JP3574539B2

JP3574539B2 - Flat membrane element

Info

Publication number: JP3574539B2
Application number: JP30125896A
Authority: JP
Inventors: 雅志別府
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 1996-10-25
Filing date: 1996-10-25
Publication date: 2004-10-06
Anticipated expiration: 2016-10-25
Also published as: JPH10128080A

Description

【０００１】
【発明の属する技術分野】
本発明は、し尿、下水、家庭排水、工場排水等の汚水処理に使用する浸漬型膜分離装置の膜エレメントに関するものである。
【０００２】
【従来の技術】
近来、し尿、下水、家庭排水、工場排水（以下、汚水と称する）の伝統的な処理方法である重力分離活性汚泥処理法（曝気槽で微生物分解処理を行い、この処理汚水を沈殿分離室に導き、活性汚泥を重力分離により分離し、その分離汚泥の一部を曝気槽に返送する方法）に代替する方法として、膜分離活性汚泥処理法が注目されている。
この処理法においては、固液分離を膜モジュ−ルによる濾過で行い、濾過液を取出し、余剰汚泥を直接曝気槽から引き抜いており、▲１▼曝気槽のＭＬＳＳ（混合液浮遊性固形物）を重力分離法に較べて著しく高くできるので、曝気槽を重力分離法の場合に較べて相当に縮小でき、更に沈殿分離室が不要であるので、装置全体を小型化できる、▲２▼曝気槽内のＭＬＳＳ濃度を高く維持できるので、重力分離法とは異なり、余剰汚泥処理に際しての脱水を軽減できる、▲３▼運転エネルギ−の省力化を図ることができる、等の利点がある。
【０００３】
本出願人においては、膜分離法による汚水処理装置として、「散気装置を有し、膜面に沿い鉛直方向通路を有する膜モジュ−ルを前記散気装置の直上に配設し、該膜装置の膜体濾過側を負圧とするための手段を設けた散気式曝気槽」を既に提案した（特公平４−７０９５８号、特許第１８７４８８１号）。
この装置における膜モジュ−ルには、平膜エレメントを相互間に鉛直方向通路を保持するように並設したものが使用され、その平膜エレメントには、図７の（イ）及び図７の（ロ）〔図７の（イ）におけるロ−ロ断面図〕に示すように、濾過液取出し口２０６’を有する枠体２１’内に濾過液流路材２３’を納め、その枠体２１’の両側に平膜２２’を配し、図７の（ハ）に示すように各平膜の外面周囲部と枠体面とにまたがり接着剤ａ’を塗布して平膜の周囲部裏面と枠体面との間を接着剤の浸透により接着したものが使用されている。
【０００４】
この散気式曝気槽を使用して汚水を処理するには、散気装置からの噴出エアのエア−リフト効果で槽内原液を旋回させ、汚水中の有機物を空気との接触下、活性汚泥で吸着・代謝分解させ、有機物を減少させると共に活性汚泥を増殖させ、膜エレメントの膜面に沿う気液混合上昇流で膜面での汚泥ゲル層の生成を抑制しつつ膜エレメントの濾過液側を減圧して膜間差圧を発生させ、この膜間差圧下で活性汚泥液から水を濾過により分離していく。
この膜分離においては、膜エレメントの膜面に沿う気液混合上昇流で膜面での汚泥ゲル層の生成を抑制しているが、膜エレメント内が減圧され膜面に活性汚泥が吸引されるので、ゲル層の生成速度がかなり急速である。
而るに、膜エレメントの濾過液側の減圧を間歇的に行うと、膜面に付着している活性汚泥を減圧０のときに膜面での吸引から解除し得ると共に膜を無張力状態にして膜面に沿う気液混合上昇流で膜面をよく振動させ得るので、すでに付着した活性汚泥をある程度剥離除去でき、ゲル層の生成速度を遅くし得て濾過流束の低下軽減に有効である。
【０００５】
