JP3447037B2 - Aerobic digestion of activated sludge - Google Patents
Aerobic digestion of activated sludgeInfo
- Publication number
- JP3447037B2 JP3447037B2 JP34374196A JP34374196A JP3447037B2 JP 3447037 B2 JP3447037 B2 JP 3447037B2 JP 34374196 A JP34374196 A JP 34374196A JP 34374196 A JP34374196 A JP 34374196A JP 3447037 B2 JP3447037 B2 JP 3447037B2
- Authority
- JP
- Japan
- Prior art keywords
- sludge
- aerobic digestion
- ozone
- activated sludge
- tank
- 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 - Fee Related
Links
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
- Y02W10/20—Sludge processing
Landscapes
- Treatment Of Sludge (AREA)
Description
【発明の詳細な説明】
【0001】
【発明の属する技術分野】本発明は、有機性汚水の活性
汚泥処理施設から排出される余剰活性汚泥を大幅に減量
化する方法に関する。
【0002】
【従来の技術】下水の活性汚泥処理施設など、有機性汚
水の活性汚泥処理施設から大量の余剰活性汚泥が発生し
ており、これらの余剰活性汚泥の処理処分が現在最大の
問題になっている。従来、余剰活性汚泥は難脱水性であ
るため、多量の脱水助剤(ポリマなど)を添加し脱水機
で脱水した後焼却処分しているが、汚泥が大量な場合、
脱水助剤コストが高く、脱水機、焼却炉が大規模なもの
になり設備費、維持管理費が多大になっている。なお、
従来より前記余剰活性汚泥を生物学的に減量する汚泥減
量化法として嫌気性消化法、好気性消化法があるが、1
0日間以上という長時間の滞留時間を必要とする割りに
は減量化率が劣るため、最近はほとんど採用されない。
また図2のように、活性汚泥に直接オゾンを添加し汚泥
を可溶化したのち好気性消化する方法(特公昭57−1
9719)も提案されているが、この方法を有機性汚水
の生物処理施設からの余剰活性汚泥の減量化に適用する
のは所要オゾン添加量が多くなり、オゾンコストが高額
につくため実用性が乏しい。
【0003】また余剰活性汚泥に直接オゾンを添加して
汚泥を可溶化する前記技術には次の問題点もある。すな
わち、余剰活性汚泥に直接オゾンを添加して汚泥を一部
可溶化した後好気性消化槽に送って好気性消化すると、
供給活性汚泥には可溶化されない汚泥がかなり存在
し、この可溶化されない汚泥を好気性消化するのが極め
て困難である。
一部可溶化して生成したBODを含む供給生物汚泥
から新たな汚泥が多量に生成する。この新たに生成した
汚泥にはオゾンが添加されないので、これら汚泥の好気
性消化は進行しにくい。
【0004】
【発明が解決しようとする課題】本発明は、活性汚泥に
直接オゾンを添加して好気性消化する前記処理法を見直
し、低コストで活性汚泥を好気性消化する際に発生する
余剰活性処理汚泥を完全に減量化できる新技術を提供す
ることが課題である。そのことによって汚泥脱水機、焼
却炉を不要にし汚泥処理工程を合理化することを課題と
する。
【0005】
【課題を解決するための手段】本発明は好気性消化とオ
ゾン酸化による汚泥の可溶化を新規な態様で結合させ、
活性汚泥を好気性消化しながらオゾン酸化し汚泥の効果
的減量化を実現する。すなわち、本発明の好気性消化方
法は、有機性汚水の活性汚泥処理施設から排出される余
剰活性汚泥を、好気性消化した後固液分離し、該固液分
離で分離された分離汚泥の大部分を前記好気性消化工程
に返送すると共に、該分離汚泥の一部にオゾンを添加し
て処理し、前記分離汚泥の大部分と共に前記好気性消化
工程に供給することを特徴とする活性汚泥の好気性消化
方法である。なお、以下には有機性汚水の活性汚泥処理
施設から発生する汚泥は活性汚泥、その活性汚泥を好気
性消化した汚泥は「生物処理汚泥」という。
【0006】既に前記したように、活性汚泥に直接オゾ
