JPS5864198A - Method and apparatus for biologically denitrifying waste water - Google Patents

Abstract

PURPOSE:To suppress the aerobic consumption of organic substance in a denitrifying cell, by nitrifying and denitrifying waste water containing nitrogen compounds and organic compounds, and separating the treated water into solid matter and liquid by a pressurized floating method using gas formed by the denitrification. CONSTITUTION:Raw water from a waste water-inflow pipe 1, nitric nitrogen- contg. nitrified mixed liquid from a nitrified mixed liquid-introducing pipe 4 and separated sludge over a partition wall 14 are introduced into a denitrifying cell 2. The waste water denitrified in the denitrifying cell 2 is introduced into a nitrifying cell 3, nitrified therein and then introduced into a floating cell 8. A part of purified water and nitrogen-contg. gas from a gas-introducing pipe 15 are introduced into a pressurized tank 9, and the gas is dissolved in the water to be purified under pressure to prepare pressurized water. Said pressurized water together with a part of the nitrified mixed liquid is introduced into the floating cell 8 through its lower part to separate sludge by flotation. The sludge concentrated by flotation is partially introduced into the denitrifying cell 2 by a scraping-out means 10, while excess sludge is withdrawn.

Description

Translated fromJapanese

【発明の詳細な説明】本発明は下水、ＬｂＷなど有機物及び窒素化合物を含有
する廃水を生物学的に処理する方法及び装置に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for biologically treating sewage and wastewater containing organic matter and nitrogen compounds such as LbW.

現在、各種廃水から窒素を除去する方法と・しては、生
物学的方法が最も多く用いられている。この方法を実施
する装置は、脱窒槽、硝化槽及び固液分離槽から構成さ
れ、原水を脱窒槽に流入させ、硝化槽内の混合液及び固
液分離槽の汚泥を脱窒槽に返送して脱窒処理を行ない、
次に硝化槽に導入して硝化処理を行ない、硝化混合液を
固液分離槽で固液分離する。固液分離は従来、一般に重
力沈降によりなされているが、汚泥の沈降速妾が遅いた
め、長い滞留時間を必要とし、濃縮汚泥濃度もれている
が、加圧浮上により酸素含有気泡の付着した濃縮汚泥が
脱窒槽へ返送され、脱窒槽の嫌気条件が悪化してし甘う
。脱窒工程は、脱窒菌の作用により硝酸性窒素（Ｎ０３
−）から０２を奪ってＮ２を発生すると共に、有機物を
分解する工程である。Currently, biological methods are most often used to remove nitrogen from various wastewaters. The equipment that implements this method consists of a denitrification tank, a nitrification tank, and a solid-liquid separation tank. Raw water flows into the denitrification tank, and mixed liquid in the nitrification tank and sludge in the solid-liquid separation tank are returned to the denitrification tank. Perform denitrification treatment,
Next, it is introduced into a nitrification tank for nitrification treatment, and the nitrified mixture is separated into solid and liquid in a solid-liquid separation tank. Conventionally, solid-liquid separation has generally been carried out by gravity settling, but since the settling speed of sludge is slow, it requires a long residence time and the concentration of concentrated sludge leaks. Thickened sludge is returned to the denitrification tank, worsening the anaerobic conditions in the denitrification tank. In the denitrification process, nitrate nitrogen (N03
This is a process that takes away 02 from (-) to generate N2 and decomposes organic matter.

従って、ＮＯ３−以外にフリーな０２−が存在すると、
ＮＯ３−は分解せずにフリーな０２が有機物を消費して
しまい、脱窒に必要な有機物が不足し、脱窒率が低下す
る。このため、脱窒槽は嫌気性状態に維持される必要が
あり、逆に硝化槽ではＮＨ３性Ｎを硝酸性Ｎに変えるた
めに好気性状態に維持される必要がある。Therefore, if free 02- exists in addition to NO3-,
NO3- is not decomposed and free 02 consumes organic matter, resulting in a shortage of organic matter necessary for denitrification, and the denitrification rate decreases. For this reason, the denitrification tank needs to be maintained in an anaerobic state, and conversely, the nitrification tank needs to be maintained in an aerobic state in order to convert NH3 N into nitrate N.

本発明の目的は、前記従来技術の欠点を解消し、濃縮汚
泥濃度を高め、同時に脱窒槽及び硝化槽内の汚泥濃度を
高くすることができ、脱窒槽での有機物の好気的消費を
極力抑制しうる生物学的膜窒素方法及び装置を提喉する
ことにある。The purpose of the present invention is to eliminate the drawbacks of the prior art, increase the concentration of concentrated sludge, and at the same time increase the concentration of sludge in the denitrification tank and nitrification tank, and to minimize the aerobic consumption of organic matter in the denitrification tank. The purpose of the present invention is to provide a method and apparatus for suppressing biological membrane nitrogen.

