JPS6231639B2 - - Google Patents
Info
- Publication number
- JPS6231639B2 JPS6231639B2 JP10183979A JP10183979A JPS6231639B2 JP S6231639 B2 JPS6231639 B2 JP S6231639B2 JP 10183979 A JP10183979 A JP 10183979A JP 10183979 A JP10183979 A JP 10183979A JP S6231639 B2 JPS6231639 B2 JP S6231639B2
- Authority
- JP
- Japan
- Prior art keywords
- denitrification
- amount
- denitrifying
- bacteria
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 claims description 66
- 241000894006 Bacteria Species 0.000 claims description 57
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 23
- 229910052799 carbon Inorganic materials 0.000 claims description 23
- 230000012010 growth Effects 0.000 claims description 16
- 230000007423 decrease Effects 0.000 claims description 15
- 239000002351 wastewater Substances 0.000 claims description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 66
- 230000001580 bacterial effect Effects 0.000 description 24
- 238000002347 injection Methods 0.000 description 14
- 239000007924 injection Substances 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 10
- 239000000758 substrate Substances 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 3
- 244000005700 microbiome Species 0.000 description 3
- 230000001546 nitrifying effect Effects 0.000 description 3
- 230000029058 respiratory gaseous exchange Effects 0.000 description 3
- 208000035404 Autolysis Diseases 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 206010057248 Cell death Diseases 0.000 description 2
- 230000029087 digestion Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000000813 microbial effect Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 230000028043 self proteolysis Effects 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 230000010261 cell growth Effects 0.000 description 1
- 230000006727 cell loss Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000010800 human waste Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 230000035755 proliferation Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Landscapes
- Biological Treatment Of Waste Water (AREA)
- Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
Description
【発明の詳細な説明】
本発明は、下水、し尿、その他産業廃液などの
廃水を脱窒工程の媒体上に付着した脱窒素菌を利
用して効果的に脱窒する生物学的脱窒法に関する
ものである。
一般に生物学的脱窒法は活性汚泥法と、粒状、
塊状、板状、網状、棒状、繊維状、管状の媒体に
微生物を付着して利用する生物固定床法に大別さ
れるが、設置面積に制限のある処理施設では、硝
化菌、脱窒素菌を純粋かつ高濃度に維持でき、装
置の縮小が可能な固定床法が実用化されている。
この従来の固定床法の脱窒処理は通常廃水中の窒
素（以下Ｎとする）化合物、例えばNH4を硝化工
程でNO2あるいはNO3（以下NOxとする）に硝化
したのち、脱窒素菌が付着した媒体によつて固定
層あるいは流動層の形成されている脱窒工程で
NOxをN2ガスにまで還元分解（脱窒）するもの
である。この方法で発生する余剰菌の処理は、媒
体を再利用するため、媒体を脱窒工程より引抜い
た後媒体に付着した菌体と媒体とを分離し、媒体
は脱窒工程に返送し、一方菌体は脱水、乾燥、焼
却されるが、この方法は媒体に対する菌体の付着
が強力なため剥離に大きなエネルギーを必要とす
るし、また剥離された菌体は純粋培養化されてい
るので極めて脱水性が悪い等の欠点がある。
また嫌気的消化法を利用して、媒体上の菌体を
可溶化し、媒体より分離する方法もあるが、これ
も菌体の可溶化に長時間を要するうえ、消化脱離
液の再処理が必要であるという欠点を有する。こ
のような従来の余剰菌の処理法はいずれも操作が
煩雑であるうえ前記の如き欠点があり当業界にと
つて憂慮されている問題であつた。とりわけ余剰
脱窒素菌の処理法の改良が大きな問題となつてい
るが、これは、利用する硝化菌の増殖量が0.1増
殖菌量／NH4−Ｎ（ｇ／ｇ）であるのに対し、脱
窒素菌の増殖量は、菌体収率の小さいメタノール
資化性脱窒素菌でも0.4増殖菌量／NO3−Ｎ
（ｇ／ｇ）と、除去窒素あたり硝化菌の４倍量に
も達するためである。
本発明は、これら従来法の諸欠点を除去しよう
とするもので、生物学的脱窒法において、媒体上
の脱窒素菌の量を制御することで菌体を脱窒工程
から引抜くことも、菌体を媒体より分離すること
もなく極めて容易で経済的な余剰脱窒素菌の処理
処分を可能にする廃水の生物学的脱窒法を提供す
ることを目的とするものである。
本発明は、メタノールによる脱窒反応（外呼吸
型脱窒反応）で媒体上に増殖した脱窒素菌をメタ
ノールを減少、即ち脱窒素菌の構成成分自体を還
元剤とする脱窒反応（内呼吸型脱窒反応）によつ
て媒体上に増殖した余剰脱窒素菌を減少せしめた
のち再びメタノールによる脱窒反応で脱窒素菌を
増殖するという方法を複数の脱窒工程を利用し、
工程全体の脱窒素菌量が一定量保持されるように
して処理する生物学的脱窒法である。
次に本発明の実施態様について図面を参照して
説明すると、NH3を含有する廃水１は全部又はそ
の一部が硝化工程２でNO3に硝化され、NO3のみ
を含有する硝化水３は直接、メタノール１４なし
で脱窒工程４に流入し、NO3の大部分は脱窒さ
れ、残部はバルブ１０，８を経由してメタノール
１４とともに脱窒工程５に流入し脱窒が完了した
のちバルブ１３を経由して放流される。
この場合、前記廃水１はその一部又は全部がバ
イパス流路１′で直接前記脱窒工程４，５に流入
して処理することができる。
一方脱窒工程４では菌体成分自体を還元剤とす
る内呼吸型脱窒により菌体は次第に減少し、脱窒
工程５ではメタノールによる脱窒反応で菌体は増
加する。内呼吸型の脱窒速度はメタノールによる
脱窒反応のおおよそ１／５〜１／10である。従つ
て、脱窒工程４，５の菌体量が同じであれば、脱
窒工程４に流入するNOxの10〜20％を除去し、
脱窒工程５では残留する80〜90％のNOxを除去
すれば効率的な脱窒処理をすることができる。次
に、この脱窒工程４，５の脱窒素菌がそれぞれ過
剰に減少、増加する前に、硝化水３の注入は脱窒
工程５に、メタノール１４の注入は脱窒工程４に
切り換えられる。
前記脱窒工程５において、硝化水３中のNOx
−Ｎの一部はメタノール１４無注入で脱窒され、
残留するNOx−Ｎはバルブ１１，７を経由し、
脱窒工程４にメタノール１４とともに流入し、脱
窒を完了したのち、バルブ１２を経由して放流さ
れる。以後同様の操作で脱窒工程４，５に硝化水
３、メタノール１４を交互に繰返し注入すること
によつて工程全体の脱窒素菌を定量的に保持する
ことができる。
なお、前記脱窒工程の菌体量および脱窒量の調
節はメタノールの注入量を増減することによつて
行うことができる。即ち、増殖した菌体の減少
