JP4419418B2

JP4419418B2 - Nitrogen-containing wastewater treatment method

Info

Publication number: JP4419418B2
Application number: JP2003099399A
Authority: JP
Inventors: 信博織田
Original assignee: Kurita Water Industries Ltd
Current assignee: Kurita Water Industries Ltd
Priority date: 2003-04-02
Filing date: 2003-04-02
Publication date: 2010-02-24
Anticipated expiration: 2023-04-02
Also published as: JP2004305814A

Description

【０００１】
【発明の属する技術分野】
本発明は窒素含有排水の処理方法に係り、特にアンモニア性窒素を酸化し次いで脱窒する工程を有する窒素含有排水の処理方法に関する。詳しくは、本発明は、排水中にヒドラジン、ヒドロキシルアミン、過酸化水素などのアンモニア酸化細菌の生育を阻害する生育阻害物質が含まれる場合に採用される窒素含有排水の処理方法に関する。
【０００２】
【従来の技術】
排液中に含まれるアンモニア性窒素は河川、湖沼及び海洋などにおける富栄養化の原因物質の一つであり、排液処理工程で効率的に除去する必要がある。一般に、排水中のアンモニア性窒素は、アンモニア性窒素をアンモニア酸化細菌により亜硝酸性窒素に酸化し、更にこの亜硝酸性窒素を亜硝酸酸化細菌により硝酸性窒素に酸化する硝化工程と、これらの亜硝酸性窒素及び硝酸性窒素を従属栄養性細菌である脱窒菌により、有機物を電子供与体として利用して窒素ガスにまで分解する脱窒工程との２段階の生物反応を経て窒素ガスにまで分解される。
【０００３】
しかし、このような従来の硝化脱窒法では、脱窒工程において電子供与体としてメタノールなどの有機物を多量に必要とし、また硝化工程では多量の酸素が必要であるため、ランニングコストが高いという欠点がある。
【０００４】
これに対して、近年、アンモニア性窒素を電子供与体とし、亜硝酸性窒素を電子受容体とする独立栄養性細菌（自己栄養細菌）を利用し、アンモニア性窒素と亜硝酸性窒素とを反応させて脱窒する方法が提案された。この方法であれば、有機物の添加は不要であるため、従属栄養性の脱窒菌を利用する方法と比べて、コストを低減することができる。また、独立栄養性の細菌は収率が低く、汚泥の発生量が従属栄養性細菌と比較すると著しく少ないので、余剰汚泥の発生量を抑えることができる。更に、従来の硝化脱窒法で観察されるＮ_２Ｏの発生がなく、環境に対する負荷を低減できるといった特長もある。
【０００５】
この独立栄養性脱窒細菌（以下「ＡＮＡＭＭＯＸ菌」と称す場合がある。）を利用する生物脱窒プロセスは、Strous, M et al. (1998) Appl. Microbiol. Biotechnol.Vol.50,p.589-596に報告されており、以下のような反応でアンモニア性窒素と亜硝酸性窒素が反応して窒素ガスに分解されると考えられている。
【０００６】
【化１】

【０００７】
即ち、ＡＮＡＭＭＯＸ菌を利用して脱窒処理を行う場合、ＡＮＡＭＭＯＸ菌を保持するＡＮＡＭＭＯＸ反応槽に流入する被処理水（原水）は、アンモニア性窒素と亜硝酸性窒素を含む必要がある。このため、従来においては、例えば、アンモニア性窒素を含む排水を予め硝化処理し、排水中のアンモニア性窒素の一部をアンモニア酸化細菌により亜硝酸性窒素に酸化したものを原水として導入している。この原水は、上記反応式から明らかなように、アンモニア性窒素と亜硝酸性窒素とがモル比０．４３：０．５７で反応するため、アンモニア性窒素（ＮＨ_４−Ｎ）と亜硝酸性窒素（ＮＯ_２−Ｎ）をこのような割合で含むことが好ましい。
【０００８】
なお、反応生成物として窒素の他に硝酸が生成するため、ＡＮＡＭＭＯＸ工程の後段にメタノール等の有機物の共存下で生物脱窒を行う脱窒工程を設けることにより、窒素の除去率を高め、良好な水質の処理水を得ることができる。
【０００９】
【非特許文献１】
Strous, M et al. (1998) Appl. Microbiol.
