WO2022254972A1 - Method for operating reverse osmosis membrane device - Google Patents

Method for operating reverse osmosis membrane device Download PDF

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WO2022254972A1
WO2022254972A1 PCT/JP2022/017565 JP2022017565W WO2022254972A1 WO 2022254972 A1 WO2022254972 A1 WO 2022254972A1 JP 2022017565 W JP2022017565 W JP 2022017565W WO 2022254972 A1 WO2022254972 A1 WO 2022254972A1
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water
reverse osmosis
osmosis membrane
treated
membrane device
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French (fr)
Japanese (ja)
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秀樹 後藤
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栗田工業株式会社
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/12—Controlling or regulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/58—Multistep processes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • 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
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

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  • the present invention relates to a method of operating a reverse osmosis membrane device (hereinafter sometimes referred to as an RO device), and more particularly to a method of operating the RO device by making the pH of the feed water acidic.
  • an RO device reverse osmosis membrane device
  • a method of operating an RO device is known in which silica deposition on the RO membrane surface is suppressed by making the water supply of the RO device acidic with a pH of 6 or less (Patent Document 1).
  • the precipitation limit concentration of silica is about 130 mg/L, and the precipitation limit concentration rises gently as the water temperature rises.
  • Patent Document 1 states that the pH of feed water is preferably 4.0 to 5.5.
  • silica will precipitate in the RO device and in the water flow line after a period of time longer than the gelation time. of the RO device during operation is impaired.
  • An object of the present invention is to provide a method for operating a reverse osmosis membrane apparatus that suppresses silica deposition during operation stoppage and enables stable operation of the reverse osmosis membrane apparatus after operation is restarted.
  • a method of operating an RO apparatus of the present invention includes a treatment step of passing water to be treated to be acidified to pH 6 or less by adding acid to a reverse osmosis membrane device, and stopping the flow of water to the reverse osmosis membrane device. , wherein the water in the reverse osmosis membrane device is replaced with dilute water when the stopping step lasts longer than a predetermined time.
  • This dilute water preferably has a silica concentration of less than 30 mg/L, and may be reverse osmosis membrane treated water.
  • the predetermined time is 3 hours or more.
  • the water to be treated has a pH of 4.0 to 5.5, and the dilute water is the water to be treated.
  • the water to be treated to which acid has been added is introduced into the water tank to be treated, the water to be treated in the water tank to be treated is supplied to the reverse osmosis membrane device via a high-pressure pump, and the reverse osmosis membrane A portion of the system concentrate is returned between the water tank to be treated and the high pressure pump.
  • the concentrated water of the RO device when the water to be treated is passed through the RO device, the concentrated water of the RO device has a silica concentration of 300 to 500 mg/L.
  • silica precipitation is prevented by making the RO water supply acidic is that the gelation time of silica increases.
  • the water in the reverse osmosis membrane device is replaced with diluted water.
  • silica deposition is prevented during the shutdown period, and the RO device can be operated stably during the next operation.
  • FIG. 1 is a configuration diagram of an RO system in which an operating method according to an embodiment is performed;
  • the water to be treated includes factory wastewater (there is no limitation to the type of industry), industrial water, well water, city water, and, if necessary, pretreatment such as coagulation sedimentation and membrane filtration. and the like are exemplified.
  • concentration of silica in the water to be treated is about 5-80 mg/L, particularly about 10-60 mg/L, but is not limited to this.
  • pH of the water to be treated is neutral (approximately 6.2 to 7.8).
  • the water to be treated flows through the pipe 1 into the water tank 2 to be treated.
  • An acid preferably hydrochloric acid or sulfuric acid
  • a pipe 4 for introducing replacement water is connected to the pipe 1 .
  • a pipe 4 is provided with a valve 4a. The valve 4a is closed during normal operation.
  • the water to be treated in the water tank 2 to be treated which has a pH of 6 or less, preferably 4.0 to 5.5, is supplied to the RO device 8 via the pipe 5, the high-pressure pump 6, and the pipe 7, and the permeated water is passed through the pipe 9. It is then taken out and used as water for facilities, etc.
  • the concentrated water of the RO device 8 is taken out through the pipe 10.
  • part of the concentrated water is returned to the pipe 5 through the pipe 12 having the valve 11, and the remainder is sent to the neutralization facility via a line 14 having a valve 13.