【発明が解決しようとする課題】
しかしながら、膜面の振動が激しくなり膜の枠体接着箇所に複雑な引張り力が作用する結果、膜と枠体との間の封止・固定が早期に破損され易い。
【０００６】
本発明の目的は、内側を濾過液側とする膜エレメントを原液中に浸漬し、散気手段により膜エレメントをエア−スクラビングしつつ膜エレメントの濾過液側を間歇的に減圧して原液を濾過処理する膜分離装置における膜エレメントのエア−スクラビングに対する封止安定性を向上させ、間歇的減圧のもとでも膜分離装置を安全に運転できるようにすることにある。
【０００７】
【課題を解決するための手段】
本発明に係る平膜エレメントは、内側を濾過液側とする膜エレメントを原液中に浸漬し、散気手段により膜エレメントをエア−スクラビングしつつ膜エレメントの濾過液側を減圧して原液を濾過処理する膜分離装置の膜エレメントであり、枠体の両側に平膜を配し、各平膜の周囲部裏面と枠体との接触面を塗布接着剤により接着し、各平膜の周囲部表面に枠体の内周位置を越えて接着剤を塗布したことを特徴とする構成である。
【０００８】
【発明の実施の形態】
以下、図面を参照しつつ本発明の実施の形態について説明する。
図１は本発明に係る平膜エレメントの接着剤封止構造を示し、平膜２２の周囲部の裏面と枠体２１の側面との接触面を塗布接着剤ａ_１で接着し、平膜２２の周囲部表面に枠体２１の内周位置ｐを越えて接着剤ａ_２（接着剤と同一接着剤）を塗布してあり、接着剤には、例えば、エポキシ樹脂、ウレタン樹脂、ホットメルト樹脂等を使用できる。
この接着剤封止構造においては、図７の（ハ）に示すように平膜周囲部の裏面と枠体面との間を接着剤ａ’の浸透で接着する場合とは異なり、図１に示すように枠体内周縁端ｐに至る全接触面を接着剤で接着できるために平膜の引張りに対し高い強度を呈する。
また、各平膜の周囲部表面に枠体の内周位置箇所を覆って接着剤を塗布しているので、図８に示すように平膜周囲部の裏面と枠体面との間のみを接着剤ａ”の塗布により接着する場合とは異なり、枠体内周縁端ｐの角から隔離した位置を振動支点にでき支点反力を緩和できるため、耐振動性にも優れている。
このため、後述する実施例と比較例との対比からも明らかなように、膜エレメントのエア−スクラビングに対する封止安定性を飛躍的に向上できる。
【０００９】
図２の（イ）は本発明に係る平膜エレメントの一例を示す平面図、図２の（ロ）及び図２の（ハ）は図２の（イ）におけるロ−ロ断面図及びハ−ハ断面図をそれぞれ示し、縦部材１８，１８と横部材１９，１９とをジョイナ−２０，…で連結して枠体２１を組立て、濾過液通路用スペ−サ２３（例えば、プラスチックネット、プラスチック不織布、トリコット等）の両端部を両縦部材１８，１８内にスリット１８１より挿入し、この濾過液通路用スペ−サ２３を挾む各平膜２２，２２の周囲を枠体２１の上下面に上記図１に示した構造で接着剤により封止固定してある。
【００１０】
図３の（イ）は縦部材１８の断面図を、図３の（ロ）は横部材１９の断面図を、図４の（イ）及び図４の（ロ）はジョイナ−の側面図及び正面図をそれぞれ示し、例えば、ＡＢＳ樹脂の射出または押出成形による製作できる。これらの部材を使用して上記枠体２１を組み立てるには、横部材１９の端部において両側面の溝１９１，１９１にジョイナ−２０の半受口２０１のスロット２０２を案内してジョイナ−２０を横部材１９の端部に嵌め込み、横部材１２の端部において高さ片半部外面にジョイナ−２０の半受口２０１を嵌合し、同他半部の中空内にジョイナ−２０のインサ−トプレ−ト部２０３の一部２０３’を嵌入し、更に、縦部材１８の端部において中空本体部１８２をジョイナ−２０の挿口２０４の外面上に嵌合すると共に縦部材１８の端部においてスリット部１８１内にジョイナ−２０のインサ−トプレ−ト部２０３の残部を嵌入させ、そして、ジョイナ−と横部材との境界及びジョイナ−と縦部材との境界をそれぞれ接着剤で封止・結着し、縦部材と横部材との接続を行い、この接合を４コ−ナで行って枠体を組み立てを終了する。このようにして組み立てた枠体においては、縦部材のスリット部の外側面と横部材の側面とが面一になっている。