Biotechnol.Vol.50, p.589-596
【００１０】
【発明が解決しようとする課題】
窒素含有排水には、ヒドラジン、ヒドロキシルアミン、過酸化水素などアンモニア酸化細菌の生育阻害を引き起こすものを含むものがある。
【００１１】
従来、この生育阻害物質含有排水を処理する場合は、ヒドラジンなどの生育阻害物質を分解除去、あるいは生育阻害濃度以下に希釈した後、硝化槽へ流入させている。この生育阻害物質の分解方法としては、アルカリ注入・高ｐＨ条件下で硫酸銅触媒を用いて分解する方法が行われている。
【００１２】
しかし、硫酸銅も生育阻害性を有すると共に、排水規制のため除去する必要があり、装置・操作が煩雑となり、処理費用も高価となる問題があった。
【００１３】
本発明は上記従来の問題点を解決し、ヒドラジン、ヒドロキシルアミン、過酸化水素などアンモニア酸化細菌の生育を阻害する生育阻害物質を含む窒素含有排水を容易に処理する方法を提供することを目的とする。
【００１４】
【課題を解決するための手段】
第１発明（請求項１）の窒素含有排水の処理方法は、アンモニア性窒素を含有する窒素含有排水と、アンモニア酸化細菌の生育を阻害する生育阻害物質を含有する生育阻害物質含有排水とを処理する窒素含有排水の処理方法であって、該窒素含有排水を亜硝酸化処理する亜硝酸化工程と、該亜硝酸化工程からの亜硝酸含有水を脱窒処理する脱窒工程と、前記生育阻害物質含有排水に対し亜硝酸を添加し、亜硝酸と生育阻害物質含有排水中の生育阻害物質とを反応させて生育阻害物質を分解する生育阻害物質分解工程と、該分解工程からの分解処理水を前記亜硝酸化工程及び／又は脱窒工程に供給する工程と、を有し、該生育阻害物質がヒドラジンであり、該生育阻害物質含有排水に亜硝酸を添加するために、前記亜硝酸化工程からの亜硝酸含有水の一部を前記生育阻害物質分解工程に添加するものである。
【００１５】
第２発明の請求項２の窒素含有排水の処理方法は、アンモニア性窒素とアンモニア酸化細菌生育阻害物質とを含有する排水を処理する方法であって、該排水に亜硝酸を添加して生育阻害物質を分解する生育阻害物質分解工程と、該生育阻害物質分解工程からの分解処理水を亜硝酸化処理及び／又は硝酸化処理する酸化工程と、該酸化工程からの酸化処理水を脱窒処理する脱窒工程とを有し、該生育阻害物質がヒドラジンであり、前記排水に亜硝酸を添加するために、前記生育阻害物質分解工程からの分解処理水の一部を亜硝酸化処理して亜硝酸含有水とする亜硝酸化工程を有し、該亜硝酸化工程からの亜硝酸含有水を前記排水に添加し、前記生育阻害物質分解工程からの分解処理水の残部を前記酸化工程に導入するものである。
また、請求項３の窒素含有排水の処理方法は、アンモニア性窒素とアンモニア酸化細菌生育阻害物質とを含有する排水を処理する方法であって、該排水に亜硝酸を添加して生育阻害物質を分解する生育阻害物質分解工程と、該生育阻害物質分解工程からの分解処理水を亜硝酸化処理する亜硝酸化工程と、該亜硝酸化工程からの亜硝酸化処理水を脱窒処理する脱窒工程とを有し、該生育阻害物質がヒドラジンであり、前記排水に亜硝酸を添加するために、前記亜硝酸化工程の亜硝酸化処理水の一部を前記排水に添加し、該亜硝酸化処理水の残部を前記脱窒工程に導入するものである。
【００１６】
上記の通り、アンモニア性窒素含有排水が生物酸化処理されると、亜硝酸イオンが生成すると共に、この亜硝酸イオンがさらに酸化されて硝酸イオンが生成する。
【００１７】
本発明者が研究を重ねた結果、この生物酸化処理によって生成する亜硝酸がヒドラジン、ヒドロキシルアミン、過酸化水素などのアンモニア酸化細菌生育阻害物質と反応してこれを分解することが見出された。
【００１８】
本発明は、かかる知見に基づき創案されたものであり、本発明によれば、生育阻害物質が亜硝酸によって効率良く分解されることにより、排水中の生育阻害物質と窒素とを効率良く低コストに処理することが可能となる。
【００１９】
なお、上記のヒドラジン含有排水としては発電所の復水脱塩装置再生排水、ボイラ蒸発管の保管排水、ヒドラジン製造工場排水などが例示され、ヒドロキシルアミン含有排水としてはヒドロキシルアミン製造工場排水、ＬＳＩ製造工場（レジストの剥離）排水などが例示され、過酸化水素含有排水としてはＬＳＩ製造工場（レジストの剥離）排水、食品、繊維、紙パルプの殺菌・脱色後の排水などが例示される。窒素含有排水としては、し尿、生活排水、農業排水、工業排水、食品工場排水、コンデミ再生排水などが例示される。窒素と生育阻害物質とを含有する排水としては、窒素とヒドラジンとを含有する上記復水脱塩装置再生排水、上記各排水の混合排水などが例示される。
