JPS6249118B2 - - Google Patents
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- Publication number
- JPS6249118B2 JPS6249118B2 JP55075446A JP7544680A JPS6249118B2 JP S6249118 B2 JPS6249118 B2 JP S6249118B2 JP 55075446 A JP55075446 A JP 55075446A JP 7544680 A JP7544680 A JP 7544680A JP S6249118 B2 JPS6249118 B2 JP S6249118B2
- Authority
- JP
- Japan
- Prior art keywords
- sludge
- tank
- aeration
- activated sludge
- bod
- 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
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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
- Activated Sludge Processes (AREA)
- Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
Description
この発明は活性汚泥による汚水の処理方法、特
に汚泥を再曝気して返送する汚水処理方法に関す
るものである。
従来から、標準活性汚泥法の変法の１つとして
コンタクトスタビリゼイシヨン法が知られてい
る。この方法は、再曝気した活性汚泥を原水と混
合して曝気し、固液分離後、汚泥の一部を再曝気
して返送する方法である。活性汚泥は適当なＦ／
Ｍ比（ここでＦは有機栄養物量、Ｍは活性汚泥微
生物量を示す）に保たれると、凝集、吸着作用と
フロツク形成能が著しく高められるので、この作
用を利用して単時間で汚水を処理し、沈殿池で固
液分離を行うと、良好な処理水が得られる。有機
物を吸着し、沈殿池で濃縮分離された活性汚泥
は、再曝気槽（安定化タンクともいう）で曝気す
ることにより吸着能を回復させ返送する。この活
性汚泥法は、バイオソープシヨン法ともいい、、
有機物を吸着した活性汚泥を濃縮した状態で再曝
気するので、設置面積を少なくできる利点がある
が、送気量が標準活性汚泥法の２倍程度必要であ
り、処理コストが高いという欠点があつた。
この発明はこのような従来法の欠点を改善し、
送気量を少なくしても、効率よく汚水を処理する
ことのできる方法を提供することを目的としてい
る。
この発明は汚水を返送汚泥と混合して嫌気性処
理したのち、曝気処理を行い、固液分離した活性
汚泥の一部を再曝気したのち返送することを特徴
とする汚水処理方法である。
以下図面により説明する。第１図はこの発明の
実施態様を示す系統図であり、１は嫌気槽、２は
曝気槽、３は沈殿槽、４は再曝気槽を示す。
まず原水５を返送汚泥６とともに嫌気槽１に導
入し、緩やかに撹拌して15〜120分間嫌気処理を
行う。ここにおける嫌気処理は完全な嫌気状態を
保つてもよいが、必ずしもその必要性はなくて、
積極的な酸素の供給を行わない程度でよい。この
ため嫌気槽１は密閉状態とする必要はなく、開放
状態で緩やかに撹拌する程度とすることができ
る。
嫌気槽１内の液は一部づつ曝気槽２に導入し、
引き続いて20〜60分間曝気処理を行う。曝気処理
の方法は一般の曝気処理と同様で通気して行う
が、液散式あるいは薄膜式の曝気であつてもよ
い。
曝気槽２内の液は一部づつ取り出して沈殿槽３
に導入し、固液分離を行つて処理水７と活性汚泥
８に分離する。固液分離の手段としては沈殿分離
に限定されず、遠心分離、濾過分離その他の方法
を採用することができる。
分離された活性汚泥８は一部を再曝気槽４に送
つて15〜120分間再曝気し、返送汚泥６として返
送するとともに、残部を余剰汚泥９として系外に
排出する。再曝気の方法は前記曝気処理の方法と
同様である。
一般に活性汚泥は表面が粘着性であるため懸濁
状のBOD（有機栄養物）を体表面に吸着すると
ともに、このように吸着した懸濁性のBODや液
中に存在する溶解性のBODを体内に摂込んで、
この摂込物質を貯蔵物質に変換したり、菌体合成
に利用しており、他は酸化分解してエネルギーを
得ている。従来のコンタクトスタビリゼイシヨン
法では、活性汚泥が液中のBODを吸着したり、
あるいは摂込んでも、貯蔵物質への変換能力が十
分でないので、吸着物質あるいは摂込物質を酸化
分解しないかぎり、新たにBODを摂込むことが
できない。したがつて十分曝気して、吸着物質お
よび摂込物質を消費させる必要があつた。
ところが本発明のように嫌気−好気のサイクル
をくり返えすと、活性汚泥は環境変化に対応でき
る能力を備えるようになり、嫌気状態のときは摂
込物質を酸化分解できないので、貯蔵物質に変換
するようになり、液中のBODを体内に摂込むよ
うになると推定される。
このため嫌気槽１では、返送汚泥は原水中の懸
濁状のBODを吸着するとともに、溶解性のBOD
を体内に摂込んで貯蔵し、そして曝気槽２におい
て曝気処理することにより、残留する懸濁状
BODの吸着性を増すとともに、溶解性BODの摂
込みおよび酸化分解を促進するものと思われる。
こうして原水中のBODは活性汚泥に吸着ないし
摂り込まれるとともに、一部は酸化分解され、沈
殿槽３において分離した処理水のBODは低く保
