Treatment system and method for tetraalkylammonium hydroxide-containing liquid

Abstract

To provide a system and a method for treating a tetraalkylammonium hydroxide-containing liquid that make it possible, through reduction of concentration load for an evaporator and without installing an additional evaporator, to treat the tetraalkylammonium hydroxide-containing liquid even when the amount of the liquid increases.SOLUTION: A system for treating tetraalkylammonium hydroxide-containing liquid includes: a high-pressure reverse osmosis membrane device that concentrates a to-be-treated liquid containing tetraalkylammonium hydroxide on the concentration side; and a line that feeds the treated liquid concentrated by the reverse osmosis membrane device to an evaporator that further concentrates the liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a system and method for treating a tetraalkylammonium hydroxide-containing liquid. [Background technology]

[0002] In the photolithography process used in the manufacturing of semiconductor devices, liquid crystal displays, and other semiconductor devices, positive photoresists (hereinafter simply referred to as resists) are primarily used. The developer used is often a solution containing tetraalkylammonium hydroxide (TAAH) (TAAH developer). Tetramethylammonium hydroxide (TMAH) is commonly used as the TAAH. TMAH developer is used by applying resist to a substrate to form a resist film, and then exposing the resist film through a photomask to create alkaline solution-soluble resist areas. This is then dissolved and removed (development process) in a highly alkaline TMAH developer to create a resist pattern. Generally, a TMAH aqueous solution with a TMAH concentration of 2.38% by mass is used as the TMAH developer. In the case of positive resist, the development process increases the solubility of the exposed areas in the TMAH developer, making them soluble and removing them, while the unexposed areas of the resist remain as a resist pattern. The TMAH developer that reacted with the resist on the substrate is then washed away with pure water or other liquids. As a result, the developer waste is a mixture of the TMAH developer, dissolved resist, and water.

[0003] Because TMAH is designated as a toxic substance, wastewater treatment is essential, and factories are taking steps to address this issue. Thus, the demand for and importance of treating photoresist-containing developer wastewater (hereinafter referred to as developer wastewater) containing TMAH is increasing. Some factories use evaporators to concentrate and reduce the volume of the developer wastewater, and then treat it as industrial waste or sell it externally as a valuable resource. Furthermore, TMAH is also recovered and reused through biological treatment or treatment using electrodialysis (ED) and resins (e.g., ion exchange resins). Other known technologies include a technique for concentrating TMAH-containing wastewater by pressurizing it and feeding it through a reverse osmosis (RO) membrane (see Patent Document 1), and a technique for treating photoresist development wastewater containing photoresist and TMAH using a nanofilter (NF) membrane to separate the photoresist into a concentrated solution and the TMAH into a permeated solution (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 118282 / 1982 [Patent Document 2] Japanese Patent Application Publication No. 11-192481 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, the amount of TAAH wastewater being treated has increased due to factors such as an increase in the number of development processes and the need to treat even trace amounts of TAAH in wastewater, resulting in an increase in the amount of TAAH wastewater being concentrated using evaporators.As a result, the concentration capacity of existing evaporators is insufficient, and measures to address this issue are required. When using a separation membrane to concentrate waste developer solutions such as TAAH-containing solutions, clogging of the membrane with resist becomes a problem, and if clogging occurs, the membrane must be replaced with a new one. In recent years, high-rejection RO membranes (high-pressure RO membranes, etc.) have been released onto the market, making it possible to treat TAAH and resist with high rejection. However, with high-pressure RO membranes, membrane blockage by resist becomes a greater problem than with conventional RO (medium-pressure to ultra-low-pressure RO) membranes.

[0006] An object of the present invention is to provide a system and method for treating a TAAH-containing liquid that can treat a TAAH-containing liquid without adding an evaporator, even if the amount of TAAH-containing liquid increases, by reducing the concentration load on the evaporator. Another object of the present invention is to provide a system and method for treating a TAAH-containing liquid that can recover an RO membrane, used as a means for reducing the concentration load on the evaporator, from a state of reduced processing capacity or an inability to process due to clogging caused by resist dissolved in a developer. [Means for solving the problem]

[0007] The above-mentioned problems of the present invention have been solved by the following means. [1] A treatment system for a tetraalkylammonium hydroxide-containing liquid, comprising a high-pressure reverse osmosis membrane device that concentrates the treated liquid containing tetraalkylammonium hydroxide on the concentrating side, and a line that supplies the treated liquid concentrated by the reverse osmosis membrane device to an evaporator that further concentrates the treated liquid. [2] The system for treating a tetraalkylammonium hydroxide-containing liquid according to [1], which has a cleaning system that cleans the reverse osmosis membrane device with a cleaning liquid containing tetraalkylammonium hydroxide. [3] The treatment system for a tetraalkylammonium hydroxide-containing liquid according to [1] or [2] above can be configured such that part of the treatment system is a circulation system including the reverse osmosis membrane device, and by circulating a cleaning solution containing tetraalkylammonium hydroxide through the circulation system, the circulation system can be used as a cleaning system for cleaning the reverse osmosis membrane of the reverse osmosis membrane device. [4] The treatment system for the tetraalkylammonium hydroxide-containing liquid comprises: (a-1) a liquid tank for storing a tetraalkylammonium hydroxide-containing liquid; (b-1) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-1) a reverse osmosis membrane device to which the other end of the liquid supply pipe is connected; (d-1) a concentrated water pipe connected to the concentration side of the reverse osmosis membrane device at one end and supplying concentrated water from the reverse osmosis membrane device to an evaporator; (e-1) a concentrated water return pipe connected to the concentrated water pipe and supplying the concentrated water of the reverse osmosis membrane device to the liquid tank; (f-1) a permeate pipe having one end connected to the permeation side of the reverse osmosis membrane device; (g-1) a dilute tetraalkylammonium hydroxide wastewater treatment facility connected to the other end of the permeate piping; (h-1) a permeate return pipe connected to the permeate pipe and supplying the permeate from the reverse osmosis membrane device to the liquid tank; and The cleaning system is a system for treating a tetraalkylammonium hydroxide-containing liquid according to [3], wherein the cleaning system supplies a new tetraalkylammonium hydroxide liquid to the liquid tank and circulates the new tetraalkylammonium hydroxide liquid through both a circulation system formed by the steps (a-1) to (d-1) and (e-1) and a circulation system formed by the steps (a-1) to (c-1), (f-1) and (h-1), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device. [5] The treatment system for the tetraalkylammonium hydroxide-containing liquid comprises: (a-2) a liquid tank for storing a tetraalkylammonium hydroxide-containing liquid; (b-2) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-2) a reverse osmosis membrane device connected to the other end of the liquid supply pipe; (d-2) a concentrated water pipe connected to the concentration side of the reverse osmosis membrane device at one end and supplying the concentrated water of the reverse osmosis membrane device to an evaporator; (e-2) a concentrated water return pipe connected to the concentrated water pipe and supplying the concentrated water of the reverse osmosis membrane device to the liquid tank; (f-2) a permeate pipe connected at one end to the permeation side of the reverse osmosis membrane device; (g-2) a permeated water tank disposed midway through the permeated water piping; (h-2) a dilute tetraalkylammonium hydroxide wastewater treatment facility connected to the other end of the permeate piping; (i-2) a permeate return pipe connected to the permeate pipe located between the permeate tank and the dilute tetraalkylammonium hydroxide wastewater treatment facility, for supplying the permeate from the reverse osmosis membrane device to the liquid tank; and The cleaning system is a system for treating a tetraalkylammonium hydroxide-containing liquid according to [3], which supplies a new tetraalkylammonium hydroxide liquid to the liquid tank and circulates the new tetraalkylammonium hydroxide liquid through both a circulation system formed by the steps (a-2) to (d-2) and (e-2) and a circulation system formed by the steps (a-2) to (c-2), (f-2), (g-2) and (i-2), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device. [6] The treatment system for the tetraalkylammonium hydroxide-containing liquid comprises: (a-3) a liquid tank for storing a tetraalkylammonium hydroxide-containing liquid; (b-3) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-3) a reverse osmosis membrane device (Y) connected to the other end of the liquid supply pipe; (d-3) a concentrated water pipe connected to the concentration side of the reverse osmosis membrane device at one end and supplying the concentrated water of the reverse osmosis membrane device to an evaporator; (e-3) a concentrated water return pipe connected to the concentrated water pipe and supplying concentrated water to the reverse osmosis membrane device (Y); (f-3) a permeate pipe (P) having one end connected to the permeation side of the reverse osmosis membrane device (Y); (g-3) a permeated water tank disposed midway through the permeated water piping (P); (h-3) a dilute tetraalkylammonium hydroxide wastewater treatment facility connected to the other end of the permeate piping (P); (i-3) a permeate return pipe (I) connected to the permeate pipe (P) located between the reverse osmosis membrane device (Y) and the permeate tank, for supplying the permeate from the reverse osmosis membrane device (Y) to the liquid tank; (j-3) a permeate concentration tank disposed midway through the permeate return pipe (I); (k-3) another permeate return pipe (II) branching from the permeate pipe (P) located between the permeate tank and the diluted tetraalkylammonium hydroxide wastewater treatment facility and connected to the permeate return pipe (I) located between the reverse osmosis membrane device (Y) and the permeate concentration tank; (l-3) another reverse osmosis membrane device (Z) arranged in the middle of the other permeate return pipe (II); (m-3) another permeate piping (Q) connecting the permeation side of the other reverse osmosis membrane device (Z) to the dilute tetraalkylammonium hydroxide wastewater treatment facility, The cleaning system is a system for treating a tetraalkylammonium hydroxide-containing liquid according to [3], in which concentrated water (X) obtained by concentrating permeate from the reverse osmosis membrane device (Y) in the other reverse osmosis membrane device (Z) is supplied to the liquid tank, and the concentrated water (X) is circulated through both a circulation system formed by the (a-3) to (d-3) and (e-3) and a circulation system formed by the (a-3) to (c-3), (f-3), (i-3) and (j-3), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device. [7] The treatment system for the tetraalkylammonium hydroxide-containing liquid comprises: (a-4) a liquid tank for storing a tetraalkylammonium hydroxide-containing liquid; (b-4) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-4) a reverse osmosis membrane device connected to the other end of the liquid supply pipe; (d-4) a concentrated water pipe connected to the concentration side of the reverse osmosis membrane device at one end and supplying the concentrated water of the reverse osmosis membrane device to an evaporator; (e-4) a concentrated water tank arranged in the middle of the concentrated water piping; (f-4) a concentrated water return pipe connected to the concentrated water pipe located between the reverse osmosis membrane device and the concentrated water tank, for supplying the concentrated water from the reverse osmosis membrane device to the liquid tank; (g-4) a concentrated water permeation pipe branching from the concentrated water pipe located downstream of the concentrated water tank and connected to the concentrated water return pipe; (h-4) a nanofilter device disposed in the middle of the concentrated water permeation piping; (i-4) a nanofilter permeated water tank arranged in the middle of the concentrated water permeation piping and storing the permeated water of the nanofilter device; (j-4) a nanofilter concentrate pipe connected to the concentrate side of the nanofilter device at one end and supplying the concentrate from the nanofilter device to the evaporator; (k-4) a permeate pipe having one end connected to the permeation side of the reverse osmosis membrane device; (l-4) a dilute tetraalkylammonium hydroxide wastewater treatment facility connected to the other end of the permeate piping; (m-4) a permeate return pipe connected to the permeate pipe and supplying permeate to the liquid tank; and The cleaning system is a system for treating a tetraalkylammonium hydroxide-containing liquid according to [3], in which a new tetraalkylammonium hydroxide liquid is supplied to the liquid tank, and the new tetraalkylammonium hydroxide liquid is circulated through both a circulation system formed by the steps (a-4) to (e-4) and (f-4) to (i-4), and a circulation system formed by the steps (a-4) to (c-4), (k-4) and (m-4), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device. [8] The treatment system for the tetraalkylammonium hydroxide-containing liquid comprises: (a-5) a liquid tank for storing a tetraalkylammonium hydroxide-containing liquid; (b-5) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-5) a reverse osmosis membrane device (Y) connected to the other end of the liquid supply pipe; (d-5) a concentrated water pipe connected to the concentration side of the reverse osmosis membrane device at one end and supplying the concentrated water of the reverse osmosis membrane device to an evaporator; (e-5) a concentrated water return pipe connected to the concentrated water pipe and supplying concentrated water to the liquid tank; (f-5) a permeate pipe (P) having one end connected to the permeation side of the reverse osmosis membrane device (Y); (g-5) a permeated water tank disposed midway through the permeated water piping (P); (h-5) a diluted tetraalkylammonium hydroxide wastewater treatment facility disposed at the other end of the permeate piping (P); (i-5) a permeate return pipe (I) connected to the permeate pipe (P) located between the reverse osmosis membrane device (Y) and the permeate tank, for supplying the permeate from the reverse osmosis membrane device (Y) to the liquid tank; (j-5) a permeate concentration tank disposed midway through the permeate return pipe (I); (k-5) another permeate return pipe (II) branching from the permeate pipe (P) located between the permeate tank and the diluted tetraalkylammonium hydroxide wastewater treatment facility and connected to the permeate return pipe (I) located between the reverse osmosis membrane device (Y) and the permeate concentration tank; (l-5) another reverse osmosis membrane device (Z) arranged in the middle of the other permeate return pipe (II); (m-5) a nanofilter device disposed in the other permeate return pipe (II) and treating the concentrated water of the other reverse osmosis membrane device (Z); (n-5) another permeate piping (Q) connecting the permeation side of the other reverse osmosis membrane device (Z) to the dilute tetraalkylammonium hydroxide wastewater treatment facility; (o-5) a nanofilter concentrate pipe that connects the concentrate side of the nanofilter device to the separate permeate pipe (Q), The cleaning system is a system for treating a tetraalkylammonium hydroxide-containing liquid according to [3], in which the permeate from the reverse osmosis membrane device (Y) is concentrated in the other reverse osmosis membrane device (Z) and then supplied to the liquid tank as treated permeate that has been passed through the nanofilter device, and the treated permeate is circulated through both a circulation system formed by (a-5) to (d-5) and (e-5) and a circulation system formed by (a-5) to (c-5), (f-5) and (i-5), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device. [9] a means for measuring a resist concentration of the cleaning liquid supplied from the liquid tank by the cleaning system; The system for treating a tetraalkylammonium hydroxide-containing liquid according to any one of [4] to [8], further comprising a cleaning state detection means for detecting a cleaning state from the measured resist concentration.