【００２０】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態について詳細に説明する。
【００２１】
図１（ａ）は、生育阻害物質含有排水と窒素含有排水とを処理する実施の形態に係る方法のフロー図である。
【００２２】
窒素含有排水は、酸化槽１に導入され、亜硝酸化処理又は亜硝酸化及び硝酸化処理され、一部の亜硝酸含有水は混合反応槽２へ送られ、残部は脱窒処理槽３へ送られて脱窒処理され、処理水となる。生育阻害物質含有排水は、該混合反応槽２にて酸化槽１からの亜硝酸イオン含有水が混合され、生育阻害物質が分解処理される。この混合反応槽２の分解処理水は、脱窒処理槽３へ送られ、脱窒処理される。
【００２３】
この脱窒処理槽３は、亜硝酸性窒素及び硝酸性窒素を従属栄養性細菌である脱窒菌により、有機物を電子供与体として利用して窒素ガスにまで分解する脱窒菌脱窒プロセスを行うものであってもよく、アンモニア性窒素を電子供与体とし、亜硝酸性窒素を電子受容体とする独立栄養性微生物すなわちＡＮＡＭＭＯＸ菌を利用し、アンモニア性窒素と亜硝酸性窒素とを反応させて脱窒するＡＮＡＭＭＯＸプロセスであってもよい。
【００２４】
この脱窒処理槽３が、上記の脱窒菌脱窒プロセスを行うものである場合、酸化槽１の流出水中にアンモニアが残留しないようにするために、図１（ｄ）のように酸化槽１から脱窒槽３へ向けて流出する流出水の一部を該酸化槽１に循環させて硝化を十分に進行させるようにしてもよい。
【００２５】
脱窒処理槽３がＡＮＡＭＭＯＸプロセスを行うものであるときには、酸化槽１の流出水中にはアンモニアが残留する方が好ましく、特に、生育阻害物質含有排水中にアンモニアが含有されないときには、酸化槽流出水中にアンモニアを残留させる必要がある。
【００２６】
なお、前述の通り、ＡＮＡＭＭＯＸ工程の処理水中には硝酸性窒素が残留することが多い。
【００２７】
ＡＮＡＭＭＯＸ工程の処理水中に残留した硝酸性窒素を除去するためにＡＮＡＭＭＯＸ工程の後段に、メタノール等の有機物の共存下で生物脱窒させる脱窒菌脱窒プロセスを行ってもよい。
【００２８】
図１（ａ），（ｄ）では混合反応槽２の流出水の全量を脱窒処理槽３へ供給しているが、図１（ｂ）のように混合反応槽２の流出水の全量を酸化槽１へ供給してもよく、図１（ｃ）のように混合反応槽２の流出水の一部を酸化槽１へ供給し、残部を脱窒処理槽３へ供給してもよい。図１（ｂ），（ｃ）の場合においても、図１（ｄ）の如く酸化槽１から脱窒処理槽３へ向けて流出する流出水の一部を酸化槽１へ循環させてもよい。
【００２９】
図２は、生育阻害物質及び窒素を含む排水を処理する方法のフロー図である。図２（ａ）では、この生育阻害物質・窒素含有排水は、混合反応槽２にて亜硝酸イオンの添加・混合により生育阻害物質が分解された後、酸化槽１にて亜硝酸化処理又は亜硝酸化及び硝酸化処理された後、脱窒処理槽３にて脱窒処理される。この脱窒処理槽３は、図１の場合と同じく脱窒菌による脱窒プロセスであってもよくＡＮＡＭＭＯＸ菌による脱窒プロセスであってもよい。後者のＡＮＡＭＭＯＸ脱窒プロセスの場合、脱窒処理槽３の後段に脱窒菌による脱窒槽を設けてもよい。
【００３０】
図２（ａ）では、混合反応槽２に亜硝酸イオンを供給するために、混合反応槽２からの流出水の一部を亜硝酸化槽４へ導入し、亜硝酸化処理して亜硝酸イオンを生成させ、この亜硝酸イオンを含む水を混合反応槽２へ添加している。
【００３１】
また、運転開始の当初だけ亜硝酸イオン供給源から混合反応槽２へ亜硝酸イオンを供給し、酸化槽１の酸化反応が十分に進行するようになった段階になったならば、図２（ｂ）のように該酸化槽１の酸化処理水の一部を混合反応槽２に供給し、該酸化処理水中の亜硝酸イオンを生育阻害物質の分解に利用するようにしてもよい。
【００３２】
脱窒処理槽３が、前述の脱窒菌による脱窒プロセスを行うものである場合、酸化槽１からこの脱窒処理槽３に導入される酸化処理水はアンモニアが残留しないように硝化が進行していることが好ましい。そこで、この場合には、図２（ｃ）のように酸化槽１から脱窒処理槽３へ向って流出する流出水の一部を酸化槽１へ循環させるようにしてもよい。
【００３３】
【実施例】
以下に比較例及び実施例を挙げて本発明をより具体的に説明する。
【００３４】
＜比較例１＞
アンモニア性窒素７００ｍｇ−Ｎ／Ｌとヒドラジン性窒素３０ｍｇ−Ｎ／Ｌを含む復水脱塩装置（コンデミ）再生排水を中和した排水を原水とした。この排水を生物（硝化）槽へ導入したところ、曝気槽が泡立ち、汚泥が白色化して、アンモニアが酸化されなくなった。亜硝酸化、硝酸化が起こらないため、脱窒できなかった。
