Method and apparatus for recovering organic solvents

Abstract

The present invention provides an organic solvent recovery method and apparatus that effectively separate water from wastewater and efficiently recover organic solvents such as IPA, thereby reducing the amount of organic solvent waste and lowering the environmental burden. [Solution] The present invention is an organic solvent recovery method for separating water from a liquid to be treated and recovering the organic solvent, wherein a nonlinear calibration curve is prepared that shows the relationship between the concentration of the organic solvent and predetermined physical properties of the liquid to be treated and has one extreme point, the physical properties of the liquid to be treated from which the water has been separated are measured at minute time intervals, the difference ΔP between the first physical property P1 at the first time point and the second physical property P2 at the second time point a minute after the first time point is calculated, the calibration curve portion to which the first physical property P1 or the second physical property P2 belongs is identified from the sign of ΔP, and the concentration of the organic solvent at the first or second time point is estimated. The calibration curve portion is a region of concentration lower than the concentration of the organic solvent at the extreme point or a region of concentration higher than the concentration of the organic solvent at the extreme point.

Description

Technical Field

[0001] The present invention relates to an organic solvent recovery method and an organic solvent recovery apparatus, and more particularly to an organic solvent recovery method and an organic solvent recovery apparatus that separate and remove water from a processing solution used for substrate processing, and concentrate and recover the organic solvent contained in the processing solution.

Background Art

[0002] In manufacturing processes of semiconductor devices and the like, processing using a processing solution is performed on substrates such as semiconductor wafers and glass substrates for liquid crystal display devices. Specifically, a chemical solution is supplied to the main surface of a substrate to perform chemical solution processing on the substrate, and thereafter, water such as deionized water (DIW) is supplied to the main surface of the substrate to which the chemical solution has been supplied, and a rinsing process is performed to wash away the chemical solution on the substrate. Further, after the rinsing process is performed, a drying process is performed to remove water remaining on the substrate and dry the substrate.

[0003] Here, in recent years, along with the miniaturization of patterns formed on substrates such as semiconductor substrates, the aspect ratio (the ratio of height to width of the pattern protrusions) of the protrusions of the uneven pattern has been increasing. Therefore, during the drying process, there is a problem of so-called pattern collapse, in which the surface tension acting on the interface between water that has entered the recesses of the pattern and the gas in contact with the water pulls adjacent protrusions in the pattern toward each other and causes them to collapse. To address such a problem of pattern collapse, for example, a technique of replacing water on a substrate with isopropyl alcohol (IPA) and drying the substrate has been proposed (for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] However, the wastewater generated after replacement with IPA is a mixture of IPA and water, and if it is disposed of as is, it increases the environmental burden. Therefore, if the water can be separated and removed from the wastewater to recover and reuse the IPA, the amount of IPA to be discarded can be reduced, and the increase in the environmental burden can be mitigated.

[0006] This invention was completed in consideration of these problems, and its purpose is to provide an organic solvent recovery method and apparatus that can effectively separate water from wastewater and efficiently recover organic solvents such as IPA, thereby reducing the amount of organic solvent waste and lowering the environmental burden. [Means for solving the problem]

[0007] The organic solvent recovery method according to the present invention is an organic solvent recovery method that, in order to solve the above problems, separates water from a liquid to be treated containing an organic solvent and water, concentrates and recovers the organic solvent, and comprises: a calibration curve preparation step of preparing information for a nonlinear calibration curve that shows the relationship between the concentration of the organic solvent in the liquid to be treated and predetermined physical properties of the liquid to be treated, and has one extreme value point where the physical properties are at their maximum or minimum; a physical property measurement step of measuring the physical properties at minute time intervals in the liquid to be treated from which the water has been continuously separated; and a first physical property P1 measured at a first time point in the physical property measurement step. The method includes a calculation step of calculating the difference ΔP between the first physical property value P1 and the second physical property value P2 measured at a second time point after a minute time interval; a identification step of identifying the calibration curve portion to which the first physical property value P1 or the second physical property value P2 belongs based on the sign of ΔP; and a concentration estimation step of estimating the concentration of the organic solvent at the first time point or the second time point after the execution of the identification step, wherein the calibration curve portion is either a portion of the line in a concentration region lower than the concentration of the organic solvent at the extreme point of the calibration curve, or a portion of the line in a concentration region higher than the concentration of the organic solvent at the extreme point of the calibration curve.