[10] A method for treating a tetraalkylammonium hydroxide-containing liquid, comprising: When concentrating the liquid to be treated containing tetraalkylammonium hydroxide using an evaporator, a concentrating step of concentrating the liquid to be treated to a concentrated side using a reverse osmosis membrane device disposed upstream of the evaporator; The method for treating a tetraalkylammonium hydroxide-containing liquid includes a cleaning step of cleaning the reverse osmosis membrane of the reverse osmosis membrane device using a fresh tetraalkylammonium hydroxide solution and / or permeated water produced from the reverse osmosis membrane device in response to clogging of the reverse osmosis membrane of the reverse osmosis membrane device. [Effects of the Invention]

[0008] According to the system and method for treating a TAAH-containing liquid of the present invention, an RO membrane device is provided as a pre-concentration means upstream of the evaporator, thereby reducing the concentration load on the evaporator. This allows for the concentration of a larger amount of TAAH-containing liquid than ever before to be achieved using an existing evaporator, without the need to install an additional evaporator. Furthermore, by cleaning the photoresist clogging that occurs on the water supply side of the RO membrane serving as a pre-concentration means with fresh TAAH solution and / or the permeate obtained by treating the liquid to be treated with the reverse osmosis membrane device, it is possible to efficiently and inexpensively recover from a state in which treatment capacity has decreased or treatment is impossible due to clogging.

[0009] The above and other features and advantages of the present invention will become more apparent from the following description and accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a schematic diagram showing a preferred embodiment (first embodiment) of a system for treating a TAAH-containing liquid according to the present invention. [Figure 2] FIG. 2 is a mass balance diagram showing a preferred example of the mass balance during processing of a TAAH-containing liquid (developer waste liquid) in the processing system for a TAAH-containing liquid of the first embodiment. [Figure 3] FIG. 1 is a graph showing the relationship between the permeation flux and the operating pressure and the elapsed time for treating a TAAH-containing solution (developer waste solution) with or without a washing step. [Figure 4] FIG. 1 is a graph showing the relationship between the TMAH concentration and the cleaning time in the cleaning process. [Figure 5] FIG. 10 is a graph showing the relationship between the Na concentration and the cleaning time in the pure water cleaning step. [Figure 6] FIG. 1 is a schematic diagram showing a preferred embodiment (Embodiment 2) of a system for treating a TAAH-containing liquid according to the present invention. [Figure 7] FIG. 1 is a schematic diagram showing a preferred embodiment (Embodiment 3) of a system for treating a TAAH-containing liquid according to the present invention. [Figure 8] FIG. 1 is a schematic diagram showing a preferred embodiment (fourth embodiment) of a system for treating a TAAH-containing liquid according to the present invention. [Figure 9] FIG. 1 is a schematic diagram showing a preferred embodiment (Embodiment 3) of a system for treating a TAAH-containing liquid according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] As a system for treating a TAAH-containing liquid according to the present invention, a preferred embodiment (Embodiment 1) of a system for treating a developer waste liquid will be described below with reference to FIG. As shown in FIG. 1, a development waste liquid treatment system 1 (1A) includes a line supplying a liquid to be treated, which is development waste liquid generated in a photoresist process, to an evaporator 11 that concentrates the liquid to be treated. The liquid to be treated contains TAAH and photoresist. In the following description with reference to FIGS. 1 to 9, the liquid to be treated will be described as containing TMAH as TAAH and photoresist as an example. However, the same applies to a liquid to be treated that contains a TAAH other than TMAH. Furthermore, photoresist includes resists exposed to energy beams such as electron beams and X-rays in addition to resists exposed to light. A high-pressure reverse osmosis membrane (RO membrane) device 21 that concentrates the liquid not to be treated is provided upstream of the evaporator 11. The concentrated water produced by this RO membrane device 21 is preferably concentrated by the evaporator 11.

[0012] Specifically, the system has a liquid tank 31 that stores (reserves) untreated liquid used in the manufacturing process of semiconductor devices, etc. The liquid discharge side of the liquid tank 31 is connected to the RO membrane device 21 via a liquid supply pipe 32 that supplies the liquid to be treated. One end of the liquid supply pipe 32 is connected to the liquid discharge side of the liquid tank 31, and the other end of the liquid supply pipe 32 is connected to the water supply side 21S of the RO membrane device 21. The liquid supply pipe 32 is preferably provided with a liquid transfer means 33 that transfers the liquid in the pipe to the RO membrane device 21 side. The liquid transfer means 33 may be any means that transfers liquid, and a normal pump can be used, for example, a pressure pump. In this manner, the treated liquid supply system 30 is configured. This treated liquid supply system 30 also serves as a cleaning liquid supply system 30A, which will be described later.

[0013] The evaporator 11 is connected to the concentration side 21C (concentrated water discharge side) of the RO membrane device 21 via a concentrated water pipe 41. Specifically, one end of the concentrated water pipe 41 is connected to the concentration side 21C of the RO membrane device 21, and the other end of the concentrated water pipe 41 is connected to the supply side of the evaporator 11. In other words, the concentrated water pipe 41 is provided as a line for supplying concentrated water concentrated by the RO membrane device 21 to the evaporator 11. A concentrated water tank 42 for temporarily storing concentrated water is preferably provided midway along the concentrated water pipe 41. Furthermore, a concentrated water transfer means 43 for transferring the concentrated water in the concentrated water tank 42 to the supply side of the evaporator 11 is preferably provided in the concentrated water pipe 41 between the concentrated water tank 42 and the evaporator 11.

[0014] Meanwhile, a concentrated water return pipe 46 that supplies concentrated water to the liquid tank 31 is connected to the concentrated water pipe 41 between the RO membrane device 21 and the concentrated water tank 42. A cooler 91 is preferably provided in the concentrated water return pipe 46. This cooler 91 cools the liquid to be treated that has been heated by the liquid transfer means 33. This prevents the temperature of the liquid stored in the liquid tank 31 from becoming too high. The cooler 91 may be water-cooled or may use another refrigerant. It is sufficient if the temperature of the concentrated water can be cooled to preferably room temperature (20°C ± 15°C (JIS Z8703)), more preferably approximately 15 to 25°C. The concentrated water return pipe 46 preferably has a valve 47 near the branch point from the concentrated water pipe 41. Furthermore, the concentrated water pipe 41 preferably has a valve 48 between this branch point and the concentrated water tank 42. When treating the liquid to be treated, the valves 47 and 48 are opened with their openings adjusted. On the other hand, when cleaning, the valve 47 is opened and the valve 48 is closed. In this way, a concentrated water return system 40 (40A) (concentration side circulation system) is formed, which runs from the liquid tank 31 through the cleaning liquid supply system 30A, the concentrated side 21C of the RO membrane device 21, the concentrated water piping 41, and the concentrated water return piping 46 and returns to the liquid tank 31.

[0015] One end of a permeate pipe 61 is connected to the permeate side 21T (permeate discharge side) of the RO membrane device 21, and the other end of the permeate pipe 61 is preferably connected to a dilute TAAH wastewater treatment facility 93. The dilute TAAH wastewater treatment facility 93 is a facility that renders dilute TAAH wastewater harmless through biological treatment, adsorption detoxification, or the like. A permeate tank 62 is preferably disposed midway along the permeate pipe 61, and further, a permeate transfer means 63 for transferring the permeate in the permeate tank 62 is preferably disposed in the permeate pipe 61 between the permeate tank 62 and the dilute TAAH wastewater treatment facility 93. The permeate transfer means 63 may be any means that can deliver liquid, and a conventional pump can be used; for example, a pressure pump is preferably used. Furthermore, the permeate piping 61 can be left unconnected to the dilute TAAH wastewater treatment facility 93, and the liquid flowing through the permeate piping 61 can be reused in the semiconductor manufacturing process. Furthermore, the liquid that has been rendered harmless by the dilute TAAH wastewater treatment facility 93 can be reused in the semiconductor manufacturing process.

[0016] Meanwhile, a permeate return pipe 66 that supplies permeate to the liquid tank 31 is connected to the permeate pipe 61 between the RO membrane device 21 and the permeate tank 62. The permeate return pipe 66 preferably has a valve 67 near the branch point from the permeate pipe 61. The permeate pipe 61 also preferably has a valve 68 between this branch point and the permeate tank 62. When treating the liquid to be treated, the valve 68 is opened and the valve 67 is closed. On the other hand, when cleaning, the valve 67 is opened and the valve 68 is closed. In this way, a permeate return system 60 (60A) (permeate side circulation system) is configured, in which the liquid tank 31 returns to the liquid tank 31 through the treated liquid supply system 30A, the permeate side 21T of the RO membrane device 21, the permeate pipe 61, and the permeate return pipe 66. This is used as a cleaning system, which will be described later.

[0017] The RO membrane 21F of the RO membrane device 21 preferably has a TMAH removal rate of 99.5% by mass or more and a resist removal rate of 99.5% by mass or more. The TMAH removal rate is defined as [1 - (TMAH concentration in permeate water / TMAH concentration in feed water)] x 100%, and the resist removal rate is defined as [1 - (resist concentration in permeate water / resist concentration in feed water)] x 100%. The respective concentrations are determined by collecting samples from the sampling pipes 34, 64 on the feedwater side 21S and permeate side 21T of the RO membrane device 21, and measuring the TMAH concentration using a titration device or electrophoresis device, and the resist concentration using the absorbance readings of an absorptiometer. The RO membrane device 21 also has a mechanism for discharging water (concentrated water) in which salts and impurities are concentrated. By discharging the concentrated water, permeate water can be continuously obtained while suppressing an excessive increase in the salt concentration on the pressurized side and the formation of sparingly soluble substances (scale) on the membrane surface.

[0018] Furthermore, it is preferable that the RO membrane 21F is resistant to strong alkaline solutions such as waste developer solution (e.g., pH 12 or higher). Examples of such high-pressure RO membranes include polyamide RO membranes. Specifically, the SWC5 (product name) manufactured by Nitto Denko Corporation is one example. The manufacturer's recommended pH range for this RO membrane is 2 to 11 for normal use, and 1 to 13 during cleaning. However, even after a continuous test (3,620 hours (approximately 150 days) of continuous operation) in which a solution with a pH of approximately 12 was fed, no change in the material was observed, and it was confirmed that there were no problems with using the membrane.