【００３５】
＜比較例２＞
上記排水中のヒドラジンを分解するため、硫酸銅を排水中の濃度が１０ｍｇ／Ｌとなるように添加し、ｐＨ１０に調整し、１時間曝気処理した。この処理で、ヒドラジンは５ｍｇ／Ｌ以下となったが、Ｃｕイオンがアンモニア錯体として１ｍｇ／Ｌ程度残留し、このＣｕイオンの阻害のため、硝化速度が３０％程度低下した。
【００３６】
＜実施例１＞
上記原水を図２（ｂ）に示す構成の装置に８００Ｌ／ｄａｙにて通水して処理した。各槽の内容は次の通りである。

【００３７】
初期には混合反応槽へ亜硝酸ナトリウムを５０ｍｇ−Ｎ／Ｌの濃度となるように添加したところ、混合反応槽２の流出水中のヒドラジンは１ｍｇ−Ｎ／Ｌ以下となった。
【００３８】
ヒドラジンを除去したため、酸化槽１は安定運転できた。３０分経過後、酸化槽で生成した亜硝酸性窒素を混合反応槽へ返送・添加するようにした。この場合も、ヒドラジンが酸化槽へ流入せず、安定運転することができた。
【００３９】
【発明の効果】
以上詳述した通り、本発明の窒素含有排水の処理方法によれば、アンモニア性窒素及びアンモニア酸化細菌生育阻害物質を含む原水を簡易なプロセスにより処理して高い窒素除去率を安定して得ることが可能となる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係る窒素含有排水の処理方法の系統図である。
【図２】本発明の別の実施の形態に係る窒素含有排水の処理方法の系統図である。
【符号の説明】
１酸化槽
２混合反応槽
３脱窒処理槽
４亜硝酸化槽[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating nitrogen-containing wastewater, and more particularly, to a method for treating nitrogen-containing wastewater having a step of oxidizing ammonia nitrogen and then denitrifying. Specifically, the present invention relates to a method for treating nitrogen-containing wastewater that is employed when the wastewater contains a growth inhibitory substance that inhibits the growth of ammonia-oxidizing bacteria such as hydrazine, hydroxylamine, and hydrogen peroxide.
[0002]
[Prior art]
Ammonia nitrogen contained in the effluent is one of the causative substances of eutrophication in rivers, lakes and oceans, and it is necessary to remove it efficiently in the effluent treatment process. In general, ammonia nitrogen in wastewater is oxidized by ammonia oxidizing bacteria to nitrite nitrogen, and nitrifying nitrogen is oxidized to nitrate nitrogen by nitrite oxidizing bacteria. Nitrite nitrogen and nitrate nitrogen are denitrified bacteria, which are heterotrophic bacteria, and are converted into nitrogen gas through a two-stage biological reaction with a denitrification process that decomposes organic matter into nitrogen gas using an electron donor. Disassembled.
