JP2003053384A - Method for removing nitrogen and phosphorus from waste water and facility therefor - Google Patents
Method for removing nitrogen and phosphorus from waste water and facility thereforInfo
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- JP2003053384A JP2003053384A JP2001252413A JP2001252413A JP2003053384A JP 2003053384 A JP2003053384 A JP 2003053384A JP 2001252413 A JP2001252413 A JP 2001252413A JP 2001252413 A JP2001252413 A JP 2001252413A JP 2003053384 A JP2003053384 A JP 2003053384A
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- phosphorus
- redox potential
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Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は,廃水中に含まれる
窒素・リンを安定的かつ効率的に除去することを目的と
する。TECHNICAL FIELD The present invention has an object to stably and efficiently remove nitrogen / phosphorus contained in wastewater.
【0002】[0002]
【従来の技術】まず,窒素の除去に関する従来技術を説
明する。廃水中の窒素は,アンモニア性窒素,又は,硝
酸性窒素の形で含有されることが多い。アンモニア性窒
素を含有する廃水は,都市下水,屎尿,製鉄所コークス
工場廃水,肥料工場廃水,半導体工場廃水,皮革工場廃
水などがある。特に,製鉄所コークス工場から発生する
アンモニア性窒素含有廃水は,安水とも呼ばれ,アンモ
ニア性窒素を数百−数千mg/l程度も含有している。
また,アンモニア性窒素ではなく硝酸性窒素を含有する
例としては,ステンレス鋼板洗浄廃水や農薬で汚染され
た地下水などがある。2. Description of the Related Art First, a conventional technique for removing nitrogen will be described. Nitrogen in wastewater is often contained in the form of ammoniacal nitrogen or nitrate nitrogen. Wastewater containing ammoniacal nitrogen includes municipal wastewater, human waste, ironworks coke factory wastewater, fertilizer factory wastewater, semiconductor factory wastewater, leather factory wastewater, and the like. In particular, the ammoniacal nitrogen-containing wastewater generated from the coke plant of a steel mill is also called “ammonium” and contains ammoniacal nitrogen of about several hundreds to several thousands mg / l.
In addition, examples containing nitric acid nitrogen instead of ammonia nitrogen include stainless steel plate washing wastewater and groundwater contaminated with pesticides.
【0003】廃水からの窒素の除去方法としては,以下
のような生物学的硝化−脱窒素法が広く知見されてい
る。これは,絶対好気性・独立栄養細菌(Nitrosomona
s,Nitrobacter等の硝化細菌)による生物学的酸化反応
と通性嫌気性・従属栄養細菌(Pseudomonas等)による
生物学的還元反応の組み合わせから成っている。As a method of removing nitrogen from wastewater, the following biological nitrification-denitrification method is widely known. This is an absolute aerobic / autotrophic bacterium (Nitrosomona
s, Nitrobacter and other nitrifying bacteria) and biological reduction reactions by facultative anaerobic / heterotrophic bacteria (Pseudomonas, etc.).
【0004】まず,硝化工程は以下の2段の反応から成
っており,関与する硝化細菌の種類は異なっている。
2NH4 + + 3O2 → 2NO2 -+2H2O+4H+ (1)
2NO2 - + O2 → 2NO3 - (2)
(1)式に示す反応は,Nitrosomonasを代表種とするア
ンモニア酸化細菌によってもたらされ,(2)式に示す
反応は,Nitrobacterを代表種とする亜硝酸酸化細菌に
よってもたらされる。First, the nitrification process consists of the following two-step reactions, and the types of nitrifying bacteria involved are different. 2NH 4 + + 3O 2 → 2NO 2 - + 2H 2 O + 4H + (1) 2NO 2 - + O 2 → 2NO 3 - (2) (1) reaction shown in expression by ammonium oxidizing bacteria typified species Nitrosomonas The reaction represented by the formula (2) is brought about by the nitrite-oxidizing bacteria represented by Nitrobacter.
【0005】次に脱窒工程であるが,上記反応によって
生成した亜硝酸性窒素並びに硝酸性窒素は,通性嫌気性
従属栄養細菌を用いて,無酸素の条件下で,以下のよう
に還元されて酸化窒素ガス(N2O)あるいは窒素ガス
(N2)となり大気中に放散される。
2NO2 - + 6H2 → N2 +2H2O+2OH- (3)
2NO3 - +10H2 → N2 +4H2O+2OH- (4)Next, in the denitrification step, the nitrite nitrogen and nitrate nitrogen produced by the above reaction are reduced as described below under anoxic conditions using facultative anaerobic heterotrophic bacteria. Then, it becomes nitric oxide gas (N 2 O) or nitrogen gas (N 2 ) and is emitted into the atmosphere. 2NO 2 - + 6H 2 → N 2 + 2H 2 O + 2OH - (3) 2NO 3 - + 10H 2 → N 2 + 4H 2 O + 2OH - (4)
【0006】通性嫌気性従属栄養細菌は,水素供与体が
必要であり,水素供与体として有機物が通常利用され
る。都市下水などでは,下水中の有機物(BOD成分)
がそのまま用いられ,有機物を含まない廃水ではメタノ
ールなどが外部から添加されることが多い。A facultative anaerobic heterotrophic bacterium requires a hydrogen donor, and an organic substance is usually used as the hydrogen donor. In urban sewage, organic matter (BOD component) in sewage
Is used as is, and in wastewater that does not contain organic substances, methanol etc. are often added from the outside.
【0007】この生物学的硝化脱窒素法は,アンモニア
性窒素濃度が100mg/l以下の廃水では最も安価で
あり,安定した処理方法として広く用いられている。ア
ンモニア性窒素では無く,硝酸性窒素を含む廃水の場合
は先に述べた脱窒反応だけを用いれば良い。This biological nitrification denitrification method is the cheapest for wastewater having an ammoniacal nitrogen concentration of 100 mg / l or less and is widely used as a stable treatment method. In the case of wastewater containing nitrate nitrogen instead of ammonia nitrogen, only the above-mentioned denitrification reaction should be used.
【0008】次にリンの除去に関する従来技術を説明す
る。リンを含む廃水としては化学工場,食品工場廃水,
都市下水などがある。例えば,都市下水中の全リン濃度
は,5〜10mg/l(PO4-Pとして)程度であり,こ
れは屎尿,洗剤,工業薬品などに由来している。リンを
除去する方法としては,鉄やアルミの凝集剤を用いる凝
集沈殿法が最も確実であるが,凝集剤による余剰汚泥量
や薬品費の増大の短所がある。このため,廃水からのリ
ンの除去方法として,生物学的なリン除去方法も広く用
いられるようになった。Next, a conventional technique for removing phosphorus will be described. Wastewater containing phosphorus includes chemical factory, food factory wastewater,
There is urban sewage. For example, the total phosphorus concentration in municipal wastewater is about 5 to 10 mg / l (as PO 4 -P), which is derived from human waste, detergents, industrial chemicals, and the like. The most reliable method for removing phosphorus is the coagulation-sedimentation method using an iron or aluminum coagulant, but it has the disadvantage of increasing the amount of excess sludge and the cost of chemicals due to the coagulant. For this reason, biological phosphorus removal methods have come into wide use as methods for removing phosphorus from wastewater.
【0009】これは,微生物を嫌気性条件下におきリン
を放出させると,好気性条件下ではリンを過剰に摂取し
ようとする性質を利用したもので,都市下水処理の分野
で実用化が進んでいる。このような方式を採用すると下
水の活性汚泥中のリン濃度が2〜3%から5〜6%程度
に増大するといわれている。This is because the microorganisms are placed under anaerobic conditions to release phosphorus, and the property of attempting to ingest phosphorus excessively under aerobic conditions is utilized. Practical application is progressing in the field of municipal wastewater treatment. I'm out. It is said that when such a system is adopted, the phosphorus concentration in the activated sludge of sewage increases from 2 to 3% to 5 to 6%.