は、必ずしもメタノール１４を完全に停止せずと
も、菌体の増殖に不足な量にまで注入量を低下す
ればよく、この場合、メタノール無注入より脱窒
速度は大きくなり、菌体の減少量は少なくなる。
脱窒工程の菌体量の制御は、例えば、脱窒工程
４，５の総菌体量が増加傾向にある場合はメタノ
ール注入工程のメタノール量を減少し、総菌体量
が減少傾向にある場合にはメタノール注入工程の
メタノール量を増加すればよいが、脱窒工程をそ
れぞれ複数工程設けることによつて融通性が付加
され、負荷変動に対しても安定した脱窒処理と菌
体の定量保持をすることができる。また硝化水と
メタノールの注入を工程から工程へ切換える時期
は、メタノール注入工程の媒体に付着した脱窒素
菌の肥大あるいは肥大による媒体からの剥離の状
態を観察することによつて決定することができ
る。またメタノール無注入工程の脱窒素菌が内呼
吸型脱窒反応によつてほとんど減少してしまえば
媒体の脱窒機能が損なわれるので、そうなる以前
を切り換えの時期としてもよい。脱窒機能の低下
は、媒体上の脱窒素菌量を観察すれば大体推定で
きるが、処理水質の分析によつて確実に知ること
ができる。このように肉眼あるいは分析などの手
動操作による切換えによつて切換え時期を経験的
に把握できれば、タイマで切換え時間を設定する
ことによつて切換えの自動化もできる。また媒体
が粒状媒体であれば、脱窒素菌の増減によつて媒
体層の高さが増減するので、それを観察して切換
えてもよいが、層高（固液界面）の増減を光の透
過率あるいは他の手段による界面計を用いて検知
することによつて切換えの自動化をすることがで
きる。
例えば有機炭素源の過不足を判断する肉眼によ
る観察の際に脱窒素菌の増殖に不十分な有機炭素
源の注入量の見分け方としては媒体に付着してい
る脱窒素菌の量をみて、経験的に判断する。十分
な量の場合には菌量も増え生物膜も成長する。逆
に不十分な量にすると生物膜は収縮したように小
さくなり、流出水と一緒に流れ出るのを見分けれ
ばよい。例えば、小規模の廃水を処理する場合に
は脱窒工程に透明あるいは半透明なプラスチツク
構造物を用いるので、外側から増殖量を観察する
ことができるし、また鋼板等の不透明な材料によ
る構造体を用いる場合には砂ろ過塔等に配備され
ているような覗き窓を脱窒塔の側面に縦長に取り
付けることによつて、塔内の脱窒菌の増殖量を観
察することができる。
以上のような方法によつて塔内脱窒菌量を観察
しながら、試行錯誤的に脱窒菌の増殖に不十分な
有機炭素源の注入量を決定することができる。す
なわち、脱窒菌量が次第に減少していくように有
機炭素源量の注入量を減少していくか、あるいは
注入を停止すればよい。
特に増殖に不足な量とは、有機炭素源を添加し
て菌が増殖すれば、十分な量であり、菌が増殖し
なければ不足な量となるのであるが経時的変化を
みて判断する。即ちある時の菌の状態を基にし
て、次の時に菌がどうなつているかで判断する。
すなわち、次の時に前より菌が増えて生物膜が成
長していれば十分な量であり、菌が減少（収縮）
して生物膜が不安定な状態であれば、不足量であ
ると判断すればよい。また具体的には脱窒素菌の
増殖に不足な有機炭素源の量について脱窒菌も含
めた微生物一般の増殖量は次式で求めることがで
きる。
△Xs＝α・Ls−β・Xs ……(1)
△Xs：菌体の増殖量 （Kg／日）
Xs：反応槽（脱窒工程）の菌体量（Kg）
Ls：基質（有機炭素源）の流入量（Kg／
日）
α：基質の菌体転換率（収率）（−）
β：菌体の自己消化率 （ ／日）
注） 内生呼吸脱窒は菌体の自己消化によつて
行われる。
第(1)式に示されているように流入する基質の量
が少ない場合には△Xsは負となる。例えば、
α，βをそれぞれ通常使用されている0.4，0.05
に設定し、Ls，Xsをそれぞれ0.02Kg／日、1.0Kg
とすると、第(1)式より△Xsは−0.042Kg／日、す
なわち一日に0.042Kgの菌体が減少する。また基
質の注入量が０の場合には、△Xs＝0.05Kg／日
と計算される。
このように有機炭素源を注入しても脱窒工程に
保持されている脱窒菌の量が減少傾向にある状態
を有機炭素源が不足であると判断すればよい。
なお前記各脱窒工程における菌体量および脱窒
素量の調節は、メタノール注入工程、無注入工程
の配分とメタノール注入量の増減とを同時にある
いはそれぞれ単独に調整、制御することによつて
行うことができる。
さらに有機炭素源の注入量はそれぞれの脱窒素
菌体の増殖に十分な量および零乃至脱窒素菌の増
殖に不足な量に交互に繰返えし処理する場合少な
くとも別の脱窒工程でそれぞれ行なうのがよく、
前記有機炭素源は脱窒工程の脱窒素菌が減少した
時点で注入され、増加した時点で中止乃至注入減
量を行なうようにすることが考慮されている。