本発明に係る平膜エレメントの寸法は、通常、縦５０〜１５０ｃｍ、横２０〜１００ｃｍ、厚み３ｍｍ〜６ｍｍとされる。
【００１１】
図５は本発明に係る平膜エレメントを使用した浸漬型平膜モジュ−ルを示している
図５において、２，…は上記した平膜エレメントを示し、複数枚を縦部材を相互に密接させて重ね、ジョイナ−２０，２０，…の側面同士を当接し、ジョイナ−２０，…にボルト２０５を通し、このボルトの締め付けにより一体化し、各平膜エレメントの上側両ジョイナ−の一方に濾過液取出し管２０６を平膜エレメントの一枚ごとに互い違いの位置にして取り付けてある。勿論、ジョイナ−のボルト挿通孔とボルトとの間は水密にシ−ルしてある。ジョイナ−におけるボルト挿通孔をジョイナ−内空洞より独立して穿孔すれば、このシ−ルは不要である。
上記において、ジョイナ−に鍔または耳部を設け、この鍔または耳部にボルト挿通孔を穿孔することもできる。
上記の本発明に係る平膜エレメントにおいては、平膜エレメントの縦部材１８，１８が相互に密接されており、実質上、上下のみに開放された周囲壁構造となっている。
【００１２】
図６は上記の膜モジュ−ルを使用した膜分離活性汚泥処理装置の一例を示す説明図である。
図６において、３１は開放式の被処理液槽である。平膜は浸漬型平膜モジュ−ルである。３２は膜エレメント２，…の濾過液集水管に連通した濾過水取出し配管である。３３はこの配管３２に設けた減圧ポンプであり、間歇駆動させるための制御回路を備えている。３４は濾過液貯水槽である。４１は原液供給配管、４２はこの配管４１に設けた液送ポンプである。
５１，…は膜モジュ−ルの直下に配設した散気管である。５２は散気管５１，…に接続したブロワである。
【００１３】
この汚水処理装置により汚水を処理するには、この排水を貯槽に一旦貯え、図６において、この汚水を液送ポンプ４２により被処理液槽３１に供給し、ブロワ５２の駆動により散気管５１，…から空気を噴出させ、この噴出気流により槽内汚水を旋回させると共に吸引ポンプ３３の間歇的駆動により平膜エレメント２，…の濾過液通路側を間歇的に減圧し、汚水中の有機物を空気との接触下、好気性微生物により吸着・代謝分解させ、有機物を減少させると共に好気性微生物を増殖させ、膜エレメント２の濾過液側の減圧による膜間差圧のもとで水を膜濾過させ、これを濾過液貯水槽３４に貯えていく。
吸引ポンプ３３の間歇運転の停止時、上記減圧が行われず、従って、濾過は行われないが、ブロワ５２が連続駆動され、散気管５１，…からの噴出気流による槽内汚水の旋回が続行されたままであり、膜エレメント２の膜面に付着している活性汚泥が減圧吸引から解除されて散気管５１，…からのエアによるアアスクラビングで剥離除去されていく。
【００１４】
【実施例】
〔実施例〕
平膜エレメントは図２に示す構造とし、寸法は縦５７０ｍｍ、横４５０ｍｍ、厚み５ｍｍとし、平膜には公称孔径０．４μｍ、膜面積０．３ｍ^２のポリオレフィン系限外濾過膜を使用し、平膜周囲の接着封止にはウレタン樹脂を用い、図１に示す構成とした。
この平膜エレメント１５枚を相互間隔８ｍｍで並設した膜モジュ−ルを水槽内に浸漬し、下方から平膜エレメント１枚当たり、５リットル／分、１０リットル／分、５０リットル／分の空気量でエアスクラビングし、膜の剥離の有無を観察したところ表１の通りであった。
【００１５】
〔比較例１〕
図７の（ハ）に示す構成で平膜周囲の接着封止を行った以外、実施例に同じとして膜の剥離の有無を観察したところ表１の通りであった。
〔比較例２〕
図８に示す構成で平膜周囲の接着封止を行った以外、実施例に同じとして膜の剥離の有無を観察したところ表１の通りであった。
【００１６】
【表１】