【0010】[0010]
【発明が解決しようとする課題】まず,生物学的なリン
の除去方法の課題について説明する。生物学的な脱リン
法は,リン処理の不安定性が課題である。例えば,廃水
中の有機物濃度が低い場合や雨水の希釈効果により,嫌
気槽の酸化還元電位が上昇すると,嫌気槽でのリンの放
出が抑制される。このリンの放出現象が抑制されると,
好気槽でのリンの過剰取り込み能力が低下してしまう。
したがって,嫌気槽の酸化還元電位をいかに安定して下
げておくかが課題となる。これに対して発明者らは,鋭
意検討を進め,嫌気槽の酸化還元電位とリンの過剰取り
込み能力が密接に関係しており,生物処理プロセスの嫌
気槽の酸化還元電位が-270mV(銀/塩化銀電極基準,
以下同じ)超になったら,有機物を多く含む沈砂池越流
水(本発明の最初沈殿池流入水に相当)を嫌気槽に流入
させ,嫌気槽の酸化還元電位を-270mV以下に維持する
方法を提案している(特開平03-278893号公報)。しか
し,この方法のままでは,沈砂池越流水自体の有機物濃
度が小さく,酸化還元電位がすでに-270mV超の場合も
あり,かなりの量の沈砂池越流水を流入させても,実際
には嫌気槽の酸化還元電位がなかなか低下しない場合が
ある。また,大量の沈砂池越流水中を流入させると,反
応槽での有機物負荷の増大や実際の処理時間が短縮され
る影響で,廃水中の有機物や窒素の除去に影響が生じる
課題が残されている。さらに,嫌気槽の酸化還元電位が
低くなりすぎると,無酸素槽での脱窒や好気槽での硝化
に影響する課題も生じてしまうことが明らかになってき
た。これは,汚泥を沈殿池から嫌気槽に返送している
が,嫌気槽であまりにも低い嫌気状態を維持すると,絶
対好気性の硝化細菌が阻害を受け,好気槽での硝化が進
まず,この結果,無酸素槽での脱窒性能が低下するため
と考えられる。したがって,この方法を適用する場合に
おいても,窒素除去への影響を考慮した,より細かな運
転方法の確立が必要である。First, the problems of a biological method for removing phosphorus will be described. Instability of phosphorus treatment is a problem in biological dephosphorization. For example, if the redox potential of the anaerobic tank rises due to a low organic matter concentration in the wastewater or due to the dilution effect of rainwater, the release of phosphorus in the anaerobic tank is suppressed. If this phosphorus release phenomenon is suppressed,
The ability of the aerobic tank to take up phosphorus excessively decreases.
Therefore, how to stably lower the redox potential of the anaerobic tank is an issue. On the other hand, the inventors of the present invention conducted extensive studies and found that the redox potential of the anaerobic tank and the excess uptake capacity of phosphorus are closely related, and the redox potential of the anaerobic tank of the biological treatment process is -270 mV (silver / Silver chloride electrode standard,
The same applies hereafter), a method of keeping the redox potential of the anaerobic tank at -270 mV or less by causing overflow water (corresponding to the first sedimentation tank inflow water of the present invention) overflowing a sand basin containing a large amount of organic matter to flow into the anaerobic tank. Proposed (Japanese Patent Laid-Open No. 03-278893). However, if this method is used as it is, the organic matter concentration of the overflow water of the sedimentation basin itself is small, and the redox potential may already exceed -270 mV. In some cases, the redox potential of the tank does not drop easily. In addition, when a large amount of overflow water from a sand basin is introduced, the organic matter load in the reaction tank increases and the actual treatment time is shortened. ing. Furthermore, it has become clear that if the redox potential of the anaerobic tank becomes too low, problems such as denitrification in the anoxic tank and nitrification in the aerobic tank will occur. This is because sludge is returned from the settling tank to the anaerobic tank, but if the anaerobic tank maintains a too low anaerobic condition, absolutely aerobic nitrifying bacteria are inhibited and nitrification in the aerobic tank does not proceed, As a result, it is considered that the denitrification performance in the anoxic tank decreases. Therefore, even when applying this method, it is necessary to establish a more detailed operation method that considers the effect on nitrogen removal.
【0011】次に,従来の窒素除去方法の課題について
述べる。微生物を用いた廃水中の窒素の処理方法の最大
の課題は,廃水中の有機物や遊離アンモニアの微生物,
特に硝化細菌への阻害である。Next, problems of the conventional nitrogen removing method will be described. The biggest problem in the method of treating nitrogen in wastewater using microorganisms is the microorganism of organic matter and free ammonia in wastewater,
In particular, inhibition of nitrifying bacteria.
【0012】廃水中に含まれる有機物の硝化細菌への阻
害について説明する。硝化細菌は,独立栄養細菌であ
り,阻害を極めて受けやすいため,硝化反応を抑制する
物質は比較的広く調査されている(例えば,生物学的脱
窒素法の歴史的考察,用水と廃水,13,11,p1362〜13
74,1974)。これによると,例えば,コ-クス工場から
発生する廃水などに含まれているフェノ-ルは,わずか
5.6mg/lで,硝化速度がフェノ-ルが無い場合と比較
して75%減少することが報告されている。したがって,
廃水の硝化反応を促進するためには,廃水中の有機物を
硝化反応を促進する前段階で極力除去・削減しておく必
要がある。Inhibition of organic substances contained in wastewater against nitrifying bacteria will be described. Since nitrifying bacteria are autotrophic bacteria and are extremely susceptible to inhibition, substances that suppress the nitrification reaction have been relatively widely investigated (eg, historical consideration of biological denitrification, water and wastewater, 13 , 11, p1362 ~ 13
74, 1974). According to this, for example, the amount of phenol contained in wastewater generated from coke factories is very small.
It has been reported that at 5.6 mg / l, the nitrification rate is reduced by 75% compared to the case without phenol. Therefore,
In order to promote the nitrification reaction of wastewater, it is necessary to remove and reduce organic matter in the wastewater as much as possible before the nitrification reaction is promoted.
【0013】一方で,脱窒素を促進するためには,逆
に,有機物などの水素供与体が必要である。水素供与体
としては有機物のほかに硫黄化合物もある。このような
有機物や硫黄化合物は,脱窒細菌への阻害は小さく,む
しろ,このような廃水中の有機物や硫黄化合物が不足す
れば脱窒素除去性能が低下しやすい。On the other hand, in order to accelerate denitrification, conversely, a hydrogen donor such as an organic substance is required. In addition to organic substances, sulfur compounds are also available as hydrogen donors. Such organic substances and sulfur compounds are less likely to inhibit denitrifying bacteria, but rather, if the organic substances and sulfur compounds in the wastewater are insufficient, the denitrification removal performance is likely to deteriorate.
【0014】このように,生物学的脱窒素法は,廃水が
しばしば硝化細菌に影響がある有機物を含んでいる一方
で,脱窒反応の促進には有機物が必要であることから,
両反応の制御がかなり難しい課題がある。As described above, in the biological denitrification method, since the wastewater often contains organic matter that affects nitrifying bacteria, the organic matter is required to promote the denitrification reaction.
There is a problem that control of both reactions is quite difficult.
【0015】また,廃水中に含まれる遊離のアンモニア
であるが,通常,遊離のアンモニア性窒素濃度が100mg/
lを超えると様々な課題が生じ,安定した処理が困難と
なるといわれている。すなわち,遊離のアンモニア性窒
素濃度が100mg/lを超えると,好気槽の硝化工程におい
て,亜硝酸酸化細菌であるニトロバクターが阻害を受
け,この結果,処理水中の亜硝酸性窒素が蓄積しやす
い。特に,廃水のpHが高くなりすぎると遊離のアンモ
ニアの存在割合が高まるため,硝化阻害が生じやすくな
るといわれている。このような理由から,有機物や遊離
のアンモニア性窒素濃度が高い廃水から,窒素を安定し
て除去することは多くの課題がある。The free ammonia contained in the wastewater usually has a free ammonia nitrogen concentration of 100 mg /
It is said that if it exceeds l, various problems will occur and stable processing will be difficult. That is, when the concentration of free ammonia nitrogen exceeds 100 mg / l, nitrobacter, which is a nitrite-oxidizing bacterium, is inhibited in the nitrification process of the aerobic tank, resulting in the accumulation of nitrite nitrogen in the treated water. Cheap. In particular, it is said that nitrification inhibition is likely to occur when the pH of waste water becomes too high because the proportion of free ammonia present increases. For these reasons, stable removal of nitrogen from organic matter and wastewater having a high concentration of free ammoniacal nitrogen has many problems.