[0019] The above-described waste developer treatment system 1 has an RO membrane device 21 in the upstream stage of the evaporator 11, and therefore the liquid to be treated can be concentrated by the RO membrane device 21. For example, when treating a liquid to be treated, if the TMAH concentration of the liquid to be treated is 1 mass %, the RO membrane device 21 will concentrate it three times to 3 mass %, and the evaporator 11 will further concentrate it to 25 mass %. In other words, the amount of concentrated water in the evaporator is only one-third of the conventional amount. In this way, the amount of water concentrated by the evaporator 11 is reduced, making it possible to increase the amount of liquid to be treated that can be concentrated by one evaporator 11. As a result, the amount of liquid to be treated can be increased without adding an additional evaporator 11, which requires equipment costs, and therefore the liquid to be treated can be concentrated efficiently at low cost.

[0020] When the RO membrane 21F of the RO membrane device 21 concentrates a liquid containing photoresist for a long period of time, photoresist may adhere to the water supply side 21S of the RO membrane 21F, resulting in a decrease in the amount of permeate. In such cases, a cleaning system 100 (100A) is effective for cleaning the water supply side 21S of the RO membrane 21F of the RO membrane device 21 using at least a fresh TMAH solution (a non-used solution containing TMAH) and / or permeate obtained by treating the liquid to be treated with the RO membrane device 21. That is, the cleaning system 100 can remove the resist adhered to the concentration side 21C of the RO membrane 21F. As a result, the permeation flux that decreased during the treatment of the liquid to be treated can be restored, and the decrease in the amount of permeate can be recovered. The cleaning solution preferably contains TMAH. Normally, what adheres to the water supply side of the RO membrane 21F is mainly resist dissolved by development, so by including TMAH in the cleaning solution, the resist is dissolved and easily removed.

[0021] Next, the cleaning system will be described. In the case of the waste developer treatment system 1A, the cleaning system 100A is composed of the cleaning liquid supply system 30A, which is common to the treated liquid supply system 30, the concentrated water return system 40A, and the permeated water return system 60A. The cleaning liquid supply system 30A has the same configuration as the above-mentioned treated liquid supply system 30. The concentrated water return system 40A is connected to the RO membrane device 21 and leads to the liquid tank 31, and is composed of a concentrated water piping 41 and a concentrated water return piping 46. The concentrated water piping 41 extends from the concentration side 21C of the RO membrane device 21 to the part where the concentrated water return piping 46 is connected. It is preferable to provide a cooler 91 in the concentrated water return piping 46. The permeated water return system 60A is composed of a part of the permeated water piping 61 connected to the permeate side of the RO membrane device, and a permeated water return piping 66 that branches off from the permeated water piping 61 and leads to the liquid tank 31. The permeated water piping 61 extends from the permeate side 21T of the RO membrane device 21 to the part where the permeated water return piping 66 is connected. In this way, the cleaning system 100A is a system in which the total amount of new TMAH solution supplied to the liquid tank 31 is circulated by the concentrated water return system 40A and the permeated water return system 60A, with the liquid tank 31 at the center.

[0022] Next, the measuring instruments of the developing waste liquid treatment system 1 (1A) will be described. A liquid sampling pipe 34 for sampling the liquid flowing through the pipe is preferably connected to the liquid supply pipe 32 between the transfer means 33 and the RO membrane device 21 via a valve 35. In addition, a pressure gauge 81 is preferably provided in the liquid supply pipe 32 between the liquid sampling pipe 34 and the RO membrane device 21. A concentrated water collection pipe 44 for collecting the liquid flowing through the pipe is connected to the concentrated water pipe 41 between the RO membrane device 21 and the concentrated water tank 42, and a valve 45 is preferably provided on the concentrated water collection pipe 44. A pressure gauge 82 is preferably provided on the concentrated water pipe 41 between the branch point of the concentrated water collection pipe 44 and the RO membrane device 21. A flow meter 86 is preferably provided on the concentrated water pipe 41 between the branch point of the concentrated water return pipe 46 with the concentrated water pipe 41 and the concentrated water tank 42. It is preferable that a flow meter 87 be disposed in the concentrated water return pipe 46 between the branch point of the concentrated water return pipe 46 with the concentrated water pipe 41 and the cooler 91 . A permeate collection pipe 64 for collecting the liquid flowing through the pipe is connected to the permeate pipe 61 between the RO membrane device 21 and the permeate tank 62, and a valve 65 is preferably provided on the permeate collection pipe 64. In addition, a flow meter 88 is preferably provided on the permeate pipe 61 between the permeate collection pipe 64 and the permeate tank 62.

[0023] A pH meter, a TMAH concentration meter, a resist absorbance measuring device, etc. may be connected to the liquid sampling pipe 34, the concentrated water sampling pipe 44, and the permeated water sampling pipe 64 (hereinafter also referred to as sampling pipes).

[0024] The liquid flowing through the liquid supply pipe 32, the concentrated water pipe 41, and the permeated water pipe 61 can be sampled from each of the sampling pipes 34, 44, 64 by opening the valves 35, 45, 65 disposed in the sampling pipes 34, 44, 64. Normally, the valves 35, 45, 65 are closed and are opened when sampling. Each of the pressure gauges 81, 82, and 83 may be a general pressure gauge, a digital pressure gauge, a diaphragm pressure gauge, or the like, and a diaphragm pressure gauge is preferred from the viewpoint of high alkali resistance and high pressure. For example, the SC type (product name) manufactured by Nagano Keiki Co., Ltd. may be mentioned. Each of the flow meters 86, 87, and 88 can be an area type flow meter, an impeller type flow meter, an electromagnetic type flow meter, etc., and an area type flow meter is preferred from the viewpoint of simple structure and the ability to ensure pH resistance by material. An example of such a flow meter is Purgemeter (product name) manufactured by Tokyo Keiso Co., Ltd.

[0025] The main components will be explained below. The evaporator 11 is a device that actively evaporates solids or liquids by reducing the pressure. Specifically, it is a device that facilitates the evaporation of water in wastewater by reducing the pressure inside an evaporator heated by a heat source such as steam using a vacuum pump or the like, and is generally used for reducing the volume of wastewater. For example, there is a VVCC concentrator (product name) manufactured by Sasakura Co., Ltd.

[0026] The RO membrane device 21 is not particularly limited and may be any of high-pressure, medium-pressure, low-pressure, and ultra-low-pressure RO membrane devices. However, it is preferable to use a high-pressure RO membrane having a TMAH removal rate of 99.5 mass% or more and a photoresist removal rate of 99.5 mass% or more, as described above.

[0027] The liquid tank 31 stores a photoresist-containing developer waste liquid or a cleaning liquid as the liquid to be treated. The photoresist-containing developer waste liquid is a mixture of the developer TMAH, dissolved photoresist, and water. It also includes a liquid derived from the photoresist-containing developer waste liquid. Specific examples of the liquid derived from the photoresist-containing developer waste liquid include the concentrated water produced by the RO membrane device 21 and the permeate produced by the RO membrane device 21.

[0028] In the liquid transfer means 33 that transfers the solution from the liquid tank 31 to the RO membrane device 21, at least the flow path is preferably made of an alkali-resistant material because it transfers a strongly alkaline waste developer. For example, a high-pressure pump with a flow path made of metal or an alkali-resistant material can be used. For example, a process pump (product name) manufactured by Nikuni Co., Ltd. can be used.

[0029] The concentrated water tank 42 is a tank for temporarily storing concentrated water generated by the RO membrane device 21, and may contain a liquid remaining after cleaning the RO membrane 21F using a liquid containing a developer. Therefore, it is preferable that the concentrated water tank 42 be alkali-resistant. The concentrated water tank 42 may also contain a liquid remaining after cleaning the RO membrane 21F using permeate from the RO membrane device or concentrated water from the RO membrane device.

[0030] The permeate tank 62 is a tank for temporarily storing the permeate generated by the RO membrane device 21. The permeate in the tank has an extremely low concentration of TMEH components, and the permeate in the tank can be sent directly to the diluted TAAH wastewater treatment facility 93 by operating the permeate transfer means 63.

[0031] The liquid transfer means 33 is preferably, for example, a pressure pump. Since the pressure pump transfers the liquid to be processed, which contains a strong alkaline waste developer solution, it is preferable that at least the flow path and internal parts of the pump are made of an alkali-resistant material. For example, a process pump manufactured by Nikuni Co., Ltd. can be mentioned.

[0032] The concentrated water transfer means 43 preferably uses, for example, a pressure pump similar to the liquid transfer means 33 described above.

[0033] The permeate transfer means 63 is preferably, for example, a pressure pump. Since the pressure pump transfers the permeate of the alkaline solution, it is preferable that at least the flow path and internal parts of the pump are made of alkali-resistant materials. For example, there is a Magnet Pump (product name) manufactured by Iwaki Corporation.

[0034] Next, a preferred example of a method for treating developer waste liquid using the system for treating developer waste liquid shown in FIG. 1 will be described. When treating the waste developer, the waste developer is supplied to the liquid tank 31, and the liquid transfer means 33 sends the waste developer in the liquid tank 31 to the RO membrane device 21. The permeate that has permeated the RO membrane 21F of the RO membrane device 21 is transferred to the permeate tank 62 through the permeate piping 61, and the permeate in the permeate tank 62 is preferably further sent to the dilute TAAH wastewater treatment facility 93 by the permeate transfer means 63. Meanwhile, a portion of the concentrated water produced by the RO membrane device 21 is supplied to a concentrated water tank 42 through a concentrated water pipe 41 and then sent to the evaporator 11 by a concentrated water transfer means 43 for further concentration. The remaining concentrated water is returned from the concentrated water pipe 41 to the liquid tank 31 through a concentrated water return pipe 46. The ratio of the concentrated water returned to the liquid tank 31 to the concentrated water supplied to the concentrated water tank 42 can be adjusted appropriately according to the purpose by adjusting the openings of the valves 47 and 48. Although not shown, it is preferable to adjust the flow rate to a desired value by adjusting the openings of the valves 47 and 48 while feeding back the flow rate values ​​of the flow meters 86 and 87, for example. In this way, by returning a portion of the concentrated water to the liquid tank 31, it is preferable to make the amount of water supplied to the RO membrane 21F greater than the minimum concentrated water amount for the RO membrane 21F. In this case, the liquid transfer means 33 heats the waste developer, but because it is cooled by the cooler 91, it is preferable that the concentrated water returned to the liquid tank 31 be at room temperature, for example. Normally, in the resist film development process, the developer or the pure water used as the cleaning liquid is not heated, so the waste developer is at room temperature. Therefore, because the concentrated water returned to the liquid tank 31 is cooled, the liquid temperature in the liquid tank 31 does not become too high even when the concentrated water is returned to the liquid tank 31.

[0035] For example, a specific example of a method for treating developer waste liquid will be explained using the mass balance shown in Figure 2. The following values ​​for flow rate, mass %, pH, etc. are examples and are not limited to these values. The developer waste liquid has, for example, a TMAH concentration of 0.476% by mass, a pH of 12 or higher, and a resist concentration (absorbance at a wavelength of 290 nm, optical path length of 10 mm) of 0.660. It is supplied to the liquid tank 31 as feed water (RO raw water) at a flow rate of 200 L / h. Hereinafter, the resist concentration refers to the absorbance at a wavelength of 290 nm. Furthermore, a portion of the concentrated water (circulating water) of the developer waste liquid obtained by the RO membrane device 21 (520 L / h) is mixed with the developer waste liquid to adjust the amount of water supplied to the RO membrane device 21 to 720 L / h. This increases the amount of concentrated water from the RO membrane device 21 to 600 L / h, which is greater than the minimum amount of concentrated water (e.g., 600 L / h), and the amount of permeate is increased to 120 L / h.

[0036] For example, the feed water supplied to the RO membrane device 21 has a TMAH concentration of 0.989 mass%, a pH of 12 or more, and a resist concentration of 1.347. The concentrated water from the RO membrane device 21 has a TMAH concentration of 1.185 mass%, a pH of 12 or more, and a resist concentration of 1.518. The permeate water from the RO membrane device 21 has a TMAH concentration of 0.003 mass%, a pH of 10.4 or more, and a resist concentration of 0.000. The concentrated water is not returned in its entirety to the liquid tank 31, but rather, for example, 520 L / h is returned, and the remaining 80 L / h is sent to the concentrated water tank 42 as blown concentrated water. The pH, TMAH concentration, and resist concentration in the above example are summarized in Table 1.