[0008] In a nonlinear calibration curve showing the relationship between the concentration of an organic solvent in a treated liquid and a predetermined physical property of the treated liquid, if there is an extreme value point where the physical property is at a maximum or minimum, there are portions of the calibration curve where the concentration of the organic solvent can be converted, both in the region where the concentration of the organic solvent is lower than that at the extreme value point and in the region where the concentration of the organic solvent is higher than that at the extreme value point. Therefore, in such a nonlinear calibration curve, there are regions where it is difficult to estimate the concentration of the organic solvent with good accuracy from the measured physical property.

[0009] However, with the above configuration, the first physical property value P1 at the first time point and the second physical property value P2 at the second time point, a small time interval after the first time point, are measured, and the difference ΔP is calculated. Furthermore, the calibration curve portion to which the first physical property value P1 or the second physical property value P2 belongs is identified from the sign of ΔP. Here, the calibration curve portion is identified as either the concentration region lower than the concentration of the organic solvent at the extreme point of the calibration curve, or the concentration region higher than the concentration of the organic solvent at the extreme point of the calibration curve. After identifying the calibration curve portion, the concentration of the organic solvent at the first or second time point is estimated. In other words, with the above configuration, even when using a nonlinear calibration curve with extreme points, the concentration of the organic solvent can be estimated with good accuracy, and the organic solvent can be effectively concentrated and recovered.

[0010] In the above configuration, the extreme value point is the maximum point at which the physical property value is maximized, and the concentration estimation step may be to estimate the concentration of the organic solvent at the first or second time point in the portion of the calibration curve where the concentration is lower than the concentration of the organic solvent at the extreme value when ΔP(P1-P2) is a negative value, and to estimate the concentration of the organic solvent at the first or second time point in the portion of the calibration curve where the concentration is higher than the concentration of the organic solvent at the extreme value when ΔP(P1-P2) is a positive value.

[0011] Furthermore, in the above configuration, the extreme value point is the maximum point at which the physical property value is maximized, and the concentration estimation step may be to estimate the concentration of the organic solvent at the first or second time point in the portion of the calibration curve where the concentration is lower than the concentration of the organic solvent at the maximum point when ΔP(P2-P1) is a positive value, and to estimate the concentration of the organic solvent at the first or second time point in the portion of the calibration curve where the concentration is higher than the concentration of the organic solvent at the maximum point when ΔP(P2-P1) is a negative value.

[0012] Furthermore, the above configuration preferably includes a separation step in which the liquid to be treated is circulated and the water is continuously or intermittently separated by membrane, and the separation step is performed while controlling the separation conditions based on the concentration of the organic solvent estimated in the concentration estimation step. As mentioned above, in a nonlinear calibration curve with one maximum point, there are regions where it is difficult to estimate the concentration of the organic solvent. However, with the organic solvent recovery method of the present invention, even in such regions, the concentration of the organic solvent can be estimated with high accuracy based on the physical properties of the liquid to be treated measured, and consequently, the accuracy of controlling the separation conditions can also be improved. As a result, according to the above configuration, water can be separated and removed more efficiently, and the organic solvent can be concentrated and recovered more effectively.

[0013] Furthermore, the above configuration preferably includes a temperature adjustment step that adjusts the temperature of the liquid to be treated immediately before membrane separation in the separation step. By adjusting the temperature of the liquid to be treated immediately before membrane separation in the temperature adjustment step, the separation performance in membrane separation can be improved. This allows for more efficient separation and removal of water, and more effectively concentration and recovery of organic solvents.