【0016】[0016]
【課題を解決するための手段】本発明者らは,上記の課
題を解決すべく検討を重ねた結果,以下の方法により,
窒素とリンを含有する廃水を安定して効率的に処理する
ことに成功した。本発明の要旨とするところは,次の
(1)〜(12)である。
(1)最初沈殿池,嫌気槽,無酸素槽および好気槽から
なる生物学的プロセスにおいて,最初沈殿池流入水およ
び/または最初沈殿池流出水および/または嫌気槽の酸
化還元電位によって,最初沈殿池流入水と最初沈殿池流
出水を混合し,混合した廃水を嫌気槽,無酸素槽および
好気槽からなる生物学的プロセスに通水して窒素とリン
を除去することを特徴とする廃水からの窒素・リンの除
去方法。
(2)最初沈殿池,嫌気槽,無酸素槽および好気槽から
なる生物学的プロセスにおいて,最初沈殿池流出水およ
び嫌気槽の酸化還元電位が−270mV(銀/塩化銀基
準)以下の場合,最初沈殿池流出水のみを処理すること
を特徴とする廃水からの窒素・リンの除去方法。
(3)最初沈殿池,嫌気槽,無酸素槽および好気槽から
なる生物学的プロセスにおいて,最初沈殿池流入水の酸
化還元電位が−270mV(銀/塩化銀基準)超の場
合,最初沈殿池流入水を混合することなく,最初沈殿池
流出水を嫌気槽に通水し,嫌気槽に最初沈殿池堆積汚泥
および/または硫黄化合物および/または硫黄化合物含
有担体および/またはメタノ―ルおよび/または有機酸
を,嫌気槽の酸化還元電位が−270mVから−400
mV(銀/塩化銀基準)になるように添加することを特
徴とする廃水からの窒素・リンの除去方法。
(4)嫌気槽の酸化還元電位が,−270mVから−4
00mV(銀/塩化銀基準)になるように,ブロア−に
よる曝気および/または最初沈殿池流入水と最初沈殿池
流出水の混合比を調整することを特徴とする請求項1〜
3いずれかに記載の廃水からの窒素・リンの除去方法。
(5)好気槽の処理水を無酸素槽に循環することを特徴
とする請求項1〜4いずれかに記載の廃水からの窒素・
リンの除去方法。
(6)無酸素槽の酸化還元電位が0mVから−200m
V(銀/塩化銀基準)に維持できるように,ブロア−に
よる曝気および/または混合下水および/または硫黄化
合物および/または硫黄化合物含有担体および/または
メタノ―ルおよび/または有機酸の添加量を調整するこ
とを特徴とする請求項1〜5いずれかに記載の廃水から
の窒素・リンの除去方法。
(7)好気槽の酸化還元電位が+100mVから+20
0mV(銀/塩化銀基準)に維持できるように,ブロア
−による曝気量を調整することを特徴とする請求項1〜
6いずれかに記載の廃水からの窒素・リンの除去方法。
(8)嫌気槽および/または無酸素槽および/または好
気槽に微生物固定化担体を投入することを特徴とする請
求項1〜7いずれかに記載の廃水からの窒素・リンの除
去方法。
(9)無酸素槽と好気槽を連続して2段以上用いること
を特徴とする請求項1〜8いずれかに記載の廃水からの
窒素・リンの除去方法。
(10)第2好気槽以降の好気槽の酸化還元電位が+5
0〜+100mV(銀/塩化銀基準)に維持できるよう
に、ブロア−による曝気量を調整することを特徴とする
請求項9に記載の廃水からの窒素・リンの除去方法。Means for Solving the Problems As a result of repeated studies to solve the above problems, the present inventors
We succeeded in treating wastewater containing nitrogen and phosphorus stably and efficiently. The gist of the present invention is the following (1) to (12). (1) In the biological process consisting of the first settling tank, anaerobic tank, anoxic tank and aerobic tank, the first settling tank inflow water and / or the first settling tank outflow water and / or the redox potential of the anaerobic tank It is characterized in that the inflow water of the sedimentation tank and the outflow water of the first sedimentation tank are mixed, and the mixed wastewater is passed through a biological process consisting of an anaerobic tank, anoxic tank and aerobic tank to remove nitrogen and phosphorus. How to remove nitrogen and phosphorus from wastewater. (2) In the biological process consisting of the first settling tank, anaerobic tank, anoxic tank and aerobic tank, when the redox potential of the first settling tank effluent and the anaerobic tank is -270 mV (silver / silver chloride standard) or less , A method for removing nitrogen and phosphorus from wastewater, characterized by treating only the effluent of the first settling tank. (3) In the biological process consisting of the first settling tank, anaerobic tank, anoxic tank and aerobic tank, if the redox potential of the first settling tank inflow water exceeds -270 mV (silver / silver chloride standard), the first settling tank The first settling tank effluent is passed through the anaerobic tank without mixing the pond inflow water, and the first settling tank sediment sludge and / or sulfur compound and / or sulfur compound-containing carrier and / or methanol and / or Alternatively, an organic acid is added to the anaerobic tank at a redox potential of -270 mV to -400
A method for removing nitrogen and phosphorus from wastewater, which is characterized in that it is added so as to be mV (based on silver / silver chloride). (4) The redox potential of the anaerobic tank is -270 mV to -4.
The aeration by a blower and / or the mixing ratio of the first settling tank inflow water and the first settling tank outflow water are adjusted so that it becomes 00 mV (silver / silver chloride standard).
3. The method for removing nitrogen / phosphorus from wastewater according to any one of 3 above. (5) Nitrogen from wastewater according to any one of claims 1 to 4, characterized in that the treated water in the aerobic tank is circulated to the anoxic tank.
How to remove phosphorus. (6) The redox potential of the oxygen-free tank is 0 mV to -200 m.
In order to maintain V (silver / silver chloride standard), aeration with a blower and / or mixed sewage and / or sulfur compound and / or sulfur compound-containing carrier and / or methanol and / or organic acid are added. The method for removing nitrogen / phosphorus from wastewater according to claim 1, wherein the method is adjusted. (7) Redox potential of aerobic tank from +100 mV to +20
The aeration amount by a blower is adjusted so that it can be maintained at 0 mV (based on silver / silver chloride).
6. The method for removing nitrogen / phosphorus from the wastewater according to any one of 6 above. (8) The method for removing nitrogen / phosphorus from wastewater according to any one of claims 1 to 7, wherein the microorganism-immobilized carrier is charged into an anaerobic tank and / or an anoxic tank and / or an aerobic tank. (9) The method for removing nitrogen / phosphorus from wastewater according to any one of claims 1 to 8, wherein an oxygen-free tank and an aerobic tank are continuously used in two or more stages. (10) The redox potential of the aerobic tanks after the second aerobic tank is +5.
The method for removing nitrogen / phosphorus from wastewater according to claim 9, wherein an aeration amount by a blower is adjusted so that the amount of aeration can be maintained at 0 to +100 mV (based on silver / silver chloride).
【0017】(11)最初沈殿池流入水と最初沈殿池流
出水と嫌気槽の酸化還元電位測定装置,および最初沈殿
池流入水と最初沈殿池流出水の混合比の調整用バイパス
配管およびバイパス弁を具備することを特徴とする廃水
からの窒素・リンの除去装置。
(12)嫌気槽および無酸素槽の酸化還元電位調整用ブ
ロア−の送風量調整機能を有する制御装置と混合廃水,
および/または硫黄化合物,および/または硫黄化合物
含有担体,および/またはメタノ―ル,および/または
有機酸の添加量調整機能を有する添加装置を具備するこ
とを特徴とする請求項11に記載の廃水からの窒素・リ
ンの除去装置。(11) First settling basin inflow water, first settling basin outflow and anaerobic oxidation-reduction potential measuring device, and bypass pipe and bypass valve for adjusting mixing ratio of first settling basin inflow and first settling basin outflow A device for removing nitrogen / phosphorus from wastewater, which comprises: (12) A controller and a mixed wastewater having a function of adjusting the air flow rate of a blower for adjusting the redox potential of the anaerobic tank and the anoxic tank.
