JPH07171358A - Method for backwashing ceramic membrane - Google Patents
Method for backwashing ceramic membraneInfo
- Publication number
- JPH07171358A JPH07171358A JP32480793A JP32480793A JPH07171358A JP H07171358 A JPH07171358 A JP H07171358A JP 32480793 A JP32480793 A JP 32480793A JP 32480793 A JP32480793 A JP 32480793A JP H07171358 A JPH07171358 A JP H07171358A
- Authority
- JP
- Japan
- Prior art keywords
- backwashing
- filtration
- ceramic membrane
- pressure
- rate
- 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.)
- Pending
Links
Landscapes
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はセラミック膜の逆洗方法
に関するものである。FIELD OF THE INVENTION The present invention relates to a method for backwashing a ceramic membrane.
【０００２】[0002]
【従来の技術】膜ろ過装置においては、ろ過の進行に伴
って膜表面にケーキ層が蓄積するために圧力損失が次第
に上昇することが避けられない。このために膜の裏側か
ら透過水を高流速で流すことによりケーキ層を剥離させ
る逆洗操作が必要である。またセラミック膜においては
ケーキ層による抵抗の他に、内部に固形物が詰まった
り、無機物が析出したり、微生物が繁殖してろ過抵抗を
増加させる場合があり、これらを内部閉塞と呼んでい
る。この内部閉塞は逆洗によって除去が困難であり、こ
のために逆洗を繰り返すとろ過抵抗の回復量は次第に低
下していく。2. Description of the Related Art In a membrane filtration device, it is inevitable that a pressure loss gradually increases because a cake layer accumulates on the membrane surface as the filtration progresses. For this reason, it is necessary to carry out a backwash operation in which the cake layer is peeled off by flowing permeated water from the back side of the membrane at a high flow rate. Further, in the ceramic membrane, in addition to the resistance due to the cake layer, solid matter may be clogged inside, inorganic matter may be precipitated, or microorganisms may propagate to increase filtration resistance, and these are called internal blockages. This internal blockage is difficult to remove by backwashing, and therefore, when backwashing is repeated, the recovery amount of filtration resistance gradually decreases.
【０００３】上記した逆洗は膜表面のケーキ層を剥離さ
せるためには有効な手段であるが、頻繁に逆洗を行うこ
とは逆効果となる可能性がある。すなわち、逆洗に使用
される透過水にも僅かながら膜を詰まらせる原因となる
物質が含まれているため、頻繁に逆洗を行うと却って内
部閉塞を進行させる可能性がある。またケーキ層は内部
閉塞に対する保護層としても機能しているため、過剰な
逆洗により内部閉塞を進行させることも考えられる。従
ってどのようなタイミングで逆洗を行うかはろ過装置の
運転管理を行ううえで重要なポイントとなる。The above-mentioned backwashing is an effective means for peeling off the cake layer on the surface of the membrane, but frequent backwashing may be counterproductive. That is, since the permeated water used for backwashing contains a slight amount of a substance that causes the clogging of the membrane, frequent backwashing may rather cause internal clogging to proceed. Further, since the cake layer also functions as a protective layer against internal clogging, it may be possible to promote internal clogging by excessive backwashing. Therefore, the timing of backwashing is an important point for operation management of the filtration device.
【０００４】従来のセラミック膜の逆洗タイミングの決
定方法としては、一定の時間間隔で逆洗する方法と、ろ
過抵抗が所定のレベルに達したときに逆洗する方法のい
ずれかが採用されていた。ところが一定の時間間隔で逆
洗する方法では最初のうちは過剰な逆洗を行うこととな
り、却って内部閉塞を進行させる結果となる。またろ過
抵抗が所定のレベルに達したときに逆洗する方法では、
ある程度まで内部閉塞が進行した後に逆洗する傾向とな
り、逆洗によるろ過抵抗の回復率が不十分となり易い。As a conventional method for determining the backwashing timing of a ceramic membrane, either a backwashing method at regular time intervals or a backwashing method when the filtration resistance reaches a predetermined level is adopted. It was However, in the method of backwashing at regular time intervals, excessive backwashing is performed at first, which results in the progress of internal blockage. Also, in the method of backwashing when the filtration resistance reaches a predetermined level,
After internal clogging has progressed to some extent, backwashing tends to occur, and the recovery rate of filtration resistance due to backwashing tends to be insufficient.