[0003]
However, such a conventional nitrification denitrification method requires a large amount of organic matter such as methanol as an electron donor in the denitrification step, and also requires a large amount of oxygen in the nitrification step, so that the running cost is high. is there.
[0004]
In contrast, in recent years, ammonia nitrogen and nitrite nitrogen are reacted using autotrophic bacteria (autotrophic bacteria) using ammonia nitrogen as an electron donor and nitrite nitrogen as an electron acceptor. A method of denitrifying by letting go was proposed. If this method is used, it is not necessary to add an organic substance, so that the cost can be reduced as compared with a method using heterotrophic denitrifying bacteria. Moreover, since the yield of autotrophic bacteria is low and the amount of sludge generated is significantly less than that of heterotrophic bacteria, the amount of surplus sludge generated can be suppressed. Furthermore, there is also a feature that there is no generation of N ₂ O observed by the conventional nitrification denitrification method, and the burden on the environment can be reduced.
[0005]
A biological denitrification process using this autotrophic denitrifying bacterium (hereinafter sometimes referred to as “ANAMOX bacteria”) is described in Strous, M et al. (1998) Appl. Microbiol. Biotechnol. Vol.50, p. 589-596, it is considered that ammonia nitrogen and nitrite nitrogen react and decompose into nitrogen gas in the following reaction.
[0006]
[Chemical 1]

[0007]
That is, when performing a denitrification process using ANAMMOX bacteria, the to-be-processed water (raw water) which flows into the ANAMMOX reaction tank holding ANAMOX bacteria needs to contain ammonia nitrogen and nitrite nitrogen. For this reason, conventionally, for example, wastewater containing ammonia nitrogen is nitrified in advance, and a portion of ammonia nitrogen in the waste water is oxidized into nitrite nitrogen by ammonia oxidizing bacteria as raw water. . As apparent from the above reaction formula, this raw water reacts with ammonia nitrogen (NH ₄ -N) and nitrite since ammonia nitrogen and nitrite nitrogen react at a molar ratio of 0.43: 0.57. Nitrogen (NO ₂ —N) is preferably contained in such a ratio.
[0008]
Since nitric acid is produced in addition to nitrogen as a reaction product, a nitrogen removal rate is improved by providing a denitrification step that performs biological denitrification in the coexistence of organic substances such as methanol after the ANAMOX step. Treated water with high water quality can be obtained.
[0009]
[Non-Patent Document 1]
Strous, M et al. (1998) Appl. Microbiol.
Biotechnol.Vol.50, p.589-596
[0010]
[Problems to be solved by the invention]
Some nitrogen-containing wastewater includes those that cause growth inhibition of ammonia-oxidizing bacteria such as hydrazine, hydroxylamine, and hydrogen peroxide.
[0011]
Conventionally, when treating this growth inhibitory substance-containing wastewater, growth inhibitory substances such as hydrazine are decomposed and removed or diluted to a growth inhibitory concentration or less and then flowed into the nitrification tank. As a method for decomposing this growth inhibitory substance, a method of decomposing using a copper sulfate catalyst under alkali injection and high pH conditions is performed.
[0012]
However, copper sulfate also has growth inhibitory properties and needs to be removed for drainage regulation, which causes problems that the apparatus and operation become complicated and the processing cost is high.
[0013]
An object of the present invention is to solve the above conventional problems and to provide a method for easily treating nitrogen-containing wastewater containing a growth inhibitory substance that inhibits the growth of ammonia-oxidizing bacteria such as hydrazine, hydroxylamine, and hydrogen peroxide. To do.
[0014]
[Means for Solving the Problems]
The method for treating nitrogen-containing wastewater of the first invention (invention 1) treats nitrogen-containing wastewater containing ammoniacal nitrogen and growth-inhibiting substance-containing wastewater containing growth inhibitory substances that inhibit the growth of ammonia-oxidizing bacteria. A method for treating nitrogen-containing wastewater, comprising a nitritation step for nitrifying the nitrogen-containing wastewater, a denitrification step for denitrifying nitrous acid-containing water from the nitritation step, and the growth A growth inhibitory substance decomposition step for decomposing a growth inhibitory substance by adding nitrous acid to the inhibitory substance containing wastewater and reacting the nitrous acid with the growth inhibitory substance in the growth inhibitory substance containing wastewater, and a decomposition treatment from the decomposition step water have a, and supplying the nitrite step and / or denitrification step, a biological education inhibitor hydrazine, for adding nitrite to the biological education inhibitor-containing waste water, wherein the nitrite Containing nitrous acid Part of the water is intended to be added to the growth inhibitory substance decomposition step.