The wastewater according to claim 11, further comprising an addition device having a function of adjusting the addition amount of the sulfur compound, the sulfur compound, and / or the sulfur compound-containing carrier, and / or the methanol, and / or the organic acid. Device for removing nitrogen and phosphorus from water.
【0018】[0018]
【発明の実施の形態】本発明の処理フロ−例を図1に,
各槽の目標酸化還元電位と機能を表1に,さらに嫌気槽
の酸化還元電位の制御方法を表2に示す。BEST MODE FOR CARRYING OUT THE INVENTION An example of the processing flow of the present invention is shown in FIG.
Table 1 shows the target oxidation-reduction potential and function of each tank, and Table 2 shows the method of controlling the oxidation-reduction potential of the anaerobic tank.
【0019】[0019]
【表1】 [Table 1]
【0020】[0020]
【表2】 [Table 2]
【0021】まず,嫌気槽での運転方法について説明す
る。嫌気槽では,酸化還元電位を低下させ,活性汚泥か
らリンの過剰放出を起こさせる。活性汚泥からリンを過
剰放出させるためには,嫌気槽の酸化還元電位を-270m
V以下にする必要がある。嫌気槽の酸化還元電位を下げ
るために,以下のケースと手段がある。First, the operation method in the anaerobic tank will be described. In the anaerobic tank, the redox potential is lowered, causing excessive release of phosphorus from activated sludge. In order to release phosphorus excessively from activated sludge, the redox potential of the anaerobic tank is set to -270 m.
It must be V or less. The following cases and measures are available to reduce the redox potential of the anaerobic tank.
【0022】表2のCASE1は,最初沈殿池流入水,お
よび,流出水のいずれの酸化還元電位も-270mV超の場
合である。このような場合,最初沈殿池流入水と流出水
を混合して嫌気槽に流入させても,嫌気槽の酸化還元電
位を-270mV以下にすることは困難である。このような
場合,最初沈殿池流出水のみを嫌気槽に通水し,嫌気槽
に最初沈殿池堆積汚泥および/または硫黄化合物および
/または硫黄化合物含有担体および/またはメタノ―ル
および/または有機酸を,嫌気槽の酸化還元電位が-270
mVから-400mVになるように添加することが望ましい。
酸化還元電位が-270mV超では,リンのはきだし量が小
さい。また,酸化還元電位が-400mV未満は,添加した
硫黄やメタノ―ルなどの物質の濃度が高すぎることを意
味しており,硫黄やメタノ―ルが無酸素槽で十分に除去
されず,後段の硝化槽にまで流入するために,硝化細菌
が阻害を受け,硝化反応に悪影響が出る。CASE 1 in Table 2 is the case where the redox potentials of both the first settling tank inflow water and the outflow water are above -270 mV. In such a case, even if the first settling tank inflow water and the outflow water are mixed and allowed to flow into the anaerobic tank, it is difficult to make the oxidation-reduction potential of the anaerobic tank below -270 mV. In such a case, only the effluent of the first settling tank is passed through the anaerobic tank, and the sludge and / or sulfur compound and / or sulfur compound-containing carrier and / or methanol and / or organic acid are accumulated in the first settling tank. , The anaerobic tank redox potential is -270
It is desirable to add it so that it becomes mV to -400 mV.
When the redox potential exceeds -270 mV, the amount of phosphorus extruded is small. If the redox potential is less than -400 mV, it means that the concentration of added substances such as sulfur and methanol is too high, and the sulfur and methanol are not sufficiently removed in the anoxic tank. As it flows into the nitrification tank, the nitrifying bacteria are inhibited and the nitrification reaction is adversely affected.
【0023】表2のCASE2は,最初沈殿池流入水の酸
化還元電位が-270mV以下,および,流出水の酸化還元
電位が-270mV超の場合である。このような場合,最初
沈殿池流入水と最初沈殿池流出水を混合して嫌気槽に流
入させ,嫌気槽の酸化還元電位を-270mV以下にするこ
とが可能である。具体的には,嫌気槽に流入する最初沈
殿池流入水の配管にバイパス弁を具備し,嫌気槽の酸化
還元電位が-270mV以下になるように,バルブの開閉度
を調整する。ただし,-400mV未満になるまで,最初沈
殿池流入水を流入させてはならない。嫌気槽の酸化還元
電位が-400mV未満では,最初沈殿池流入水中の有機物
質の濃度が高すぎることを意味しており,有機物質が無
酸素槽で十分に除去されず,後段の硝化槽にまで流入す
るために,硝化細菌が阻害を受け,硝化反応に悪影響が
出る。CASE2 in Table 2 is the case where the redox potential of the first settling tank inflow water is -270 mV or lower and the redox potential of the outflow water is higher than -270 mV. In such a case, it is possible to mix the first settling tank inflow water and the first settling tank outflow water into the anaerobic tank so that the redox potential of the anaerobic tank is -270 mV or less. Specifically, a bypass valve is installed in the first settling tank inflow water flowing into the anaerobic tank, and the opening / closing degree of the valve is adjusted so that the oxidation-reduction potential of the anaerobic tank is -270 mV or less. However, the first settling tank inflow should not be introduced until the voltage becomes less than -400 mV. If the redox potential of the anaerobic tank is less than -400 mV, it means that the concentration of organic substances in the inflow water of the first settling tank is too high. As it flows in, the nitrifying bacteria are inhibited and the nitrification reaction is adversely affected.
【0024】表2のCASE3は,最初沈殿池流入水,お
よび,流出水の酸化還元電位も-270mV以下の場合であ
る。このような場合,最初沈殿池流出水のみを嫌気槽に
流入させ,嫌気槽の酸化還元電位を-270mV以下にでき
る可能性がある。嫌気槽の酸化還元電位が-270mV以下
になる場合は,最初沈殿池流入水を混合させる必要は無
く,最初沈殿池流出水のみを処理すればよい。CASE 3 in Table 2 is the case where the redox potential of the first settling tank inflow water and the outflow water is also −270 mV or less. In such a case, there is a possibility that only the effluent of the settling basin will first flow into the anaerobic tank and the oxidation-reduction potential of the anaerobic tank can be reduced to -270 mV or less. When the oxidation-reduction potential of the anaerobic tank is -270 mV or less, it is not necessary to mix the first settling tank inflow water, and only the first settling tank outflow water should be treated.
【0025】しかし,最初沈殿池流出水の酸化還元電位
がたとえ-270mV以下であっても,嫌気槽内で有機物分
解が生じるなどして,嫌気槽出口付近の酸化還元電位が
必ずしも-270mV以下に維持されているとは限らない。
嫌気槽の酸化還元電位が-270mV以下にならない場合
は,先にも述べたように,嫌気槽に流入する最初沈殿池
流入水の配管にバイパス弁を具備し,嫌気槽の酸化還元
電位が-270mV以下になるように,バルブの開閉度を調
整すればよい。ただし,-400mV未満になるまで,最初
沈殿池流入水を流入させてはならない。また,最初沈殿
池流出水のみを嫌気槽に流入させた場合でも,嫌気槽の
酸化還元電位が-400mV未満になる可能性がある。嫌気
槽の酸化還元電位が-400mV未満では,先にも述べたよ
うに,残存する有機物により,後段の硝化反応に悪影響
が出るので,-270mVから-400mVになるように,設置し
たブロアーによって,嫌気槽の曝気量を調整することが
望ましい。However, even if the redox potential of the effluent of the first settling tank is -270 mV or less, the redox potential near the outlet of the anaerobic tank is always -270 mV or less due to organic matter decomposition in the anaerobic tank. It is not always maintained.
When the redox potential of the anaerobic tank does not fall below -270 mV, as mentioned above, a bypass valve is installed in the pipe of the first settling tank inflow water that flows into the anaerobic tank, and the redox potential of the anaerobic tank is-. The opening / closing degree of the valve may be adjusted so that it is 270 mV or less. However, the first settling tank inflow should not be introduced until the voltage becomes less than -400 mV. Also, even if only the effluent of the settling tank is first introduced into the anaerobic tank, the redox potential of the anaerobic tank may be less than -400 mV. When the oxidation-reduction potential of the anaerobic tank is less than -400 mV, as described above, the remaining organic matter adversely affects the nitrification reaction in the latter stage. Therefore, by using the blower installed so as to change from -270 mV to -400 mV, It is desirable to adjust the amount of aeration in the anaerobic tank.