この目的は本発明によれば、脱窒素により発生した窒素
ガスを含む気体を加圧し、処理水に溶解させ、汚泥の浮
上濃縮に用いることによって達成される。即ち、本発明
方法は脱窒工程で生じた気体を用いて加圧浮上により固
液分離を行なうことを特徴とする。This object is achieved according to the invention by pressurizing a gas containing nitrogen gas generated by denitrification, dissolving it in the treated water, and using it for flotation concentration of sludge. That is, the method of the present invention is characterized in that solid-liquid separation is performed by pressurized flotation using the gas generated in the denitrification step.

本発明方法を効果的に実施するには、脱窒槽と固液分離
槽を同一密閉室内に隣設させ、脱窒槽で生成する気体を
パイプにより加圧タンクに導ひき、加圧浮上に利用する
のが有利である。In order to effectively carry out the method of the present invention, the denitrification tank and the solid-liquid separation tank are placed next to each other in the same sealed room, and the gas generated in the denitrification tank is led to the pressurized tank through a pipe and used for pressurized flotation. is advantageous.

次に、本発明の脱窒素方法及び装置を従来例（第１図、
第２図）と対比して第３図に基づいて説明する。従来の
脱窒素処理では、第１図に示すように、原水を廃水流入
管ｌから脱窒槽２に導入し、硝化槽３で硝化を行なった
硝化混合液の一部を】４管４により脱窒槽２へ循環させ
、返送汚泥管５から汚泥を返送し、脱窒処理を行なう。Next, a conventional example (Fig. 1,
This will be explained based on FIG. 3 in comparison with FIG. 2). In conventional denitrification treatment, as shown in Fig. 1, raw water is introduced into a denitrification tank 2 through a wastewater inflow pipe 1, and a portion of the nitrified mixture that has been nitrified in a nitrification tank 3 is denitrified through a pipe 4. The sludge is circulated to the nitrogen tank 2 and returned from the return sludge pipe 5 for denitrification treatment.

硝化槽３で硝化された硝化混合液の残部は沈殿槽６に導
入して汚泥の沈降分離を行ない、処理水を放流管７から
排出し、余剰汚泥を排泥管１３から排出させる。硝化槽
３内はブロア１１から供給される空＆により好気性状態
に維持されている。The remainder of the nitrified mixed liquid nitrified in the nitrification tank 3 is introduced into a settling tank 6 to perform sedimentation and separation of sludge, the treated water is discharged from the discharge pipe 7, and the excess sludge is discharged from the sludge pipe 13. The inside of the nitrification tank 3 is maintained in an aerobic state by air supplied from a blower 11.

前記の沈殿槽６の代わりに、浮上分離槽８を設けた装置
を第２図に示す。加圧タンク９では処理水に空気導入管
１２より導入された空気を加圧溶解させ、この加圧水を
浮上分離槽８へ導入する。FIG. 2 shows an apparatus in which a flotation tank 8 is provided in place of the sedimentation tank 6 described above. In the pressurized tank 9, the air introduced through the air introduction pipe 12 is dissolved in the treated water under pressure, and this pressurized water is introduced into the flotation separation tank 8.

浮上分離槽８で放圧により生じた気泡は汚泥に付着し、
汚泥を水面へ浮上させる。浮上分離槽８の上には汚泥掻
出装置１０が設けられていて、汚泥を掻出し、汚泥の一
部は脱窒槽２へ返送され、残部は排泥管１３より排出さ
れる。Air bubbles generated by pressure release in the flotation tank 8 adhere to the sludge,
Bring the sludge to the surface of the water. A sludge scraping device 10 is provided above the flotation separation tank 8 to scrape out the sludge, part of the sludge is returned to the denitrification tank 2, and the remaining part is discharged from the sludge pipe 13.

このような構成では、脱窒槽２へ返送する汚泥には酸素
含有気泡（空気）が付着しており、脱窒槽に有機物を消
費するフリーの０２　　が供給されてし捷う。In such a configuration, oxygen-containing bubbles (air) are attached to the sludge returned to the denitrification tank 2, and free O2, which consumes organic matter, is supplied to the denitrification tank and shredded.

第３図は本発明の装置の一実施例を示すフローシートで
ある。この装置では、１個の密閉室が隔壁１４により脱
窒槽２と浮上分離槽８に区分されている。脱窒槽２には
、廃水流入管１から原水、硝化混合液導入管４から硝酸
性窒素を含む硝化混合液及び隔壁１４の上から分離汚泥
が導入される。FIG. 3 is a flow sheet showing one embodiment of the apparatus of the present invention. In this device, one sealed chamber is divided into a denitrification tank 2 and a flotation separation tank 8 by a partition wall 14. Into the denitrification tank 2, raw water is introduced from the wastewater inflow pipe 1, nitrification mixed liquid containing nitrate nitrogen is introduced from the nitrification mixed liquid introduction pipe 4, and separated sludge is introduced from above the partition wall 14.