[0014] The organic solvent recovery apparatus of the present invention, in order to solve the above problems, is an organic solvent recovery apparatus that separates water from a liquid to be treated containing an organic solvent and water, concentrates and recovers the organic solvent, and includes a storage unit that stores information of a nonlinear calibration curve that shows the relationship between the concentration of the organic solvent in the liquid to be treated and predetermined physical properties of the liquid to be treated, and has one extreme point where the physical properties are at their maximum or minimum; a physical property measurement unit that measures the physical properties at minute time intervals in the liquid to be treated from which the water has been continuously separated; and a first physical property P1 measured at a first time point in the physical property measurement unit, and The system comprises: a calculation unit that calculates the difference ΔP between a second physical property value P2 measured at a second time point after a minute interval from a first time point; an identification unit that identifies a calibration curve portion to which the first physical property value P1 or the second physical property value P2 belongs based on the sign of ΔP; and a concentration estimation unit that estimates the concentration of the organic solvent at the first time point or the second time point after the identification unit has identified the calibration curve portion, wherein the calibration curve portion is a portion of the concentration region where the concentration of the organic solvent is lower than the concentration of the organic solvent at the extreme point of the calibration curve, or a portion of the concentration region where the concentration of the organic solvent is higher than the concentration of the organic solvent at the extreme point of the calibration curve.

[0015] As described above, in a nonlinear calibration curve showing the relationship between the concentration of the organic solvent in the liquid being treated and a predetermined physical property of the liquid being treated, if there is an extreme value point where the physical property is either extremely large or extremely small, there is a region where it is difficult to estimate the concentration of the organic solvent with good accuracy from the measured physical property. However, with the above configuration, the physical property measurement unit measures the first physical property P1 at the first time point and the second physical property P2 at the second time point, a small amount of time after the first time point, and the calculation unit calculates the difference ΔP. Furthermore, the identification unit identifies, from the sign of ΔP, either the region of the calibration curve to which the first physical property P1 or the second physical property P2 belongs, which is a concentration region lower than the concentration of the organic solvent at the extreme value point of the calibration curve, or the region of the calibration curve to which the concentration of the organic solvent at the extreme value point of the calibration curve is higher. After identifying the calibration curve region, the concentration estimation unit estimates the concentration of the organic solvent at the first or second time point. In other words, with the above configuration, even if the calibration curve stored in the storage unit is nonlinear and has a maximum point, the concentration of the organic solvent can be estimated with good accuracy, and the organic solvent can be effectively concentrated and recovered.

[0016] In the above configuration, the extreme value point is the maximum value point where the physical property value is at its maximum, and the concentration estimation unit may, when ΔP(P1-P2) is a negative value, estimate the concentration of the organic solvent at the first or second time point in the portion of the calibration curve where the concentration is lower than the concentration of the organic solvent at the extreme value, and when ΔP(P1-P2) is a positive value, estimate the concentration of the organic solvent at the first or second time point in the portion of the calibration curve where the concentration is higher than the concentration of the organic solvent at the extreme value.

[0017] Furthermore, in the above configuration, the extreme value point is the maximum point where the physical property value reaches its maximum, The concentration estimation unit may, when ΔP(P2-P1) is a positive value, estimate the concentration of the organic solvent at the first or second time point in the portion of the calibration curve where the concentration is lower than the concentration of the organic solvent at the maximum point, and when ΔP(P2-P1) is a negative value, estimate the concentration of the organic solvent at the first or second time point in the portion of the calibration curve where the concentration is higher than the concentration of the organic solvent at the maximum point.

[0018] In the above configuration, it is preferable that the separation unit circulates the liquid to be treated and performs membrane separation of the water continuously or intermittently, and that the separation unit performs membrane separation while controlling the separation conditions based on the concentration of the organic solvent estimated by the concentration estimation unit. As mentioned above, in a nonlinear calibration curve with one maximum point, there is a region where it is difficult to estimate the concentration of the organic solvent. However, with the organic solvent recovery device of the present invention, even in such a region, the concentration of the organic solvent can be estimated with high accuracy based on the physical properties of the liquid to be treated measured, and consequently, the accuracy of controlling the separation conditions can also be improved. As a result, with the above configuration, water can be separated and removed more efficiently, and the organic solvent can be concentrated and recovered more effectively.