【0026】次に第1無酸素槽の運転方法を説明する。
第1無酸素槽では,第1好気槽で硝化細菌によりアンモ
ニア性窒素から生成した亜硝酸性窒素及び硝酸性窒素を
含む処理水を第1無酸素槽に循環ポンプを用いて返送
し,有機物や硫黄化合物を用いて,窒素ガスまで還元す
る。Next, a method of operating the first oxygen-free tank will be described.
In the first anoxic tank, treated water containing nitrite nitrogen and nitrate nitrogen produced from ammonia nitrogen by nitrifying bacteria in the first aerobic tank is returned to the first anoxic tank using a circulation pump, and organic matter is returned. And sulfur compounds are used to reduce to nitrogen gas.
【0027】ここでは,例えば,硫黄成分がある場合,
硫黄酸化細菌によって以下のような反応が進行する。
S2O3 2- + 8/5NO3 - →
4/5N2 + 2SO4 2- + 2/5H+ Here, for example, when there is a sulfur component,
Sulfur-oxidizing bacteria cause the following reactions. S 2 O 3 2- + 8 / 5NO 3 - → 4 / 5N 2 + 2SO 4 2- + 2 / 5H +
【0028】処理する窒素の形態として,硝酸性窒素で
なく,大半が亜硝酸性窒素となっていてもかまわない。
このように硫黄や有機物を利用し,硫黄酸化細菌や従属
栄養細菌によって脱窒反応が進行する。The form of nitrogen to be treated may be nitrite nitrogen instead of nitrate nitrogen.
In this way, by utilizing sulfur and organic substances, the denitrification reaction proceeds by sulfur-oxidizing bacteria and heterotrophic bacteria.
【0029】第1無酸素槽の酸化還元電位は,亜硝酸,
硝酸の還元反応が進行するが,リンの放出が生じない0
〜-200mVが望ましい。第1無酸素槽の酸化還元電位が
0mV超の場合,脱窒反応が低下するため,混合廃水お
よび/または硫黄化合物および/または硫黄化合物含有
担体および/またはメタノ―ルおよび/または有機酸を第
1無酸素槽に添加してもかまわない。一方で,第1無酸素
槽の酸化還元電位が-200mV未満になると,過剰に残留
した硫黄やメタノ―ルによって,後段の硝化反応への悪
影響がでやすいので,設置した酸化還元電位制御用ブロ
アーによる曝気を行い,過剰な硫黄やメタノ―ルを除去
し,酸化還元電位を-200mV以上に維持することが望ま
しい。いずれにせよ,第1無酸素槽の酸化還元電位は,
上記範囲に制御することが好ましい。The redox potential of the first anoxic tank is nitrous acid,
Reduction reaction of nitric acid proceeds, but phosphorus release does not occur 0
~ -200 mV is desirable. When the redox potential of the first anoxic tank exceeds 0 mV, the denitrification reaction decreases, so mixed wastewater and / or sulfur compound and / or sulfur compound-containing carrier and / or methanol and / or organic acid should not be added.
1 May be added to the oxygen-free tank. On the other hand, when the redox potential of the first anoxic tank is less than -200 mV, excessive residual sulfur and methanol are likely to adversely affect the subsequent nitrification reaction. It is desirable to maintain the redox potential at -200 mV or more by removing excess sulfur and methanol by aeration with. In any case, the redox potential of the first anoxic tank is
It is preferable to control within the above range.
【0030】次に第1好気槽の運転方法を説明する。第
1好気槽では,アンモニア酸化細菌により,アンモニア
性窒素を亜硝酸性窒素まで酸化する。続いて,硝酸菌に
より,亜硝酸性窒素を硝酸性窒素まで酸化してもかまわ
ない。
2NH4 + + 3O2 → 2NO2 -+2H2O+4H+
2NO2 - + O2 → 2NO3 - Next, a method of operating the first aerobic tank will be described. In the first aerobic tank, ammonia-oxidizing bacteria oxidize ammoniacal nitrogen to nitrite nitrogen. Subsequently, nitric acid bacteria may oxidize nitrite nitrogen to nitrate nitrogen. 2NH 4 + + 3O 2 → 2NO 2 - + 2H 2 O + 4H + 2NO 2 - + O 2 → 2NO 3 -
【0031】この硝化液を第1無酸素槽に循環させ,脱
窒素反応を促進するのである。硝化反応が順調に進行す
ると,好気槽の酸化還元電位が+100mVから+200mVに
増加する。この値に,酸化還元電位を維持できるよう
に,ブロアーによる曝気量を調整すればよい。酸化還元
電位が+100mV未満では,硝化反応が十分でないこと
が多く,また,+200mV超では硝化反応は十分に進行し
ているので曝気量が無駄となる。This nitrification solution is circulated in the first oxygen-free tank to accelerate the denitrification reaction. When the nitrification reaction proceeds smoothly, the redox potential of the aerobic tank increases from +100 mV to +200 mV. The aeration amount by the blower may be adjusted so that the redox potential can be maintained at this value. If the redox potential is less than +100 mV, the nitrification reaction is often insufficient, and if it exceeds +200 mV, the aeration amount is wasted because the nitrification reaction is sufficiently advanced.
【0032】また,第1好気槽では,細菌によるリンの
過剰取り込みも行われるため,リンが水中から除去され
る。Further, in the first aerobic tank, since phosphorus is taken up by bacteria excessively, phosphorus is removed from water.
【0033】最後に第2無酸素槽,第2好気槽の運転方法
を説明する。単段の無酸素槽-好気槽の場合,循環量を
いくら上げても,原理上,処理水中に亜硝酸性窒素や硝
酸性窒素が残留する。窒素除去率を100%近くに向上さ
せる必要がある場合,以下の第2無酸素槽や第2好気槽
を設置すればよい。すなわち,第2無酸素槽に,第2無
酸素槽の酸化還元電位が0mVから−200mVに維持さ
れるように,混合下水および/または硫黄化合物および
/または硫黄化合物含有担体および/またはメタノ―ル
および/または有機酸を添加すればよい。Finally, a method of operating the second anoxic tank and the second aerobic tank will be described. Single-stage anoxic tank-In the case of an aerobic tank, nitrite nitrogen and nitrate nitrogen remain in the treated water in principle, no matter how much the circulation amount is increased. When it is necessary to improve the nitrogen removal rate to near 100%, the following second anoxic tank or second aerobic tank should be installed. That is, in the second anoxic tank, mixed sewage and / or a sulfur compound and / or a sulfur compound-containing carrier and / or methanol are added so that the redox potential of the second anoxic tank is maintained from 0 mV to -200 mV. And / or an organic acid may be added.
【0034】第2好気槽では,第2無酸素槽出口水中に
残留する有機物やチオ硫酸,硫黄などの還元性硫黄化合
物を,好気性条件下で従属栄養細菌や硫黄酸化細菌によ
り,炭酸ガスや硫酸イオンまで酸化して放流するための
ものである。第2好気槽の酸化還元電位が+50mV未満
では,有機物分解が十分でないことが多く,また,+100
mV超では有機物酸化反応は十分に進行しているので曝
気量が無駄となる。このため,第2好気槽の酸化還元電
位を+50mVから+100mVに維持できるように,ブロア
ーによる曝気量を調整すればよい。第2好気槽の酸化還
元電位は,残存する有機物,硫黄の好気的酸化が主目的
であり,硝化反応を促進させる目的の第1好気槽より
も,酸化還元電位がやや低くてもかまわない。In the second aerobic tank, organic matter and reducing sulfur compounds such as thiosulfuric acid and sulfur remaining in the outlet water of the second anoxic tank are converted into carbon dioxide gas by heterotrophic bacteria and sulfur-oxidizing bacteria under aerobic conditions. It is for oxidizing and releasing sulfate ions. If the redox potential of the second aerobic tank is less than +50 mV, decomposition of organic matter is often insufficient.