る。一方、加圧タンク９には処理水の一部及び気体導出
管１５から脱窒槽及び浮上分離槽の上部の窒素ガスを含
む気体が導入され、ここで処理水に気体を加圧溶解させ
、加圧水とする。この加圧水及び硝化混合液の一部を浮
上分離槽８の下部から導入し、汚泥を浮上分離する。浮
上濃縮された汚泥は、一部は掻出装置ｌＯにより脱窒槽
２へ導入され、余剰汚泥は排泥管１３から引抜かれる。Ru. On the other hand, a part of the treated water and a gas containing nitrogen gas from the upper part of the denitrification tank and flotation tank are introduced from the gas outlet pipe 15 into the pressurized tank 9, where the gas is dissolved in the treated water under pressure, and the pressurized water shall be. A portion of this pressurized water and nitrification mixture is introduced from the lower part of the flotation tank 8, and the sludge is floated and separated. Part of the floated and concentrated sludge is introduced into the denitrification tank 2 by the scraping device IO, and excess sludge is pulled out from the sludge pipe 13.

他方、浮上分離槽８の下層液は処理水として放流管７か
ら導出される。On the other hand, the lower layer liquid in the flotation separation tank 8 is led out from the discharge pipe 7 as treated water.

第３図に示した構成によれば、加圧浮上に脱窒槽内で生
成した気体を利用し、酸素含有気体を使用していないの
で、脱窒槽に有機物を消費するフリーな０２　　が返送
汚泥により搬入されず、脱窒槽内を良好な嫌気性状態に
保持しながら汚泥濃度を高くすることができる。According to the configuration shown in Figure 3, the gas generated in the denitrification tank is used for pressurized flotation, and oxygen-containing gas is not used. The sludge concentration can be increased while maintaining the inside of the denitrification tank in a good anaerobic state.

次に、実施例に基づいて本発明を詳述するが、本発明は
これに限定されるものではない。Next, the present invention will be described in detail based on Examples, but the present invention is not limited thereto.

及び６量５０１の硝化槽を有する第３図の実験装置を用
いて、第１表に水質を示す下水処理場流入水を原水とし
て処理する。原水は４００１７日の流量で通水し、処理
水の加圧は２．０〜４．０　Ｋｑ／ｃｍ　２、加圧水量
は流入水の３０〜３００％、循環水量は原水量の４００
％、汚泥返送量は原水量の１００％、濃縮汚泥濃度は２
００００〜２５０００＋＋ｙ／ｌ、硝化・脱窒槽内汚泥
濃度は１００００〜１２０００η／ｌとして実験を行な
った。処理水の水質を第１表に示す。Using the experimental apparatus shown in FIG. 3, which has nitrification tanks of 6 volumes and 501 volumes, inflow water from a sewage treatment plant whose water quality is shown in Table 1 is treated as raw water. Raw water flows at a flow rate of 40,017 days, pressurization of treated water is 2.0 to 4.0 Kq/cm2, pressurized water volume is 30 to 300% of inflow water, and circulating water volume is 400% of raw water volume.
%, sludge return amount is 100% of raw water amount, thickened sludge concentration is 2
The experiment was conducted with the sludge concentration in the nitrification/denitrification tank set at 10,000 to 12,000 η/l. The quality of the treated water is shown in Table 1.

比較のため、前記と同じｄ量の槽を第１図に示したよう
に配列して実験したところ、返送汚泥濃度は８０００〜
１００００■／ｌとなり、槽内汚泥濃度は４０００〜５
０００■７１８度しか維持できなかった。そのため、原
水量を２００ｔ／日に半減させたところ、本発明方法と
同等の処理水Ｔ−Ｎ濃度（４，１〜６０■／／−）が得
られたが、沈殿池内で処理水中の残存ＮｏＸ−Ｎの脱窒
が起り、スカムで、本発明によれば第１図に示す従来法
の％〜’／２の容積で処理できる。For comparison, an experiment was conducted in which tanks with the same amount of d as above were arranged as shown in Figure 1, and the returned sludge concentration was 8000 ~
10,000■/l, and the sludge concentration in the tank is 4,000 to 5.
The temperature could only be maintained at 000■718 degrees. Therefore, when the amount of raw water was halved to 200 tons/day, the same concentration of T-N in the treated water as in the method of the present invention (4.1 to 60 μ//-) was obtained, but the residual Denitrification of NoX-N occurs and the scum can be treated according to the present invention with a volume of % to '/2 of the conventional method shown in FIG.