たれる。また活性汚泥は重質で沈殿性がよく、分
離汚泥は高濃縮状態で排出される。
再曝気槽４では、活性汚泥表面の吸着物質が摂
込まれるとともに、摂込物質の貯蔵物質への変換
および酸化分解が行われるものと思われる。この
場合、吸着物質、摂込物質の完全な酸化分解が行
われるものではないから、除去BODに対する酸
素消費率は従来の場合に比べてはるかに低い。こ
のように再曝気を行うことにより、活性汚泥の
BOD吸着能力および摂込能力は再生され、嫌気
槽１に返送される。
このため、本発明によれば、従来のコンタクト
スタビリゼイシヨン法に比べて、送気量を少なく
しても効率よく汚水を処理することができ、また
汚泥の沈降分離性も良く、高濃度の余剰汚泥を排
出することができる。
なおりん除去を目的として、返送汚泥を原水と
混合して嫌気状態に維持することにより、活性汚
泥からりんを放出させ、その後曝気処理を行うこ
とにより、放出したりんおよび原水中のりんを摂
込ませるようにした活性汚泥法があるが、この方
法では、りんの摂込みのために長時間（1.5時間
以上）曝気処理を行う必要があり、また再曝気は
行われていないので本発明の方法とは区別され
る。このようなりん除去法では活性汚泥を含む混
合液全体を長時間曝気するので大規模の曝気槽と
大量の通気を必要とし、BOD除去の目的のため
には効率が悪い。またそのように長時間曝気処理
を行つた活性汚泥は過剰曝気の状態となつている
から、再曝気による効果の改善はなく、またその
必要もなかつた。これに比べて本発明では混合液
の曝気は短時間でよく、再曝気は分離汚泥のみを
対象とするから、曝気槽は小規模のもので、通気
量も少なくてよい。
次に本発明の実施例について説明する。
実施例
BOD200mg／の下水を第１図のフローで処理
した。その処理条件および結果を表１に示す。表
中SVIは活性汚泥を30分間静置して沈降させたと
き、１ｇの汚泥の占める容積を表し、次式で示さ
れる。
SVI＝ＳＶ／ＭＬＳＳ×104（ml／ｇ）
SV：曝気槽内の混合液を１のメスシリンダに
とり、30分間静置したとき、下部沈殿汚泥の容
積％
MISS：曝気槽内の混合液濃度（mg／）
また除去BODに対する酸素消費率は、曝気槽
および再曝気槽において通気する際の、出入口に
おけるガスおよび液中のCO2濃度変化を測定する
ことにより、
生成ＣＯ２の重量／除去ＢＯＤの重量×100（
％）
を求め、酸素換算した。なおこのときDOは２
mg／以上となるように、曝気槽および再曝気槽
に十分通気した。
比較例 １
嫌気槽を曝気槽に変換して第２図のフロー（同
一符号は第１図と同一部分を示す）で運転したと
ころ、汚泥の沈降性が悪く、沈殿槽による濃縮が
１％程度までであつたので、25％の返送率では系
内のMLSSを高く維持することができず、SS負荷
が高くなつた。処理条件および結果は表１に併記
する。
比較例 ２
比較例１において、前記実施例と同一のSS負
荷とするためには、汚泥返送率を100％に高め、
再曝気槽の滞留時間を長くして運転しなければな
らなかつた。処理条件および結果を表１に併記す
る。
The present invention relates to a method for treating sewage using activated sludge, and particularly to a method for treating sewage by re-aerating and returning sludge. A contact stabilization method has been known as one of the modified methods of the standard activated sludge method. In this method, reaerated activated sludge is mixed with raw water and aerated, and after solid-liquid separation, a portion of the sludge is reaerated and returned. Activated sludge is suitable for F/
When the M ratio (here, F is the amount of organic nutrients and M is the amount of activated sludge microorganisms) is maintained, flocculation, adsorption, and floc formation ability are significantly enhanced. If treated and subjected to solid-liquid separation in a settling tank, good treated water can be obtained. Activated sludge that adsorbs organic matter and is concentrated and separated in a settling tank is aerated in a re-aeration tank (also called a stabilization tank) to recover its adsorption capacity and then sent back. This activated sludge method is also called the biosorption method.