【０００５】[0005]
【発明が解決しようとする課題】本発明は上記した従来
の問題点を解決し、内部閉塞を進行させる原因となる過
剰な逆洗を防止し、十分なろ過抵抗の回復率が得られる
適切な逆洗を行うことができるセラミック膜の逆洗方法
を提供するためになされたものである。SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, prevents excessive backwashing that causes the progress of internal blockage, and provides a suitable filtration resistance recovery rate. The purpose of the present invention is to provide a method for backwashing a ceramic membrane, which enables backwashing.
【０００６】[0006]
【課題を解決するための手段】上記の課題を解決するた
めになされた第１の発明は、セラミック膜のろ過抵抗の
上昇速度が所定値に達したときに逆洗を行うことを特徴
とするものである。また第２の発明は、セラミック膜の
ろ過抵抗の上昇速度が所定値に達するまでのろ過時間と
ろ過開始初期圧力との関係を予め求めておき、そのろ過
時間に達したときに逆洗を行うことを特徴とするもので
ある。The first invention made to solve the above problems is characterized in that backwashing is performed when the rising speed of the filtration resistance of the ceramic membrane reaches a predetermined value. It is a thing. In the second aspect of the invention, the relationship between the filtration time until the rate of increase of the filtration resistance of the ceramic membrane reaches a predetermined value and the initial filtration start pressure is obtained in advance, and backwashing is performed when the filtration time is reached. It is characterized by that.
【０００７】[0007]
【作用】本発明者の研究結果によれば、同一膜、同一原
水を使用しても、膜の内部閉塞状態によってろ過抵抗の
上昇速度が変化することがわかった。すなわちろ過抵抗
の絶対値ではなく、ろ過抵抗の上昇速度が膜の内部閉塞
状態を表すことがわかった。そこで第１の発明のように
セラミック膜のろ過抵抗の上昇速度が所定値に達したと
きに逆洗を行うようにすれば、十分なろ過抵抗の回復率
が得られる適切なタイミングで逆洗が行えることとな
る。また第２の発明は原水性状が安定している場合に有
効な方法であり、ろ過開始初期圧力を測定すればその後
はろ過時間のみによって逆洗を管理することができるの
で、運転管理が容易となる利点がある。According to the research results of the present inventor, it was found that even when the same membrane and the same raw water are used, the increasing rate of the filtration resistance changes depending on the internal clogging state of the membrane. That is, it was found that the rate of increase in filtration resistance, rather than the absolute value of filtration resistance, represents the state of internal clogging of the membrane. Therefore, if the backwashing is performed when the rising speed of the filtration resistance of the ceramic membrane reaches a predetermined value as in the first aspect of the invention, the backwashing is performed at an appropriate timing so that a sufficient recovery rate of the filtration resistance is obtained. It will be possible. The second invention is an effective method when the state of raw water is stable. Since the backwash can be controlled only by the filtration time after that by measuring the initial pressure at the start of filtration, it is easy to manage the operation. There are advantages.
【０００８】[0008]
【実施例】以下に本発明を実施例によって更に詳細に説
明する。図１は横軸にセラミック膜のろ過圧力の上昇速
度を取り、縦軸に圧力回復率を取ったグラフである。こ
こでろ過抵抗の上昇速度とは、例えば、ろ過運転中の１
時間当たりのろ過圧力の上昇量を意味する値であり、圧
力回復率とは逆洗による圧力回復量をろ過開始初期圧力
で割った値である。この図１は一定時間間隔の逆洗を繰
り返しながら収集した多数のデータをプロットしたもの
であるが、ろ過圧力の上昇速度が0.03kgf/cm2/hrを越え
ると、圧力回復率の値が不連続的に低下することがわか
る。またこのグラフは、ろ過抵抗の上昇速度が0.03kgf/
cm2/hrを越えた後に逆洗を行うのでは遅すぎるが、それ
よりも早い時期であればどのタイミングで逆洗を行って
も圧力回復率の値に大差がないことを意味している。EXAMPLES The present invention will be described in more detail below with reference to examples. FIG. 1 is a graph in which the horizontal axis represents the rate of increase in the filtration pressure of the ceramic membrane and the vertical axis represents the pressure recovery rate. Here, the rate of increase in filtration resistance is, for example, 1 during filtration operation.
It is a value that means the amount of increase in filtration pressure per unit time, and the pressure recovery rate is the value obtained by dividing the amount of pressure recovery by backwashing by the initial filtration start pressure. This Figure 1 is a plot of a large number of data collected while repeating backwashing at a certain time interval, but when the rising rate of filtration pressure exceeds 0.03 kgf / cm 2 / hr, the value of the pressure recovery rate becomes unclear. It can be seen that it decreases continuously. This graph also shows that the rate of increase in filtration resistance is 0.03kgf /
It is too late to perform backwashing after exceeding cm 2 / hr, but it means that there is no significant difference in pressure recovery rate at any time earlier if backwashing is performed. .