更に第２図に示した従来法を本発明方法と同一条件で実
験した。この従来法では、処理水ＳＳ濃度は低く良好で
あるが、処理水中のＴ　−Ｎは多く残留した。このＴ−
Ｎのうち、Ｎ０Ｘ−Ｎが８０〜９０％を占めており、脱
窒槽での脱窒が不完全であると考えられたので、脱窒槽
流出混合液のＮＯｘ−１寸濃度を測定したところ、ＮＯ
ゆ−Ｎが６〜１０ｍｇ　／　ｌ残存していた。１だ、Ｂ
ＯＤを測定すると、処理水ＢＯＤ濃度とほぼ同等であり
、空気を用いた加圧浮上汚泥中の酸素含有気泡によりＢ
ＯＤが好気的に消費されていることが判った。Furthermore, the conventional method shown in FIG. 2 was tested under the same conditions as the method of the present invention. In this conventional method, the SS concentration in the treated water was low and good, but a large amount of TN remained in the treated water. This T-
Of the N, NOX-N accounted for 80 to 90%, and it was thought that denitrification in the denitrification tank was incomplete, so we measured the NOx-1 concentration of the mixed solution flowing out of the denitrification tank. NO
6 to 10 mg/l of Yu-N remained. 1, B
When the OD is measured, it is almost the same as the BOD concentration of the treated water, and the BOD concentration is due to oxygen-containing bubbles in the pressurized floatation sludge.
It was found that OD was consumed aerobically.

本発明によれば、Ｔ−Ｎが著しく低下し、水質の良好な
処理水が得られた。According to the present invention, TN was significantly reduced and treated water with good water quality was obtained.

以上詳述したように、本発明により脱窒槽と浮上分離槽
を同一密閉室内に隣設させ、脱窒槽及び浮上分離槽上部
の脱窒素により生じた窒素ガスを含む気体を加圧して浮
上分離に用いることにより、脱窒槽においてＢＯＤを好
気的に分解することなく、有効に脱窒に利用することが
でき、かつ汚泥を画濃度に保持することができ、小容量
の反応槽で安定した処理を行なうことが可能になる。As detailed above, according to the present invention, a denitrification tank and a flotation tank are installed next to each other in the same sealed room, and gas containing nitrogen gas generated by denitrification in the upper part of the denitrification tank and flotation tank is pressurized to perform flotation separation. By using this method, BOD can be effectively used for denitrification without being aerobically decomposed in the denitrification tank, and the sludge can be maintained at a normal concentration, allowing stable treatment with a small-capacity reaction tank. It becomes possible to do this.

【図面の簡単な説明】[Brief explanation of drawings]

第１図及び第２図は従来法のフローンート、第３図は本
発明のフローノートである。符号の説明２・・・脱窒槽、　　　　　３・硝化槽、６・・・沈殿
池、　　　　　８−・浮上分離槽、９・加圧タンク、　
　１２・空気導入管、１５・・気体導出管。1 and 2 are flow notes of the conventional method, and FIG. 3 is a flow note of the present invention. Explanation of symbols 2--Denitrification tank, 3-Nitrification tank, 6-Sedimentation tank, 8--Flotation tank, 9-Pressure tank,
12. Air introduction pipe, 15. Gas discharge pipe.

Claims (2)

Translated fromJapanese

【特許請求の範囲】[Claims]（１）窒素化合物及び有機物を含む廃水を硝化工程及び
脱窒工程に導入し、脱窒工程で生じた気体を用いて加圧
浮上法により固液分離を行なうことを特徴とする廃水の
生物学的膝窒素方法。(1) Wastewater biology characterized by introducing wastewater containing nitrogen compounds and organic matter into a nitrification process and a denitrification process, and performing solid-liquid separation using the pressurized flotation method using the gas generated in the denitrification process. Target knee nitrogen method.（２）　　脱窒槽、硝化槽、固液分離槽及び固液分離槽
へ加圧水を供給する加圧タンクから成る廃水の生物学的
脱窒素装置において、脱窒槽と固液分離槽を同一密閉室
内に隣設させ、脱窒槽生成ガス導出管を加圧タンクと接
続したことを特徴とする廃水の生物学的脱窒素装置。(2) In a wastewater biological denitrification system consisting of a denitrification tank, a nitrification tank, a solid-liquid separation tank, and a pressurized tank that supplies pressurized water to the solid-liquid separation tank, the denitrification tank and the solid-liquid separation tank are placed in the same sealed room. A biological denitrification device for wastewater, which is installed adjacent to the denitrification tank, and a denitrification tank produced gas outlet pipe is connected to a pressurized tank.