さらにまた前記脱窒工程４と脱窒工程５との複
数工程は並列又は直列に連結され必要に応じ両者
を選択的に切換えられる形態の脱窒工程に連結す
るシステムにするのが便利である。
本発明によれば、硝化水を一方の脱窒工程Ａに
流入せしめて該脱窒工程Ａで有機炭素源注入量を
零乃至脱窒素菌の増殖に不足な量にして硝化水中
のNOx−Ｎの一部を除去し、残留NOx−Ｎを他
方の脱窒工程Ｂにおいて有機炭素源を注入して除
去する方法と、硝化水を脱窒工程Ｂに流入せしめ
て該脱窒工程Ｂで有機炭素源注入量を零乃至脱窒
素菌の増殖に不足な量にして硝化水中のNOx−
Ｎの一部を除去し、残留NOx−Ｎを脱窒工程Ａ
において有機炭素源を注入して除去する方法とを
交互に切換えて繰り返すことにより、余剰菌体の
処理設備が不要となるほか脱窒処理水の浄化効率
が著しく向上され処理操作も余剰菌体の処理がバ
ルブなどの操作だけですみ極めて簡単であつて運
転管理も容易で余剰菌の処理と同時に脱窒処理水
の浄化も行なうことができるので余剰脱窒素菌の
処理処分に付随する従来の欠点を解消し、大幅に
改良化された脱窒処理とすることができ余剰菌の
処理費用が不要となり、また硝化水の流入に対し
て後段に位置する脱窒工程では有機炭素源を添加
しているので、微生物からNH3が溶出することが
なく、高率の窒素除去率を達成することができる
し、さらに内呼吸型脱窒によりメタノールも節減
され、処理コストも大巾に節減できるなどの従来
の脱窒素菌の処理処分に付随する欠点を解消し、
大幅に改良化された脱窒処理とすることができ
る。
次に本発明の実施例について示す。
実験装置
流動層式脱窒塔 50円筒カラム ２本
（φ200mm、高さ1600mm、有効容積50.2）
実験条件
実験廃水 人工硝化液NO3−Ｎ 30mg／
（脱塩素水道水にNaNO3を添
加して調整したもの）
廃水処理量 2000／日
流動層媒体 砂
流動層菌量は流動層層高をもつて増減をみた
実験開始時の流動層層高
第１塔 1400mm（脱窒工程Ａ）
第２塔 600mm（脱窒工程Ｂ）
実験開始時の流動層菌体濃度は
21000mg／であつた。
【表】DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a biological denitrification method for effectively denitrifying wastewater such as sewage, human waste, and other industrial wastewater by using denitrifying bacteria attached to a denitrifying process medium. It is something. In general, biological denitrification methods include activated sludge method, granular,
It is broadly divided into biological fixed bed methods, which use microorganisms attached to lump-like, plate-like, net-like, rod-like, fibrous, and tubular media, but in treatment facilities with limited installation space, nitrifying bacteria, denitrifying bacteria A fixed bed method has been put into practical use that can maintain purity and high concentration of carbon dioxide and reduce the size of the equipment.
In this conventional fixed bed denitrification treatment, nitrogen (hereinafter referred to as N) compounds in wastewater, such as NH 4 , are nitrified into NO 2 or NO 3 (hereinafter referred to as NOx) in the nitrification process, and then denitrifying bacteria In the denitrification process, a fixed bed or a fluidized bed is formed by the adhering medium.