Since the activated sludge that has adsorbed organic matter is re-aerated in a concentrated state, it has the advantage of reducing the installation area, but has the disadvantage that the amount of air supplied is approximately twice that of the standard activated sludge method, and the processing cost is high. Ta. This invention improves the drawbacks of such conventional methods,
The purpose of the present invention is to provide a method that can efficiently treat wastewater even when the amount of air supplied is reduced. This invention is a sewage treatment method characterized by mixing sewage with return sludge, subjecting it to anaerobic treatment, performing aeration treatment, and returning a portion of the solid-liquid separated activated sludge after reaeration. This will be explained below with reference to the drawings. FIG. 1 is a system diagram showing an embodiment of the present invention, in which 1 is an anaerobic tank, 2 is an aeration tank, 3 is a settling tank, and 4 is a reaeration tank. First, the raw water 5 is introduced into the anaerobic tank 1 together with the returned sludge 6, and is gently stirred to perform anaerobic treatment for 15 to 120 minutes. The anaerobic treatment here may maintain a completely anaerobic state, but it is not necessarily necessary.
It is sufficient to not actively supply oxygen. Therefore, the anaerobic tank 1 does not need to be in a closed state, and can be left open and only gently stirred. The liquid in the anaerobic tank 1 is introduced into the aeration tank 2 one by one,
This is followed by aeration for 20-60 minutes. The method of aeration treatment is the same as that of general aeration treatment, and is carried out by aeration, but a droplet type or thin film type aeration may also be used. The liquid in the aeration tank 2 is taken out one by one and transferred to the settling tank 3.
The treated water 7 and activated sludge 8 are separated by solid-liquid separation. The means for solid-liquid separation is not limited to precipitation separation, and other methods such as centrifugation, filtration and separation can be employed. A portion of the separated activated sludge 8 is sent to the re-aeration tank 4 where it is re-aerated for 15 to 120 minutes and returned as return sludge 6, while the remainder is discharged as surplus sludge 9 to the outside of the system. The reaeration method is the same as the aeration treatment method described above. In general, activated sludge has a sticky surface, so it adsorbs suspended BOD (organic nutrients) to the body surface, and also removes suspended BOD that has been adsorbed in this way and soluble BOD that exists in the liquid. Take it into your body,
These ingested substances are converted into storage substances and used for bacterial cell synthesis, and other substances are oxidized and decomposed to obtain energy. In the conventional contact stabilization method, activated sludge adsorbs BOD in the liquid,
Or, even if it is ingested, the ability to convert it into a storage substance is insufficient, so new BOD cannot be ingested unless the adsorbed substance or ingested substance is oxidized and decomposed. Therefore, it was necessary to provide sufficient aeration to consume the adsorbed substances and the incorporated substances. However, when the anaerobic-aerobic cycle is repeated as in the present invention, activated sludge has the ability to respond to environmental changes, and in an anaerobic state, the ingested substances cannot be oxidized and decomposed, so the activated sludge becomes a storage substance. It is presumed that the BOD in the liquid will be ingested into the body. Therefore, in anaerobic tank 1, the returned sludge adsorbs suspended BOD in the raw water, and also absorbs soluble BOD.
By taking it into the body and storing it, and then aerating it in the aeration tank 2, the remaining suspended form is removed.
It seems to increase the adsorption of BOD and promote the uptake and oxidative decomposition of soluble BOD.