  • the opening degrees of the valves 11 and 13 the return ratio of the concentrated water to the pipe 5 is adjusted.
  • the operation of the RO device 8 is stopped for a long period of time (for example, 3 hours or more, particularly 5 hours or more), the supply of the water to be treated from the pipe 1 is stopped, the high-pressure pump 6 is stopped, and the acid addition means 3 The addition of acid is stopped, and the water tank 2 to be treated is drained.
  • the valve 4a is opened, the replacement water is allowed to flow from the pipe 4 into the pipe 1, and the water in the water tank 2 to be treated, the high pressure pump 6, the RO device 8 and each pipe 1, 5, 7, 10, 12, 14 is discharged. , neutral pH, silica-lean replacement water. Note that this replacement may be performed after a predetermined time has passed since the operation of the RO device 8 was stopped.
  • the predetermined time is a time shorter than the expected start time of silica deposition in the system, and is usually selected from 0.5 to 5 hours, especially 1 to 3 hours.
  • FIG. 1(b) is obtained by installing a first RO device 20 for RO treatment of the water to be treated in the front stage of the system in FIG. 1(a).
  • the water to be treated is passed through the first RO device 20 through the pipe 18 and the pump 19 for RO treatment, and the concentrated water is sent to the pipe 1.
  • Permeated water of the first RO device 20 is taken out through a pipe 21 and used as equipment water or the like.
  • the pipe 4 branches off from the pipe 18 .
  • Other configurations in FIG. 1(b) are the same as those in FIG. 1(a), and the same reference numerals denote the same parts.
  • the valve 4a is closed so that the water to be treated does not flow through the pipe 4.
  • the pumps 19 and 6 are stopped and the acid addition from the acid addition means 3 is stopped. Also, the valve 4 a is opened, and the water to be treated is supplied from the pipe 18 to the pipe 1 through the pipe 4 as replacement water. As a result, the acidic water existing in the piping 1, the piping after the water tank 2 to be treated, the pump, the second RO device 8, etc. is replaced with the water to be treated.
  • Example 1 In the RO system with the flow shown in FIG. 0, and water temperature of about 25°C. Hydrochloric acid was added from the adding means 3 so that the pH in the water tank 2 to be treated was 4.0 to 5.5. At this time, the valve 4a is closed.
  • the flux of the RO device 8 was 50% of the initial value 30 days after the restart of operation.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Nanotechnology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Organic Chemistry (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

Provided is a method that is for operating a reverse osmosis membrane device and that enables inhibiting deposition of silica during halting of the operation, and stable operation of the reverse osmosis membrane device after resuming the operation. This method is for operating a reverse osmosis membrane device, comprises a treatment step for passing, through a reverse osmosis membrane device 8, a to-be-treated water to which an acid has been added to have an acidic pH of 6 or less, and a halting step for halting passage of water through the reverse osmosis membrane device 8, and is characterized in that when the halting step has continued for at least a predetermined period of time, the water in the reverse osmosis membrane device 8 is replaced with dilute water.

Description

逆浸透膜装置の運転方法Method of operating a reverse osmosis membrane device
　本発明は、逆浸透膜装置（以下、ＲＯ装置ということがある。）の運転方法に係り、特にＲＯ装置の給水のｐＨを酸性にして運転する方法に関する。 The present invention relates to a method of operating a reverse osmosis membrane device (hereinafter sometimes referred to as an RO device), and more particularly to a method of operating the RO device by making the pH of the feed water acidic.
　ＲＯ装置の給水のｐＨを６以下の酸性とすることにより、ＲＯ膜面へのシリカ析出を抑制するようにしたＲＯ装置の運転方法が公知である（特許文献１）。 A method of operating an RO device is known in which silica deposition on the RO membrane surface is suppressed by making the water supply of the RO device acidic with a pH of 6 or less (Patent Document 1).
　ＲＯ装置の給水が常温（２５℃）で中性（ｐＨ７）の場合、シリカの析出限界濃度は約１３０ｍｇ／Ｌであり、水温が高くなるにつれて析出限界濃度は緩やかに上昇する。 When the feed water of the RO device is normal temperature (25°C) and neutral (pH 7), the precipitation limit concentration of silica is about 130 mg/L, and the precipitation limit concentration rises gently as the water temperature rises.