ンを添加して化学的にオゾン酸化処理して可溶化する場
合は、多量のオゾンが必要となるが、本発明の態様では
活性汚泥を好気性消化して生物処理汚泥とし、前記好気
性微生物に分解され易い生物処理汚泥にオゾンを添加し
てオゾン酸化して可溶化して減量化するので、減量化が
容易に進行する。また、生物処理汚泥の一部にオゾンを
添加し、可溶化した場合、可溶化汚泥中に残留するオゾ
ンは少ないので、これを好気性消化工程に還流した時好
気性消化の微生物に及ぼす残留オゾンの影響が少ない。
【0007】また好気性消化工程では、適当な一定範囲
の汚泥濃度に維持することが消化処理を効率的なものに
するが、この所定の濃度に維持するためには消化汚泥の
一部を好気性消化工程から抜き出すことが望ましい。本
発明においては、好気性消化工程から系外に抜き出した
一部の汚泥にオゾンを添加して化学酸化により汚泥を可
溶化し、可溶化汚泥を好気性消化工程に返送することに
より余剰汚泥を減量化すると共に、好気性消化工程内の
汚泥濃度もまた適当な一定範囲の汚泥濃度に維持するこ
とが可能である。
【0008】生物処理汚泥を効果的に可溶化するための
オゾンの適性添加量は、生物処理汚泥固形物に対しおお
よそ10〜20%である。本発明では、好気性消化工程
から系外に抜き出した一部の生物処理汚泥にオゾンを添
加してオゾン酸化するので、生物汚泥を直接化学的にオ
ゾン酸化処理して可溶化する場合に比較し、オゾンの使
用量を大幅に少なくできるので、オゾンコストも大幅に
低減することができる。生物処理汚泥にオゾンを添加し
て化学酸化により可溶化した汚泥(可溶化汚泥)は、そ
の後、可溶化汚泥をさらに好気性微生物の存在下で曝気
処理する好気性消化工程に供給し、可溶化汚泥を好気性
微生物により炭酸ガスと水に分解する。
【0009】本発明の別の態様として、生物処理汚泥に
オゾンを添加してオゾン酸化し、可溶化した可溶化汚泥
をさらに好気性消化する好気性消化工程としては、先工
程の好気性消化工程に直接還流するのではなく、別の下
水などの汚水の活性汚泥法などの好気性消化工程が行わ
れる生物処理工程を利用し、或いはそれを間に介在させ
るようにしても構わない。本発明において、好気性消化
工程における固液分離する手段としては、(i) 沈澱池に
貯蔵し、沈降性汚泥は沈降させて固液分離する方法や(i
i)分離膜を装填したろ過器により固液分離する方法等を
挙げることができる。
【0010】
【発明の実施の形態】本発明の有機性汚泥の減量化方法
の1例を以下に図1により説明する。下水などの有機性
汚水の活性汚泥処理施設から排出される余剰活性汚泥1
を好気性消化槽2に供給し、酸素含有ガス(空気など)
で曝気し好気性消化する。好気性消化によって活性汚泥
は自己消化を起こし、汚泥の一部(30%程度)が炭酸
ガス、水に分解される。しかし大部分(70%程度)の
汚泥は、長時間曝気しても自己消化が進みにくく減量化
が進まない。好気性消化槽2からその生物処理汚泥を固
液分離槽3へ送る。本発明では好気性消化槽2に後続す
る固液分離槽3(例えば沈澱槽)から沈澱した分離汚泥
4を引き抜き、その大部分は返送汚泥5として好気性消
化槽2に返送し、その一部の汚泥は移送汚泥6としてオ
ゾン酸化槽7に移送し、オゾン酸化槽7において汚泥に
オゾン8を添加し、酸化反応によって汚泥を可溶化し、
可溶化汚泥9は前記返送汚泥5と共に好気性消化槽2に
返送する。
【0011】本発明の方法においては、好気性消化によ
って消化されて得た生物処理汚泥の一部を分岐し、その
分岐した汚泥にオゾンを添加して可溶化し、可溶化汚泥
を好気性消化槽2に返送するようにした結果、汚泥の自
己消化がきわめて効果的に進むことが認められた。この
理由はオゾンの酸化作用によって、汚泥の自己消化の進
行を妨げている多糖類、強固な微生物細胞壁が破壊され
やすくなり自己消化が進みやすくなるためではないかと
考えられる。
【0012】本発明により活性汚泥は、ほぼ完全に減量
化され、図1のプロセスから系外にほとんど汚泥が発生
しなくなる。従って汚泥脱水機、汚泥焼却炉などが不要
になるか又は大幅に小さい規模で済む。本発明における
好気性消化槽の水理学的滞留時間は7日程度で良く、従
来の好気性消化法の所要滞留日数の1/2程度に縮小さ
れる。本発明におけるオゾンの適正添加量は、分岐した
生物処理汚泥の固形物1kgあたり3〜5%と少ない量
で十分である。本発明は好気性消化しながら少量のオゾ
ンを添加し消化の阻害要因を減少させる方法を適用した
ため、前述した図2に示した公知技術(供給活性汚泥に