In this way, the BOD in the raw water is adsorbed or taken in by the activated sludge, and a portion is oxidized and decomposed, so that the BOD of the treated water separated in the settling tank 3 is kept low. Furthermore, activated sludge is heavy and has good settling properties, and separated sludge is discharged in a highly concentrated state. In the reaeration tank 4, adsorbed substances on the surface of the activated sludge are taken in, and the taken-in substances are presumably converted into storage substances and oxidized and decomposed. In this case, since complete oxidative decomposition of adsorbed substances and entrained substances is not performed, the oxygen consumption rate with respect to removed BOD is much lower than in the conventional case. By performing reaeration in this way, activated sludge
The BOD adsorption capacity and uptake capacity are regenerated and returned to the anaerobic tank 1. Therefore, according to the present invention, compared to the conventional contact stabilization method, sewage can be treated efficiently even with a reduced air flow rate, and the sludge has good sedimentation and separation properties, resulting in high sludge concentration. excess sludge can be discharged. For the purpose of removing phosphorus, the returned sludge is mixed with raw water and maintained in an anaerobic state to release phosphorus from the activated sludge, followed by aeration treatment to incorporate the released phosphorus and the phosphorus in the raw water. There is an activated sludge method in which phosphorus is absorbed, but this method requires aeration treatment for a long time (more than 1.5 hours) to incorporate phosphorus, and re-aeration is not performed. It is distinguished from This phosphorus removal method requires a large-scale aeration tank and a large amount of aeration because the entire mixed solution containing activated sludge is aerated for a long time, which is inefficient for the purpose of BOD removal. In addition, since the activated sludge that had been aerated for such a long time was in a state of excessive aeration, there was no improvement in the effect of re-aeration, nor was there any need for it. In contrast, in the present invention, the aeration of the mixed liquid only takes a short time, and the reaeration is performed only on the separated sludge, so the aeration tank can be small-scale and the amount of aeration can be small. Next, examples of the present invention will be described. Example Sewage with a BOD of 200 mg/was treated according to the flow shown in Figure 1. The processing conditions and results are shown in Table 1. In the table, SVI represents the volume occupied by 1 g of sludge when the activated sludge is left to settle for 30 minutes, and is expressed by the following formula. SVI = SV/MLSS x 10 4 (ml/g) SV: Volume % of bottom settled sludge when the mixed liquid in the aeration tank is placed in a measuring cylinder No. 1 and left to stand for 30 minutes MISS: Concentration of the mixed liquid in the aeration tank (mg/) Oxygen consumption rate relative to removed BOD can be determined by measuring the change in CO 2 concentration in the gas and liquid at the inlet and outlet when aerating in the aeration tank and reaeration tank. weight x 100 (
%) was calculated and converted into oxygen. At this time, DO is 2
The aeration tank and the reaeration tank were sufficiently ventilated so that the amount of water was at least mg/mg/ml. Comparative Example 1 When the anaerobic tank was converted to an aeration tank and operated according to the flow shown in Figure 2 (same symbols indicate the same parts as in Figure 1), the settling of sludge was poor, and the concentration in the settling tank was about 1%. Therefore, with a return rate of 25%, it was not possible to maintain a high MLSS within the system, and the SS load increased. The treatment conditions and results are also listed in Table 1. Comparative Example 2 In Comparative Example 1, in order to achieve the same SS load as in the above example, the sludge return rate was increased to 100%,
The reaeration tank had to be operated with a longer residence time. The treatment conditions and results are also listed in Table 1.
【表】
以上の結果より、本発明の方法では酸素消費率
が小さくて比較例の約60％であり、SVIも小さく
て100を越えないことがわかる。
以上の通り、本発明によれば、
(1) 酸素消費量が小さいため、通気量を少なくす
ることができる。
(2) 活性汚泥中に貯蔵物質を多量につくるので、
汚泥密度が高くなり、沈降性がよい。このため
沈殿槽を小さくして滞留時間を短くすることが
できる。
(3) 処理の主体はBODの酸化分解ではなく、貯
蔵物質への変換であるので、溶解性BODの固
形化であり、そのため沈降性がよく、沈殿槽の
引抜汚泥の濃度は従来法の１％に比べて高く、
２〜３％の高濃度となる。このため系内の
MLSSを高く保持することができ、容積負荷は
高いにもかかわらず汚泥負荷を低くすることが
できるとともに、余剰汚泥の処理を容易にする
ことができる。
などの効果がある。[Table] From the above results, it can be seen that in the method of the present invention, the oxygen consumption rate is small, about 60% of that of the comparative example, and the SVI is also small, not exceeding 100. As described above, according to the present invention: (1) Since the amount of oxygen consumed is small, the amount of ventilation can be reduced. (2) Since a large amount of storage material is created in activated sludge,
The sludge density is high and the settling property is good. Therefore, the settling tank can be made smaller and the residence time can be shortened. (3) The main body of the treatment is not oxidative decomposition of BOD, but the conversion into storage materials, so the soluble BOD is solidified, and therefore has good settling properties, and the concentration of the sludge drawn from the settling tank is lower than that of the conventional method. higher than %;
The concentration is as high as 2-3%. Therefore, within the system
It is possible to maintain a high MLSS, reduce the sludge load despite the high volumetric load, and facilitate the treatment of excess sludge. There are effects such as
第１図はこの発明の実施態様を示す系統図、第
２図は比較例の処理方法を示す系統図である。
各図中、同一符号は同一部分を示すものとし、
１は嫌気槽、２は曝気槽、３は沈殿槽、４は再曝
気槽である。
FIG. 1 is a system diagram showing an embodiment of the present invention, and FIG. 2 is a system diagram showing a processing method of a comparative example. In each figure, the same symbols indicate the same parts,
1 is an anaerobic tank, 2 is an aeration tank, 3 is a settling tank, and 4 is a reaeration tank.