[0037] [Table 1]

[0038] In this way, 200 L / h of waste developer is constantly supplied, 120 L / h of permeate is discharged, and 80 L / h of concentrated water is discharged, and the remaining 520 L / h of concentrated water is returned to the liquid tank 31. Since the "developer waste liquid" is 200 L / h and the concentrated water (concentrated blow water: discharge side) sent to the concentrated water tank 42 is 80 L / h, the operating condition is 200 / 80 = 2.5 times concentrated (the resist concentration is also approximately 2.5 times concentrated). In the above case, the target concentration was 2.5 times, resulting in the mass balance shown above. It is preferable to achieve mass balance by returning a portion of the concentrated water through the concentrated water return system 40 in this way and maintaining the flow rate of the feed water supplied to the RO membrane device 21 at 720 L / h, which is equal to or greater than the minimum concentrated water volume. That is, it is preferable to balance the amounts of each liquid so as to secure the amount of water necessary for stable operation of the RO membrane device 21 and achieve the target concentration ratio. Note that the above flow rates are merely examples and are not limited to the above flow rate values.

[0039] As shown in FIG. 3, as the processing time of the developer wastewater passes, the permeation flux decreases and the operating pressure increases due to, for example, clogging of the RO membrane with resist. Therefore, it is preferable to clean the RO membrane 21F, for example, when the permeation flux and / or operating pressure reach a threshold value. Furthermore, it is also preferable to clean the RO membrane 21F, for example, when the processing time of the developer wastewater has passed a predetermined time (e.g., 1,200 hours). By performing cleaning, the permeation flux and operating pressure can be returned to their initial states. Therefore, it is preferable to clean the RO membrane 21F periodically. Depending on the specifications of the RO membrane 21F, it is preferable to clean the RO membrane 21F, for example, when the permeation flux becomes approximately 60% of the initial state (e.g., 0.4 m / d or less). Alternatively, it is preferable to clean the RO membrane 21F when the operating pressure becomes approximately 1.5 times the initial state (e.g., 1.8 MPa or more).

[0040] Next, a preferred example of a method for cleaning the RO membrane 21F of the RO membrane device 21 will be described. When cleaning the RO membrane 21F of the RO membrane device 21, all of the waste developer liquid in the RO membrane device 21 system is first discharged. At this time, the concentrated water obtained by treating the waste developer liquid in the concentrated water tank 42 and the permeated water obtained by treating the waste developer liquid in the permeated water tank 62 are also discharged, and the interiors of the liquid tank 31, RO membrane device 21, concentrated water tank 42, and permeated water tank 62, along with their respective piping, are emptied. Then, new TMAH liquid is supplied to the liquid tank 31. Next, valve 68 is closed and valve 67 is opened to open the permeated water return system 60. Also, valve 48 is closed and valve 47 is opened to open the concentrated water return system 40. In this way, the concentrated water return system 40, which runs from the liquid tank 31 through the cleaning liquid supply system 30A, the concentrated side 21C of the RO membrane device 21, the concentrated water piping 41, and the concentrated water return piping 46 and returns to the liquid tank 31, is opened. At the same time, it is preferable to open the cleaning liquid supply system 30A from the liquid tank 31, the permeate side 21T of the RO membrane device 21, the permeate piping 61, and the permeate return system 60 that returns to the liquid tank 31 through the permeate return piping 66, thereby circulating the entire amount of cleaning liquid.

[0041] Specifically, new TMAH solution is first supplied as a cleaning solution to the solution tank 31 from which the waste developer has been removed. This supply amount is preferably equal to or greater than the minimum concentrated water volume for the RO membrane 21F. The new TMAH solution can be a normal TMAH developer not used in resist film development, e.g., a TMAH developer with a TMAH concentration of 2.38% by mass. Alternatively, a TMAH developer with a higher concentration can be used. The TMAH concentration in the cleaning solution can be adjusted as needed. This new TMAH solution is sent to the RO membrane device 21 by the solution transfer means 33 to clean the water supply side of the RO membrane 21F. In this case, to ensure efficient use of the new TMAH solution and to ensure a minimum concentrated water volume for the RO membrane 21F, it is preferable to return the cleaning solution that has permeated the RO membrane device 21 to the solution tank 31. At the same time, it is preferable to return all of the concentrated water discharged from the concentration side 21C to the solution tank 31. This ensures that the amount of solution supplied to the RO membrane device 21 is equal to or greater than the minimum concentrated water volume for the RO membrane 21F.

[0042] As an example, the cleaning time is preferably 4 hours. For example, 50 L of new TMAH solution is supplied to the liquid tank 31, and then circulated using the concentrated water return system 40 and the permeated water return system 60 to return it to the liquid tank 31. At this time, the cleaning solution is circulated so as to ensure a minimum amount of concentrated water. The cleaning solution is then circulated again in the same manner. This process is preferably repeated for 4 hours. After cleaning for 4 hours using the cleaning method described above with reference to FIG. 1, the changes in the TMAH concentration in the cleaning solution and the resist concentration in the cleaning solution as supply water to the RO membrane device 21 with respect to the cleaning time are shown in Table 2 and FIG. 4. As shown in Table 2 and Figure 4, a new TMAH solution with a TMAH concentration of, for example, 2.50% by mass is used as the cleaning solution. For example, 0.25 hours after the start of cleaning, the TMAH concentration may decrease due to the inclusion of waste developer with a low TMAH concentration remaining in the system. Since the TMAH concentration in the developer is usually 2.38% by mass, the TMAH concentration in the cleaning solution may decrease. After that, the TMAH concentration becomes approximately constant and stabilizes.

[0043] It is preferable that the flow rate of the cleaning liquid immediately before the RO membrane device 21 (measured by a flow meter (not shown)) is equal to or greater than the minimum concentrated water volume of the RO membrane 21F. For example, the concentrated water is returned in its entirety to the liquid tank 31 without being sent to the concentrated water tank 42 as concentrated blow-down water. For example, 600 L / h is returned as concentrated circulating water. Furthermore, it is preferable that the entire amount of permeated water is also returned to the liquid tank 31 (the entire amount is circulated). In this way, even if the entire amounts of both the concentrated water and the permeated water are circulated, the minimum concentrated water volume of the RO membrane 21F is ensured, so there is no concern about the RO membrane 21F becoming highly concentrated.

[0044] Furthermore, the resist concentration in the cleaning liquid sampled and measured from the liquid sampling pipe 34 immediately prior to the RO membrane device 21 was 0 at the start of cleaning and increased as cleaning progressed. However, as shown in Table 2 and FIG. 4, the increase in concentration almost stopped 3 to 4 hours after the start of cleaning. The fact that the increase in resist concentration almost ceased in this way means that almost no resist removal was achieved by cleaning. In other words, this means that there was no resist left to be removed by cleaning. In other words, this indicates that cleaning was successful. Therefore, it is preferable to set the cleaning time to, for example, 4 hours. The cleaning time varies depending on the TMAH concentration of the cleaning liquid, the flow rate of the cleaning liquid, etc., but it can be said that a sufficient cleaning effect can be obtained if the cleaning is performed for 4 hours.

[0045] [Table 2]

[0046] Because the above cleaning uses fresh TMAH solution, there is no need to perform a pure water rinse after removing the developer used for cleaning. The developer waste can be disposed of immediately after the cleaning process. As shown in Table 3, for example, it takes 0.25 hours to drain the developer waste, 0.25 hours to add the cleaning solution, 4 hours for cleaning, and 0.25 hours to drain the cleaning solution, for a total cleaning time of just 4.75 hours. Alternatively, a strong alkaline sodium hydroxide solution can be used as the cleaning solution. In this case, as shown in Table 3, a pure water rinse of approximately 10 hours is required after cleaning to ensure that no sodium remains in the system. For example, it takes 0.25 hours to drain the developer waste, 0.25 hours to add the cleaning solution, 4 hours for cleaning, 0.25 hours to drain the cleaning solution, 0.25 hours to add the pure water, 10 hours for pure water rinsing, and 0.25 hours to drain the pure water cleaning solution, for a total cleaning time of 15.25 hours.

[0047] [Table 3]

[0048] In the above-mentioned pure water cleaning, it is necessary to keep the sodium concentration as close to 0% by mass as possible, for example, to 0.005% by mass or less. To achieve this, pure water cleaning for at least 10 hours is required, as shown in Table 4 and Figure 5. Even a very small amount of sodium ions, if present in the gate oxide film of a MOS transistor, for example, can cause leakage current and deteriorate the switching characteristics of the transistor. In some cases, current can flow constantly between the source and drain, causing the transistor to cease functioning. Because sodium ions thus degrade the performance of semiconductor devices, it is generally essential to remove them from the cleaning system without returning them to the semiconductor manufacturing process.

[0049] [Table 4]

[0050] When cleaning is performed using the cleaning system 100A shown in Figure 1, new TMAH solution (resist concentration 0.000) is used as the cleaning solution, so the resist concentration of the cleaning solution does not become as high as that of the developer wastewater. Because additional cleaning solution is required after the cleaning solution permeate water is discharged, the RO membrane permeate water and concentrated water of the cleaning solution are also returned to the liquid tank and reused. This ensures a sufficient cleaning flow rate for the RO membrane 21F. Furthermore, the cleaning solution concentrate is the concentrated water obtained after passing new TMAH solution through the reverse osmosis membrane device, so its resist concentration is lower than that of the concentrated water discharged during developer wastewater treatment. Therefore, the cleaning solution, which is a combination of new TMAH solution, cleaning solution permeate water, and cleaning solution concentrate, has a resist concentration of approximately 1.1, even with the addition of the cleaning solution concentrate, which is lower than that of the RO concentrate water during operation. Therefore, it is sufficiently capable of removing resist from the concentrate side surface of the reverse osmosis membrane 21F. Hereinafter, the concentrated water discharged from the concentrate side 21C after passing the cleaning solution through the RO membrane device 21 is referred to as cleaning solution concentrate.

[0051] If the concentrated water of the new TMAH solution produced by the RO membrane device 21 is not returned to the liquid tank 31, it becomes necessary to increase the supply rate of the new TMAH solution in order to ensure a sufficient amount of cleaning solution. Furthermore, during cleaning, if the concentrated cleaning solution produced from the concentration side 21C of the RO membrane device 21 is supplied to the concentrated water tank 42, the concentration of the concentrated water obtained by treating the waste developer stored in the concentrated water tank 42 will be diluted. For this reason, it is preferable to return the entire amount of the concentrated cleaning solution to the liquid tank 31. In this way, it is preferable to ensure the amount of cleaning solution supplied to the RO membrane device 21 so that the amount of concentrated water discharged is equal to or greater than the minimum amount of concentrated water from the RO membrane 21F.

[0052] As described above, the present invention provides a system for treating developer wastewater containing TAAH generated in a photolithography process, in which a part of the system including a reverse osmosis membrane device is also used as a cleaning system for cleaning the reverse osmosis membrane of the reverse osmosis membrane device. (a-1) a liquid tank for storing developer waste generated in a photolithography process; (b-1) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-1) a reverse osmosis membrane device to which the other end of the liquid supply pipe is connected and which supplies concentrated water from the reverse osmosis membrane device to an evaporator; (d-1) a concentrated water pipe having one end connected to the concentrated side of the reverse osmosis membrane device; (e-1) a concentrated water return pipe connected to the concentrated water pipe and supplying the concentrated water of the reverse osmosis membrane device to the liquid tank; (f-1) a permeate pipe having one end connected to the permeation side of the reverse osmosis membrane device; (g-1) a diluted TAAH wastewater treatment facility connected to the other end of the permeate piping; (h-1) a permeate return pipe connected to the permeate pipe and supplying the permeate of the reverse osmosis membrane device to the liquid tank; and The cleaning system supplies fresh TAAH liquid to the liquid tank and circulates the fresh TAAH liquid through both the circulation system formed by the above (a-1) to (d-1) and (e-1), and the circulation system formed by the above (a-1) to (c-1), (f-1) and (h-1), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device.