　これに対し、水温が１８℃以下になると限界値が急激に低下する為、その分給水のｐＨを低くし、シリカの析出を防止することが必要である。 On the other hand, when the water temperature drops below 18°C, the limit value drops sharply, so it is necessary to lower the pH of the water supply accordingly to prevent silica precipitation.
　なお、給水のｐＨを低くする程、シリカの析出を抑制することができるが、ｐＨが低くなるにつれＲＯ装置の塩分除去率が低下すると共に、部材が腐食するリスクも高くなる。特許文献１では、給水ｐＨは４．０～５．５が好適であるとしている。 The lower the pH of the feed water, the more the deposition of silica can be suppressed. Patent Document 1 states that the pH of feed water is preferably 4.0 to 5.5.
特開平７－１６３９７９号公報JP-A-7-163979
　シリカの溶解度は、水のｐＨがアルカリ性になる程高くなり、ｐＨが酸性になるほどシリカ溶解度は低くなる。ＲＯ装置の給水のｐＨを酸性とすることにより、シリカのＲＯ膜面への析出が抑制されるのは、シリカの溶解性が高まるためではなく、水中に溶解しているシリカがゲル化するに至るまでのゲル化時間が長くなるためである。 The more alkaline the pH of water, the higher the solubility of silica, and the more acidic the pH, the lower the silica solubility. By making the pH of the feedwater of the RO unit acidic, the deposition of silica on the RO membrane surface is suppressed not because the solubility of silica increases, but because silica dissolved in water gels. This is because the gelation time until reaching the point becomes long.
　そのため、給水を酸性にして運転していたＲＯ装置が停止状態におかれた場合、ゲル化時間よりも長い時間が経過すると、ＲＯ装置内や通水ラインにおいてシリカが析出し、これにより、次回のＲＯ装置の運転時の安定性が損なわれる。 Therefore, when the RO device that has been operating with acidic feed water is put into a stopped state, silica will precipitate in the RO device and in the water flow line after a period of time longer than the gelation time. of the RO device during operation is impaired.
　本発明は、運転停止中におけるシリカ析出が抑制され、運転再開後に安定して逆浸透膜装置の運転を行うことができる逆浸透膜装置の運転方法を提供することを課題とする。 An object of the present invention is to provide a method for operating a reverse osmosis membrane apparatus that suppresses silica deposition during operation stoppage and enables stable operation of the reverse osmosis membrane apparatus after operation is restarted.
　本発明のＲＯ装置の運転方法は、酸を添加してｐＨ６以下の酸性とした被処理水を逆浸透膜装置に通水する処理工程と、該逆浸透膜装置への通水を停止する停止工程とを有する逆浸透膜装置の運転方法において、該停止工程が所定時間以上となる場合、逆浸透膜装置内の水を希薄水に置換することを特徴とする。この希薄水はシリカ濃度で３０ｍｇ／Ｌ未満であることが望ましく、逆浸透膜装置処理水も可とする。 A method of operating an RO apparatus of the present invention includes a treatment step of passing water to be treated to be acidified to pH 6 or less by adding acid to a reverse osmosis membrane device, and stopping the flow of water to the reverse osmosis membrane device. , wherein the water in the reverse osmosis membrane device is replaced with dilute water when the stopping step lasts longer than a predetermined time. This dilute water preferably has a silica concentration of less than 30 mg/L, and may be reverse osmosis membrane treated water.
　本発明の一態様では、前記所定時間は３時間以上である。 In one aspect of the present invention, the predetermined time is 3 hours or more.
　本発明の一態様では、前記被処理水のｐＨが４．０～５．５であり、前記希薄水が該被処理水である。 In one aspect of the present invention, the water to be treated has a pH of 4.0 to 5.5, and the dilute water is the water to be treated.
　本発明の一態様では、酸が添加された被処理水が被処理水槽に導入され、該被処理水槽内の被処理水が高圧ポンプを介して前記逆浸透膜装置に供給され、逆浸透膜装置の濃縮水の一部が該被処理水槽と高圧ポンプとの間に返送される。 In one aspect of the present invention, the water to be treated to which acid has been added is introduced into the water tank to be treated, the water to be treated in the water tank to be treated is supplied to the reverse osmosis membrane device via a high-pressure pump, and the reverse osmosis membrane A portion of the system concentrate is returned between the water tank to be treated and the high pressure pump.
