JP4618073B2 - Method and apparatus for recovering water from CMP wastewater containing high TOC - Google Patents
Method and apparatus for recovering water from CMP wastewater containing high TOC Download PDFInfo
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本発明は、高ＴＯＣ含有ＣＭＰ排水からの水回収方法及び水回収装置に係り、特に高濃度でＴＯＣを含有するＣＭＰ（Chemical Mechanical Polishing）排水を、精密濾過（ＭＦ）膜で膜分離処理した後２段逆浸透（ＲＯ）膜分離処理することにより、有効再利用可能な水を効率的に回収する方法と装置に関する。 The present invention relates to a method and an apparatus for recovering water from high TOC-containing CMP wastewater, and in particular, after membrane separation treatment of a CMP (Chemical Mechanical Polishing) wastewater containing TOC at a high concentration with a microfiltration (MF) membrane. The present invention relates to a method and an apparatus for efficiently recovering water that can be effectively reused by performing a two-stage reverse osmosis (RO) membrane separation treatment.
半導体ウエハ及びその上に形成された絶縁膜、メタル薄膜等の被膜の表面は高度な平坦面であることが望まれる。従来、ウエハや、その上に形成された被膜の平坦化には、研磨材のスラリを用いて化学的機械研磨（ＣＭＰ）する方法が採用されている。この方法では、研磨パッド等の研磨部材と半導体ウエハとの間に研磨材スラリを介在させた状態で研磨を行い、半導体ウエハあるいはシリコン酸化膜や金属薄膜等の被膜表面を平坦化する方法である。このＣＭＰで用いられる研磨材としては、分散性が良好で、平均粒子径が揃っているシリカ微粒子（コロイダルシリカ）が一般的に使用されている。また、研磨速度の高いセリア（ＣｅＯ２）や、硬度が高く安定なアルミナ（Ａｌ２Ｏ３）等も使用されている。セリアやアルミナ等の無機酸化物は、平均粒子径が０．０５〜０．５μｍ程度の粒子が水中に分散したスラリとして使用されており、通常、このスラリ中には、ｐＨ調整剤（ＫＯＨ，ＮＨ４ＯＨ，有機酸，アミン類）や界面活性剤（分散剤）、酸化剤（Ｈ２Ｏ２，ＫＩＯ３，Ｆｅ（ＮＯ３）３）等が別途添加されて使用される。 It is desired that the surface of the semiconductor wafer and the coating film such as an insulating film and a metal thin film formed on the semiconductor wafer be a highly flat surface. Conventionally, a chemical mechanical polishing (CMP) method using a slurry of an abrasive material has been employed to planarize a wafer and a film formed thereon. In this method, polishing is performed in a state where an abrasive slurry is interposed between a polishing member such as a polishing pad and a semiconductor wafer, and the surface of the film such as a semiconductor wafer or a silicon oxide film or a metal thin film is flattened. . As an abrasive used in this CMP, silica fine particles (colloidal silica) having good dispersibility and uniform average particle diameter are generally used. Further, ceria (CeO 2 ) having a high polishing rate, alumina having a high hardness and stability (Al 2 O 3 ), and the like are also used. Inorganic oxides such as ceria and alumina are used as a slurry in which particles having an average particle size of about 0.05 to 0.5 μm are dispersed in water. Usually, a pH adjuster (KOH, NH 4 OH, organic acids, amines), a surfactant (dispersing agent), an oxidizing agent (H 2 O 2 , KIO 3 , Fe (NO 3 ) 3 ) and the like are separately added and used.
この研磨材スラリは、１枚のウエハ当りの使用量が多く、しかも非常に高価であることから、ウエハのＣＭＰ工程から排出される排スラリから研磨材を回収し、回収した研磨材を用いて所定の組成の研磨材スラリを調整すると共に、分離水を処理して再利用することが望まれる。 Since this abrasive slurry has a large amount of use per wafer and is very expensive, the abrasive is recovered from the exhaust slurry discharged from the CMP process of the wafer, and the recovered abrasive is used. It is desired to adjust the abrasive slurry having a predetermined composition and to treat and reuse the separated water.