[0019] Furthermore, in the above configuration, it is preferable to include a temperature control unit that adjusts the temperature of the liquid to be treated immediately before membrane separation in the separation unit. By adjusting the temperature of the liquid to be treated immediately before membrane separation, the separation performance in membrane separation can be improved. This allows for more efficient separation and removal of water, and more effectively concentration and recovery of organic solvents. [Effects of the Invention]

[0020] According to the present invention, even when a calibration curve indicating the relationship between the concentration of an organic solvent in a liquid to be treated and a predetermined physical property value of the liquid to be treated has one maximum point at which the physical property value reaches a maximum, the concentration of the organic solvent can be estimated accurately. This enables effective separation of water from the liquid to be treated and efficient recovery of organic solvents such as IPA. As a result, it is possible to provide an organic solvent recovery method and an organic solvent recovery apparatus that can reduce the disposal amount of organic solvents and reduce environmental load. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] [Figure 1] FIG. 1 is a plan view showing a schematic configuration of a substrate processing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory view schematically showing a substrate processing unit in the substrate processing apparatus according to the embodiment of the present invention. [Figure 3] FIG. 3 is an explanatory view schematically showing a concentration and recovery unit in the substrate processing apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram showing a hardware configuration of a control unit in the substrate processing apparatus according to the embodiment of the present invention. [Figure 5] FIG. 5 is a block diagram showing an example of a functional configuration of a control unit in the substrate processing apparatus according to the embodiment of the present invention. [Figure 6] FIG. 6 is a graph conceptually showing a calibration curve indicating the relationship between the concentration of an organic solvent in a liquid to be treated and the physical property value of the liquid to be treated. [Figure 7] FIG. 7 is a flow diagram for explaining an organic solvent recovery method according to an embodiment of the present invention. [Figure 8] FIGS. 8(a) to 8(c) are graphs showing calibration curves indicating the relationship between the ultrasonic propagation velocity (m / s) and the IPA concentration (wt%) at each liquid temperature of a mixed liquid of IPA and water. DETAILED DESCRIPTION OF THE INVENTION

[0022] (Substrate Processing Apparatus) A substrate processing apparatus according to an embodiment of the present invention will be described below with reference to Figure 1. Figure 1 is a plan view showing the schematic configuration of the substrate processing apparatus 100 according to this embodiment. The substrate processing apparatus 100 of this embodiment is a single-wafer type substrate processing apparatus used for various substrate processing tasks such as rinsing using a rinsing solution and replacement processing with a processing solution after rinsing.

[0023] In this specification, "substrate" refers to various types of substrates, including semiconductor substrates, photomask glass substrates, liquid crystal display glass substrates, plasma display glass substrates, FED (Field Emission Display) substrates, optical disc substrates, magnetic disc substrates, and magneto-optical disc substrates. In this specification, "pattern-forming surface" refers to any surface on a substrate, whether planar, curved, or uneven, where an uneven pattern is formed in any area. In this specification, a substrate is given as an example in which a circuit pattern, etc. (hereinafter referred to as "pattern") is formed only on one main surface. Here, the pattern-forming surface (main surface) on which the pattern is formed is referred to as the "surface."

[0024] As shown in Figure 1, the substrate processing apparatus 100 includes a substrate processing unit 110 that performs various processes on the substrate W, an indexer unit 120, and a control unit 130 that controls the substrate processing apparatus 100.

[0025] <Indexer section> The indexer unit 120 has the function of supplying substrates W to the substrate processing unit 110 or retrieving substrates W from the substrate processing unit 110. Specifically, the indexer unit 120 is equipped with four container holding units 121, and each container holding unit 121 is provided with one container C. Examples of container C include FOUP (Front Opening Unified Pod), SMIF (Standard Mechanical Interface) pod, and OC (Open Cassette), which contain multiple substrates W in a sealed state. In this embodiment, the case where there are four container holding units 121 is described as an example, but the present invention is not limited to this. There may be multiple container holding units 121.