　本発明の一態様では、前記被処理水をＲＯ装置に通水した時のＲＯ装置の濃縮水のシリカ濃度が３００～５００ｍｇ／Ｌである。 In one aspect of the present invention, when the water to be treated is passed through the RO device, the concentrated water of the RO device has a silica concentration of 300 to 500 mg/L.
　前述の通り、ＲＯ給水を酸性とすることによりシリカ析出が防止されるのは、シリカのゲル化時間が長くなるためである。 As mentioned above, the reason why silica precipitation is prevented by making the RO water supply acidic is that the gelation time of silica increases.
　本発明では、長時間運転停止を行う場合に、逆浸透膜装置内の水を希薄水に置換する。これにより、運転停止期間におけるシリカ析出が防止され、次回運転時に安定してＲＯ装置を稼働させることができる。 In the present invention, when the operation is stopped for a long time, the water in the reverse osmosis membrane device is replaced with diluted water. As a result, silica deposition is prevented during the shutdown period, and the RO device can be operated stably during the next operation.
実施の形態に係る運転方法が行われるＲＯシステムの構成図である。1 is a configuration diagram of an RO system in which an operating method according to an embodiment is performed; FIG.
　以下、図１を参照して実施の形態について説明する。 An embodiment will be described below with reference to FIG.
　本実施の形態において、被処理水としては、工場排水（業種に限定はない。）、工業用水、井水、市水や、必要に応じてそれらを凝集沈殿、膜濾過などの前処理を施したものなどが例示される。被処理水中のシリカ濃度は５～８０ｍｇ／Ｌ、特に１０～６０ｍｇ／Ｌ程度であるが、これに限定されない。また、この被処理水のｐＨは中性（６．２～７．８程度）である。 In the present embodiment, the water to be treated includes factory wastewater (there is no limitation to the type of industry), industrial water, well water, city water, and, if necessary, pretreatment such as coagulation sedimentation and membrane filtration. and the like are exemplified. The concentration of silica in the water to be treated is about 5-80 mg/L, particularly about 10-60 mg/L, but is not limited to this. Moreover, the pH of the water to be treated is neutral (approximately 6.2 to 7.8).
　図１（ａ）では、被処理水が配管１を介して被処理水槽２に流入する。配管１には酸（好ましくは塩酸又は硫酸）の添加手段３から酸が添加され、ｐＨが６以下、好ましくは４．０～５．５に調整される。また、配管１には、置換水の導入用の配管４が接続されている。配管４にバルブ４ａが設けられている。通常の運転中にはバルブ４ａは閉とされている。 In FIG. 1(a), the water to be treated flows through the pipe 1 into the water tank 2 to be treated. An acid (preferably hydrochloric acid or sulfuric acid) is added to the pipe 1 from the adding means 3 to adjust the pH to 6 or less, preferably 4.0 to 5.5. A pipe 4 for introducing replacement water is connected to the pipe 1 . A pipe 4 is provided with a valve 4a. The valve 4a is closed during normal operation.
　被処理水槽２内のｐＨ６以下、好ましくは４．０～５．５の被処理水は、配管５、高圧ポンプ６、配管７を介してＲＯ装置８に供給され、透過水が配管９を介して取り出され、設備用水等として利用される。 The water to be treated in the water tank 2 to be treated, which has a pH of 6 or less, preferably 4.0 to 5.5, is supplied to the RO device 8 via the pipe 5, the high-pressure pump 6, and the pipe 7, and the permeated water is passed through the pipe 9. It is then taken out and used as water for facilities, etc.
　ＲＯ装置８の濃縮水は、配管１０によって取り出される。流速不足による膜面分極を防止する目的で系外排出量を上げずに濃縮水の水量を上げたい場合、濃縮水の一部は弁１１を有する配管１２を介して配管５に返送され、残部は弁１３を有する配管１４を介して中和設備に送水される。弁１１，１３の開度を調節することにより、濃縮水の配管５への返送比が調整される。 The concentrated water of the RO device 8 is taken out through the pipe 10. When it is desired to increase the amount of concentrated water without increasing the amount of discharge from the system for the purpose of preventing membrane polarization due to insufficient flow velocity, part of the concentrated water is returned to the pipe 5 through the pipe 12 having the valve 11, and the remainder is sent to the neutralization facility via a line 14 having a valve 13. By adjusting the opening degrees of the valves 11 and 13, the return ratio of the concentrated water to the pipe 5 is adjusted.