【００１７】
【発明の効果】
本発明に係る平膜エレメントにおいては、表１から確認できる通り、膜エレメント内が常圧で膜間差圧の作用が無くて膜が振動しやすい状態でエアスクラビングを受けても、枠体と平膜との封止固定状態を安定に保持でき、散気手段により膜エレメントをエア−スクラビングしつつ膜エレメントの濾過液側を間歇的に減圧し、この間歇的減圧のもとで膜汚染の進行を遅らせて濾過流束の低下速度を遅延させる場合でも、膜分離装置を安全に運転できる。
【図面の簡単な説明】
【図１】本発明に係る平膜エレメントにおける平膜周囲部の接着封止構造を示す説明図である。
【図２】本発明に係る平膜エレメントを示す図面である。
【図３】図３の（イ）は図２における膜エレメントの支持体の縦部材の断面図、図３の（ロ）は同じく横部材の断面図である。
【図４】図３における平膜エレメントの支持体のジョイナ−を示す図面である。
【図５】本発明に係る膜エレメントを使用した膜モジュ−ルの一例を示す図面である。
【図６】本発明に係る膜エレメントを使用した膜モジュ−ルで膜分離活性汚泥処理するための装置の一例を示す説明図である。
【図７】従来の平膜エレメントを示す図面である。
【図８】従来の平膜エレメントの平膜の接着剤による封止固定構造の別例を示す図面である。
【符号の説明】
１１平膜
１２平膜の周囲部
１３孔
１４支持体
１５両面粘着テ−プ
１６接着剤
１７クリアランス[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a membrane element of a submerged membrane separation apparatus used for treating wastewater such as night soil, sewage, domestic wastewater, industrial wastewater, and the like.
[0002]
[Prior art]
Recently, a gravity separation activated sludge treatment method (microbial decomposition treatment is performed in an aeration tank, which is a traditional treatment method for human waste, sewage, domestic wastewater, and industrial wastewater (hereinafter referred to as wastewater). The membrane separation activated sludge treatment method is drawing attention as an alternative to the method in which the activated sludge is separated by gravity separation and a part of the separated sludge is returned to the aeration tank.
In this treatment method, solid-liquid separation is performed by filtration using a membrane module, a filtrate is taken out, and excess sludge is directly drawn out from an aeration tank. (1) MLSS (mixed liquid suspended solids) in an aeration tank The aeration tank can be remarkably higher than the gravity separation method, so that the aeration tank can be considerably reduced as compared with the gravity separation method, and further, the sedimentation separation chamber is unnecessary, so that the entire apparatus can be downsized. Since the MLSS concentration in the inside can be kept high, there are advantages that, unlike the gravity separation method, dehydration during the treatment of excess sludge can be reduced, and (3) labor saving of operating energy can be achieved.
[0003]
In the present applicant, as a sewage treatment apparatus by the membrane separation method, "a membrane module having an air diffuser and having a vertical passage along the membrane surface is disposed directly above the air diffuser, A diffusing aeration tank provided with a means for reducing the pressure on the membrane filtration side of the apparatus "has already been proposed (Japanese Patent Publication No. 4-70958, Japanese Patent No. 1874881).
As the membrane module in this apparatus, one in which flat membrane elements are juxtaposed so as to maintain a vertical passage therebetween is used, and the flat membrane elements are shown in FIGS. (B) As shown in FIG. 7 (a), a filtrate flow channel member 23 'is placed in a frame 21' having a filtrate outlet 206 '. The flat film 22 'is disposed on both sides of the flat film, and as shown in FIG. 7 (c), an adhesive a' is applied over the outer peripheral portion and the frame surface of each flat film, and the peripheral portion rear surface of the flat film is formed. What has adhere | attached by the penetration of an adhesive between the frame body surfaces is used.
[0004]
To treat sewage using this aeration tank, the undiluted solution in the tank is swirled by the air-lift effect of the air ejected from the aeration device, and the organic matter in the sewage is contacted with air to activate activated sludge. Adsorbed and metabolically decomposed to reduce organic matter and increase the activated sludge, while suppressing the formation of a sludge gel layer on the membrane surface by the gas-liquid mixed upflow along the membrane surface of the membrane element and the filtrate side of the membrane element Is reduced to generate a transmembrane pressure, and water is separated from the activated sludge by filtration under the transmembrane pressure.
In this membrane separation, generation of a sludge gel layer on the membrane surface is suppressed by a gas-liquid mixed ascending flow along the membrane surface of the membrane element, but the inside of the membrane element is depressurized and activated sludge is sucked into the membrane surface. Thus, the rate of formation of the gel layer is quite rapid.