[0053] Next, a description will be given with reference to a preferred embodiment (Embodiment 2) of a treatment system 1 (1B) for a developer waste liquid as a treatment system for a TAAH-containing liquid equipped with a cleaning system 100 (100B). As shown in Figure 6, the development waste liquid treatment system 1B has the same configuration as the development waste liquid treatment system 1 (1A) described above, except that the branch position of the permeate return pipe 66 and the arrangement of the valves 67 and 68 are changed. That is, the permeate return system 60 branches off from a permeate transfer means 63 disposed in a permeate piping 61 downstream of the permeate tank 62 and supplies permeate to the liquid tank 31. The other end of the permeate transfer means 63 is connected to the permeate piping 61, which is connected to a dilute TAAH wastewater treatment facility 93. The permeate return pipe 69 preferably has a valve 70 downstream of the permeate transfer means 63. Also, the permeate pipe 61 downstream of the permeate transfer means 63 preferably has a valve 71. When treating the developer waste liquid, the valve 71 is opened and the valve 70 is closed. On the other hand, when cleaning, the valve 70 is opened and the valve 71 is closed. In this manner, a permeate return system 60 (60B) (permeate side circulation system) is configured, in which the liquid tank 31 returns to the liquid tank 31 through the cleaning liquid supply system 30B, the permeate side 21T of the RO membrane device 21, the permeate pipe 61, the permeate tank 62, and the permeate return pipe 69. The concentrated water circulation system is the same as in the first embodiment. The developer waste liquid is treated in the same way as in the developer waste liquid treatment system 1A.

[0054] In the cleaning system 100B, new TMAH is used as the cleaning liquid. The permeate that has passed through the RO membrane device 21 and is stored in the permeate tank 62 during cleaning is also used. Therefore, the resist concentration of the cleaning liquid is, for example, 0.002, which is sufficiently low. By storing the cleaning liquid permeate in the permeate tank 62 in this manner, when the cleaning liquid is insufficient, the minimum amount of concentrated water for the RO membrane device 21 can be ensured by supplying a larger amount of cleaning liquid permeate to the liquid tank 31 than the amount of permeate. Furthermore, because a sufficient flow rate of the cleaning liquid cannot be ensured using only the new TMAH liquid and the cleaning liquid permeate, the concentrated water obtained by treating the cleaning liquid with the RO membrane is also returned to the liquid tank 31 and reused. This allows the entire amount of new TMAH liquid supplied to the liquid tank 31 to be efficiently utilized, ensuring the minimum amount of concentrated water (cleaning flow rate) for the RO membrane 21F. Furthermore, because the concentrated water is the cleaning solution concentrated water obtained after the cleaning solution has passed through the RO membrane device 21, the resist concentration is significantly lower than that of the concentrated water discharged during developer wastewater treatment. Furthermore, the cleaning solution concentrated water is mixed with the new TMAH solution and the cleaning solution permeate water to form the cleaning solution, and so although it contains resist, the resist concentration is significantly lower than that of the developer wastewater. Therefore, it has sufficient ability to remove resist from the surface of the RO membrane 21F (the water supply side 21S). Hereinafter, the permeate water discharged from the permeate side 21T after passing the cleaning solution through the RO membrane device 21 will be referred to as the cleaning solution permeate water.

[0055] As described above, if the concentrated water return system 40B is not provided in the cleaning system 100B, it will be necessary to increase the amount of permeated water supplied from the permeated water tank 62 or the amount of new TMAH solution supplied in order to ensure a sufficient amount of cleaning liquid. Furthermore, when the cleaning liquid concentrate produced from the concentration side 21C is supplied to the concentrated water tank 42, the concentrate stored in the concentrated water tank 42 becomes less concentrated. For this reason, in the case of cleaning, it is preferable to return the entire amount of concentrate to the liquid tank 31. In this way, it is preferable to ensure the amount of cleaning liquid supplied to the RO membrane device 21 so that the amount of concentrated water discharged is equal to or greater than the minimum amount of concentrated water discharged from the RO membrane 21F.

[0056] The above cleaning uses permeated water obtained by treating fresh TMAH solution and waste developer solution with an RO membrane device. Therefore, there is no need to perform a pure water rinse after the cleaning, and the waste developer solution can be treated immediately after the cleaning process.

[0057] As described above, in the second embodiment of the system for treating developer waste liquid as a system for treating a TAAH-containing liquid of the present invention, the system for treating developer waste liquid is (a-2) a liquid tank for storing developer waste generated in a photolithography process; (b-2) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-2) a reverse osmosis membrane device connected to the other end of the liquid supply pipe; (d-2) a concentrated water pipe connected to the concentration side of the reverse osmosis membrane device at one end and supplying the concentrated water of the reverse osmosis membrane device to an evaporator; (e-2) a concentrated water return pipe connected to the concentrated water pipe and supplying the concentrated water of the reverse osmosis membrane device to the liquid tank; (f-2) a permeate pipe connected at one end to the permeation side of the reverse osmosis membrane device; (g-2) a permeated water tank disposed midway through the permeated water piping; (h-2) a diluted TAAH wastewater treatment facility connected to the other end of the permeate piping; (i-2) a permeate return pipe connected to the permeate pipe located between the permeate tank and the diluted TAAH wastewater treatment facility, for supplying the permeate from the reverse osmosis membrane device to the liquid tank; and The cleaning system supplies fresh TAAH liquid to the liquid tank and circulates the fresh TAAH liquid through both the circulation system formed by the above (a-2) to (d-2) and (e-2), and the circulation system formed by the above (a-2) to (c-2), (f-2), (g-2) and (i-2), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device.

[0058] Next, a description will be given with reference to a preferred embodiment (Embodiment 3) of a treatment system 1 (1C) for a developer waste liquid as a treatment system for a TAAH-containing liquid equipped with a cleaning system 100 (100C). 7, the developer waste liquid treatment system 1C is mainly configured by combining the above-mentioned developer waste liquid treatment systems 1A and 1B. That is, a separate permeate return pipe 69 is provided, which is connected to the permeate tank 62 disposed in the permeate pipe 61. The separate permeate return pipe 69 is provided with a separate RO membrane device 72 for concentrating the permeate in the permeate tank 62, and a permeate concentrated water tank 73 for temporarily storing the concentrated water from the separate RO membrane device 72. Another permeate return pipe 69 connects the concentration side 72C of the other RO membrane device 72 to the concentrated permeate tank 73. The other permeate return pipe 69 may be connected directly to the concentrated permeate tank 73, or, as shown, may be connected to the permeate return pipe 66 upstream of the concentrated permeate tank 73. This permeate return pipe 66 is preferably the same as the permeate return pipe 66 of the above-mentioned developing waste liquid treatment system 1A. The permeate return pipe 66 is preferably provided with the permeate concentrated water tank 73, and further with a permeate transfer means 75 on the liquid tank 31 side. Another permeate pipe 74 is preferably connected to a dilute TAAH wastewater treatment facility 93 on the permeation side 72T of another RO membrane device 72. The permeate return pipe 66 preferably has a valve 67 downstream of the branch with the permeate return pipe 66. Also, the permeate pipe 61 preferably has a valve 68 downstream of the branch with the permeate return pipe 66. When treating waste developer, valve 68 is opened and valve 67 is closed. Valve 71 is opened and valve 70 is closed. On the other hand, when cleaning, valve 67 is opened and valve 68 is closed. In this way, a permeate return system 60C (permeate side circulation system) is configured in which the liquid tank 31 passes through the cleaning liquid supply system 30C, the permeate side 21T of the RO membrane device 21, the permeate pipe 61, the permeate return pipe 66, and the permeate concentrated water tank 73 and is returned to the liquid tank 31. Other configurations are the same as those of the development waste liquid treatment systems 1A and 1B. The development waste liquid is treated in the same manner as in the development waste liquid treatment system 1A.

[0059] In the cleaning system 100C, the cleaning liquid is RO membrane permeated water of developer wastewater stored in the permeated water tank 62. Therefore, the resist concentration of the cleaning liquid is, for example, 0.027, which is sufficiently low. Moreover, because the cleaning liquid passes through a separate RO membrane device 72, moisture is permeated to the permeation side 72T, and the TMAH concentration is increased on the concentration side 72C. Therefore, concentrated water with an increased TMAH concentration is obtained. During cleaning, it is also preferable to collect the cleaning liquid permeate that has permeated the RO membrane device 21 in the permeated water tank 62 and reuse it as cleaning liquid. However, since a sufficient flow rate cannot be ensured with the cleaning liquid permeate alone during cleaning, it is preferable to return the cleaning liquid concentrate obtained by treating the cleaning liquid with the RO membrane to the liquid tank 31 and reuse it as cleaning liquid. This ensures the minimum amount of concentrate (cleaning flow rate) for the RO membrane 21F.

[0060] Furthermore, since the cleaning liquid concentrate is concentrated water obtained after the cleaning liquid has passed through the RO membrane device 21, the resist concentration is significantly lower than that of the concentrated water discharged during the treatment of the developer waste liquid. Moreover, the cleaning liquid concentrate contains resist because it is combined with the cleaning liquid permeate water to form the cleaning liquid, but the resist concentration is significantly lower than that of the developer waste liquid, and it has sufficient ability to remove resist from the surface of the RO membrane 21 (the concentrated side 21C of the RO membrane 21F).

[0061] As described above, if the concentrated water return system 40C is not provided in the cleaning system 100C, it will be necessary to increase the amount of permeated water supplied from the permeated water tank 62 in order to ensure the amount of cleaning liquid. Furthermore, when the cleaning liquid concentrate produced from the concentration side 21C is supplied to the concentrated water tank 42, the concentration of the concentrate stored in the concentrated water tank 42 becomes lower than the concentration of the concentrate obtained by treating the developer waste liquid. Therefore, it is preferable to return the entire amount of concentrated water in the case of cleaning to the liquid tank 31. In this way, it is preferable to ensure the amount of cleaning liquid supplied to the RO membrane device 21 so that the amount of concentrated water discharged is equal to or greater than the minimum amount of concentrated water discharged from the RO membrane 21F.

[0062] Since the above-mentioned cleaning is performed using permeated water obtained by treating the developer waste liquid with the RO membrane device 21, there is no need to remove the cleaning liquid in the developer waste liquid treatment system 1C and perform pure water cleaning, and the developer waste liquid can be treated immediately after the cleaning process.

[0063] As described above, in the third embodiment of the system for treating a developer waste liquid as a system for treating a TAAH-containing liquid of the present invention, the system for treating a developer waste liquid includes: (a-3) a liquid tank for storing developer waste generated in a photolithography process; (b-3) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-3) a reverse osmosis membrane device (Y) connected to the other end of the liquid supply pipe; (d-3) a concentrated water pipe connected to the concentration side of the reverse osmosis membrane device at one end and supplying the concentrated water of the reverse osmosis membrane device to an evaporator; (e-3) a concentrated water return pipe connected to the concentrated water pipe and supplying the concentrated water of the reverse osmosis membrane device (Y) to the liquid tank; (f-3) a permeate pipe (P) having one end connected to the permeation side of the reverse osmosis membrane device (Y); (g-3) a permeated water tank disposed midway through the permeated water piping (P); (h-3) a diluted TAAH wastewater treatment facility connected to the other end of the permeate piping (P); (i-3) a permeate return pipe (I) connected to the permeate pipe (P) located between the reverse osmosis membrane device (Y) and the permeate tank, for supplying the permeate from the reverse osmosis membrane device (Y) to the liquid tank; (j-3) a permeate concentration tank disposed midway through the permeate return pipe (I); (k-3) another permeate return pipe (II) branching from the permeate pipe (P) located between the permeate tank and the diluted TAAH wastewater treatment equipment and connected to the permeate return pipe (I) located between the reverse osmosis membrane device (Y) and the permeate concentrated water tank; (l-3) another reverse osmosis membrane device (Z) arranged in the middle of the other permeate return pipe (II); (m-3) another permeate piping (Q) connecting the permeation side of the other reverse osmosis membrane device (Z) to the diluted TAAH wastewater treatment facility; The cleaning system is a system for cleaning the reverse osmosis membrane of the reverse osmosis membrane device by supplying concentrated water (X) obtained by concentrating permeate from the reverse osmosis membrane device (Y) in the other reverse osmosis membrane device (Z) to the liquid tank, and circulating the concentrated water (X) through both the circulation system formed by the above (a-3) to (d-3) and (e-3), and the circulation system formed by the above (a-3) to (c-3), (f-3), (i-3) and (j-3).