　このようにＲＯ給水をｐＨ６以下、好ましくは４．０～５．５とすることにより、ＲＯ装置８や高圧ポンプ６及び各配管でのシリカ析出が抑制される。 By setting the pH of the RO water supply to 6 or less, preferably 4.0 to 5.5, silica deposition in the RO device 8, the high-pressure pump 6, and each pipe is suppressed.
　なお、この実施の形態では、ＲＯ装置８の濃縮水の一部を被処理水槽２ではなく配管５に返送する事が望ましい。これにより、シリカ濃度の高いＲＯ濃縮水が被処理水槽２に流入することがなく、被処理水槽２内での滞留時間が無くなる分、被処理水のゲル化が抑制される。 In addition, in this embodiment, it is desirable to return part of the concentrated water from the RO device 8 to the pipe 5 instead of the water tank 2 to be treated. As a result, the RO concentrated water having a high silica concentration does not flow into the water tank 2 to be treated, and the retention time in the water tank 2 to be treated is eliminated, thereby suppressing gelation of the water to be treated.
　ＲＯ装置８の運転を長期にわたって（例えば３時間以上、特に５時間以上）停止する場合には、配管１からの被処理水の供給を停止し、高圧ポンプ６を停止し、酸添加手段３からの酸添加を停止し、被処理水槽２の水抜きを行う。その後、バルブ４ａを開とし、配管４から置換水を配管１に流入させ、被処理水槽２、高圧ポンプ６、ＲＯ装置８及び各配管１，５，７，１０，１２，１４内の水を、中性ｐＨの、シリカ濃度が希薄な置換水に置換する。なお、この置換は、ＲＯ装置８の運転停止から所定時間経過してから行ってもよい。所定時間は、系内でのシリカ析出開始予想時間よりも短い時間であり、通常は０．５～５時間、特に１～３時間の間から選択された時間とされる。 When the operation of the RO device 8 is stopped for a long period of time (for example, 3 hours or more, particularly 5 hours or more), the supply of the water to be treated from the pipe 1 is stopped, the high-pressure pump 6 is stopped, and the acid addition means 3 The addition of acid is stopped, and the water tank 2 to be treated is drained. After that, the valve 4a is opened, the replacement water is allowed to flow from the pipe 4 into the pipe 1, and the water in the water tank 2 to be treated, the high pressure pump 6, the RO device 8 and each pipe 1, 5, 7, 10, 12, 14 is discharged. , neutral pH, silica-lean replacement water. Note that this replacement may be performed after a predetermined time has passed since the operation of the RO device 8 was stopped. The predetermined time is a time shorter than the expected start time of silica deposition in the system, and is usually selected from 0.5 to 5 hours, especially 1 to 3 hours.
　図１（ｂ）は、図１（ａ）において、システムの前段に、被処理水をＲＯ処理する第１ＲＯ装置２０を設置したものである。図１（ｂ）では、被処理水を、配管１８及びポンプ１９を介して第１ＲＯ装置２０に通水してＲＯ処理し、その濃縮水を配管１へ送水する。第１ＲＯ装置２０の透過水は、配管２１を介して取り出され、設備用水等として利用される。 FIG. 1(b) is obtained by installing a first RO device 20 for RO treatment of the water to be treated in the front stage of the system in FIG. 1(a). In FIG. 1(b), the water to be treated is passed through the first RO device 20 through the pipe 18 and the pump 19 for RO treatment, and the concentrated water is sent to the pipe 1. In FIG. Permeated water of the first RO device 20 is taken out through a pipe 21 and used as equipment water or the like.
　配管１８から前記配管４が分岐している。図１（ｂ）のその他の構成は図１（ａ）と同じであり、同一符号は同一部分を示している。第２ＲＯ装置８の運転時には、バルブ４ａを閉とし、配管４には被処理水を流さない。 The pipe 4 branches off from the pipe 18 . Other configurations in FIG. 1(b) are the same as those in FIG. 1(a), and the same reference numerals denote the same parts. During the operation of the second RO device 8, the valve 4a is closed so that the water to be treated does not flow through the pipe 4.