It reduces and decomposes NOx to N2 gas (denitrification). In order to reuse the medium in this method, the medium is removed from the denitrification process, the bacteria attached to the medium are separated from the medium, and the medium is returned to the denitrification process. The bacterial cells are dehydrated, dried, and incinerated, but this method requires a large amount of energy to detach because the bacterial cells adhere strongly to the medium, and since the detached bacterial cells are pure cultures, it is extremely difficult to use. It has drawbacks such as poor dehydration properties. There is also a method that uses anaerobic digestion to solubilize the bacterial cells on the medium and separate them from the medium, but this also requires a long time to solubilize the bacterial cells, and the digestion fluid is reprocessed. It has the disadvantage that it requires All of these conventional methods for treating surplus bacteria are complicated in operation and have the above-mentioned drawbacks, which are problems that are of concern to the industry. In particular, improving the treatment method for surplus denitrifying bacteria has become a major issue, but this is because the growth rate of the nitrifying bacteria used is 0.1 growth rate/NH 4 -N (g/g). The growth rate of denitrifying bacteria is 0.4 bacterial growth/NO 3 −N even for methanol-assimilating denitrifying bacteria with a small bacterial cell yield.
(g/g), which is four times the amount of nitrifying bacteria per nitrogen removed. The present invention aims to eliminate the various drawbacks of these conventional methods.In the biological denitrification method, by controlling the amount of denitrifying bacteria on the medium, it is possible to withdraw the bacterial cells from the denitrifying process. The object of the present invention is to provide a biological denitrification method for wastewater that enables extremely easy and economical treatment and disposal of surplus denitrifying bacteria without separating the bacterial cells from the medium. The present invention reduces methanol from denitrifying bacteria grown on a medium through a denitrification reaction using methanol (external respiration type denitrification reaction). Using multiple denitrification processes, the excess denitrifying bacteria that have grown on the medium are reduced by a denitrifying reaction (type denitrifying reaction), and then the denitrifying bacteria are grown again by a denitrifying reaction using methanol.
This is a biological denitrification method that maintains a constant amount of denitrifying bacteria throughout the process. Next, an embodiment of the present invention will be described with reference to the drawings. The wastewater 1 containing NH 3 is all or partially nitrified to NO 3 in the nitrification step 2, and the nitrified water 3 containing only NO 3 is Directly flows into denitrification step 4 without methanol 14, most of the NO 3 is denitrified, and the remainder flows into denitrification step 5 together with methanol 14 via valves 10 and 8, after denitrification is completed. It is discharged via valve 13. In this case, a part or all of the wastewater 1 can directly flow into the denitrification processes 4 and 5 through the bypass channel 1' and be treated. On the other hand, in the denitrification step 4, the number of bacterial cells gradually decreases due to endorespiration type denitrification using the bacterial component itself as a reducing agent, and in the denitrification step 5, the number of bacterial cells increases due to the denitrification reaction using methanol. The denitrification rate of the endorespiration type is approximately 1/5 to 1/10 of the denitrification reaction using methanol. Therefore, if the amounts of bacterial cells in denitrification steps 4 and 5 are the same, 10 to 20% of the NOx flowing into denitrification step 4 will be removed,
In denitrification step 5, efficient denitrification can be achieved by removing 80 to 90% of the remaining NOx. Next, before the denitrification bacteria in denitrification steps 4 and 5 excessively decrease and increase, respectively, the injection of nitrified water 3 is switched to denitrification step 5, and the injection of methanol 14 is switched to denitrification step 4. In the denitrification step 5, NOx in the nitrified water 3
- Some of the N is denitrified without injection of methanol 14,
The remaining NOx-N passes through valves 11 and 7,
It flows into the denitrification process 4 together with methanol 14, and after completing denitrification, is discharged via the valve 12. Thereafter, by repeating the same operation and alternately injecting nitrified water 3 and methanol 14 into the denitrification steps 4 and 5, the denitrification bacteria in the entire process can be quantitatively maintained. Note that the amount of bacterial cells and the amount of denitrification in the denitrification step can be adjusted by increasing or decreasing the amount of methanol injected. In other words, to reduce the number of proliferated microbial cells, it is not necessary to completely stop the methanol 14, but it is sufficient to reduce the amount of injection to an amount insufficient for the proliferation of the microbial cells. The size of the bacteria increases, and the amount of bacterial cell loss decreases.