多量のオゾンを添加し汚泥を十分可溶化したのち好気性
消化する方法)に比べオゾン添加量が少なくて済む。
【0013】また本発明による活性汚泥の減量化方法に
おいて、好気性消化槽で消化された生物処理汚泥を膜分
離手段により固液分離した場合、興味深い効果が認めら
れた。すなわち、膜分離おいて膜汚染が少なくなること
が認められた。そのため従来公知の余剰汚泥処理工程で
は沈澱法により固液分離する必要があるのに対し、本発
明ではより効率的な膜分離手段により固液分離しても分
離膜をほとんど交換する必要がないので十分使用できる
という利点が認められた。
【0014】
【実施例】図1の工程に基づく実験条件を第1表に示
す。下水の余剰活性汚泥(固形物濃度5.0g/リット
ル)を前記図1に示した処理フローに従って処理した。
汚泥処理量は10リットル/日(50g/日)である。
好気性消化工程で使用する好気性消化槽2の容積は70
リットルであり、消化槽2を空気で曝気し、槽内被処理
液中の溶存酸素量は5〜6mg/リットルに維持し、消
化槽1内の温度は25℃で、汚泥濃度は5〜6g/リッ
トルである。前記の好気性消化により生成した生物処理
汚泥は沈澱法により固液分離し、そこで分離された分離
水は系外に排出し、分離汚泥4の大部分は返送汚泥5と
して好気性消化槽2に返送する。分離汚泥の一部は、移
送汚泥6として下記第1表に示す仕様のオゾン酸化槽7
に導入し、そこで前記汚泥にオゾン8を添加し、酸化反
応によって汚泥を可溶化し、可溶化汚泥9は前記返送汚
泥5と共に好気性消化槽2に返送する。
【0015】
【表1】
【0016】この条件で9カ月試験を続けた結果、供給
した余剰活性汚泥総重量(9kg)の96%が分解さ
れ、系外への汚泥排出量は微量であった。
【0017】
【発明の効果】
1.余剰活性汚泥の減量効果が著しく大きく、汚泥処理
処分工程が合理化される。系外への汚泥排出量を微量と
することができる。
2.活性汚泥に対して使用するオゾン量が著しく減少す
るために、オゾン添加コストが削減される。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for significantly reducing excess activated sludge discharged from an activated sludge treatment facility for organic wastewater. 2. Description of the Related Art A large amount of excess activated sludge is generated from an activated sludge treatment facility for organic sewage such as a sewage activated sludge treatment facility, and the treatment and disposal of such excess activated sludge is currently the biggest problem. Has become. Conventionally, excess activated sludge is difficult to dewater, so a large amount of dehydration aid (polymer, etc.) is added, dewatered by a dehydrator, and then incinerated.
Dehydration aid costs are high, and dehydrators and incinerators are large-scale, and equipment costs and maintenance costs are high. In addition,
Conventionally, there are anaerobic digestion and aerobic digestion as sludge reduction methods for biologically reducing the excess activated sludge.
It is hardly used recently because the weight reduction rate is inferior to the one requiring a long residence time of 0 day or more.