　第２ＲＯ装置８の運転を長期にわたって（例えば３時間以上、特に5時間以上）停止する場合に際しては、ポンプ１９，６を停止するとともに、酸添加手段３からの酸添加を停止する。また、バルブ４ａを開とし、被処理水を置換水として配管１８から配管４を介して配管１に供給する。これにより、配管１及び被処理水槽２以降の配管、ポンプ、第２ＲＯ装置８等に存在していた酸性の水が被処理水に置換される。 When the operation of the second RO device 8 is to be stopped for a long period of time (for example, 3 hours or more, especially 5 hours or more), the pumps 19 and 6 are stopped and the acid addition from the acid addition means 3 is stopped. Also, the valve 4 a is opened, and the water to be treated is supplied from the pipe 18 to the pipe 1 through the pipe 4 as replacement water. As a result, the acidic water existing in the piping 1, the piping after the water tank 2 to be treated, the pump, the second RO device 8, etc. is replaced with the water to be treated.
［実施例１］
　図１（ｂ）のフローのＲＯシステムにおいて、工業用水、井水、市水や、必要に応じてそれらを凝集沈殿、膜濾過などの前処理を施したもの及びシリカ濃度８０ｍｇ／Ｌ、ｐＨ６．０、水温約２５℃の工場排水（業種に限定はない）などを被処理水とし、ＲＯ処理した。被処理水槽２内のｐＨが４．０～５．５となるように塩酸を添加手段３から添加した。なお、このときバルブ４ａは閉とされている。 [Example 1]
In the RO system with the flow shown in FIG. 0, and water temperature of about 25°C. Hydrochloric acid was added from the adding means 3 so that the pH in the water tank 2 to be treated was 4.0 to 5.5. At this time, the valve 4a is closed.
　３０日運転した後、塩酸の添加を停止し、ポンプ１９，６を停止した。次いで、バルブ４ａを開とし、配管１８，４を介して被処理水を配管１に供給し、配管１及びそれよりも下流側の系内に存在していた酸性の水を被処理水に置換した。この状態で、１２時間運転を停止した。その後、運転を再開した。運転再開後、３０日経過した時点でのＲＯ装置８の透過水流束（フラックス）は初期値の８０％であった。 After 30 days of operation, the addition of hydrochloric acid was stopped and the pumps 19 and 6 were stopped. Next, the valve 4a is opened, the water to be treated is supplied to the pipe 1 through the pipes 18 and 4, and the acidic water present in the pipe 1 and the downstream system is replaced with the water to be treated. did. In this state, the operation was stopped for 12 hours. After that, it resumed driving. 30 days after restarting the operation, the permeate water flux (flux) of the RO device 8 was 80% of the initial value.
［比較例１］
　ポンプ１９，６を停止した後の酸性水の置換を行わなかったこと以外は実施例１と同一条件として運転、運転停止及び運転再開を行った。 [Comparative Example 1]
Operation, operation stop, and operation restart were performed under the same conditions as in Example 1, except that the acidic water was not replaced after the pumps 19 and 6 were stopped.
　運転再開後、３０日経過時点でのＲＯ装置８のフラックスは、初期値の５０％であった。 　The flux of the RO device 8 was 50% of the initial value 30 days after the restart of operation.
　この実施例及び比較例からも明らかな通り、本発明によると、運転を長時間停止しても、運転再開後のフラックス低下を防止し、安定して運転を行うことができる。 As is clear from this example and comparative example, according to the present invention, even if the operation is stopped for a long time, it is possible to prevent the decrease in flux after restarting the operation and to operate stably.
　本発明を特定の態様を用いて詳細に説明したが、本発明の意図と範囲を離れることなく様々な変更が可能であることは当業者に明らかである。
　本出願は、２０２１年６月３日付で出願された日本特許出願２０２１－０９３４８８に基づいており、その全体が引用により援用される。 Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application 2021-093488 filed on June 3, 2021, which is incorporated by reference in its entirety.