従来、ＣＭＰ工程から排出される排スラリから研磨材を回収する方法として、ＵＦ（限外濾過）膜を用いて膜分離処理を行う方法が提案されている（例えば特開平８−１１５８９２号公報）。この方法では、排スラリを精密濾過（ＵＦ）膜分離処理して粗大不純物を除去した後、ＵＦ膜分離処理して濃縮液から研磨材を回収する。また、この方法におけるＵＦ膜の目詰まりを防止するために、排スラリを界面活性剤の存在下にｐＨ６．８以下で凝集処理し、凝集処理水をＵＦ膜分離処理する方法が提案されている（特開２０００−１２６７６８号公報）。この方法では、ＵＦ膜分離処理の透過水を更にＲＯ膜分離処理して水を回収する。 2. Description of the Related Art Conventionally, as a method for recovering an abrasive from waste slurry discharged from a CMP process, a method of performing a membrane separation process using a UF (ultrafiltration) membrane has been proposed (for example, Japanese Patent Application Laid-Open No. 8-115589). . In this method, the exhaust slurry is subjected to a microfiltration (UF) membrane separation treatment to remove coarse impurities, and then the UF membrane separation treatment is performed to recover the abrasive from the concentrated liquid. In order to prevent clogging of the UF membrane in this method, a method is proposed in which the waste slurry is agglomerated at a pH of 6.8 or less in the presence of a surfactant, and the agglomerated water is subjected to a UF membrane separation treatment. (Japanese Unexamined Patent Publication No. 2000-126768). In this method, the permeated water of the UF membrane separation treatment is further subjected to RO membrane separation treatment to recover water.
ところで、ＣＭＰ排水は、そのＣＭＰ工程の種別、時期等によりその組成、濃度、性状等が異なる。しかして、研磨材として特にセリア（ＣｅＯ２）系の研磨材を用いた場合には、スラリの分散を十分に行うために、分散剤として分子量が数百程度と分子量の大きいカルボン酸が添加されると共に、ｐＨ調整のための有機アルカリ（例えば、ＴＭＡＨ：テトラメチルアンモニウムハイドライド）が添加されるため、排スラリから研磨材を分離回収した分離水として、ＴＯＣ濃度として４００〜６００ｍｇ／Ｌというような高ＴＯＣ含有ＣＭＰ排水が排出される。 By the way, the composition, concentration, property, and the like of the CMP waste water differ depending on the type and timing of the CMP process. Thus, particularly when a ceria (CeO 2 ) -based abrasive is used as an abrasive, a carboxylic acid having a molecular weight of about several hundreds and a large molecular weight is added as a dispersant in order to sufficiently disperse the slurry. In addition, since an organic alkali (for example, TMAH: tetramethylammonium hydride) for pH adjustment is added, the TOC concentration is 400 to 600 mg / L as separated water obtained by separating and recovering the abrasive from the waste slurry. High TOC content CMP waste water is discharged.
従来、このようなＴＯＣ濃度の高い水は、物理・化学的な処理では処理し得ず、水回収のためには前処理として生物処理を組み込む必要があるとされている。従って、高ＴＯＣ含有ＣＭＰ排水についても、従来は、他のフッ酸系排水と混合して凝集・沈殿処理するか、或いは、高ＴＯＣ含有ＣＭＰ排水のみで凝集・沈殿処理した後、フッ酸系排水の凝集・沈殿処理水と混合して処理された後放流されており、水回収は行われていなかった。 Conventionally, water having such a high TOC concentration cannot be treated by physical or chemical treatment, and it is said that biological treatment must be incorporated as a pretreatment for water recovery. Therefore, high TOC-containing CMP wastewater is conventionally mixed with other hydrofluoric acid-based wastewaters for coagulation / precipitation treatment, or after coagulation / precipitation treatment only with high-TOC-containing CMP wastewater, hydrofluoric acid wastewater It was discharged after being mixed with the coagulation / precipitation treated water, and no water was collected.
なお、前述の特開２０００−１２６７６８号公報の方法を、このような高ＴＯＣ含有ＣＭＰ排水に適用した場合、ｐＨ６．８以下の条件でＵＦ膜分離処理した後、ｐＨ中性のＵＦ膜分離処理の透過水をＲＯ膜分離処理することにより、ＲＯ膜面においてＴＯＣ成分の高濃縮による膜面の汚染やスライム障害（ＴＯＣ濃度が高いとそれをエサとするバクテリアが発生・増殖し、これによりスライム障害が起きる。）の問題があり、膜差圧の上昇で、膜フラックスの低下や処理水質の悪化を招く。
本発明は上記従来の問題点を解決し、高ＴＯＣ含有ＣＭＰ排水を処理して良好な水質の水を効率的に回収する方法及び装置を提供することを目的とする。 An object of the present invention is to solve the above-mentioned conventional problems and to provide a method and an apparatus for efficiently recovering water of good water quality by treating high TOC-containing CMP wastewater.