Also, as shown in FIG. 2, a method of directly adding ozone to activated sludge to solubilize the sludge and then aerobically digesting it (Japanese Patent Publication No. 577-1)
9719), but applying this method to the reduction of excess activated sludge from biological treatment facilities for organic sewage requires a large amount of added ozone and increases the cost of ozone. poor. [0003] The above-mentioned technique of directly adding ozone to surplus activated sludge to solubilize sludge also has the following problems. In other words, when ozone is directly added to the excess activated sludge to partially solubilize the sludge and then sent to the aerobic digestion tank to perform aerobic digestion, there is considerable sludge that is not solubilized in the supplied activated sludge and is not solubilized. Aerobic digestion of sludge is extremely difficult. A large amount of new sludge is produced from the supplied biological sludge containing BOD produced by partially solubilizing. Since ozone is not added to this newly generated sludge, aerobic digestion of these sludges does not easily proceed. SUMMARY OF THE INVENTION The present invention is directed to a process for aerobic digestion of activated sludge by directly adding ozone to the activated sludge, and the surplus generated when aerobic digestion of activated sludge is performed at low cost. The challenge is to provide a new technology that can completely reduce the amount of activated sludge. It is an object of the present invention to eliminate the need for a sludge dehydrator and an incinerator and to streamline the sludge treatment process. SUMMARY OF THE INVENTION The present invention combines aerobic digestion and solubilization of sludge by ozone oxidation in a novel manner,
Ozone oxidation while aerobic digestion of activated sludge realizes effective sludge reduction. That is, in the aerobic digestion method of the present invention, the excess activated sludge discharged from the activated sludge treatment facility of the organic wastewater is subjected to aerobic digestion and then to solid-liquid separation, and a large amount of the separated sludge separated by the solid-liquid separation is obtained. Returning the part to the aerobic digestion step, treating the sludge by adding ozone to a part of the separated sludge, and supplying the separated sludge to the aerobic digestion step together with most of the separated sludge. It is an aerobic digestion method. Hereinafter, the sludge generated from the activated sludge treatment facility of the organic wastewater is referred to as activated sludge, and the sludge obtained by aerobically digesting the activated sludge is referred to as “biologically treated sludge”. As described above, when ozone is directly added to activated sludge to chemically solubilize it by ozone oxidation, a large amount of ozone is required. In the embodiment of the present invention, activated sludge is preferably used. Ozone is added to the biologically treated sludge which is easily digested by the aerobic microorganisms by digestion into a biologically treated sludge, and ozone is oxidized and solubilized to reduce the amount thereof. In addition, when ozone is added to a part of the biologically treated sludge and solubilized, the amount of ozone remaining in the solubilized sludge is small. Is less affected. In the aerobic digestion process, maintaining the sludge concentration in a suitable and constant range makes the digestion treatment efficient, but in order to maintain the predetermined concentration, a part of the digested sludge is preferably used. It is desirable to withdraw from the temper digestion process. In the present invention, ozone is added to a part of the sludge extracted from the system from the aerobic digestion step to solubilize the sludge by chemical oxidation, and the excess sludge is returned by returning the solubilized sludge to the aerobic digestion step. Along with the reduction, the sludge concentration in the aerobic digestion process can also be maintained at an appropriate range of sludge concentration. [0008] The appropriate addition amount of ozone for effectively solubilizing the biotreated sludge is approximately 10 to 20% based on the biotreated sludge solids. In the present invention, ozone is added to a part of the biologically treated sludge extracted from the aerobic digestion process to the outside of the system, and the ozone is oxidized, so that the biological sludge is directly chemically ozone-oxidized and solubilized. Since the amount of ozone used can be significantly reduced, the cost of ozone can also be significantly reduced. The sludge solubilized by chemical oxidation by adding ozone to the biologically treated sludge (solubilized sludge) is then supplied to an aerobic digestion process in which the solubilized sludge is further aerated in the presence of aerobic microorganisms, and solubilized. Decompose sludge into carbon dioxide and water by aerobic microorganisms. In another embodiment of the present invention, the aerobic digestion step of adding ozone to the biologically treated sludge, oxidizing it with ozone, and further aerobic digesting the solubilized solubilized sludge includes the aerobic digestion step of the preceding step. Instead of directly refluxing the wastewater, a biological treatment step in which an aerobic digestion step such as an activated sludge method for wastewater such as another sewage is performed may be used or may be interposed therebetween. In the present invention, as means for solid-liquid separation in the aerobic digestion step, (i) a method of storing in a sedimentation basin, and sedimentation of the settling sludge and solid-liquid separation by (i)
i) A method of performing solid-liquid separation using a filter equipped with a separation membrane, and the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One example of the method for reducing organic sludge of the present invention will be described below with reference to FIG. Surplus activated sludge 1 discharged from activated sludge treatment facility of organic wastewater such as sewage
Is supplied to the aerobic digestion tank 2 and oxygen-containing gas (air, etc.)