Claims (1)
ち、曝気処理を行い、固液分離した活性汚泥の一
部を再曝気したのち返送することを特徴とする汚
水処理方法。 ２ 嫌気性処理を15〜120分間行うものである特
許請求の範囲第１項記載の汚水処理方法。 ３ 曝気処理は20〜60分間行うものである特許請
求の範囲第１項または第２項記載の汚水処理方
法。 ４ 再曝気は15〜120分間行うものである特許請
求の範囲第１項ないし第３項のいずれかに記載の
汚水処理方法。[Scope of Claims] 1 A sewage treatment method characterized by mixing sewage with returned sludge, subjecting it to anaerobic treatment, performing aeration treatment, re-aerating a portion of the solid-liquid separated activated sludge, and then returning it. . 2. The wastewater treatment method according to claim 1, wherein the anaerobic treatment is performed for 15 to 120 minutes. 3. The sewage treatment method according to claim 1 or 2, wherein the aeration treatment is performed for 20 to 60 minutes. 4. The sewage treatment method according to any one of claims 1 to 3, wherein the reaeration is performed for 15 to 120 minutes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7544680A JPS571491A (en) | 1980-06-06 | 1980-06-06 | Disposal of sewage |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7544680A JPS571491A (en) | 1980-06-06 | 1980-06-06 | Disposal of sewage |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS571491A JPS571491A (en) | 1982-01-06 |
| JPS6249118B2 true JPS6249118B2 (en) | 1987-10-16 |
Family
ID=13576484
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7544680A Granted JPS571491A (en) | 1980-06-06 | 1980-06-06 | Disposal of sewage |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS571491A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006088014A (en) * | 2004-09-22 | 2006-04-06 | Kurita Water Ind Ltd | Treatment method for organic waste water |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5898194A (en) * | 1981-12-07 | 1983-06-10 | Nishihara Environ Sanit Res Corp | Purification of filthy water |
| JPS5952590A (en) * | 1982-09-18 | 1984-03-27 | Ukai Nobuyoshi | Biological treatment of waste water containing organic substance |
| JPS5952592A (en) * | 1982-09-18 | 1984-03-27 | Ukai Nobuyoshi | Biological treatment of waste water containing organic substance |
| JP4892917B2 (en) * | 2005-10-12 | 2012-03-07 | 栗田工業株式会社 | Biological treatment method and apparatus for organic wastewater |
| JP2007275847A (en) * | 2006-04-11 | 2007-10-25 | Sumitomo Heavy Industries Environment Co Ltd | Wastewater treating apparatus and wastewater treating method |
| JP4880509B2 (en) * | 2007-03-26 | 2012-02-22 | 住重環境エンジニアリング株式会社 | Wastewater treatment equipment |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4056465A (en) * | 1976-04-12 | 1977-11-01 | Air Products And Chemicals, Inc. | Production of non-bulking activated sludge |
| JPS5518558A (en) * | 1978-07-27 | 1980-02-08 | Kagaku Gijutsu Shinkoukai | Recovering method for copper from ferric chloride etching waste solution containing copper |
-
1980
- 1980-06-06 JP JP7544680A patent/JPS571491A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006088014A (en) * | 2004-09-22 | 2006-04-06 | Kurita Water Ind Ltd | Treatment method for organic waste water |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS571491A (en) | 1982-01-06 |
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