本発明の高ＴＯＣ含有ＣＭＰ排水からの水回収方法は、高ＴＯＣ含有ＣＭＰ排水を処理して水を回収する方法において、該ＣＭＰ排水を精密濾過膜で膜分離処理する精密濾過膜分離工程と、該精密濾過膜分離工程の濾過水をｐＨ１１〜１２において逆浸透膜分離処理する第１の逆浸透膜分離工程と、該第１の逆浸透膜分離工程の透過水をｐＨ６．５〜７．５において逆浸透膜分離処理する第２の逆浸透膜分離工程とを備えてなることを特徴とする。 The method for recovering water from the high TOC-containing CMP waste water of the present invention is a method for recovering water by treating the high TOC-containing CMP waste water, and a microfiltration membrane separation step of membrane-separating the CMP wastewater with a microfiltration membrane; A first reverse osmosis membrane separation process in which the filtered water in the microfiltration membrane separation step is subjected to reverse osmosis membrane separation treatment at pH 11 to 12, and the permeated water in the first reverse osmosis membrane separation step is pH 6.5 to 7.5. And a second reverse osmosis membrane separation step for performing a reverse osmosis membrane separation treatment.
本発明の高ＴＯＣ含有ＣＭＰ排水からの水回収装置は、高ＴＯＣ含有ＣＭＰ排水を処理して水を回収する装置において、該ＣＭＰ排水が導入される精密濾過膜分離手段と、該精密濾過膜分離手段の濾過水が必要に応じてｐＨ調整された後、ＰＨ１１〜１２の条件で導入される第１の逆浸透膜分離手段と、該第１の逆浸透膜分離手段の透過水をｐＨ６．５〜７．５に調整する中和手段と、該中和手段の処理水が導入される第２の逆浸透膜分離手段とを備えてなることを特徴とする。 The apparatus for recovering water from the high TOC content CMP waste water of the present invention is a device for processing the high TOC content CMP waste water to recover water, and a microfiltration membrane separation means for introducing the CMP waste water, and the microfiltration membrane separation. After the pH of the filtered water of the means is adjusted as necessary, the first reverse osmosis membrane separation means introduced under the conditions of PH 11 to 12 and the permeated water of the first reverse osmosis membrane separation means are adjusted to pH 6.5. It is characterized by comprising neutralizing means for adjusting to -7.5, and second reverse osmosis membrane separating means for introducing treated water of the neutralizing means.
本発明によれば、高ＴＯＣ含有ＣＭＰ排水をＭＦ膜分離処理した後、特定のｐＨ条件で２段ＲＯ膜分離処理することにより、膜フラックス低下、スライム障害等の問題を引き起こすことなく、簡易な操作で、長期に亘り安定な処理を行って、良好な水質の水を回収することができる。 According to the present invention, a high TOC content CMP waste water is subjected to MF membrane separation treatment, and then subjected to a two-stage RO membrane separation treatment under a specific pH condition, thereby causing simple problems without causing problems such as membrane flux reduction and slime failure. By operation, a stable treatment can be performed over a long period of time, and water with good water quality can be recovered.
即ち、本発明では、高ＴＯＣ含有ＣＭＰ排水をまずＭＦ膜分離処理することにより、濁質成分を除去し、ＭＦ膜分離処理の濾過水をｐＨ１１〜１２の高アルカリ条件で第１のＲＯ膜分離処理を行うことにより、膜フラックスの低下を防止すると共に、スライム発生を抑制して水中のＴＯＣや溶存塩類を粗取りする。その後、この第１のＲＯ膜分離処理の透過水について更にｐＨ６．５〜７．５の中性条件で第２のＲＯ膜分離処理を行うことにより、残留するＴＯＣ成分と溶存塩類を高度に除去する。この第２のＲＯ膜分離処理においては、第１のＲＯ膜分離処理において、予めＴＯＣ成分が粗取りされているため、ＴＯＣの高濃縮による膜面汚染やスライム発生の問題はなく、ＴＯＣ成分と溶存塩類の高度処理により、良好な水質の処理水を得ることができる。 That is, in the present invention, the high TOC-containing CMP wastewater is first subjected to MF membrane separation treatment to remove turbid components, and the filtered water of the MF membrane separation treatment is subjected to the first RO membrane separation under high alkaline conditions of pH 11-12. By performing the treatment, the membrane flux is prevented from being lowered, and slime generation is suppressed to roughly remove TOC and dissolved salts in water. Thereafter, the permeated water of the first RO membrane separation treatment is further subjected to a second RO membrane separation treatment under neutral conditions of pH 6.5 to 7.5, thereby highly removing residual TOC components and dissolved salts. To do. In this second RO membrane separation process, since the TOC component has been roughly removed in advance in the first RO membrane separation process, there is no problem of membrane surface contamination or slime generation due to high concentration of TOC. Treated water with good water quality can be obtained by advanced treatment of dissolved salts.
このような本発明の方法及び装置は、特にＴＯＣ濃度４００ｍｇ／Ｌ以上の高濃度ＴＯＣ含有ＣＭＰ排水の処理に好適である。 Such a method and apparatus of the present invention is particularly suitable for the treatment of high concentration TOC-containing CMP waste water having a TOC concentration of 400 mg / L or more.