[0064] Next, a description will be given with reference to a preferred embodiment (Fourth Embodiment) of a treatment system 1 (1D) for a developer waste liquid as a treatment system for a TAAH-containing liquid equipped with a cleaning system 100 (100D). 8, the development waste liquid treatment system 1D has a configuration in which a concentrated water permeation system 50 that supplies concentrated water from a concentrated water tank 42 to a concentrated water return pipe 46 is incorporated into a concentrated water return system 40D similar to the concentrated water return system 40A of the development waste liquid treatment system 1A described above. That is, it is preferable that the concentrated water permeation pipe 51 of the concentrated water permeation system 50 branches off from the concentrated water pipe 41 between the concentrated water transfer means 43 and the evaporator 11, and is connected to the concentrated water return pipe 46 between the cooler 91 and the flow meter 87. It is preferable that a nanofiltration (NF) device 52, an NF permeated water tank 53, and an NF permeated water transfer means 54 are arranged in the concentrated water permeation pipe 51 in this order from the branching side with the concentrated water pipe 41. It is also preferable that the concentrated water permeation pipe 51 is connected to the permeation side of the NF device 52, and that a concentrated water pipe 55 connected to the evaporator 11 is connected to the concentration side 21C of the NF device 52. The concentrated water permeation pipe 51 is preferably provided with a valve 56 at the branching point with the concentrated water pipe 41 , and the concentrated water pipe 41 is preferably provided with a valve 57 on the evaporator 11 side of the branching point with the concentrated water permeation pipe 51 . In this way, a concentrated water return system 40D (concentrated water circulation system) is configured, which runs from the liquid tank 31 through the cleaning liquid supply system 30D, the concentrated side 21C of the RO membrane device 21, the concentrated water piping 41, and the concentrated water return piping 46 and returns to the liquid tank 31. Other configurations are the same as those of the development waste liquid treatment system 1A. Furthermore, the development waste liquid treatment is the same as that of the development waste liquid treatment system 1A.

[0065] When cleaning is performed using the cleaning system 100D, it is preferable to first remove all liquid from the cleaning system 100D and then supply new TMAH liquid as a cleaning liquid to the liquid tank 31, as in the cleaning system 100A. During cleaning, valves 47 and 48 on the concentration side are opened. The opening amounts are adjusted appropriately. At the same time, valve 57 is closed and valve 56 is opened. At the same time, valve 68 on the permeation side is closed and valve 67 is opened. In the cleaning system 100D, new TMAH solution is used as the cleaning solution, and therefore the TMAH concentration is high (for example, 2.38 mass %), resulting in excellent resist cleaning performance for the RO membrane 21F. However, since the flow rate of new TMAH solution alone is insufficient as a cleaning solution, the cleaning solution permeate discharged from the RO membrane device 21 and the cleaning solution concentrate discharged from the RO membrane device 21 are also used. A portion of the cleaning solution concentrate is returned directly to the liquid tank 31 by the concentrate return system 40D, while the remainder is stored in the concentrate layer 42. The cleaning solution concentrate stored in the concentrate tank 42 is passed through the NF device 52. In the NF device 52, the resist is removed and the TMAH aqueous solution permeates and is supplied from the concentrate permeation pipe 51 to the concentrate pipe 46 and then sent to the liquid tank 31. Therefore, a liquid with a low resist concentration (e.g., resist concentration 0.012) and an increased TMAH concentration (e.g., TMAH concentration 2.21 mass %) is supplied to the liquid tank 31 by the RO membrane device 21. Therefore, even if a portion of the concentrated cleaning solution is directly supplied to the liquid tank 31, the resist concentration is diluted and the TMAH concentration is increased. In the above system, TMAH is hardly removed, and the resist is removed by the NF device 52. Therefore, the resist concentration is lower (e.g., 1 / 99 or less) than when the entire amount of the concentrated cleaning solution is returned to the liquid tank 31. Because a sufficient flow rate of the cleaning solution cannot be ensured by the cleaning solution permeate alone, the concentrated cleaning solution obtained by RO membrane treatment of the cleaning solution is also returned to the liquid tank 31 and reused as the cleaning solution. This ensures the minimum concentrated water flow rate (cleaning flow rate) of the RO membrane 21F. The concentrated cleaning solution is the concentrated water obtained after passing the new TMAH solution through the RO membrane device 21, and therefore has a lower resist concentration than the concentrated water discharged during the treatment of waste developer. Therefore, the cleaning solution, which is a combination of the permeated water and concentrated water, has a sufficiently low resist concentration and is capable of removing resist from the reverse osmosis membrane surface.

[0066] Since the above cleaning is performed using new TMAH solution, there is no need to remove the cleaning solution in the waste developer treatment system 1D and perform pure water cleaning, and the waste developer treatment can be performed immediately after the cleaning process.

[0067] As described above, in the fourth embodiment of the system for treating a developer waste liquid as a system for treating a TAAH-containing liquid of the present invention, the system for treating a developer waste liquid is (a-4) a liquid tank for storing developer waste generated in a photolithography process; (b-4) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-4) a reverse osmosis membrane device connected to the other end of the liquid supply pipe; (d-4) a concentrated water pipe having one end connected to the concentrated side of the reverse osmosis membrane device; (e-4) a concentrated water tank arranged in the middle of the concentrated water piping; (f-4) a concentrated water return pipe connected to the concentrated water pipe located between the reverse osmosis membrane and the concentrated water tank, for supplying the concentrated water of the reverse osmosis membrane device to the liquid tank; (g-4) a concentrated water permeation pipe that branches off from the concentrated water pipe located between the concentrated water tank and the evaporator and connects to the concentrated water return pipe; (h-4) a nanofilter device disposed in the middle of the concentrated water permeation piping; (i-4) a nanofilter permeated water tank disposed midway through the concentrated water permeation piping and storing the permeated water of the nanofilter device; (j-4) a nanofilter concentrated water pipe connected to the concentrated side of the nanofilter device at one end and supplying the concentrated water of the nanofilter device to the evaporator; (k-4) a permeate pipe connected at one end to the permeation side of the reverse osmosis membrane device; (1-4) a diluted TAAH wastewater treatment facility connected to the other end of the permeate piping; (m-4) a permeate return pipe connected to the permeate pipe for supplying permeate to the liquid tank; and The cleaning system supplies fresh TMAH liquid to the liquid tank and circulates the fresh TMAH liquid through both the circulation system formed by the above (a-4) to (e-4) and (f-4) to (i-4), and the circulation system formed by the above (a-4) to (c-4), (k-4), and (m-4), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device.

[0068] Next, a description will be given with reference to a preferred embodiment (Embodiment 5) of a treatment system 1 (1E) for a developer waste liquid as a treatment system for a TAAH-containing liquid equipped with a cleaning system 100 (100E). As shown in Figure 9, the developer waste liquid treatment system 1E is the same as the developer waste liquid treatment system 1C described above, except that another RO membrane device 72 and an NF device 76 are arranged in this order from the permeate transfer means 63 side in another permeate return pipe 69 between the permeate transfer means 63 and the permeate concentrated water tank 73. It is preferable that another permeate return pipe 69 for supplying permeate in the permeate tank 62 is connected to the water supply side 72S of another RO membrane apparatus 72, and that another permeate return pipe 69 is connected from the concentration side 72C of the other RO membrane apparatus 72 to the water supply side 76S of the NF apparatus 76. It is preferable that another permeate pipe 74 is connected to the permeation side 72T of the other RO membrane apparatus 72, to the dilute TAAH wastewater treatment facility 93. It is further preferable that another permeate return pipe 69 is connected from the permeation side 76T of the NF apparatus 76 to the permeate concentration tank 73. It is preferable that the concentration side 76C of the NF apparatus 76 is connected to the another permeate pipe 74 via another concentrate pipe 77. Another permeate return pipe 69 may be connected to a permeate concentrate tank 73 via a permeate return pipe 66 as shown. In this way, a permeate return system 60E (concentration side circulation system) is configured, which runs from the liquid tank 31 through the cleaning liquid supply system 30E, the permeation side 21T of the RO membrane device 21, the permeate piping 61, the permeate return piping 66, and the permeate concentrated water tank 73 and returns to the liquid tank 31. Other configurations are the same as those of the waste developer treatment system 1C. To treat waste developer using the waste developer treatment system 1E, it is preferable to operate the valves in the same manner as in the waste developer treatment system 1A. During cleaning, it is preferable to close valve 71 and open valve 70 in order to send permeated water from the permeated water tank 62, which stores the permeated water in the development piping, to the liquid tank 31. After the permeated water from the NF membrane device 76 has accumulated in the permeated water concentration tank 73, it is preferable to close valve 68 again and open valve 67.

[0069] In the cleaning system 100E, it is preferable to use, as the cleaning liquid, the permeated water of the developer wastewater stored in the permeated water tank 62, which is passed through another RO membrane device 72 and then the resulting concentrated water, which is further passed through the NF filter device 76. Therefore, the RO membrane device 72 discharges water from the permeated water of the developer wastewater to the permeate side, while the TMAH remains in the concentrated side, thereby increasing the TMAH concentration. Furthermore, this liquid with an increased TMAH concentration passes through the NF filter device 76, allowing the TMAH to pass through and removing the resist. Therefore, the cleaning liquid is supplied to the concentrated permeated water tank 73 as a liquid with an increased TMAH concentration and a reduced resist concentration. The resist concentration of this cleaning liquid is, for example, 0.001, which is sufficiently low. Furthermore, passing the cleaning liquid through the separate RO membrane device 72 concentrates the TMAH concentration, preventing it from becoming too low. As the cleaning liquid cannot ensure a sufficient flow rate with only the permeated developer waste liquid, it is preferable to also return the cleaning liquid concentrated water obtained by treating the cleaning liquid with the RO membrane to the liquid tank 31 and reuse it as cleaning liquid. This ensures the minimum amount of concentrated water (cleaning flow rate) for the RO membrane 21F. Furthermore, since the concentrated cleaning solution is concentrated water obtained after the cleaning solution has passed through the RO membrane device 21, the resist concentration is lower than that of the concentrated water discharged during the treatment of waste developer solution. Moreover, the concentrated cleaning solution contains resist because it is combined with the permeated cleaning solution to form the cleaning solution, but the resist concentration is significantly lower than that of the waste developer solution, so it has sufficient ability to remove resist from the reverse osmosis membrane surface.

[0070] As described above, if the cleaning system 100E is not provided with the concentrated water return system 40E, it will be necessary to increase the amount of permeated water supplied from the permeated water tank 62 in order to ensure the amount of cleaning liquid. Furthermore, if the concentrated cleaning liquid water generated from the concentration side 21C is supplied to the concentrated water tank 42, the concentration of the concentrated water stored in the concentrated water tank 42 will be diluted when the developer waste liquid after cleaning is treated. Therefore, it is preferable to return the entire amount of concentrated water in the case of cleaning to the liquid tank 31. In this way, it is preferable to ensure the amount of cleaning liquid supplied to the RO membrane device 21 so that the amount of concentrated water discharged is equal to or greater than the minimum amount of concentrated water discharged from the RO membrane 21F.

[0071] Since the above-mentioned cleaning is performed using permeated water obtained by treating the developer waste liquid with the RO membrane device 21, there is no need to remove the cleaning liquid in the developer waste liquid treatment system 1E and perform pure water cleaning, and the developer waste liquid can be treated immediately after the cleaning process.

[0072] As described above, in the fifth embodiment of the system for treating a developer waste liquid as a system for treating a TAAH-containing liquid of the present invention, the system for treating a developer waste liquid includes: (a-5) a liquid tank for storing developer waste generated in a photolithography process; (b-5) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-5) a reverse osmosis membrane device (Y) connected to the other end of the liquid supply pipe; (d-5) a concentrated water pipe connected to the concentration side of the reverse osmosis membrane device at one end and supplying the concentrated water of the reverse osmosis membrane device to an evaporator; (e-5) a concentrated water return pipe connected to the concentrated water pipe and supplying the concentrated water of the reverse osmosis membrane device (Y) to the liquid tank; (f-5) a permeate pipe (P) having one end connected to the permeation side of the reverse osmosis membrane device (Y); (g-5) a permeated water tank disposed midway through the permeated water piping (P); (h-5) a diluted TAAH wastewater treatment facility disposed at the other end of the permeate piping (P); (i-5) a permeate return pipe (I) connected to the permeate pipe (P) located between the reverse osmosis membrane device (Y) and the permeate tank, for supplying the permeate from the reverse osmosis membrane device (Y) to the liquid tank; (j-5) a permeate concentration tank disposed midway through the permeate return pipe (I); (k-5) another permeate return pipe (II) branching from the permeate pipe (P) located between the permeate tank and the diluted TAAH wastewater treatment equipment and connecting to the permeate return pipe (I) located between the reverse osmosis membrane device (Y) and the permeate concentrated water tank; (l-5) another reverse osmosis membrane device (Z) arranged in the middle of the other permeate return pipe (II); (m-5) a nanofilter device disposed in the other permeate return pipe (II) and treating the concentrated water of the other reverse osmosis membrane device (Z); (n-5) another permeate piping (Q) connecting the permeation side of the other reverse osmosis membrane device (Z) to the diluted TAAH wastewater treatment facility; (o-5) a nanofilter concentrate pipe that connects the concentrate side of the nanofilter device to the separate permeate pipe (Q), The cleaning system is a system for cleaning the reverse osmosis membrane of the reverse osmosis membrane device by supplying treated permeate water, which is obtained by concentrating the permeate water from the reverse osmosis membrane device (Y) in the other reverse osmosis membrane device (Z) and then passing it through the nanofilter device, to the liquid tank, and circulating the treated permeate water through both the circulation system formed by the above (a-5) to (d-5) and (e-5), and the circulation system formed by the above (a-5) to (c-5), (f-5) and (i-5).