Above mV, the amount of aeration is wasted because the organic substance oxidation reaction has proceeded sufficiently. Therefore, the aeration amount by the blower may be adjusted so that the redox potential of the second aerobic tank can be maintained from +50 mV to +100 mV. The redox potential of the second aerobic tank is mainly for aerobic oxidation of residual organic substances and sulfur, and even if the redox potential is slightly lower than that of the first aerobic tank for promoting the nitrification reaction. I don't care.
【0035】廃水の性状変動や水量変動が大きい場合,
処理が不安定になりやすく,無酸素槽と好気槽を上述の
ように連続して2段以上用いることはより望ましいこと
である。3段目以降の無酸素槽と好気槽は,機能的には
第2無酸素槽,第2好気槽と同じであり,酸化還元電位も
2段目と同じでかまわない。When the property variation of the wastewater and the water amount variation are large,
Since the treatment tends to be unstable, it is more desirable to use two or more oxygen-free tanks and aerobic tanks in succession as described above. The anoxic tank and aerobic tank after the third stage are functionally the same as the second anoxic tank and the second aerobic tank, and also have a redox potential.
It is the same as the second stage.
【0036】更に,水温が低下しやすく,脱窒反応や硝
化反応が低下しやすい場合,微生物固定化担体(プラス
チックス,セラミックス,スラグ,ゲル等)を,各槽に
投入し微生物を高濃度化することにより,高効率処理が
可能となる。中でも,ポリプロピレン製の中空円筒状担
体は,微生物が付着しやすく,反応槽内で浮遊しやす
く,また,強度も大きいため,担体として最も望まし
い。各槽への投入量は,担体のみかけ容積で反応槽容量
あたり,5−20%程度である。Further, when the water temperature tends to decrease and the denitrification reaction or nitrification reaction tends to decrease, a microorganism immobilization carrier (plastics, ceramics, slag, gel, etc.) is added to each tank to increase the concentration of microorganisms. By doing so, high efficiency processing becomes possible. Among them, the polypropylene hollow cylindrical carrier is the most preferable as the carrier because microorganisms are easily attached to the carrier and easily float in the reaction tank, and the strength is high. The amount charged into each tank is about 5 to 20% based on the apparent volume of the carrier and the volume of the reaction tank.
【0037】さらに,廃水の窒素の形態がアンモニア性
窒素ではなく,亜硝酸性窒素および/または硝酸性窒素
の場合,後段の第2無酸素槽および第2好気槽は必要な
い。硝化液を循環する必要もない。Further, when the form of nitrogen in the waste water is not ammoniacal nitrogen but nitrite nitrogen and / or nitrate nitrogen, the second anoxic tank and the second aerobic tank in the subsequent stage are not necessary. There is no need to circulate the nitrification solution.
【0038】また,リンを除去する必要がない場合,最
前段の嫌気槽を設ける必要はない。第1無酸素槽(脱
窒)−第1好気槽(硝化促進,循環有)−第2無酸素槽
(有機物,硫黄化合物添加脱窒)−第2好気槽(残留有
機物,硫黄化合物酸化)のプロセスでほぼ100%の窒
素除去が可能となる。When it is not necessary to remove phosphorus, it is not necessary to provide the anaerobic tank at the front stage. First anoxic tank (denitrification) -First aerobic tank (promoting nitrification, with circulation) -Second anoxic tank (organic and sulfur compound added denitrification) -Second aerobic tank (residual organic matter, sulfur compound oxidation) With the process of 1), almost 100% of nitrogen can be removed.
【0039】また,酸化還元電位計は,反応槽が押し出
し流れ,または,押し出し流れに近い場合,反応が終了
している各槽の出口付近に設置することが望ましい。完
全混合の場合は,押し出し流れの場合のように特に限定
しないが,流入水の影響を避けるため,反応槽の中央部
から出口付近に設置することが望ましい。Further, it is desirable that the oxidation-reduction potentiometer is installed near the outlet of each tank where the reaction is completed, when the reaction tank is in the extrusion flow or close to the extrusion flow. In the case of complete mixing, there is no particular limitation as in the case of extrusion flow, but it is desirable to install it from the center of the reaction tank to the vicinity of the outlet in order to avoid the effect of inflow water.
【0040】[0040]
【実施例】以下,本発明の実施例を説明する。EXAMPLES Examples of the present invention will be described below.
【0041】(実施例)都市下水処理への適用
本発明の方法を都市下水処理へ適用し,従来法の改善を
検討した。図1に示すように,最初沈殿池流入水(1)
の浮遊物を最初沈殿池(2)で除去した後,最初沈殿池
流出水(3)を嫌気槽(5),続いて第1無酸素槽
(6),第1好気槽(7)を置き,更に,後段に第2無酸
素槽(8),第2好気槽(9),最終沈殿池(10)を置く
プロセスである。(Example) Application to urban sewage treatment The method of the present invention was applied to urban sewage treatment to study improvement of the conventional method. As shown in Figure 1, first settling tank inflow water (1)
After removing the suspended solids in the first settling tank (2), the first settling tank outflow water (3) is set in the anaerobic tank (5), then in the first anoxic tank (6), and in the first aerobic tank (7). In this process, the second anoxic tank (8), the second aerobic tank (9), and the final settling tank (10) are placed in the subsequent stage.
【0042】最初沈殿池流入水(1)の水質は,BOD
が平均200mg/l,T−N(ト−タル窒素)が平均6
0mg/l(大半が有機性窒素とアンモニア性窒素),
T−P(ト−タルリン)が10mg/l程度である。最初
沈殿池流入水(1)の酸化還元電位(16)は,-200mV
から-400mVと,日間でもかなり変動する。The water quality of the first settling basin inflow water (1) is BOD.
Is an average of 200 mg / l, TN (total nitrogen) is an average of 6
0 mg / l (mostly organic nitrogen and ammonia nitrogen),
TP (total tarrin) is about 10 mg / l. The redox potential (16) of the first settling tank inflow water (1) is -200 mV
From -400 mV, it fluctuates considerably even during the day.
【0043】最初沈殿池流出水(3)の水質は,BOD
が平均100mg/l,T−N(ト−タル窒素)が平均5
0mg/l(大半が有機性窒素とアンモニア性窒素),
T−P(ト−タルリン)が8mg/l程度である。最初
沈殿池流出水(3)の酸化還元電位(17)は,日間で-10
0mVから-200mVとかなり変動するが,-270mV以下
に低下することはほとんどない。The quality of the first settling basin runoff (3) is BOD
Is an average of 100 mg / l, TN (total nitrogen) is an average of 5
0 mg / l (mostly organic nitrogen and ammonia nitrogen),
TP (total tarrin) is about 8 mg / l. The redox potential (17) of the first settling tank runoff (3) was -10
Although it fluctuates considerably from 0 mV to -200 mV, it rarely drops below -270 mV.
【0044】嫌気槽(5)では,リンの放出を促進す
る。最初沈殿池流入水(1)の酸化還元電位(16)が-2
70mV以下の場合,嫌気槽(5)の酸化還元電位(18)
を指標として,バイパス弁(4)の開閉を行い,最初沈
殿池流出水(3)とともに最初沈殿池流入水(1)を嫌
気槽(5)に添加させ,嫌気槽(5)の酸化還元電位(1
8)を-270mV以下に低下させる。また,最初沈殿池流
入水(1)の酸化還元電位(16)が-270mV超の場合,
嫌気槽(5)に流入させても嫌気槽の酸化還元電位(1
8)を低下させることができないので,バイパス弁(4)
を閉じ,最初沈殿池流出水(3)とともに有機物添加装
置(11)からメタノ-ルを嫌気槽(5)に添加させ,嫌
気槽(5)の酸化還元電位(18)を-270mV以下に低下
させる。また,嫌気槽(5)の酸化還元電位(18)が-40
0mVまで低下すれば,一時的にブロア-(12)を稼動さ
せ,嫌気槽(5)の酸化還元電位(18)が-270mVに上
昇すれば停止させる。In the anaerobic tank (5), the release of phosphorus is promoted. First, the redox potential (16) of the inflow water (1) of the sedimentation tank is -2.