If the pressure on the filtrate side of the membrane element is intermittently reduced, the activated sludge adhering to the membrane surface can be released from suction on the membrane surface when the pressure is reduced to zero, and the membrane is brought into a non-tension state. Because the membrane surface can be vibrated well by the gas-liquid mixed ascending flow along the membrane surface, the activated sludge that has already adhered can be peeled and removed to some extent, the gel layer generation speed can be reduced, and the reduction of the filtration flux is effective. is there.
[0005]
[Problems to be solved by the invention]
However, as the vibration of the film surface becomes intense and a complicated tensile force acts on a portion where the film is bonded to the frame, the sealing and fixing between the film and the frame are easily damaged at an early stage.
[0006]
An object of the present invention is to filter a stock solution by immersing a membrane element having a filtrate side on the inside in a stock solution and intermittently reducing the pressure of the filtrate side of the membrane element while air-scrubbing the membrane element by a diffuser. An object of the present invention is to improve the sealing stability of a membrane element against air scrubbing in a membrane separator to be treated, and to enable the membrane separator to operate safely even under intermittent pressure reduction.
[0007]
[Means for Solving the Problems]
In the flat membrane element according to the present invention, the membrane element whose inside is the filtrate side is immersed in the stock solution, and the membrane element is air-scrubbed by a diffuser means while the filtrate side of the membrane element is depressurized to filter the stock solution. A membrane element of a membrane separation device to be processed.Flat membranes are arranged on both sides of the frame, and the contact surface between the back of the periphery of each flat membrane and the frame is adhered with a coating adhesive. An adhesive is applied to the surface beyond the inner peripheral position of the frame.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Figure 1 shows the adhesive sealing structure of a flat membrane element according to the present invention, adhered to contact surfaces of the side surface of the back and the frame 21 of the periphery of the flat film 22 by coating the adhesive a _1, a flat film 22 An adhesive a ₂ (the same adhesive as the adhesive) is applied to the peripheral surface of the frame beyond the inner peripheral position p of the frame 21, and the adhesive is, for example, an epoxy resin, a urethane resin, a hot melt resin. Etc. can be used.
In this adhesive sealing structure, as shown in FIG. 7C, unlike the case of bonding between the back surface around the flat membrane and the surface of the frame by the penetration of the adhesive a ', as shown in FIG. As described above, the entire contact surface up to the peripheral edge p in the frame can be bonded with an adhesive, so that the flat film exhibits high strength against tension.
Further, since the adhesive is applied to the peripheral surface of each flat film so as to cover the inner peripheral position of the frame, only the back surface of the peripheral portion of the flat film and the surface of the frame are bonded as shown in FIG. Unlike the case where the adhesive is applied by applying the agent a ″, the position isolated from the corner of the peripheral edge p in the frame can be used as the vibration fulcrum, and the fulcrum reaction force can be reduced, so that the vibration resistance is excellent.
For this reason, as will be apparent from a comparison between an example and a comparative example described later, the sealing stability of the membrane element against air-scrubbing can be remarkably improved.
[0009]
FIG. 2A is a plan view showing an example of the flat membrane element according to the present invention, and FIGS. 2B and 2C are cross-sectional views taken along the roll and FIG. A sectional view is shown, and the frame member 21 is assembled by connecting the