　２　被処理水槽
　８，２０　ＲＯ装置 2 Water tank to be treated 8, 20 RO device

Claims (5)

  1. 　酸を添加してｐＨ６以下の酸性とした被処理水を逆浸透膜装置に通水する処理工程と、
    　該逆浸透膜装置への通水を停止する停止工程と
    を有する逆浸透膜装置の運転方法において、
    　該停止工程が所定時間以上となる場合、逆浸透膜装置内の水を希薄水（シリカ濃度３０ｍｇ／Ｌ以下）に置換することを特徴とする逆浸透膜装置の運転方法。     A treatment step of passing the water to be treated, which has been acidified to pH 6 or less by adding an acid, through a reverse osmosis membrane device;
    A method for operating a reverse osmosis membrane device comprising a stopping step of stopping water flow through the reverse osmosis membrane device,
    A method of operating a reverse osmosis membrane device, characterized by replacing water in the reverse osmosis membrane device with dilute water (silica concentration of 30 mg/L or less) when the stopping step is longer than a predetermined time.
  2. 　前記所定時間は３時間以上であることを特徴とする請求項１の逆浸透膜装置の運転方法。 The method of operating a reverse osmosis membrane apparatus according to claim 1, wherein the predetermined time is 3 hours or more.
  3. 　前記被処理水のｐＨが６．２～７．８であり、前記希薄水が該被処理水である請求項１又は２の逆浸透膜装置の運転方法。 The method of operating a reverse osmosis membrane apparatus according to claim 1 or 2, wherein the water to be treated has a pH of 6.2 to 7.8, and the dilute water is the water to be treated.
  4. 　酸が添加された被処理水が被処理水槽に導入され、該被処理水槽内の被処理水が高圧ポンプを介して前記逆浸透膜装置に供給され、該逆浸透膜装置の濃縮水の一部が該被処理水槽と高圧ポンプとの間に返送されることを特徴とする請求項１又は２の逆浸透膜装置の運転方法。 Water to be treated to which an acid has been added is introduced into a water tank to be treated, water to be treated in the water tank to be treated is supplied to the reverse osmosis membrane device via a high-pressure pump, and part of the concentrated water of the reverse osmosis membrane device. 3. A method of operating a reverse osmosis membrane apparatus according to claim 1 or 2, wherein a part of the water is returned between the water tank to be treated and the high-pressure pump.
  5. 　前記被処理水のシリカ濃度が５～８０ｍｇ／Ｌであることを特徴とする請求項１又は２の逆浸透膜装置の運転方法。 The method of operating a reverse osmosis membrane apparatus according to claim 1 or 2, wherein the silica concentration of the water to be treated is 5 to 80 mg/L.
PCT/JP2022/017565 2021-06-03 2022-04-12 Method for operating reverse osmosis membrane device WO2022254972A1 (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05317854A (en) * 1992-05-15 1993-12-03 Mitsubishi Heavy Ind Ltd Method for preserving apparatus for desalination of seawater by reverse osmosis at the time of stopping
JPH07163979A (en) * 1993-12-16 1995-06-27 Japan Organo Co Ltd Reverse osmosis membrane treatment
WO2009128328A1 (en) * 2008-04-14 2009-10-22 栗田工業株式会社 Method of operating reverse osmosis membrane module
JP2015174030A (en) * 2014-03-14 2015-10-05 栗田工業株式会社 Method and apparatus for recovering cooling water effluent
JP2017064570A (en) * 2015-09-28 2017-04-06 オルガノ株式会社 Membrane treatment apparatus, drinking water production apparatus, membrane treatment method, and drinking water production method
JP2018176033A (en) * 2017-04-06 2018-11-15 オルガノ株式会社 Pure water producing apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05317854A (en) * 1992-05-15 1993-12-03 Mitsubishi Heavy Ind Ltd Method for preserving apparatus for desalination of seawater by reverse osmosis at the time of stopping
JPH07163979A (en) * 1993-12-16 1995-06-27 Japan Organo Co Ltd Reverse osmosis membrane treatment
WO2009128328A1 (en) * 2008-04-14 2009-10-22 栗田工業株式会社 Method of operating reverse osmosis membrane module
JP2015174030A (en) * 2014-03-14 2015-10-05 栗田工業株式会社 Method and apparatus for recovering cooling water effluent
JP2017064570A (en) * 2015-09-28 2017-04-06 オルガノ株式会社 Membrane treatment apparatus, drinking water production apparatus, membrane treatment method, and drinking water production method
JP2018176033A (en) * 2017-04-06 2018-11-15 オルガノ株式会社 Pure water producing apparatus

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