If 70 mV or less, redox potential (18) of anaerobic tank (5)
By opening and closing the bypass valve (4) as an index, the first settling tank outflow water (3) and the first settling tank inflow water (1) are added to the anaerobic tank (5), and the redox potential of the anaerobic tank (5) is added. (1
8) is reduced to -270 mV or less. Moreover, when the redox potential (16) of the first settling tank inflow water (1) exceeds -270 mV,
The redox potential of the anaerobic tank (1
8) cannot be lowered, so bypass valve (4)
First, the methanol was added to the anaerobic tank (5) from the organic matter addition device (11) together with the effluent water (3) of the sedimentation tank, and the redox potential (18) of the anaerobic tank (5) was lowered to -270 mV or less. Let Also, the redox potential (18) of the anaerobic tank (5) is -40.
When it decreases to 0 mV, the blower- (12) is temporarily operated, and when the redox potential (18) of the anaerobic tank (5) rises to -270 mV, it stops.
【0045】第1無酸素槽(6)では,第1好気槽(7)
から循環されてくる硝化液中の硝酸性窒素及び亜硝酸性
窒素を,都市下水中のBODで表示される有機物を用いて
除去を行う。硝化液から第1無酸素槽(6)に溶存酸素
が持ち込まれて第1無酸素槽(6)の酸化還元電位(1
9)が上昇しやすいため,有機物添加装置(11)からメ
タノ-ルを第1無酸素槽(6)に添加させ,第1無酸素槽
(6)の酸化還元電位(19)を0mV以下に低下させる。
また,第1無酸素槽(6)の酸化還元電位(19)が-200
mV以下まで低下すれば,一時的にブロア-(12)を稼
動させ,第1無酸素槽(6)の酸化還元電位(19)が0m
Vに上昇すれば停止させる。第1無酸素槽(6)の酸化
還元電位(19)制御用に,最初沈殿池流入水(1)をバ
イパス弁(4)の開閉により供給してもかまわない。In the first anoxic tank (6), the first aerobic tank (7)
Nitrate nitrogen and nitrite nitrogen in the nitrification liquor circulated from the plant are removed by using organic matter represented by BOD in municipal wastewater. Dissolved oxygen is brought into the first anoxic tank (6) from the nitrification solution, and the redox potential (1
9) easily rises, so methanol is added to the first anoxic tank (6) from the organic matter addition device (11), and the redox potential (19) of the first anoxic tank (6) is set to 0 mV or less. Lower.
Also, the redox potential (19) of the first anoxic tank (6) is -200.
If the voltage drops below mV, the blower- (12) is temporarily operated and the redox potential (19) of the first anoxic tank (6) is 0 m.
If it rises to V, stop it. The first settling tank inflow water (1) may be supplied by opening and closing the bypass valve (4) for controlling the redox potential (19) of the first anoxic tank (6).
【0046】第1好気槽(7)は,有機性窒素,アンモ
ニア性窒素の硝酸性窒素までの酸化及び,リンの取り込
みを促進するため,以下の運転条件で第1好気槽を運転
した。すなわち,第1好気槽(7)には,浮遊性の円筒
型プラスチックス担体(内径3mm,長さ4mm)を第1好
気槽容積あたりみかけ容量で15%投入し,硝化細菌を
付着させた。さらに第1好気槽(7)は,ブロア(12)
によって,第1好気槽(7)の酸化還元電位(20)を+1
00mV以上に維持するように運転した。この結果,第1
好気槽(7)において,アンモニア性窒素のほぼ100%が
硝酸性窒素となった。消化液は,循環ポンプ(13)によ
り原水量に対して150%返送した。更に,返送汚泥ポン
プ(14)により,原水量に対して50%,濃縮汚泥(1
5)を返送した。The first aerobic tank (7) was operated under the following operating conditions in order to promote the oxidation of organic nitrogen and ammonia nitrogen to nitrate nitrogen and the uptake of phosphorus. . That is, in the first aerobic tank (7), a floating cylindrical plastics carrier (inner diameter: 3 mm, length: 4 mm) was added at an apparent volume of 15% per first aerobic tank volume to allow nitrifying bacteria to adhere. It was Furthermore, the first aerobic tank (7) is a blower (12).
The redox potential (20) of the first aerobic tank (7) by +1
It was operated so as to maintain it at 00 mV or more. As a result, the first
In the aerobic tank (7), almost 100% of the ammoniacal nitrogen became nitrate nitrogen. The digestive juice was returned by 150% to the amount of raw water by the circulation pump (13). Furthermore, the return sludge pump (14) was used to supply 50% of the amount of raw water to the concentrated sludge (1
5) returned.
【0047】この結果,嫌気槽(5),第1無酸素槽
(6),第1好気槽(7)による処理水中の窒素濃度(す
べて硝酸性窒素)は,年間を通じ5mg/l以下,平均3
mg/lとなり,最初沈殿池流出水の窒素を90%以上,
安定して除去できた。また,処理水のリン濃度も,年間
を通じ1mg/l以下,平均0.5mg/lとなった。As a result, the nitrogen concentration (all nitrate nitrogen) in the treated water in the anaerobic tank (5), the first anoxic tank (6) and the first aerobic tank (7) was 5 mg / l or less throughout the year. Average 3
It becomes mg / l, and the nitrogen of the effluent of the first settling tank is 90% or more,
It could be removed stably. In addition, the phosphorus concentration of treated water was less than 1 mg / l throughout the year, with an average of 0.5 mg / l.
【0048】さらに,窒素の除去率を向上させるため,
第2無酸素槽(8)の酸化還元電位(21)によりバイパ
ス弁(4)を開閉させ,最初沈殿池流入水(1)を第2無
酸素槽(8)に添加させ,第2無酸素槽の酸化還元電位
(21)を0mV以下に低下させる。また,第2無酸素槽
(8)の酸化還元電位(21)が-200mVまで低下すれ
ば,一時的にブロア-(12)を稼動させ,第2無酸素槽
(8)の酸化還元電位(21)が0mVに上昇すれば停止さ
せる。Further, in order to improve the removal rate of nitrogen,
The bypass valve (4) is opened and closed by the redox potential (21) of the second anoxic tank (8), the first settling tank inflow water (1) is added to the second anoxic tank (8), and the second anoxic The redox potential (21) of the tank is lowered to 0 mV or less. Also, if the redox potential (21) of the second anoxic tank (8) drops to -200 mV, the blower- (12) is temporarily operated and the redox potential of the second anoxic tank (8) ( If 21) rises to 0 mV, stop it.
【0049】第2好気槽(9)は,ブロア(12)によっ
て,酸化還元電位を(22)を+50mVから+100mVに
維持するように運転した。The second aerobic tank (9) was operated by the blower (12) so as to maintain the redox potential (22) from +50 mV to +100 mV.
【0050】この結果,総処理時間が18時間の条件
で,処理水(23)中の窒素は平均3mg/l,リンは平
均0.5mg/lとなった。As a result, under the condition that the total treatment time was 18 hours, nitrogen in the treated water (23) was 3 mg / l on average and phosphorus was 0.5 mg / l on average.
【0051】[0051]
【発明の効果】本発明により,窒素及びリンを含有する
廃水から,安定して窒素・リンを除去することが可能と
なる。According to the present invention, it becomes possible to stably remove nitrogen and phosphorus from wastewater containing nitrogen and phosphorus.
【図1】廃水からの脱窒・脱リンプロセスである。FIG. 1 is a denitrification and dephosphorization process from wastewater.