vertical members

18, 18 and the

horizontal members

19, 19 with the joiners 20,..., And the filtrate passage spacer 23 (for example, plastic net, plastic Non-woven fabric, tricot, etc.) are inserted into both

longitudinal members

18, 18 through slits 181, and the periphery of each flat membrane 22, which sandwiches the filtrate passage spacer 23, is the upper and lower surfaces of the frame 21. Is sealed and fixed with an adhesive in the structure shown in FIG.
[0010]
3A is a sectional view of the vertical member 18, FIG. 3B is a sectional view of the horizontal member 19, and FIGS. 4A and 4B are side views of the joiner. The front views are respectively shown and can be manufactured by, for example, injection or extrusion molding of ABS resin. To assemble the frame body 21 using these members, the slot 202 of the semi-receiving port 201 of the joiner 20 is guided to the

grooves

191 and 191 on both sides at the end of the horizontal member 19, and the joiner 20 is At the end of the horizontal member 19, the half receiving hole 201 of the joiner 20 is fitted to the outer surface of one half of the height at the end of the horizontal member 12, and the inserter of the joiner 20 is inserted into the hollow of the other half. A part 203 ′ of the plate portion 203 is fitted, and a hollow main body 182 is fitted on the outer surface of the insertion opening 204 of the joiner 20 at the end of the vertical member 18, and at the end of the vertical member 18. The remaining portion of the insert plate portion 203 of the joiner 20 is fitted into the slit portion 181, and the boundary between the joiner and the horizontal member and the boundary between the joiner and the vertical member are sealed and bonded with an adhesive. Wear, with vertical members The connection with the lateral member is performed, and this joining is performed with four corners, and the frame is assembled. In the frame assembled in this manner, the outer surface of the slit portion of the vertical member and the side surface of the horizontal member are flush.
The dimensions of the flat membrane element according to the present invention are usually 50 to 150 cm in length, 20 to 100 cm in width, and 3 mm to 6 mm in thickness.
[0011]
5 shows an immersion type flat membrane module using the flat membrane element according to the present invention. In FIG. 5, 2,... Show the above flat membrane elements, and a plurality of the vertical membrane members are brought into close contact with each other. , Abutting the side surfaces of the

joiners

20, 20,..., Passing the bolts 205 through the joiners 20,..., And integrating them by tightening the bolts; The take-out tube 206 is attached to each of the flat membrane elements in an alternate position. Of course, the space between the bolt insertion hole of the joiner and the bolt is sealed watertight. This seal is unnecessary if the bolt insertion hole in the joiner is formed independently from the inner cavity of the joiner.
In the above, a flange or an ear may be provided on the joiner, and a bolt insertion hole may be formed in the flange or the ear.
In the above-mentioned flat membrane element according to the present invention, the