以下に図面を参照して本発明の高ＴＯＣ含有ＣＭＰ排水からの水回収方法及び水回収装置の実施の形態を詳細に説明する。 Embodiments of a water recovery method and a water recovery apparatus from a high TOC-containing CMP waste water according to the present invention will be described below in detail with reference to the drawings.
図１は本発明の高ＴＯＣ含有ＣＭＰ排水からの水回収方法及び水回収装置の実施の形態を示す系統図である。 FIG. 1 is a system diagram showing an embodiment of a method and a water recovery apparatus for recovering water from a CMP wastewater containing high TOC according to the present invention.
高ＴＯＣ含有ＣＭＰ排水はまず原水貯槽１を経てポンプＰ１により循環水槽２に導入され、ポンプＰ２によりＭＦ膜分離装置３に送給されてＭＦ膜分離処理される。ＭＦ膜分離装置３の濃縮水はその一部が循環水槽２に返送されて循環処理され、残部は排水として系外に排出され、フッ素含有排水処理系統の凝集処理の入口側、或いはその後段の汚泥濃縮槽へ送給される。 High TOC content CMP wastewater is introduced into the circulation water tank 2 by the pump P 1 is first through the raw water tank 1, are fed to the MF membrane separator 3 is MF membrane separation by means of a pump P 2. A part of the concentrated water of the MF membrane separation device 3 is returned to the circulating water tank 2 and circulated, and the remaining part is discharged out of the system as waste water. It is sent to the sludge concentration tank.
本発明において、処理対象とする高ＴＯＣ含有ＣＭＰ排水は、ＴＯＣ濃度４００ｍｇ／Ｌ以上、例えば４００〜６００ｍｇ／Ｌ以上のＣＭＰ排水である。一般にこのようなＣＭＰ排水は、セリア（ＣｅＯ２）微粒子を研磨材とする研磨工程から排出されるセリア系ＣＭＰ排水である。 In the present invention, the high TOC-containing CMP wastewater to be treated is a CMP wastewater having a TOC concentration of 400 mg / L or more, for example, 400 to 600 mg / L or more. In general, such CMP waste water is ceria-based CMP waste water discharged from a polishing process using ceria (CeO 2 ) fine particles as an abrasive.
本発明に係る高ＴＯＣ含有ＣＭＰ排水は、このようなセリア微粒子を研磨材とする研磨工程等から排出される濃厚排出スラリとその後の水洗浄排水あるいは化学洗浄排水とが混合された排水である。このＣＭＰ排水、特にセリア系ＣＭＰ排水は、通常ＴＯＣ成分を４００〜６００ｍｇ／Ｌ含み、ｐＨ１１〜１２、電気伝導度５０〜１００ｍＳ／ｍ程度の排水である。このＣＭＰ排水に含まれるＴＯＣ成分は、主に研磨材スラリに分散剤として添加された高分子量のカルボン酸と、ｐＨ調整剤として添加されたＴＭＡＨ等の有機アルカリである。 The high TOC-containing CMP waste water according to the present invention is a waste water in which a thick discharge slurry discharged from such a polishing process using ceria fine particles as an abrasive and a subsequent water cleaning waste water or chemical cleaning waste water are mixed. This CMP wastewater, particularly ceria-based CMP wastewater, usually contains 400 to 600 mg / L of TOC component, and has a pH of 11 to 12 and an electrical conductivity of about 50 to 100 mS / m. The TOC component contained in this CMP waste water is mainly a high molecular weight carboxylic acid added as a dispersant to the abrasive slurry and an organic alkali such as TMAH added as a pH adjuster.
また、このような高ＴＯＣ含有ＣＭＰ排水の排出量は工場規模によっても異なるが、通常７．５〜１５ｍ３／ｈｒ程度である。 Moreover, although the discharge amount of such high TOC content CMP waste water changes with factory scales, it is about 7.5-15 m < 3 > / hr normally.
このような高ＴＯＣ含有ＣＭＰ排水が導入されるＭＦ膜分離装置３のＭＦ膜としては、孔径０．０２〜０．１μｍ程度のものが好ましい。膜の材質や型式には特に制限はなく、有機膜であっても無機膜であっても良い。 As the MF membrane of the MF membrane separation apparatus 3 into which such high TOC content CMP wastewater is introduced, those having a pore diameter of about 0.02 to 0.1 μm are preferable. The material and type of the film are not particularly limited, and may be an organic film or an inorganic film.
ＭＦ膜分離処理は、バッチ処理（所定の濃縮倍率毎に濃縮水を排出する処理）、連続処理のいずれであっても良いが、タイマー制御により定期的にＭＦ膜の逆洗を行う。 The MF membrane separation process may be either a batch process (a process for discharging concentrated water for each predetermined concentration ratio) or a continuous process, but the MF membrane is periodically back-washed by timer control.