[0015]
Method of treating nitrogen-containing wastewater according to claim 2 of the second invention is a method of treating a wastewater containing ammonia nitrogen and ammonia oxidizing bacteria growth inhibitor, growth inhibition by the addition of nitrite to drainage Growth inhibiting substance decomposition process for decomposing substances, oxidation process for decomposing and / or nitrating decomposition water from the growth inhibiting substance decomposition process, and denitrification treatment for oxidation treated water from the oxidation process A denitrification step, wherein the growth inhibitory substance is hydrazine, and in order to add nitrous acid to the waste water, a part of the decomposition treated water from the growth inhibitory substance decomposition step is subjected to a nitrite treatment. A nitritation step for converting the nitrite into water, adding the nitrite-containing water from the nitritation step to the waste water, and the rest of the decomposition treated water from the growth inhibitor decomposition step to the oxidation step It is to be introduced .
The method for treating nitrogen-containing wastewater according to claim 3 is a method for treating wastewater containing ammoniacal nitrogen and an ammonia-oxidizing bacteria growth inhibitory substance, and adding nitrous acid to the wastewater to remove the growth inhibitory substance. A growth inhibiting substance decomposition step for decomposing, a nitritation step for denitrifying the decomposition treated water from the growth inhibiting substance decomposing step, and a denitrifying treatment for denitrifying the nitritized water from the nitrating step A nitrification step, wherein the growth inhibitor is hydrazine, and in order to add nitrous acid to the wastewater, a part of the nitritation water of the nitritation step is added to the wastewater, The remainder of the nitrating water is introduced into the denitrification step.
[0016]
As described above, when the ammoniacal nitrogen-containing wastewater is subjected to biological oxidation treatment, nitrite ions are generated, and the nitrite ions are further oxidized to generate nitrate ions.
[0017]
As a result of repeated studies by the present inventor, it was found that nitrous acid produced by this biological oxidation treatment reacts with and decomposes ammonia-oxidizing bacterial growth inhibitors such as hydrazine, hydroxylamine, and hydrogen peroxide. .
[0018]
The present invention was devised based on such knowledge, and according to the present invention, the growth inhibitory substance and nitrogen in the waste water are efficiently and low-cost by the growth inhibitory substance being efficiently decomposed by nitrous acid. Can be processed.
[0019]
Examples of hydrazine-containing wastewater include power plant condensate demineralizer regeneration wastewater, boiler evaporator tube storage wastewater, hydrazine production plant wastewater, and the like. Hydroxylamine-containing wastewater includes hydroxylamine production plant wastewater and LSI manufacturing. Examples include factory (resist stripping) wastewater, and examples of the hydrogen peroxide-containing wastewater include LSI manufacturing factory (resist stripping) wastewater, wastewater after sterilization and decolorization of food, fiber, and paper pulp. Examples of nitrogen-containing wastewater include human waste, domestic wastewater, agricultural wastewater, industrial wastewater, food factory wastewater, and condensate regeneration wastewater. Examples of the wastewater containing nitrogen and growth inhibitory substances include the above-described condensate demineralizer regeneration wastewater containing nitrogen and hydrazine, and the mixed wastewater of each of the above wastewater.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0021]
Fig.1 (a) is a flowchart of the method which concerns on embodiment which processes the growth inhibitory substance containing waste_water | drain and nitrogen containing waste_water | drain.
[0022]
Nitrogen-containing wastewater is introduced into the oxidation tank 1 and subjected to nitritation treatment or nitritation and nitrification treatment, a part of the nitrite-containing water is sent to the mixing reaction tank 2 and the remainder to the denitrification treatment tank 3 It is sent and denitrified, and becomes treated water. The growth inhibitory substance-containing wastewater is mixed with nitrite ion-containing water from the oxidation tank 1 in the mixing reaction tank 2 to decompose the growth inhibitory substance. The decomposition treated water in the mixed reaction tank 2 is sent to the denitrification treatment tank 3 and denitrified.