To control the amount of bacterial cells in the denitrification step, for example, if the total amount of bacterial cells in denitrification steps 4 and 5 tends to increase, reduce the amount of methanol in the methanol injection step, so that the total amount of bacterial cells tends to decrease. In some cases, the amount of methanol in the methanol injection process can be increased, but by providing multiple denitrification processes, flexibility is added, and stable denitrification and bacterial cell quantification can be achieved even with load fluctuations. can be retained. In addition, the timing to switch the injection of nitrification water and methanol from one process to another can be determined by observing the enlargement of denitrifying bacteria attached to the medium during the methanol injection process or their separation from the medium due to enlargement. . Furthermore, if the denitrifying bacteria in the methanol-free process are almost completely reduced by the endorespiratory denitrification reaction, the denitrifying function of the medium will be impaired, so the changeover may be made before this happens. The decline in denitrification function can be roughly estimated by observing the amount of denitrifying bacteria on the medium, but it can be determined with certainty by analyzing the quality of treated water. If the switching timing can be determined empirically by the naked eye or by manual operation such as analysis, the switching can be automated by setting the switching time with a timer. Furthermore, if the medium is a granular medium, the height of the medium layer will increase or decrease depending on the increase or decrease of denitrifying bacteria, so you can observe this and change the layer height, but you can change the height of the layer (solid-liquid interface) by using light. Switching can be automated by sensing using interfacial measurement by transmittance or other means. For example, during visual observation to determine excess or deficiency of organic carbon sources, one way to determine whether the amount of organic carbon source to be injected is insufficient for the growth of denitrifying bacteria is to look at the amount of denitrifying bacteria attached to the medium. Judge empirically. If the amount is sufficient, the amount of bacteria will increase and a biofilm will grow. On the other hand, if the amount is insufficient, the biofilm will shrink and become smaller, and all you have to do is to notice that it flows out with the runoff water. For example, when treating small-scale wastewater, transparent or semi-transparent plastic structures are used in the denitrification process, so the amount of growth can be observed from the outside, and structures made of opaque materials such as steel plates are used. When using a denitrification tower, the amount of growth of denitrification bacteria in the tower can be observed by attaching a viewing window, such as that installed in a sand filter tower, vertically to the side of the denitrification tower. By the method described above, while observing the amount of denitrifying bacteria in the column, it is possible to determine by trial and error the amount of organic carbon source to be injected that is insufficient for the growth of denitrifying bacteria. That is, the amount of organic carbon source injected may be reduced so that the amount of denitrifying bacteria gradually decreases, or the injection may be stopped. In particular, the amount insufficient for growth is an amount that is sufficient if the bacteria grow by adding an organic carbon source, and an insufficient amount if the bacteria do not grow, and is determined by looking at changes over time. In other words, based on the state of the bacteria at one time, judgments are made based on the state of the bacteria at the next time.
In other words, if the next time there are more bacteria than before and the biofilm is growing, it is sufficient, and the bacteria will decrease (shrink).
If the biofilm is unstable, it can be determined that the amount is insufficient. More specifically, regarding the amount of organic carbon source insufficient for the growth of denitrifying bacteria, the growth amount of microorganisms in general, including denitrifying bacteria, can be determined by the following formula. △Xs = α・Ls−β・Xs ...(1) △Xs: Amount of bacterial cell growth (Kg/day) Xs: Amount of bacterial cells in the reaction tank (denitrification process) (Kg) Ls: Substrate (organic carbon source) inflow amount (Kg/
(day) α: Substrate conversion rate (yield) (-) β: Autolysis rate of bacteria (/day) Note: Endogenous respiration denitrification is performed by autolysis of bacteria. As shown in equation (1), when the amount of substrate flowing in is small, ΔXs becomes negative. for example,
α and β are the commonly used 0.4 and 0.05, respectively.