ＭＦ膜分離処理の濃縮倍率は低過ぎると水回収率が悪くなり、高過ぎると透過流量の低下や排水循環流路閉塞などの障害が生じるため、３０〜６０倍程度とすることが好ましい。 If the concentration ratio of the MF membrane separation treatment is too low, the water recovery rate is deteriorated, and if it is too high, problems such as a decrease in the permeate flow rate and a blockage of the drain circulation path occur. Therefore, the concentration is preferably about 30 to 60 times.
このようなＭＦ膜分離処理では、ＣＭＰ排水中の濁質成分が分離除去されるが、溶解したＴＯＣ成分及び溶存塩類は除去されずそのままＭＦ膜濾過水中に移行する。従って、ＴＯＣ成分が濃縮されないため、このＭＦ膜分離装置３では、ＴＯＣ成分の高濃縮に起因する膜汚染やスライム発生の問題はない。また、ｐＨ変化なく、ＭＦ膜濾過水はＣＭＰ排水と同等のｐＨである。なお、ＭＦ膜分離処理で、表面荷電を持つ濁質が除去されることにより、ＭＦ膜濾過水の電気伝導度はＣＭＰ排水よりも２０〜３０％程度低くなる。 In such an MF membrane separation process, the turbid component in the CMP waste water is separated and removed, but the dissolved TOC component and dissolved salts are not removed but are transferred to the MF membrane filtered water as they are. Therefore, since the TOC component is not concentrated, the MF membrane separation apparatus 3 has no problem of membrane contamination or slime generation due to high concentration of the TOC component. Moreover, the MF membrane filtered water has a pH equivalent to that of the CMP waste water without changing the pH. In addition, by removing turbidity having surface charge in the MF membrane separation treatment, the electrical conductivity of the MF membrane filtrate is about 20 to 30% lower than that of the CMP waste water.
ＭＦ膜濾過水は、次いでＲＯ給水槽４を経て後段の第２ＲＯ膜分離装置６の濃縮水と共に給水ポンプＰ３及び昇圧ポンプＰ４により第１ＲＯ膜分離装置５に送給されてＲＯ膜分離処理される。 The MF membrane filtered water is then supplied to the first RO membrane separation device 5 by the feed water pump P 3 and the booster pump P 4 together with the concentrated water of the second RO membrane separation device 6 in the subsequent stage through the RO water tank 4 and the RO membrane separation treatment. Is done.
ここで、ＲＯ給水槽４及び給水ポンプＰ３は設けた方が好ましいが、ＭＦ膜濾過水の圧力が０．１５ＭＰａ以上であり、ＣＭＰ排水が連続的に供給され、ＭＦ膜濾過水も連続的に供給される場合には、ＲＯ給水槽４及び給水ポンプＰ３は省略しても良い。ＭＦ膜分離装置３がバッチ処理である場合には、ＭＦ膜濾過水の流量が変化するため、ＲＯ給水槽４及び給水ポンプＰ３が必須である。 Here, preferably who provided RO feedwater tank 4 and the water supply pump P 3, the pressure of the MF membrane filtration water is not less 0.15MPa or more, CMP wastewater is continuously fed, continuous rather MF membrane filtered water when applied to the, RO feedwater tank 4 and the water supply pump P 3 may be omitted. If MF membrane separator 3 is a batch process, the flow rate of the MF membrane filtration water is changed, RO water tank 4 and the water supply pump P 3 are essential.
本発明においては、第１ＲＯ膜分離装置５において、ＲＯ給水をｐＨ１１〜１２の条件でＲＯ膜分離処理するが、前述の如く、ＣＭＰ排水、特にセリア系ＣＭＰ排水は一般にｐＨ１１〜１２のアルカリ性排水であり、これをＭＦ膜分離処理して得られるＭＦ膜濾過水も同等のｐＨであることから、このＭＦ膜濾過水をｐＨ調整することなくそのまま第１ＲＯ膜分離処理に供することができる。 In the present invention, in the first RO membrane separation device 5, RO feed water is subjected to RO membrane separation treatment under the condition of pH 11-12. As described above, CMP wastewater, particularly ceria-based CMP wastewater is generally alkaline wastewater of pH 11-12. In addition, since the MF membrane filtrate obtained by subjecting this to the MF membrane separation treatment has the same pH, the MF membrane filtration water can be directly used for the first RO membrane separation treatment without adjusting the pH.
本発明において、この第１ＲＯ膜分離処理をｐＨ１１〜１２で行うことは極めて重要である。 In the present invention, it is extremely important to perform the first RO membrane separation treatment at pH 11-12.