Aerobically digested with aerosol. Activated sludge self-digests by aerobic digestion, and a part (about 30%) of sludge is decomposed into carbon dioxide and water. However, most of the sludge (about 70%) is hardly self-digested even if it is aerated for a long time, and weight loss does not progress. The biologically treated sludge is sent from the aerobic digestion tank 2 to the solid-liquid separation tank 3. In the present invention, the precipitated separated sludge 4 is withdrawn from a solid-liquid separation tank 3 (for example, a settling tank) subsequent to the aerobic digestion tank 2, and most of the separated sludge is returned to the aerobic digestion tank 2 as returned sludge 5, and a part of the sludge is returned Is transferred to the ozone oxidation tank 7 as the transfer sludge 6, and the ozone 8 is added to the sludge in the ozone oxidation tank 7 to solubilize the sludge by an oxidation reaction.
The solubilized sludge 9 is returned to the aerobic digestion tank 2 together with the return sludge 5. In the method of the present invention, a part of the biologically treated sludge obtained by digestion by aerobic digestion is branched, and the branched sludge is solubilized by adding ozone, and the solubilized sludge is subjected to aerobic digestion. As a result of returning to the tank 2, it was recognized that the self-digestion of the sludge proceeded extremely effectively. It is considered that the reason for this is that the oxidizing action of ozone easily breaks down polysaccharides and strong microbial cell walls that hinder the progress of autolysis of sludge, and facilitates autolysis. According to the present invention, activated sludge is reduced almost completely, and almost no sludge is generated outside the system from the process of FIG. Therefore, a sludge dewatering machine, a sludge incinerator and the like are not required, or the size thereof can be significantly reduced. The hydraulic retention time of the aerobic digestion tank in the present invention may be about 7 days, which is reduced to about の of the number of days required for the conventional aerobic digestion method. In the present invention, an appropriate amount of ozone to be added is as small as 3 to 5% per kg of solid matter of the branched biological treatment sludge. Since the present invention employs a method of adding a small amount of ozone while aerobic digestion to reduce the factors inhibiting digestion, the above-mentioned known technique shown in FIG. (Aerobic digestion after solubilization)) requires less ozone. In the method for reducing the amount of activated sludge according to the present invention, an interesting effect was observed when the biologically treated sludge digested in the aerobic digestion tank was subjected to solid-liquid separation by a membrane separation means. That is, it was recognized that membrane contamination was reduced in membrane separation. For this reason, in the conventionally known excess sludge treatment step, it is necessary to perform solid-liquid separation by a precipitation method, whereas in the present invention, even if solid-liquid separation is performed by more efficient membrane separation means, there is almost no need to replace the separation membrane. The advantage of sufficient use was recognized. The experimental conditions based on the process of FIG. 1 are shown in Table 1. Excess activated sludge from sewage (solid concentration: 5.0 g / liter) was treated according to the treatment flow shown in FIG.
The sludge throughput is 10 liters / day (50 g / day).
The volume of the aerobic digestion tank 2 used in the aerobic digestion process is 70
Liter, the digestion tank 2 is aerated with air, the amount of dissolved oxygen in the liquid to be treated in the tank is maintained at 5 to 6 mg / liter, the temperature in the digestion tank 1 is 25 ° C., and the sludge concentration is 5 to 6 g. / Liter. The biologically treated sludge generated by the aerobic digestion is subjected to solid-liquid separation by a precipitation method, and the separated water separated there is discharged out of the system. Most of the separated sludge 4 is returned to the aerobic digestion tank 2 as returned sludge 5. I will send it back. A part of the separated sludge is used as the transfer sludge 6 in the ozone oxidation tank 7 having the specifications shown in Table 1 below.
