitrification unit 4.
[0017]
On the other hand, a diffusing pipe 8 is disposed in the nitrification unit 4, and a blower 10 is connected to the diffusing pipe 8 through an air introduction pipe 9. Then, by operating the blower 10, air is introduced into the nitrification unit 4 through the air introduction pipe 9 and the air diffusion pipe 8. The gas introduction means is constituted by the air diffusion pipe 8, the air introduction pipe 9, and the blower 10.
[0018]
A rising pipe (first pipe) 11 that extends straight upward from the nitrification unit 4 is provided at substantially the center of the reaction tank 2, and the rising pipe 11 passes through the denitrification unit 3 and the ceiling of the reaction tank 2. , Extending to the outside of the reaction vessel 2. A gas-liquid separation tank 12 is provided at the tip of the ascending pipe 11.
[0019]
A treated water discharge pipe 13 is connected to the gas-liquid separation tank 12, and a return pipe (second pipe) 14 is branched from the treated water discharge pipe 13 and connected to the denitrification unit 3. The treated water is introduced into the settling tank through the treated water discharge pipe 13.
[0020]
Next, a biological denitrification processing method using the biological denitrification processing apparatus 1 described above will be described.
[0021]
First, raw water is introduced into the denitrification section 3 through the raw water introduction pipe 6. In the denitrification unit 3, nitrate is reduced to nitrogen gas. The denitrification water treated in the denitrification unit 3 is introduced into the nitrification unit 4 through the denitrification water transfer pipe 7. At this time, the blower 10 is operated to introduce air into the nitrification unit 4 through the air introduction pipe 9 and the air diffusion pipe 8. Then, in the nitrification unit 4, ammonia nitrogen contained in the water is oxidized into nitric acid and nitrous acid by the introduced air. On the other hand, the air introduced into the nitrification unit 4 rises and enters the ascending pipe 11. Then, the gas-liquid mixed water containing the treated water obtained in the air and the nitrification unit 4 is raised through the ascending pipe 11 due to the gas lift effect, and the gas-liquid mixed water is guided to a position higher than the water surface of the denitrification unit 3. This gas-liquid mixed water is guided to the gas-liquid separation tank 12, and the treated water is separated from the gas-liquid mixed water in the gas-liquid separation tank 12, and a part of the treated water is removed via the treated water discharge pipe 13 and the return pipe 14. Returned to Nikko 3 At this time, in the gas-liquid separation tank 12, the treated water obtained in the nitrification unit 4 is guided to a position higher than the water surface of the denitrification unit 3. For this reason, the treated water obtained in the gas-liquid separation tank 12 is sufficiently returned to the denitrification unit 3 without using a large-capacity pump due to this water level difference. Therefore, the nitrogen removal rate can be sufficiently improved by the denitrification unit 3. In addition, since the treated water is returned to the denitrification unit 3 without using a large-capacity pump, it is possible to reduce the size of the equipment and reduce the running cost.
[0022]
In the above embodiment, when air is introduced into the nitrification unit 4, the air is accumulated between the water surface of the nitrification unit 4 and the partition member 5. And when this amount of air increases, it becomes easy to ascend the ascending pipe 11 due to the gas lift effect. However, in this case, the flow rate of the treated water returned from the gas-liquid separation tank 12 to the denitrification unit 3 through the return pipe may increase, and the treated water may not be stably treated. Therefore, when a large amount of gas is accumulated between the partition member 5 and the water surface of the nitrification unit 4, the gas is discharged from the nitrification unit 4 and the flow rate of the treated water returned to the denitrification unit 3 is stabilized. The treated water is preferably treated stably. Therefore, the partition member 5 is provided with a discharge pipe 15, and the gas discharge pipe 15 is provided with a valve 16. By opening and closing the valve 16, the discharge amount of air stored between the water surface of the nitrification unit 4 and the partition member 5 is adjusted, and the return amount of the treated water of the nitrification unit 4 to the denitrification unit 3 is adjusted. . The gas discharge pipe 15 and the valve 16 constitute a gas discharge means.
[0023]
Here, it is preferable that the partition member 5 has a conical shape as shown in FIG. In this case, since air is concentrated and collected at one place on the upper part of the partition member 5, the adjustment range of the air discharge amount can be increased. In addition, the shape of the partition member 5 should just be what can concentrate and collect air on one place, Therefore Not only a cone shape but square pyramid shape may be sufficient.
[0024]