[0026] The indexer unit 120 further includes a first transport unit 122 for transporting substrates W. The first transport unit 122 is provided between the container holding unit 121 and the substrate processing unit 110. The first transport unit 122 includes a base unit 122a fixed to the apparatus housing, a multi-joint arm 122b rotatably mounted on the base unit 122a around a vertical axis, and a hand 122c attached to the tip of the multi-joint arm 122b. The hand 122c is structured to hold substrates W on its upper surface. The first transport unit 122 can access the container C held by the container holding unit 121 to remove unprocessed substrates W from the container C or store processed substrates W in the container C.

[0027] <Circuit board processing> The substrate processing unit 110 performs a rinsing treatment on the substrate W using a rinse solution consisting of water, and a replacement treatment to replace the rinse solution remaining on the surface Wf of the substrate W with a processing solution containing an organic solvent. The substrate processing unit 110 comprises a second transport unit 111 located approximately in the center in a plan view, four substrate processing units 1 arranged to surround the second transport unit 111, and a concentration and recovery unit 2 as an organic solvent recovery device that concentrates and recovers organic solvents from the wastewater discharged by the substrate processing units 1.

[0028] 1. Second Conveyor Unit For example, a substrate transport robot can be used as the second transport unit 111. The second transport unit 111 randomly accesses each substrate processing unit 1 and delivers the substrates W. The substrate processing unit 110 is equipped with multiple substrate processing units 1 and concentration and recovery units 2, enabling parallel processing of multiple substrates W. The second transport unit 111 may also be called a center robot.

[0029] 2. PCB Processing Unit Next, the configuration of the substrate processing unit 1 in the substrate processing unit 110 will be described below with reference to Figure 2. Figure 2 is a schematic explanatory diagram showing the substrate processing unit 1 in the substrate processing apparatus of this embodiment. In Figure 2, XYZ orthogonal coordinate axes are displayed as appropriate to clarify the directional relationships of the illustrated objects. In this figure, the XY plane represents the horizontal plane, and the +Z direction represents the vertically upward direction.

[0030] The substrate processing unit 1 comprises at least a chamber 11 which is a container for housing the substrate W, a substrate holding section 12 which holds the substrate W, a supply section 13 which supplies processing liquid to the substrate W held in the substrate holding section 12, and a splash prevention cup 14 which collects rinse liquid, processing liquid, etc. that are supplied to the substrate W held in the substrate holding section 12 and discharged to the outside of the peripheral edge of the substrate W.

[0031] The substrate holding unit 12 comprises a rotation drive unit 12a, a spin base 12b, and chuck pins 12c. The spin base 12b has a planar size slightly larger than the substrate W. Multiple chuck pins 12c are erected near the periphery of the spin base 12b to grip the periphery of the substrate W. The number of chuck pins 12c is not particularly limited, but it is preferable to provide at least three or more in order to reliably hold the circular substrate W. In this embodiment, three are arranged at equal intervals along the periphery of the spin base 12b. Each chuck pin 12c comprises a substrate support pin that supports the periphery of the substrate W from below, and a substrate holding pin that presses against the outer peripheral end face of the substrate W supported by the substrate support pin to hold the substrate W.

[0032] The spin base 12b is connected to the rotary drive unit 12a. The rotary drive unit 12a rotates around axis A along the Z direction according to the operation command of the control unit 130. The rotary drive unit 12a is composed of a known belt, motor, and rotating shaft. When the rotary drive unit 12a rotates around axis A, the substrate W, which is held above the spin base 12b by the chuck pin 12c, rotates together with the spin base 12b around a rotation axis parallel to the vertical direction of the surface Wf of the substrate W, i.e., around axis A.

[0033] Next, the supply unit 13 will be described. The supply unit 13 is a unit that supplies water such as DIW and a processing liquid for replacing residual water onto the pattern formation surface of the substrate W. Examples of processing liquids include organic solvents such as IPA.

[0034] As shown in Figure 2, the supply unit 13 includes at least a nozzle 13a, a supply pipe 13b, an organic solvent supply unit 13c, and a water supply unit 13d.