[0073] In each of the waste developer treatment systems 1B to 1E, when treating waste developer, the waste developer is supplied to the liquid tank 31 and sent to the RO membrane device 21 through the liquid supply pipe 32, similar to the waste developer treatment system 1A. The RO membrane device 21 separates the waste developer into concentrated water and permeate. A portion of the concentrated water is returned to the liquid tank 31 through the concentrated water return system 40 after being cooled by the cooler 91. On the other hand, the remainder of the concentrated water is guided to the concentrated water tank 42 through the concentrated water pipe 41 and sent to the evaporator 11. In treating waste developer, it is preferable to operate the valves to prevent the waste developer from flowing into the cleaning liquid system. For example, it is preferable to close valve 67 in treatment system 1A, valve 70 in treatment system 1B, valves 67 and 70 in treatment systems 1C and 1E, and valves 56 and 67 in treatment system 1D.

[0074] Although an example of mass balance has been shown for the above-mentioned development waste liquid treatment system 1A, the mass balance can also be set appropriately for the other development waste liquid treatment systems 1B to 1E in accordance with the use of membranes such as RO membranes and NF membranes.

[0075] Each of the waste developer treatment systems 1A to 1E preferably has a means for measuring the resist concentration of the cleaning solution supplied from the solution tank 31 by the cleaning systems 100A to 100E. For example, it is preferable to obtain a sample from the sampling pipe 34 and measure the resist concentration of the sample by absorptiometry, for example, using the above-mentioned spectrophotometer. It is also preferable to have a cleaning status detection means (not shown) that detects the cleaning status from the measured resist concentration. This cleaning status detection means, for example, compares the measured resist concentration with a threshold resist concentration at which cleaning is necessary, to determine whether or not to perform the cleaning process.

[0076] In the above-mentioned waste developer treatment systems 1A to 1E, it is preferable to detect the membrane clogging state of the RO membrane 21F of the RO membrane device 21 by measuring one or more of the treated water volume, permeate volume, operating pressure, and transmembrane pressure difference (the difference between the pressure on the feedwater side and the pressure on the permeate side) of the RO membrane device 21. As a detection method, the treated water volume of the RO membrane device 21 is calculated from the total value of the flow rates measured by flow meters 86 to 88. The permeate volume is measured by flow meter 88. The operating pressure is measured by pressure gauge 81. The transmembrane pressure difference (the difference between the feedwater side pressure and the permeate side pressure) is measured by pressure gauges 81 and 83, and this pressure difference is calculated.

[0077] In the above-mentioned waste developer treatment systems 1A to 1E, it is preferable to determine whether or not to transition to a cleaning process for the RO membrane device 21 based on the detected clogging state of the RO membrane 21F, and if transition to a cleaning process is necessary, to transition to a cleaning process for the RO membrane device. It is preferable to determine whether or not to proceed to the cleaning step when at least one of the following conditions occurs: the amount of treated water is about 60% by mass of the initial amount; the amount of permeated water is about 60% by mass of the initial amount; the operating pressure is about 1.8 MPa by mass; or the transmembrane pressure difference is about 1.8 MPa. In the above-described waste developer treatment systems 1A and 1B, fresh TMAH solution is used as the cleaning solution, but in waste developer treatment systems 1C and 1E, concentrated water containing TMAH is stored in the permeate concentrated water tank 73, and in waste developer treatment system 1D, permeate water containing TMAH is stored in the NF permeate tank 53, and this stored solution can be used as the cleaning solution. Therefore, less fresh TMAH solution is required than in waste developer treatment systems 1A and 1B. Furthermore, waste developer treatment systems 1C to 1E aim to recover as much TMAH as possible from the wastewater and use it as the cleaning solution, and this goal has been achieved. Fresh TMAH solution can, of course, also be used in waste developer treatment systems 1C to 1E.

[0078] The above-mentioned RO membrane device and NF membrane device have a single-stage configuration, but may have a multi-stage configuration. In this case, it is preferable to arrange multiple stages in series, whether it is the RO membrane or the NF membrane. It is preferable that at least one stage of the multi-stage RO membrane device is a high-pressure RO membrane device. [Example]

[0079] Example 1 In Example 1, the treatment system 1A for treating developer wastewater shown in Fig. 1 was used to concentrate the developer wastewater and clean the water supply side 21F of the RO membrane 21F. The RO membrane 21F of the RO membrane device 21 was a 4-inch SWC5 marine freshwater membrane manufactured by Nitto Denko Corporation, with a membrane area of ​​37.1 m. 2 As mentioned above, this RO membrane (SWC5) was confirmed to have no problems with its materials or use even in continuous operation for 3,620 hours (approximately 150 days) at a pH of approximately 12. The mass balance when the developer waste solution was treated was set in the same manner as shown in FIG. 2 above by adjusting the openings of the valves 47 and 48. Therefore, when treating the waste developer solution, valves 47 and 48 were opened by adjusting their opening degrees, and valve 68 was opened and valve 67 was closed. On the other hand, during the cleaning process, valve 47 was opened and valve 48 was closed, and valve 67 was opened and valve 68 was closed. Treatment of the waste developer solution continued in this state, and one cleaning process was carried out when the permeation flux approached 0.4 m / d. The treatment process of the waste developer solution, which lasted approximately 1,200 hours, was carried out three times, during which two cleaning processes were carried out. One cleaning process lasted 4.75 hours, including the time to remove the waste developer solution, the time to add the cleaning solution, the time for cleaning, and the time to remove the cleaning solution. The waste developer used was the same as that actually discharged in semiconductor manufacturing. The operating pressure was set to 1.8 MPa or higher. The processing conditions were set as described above, and the developer waste solution was processed. Samples were taken from the sampling pipes 34, 44, and 64 on the supply side, concentration side, and permeation side of the RO membrane device 21, respectively, and the pH, TMAH concentration, and resist concentration (absorbance at 290 nm) of each test liquid (developer wastewater, RO membrane feed water, RO membrane concentrated water, and RO membrane permeate water) were measured. The results are shown in Table 1. Figure 3 shows the relationship between the elapsed time during the treatment of the developer wastewater and the permeation flux (m / d). As the treatment of the developer wastewater progressed, the permeation flux decreased. When the permeation flux reached approximately 0.4 m / d, the process moved to the cleaning step, and the RO membrane was cleaned. The timing of the cleaning can be set arbitrarily. As a result of the cleaning process, as shown in Figure 3, both the permeation flux and operating pressure returned to their initial states. The initial state refers to the state immediately before the start of treatment of the developer wastewater. Furthermore, even when the developer wastewater concentration process and cleaning process were repeated, both the permeation flux and operating pressure returned to their initial states each time the cleaning process was performed. In this way, by periodically performing the cleaning process, it became possible to restore the treatment capacity of the RO membrane 21F and extend its lifespan. The cleaning solution used was a new TMAH developer with a TMAH concentration of 2.50% by mass. This new TMAH developer is unused TMAH developer used in the photoresist development process. As shown in Table 2 above, for example, 0.25 hours after the start of cleaning, the TMAH concentration dropped to 2.20% by mass due to contamination by waste developer with a low TMAH concentration that remained in the system. This may be due to contamination by permeated water with a low TMAH concentration, for example. After the TMAH concentration dropped, it stabilized at approximately the same value. Since the cleaning solution after cleaning is TMAH, resist, and water, the cleaning solution can be directly poured into the concentrated water tank after the cleaning process.

[0080] (Comparative Example 1) In Comparative Example 1, except that the cleaning step was not performed, the treatment of the developer waste was carried out in the same manner as in Example 1. Therefore, the pH, TMAH concentration, and resist concentration (absorbance at 290 nm) of the developer waste, RO membrane feed water, RO membrane concentrate, and RO membrane permeate collected from the collection pipes 34, 44, and 64 on the supply side, concentration side, and permeation side of the RO membrane device 21 were the same as those in Example 1. The relationship between the elapsed time of developer waste treatment and the permeation flux (m / d) is shown in Figure 3. As the treatment of developer wastewater progressed, the permeation flux decreased. When the permeation flux reached approximately 0.4 m / d, the change in permeation flux became small. When the operating pressure reached approximately 1.8 MPa, the change in operating pressure became small. Thus, without carrying out the cleaning process, the treatment capacity of the RO membrane 21F could not be restored, and it became necessary to replace the RO membrane 21F.

[0081] (Comparative Example 2) Washing was performed in the same manner as in Example 1, except that a 2.5% by mass aqueous solution of sodium hydroxide (NaOH) was used as the washing solution. Therefore, the washing time was 4 hours. The permeation flux before and after washing was 0.422 m / d and 0.685 m / d, respectively. Thus, washing with a 2.5% by mass aqueous solution of NaOH produced results equivalent to those obtained with TMAH washing. Although the permeation flux returned, pure water washing was required to remove the NaOH. Pure water washing was performed until the sodium concentration reached 0.005% by mass or less, the same as that of the waste developer, to prevent the influence of sodium ions on the recovered TMAH (see Table 4 and Figure 5 above). Pure water washing was performed by continuously flowing pure water through the system. The cleaning time required was 0.25 hours to remove the developer waste, 0.25 hours to add the cleaning solution, 4 hours for cleaning, 0.25 hours to remove the cleaning solution, 0.25 hours to add pure water, 10 hours for pure water cleaning in the system, and 0.25 hours to remove the pure water cleaning solution, for a total of 15.25 hours of cleaning time (see Table 3 above). As a result, it was found that cleaning using TMAH in the treatment system for developer waste solution of the present invention requires fewer cleaning steps, takes less time, and allows cleaning to be performed efficiently and at low cost.

[0082] Examples 2 to 5 In Example 2, the processing system 1B for processing waste developer shown in Figure 6 was used to concentrate the waste developer and to clean the RO membrane 21. New TMAH developer was used as the cleaning solution. Other conditions were the same as in Example 1. In Example 3, the processing system 1C for treating developer waste liquid shown in Fig. 7 was used to perform the concentration processing of the developer waste liquid and the cleaning process of the RO membrane 21. The cleaning liquid used was concentrated water obtained by concentrating the permeate of the developer waste liquid that had permeated the RO membrane device 21 using another RO membrane device 72. Other conditions were the same as those in Example 1. In Example 4, the processing system 1D for processing waste developer shown in Fig. 8 was used to concentrate the waste developer and to clean the RO membrane 21. New TMAH developer was used as the cleaning solution. Other conditions were the same as in Example 1. In Example 5, a process of concentrating a developer waste liquid and a cleaning process of the RO membrane 21 were carried out using the developer waste liquid treatment system 1E shown in Fig. 9. The cleaning liquid was a permeate obtained by concentrating the permeate of the developer waste liquid that had passed through the RO membrane device 21 using another RO membrane device 72 and then passing the concentrated water through the NF membrane device 76. Other conditions were the same as in Example 1. For the NF membranes in Examples 4 and 5, a Nitto Denko NF model NTR-7450 was used. The results of cleaning for each of Examples 1 to 5 are shown in Table 5.

[0083] As shown in Table 5, the TMAH concentrations in the cleaning solutions in Examples 1 to 5 were 2.20 to 2.38. All of these TMAH concentrations were sufficient to clean the resist on the RO membrane 21F. The resist concentrations immediately before supplying the solutions to the RO membrane 21F were 0.000 to 0.027, which were all sufficiently low values. After washing, the permeation flux recovered to 0.68 to 0.70. The recovery rate was almost 97% or more for all solutions, demonstrating that TMAH washing using the treatment system for developer waste solution of the present invention was effective.