Then, ozone 8 is added to the sludge, and the sludge is solubilized by an oxidation reaction. The solubilized sludge 9 is returned to the aerobic digestion tank 2 together with the return sludge 5. [Table 1] As a result of continuing the test under these conditions for 9 months, 96% of the total weight of the supplied excess activated sludge (9 kg) was decomposed, and the amount of sludge discharged outside the system was very small. Advantages of the Invention The effect of reducing excess activated sludge is remarkably large, and the sludge treatment and disposal process is rationalized. The amount of sludge discharged out of the system can be made very small. 2. Since the amount of ozone used for activated sludge is significantly reduced, the cost of adding ozone is reduced.
【図面の簡単な説明】
【図1】活性汚泥を好気性消化した後その分離汚泥の一
部をオゾン酸化する本発明の汚泥減量化の工程フローを
示す。
【図2】活性汚泥を直接オゾン酸化する従来の汚泥減量
化の工程フローを示す。
【符号の説明】
1 供給活性汚泥
2 好気性消化槽
3 固液分離槽
4 分離汚泥
5 返送汚泥
6 移送汚泥
7 オゾン酸化槽
8 オゾン
9 可溶化汚泥
10 供給生物汚泥
11 オゾン酸化槽
12 好気性消化槽
13 沈澱槽
14 返送汚泥BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a process flow of sludge reduction according to the present invention in which activated sludge is subjected to aerobic digestion and then a part of the separated sludge is ozone-oxidized. FIG. 2 shows a process flow of conventional sludge reduction by directly oxidizing activated sludge with ozone. [Description of Signs] 1 Activated activated sludge 2 Aerobic digestion tank 3 Solid-liquid separation tank 4 Separated sludge 5 Returned sludge 6 Transfer sludge 7 Ozone oxidation tank 8 Ozone 9 Solubilized sludge 10 Supply biological sludge 11 Ozone oxidation tank 12 Aerobic digestion Tank 13 Settling tank 14 Returned sludge
Claims (1)
される余剰活性汚泥を、好気性消化した後固液分離し、
該固液分離で分離された分離汚泥の大部分を前記好気性
消化工程に返送すると共に、該分離汚泥の一部にオゾン
を添加して処理し、前記分離汚泥の大部分と共に前記好
気性消化工程に供給することを特徴とする活性汚泥の好
気性消化方法。(57) [Claims] [Claim 1] Excess activated sludge discharged from an activated sludge treatment facility of organic wastewater is subjected to aerobic digestion and then to solid-liquid separation.
Most of the separated sludge separated by the solid-liquid separation is returned to the aerobic digestion step, and ozone is added to a part of the separated sludge for treatment, and the aerobic digestion is performed together with most of the separated sludge. An aerobic digestion method for activated sludge, which is supplied to a process.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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JP34374196A JP3447037B2 (en) | 1995-12-25 | 1996-12-24 | Aerobic digestion of activated sludge |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP7-337058 | 1995-12-25 | ||
JP33705895 | 1995-12-25 | ||
JP34374196A JP3447037B2 (en) | 1995-12-25 | 1996-12-24 | Aerobic digestion of activated sludge |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH09234497A JPH09234497A (en) | 1997-09-09 |
JP3447037B2 true JP3447037B2 (en) | 2003-09-16 |
Family
ID=26575663
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP34374196A Expired - Fee Related JP3447037B2 (en) | 1995-12-25 | 1996-12-24 | Aerobic digestion of activated sludge |
Country Status (1)
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JP (1) | JP3447037B2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
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JP4622057B2 (en) * | 2000-07-05 | 2011-02-02 | 日本下水道事業団 | Organic wastewater treatment method |
EP2189422B1 (en) | 2007-08-28 | 2015-06-03 | Diamond Engineering Co., Ltd. | Activated sludge material, reduction method of excess sludge amount in bioreactor, and maintenance method of bioreactor |
-
1996
- 1996-12-24 JP JP34374196A patent/JP3447037B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
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JPH09234497A (en) | 1997-09-09 |
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