【０００９】この結果、ろ過圧力の上昇速度が0.03kgf/
cm2/hrを越える直前に逆洗を行えば、高い圧力回復率を
維持しつつ過剰な逆洗を防止できることとなる。このた
め、第１の発明ではろ過運転中に１分毎にろ過圧力を測
定し、ろ過圧力の上昇速度を計算し、ろ過圧力の上昇値
が所定値（実施例では0.03kgf/cm2/hr）に達したときに
セラミック膜の逆洗を行う。図２はこのようにして第１
の発明によって逆洗を行った場合と、従来法により一定
時間間隔で逆洗を行った場合とについて、ろ過開始初期
圧力（逆洗直後の圧力）の変化を３０日間にわたり測定
した結果である。従来法では４時間毎に逆洗を行ったの
に対して、第１の発明では平均逆洗間隔は8.6 時間であ
り、ろ過頻度は従来法の半分以下となっている。しか
も、第１の発明による逆洗法によればろ過開始初期圧力
の上昇は従来法よりもはるかに小さく、長期間にわたり
優れた圧力回復率が達成されていることが分かる。As a result, the rate of increase in filtration pressure is 0.03 kgf /
If backwashing is performed immediately before exceeding cm 2 / hr, it is possible to prevent excessive backwashing while maintaining a high pressure recovery rate. Therefore, in the first invention, the filtration pressure is measured every one minute during the filtration operation, the rate of increase in the filtration pressure is calculated, and the increase value of the filtration pressure is a predetermined value (0.03 kgf / cm 2 / hr in the embodiment). ) Is reached, the ceramic membrane is backwashed. FIG. 2 is thus the first
Fig. 3 shows the results of measuring the change in initial pressure of filtration (pressure immediately after backwashing) over a period of 30 days between the case where backwashing was performed according to the invention of 1. and the case where backwashing was performed by a conventional method at regular time intervals. In the conventional method, backwashing was performed every 4 hours, whereas in the first invention, the average backwashing interval was 8.6 hours, and the filtration frequency was less than half that of the conventional method. Moreover, according to the backwashing method of the first invention, the increase in the initial pressure of filtration start is much smaller than that of the conventional method, and it can be seen that an excellent pressure recovery rate is achieved for a long period of time.
【００１０】以上に説明した第１の発明では、ろ過運転
中に常時ろ過圧力を測定する必要がある。しかし原水の
性状が一定である場合には、図３のグラフに示すように
ろ過圧力の上昇速度が所定値に達するまでの時間と、ろ
過開始初期圧力との間には強い相関関係がある。そこで
第２の発明ではこのような関係式を予備実験等によって
予め求めておき、そのろ過時間に達したときに逆洗を行
う。すなわち逆洗後のろ過開始初期圧力が例えば0.3kgf
/cm2であったとすると、図３により求められた6.5 時間
経過後に次の逆洗を行うようにする。このようにすれば
ろ過運転中に常時ろ過圧力上昇速度を計算する必要はな
く、しかも前記した第１の発明と同様の結果が得られる
こととなる。In the first invention described above, it is necessary to constantly measure the filtration pressure during the filtration operation. However, when the property of the raw water is constant, as shown in the graph of FIG. 3, there is a strong correlation between the time until the rising speed of the filtration pressure reaches a predetermined value and the initial filtration start pressure. Therefore, in the second invention, such a relational expression is obtained in advance by a preliminary experiment or the like, and backwashing is performed when the filtration time is reached. That is, the initial pressure for starting filtration after backwashing is, for example, 0.3 kgf.
If it is / cm 2 , the next backwash should be performed after 6.5 hours obtained from Fig. 3. By doing so, it is not necessary to constantly calculate the filtration pressure increase rate during the filtration operation, and moreover, the same result as in the above-mentioned first invention can be obtained.
【００１１】なお、実施例ではろ過抵抗の上昇速度が0.
03kgf/cm2/hrに達したときに逆洗を行うようにしたが、
この値自体はセラミック膜の種類や原水の性状等によっ
て変化するので、絶対的なものではない。In the embodiment, the rate of increase in filtration resistance is 0.
I tried to backwash when it reached 03kgf / cm 2 / hr.
This value itself is not absolute because it changes depending on the type of ceramic membrane and the properties of raw water.