即ち、この第１ＲＯ膜分離処理をｐＨ中性を行う場合には、ＲＯ膜面でのＴＯＣ成分の高濃縮のために膜面汚染、スライム発生の問題が有り、膜差圧の上昇、膜フラックスの低下、処理水質（透過水水質）低下の問題を引き起こす。特にｐＨ４〜９の条件では、スライムの発生は避けられない。また、ｐＨ中性にするための中和剤の添加が必要となり、このためにＲＯ給水の溶存塩類濃度が高くなり、浸透圧が高くなって低フラックス運転とならざるを得ず、処理に必要なＲＯ膜本数が多くなると共に処理水質低下などの問題が起こる。 That is, when this first RO membrane separation treatment is neutral to pH, there is a problem of membrane surface contamination and slime generation due to high concentration of TOC components on the RO membrane surface, increase in membrane differential pressure, membrane flux Cause deterioration of treated water quality (permeated water quality). In particular, generation of slime is inevitable under the condition of pH 4-9. In addition, it is necessary to add a neutralizing agent to neutralize the pH, which increases the dissolved salt concentration of the RO feedwater, which increases the osmotic pressure and requires low flux operation, which is necessary for processing. As the number of RO membranes increases, problems such as degradation of treated water occur.
第１ＲＯ膜分離装置５の給水のｐＨが１１未満では高濃縮ＴＯＣによる膜汚染やスライムの発生を防止し得ず、ｐＨ１２を超えると後段の第２ＲＯ膜分離装置６の給水のｐＨ調整のために多量の中和剤を必要とし、好ましくない。 If the pH of the feed water of the first RO membrane separation device 5 is less than 11, membrane contamination and slime generation due to highly concentrated TOC cannot be prevented. If the pH exceeds 12, the pH of the feed water of the second RO membrane separation device 6 in the subsequent stage is adjusted. A large amount of neutralizing agent is required, which is not preferable.
本発明では、ｐＨ１１〜１２でＲＯ膜分離処理するため、例えばセリア系ＣＭＰ排水であればｐＨ調整の必要がなく、高濃縮ＴＯＣによる膜面汚染や、スライムの発生、それによる膜フラックスの低下を抑制して安定かつ効率的なＲＯ膜分離処理を行うことができる。 In the present invention, since RO membrane separation treatment is performed at a pH of 11 to 12, there is no need for pH adjustment, for example, in the case of ceria-based CMP wastewater, and membrane surface contamination due to highly concentrated TOC, generation of slime, resulting in a decrease in membrane flux. Stable and efficient RO membrane separation treatment can be performed.
第１ＲＯ膜分離装置５のＲＯ膜としては、ｐＨ１１〜１２の耐アルカリ性を有するものであれば良く、特に制限はないが、例えば、低圧、超低圧のポリアミド複合膜が好適に用いられる。 The RO membrane of the first RO membrane separation device 5 is not particularly limited as long as it has alkali resistance of pH 11 to 12, and for example, a low-pressure, ultra-low pressure polyamide composite membrane is preferably used.
この第１ＲＯ膜分離装置５の水回収率は、６０〜８０％程度とすることが好ましい。 The water recovery rate of the first RO membrane separation device 5 is preferably about 60 to 80%.
第１ＲＯ膜分離装置５の透過水は、第１ＲＯ膜分離装置５でＴＯＣ成分の９０〜９６％及び溶存塩類の８０％以上が除去された水であり、通常そのｐＨは第１ＲＯ膜分離装置５の給水より０．２〜０．５程度低い、ｐＨ１０．５〜１０．９程度のアルカリ性である。 The permeated water of the first RO membrane separation device 5 is water from which 90 to 96% of the TOC component and 80% or more of the dissolved salts have been removed by the first RO membrane separation device 5, and usually the pH thereof is the first RO membrane separation device 5. It is alkaline with a pH of about 10.5 to 10.9, which is about 0.2 to 0.5 lower than the feed water.
この第１ＲＯ膜透過水は、次いで塩酸（ＨＣｌ）等の酸を添加してｐＨ６．５〜７．５に調整した後、第２ＲＯ膜分離装置６でＲＯ膜分離処理する。第２ＲＯ膜分離装置６の給水のｐＨが６．５未満では第２ＲＯ膜透過水への酸リークとこれによる処理水電気伝導度上昇が生じ、７．５を超えると逆に第２ＲＯ膜透過水へのアルカリリークによる処理水電気伝導度上昇が生じ、水回収しても再利用が難しくなる。 This first RO membrane permeated water is then adjusted to pH 6.5 to 7.5 by adding an acid such as hydrochloric acid (HCl) and then subjected to RO membrane separation treatment by the second RO membrane separation device 6. If the pH of the feed water of the second RO membrane separation device 6 is less than 6.5, an acid leak to the second RO membrane permeate and an increase in the electrical conductivity of the treated water occur, and if it exceeds 7.5, the second RO membrane permeate The electrical conductivity of the treated water is increased due to alkali leak, and it is difficult to reuse even if water is recovered.