[0023]
This denitrification treatment tank 3 performs a denitrification denitrification process in which nitrite nitrogen and nitrate nitrogen are decomposed to nitrogen gas by using organic matter as an electron donor by denitrifying bacteria as heterotrophic bacteria. It is also possible to use an autotrophic microorganism that has ammonia nitrogen as an electron donor and nitrite nitrogen as an electron acceptor, ie, ANAMMOX bacteria, and reacts ammonia nitrogen with nitrite nitrogen to remove it. It may also be a Nimmox process for nitriding.
[0024]
When this denitrification treatment tank 3 performs the above denitrification bacteria denitrification process, in order to prevent ammonia from remaining in the effluent water of the oxidation tank 1, the oxidation tank 1 as shown in FIG. Alternatively, a part of the effluent that flows out from the denitrification tank 3 may be circulated to the oxidation tank 1 so that nitrification proceeds sufficiently.
[0025]
When the denitrification treatment tank 3 performs the ANAMMOX process, it is preferable that ammonia remains in the effluent of the oxidation tank 1, and particularly when no ammonia is contained in the waste water containing the growth inhibitory substance, the effluent from the oxidation tank. It is necessary to leave ammonia.
[0026]
As described above, nitrate nitrogen often remains in the treated water of the ANAMOX process.
[0027]
In order to remove nitrate nitrogen remaining in the treated water of the ANAMOX process, a denitrifying bacteria denitrification process in which biological denitrification is performed in the presence of an organic substance such as methanol may be performed after the ANAMOX process.
[0028]
1 (a) and 1 (d), the total amount of effluent water from the mixing reaction tank 2 is supplied to the denitrification tank 3, but the total amount of effluent water from the mixing reaction tank 2 as shown in FIG. 1 (b). It may be supplied to the oxidation tank 1 or a part of the effluent of the mixed reaction tank 2 may be supplied to the oxidation tank 1 and the remaining part may be supplied to the denitrification treatment tank 3 as shown in FIG. In the case of FIGS. 1B and 1C as well, a part of the effluent flowing out from the oxidation tank 1 toward the denitrification treatment tank 3 may be circulated to the oxidation tank 1 as shown in FIG. .
[0029]
FIG. 2 is a flow diagram of a method for treating wastewater containing growth inhibitory substances and nitrogen. In FIG. 2 (a), this growth inhibitory substance / nitrogen-containing wastewater is subjected to nitritation treatment or oxidation in the oxidation tank 1 after the growth inhibitory substance is decomposed by the addition / mixing of nitrite ions in the mixing reaction tank 2. After nitritation and nitrification treatment, denitrification treatment is performed in the denitrification treatment tank 3. The denitrification treatment tank 3 may be a denitrification process using denitrifying bacteria as in the case of FIG. 1 or a denitrification process using ANAMMOX bacteria. In the case of the latter ANAMOX denitrification process, a denitrification tank with denitrifying bacteria may be provided at the subsequent stage of the denitrification treatment tank 3.
[0030]
In FIG. 2 (a), in order to supply nitrite ions to the mixing reaction tank 2, a part of the effluent water from the mixing reaction tank 2 is introduced into the nitritation tank 4 and subjected to nitritation treatment to nitrous acid. Ions are generated, and water containing the nitrite ions is added to the mixing reaction tank 2 .
[0031]
Further, when nitrite ions are supplied from the nitrite ion supply source to the mixed reaction tank 2 only at the beginning of the operation and the oxidation reaction in the oxidation tank 1 is sufficiently advanced, FIG. As shown in b), a part of the oxidation-treated water in the oxidation tank 1 may be supplied to the mixing reaction tank 2, and nitrite ions in the oxidation-treated water may be used for decomposition of the growth inhibitory substance.
[0032]
When the denitrification treatment tank 3 performs the above-mentioned denitrification process using the denitrification bacteria, the oxidation treatment water introduced from the oxidation tank 1 to the denitrification treatment tank 3 proceeds with nitrification so that ammonia does not remain. It is preferable. Therefore, in this case, as shown in FIG. 2C, a part of the effluent that flows out from the oxidation tank 1 toward the denitrification treatment tank 3 may be circulated to the oxidation tank 1.
[0033]
【Example】
Hereinafter, the present invention will be described more specifically with reference to comparative examples and examples.
[0034]
<Comparative Example 1>
Waste water obtained by neutralizing condensate demineralizer (condemi) regeneration waste water containing 700 mg-N / L ammoniacal nitrogen and 30 mg-N / L hydrazine nitrogen was used as raw water. When this wastewater was introduced into the biological (nitrification) tank, the aeration tank was foamed, the sludge was whitened, and ammonia was not oxidized. Denitrification was not possible because nitritation and nitrification did not occur.