, and Ls and Xs are 0.02Kg/day and 1.0Kg, respectively.
Then, from equation (1), ΔXs is -0.042Kg/day, that is, the number of bacterial cells decreases by 0.042Kg per day. Furthermore, when the amount of substrate injected is 0, ΔXs is calculated as 0.05 Kg/day. A state in which the amount of denitrifying bacteria retained in the denitrification process tends to decrease even if the organic carbon source is injected in this manner may be determined to be a lack of the organic carbon source. The amount of bacterial cells and the amount of denitrification in each of the denitrification steps can be adjusted by adjusting and controlling the distribution of the methanol injection step and non-injection step and the increase/decrease of the methanol injection amount simultaneously or individually. I can do it. Furthermore, if the amount of organic carbon source injected is alternately repeated between an amount sufficient for the growth of each denitrifying bacteria and an amount insufficient for the growth of the denitrifying bacteria, the amount of injection of the organic carbon source may be repeated at least in different denitrification steps. It is good to do
It is considered that the organic carbon source is injected when the number of denitrifying bacteria in the denitrification process decreases, and when the number of denitrifying bacteria increases, the amount of the organic carbon source is stopped or the amount of injection is reduced. Furthermore, it is convenient to form a system in which the denitrification process 4 and the denitrification process 5 are connected in parallel or in series, and the denitrification process is connected to the denitrification process in such a manner that the denitrification process can be selectively switched as necessary. According to the present invention, nitrified water is caused to flow into one of the denitrification processes A, and in the denitrification process A, the amount of organic carbon source injected is reduced to zero or an amount insufficient for the growth of denitrification bacteria to reduce NOx-N in the nitrification water. The remaining NOx-N is removed by injecting an organic carbon source in the other denitrification process B, and the organic carbon source is removed in the denitrification process B by flowing nitrified water into the denitrification process B. NOx− in the nitrified water is
Part of the N is removed and the remaining NOx-N is denitrified in process A.
By alternately switching and repeating the method of injecting an organic carbon source and removing it, there is no need for equipment to treat excess bacteria, and the purification efficiency of denitrified water is significantly improved. The treatment is extremely simple, requiring only the operation of valves, etc., and operation management is also easy. It is possible to purify the denitrifying treated water at the same time as treating surplus bacteria, which is a disadvantage of conventional methods of treating and disposing of surplus denitrifying bacteria. This eliminates the problem and enables a significantly improved denitrification process, eliminating the need for processing costs for excess bacteria.Also, an organic carbon source can be added in the denitrification process that is located after the inflow of nitrified water. As a result, NH 3 does not elute from microorganisms, making it possible to achieve a high nitrogen removal rate.Furthermore, internal respiration type denitrification saves methanol and significantly reduces processing costs. Eliminates the drawbacks associated with conventional treatment and disposal of denitrifying bacteria,
A significantly improved denitrification process can be achieved. Next, examples of the present invention will be described. Experimental equipment Fluidized bed denitrification tower 2 50 cylindrical columns (φ200mm, height 1600mm, effective volume 50.2) Experimental conditions Experimental wastewater Artificial nitrification solution NO 3 -N 30mg/ (adjusted by adding NaNO 3 to dechlorinated tap water) Wastewater treatment amount 2000/day Fluidized bed medium Sand The amount of bacteria in the fluidized bed varied with the height of the fluidized bed Fluidized bed height at the start of the experiment 1st tower 1400mm (Denitrification process A) 2nd tower 600mm (Denitrification process B) The fluidized bed bacterial cell concentration at the start of the experiment was 21000 mg/. 【table】
図面は本発明方法のフローシートである。
１…廃水、２…硝化工程、３…硝化水、４，５
…脱窒工程、６，７，８，９，１０，１１，１
２，１３…バルブ、１４…有機炭素源、１５，１
６…バルブ。
The drawing is a flow sheet of the method of the present invention. 1...Wastewater, 2...Nitrification process, 3...Nitrified water, 4,5
...Denitrification process, 6, 7, 8, 9, 10, 11, 1
2,13...Bulb, 14...Organic carbon source, 15,1
6...Valve.