1 最初沈殿池流入水 2 最初沈殿池 3 最初沈殿池流出水 4 バイパス弁 5 嫌気槽 6 第1無酸素槽 7 第1好気槽 8 第2無酸素槽 9 第2好気槽 10 最終沈殿池 11 有機物添加装置 12 ブロア- 13 循環ポンプ 14 返送汚泥ポンプ 15 濃縮汚泥 16〜22 酸化還元電位計 23 処理水 1 First settling tank inflow 2 First settling tank 3 First settling tank runoff 4 Bypass valve 5 Anaerobic tank 6 First anoxic tank 7 First aerobic tank 8 Second anoxic tank 9 Second aerobic tank 10 Final settling tank 11 Organic matter addition device 12 Blower 13 Circulation pump 14 Return sludge pump 15 Concentrated sludge 16-22 Redox potentiometer 23 Treated water
フロントページの続き (72)発明者 伊藤 公夫 富津市新富20−1 新日本製鐵株式会社技 術開発本部内 (72)発明者 朝倉 憲二 東京都千代田区大手町2−6−3 新日本 製鐵株式会社内 (72)発明者 栗田 建紀 東京都千代田区大手町2−6−3 新日本 製鐵株式会社内 Fターム(参考) 4D040 BB12 BB32 BB42 BB57 BB65 BB72 BB82 BB92 BB93 Continued front page (72) Inventor Kimio Ito 20-1 Shintomi, Futtsu City Nippon Steel Co., Ltd. Inside the surgical development headquarters (72) Inventor Kenji Asakura 2-6-3 Otemachi, Chiyoda-ku, Tokyo New Japan Steelmaking Co., Ltd. (72) Inventor Takenori Kurita 2-6-3 Otemachi, Chiyoda-ku, Tokyo New Japan Steelmaking Co., Ltd. F-term (reference) 4D040 BB12 BB32 BB42 BB57 BB65 BB72 BB82 BB92 BB93
Claims (12)
好気槽からなる生物学的プロセスにおいて,最初沈殿池
流入水および/または最初沈殿池流出水および/または
嫌気槽の酸化還元電位によって,最初沈殿池流入水と最
初沈殿池流出水を混合し,混合した廃水を嫌気槽,無酸
素槽および好気槽からなる生物学的プロセスに通水して
窒素とリンを除去することを特徴とする廃水からの窒素
・リンの除去方法。1. In a biological process comprising a first settling tank, an anaerobic tank, an anoxic tank and an aerobic tank, the first settling tank inflow water and / or the first settling tank outflow water and / or the redox potential of the anaerobic tank is used. , Mixing the first settling tank inflow water and the first settling tank outflow water, and passing the mixed wastewater through a biological process consisting of an anaerobic tank, anoxic tank and aerobic tank to remove nitrogen and phosphorus How to remove nitrogen and phosphorus from wastewater.
気槽からなる生物学的プロセスにおいて,最初沈殿池流
出水および嫌気槽の酸化還元電位が−270mV(銀/
塩化銀基準)以下の場合,最初沈殿池流出水のみを処理
することを特徴とする廃水からの窒素・リンの除去方
法。2. In a biological process comprising a first settling tank, an anaerobic tank, an anoxic tank and an aerobic tank, the redox potential of the first settling tank effluent and the anaerobic tank is -270 mV (silver /
A method for removing nitrogen and phosphorus from wastewater, characterized by treating only the effluent of the first settling basin in the following cases.
気槽からなる生物学的プロセスにおいて,最初沈殿池流
入水の酸化還元電位が−270mV(銀/塩化銀基準)
超の場合,最初沈殿池流入水を混合することなく,最初
沈殿池流出水を嫌気槽に通水し,嫌気槽に最初沈殿池堆
積汚泥および/または硫黄化合物および/または硫黄化
合物含有担体および/またはメタノ―ルおよび/または
有機酸を,嫌気槽の酸化還元電位が−270mVから−
400mV(銀/塩化銀基準)になるように添加するこ
とを特徴とする廃水からの窒素・リンの除去方法。3. In the biological process consisting of the first settling tank, anaerobic tank, anoxic tank and aerobic tank, the redox potential of the first settling tank inflow water is -270 mV (based on silver / silver chloride).
If it exceeds, the first settling tank effluent is passed through the anaerobic tank without mixing the first settling tank influent, and the first settling tank sediment sludge and / or sulfur compound and / or sulfur compound containing carrier and / or Or, when methanol and / or organic acid is added, the redox potential of the anaerobic tank is -270 mV.
A method for removing nitrogen / phosphorus from wastewater, which is characterized by adding 400 mV (based on silver / silver chloride).
から−400mV(銀/塩化銀基準)になるように,ブ
ロア−による曝気および/または最初沈殿池流入水と最
初沈殿池流出水の混合比を調整することを特徴とする請
求項1〜3いずれかに記載の廃水からの窒素・リンの除
去方法。4. The redox potential of the anaerobic tank is -270 mV.
4. The aeration by a blower and / or the mixing ratio of the first settling tank inflow water and the first settling tank outflow water are adjusted so as to be −400 mV (silver / silver chloride standard). The method for removing nitrogen and phosphorus from wastewater according to Crab.
とを特徴とする請求項1〜4いずれかに記載の廃水から
の窒素・リンの除去方法。5. The method for removing nitrogen / phosphorus from wastewater according to claim 1, wherein the treated water in the aerobic tank is circulated in the oxygen-free tank.
200mV(銀/塩化銀基準)に維持できるように,ブ
ロア−による曝気および/または混合下水および/また
は硫黄化合物および/または硫黄化合物含有担体および
/またはメタノ―ルおよび/または有機酸の添加量を調
整することを特徴とする請求項1〜5いずれかに記載の
廃水からの窒素・リンの除去方法。6. The redox potential of the anoxic tank is from 0 mV-
Aeration with a blower and / or mixed sewage and / or sulfur compound and / or sulfur compound-containing carrier and / or methanol and / or organic acid is added so as to maintain 200 mV (based on silver / silver chloride). The method for removing nitrogen / phosphorus from wastewater according to claim 1, wherein the method is adjusted.
ら+200mV(銀/塩化銀基準)に維持できるよう
に,ブロア−による曝気量を調整することを特徴とする
請求項1〜6いずれかに記載の廃水からの窒素・リンの
除去方法。7. The aeration amount by a blower is adjusted so that the redox potential of the aerobic tank can be maintained from +100 mV to +200 mV (based on silver / silver chloride). Method for removing nitrogen and phosphorus from wastewater described.
または好気槽に微生物固定化担体を投入することを特徴
とする請求項1〜7いずれかに記載の廃水からの窒素・
リンの除去方法。8. An anaerobic tank and / or an anoxic tank and / or
Alternatively, the nitrogen from wastewater according to any one of claims 1 to 7, wherein the microorganism-immobilized carrier is charged into the aerobic tank.
How to remove phosphorus.
いることを特徴とする請求項1〜8いずれかに記載の廃
水からの窒素・リンの除去方法。9. The method for removing nitrogen / phosphorus from wastewater according to claim 1, wherein the oxygen-free tank and the aerobic tank are continuously used in two or more stages.
位が+50〜+100mV(銀/塩化銀基準)に維持で
きるように、ブロア−による曝気量を調整することを特
徴とする請求項9に記載の廃水からの窒素・リンの除去
方法。10. The aeration amount by a blower is adjusted so that the redox potential of the aerobic tanks after the second aerobic tank can be maintained at +50 to +100 mV (based on silver / silver chloride). Item 9. A method for removing nitrogen and phosphorus from wastewater according to Item 9.
と嫌気槽の酸化還元電位測定装置,および最初沈殿池流
入水と最初沈殿池流出水の混合比の調整用バイパス配管
およびバイパス弁を具備することを特徴とする廃水から
の窒素・リンの除去装置。11. A redox potential measuring device for the first settling tank inflow water, the first settling tank outflow water, and the anaerobic tank, and a bypass pipe and a bypass valve for adjusting the mixing ratio of the first settling tank inflow water and the first settling tank outflow water. A device for removing nitrogen and phosphorus from wastewater, which is characterized by being provided.
調整用ブロア−の送風量調整機能を有する制御装置と混
合廃水,および/または硫黄化合物,および/または硫
黄化合物含有担体,および/またはメタノ―ル,および
/または有機酸の添加量調整機能を有する添加装置を具
備することを特徴とする請求項11に記載の廃水からの
窒素・リンの除去装置。12. A controller having a function of adjusting the air flow rate of a blower for adjusting the redox potential of an anaerobic tank and an anoxic tank, mixed wastewater, and / or a sulfur compound, and / or a carrier containing a sulfur compound, and / or methano. The apparatus for removing nitrogen and phosphorus from wastewater according to claim 11, further comprising: an addition device having a function of adjusting the amount of added organic acid and / or organic acid.
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