[0084] [Table 5]

[0085] Although the present invention has been described in conjunction with examples thereof, we do not intend to limit our invention to any of the details of the description unless otherwise specified, and believe that the claims should be broadly construed without departing from the spirit and scope of the invention as set forth in the appended claims.

[0086] This application claims priority based on Japanese Patent Application No. 2018-197694, filed on October 19, 2018, the contents of which are incorporated herein by reference as part of the present specification. [Explanation of symbols]

[0087] 1, 1A, 1B, 1C, 1D, 1E TAAH-containing liquid treatment system 11 Evaporator 21 Reverse osmosis membrane device (RO membrane device) 21F RO membrane 21S Water supply side 21C Concentration side 21T Transmission side 30 Treated liquid supply system 30A cleaning solution supply system 31 Liquid tank 32 Liquid supply piping 33 Liquid transfer means 34 Liquid sampling piping (sampling piping) 35, 45, 47, 48, 56, 65, 67, 68, 70, 71 valves 40, 40A, 40B, 40C, 40D, 40E Concentrated water return system 41 Concentrated water piping 42 Concentrated water tank 43 Concentrated water transfer means 44 Concentrated water collection piping 46 Concentrated water return pipe 50 Concentrated water permeation system 51 Concentrated water permeation piping 52NF device 53 NF permeable water tank 54 NF Permeate water transfer means 55 Concentrated water piping 60, 60A, 60B, 60C, 60D, 60E Permeate return system 61 Permeated water piping 62 Permeation tank 63 Permeated water transfer means 64 Permeated water collection piping (sampling piping) 66 Permeate return pipe 67, 68 Flowmeter 69 Permeate return pipe, separate permeate return pipe 71, 86, 87, 88 flowmeter 72 Another RO membrane device 72S Water supply side 72C Concentration side 72T Transmission side 73 Permeate concentration tank 74 Separate permeate piping 75 Permeated water transfer means 76 NF equipment 77 Separate concentrated water piping 81, 82, 83 Pressure gauges 86, 87, 88 flowmeter 91 Cooler 93 Dilute TAAH wastewater treatment equipment 100, 100A, 100B, 100C, 100D, 100E Cleaning Systems

Claims

1. A treatment system for a tetraalkylammonium hydroxide-containing liquid, which is supplied with a treated liquid containing resist and tetraalkylammonium hydroxide and having a pH of 12 or more, and which has a high-pressure reverse osmosis membrane device that concentrates the treated liquid on the concentration side, and a line that supplies the treated liquid concentrated by the reverse osmosis membrane device to an evaporator that further concentrates the treated liquid, a part of the treatment system can be a circulation system including the reverse osmosis membrane device, and by circulating a cleaning solution containing tetraalkylammonium hydroxide through the circulation system, the circulation system can be used as a cleaning system for cleaning the reverse osmosis membrane of the reverse osmosis membrane device; A system for treating a tetraalkylammonium hydroxide-containing liquid, wherein the cleaning liquid contains a new tetraalkylammonium hydroxide liquid, and / or the liquid to be treated contains a concentrated liquid obtained by passing the permeate that has permeated the reverse osmosis membrane device through another reverse osmosis membrane device.

2. 2. The system for treating a tetraalkylammonium hydroxide-containing liquid according to claim 1, wherein the reverse osmosis membrane in the reverse osmosis membrane device has a tetramethylammonium hydroxide removal rate of 99.5% by mass or more and a resist removal rate of 99.5% by mass or more.

3. The treatment system for the tetraalkylammonium hydroxide-containing liquid comprises: (a-1) a liquid tank for storing a tetraalkylammonium hydroxide-containing liquid; (b-1) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-1) a reverse osmosis membrane device to which the other end of the liquid supply pipe is connected; (d-1) a concentrated water pipe having one end connected to the concentration side of the reverse osmosis membrane device and supplying concentrated water from the reverse osmosis membrane device to an evaporator; (e-1) a concentrated water return pipe connected to the concentrated water pipe and supplying the concentrated water of the reverse osmosis membrane device to the liquid tank; (f-1) a permeate pipe having one end connected to the permeation side of the reverse osmosis membrane device; (g-1) a dilute tetraalkylammonium hydroxide wastewater treatment facility connected to the other end of the permeate piping; (h-1) a permeate return pipe connected to the permeate pipe and supplying the permeate of the reverse osmosis membrane device to the liquid tank; and The cleaning system is a system for treating a tetraalkylammonium hydroxide-containing liquid according to claim 1, wherein the cleaning system supplies a new tetraalkylammonium hydroxide liquid to the liquid tank and circulates the new tetraalkylammonium hydroxide liquid through both a circulation system formed by (a-1) to (d-1) and (e-1) and a circulation system formed by (a-1) to (c-1), (f-1) and (h-1), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device.

4. The treatment system for the tetraalkylammonium hydroxide-containing liquid comprises: (a-3) a liquid tank for storing a tetraalkylammonium hydroxide-containing liquid; (b-3) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-3) a reverse osmosis membrane device (Y) connected to the other end of the liquid supply pipe; (d-3) a concentrated water pipe connected at one end to the concentration side of the reverse osmosis membrane device and supplying the concentrated water of the reverse osmosis membrane device to an evaporator; (e-3) a concentrated water return pipe connected to the concentrated water pipe and supplying the concentrated water of the reverse osmosis membrane device (Y) to the liquid tank; (f-3) a permeate pipe (P) having one end connected to the permeation side of the reverse osmosis membrane device (Y); (g-3) a permeated water tank disposed in the permeated water piping (P); (h-3) a dilute tetraalkylammonium hydroxide wastewater treatment facility connected to the other end of the permeate piping (P); (i-3) a permeate return pipe (I) connected to the permeate pipe (P) located between the reverse osmosis membrane device (Y) and the permeate tank, for supplying the permeate of the reverse osmosis membrane device (Y) to the liquid tank; (j-3) a permeate concentration tank disposed in the permeate return pipe (I); (k-3) another permeate return pipe (II) branching from the permeate pipe (P) located between the permeate tank and the diluted tetraalkylammonium hydroxide wastewater treatment facility and connected to the permeate return pipe (I) located between the reverse osmosis membrane device (Y) and the permeate concentrated water tank; (l-3) another reverse osmosis membrane device (Z) arranged in the middle of the other permeate return pipe (II); (m-3) another permeate piping (Q) connecting the permeation side of the other reverse osmosis membrane device (Z) to the dilute tetraalkylammonium hydroxide wastewater treatment facility; The cleaning system is a system for treating a tetraalkylammonium hydroxide-containing liquid according to claim 1, wherein concentrated water (X) obtained by concentrating permeate from the reverse osmosis membrane device (Y) in the other reverse osmosis membrane device (Z) is supplied to the liquid tank, and the concentrated water (X) is circulated through both a circulation system formed by the (a-3) to (d-3) and (e-3) and a circulation system formed by the (a-3) to (c-3), (f-3), (i-3) and (j-3), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device.

5. The treatment system for the tetraalkylammonium hydroxide-containing liquid comprises: (a-4) a liquid tank for storing a tetraalkylammonium hydroxide-containing liquid; (b-4) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-4) a reverse osmosis membrane device connected to the other end of the liquid supply pipe; (d-4) a concentrated water pipe connected at one end to the concentration side of the reverse osmosis membrane device and supplying the concentrated water of the reverse osmosis membrane device to an evaporator; (e-4) a concentrated water tank arranged in the concentrated water piping; (f-4) a concentrated water return pipe connected to the concentrated water pipe located between the reverse osmosis membrane device and the concentrated water tank and supplying the concentrated water of the reverse osmosis membrane device to the liquid tank; (g-4) A concentrated water permeation pipe branching from the concentrated water pipe located downstream of the concentrated water tank and connected to the concentrated water return pipe; (h-4) a nanofilter device disposed in the concentrated water permeation piping; (i-4) a nanofilter permeated water tank arranged in the middle of the concentrated water permeation piping and storing the permeated water of the nanofilter device; (j-4) a nanofilter concentrate pipe having one end connected to the concentrate side of the nanofilter device and supplying the concentrate of the nanofilter device to the evaporator; (k-4) a permeate pipe having one end connected to the permeation side of the reverse osmosis membrane device; (l-4) a dilute tetraalkylammonium hydroxide wastewater treatment facility connected to the other end of the permeate piping; (m-4) a permeate return pipe connected to the permeate pipe and supplying permeate to the liquid tank; and The system for treating a tetraalkylammonium hydroxide-containing liquid according to claim 1, wherein the cleaning system supplies a new tetraalkylammonium hydroxide liquid to the liquid tank and circulates the new tetraalkylammonium hydroxide liquid through both a circulation system formed by (a-4) to (e-4) and (f-4) to (i-4), and a circulation system formed by (a-4) to (c-4), (k-4) and (m-4), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device.

6. The treatment system for the tetraalkylammonium hydroxide-containing liquid comprises: (a-5) a liquid tank for storing a tetraalkylammonium hydroxide-containing liquid; (b-5) a liquid supply pipe having one end connected to the liquid discharge side of the liquid tank; (c-5) a reverse osmosis membrane device (Y) connected to the other end of the liquid supply pipe; (d-5) a concentrated water pipe connected at one end to the concentration side of the reverse osmosis membrane device and supplying the concentrated water of the reverse osmosis membrane device to an evaporator; (e-5) a concentrated water return pipe connected to the concentrated water pipe and supplying the concentrated water of the reverse osmosis membrane device (Y) to the liquid tank; (f-5) a permeate pipe (P) having one end connected to the permeation side of the reverse osmosis membrane device (Y); (g-5) a permeated water tank disposed in the middle of the permeated water piping (P); (h-5) a diluted tetraalkylammonium hydroxide wastewater treatment facility disposed at the other end of the permeate piping (P); (i-5) a permeate return pipe (I) connected to the permeate pipe (P) located between the reverse osmosis membrane device (Y) and the permeate tank, and supplying the permeate of the reverse osmosis membrane device (Y) to the liquid tank; (j-5) a permeate concentration tank disposed in the permeate return pipe (I); (k-5) another permeate return pipe (II) branching from the permeate pipe (P) located between the permeate tank and the diluted tetraalkylammonium hydroxide wastewater treatment facility and connected to the permeate return pipe (I) located between the reverse osmosis membrane device (Y) and the permeate concentrated water tank; (l-5) another reverse osmosis membrane device (Z) arranged in the middle of the other permeate return pipe (II); (m-5) a nanofilter device disposed in the other permeate return pipe (II) and treating the concentrated water of the other reverse osmosis membrane device (Z); (m-5) another permeate piping (Q) connecting the permeation side of the other reverse osmosis membrane device (Z) to the dilute tetraalkylammonium hydroxide wastewater treatment facility; (o-5) a nanofilter concentrate pipe that connects the concentrate side of the nanofilter device to the separate permeate pipe (Q), The cleaning system is a system for treating a tetraalkylammonium hydroxide-containing liquid according to claim 1, wherein the cleaning system is a system in which permeate water from the reverse osmosis membrane device (Y) is concentrated in the other reverse osmosis membrane device (Z) and then permeated through the nanofilter device, and the treated permeate water is supplied to the liquid tank, and the treated permeate water is circulated through both a circulation system formed by (a-5) to (d-5) and (e-5), and a circulation system formed by (a-5) to (c-5), (f-5) and (i-5), thereby cleaning the reverse osmosis membrane of the reverse osmosis membrane device.

7. A method for treating a tetraalkylammonium hydroxide-containing liquid, comprising: When concentrating a treatment liquid containing resist and tetraalkylammonium hydroxide and having a pH of 12 or more using an evaporator, a concentrating step of concentrating the liquid to be treated to a concentrated side using a reverse osmosis membrane device disposed upstream of the evaporator; the method for treating a tetraalkylammonium hydroxide-containing liquid includes a cleaning step of cleaning the reverse osmosis membrane by circulating a cleaning solution through a circulation system including the reverse osmosis membrane device in response to clogging of the reverse osmosis membrane of the reverse osmosis membrane device, The method for treating a tetraalkylammonium hydroxide-containing liquid, wherein the cleaning liquid contains a new tetraalkylammonium hydroxide solution, and / or the liquid to be treated contains a concentrated liquid obtained by passing the permeate that has permeated the reverse osmosis membrane device through another reverse osmosis membrane.

Images