Claims (1)
素（NOx−Ｎ）を除去するに際し、脱窒工程を
少なくとも二工程に分離し、硝化水を一方の脱窒
工程Ａに流入せしめて該脱窒工程Ａで有機炭素源
注入量を零乃至脱窒素菌の増殖に不足な量にして
硝化水中のNOx−Ｎの一部を除去し、残留NOx
−Ｎを他方の脱窒工程Ｂにおいて有機炭素源を注
入して除去し脱窒素水を得る通水方法と、硝化水
を脱窒工程Ｂに流入せしめて該脱窒工程Ｂで有機
炭素源注入量を零乃至脱窒素菌の増殖に不足な量
にして硝化水中のNOx−Ｎの一部を除去し、残
留NOx−Ｎを脱窒工程Ａにおいて有機炭素源を
注入して除去し脱窒素水を得る通水方法とを交互
に切換えて硝化水を通水することを特徴とする廃
水の生物学的脱窒法。 ２ 前記両方法がその切換えを一定時間毎に行わ
れるようにタイマで設定されて処理するものであ
る特許請求の範囲第１項記載の廃水の脱窒法。 ３ 前記脱窒工程が、粒状媒体で行われるもので
あつて、脱窒素菌の増減によつて生ずる媒体の層
高の増減を検知して切換えられて処理されるもの
である特許請求の範囲第１項又は第２項記載の廃
水の脱窒法。[Claims] 1. When removing oxidized nitrogen (NOx-N) using denitrifying bacteria attached to a medium, the denitrifying process is separated into at least two steps, and nitrified water is used in one denitrifying process. In the denitrification step A, the amount of organic carbon source injected is reduced to zero or an amount insufficient for the growth of denitrification bacteria, and a portion of the NOx-N in the nitrified water is removed, and residual NOx is
-N is removed by injecting an organic carbon source in the other denitrification process B to obtain denitrified water, and nitrified water is made to flow into the denitrification process B and an organic carbon source is injected in the denitrification process B. Part of the NOx-N in the nitrified water is removed by reducing the amount to zero or an amount insufficient for the growth of denitrifying bacteria, and the residual NOx-N is removed by injecting an organic carbon source in the denitrification process A to produce denitrified water. A biological denitrification method for wastewater, which is characterized in that nitrified water is passed through the water by alternating with the water passing method to obtain the nitrified water. 2. The method for denitrifying wastewater according to claim 1, wherein both of the methods are set with a timer so that the switching is performed at regular intervals. 3. The denitrification process is carried out in a granular medium, and the process is switched by detecting an increase or decrease in the layer height of the medium caused by an increase or decrease in the number of denitrifying bacteria. The method for denitrifying wastewater according to item 1 or 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10183979A JPS5626595A (en) | 1979-08-10 | 1979-08-10 | Biological denitrifying method for waste water |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10183979A JPS5626595A (en) | 1979-08-10 | 1979-08-10 | Biological denitrifying method for waste water |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5626595A JPS5626595A (en) | 1981-03-14 |
| JPS6231639B2 true JPS6231639B2 (en) | 1987-07-09 |
Family
ID=14311230
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10183979A Granted JPS5626595A (en) | 1979-08-10 | 1979-08-10 | Biological denitrifying method for waste water |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5626595A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63187659U (en) * | 1987-05-27 | 1988-12-01 |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6479507B2 (en) * | 2015-03-06 | 2019-03-06 | 株式会社東芝 | Organic wastewater treatment equipment |
-
1979
- 1979-08-10 JP JP10183979A patent/JPS5626595A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63187659U (en) * | 1987-05-27 | 1988-12-01 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5626595A (en) | 1981-03-14 |
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