【００１２】[0012]
【発明の効果】以上に説明したように、本発明のセラミ
ック膜の逆洗方法によれば、従来使用されていなかった
ろ過抵抗の上昇速度を逆洗開始の指標として採用するこ
とにより、内部閉塞を進行させる原因となる過剰な逆洗
を防止しつつ、十分なろ過抵抗の回復率が得られる適切
な逆洗を行うことができる。このように最適のタイミン
グで逆洗が行えるので、図２に示したように、従来法よ
りもはるかに優れた逆洗効果（圧力回復効果）を長期間
にわたって維持することが可能となる。また第２の発明
によれば、より簡素な方法で第１の発明と同一の効果が
得られる利点がある。As described above, according to the method for backwashing a ceramic membrane of the present invention, internal clogging is achieved by using the rate of increase in filtration resistance, which has not been used conventionally, as an index for starting backwashing. It is possible to perform an appropriate backwash that can obtain a sufficient recovery rate of filtration resistance while preventing an excessive backwash that causes the progress of the above. Since the backwashing can be performed at the optimum timing in this manner, as shown in FIG. 2, the backwashing effect (pressure recovery effect) far superior to that of the conventional method can be maintained for a long period of time. According to the second invention, there is an advantage that the same effect as the first invention can be obtained by a simpler method.
【図１】セラミック膜のろ過圧力の上昇速度と、圧力回
復率との関係を示すグラフである。FIG. 1 is a graph showing the relationship between the rate of increase in filtration pressure of a ceramic membrane and the pressure recovery rate.
【図２】第１の発明と従来法による逆洗後のろ過開始初
期圧力の推移を示すグラフである。FIG. 2 is a graph showing a transition of a filtration start initial pressure after backwashing by the first invention and a conventional method.
【図３】ろ過圧力の上昇速度が所定値に達するまでの時
間と、ろ過開始初期圧力との関係を示すグラフである。FIG. 3 is a graph showing the relationship between the time until the rising speed of the filtration pressure reaches a predetermined value and the initial filtration start pressure.
Claims (2)
セラミック膜のろ過抵抗の上昇速度が所定値に達したと
きに逆洗を行うことを特徴とするセラミック膜の逆洗方
法。1. When solid-liquid separation is performed using a shellac membrane,
A method for backwashing a ceramic membrane, which comprises performing backwashing when the rate of increase in filtration resistance of the ceramic membrane reaches a predetermined value.
定値に達するまでのろ過時間とろ過開始初期圧力との関
係を予め求めておき、そのろ過時間に達したときに逆洗
を行うことを特徴とするセラミック膜の逆洗方法。2. The relationship between the filtration time until the rise rate of the filtration resistance of the ceramic membrane reaches a predetermined value and the initial filtration start pressure is obtained in advance, and backwashing is performed when the filtration time is reached. Characteristic ceramic membrane backwashing method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32480793A JPH07171358A (en) | 1993-12-22 | 1993-12-22 | Method for backwashing ceramic membrane |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32480793A JPH07171358A (en) | 1993-12-22 | 1993-12-22 | Method for backwashing ceramic membrane |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07171358A true JPH07171358A (en) | 1995-07-11 |
Family
ID=18169902
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32480793A Pending JPH07171358A (en) | 1993-12-22 | 1993-12-22 | Method for backwashing ceramic membrane |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07171358A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11319516A (en) * | 1998-05-21 | 1999-11-24 | Nkk Corp | Water filtration apparatus and method for operating the same |
| WO2009143740A1 (en) * | 2008-05-30 | 2009-12-03 | 北京汉青天朗水处理科技有限公司 | Method and apparatus for cleaning a film seperating device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63294906A (en) * | 1987-05-26 | 1988-12-01 | Nippon Atom Ind Group Co Ltd | Method for operating hollow yarn membrane filter |
-
1993
- 1993-12-22 JP JP32480793A patent/JPH07171358A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63294906A (en) * | 1987-05-26 | 1988-12-01 | Nippon Atom Ind Group Co Ltd | Method for operating hollow yarn membrane filter |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11319516A (en) * | 1998-05-21 | 1999-11-24 | Nkk Corp | Water filtration apparatus and method for operating the same |
| WO2009143740A1 (en) * | 2008-05-30 | 2009-12-03 | 北京汉青天朗水处理科技有限公司 | Method and apparatus for cleaning a film seperating device |
| US9028622B2 (en) | 2008-05-30 | 2015-05-12 | Beijing Ecojoy Water Technology Co., Ltd. | Method and apparatus for cleaning a film seperating device |
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