なお、第１ＲＯ膜分離装置５の濃縮水は高濃度ＴＯＣ成分と溶存塩類とを含む水であり、系外へ排出され、他の有機系排水と合流して処理されるが、単独で蒸発濃縮され、処分される。 The concentrated water of the first RO membrane separation device 5 is water containing a high-concentration TOC component and dissolved salts, and it is discharged out of the system and combined with other organic wastewater to be treated. And disposed of.
第２ＲＯ膜分離装置６では、このような中性の給水が導入されるが、この給水は、ＭＦ膜分離装置３で濁質が除去された後、第１ＲＯ膜分離装置５で予めＣＭＰ排水中のＴＯＣ成分及び溶存塩類の大部分が除去されているため、この第２ＲＯ膜分離装置６での濃縮による膜汚染やスライム発生、スケール発生の問題はなく、２段のＲＯ膜分離処理による高度処理で高水質の処理水を得ることができる。 In the second RO membrane separation device 6, such neutral water supply is introduced. This turbidity is removed from the MF membrane separation device 3 by the MF membrane separation device 3, and then the first RO membrane separation device 5 preliminarily discharges the CMP water. Because most of the TOC components and dissolved salts are removed, there is no problem of membrane contamination, slime generation, and scale generation due to concentration in the second RO membrane separation device 6, and advanced processing by two-stage RO membrane separation processing. High-quality treated water can be obtained.
第２ＲＯ膜分離装置６のＲＯ膜としては特に制限はないが、第１ＲＯ膜分離装置５のＲＯ膜と同様の低圧、超低圧のポリアミド複合膜が好適に用いられる。 The RO membrane of the second RO membrane separation device 6 is not particularly limited, but a low-pressure and ultra-low pressure polyamide composite membrane similar to the RO membrane of the first RO membrane separation device 5 is preferably used.
この第２ＲＯ膜分離装置６における水回収率は８０〜９０％程度とすることが好ましい。 The water recovery rate in the second RO membrane separation device 6 is preferably about 80 to 90%.
第２ＲＯ膜分離装置６で得られる透過水は、第１ＲＯ膜透過水中のＴＯＣ成分及び溶存塩類が更に高度に除去されることにより、ＴＯＣ濃度１ｍｇ／Ｌ以下、電気伝導度１ｍＳ／ｍ以下でｐＨ１０以下の低純度純水である。 The permeated water obtained by the second RO membrane separation device 6 has a TOC concentration of 1 mg / L or less, an electric conductivity of 1 mS / m or less and a pH of 10 by further removing TOC components and dissolved salts in the first RO membrane permeated water. The following low-purity pure water.
この第２ＲＯ膜透過水は、処理水槽７を経てポンプＰ５により系外へ移送され、そのまま研磨材スラリの調整水として又は他の用途に使用されるか、或いは超純水の製造用原水として工水系のラインに送給される。 The first 2RO membrane permeate by the pump P 5 through the treatment water tank 7 is transferred out of the system, either directly be used to adjust or as other water uses abrasive slurry, or as the raw water for the production of ultrapure water It is sent to the industrial water line.
一方、第２ＲＯ膜分離装置６の濃縮水は、予め第１ＲＯ膜分離装置５においてＴＯＣ成分と溶存塩類の大部分が除去された第１ＲＯ膜透過水から得られる比較的清浄度の高い水であるため、ＲＯ給水槽４又は第１ＲＯ膜分離装置５の入口側に返送され、第１ＲＯ膜分離装置５の給水として再度処理される。 On the other hand, the concentrated water of the second RO membrane separation device 6 is water having a relatively high cleanliness obtained from the first RO membrane permeated water from which most of the TOC component and dissolved salts have been removed in the first RO membrane separation device 5 in advance. Therefore, it is returned to the inlet side of the RO water supply tank 4 or the first RO membrane separation device 5 and processed again as the water supply of the first RO membrane separation device 5.
以下に実施例を挙げて本発明をより具体的に説明する。 Hereinafter, the present invention will be described more specifically with reference to examples.
実施例１
図１に示す方法により、下記表１に示す水質のセリア系ＣＭＰ排水の処理を行った。
Example 1
The water quality ceria-based CMP waste water shown in Table 1 below was treated by the method shown in FIG.