In addition, the biological denitrification apparatus 1 includes a dissolved oxygen concentration meter (not shown) that measures the dissolved oxygen concentration in the nitrification unit 4 and a gas discharge pipe based on the dissolved oxygen concentration measured by the dissolved oxygen concentration meter. It is preferable to further include a control device (control means) for controlling the valve 16 and the blower 10 attached to 15.
[0025]
For example, when the residual dissolved oxygen concentration is reduced, it means that the oxygen consumption is increased. In this case, the control device adjusts the output of the blower 10 to increase the amount of air introduced into the nitrification unit 4 and replenish the nitrification unit 4 with air. Further, when the amount of air is increased, a large amount of air is accumulated between the partition member 5 and the water surface of the nitrification unit 4, so that the control device opens the valve 16 and discharges this air. By doing in this way, while being able to adjust the processing efficiency in the nitrification part 4, the amount of return of the treated water obtained in the nitrification part 4 to the denitrification part 3 can also be adjusted, and raw water can be treated stably. can do.
[0026]
The present invention is not limited to the embodiment described above. For example, in the above embodiment, a part of the treated water is introduced into the precipitation tank, but when a membrane separation device is disposed in the nitrification unit 4, the precipitation tank is not necessary. In this case, piping for introducing treated water from the gas-liquid separation tank 12 to the precipitation tank is not necessary.
[0027]
The gas-liquid separation tank 12 is provided outside the reaction tank 2, and the gas-liquid separation tank 12 uses the water level of the treated water from the nitrification unit 4 in the gas-liquid separation tank 12 as the water level of the denitrification unit 3. Any position may be used as long as the position can be higher. Therefore, the gas-liquid separation tank 12 may be provided inside the denitrification unit 3, for example.
[0028]
【The invention's effect】
As described above, according to the biological denitrification treatment apparatus of the present invention, the treated water obtained in the nitrification unit is guided to a position higher than the water surface of the denitrification unit. Therefore, it is possible to sufficiently return to the denitrification section without requiring a pump. Therefore, the nitrogen removal rate can be sufficiently improved in the denitrification section. In addition, since a large-capacity pump is not required, the equipment can be downsized and the running cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a biological denitrification apparatus of the present invention.
FIG. 2 is a cross-sectional view showing an example of a conventional biological denitrification apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Biological denitrification processing apparatus, 2 ... Reaction tank, 3 ... Denitrification part, 4 ... Nitrification part, 5 ... Partition member, 8 ... Air diffusion pipe (gas introduction means), 9 ... Air introduction pipe (gas introduction means), DESCRIPTION OF SYMBOLS 10 ... Blower (gas introduction means), 11 ... Ascending piping (1st piping), 12 ... Gas-liquid separation tank (separation tank), 14 ... Return piping (2 piping), 15 ... Air exhaust pipe (gas discharge means), 16 ... Valve (gas discharge means).

Claims

One reaction tank has a denitrification unit and a nitrification unit, and sequentially treats the water to be treated in the denitrification unit and the nitrification unit to obtain treated water, and returns at least a part thereof to the denitrification unit. In biological denitrification equipment,
A partition member for partitioning the inside of the reaction tank, forming the denitrification unit at the top, and forming the nitrification unit at the bottom;
Gas introduction means for introducing gas into the nitrification unit;
A first pipe for guiding the gas-liquid mixed water containing the gas introduced by the gas introduction means and the treated water of the nitrification unit to a position higher than the water surface of the denitrification unit;
A separation tank that is provided in the first pipe and separates the treated water of the nitrification unit from the gas-liquid mixed water guided by the first pipe;
A second pipe that returns at least a portion of the treated water obtained in the separation tank to the denitrification unit;
A biological denitrification treatment apparatus comprising:

The biological denitrification apparatus according to claim 1, further comprising a gas discharge unit that discharges a gas accumulated between the partition member and a water surface of the nitrification unit from the nitrification unit.

The biological denitrification according to claim 2, further comprising a control unit that controls a gas discharge amount of the gas discharge unit and a gas introduction amount of the gas introduction unit based on a dissolved oxygen concentration in the nitrification unit. Processing equipment.