[0035]
<Comparative example 2>
In order to decompose hydrazine in the waste water, copper sulfate was added so that the concentration in the waste water was 10 mg / L, adjusted to pH 10, and aerated for 1 hour. By this treatment, hydrazine was reduced to 5 mg / L or less, but Cu ions remained as 1 mg / L as an ammonia complex, and the nitrification rate was reduced by about 30% due to inhibition of Cu ions.
[0036]
<Example 1>
The raw water was treated by passing water at 800 L / day through an apparatus having the configuration shown in FIG. The contents of each tank are as follows.

[0037]
Initially, sodium nitrite was added to the mixing reaction tank to a concentration of 50 mg-N / L. As a result, the amount of hydrazine in the effluent of the mixing reaction tank 2 became 1 mg-N / L or less.
[0038]
Since hydrazine was removed, the oxidation tank 1 was able to operate stably. After 30 minutes, the nitrite nitrogen produced in the oxidation tank was returned and added to the mixing reaction tank. Also in this case, hydrazine did not flow into the oxidation tank, and stable operation was possible.
[0039]
【The invention's effect】
As described above in detail, according to the method for treating nitrogen-containing wastewater of the present invention, a high nitrogen removal rate can be stably obtained by treating raw water containing ammonia nitrogen and an ammonia-oxidizing bacteria growth inhibitory substance by a simple process. Is possible.
[Brief description of the drawings]
FIG. 1 is a system diagram of a method for treating nitrogen-containing wastewater according to an embodiment of the present invention.
FIG. 2 is a system diagram of a method for treating nitrogen-containing wastewater according to another embodiment of the present invention.
[Explanation of symbols]
1 Oxidation tank 2 Mixed reaction tank 3 Denitrification tank 4 Nitrite tank

Claims

A nitrogen-containing wastewater treatment method for treating a nitrogen-containing wastewater containing ammonia nitrogen and a growth-inhibiting substance-containing wastewater containing a growth inhibitory substance that inhibits the growth of ammonia-oxidizing bacteria,
A nitritation step of nitrifying the nitrogen-containing wastewater;
A denitrification step of denitrifying the nitrite-containing water from the nitritation step;
A growth inhibiting substance decomposition step of decomposing the growth inhibiting substance by adding nitrous acid to the growth inhibiting substance-containing wastewater and reacting the nitrite with the growth inhibiting substance in the growth inhibiting substance-containing wastewater;
Supplying the decomposition-treated water from the decomposition step to the nitritation step and / or denitrification step;
Have
The growth inhibitor is hydrazine;
A method for treating nitrogen-containing wastewater, wherein a portion of the nitrite-containing water from the nitritation step is added to the growth-inhibitory substance decomposition step in order to add nitrous acid to the growth-inhibitory agent-containing wastewater.

A method for treating wastewater containing ammonia nitrogen and an ammonia-oxidizing bacterial growth inhibitor,
A growth inhibiting substance decomposition step of decomposing the growth inhibiting substance by adding nitrous acid to the waste water;
An oxidation step of nitrating and / or nitrating the decomposition treated water from the growth inhibiting substance decomposition step;
A denitrification step of denitrifying the oxidized water from the oxidation step,
The growth inhibitor is hydrazine;
In order to add nitrous acid to the waste water, a nitrification step is performed in which a part of the decomposition treated water from the growth inhibiting substance decomposition step is subjected to nitrification treatment to obtain nitrite-containing water , A method for treating nitrogen-containing wastewater , wherein nitrous acid-containing water from a step is added to the wastewater, and the remainder of the decomposition-treated water from the growth-inhibiting substance decomposition step is introduced into the oxidation step .

A method for treating wastewater containing ammonia nitrogen and an ammonia-oxidizing bacterial growth inhibitor,
A growth inhibiting substance decomposition step of decomposing the growth inhibiting substance by adding nitrous acid to the waste water;
And nitrous oxide step you nitritation processing decomposition process water from the biological education inhibitor decomposition step,
And a denitrification step of denitrification of nitrite oxidation treated water from the nitrous oxide process,
The growth inhibitor is hydrazine;
To nitrite is added to the waste water, nitrogen before adding a portion of the nitrous acid treatment water Kia nitrating step in the waste water, to introduce the remainder of the nitrous nitrate process water to the denitrification step Treatment method of contained wastewater.