[0035] The nozzle 13a is connected via a pipeline to a supply pipe 13b to which the processing liquid is supplied, and can discharge the processing liquid or water (hereinafter referred to as "processing liquid, etc.") onto the surface Wf of the substrate W. The nozzle 13a is attached to the tip of a horizontally extending arm (not shown). The arm is rotatable under the control of the control unit 130, and the nozzle 13a moves along with the rotation of the arm. When the processing liquid, etc. is not being discharged, the nozzle 13a is positioned in a retracted position outside the peripheral edge of the substrate W and outside the splash prevention cup 14. When the processing liquid, etc. is being discharged, the nozzle 13a is positioned above the spin base 12b, that is, above the center of the surface Wf of the substrate W (axis A or its vicinity), as the arm rotates according to the operation command of the control unit 130.

[0036] A valve 131 is provided along the supply pipe 13b. The valve 131 is electrically connected to the control unit 130 and is normally closed. The opening and closing of the valve 131 is controlled by an operation command from the control unit 130. When the valve 131 is opened by an operation command from the control unit 130, the processing liquid, etc., is supplied through the supply pipe 13b to the surface Wf of the substrate W from the nozzle 13a.

[0037] The organic solvent supply unit 13c can supply unused or reused organic solvent onto the surface Wf of the substrate W via the supply pipe 13b and nozzle 13a. The organic solvent supply unit 13c comprises an organic solvent supply pipe 132 and an organic solvent storage unit 133. The organic solvent storage unit 133 is connected to the upstream side of the organic solvent supply pipe 132, and the downstream side communicates with the supply pipe 13b. In addition, a pump 134, a flow rate adjustment valve 135, and a valve 136 are sequentially provided along the path of the organic solvent supply pipe 132 from the upstream side to the downstream side. The organic solvent storage unit 133 has, for example, a tank capable of storing liquid. Unused or reused organic solvent is stored in this tank. The pump 134 is controlled by an operation command from the control unit 130 and can send the organic solvent stored in the organic solvent storage unit 133 to the supply pipe 13b. The flow rate adjustment valve 135 can adjust the flow rate of the organic solvent supplied from the organic solvent storage unit 133 by the operation of the pump 134. Valve 136 is electrically connected to the control unit 130 and is normally closed. The opening and closing of valve 136 is controlled by an operation command from the control unit 130. When valve 136 is opened by an operation command from the control unit 130, the organic solvent is supplied to the supply pipe 13b through the organic solvent supply pipe 132.

[0038] The water supply unit 13d can supply unused water onto the surface Wf of the substrate W via the supply pipe 13b and nozzle 13a. The water supply unit 13d comprises a water supply pipe 137 and a water storage unit 138. For example, the water storage unit 138 has a tank capable of storing liquid. The water storage unit 138 is connected to the upstream side of the water supply pipe 137, and the downstream side communicates with the supply pipe 13b. In addition, a pump 139, a flow control valve 140, and a valve 141 are sequentially provided along the path of the water supply pipe 137 from the upstream side to the downstream side. The water storage unit 138 has, for example, a tank capable of storing liquid. Unused water is stored in this tank. The pump 139 is controlled by an operation command from the control unit 130 and can send the unused water stored in the water storage unit 138 to the supply pipe 13b. Furthermore, the flow rate adjustment valve 140 can adjust the flow rate of unused water supplied from the water storage section 138 by the operation of the pump 139. Valve 141 is electrically connected to the control unit 130 and is normally closed. The opening and closing of valve 141 is controlled by an operation command from the control unit 130. When valve 141 is opened by an operation command from the control unit 130, unused water is supplied to the supply pipe 13b through the water supply pipe 137.

[0039] The splash-proof cup 14 is positioned to surround the spin base 12b. The splash-proof cup 14 is connected to a lifting drive mechanism (not shown) and is capable of moving up and down in the Z direction as shown in Figure 2. When supplying water or processing liquid to the surface Wf of the substrate W, the splash-proof cup 14 is positioned by the lifting drive mechanism to a predetermined position as shown in Figure 2, surrounding the substrate W, which is held by the chuck pin 12c, from a lateral position. This allows for the collection of liquids such as water and processing liquid that splash from the substrate W and the spin base 12b.