各装置の仕様及び運転条件は次の通りである。
［ＭＦ膜分離装置３］
ノリタケ・アルミナ社製セラミックＭＦ膜（孔径０．１μｍ）
運転条件：６０倍濃縮 ２００Ｌ／ｍ２・ｈｒ
［第１ＲＯ膜分離装置５］
栗田工業株式会社製ポリアミドＲＯ膜「ＫＲＯＡ−２０３２」
ＭＦ膜濾過水をｐＨ無調整で処理
給水圧力：７．５ｋｇ／ｃｍ２
水回収率：８０％
［第２ＲＯ膜分離装置６］
栗田工業株式会社製ポリアミドＲＯ膜「ＫＲＯＡ−２０３２」
第１ＲＯ膜透過水にＨＣｌを添加してｐＨ７．３として処理
給水圧力：７．５ｋｇ／ｃｍ２
水回収率：９０％
The specifications and operating conditions of each device are as follows.
[MF membrane separator 3]
Noritake Alumina Ceramic MF membrane (pore size 0.1μm)
Operating conditions: 60 times concentration 200L / m 2 · hr
[First RO membrane separation device 5]
Polyamide RO membrane “KROA-2032” manufactured by Kurita Kogyo Co., Ltd.
Treatment of MF membrane filtered water without adjusting pH Supply water pressure: 7.5 kg / cm 2
Water recovery rate: 80%
[Second RO membrane separation device 6]
Polyamide RO membrane “KROA-2032” manufactured by Kurita Kogyo Co., Ltd.
Processed to pH 7.3 by adding HCl to the 1st RO membrane permeated water Feed water pressure: 7.5 kg / cm 2
Water recovery rate: 90%
この処理を４００ｈｒ継続して行ったが、いずれの膜分離装置においてもフラックス低下やスライム発生の問題はなく、安定に処理を行うことができた。
この処理における各部の水質を表１に示した。
This treatment was continued for 400 hours, but there was no problem of flux reduction or slime generation in any membrane separation apparatus, and the treatment could be performed stably.
The water quality of each part in this treatment is shown in Table 1.
表１より、本発明によれば、高ＴＯＣ含有ＣＭＰ排水を安定かつ効率的に処理して良好な水質の処理水を得ることができることが分かる。 From Table 1, it can be seen that according to the present invention, high-TOC content CMP waste water can be treated stably and efficiently to obtain treated water with good water quality.
１ 原水貯槽
２ 循環水槽
３ ＭＦ膜分離装置
４ ＲＯ給水槽
５ 第１ＲＯ膜分離装置
６ 第２ＲＯ膜分離装置
７ 処理水槽
DESCRIPTION OF SYMBOLS 1 Raw water storage tank 2 Circulating water tank 3 MF membrane separation apparatus 4 RO water supply tank 5 1st RO membrane separation apparatus 6 2nd RO membrane separation apparatus 7 Treated water tank
Claims (3)
該ＣＭＰ排水を精密濾過膜で膜分離処理する精密濾過膜分離工程と、
該精密濾過膜分離工程の濾過水をｐＨ１１〜１２において逆浸透膜分離処理する第１の逆浸透膜分離工程と、
該第１の逆浸透膜分離工程の透過水をｐＨ６．５〜７．５において逆浸透膜分離処理する第２の逆浸透膜分離工程と
を備えてなることを特徴とする高ＴＯＣ含有ＣＭＰ排水からの水回収方法。 In a method of recovering water by treating high TOC-containing CMP wastewater,
A microfiltration membrane separation step of membrane separation treatment of the CMP wastewater with a microfiltration membrane;
A first reverse osmosis membrane separation step of subjecting the filtered water of the microfiltration membrane separation step to a reverse osmosis membrane separation treatment at pH 11 to 12,
A high TOC-containing CMP wastewater comprising: a second reverse osmosis membrane separation step of performing a reverse osmosis membrane separation treatment of the permeated water of the first reverse osmosis membrane separation step at pH 6.5 to 7.5 Water recovery method.
該ＣＭＰ排水が導入される精密濾過膜分離手段と、
該精密濾過膜分離手段の濾過水が必要に応じてｐＨ調整された後、ＰＨ１１〜１２の条件で導入される第１の逆浸透膜分離手段と、
該第１の逆浸透膜分離手段の透過水をｐＨ６．５〜７．５に調整する中和手段と、
該中和手段の処理水が導入される第２の逆浸透膜分離手段と
を備えてなることを特徴とする高ＴＯＣ含有ＣＭＰ排水からの水回収装置。 In an apparatus for treating high TOC-containing CMP wastewater and recovering water,
A microfiltration membrane separation means into which the CMP waste water is introduced;
A first reverse osmosis membrane separation means introduced under the conditions of pH 11 to 12 after the pH of the filtered water of the microfiltration membrane separation means is adjusted as necessary;
Neutralizing means for adjusting the permeated water of the first reverse osmosis membrane separating means to pH 6.5 to 7.5;
An apparatus for recovering water from CMP wastewater containing high TOC, comprising: a second reverse osmosis membrane separation unit into which treated water of the neutralization unit is introduced.
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