vertical members

18, 18 of the flat membrane element are in close contact with each other, and have a peripheral wall structure which is substantially opened only up and down.
[0012]
FIG. 6 is an explanatory view showing an example of a membrane separation activated sludge treatment apparatus using the above-mentioned membrane module.
In FIG. 6, reference numeral 31 denotes an open type liquid tank to be treated. The flat membrane is an immersion type flat membrane module. Reference numeral 32 denotes a filtered water discharge pipe connected to the filtrate collecting pipe of the membrane element 2,. Reference numeral 33 denotes a decompression pump provided in the pipe 32, which has a control circuit for intermittent driving. 34 is a filtrate storage tank. Reference numeral 41 denotes a stock solution supply pipe, and reference numeral 42 denotes a liquid feed pump provided in the pipe 41.
Numerals 51,... Are air diffusers disposed immediately below the membrane module. 52 is a blower connected to the air diffusers 51,.
[0013]
In order to treat sewage by this sewage treatment apparatus, this wastewater is temporarily stored in a storage tank, and in FIG. 6, this sewage is supplied to the liquid tank 31 to be treated by the liquid feed pump 42, and the air diffuser 51, Air is blown out of the tank, and the sewage in the tank is swirled by the blown air flow, and the filtrate passage side of the flat membrane elements 2 is intermittently depressurized by intermittent driving of the suction pump 33 to remove organic matter in the sewage. Under contact with water, it is adsorbed and metabolized and decomposed by aerobic microorganisms to reduce organic matter and grow aerobic microorganisms. Water is subjected to membrane filtration under a transmembrane pressure difference due to reduced pressure on the filtrate side of the membrane element 2. This is stored in the filtrate storage tank 34.
When the intermittent operation of the suction pump 33 is stopped, the pressure reduction is not performed, and thus the filtration is not performed. However, the blower 52 is continuously driven, and the turning of the wastewater in the tank due to the airflow spouted from the diffusion pipes 51,. The activated sludge adhering to the membrane surface of the membrane element 2 is released from the reduced pressure suction, and is separated and removed by air scrubbing with air from the air diffusers 51,.
[0014]
【Example】
〔Example〕
The flat membrane element has the structure shown in FIG. 2, the dimensions are 570 mm in length, 450 mm in width, and 5 mm in thickness. The flat membrane uses a polyolefin-based ultrafiltration membrane with a nominal pore diameter of 0.4 μm and a membrane area of 0.3 m ² , Urethane resin was used for adhesive sealing around the flat film, and the structure shown in FIG. 1 was adopted.
A membrane module in which 15 flat membrane elements are juxtaposed at an interval of 8 mm is immersed in a water tank, and air at 5 liter / min, 10 liter / min, and 50 liter / min per flat membrane element from below. Table 1 shows the results of air scrubbing with the amount and observation of the presence or absence of peeling of the film.
[0015]
[Comparative Example 1]
Table 1 shows the result of observing the presence or absence of peeling of the film in the same manner as in the example, except that the sealing around the flat film was performed by the configuration shown in FIG.
[Comparative Example 2]
Table 1 shows the result of observation of the presence or absence of peeling of the film in the same manner as in the example, except that the sealing around the flat film was performed with the configuration shown in FIG.
[0016]
[Table 1]

[0017]
【The invention's effect】
In the flat membrane element according to the present invention, as can be confirmed from Table 1, even if the membrane is subjected to air scrubbing in a state where the inside of the membrane element is at normal pressure and there is no action of the transmembrane pressure difference and the membrane is easily vibrated, the frame body and The sealing and fixed state with the flat membrane can be maintained stably, and the filtrate side of the membrane element is intermittently depressurized while air-scrubbing the membrane element by the air diffuser. Even when the progress is slowed and the rate of decrease of the filtration flux is delayed, the membrane separation device can be safely operated.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an adhesive sealing structure around a flat membrane in a flat membrane element according to the present invention.
FIG. 2 is a drawing showing a flat membrane element according to the present invention.
3A is a cross-sectional view of a vertical member of a support of the membrane element in FIG. 2, and FIG. 3B is a cross-sectional view of a horizontal member.
FIG. 4 is a view showing a joiner of a support of the flat membrane element in FIG. 3;
FIG. 5 is a drawing showing an example of a membrane module using the membrane element according to the present invention.
FIG. 6 is an explanatory view showing an example of an apparatus for treating activated sludge with a membrane module using a membrane element according to the present invention.
FIG. 7 is a view showing a conventional flat membrane element.
FIG. 8 is a view showing another example of a conventional sealing and fixing structure of a flat membrane of a flat membrane element using an adhesive.
[Explanation of symbols]
11 Flat membrane 12 Peripheral part of flat membrane 13 Hole 14 Support 15 Double-sided adhesive tape 16 Adhesive 17 Clearance

Claims

A membrane element having a filtrate side on the inner side is immersed in a stock solution, and a membrane element of a membrane separation device for filtering the stock solution by depressurizing the filtrate side of the membrane element while air-scrubbing the membrane element by aeration means. There is a flat membrane on both sides of the frame body, the contact surface between the back surface of the peripheral portion of each flat film and the frame body is adhered with a coating adhesive, and the inner peripheral position of the frame body on the peripheral surface of each flat film. A flat membrane element characterized in that an adhesive is applied over the flat membrane element.