[0040] 3. Concentration and Recovery Unit Next, the configuration of the concentration and recovery unit 2 in the substrate processing unit 110 will be described below with reference to Figure 3. Figure 3 is a schematic diagram illustrating the concentration and recovery unit 2 in the substrate processing apparatus of this embodiment.

[0041] The concentration and recovery unit 2 recovers the treatment liquid used to remove water remaining on the surface Wf of the substrate W, and separates and removes at least a portion of the water from the recovered wastewater treatment liquid (hereinafter referred to as "treated liquid") to make it reusable. Specifically, as shown in Figure 3, the concentration and recovery unit 2 comprises at least a recovery pipe 21, a treated liquid storage section 22, a temperature control section 23, a separation section 24, a circulation path 25, a separated liquid discharge pipe 26, and a water discharge pipe 27.

[0042] The recovery pipe 21 supplies the liquid to be treated, discharged from the splash-proof cup 14, to the liquid to be treated storage section 22. One end of the recovery pipe 21 is connected to the splash-proof cup 14, and the other end is connected to the liquid to be treated storage section 22. A valve 21a is provided along the path of the recovery pipe 21. The valve 21a is electrically connected to the control unit 130 and is normally closed. The opening and closing of the valve 21a is controlled by an operation command from the control unit 130. When the valve 21a is opened by an operation command from the control unit 130, the liquid to be treated collected in the splash-proof cup 14 is supplied to the liquid to be treated storage section 22 through the recovery pipe 21.

[0043] The liquid to be treated storage section 22 can store the liquid to be treated that is discharged from the splash prevention cup 14 and supplied by the recovery pipe 21. The liquid to be treated storage section 22 is, for example, a tank. One end and the other end of a circulation path 25, which has a separation section 24 in the middle of its path, are connected to this liquid to be treated storage section 22. Therefore, the liquid to be treated storage section 22 can also store the separated liquid obtained when water is separated and removed from the liquid to be treated in the separation section 24.

[0044] The temperature control unit 23 can adjust the temperature of the liquid to be treated supplied to the separation unit 24. The temperature control unit 23 is electrically connected to the control unit 130 and adjusts the temperature of the liquid to be treated in accordance with operation commands from the control unit 130. This improves the separation performance of the zeolite membrane, for example, when a zeolite membrane is used as the separation membrane in the separation unit 24, which will be described later. The temperature of the liquid to be treated supplied to the separation unit 24 is preferably in the range of 25°C (RT) to 80°C, more preferably in the range of 50°C to 80°C, and even more preferably in the range of 70°C to 80°C, for example, when separating IPA and water in the liquid to be treated without vaporizing them. The temperature control unit 23 is not particularly limited, and known temperature control mechanisms such as a Peltier element or piping through temperature-controlled water can be used.

[0045] The separation unit 24 can separate and remove at least a portion of the water contained in the liquid to be treated. Examples of separation membranes used in the separation unit 24 include dehydration membranes that allow water to permeate but prevent organic solvents such as IPA from permeating. The separation membrane may also be a polymer membrane made of polymer materials such as polyvinyl alcohol, chitosan, and polyimide, or a carbon nanotube separation membrane, or any other type of membrane. Specific examples of separation membranes include zeolite membranes formed from zeolites, as mentioned above.

[0046] As described above, the circulation path 25 is provided with a separation unit 24, which allows at least a portion of the water contained in the liquid to be treated to be separated and the resulting separated liquid to be returned to the liquid to be treated storage unit 22. Along the route of the circulation path 25, downstream of the liquid to be treated storage unit 22 and upstream of the separation unit 24, valves 25a and pumps 25b are sequentially provided. Also along the route of the circulation path 25, upstream of the liquid to be treated storage unit 22 and downstream of the separation unit 24, valve 25c is provided.

[0047] Valve 25a is electrically connected to the control unit 130 and is normally closed. The opening and closing of valve 25a is controlled by an operation command from the control unit 130. When valve 25a is opened by an operation command from the control unit 130, the liquid to be treated stored in the liquid to be treated storage unit 22 is supplied to the separation unit 24 through the circulation path 25. Pump 25b is controlled by an operation command from the control unit 130 and can circulate the liquid to be treated stored in the liquid to be treated storage unit 22 through the circulation path 25. Valve 25c is electrically connected to the control unit 130 and is normally closed. The opening and closing of valve 25c is controlled by an operation command from the control unit 130. When valve 25c is opened by an operation command from the control unit 130, the separated liquid separated in the separation unit 24 is supplied to the liquid to be treated storage unit 22 through the circulation path 25.

[0048] Furthermore, along the circulation path 25, a flow sensor 25d is provided between valve 25a and pump 25b, a pressure sensor 25e (e.g., diaphragm type) is provided between pump 25b and temperature control unit 23, a temperature sensor 25f is provided between temperature control unit 23 and separation unit 24, and a physical property measurement unit 25g is provided between separation unit 24 and valve 25c. The flow sensor 25d measures the flow rate of the liquid to be treated in the circulation path 25 supplied to the temperature control unit 23. The measured flow rate value of the liquid to be treated is input to the control unit 130. The pressure sensor 25e measures the pressure of the liquid to be treated in the circulation path 25 sent by pump 25b. The measured pressure value of the liquid to be treated is input to the control unit 130. The temperature sensor 25f measures the temperature of the liquid to be treated immediately before it is supplied to the separation unit 24, after its temperature has been adjusted by the temperature control unit 23. As the temperature sensor 25f, for example, a thermocouple or thermistor can be used. The measured temperature value of the liquid to be treated is input to the control unit 130. The physical property measurement unit 25g measures the physical properties of the separated liquid in the circulation path 25 after water has been separated and removed from the liquid to be treated in the separation unit 24. Examples of physical properties to be measured include the ultrasonic propagation velocity, refractive index, or density of the separated liquid. The physical property measurement unit 25g can be appropriately selected according to the physical properties to be measured, and specifically, examples include an ultrasonic sound velocity measuring device capable of measuring ultrasonic propagation velocity, a refractometer, or a liquid density measuring device. The measured physical properties are input to the control unit 130. The measured physical properties are used by the control unit 130 to estimate the concentration of the organic solvent in the separated liquid using a calibration curve (the estimation of the organic solvent concentration will be described in detail later).

[0049] The separated liquid discharge pipe 26 is located in the middle of the circulation path 25, branching off between the separation unit 24 and the temperature sensor 25f. A three-way valve 25h is provided at the branching point where the separated liquid discharge pipe 26 branches off from the circulation path 25. This allows the flow path of the separated liquid flowing through the circulation path 25 to be changed to the separated liquid discharge pipe 26. As a result, the separated liquid, in which water is separated and removed in the separation unit 24 while circulating in the circulation path 25, and the organic solvent is concentrated to a certain level or higher, can be discharged from the separated liquid discharge pipe 26. The three-way valve 25h is electrically connected to the control unit 130, and the change in flow path by the three-way valve 25h is controlled by the operation command of the control unit 130. The separated liquid discharged from the separated liquid discharge pipe 26 can be reused as a processed liquid. A filter may also be provided in the middle of the path of the separated liquid discharge pipe 26. This allows for the further separation and removal of impurities such as particles and metal ions from the separated liquid whose organic solvent concentration exceeds a predetermined value.

[0050] The water discharge pipe 27 is connected to the separation unit 24 and discharges the water separated from the liquid to be treated in the separation unit 24. A valve 27a is provided along the path of the water discharge pipe 27. The valve 27a is electrically connected to the control unit 130 and is normally closed. The opening and closing of the valve 27a is controlled by an operation command from the control unit 130. When the valve 27a is opened by an operation command from the control unit 130, the water separated in the separation unit 24 is discharged through the water discharge pipe 27.

[0051] <Department Head> The control unit 130 is electrically connected to each part of the substrate processing apparatus 100 and controls the operation of each part. As shown in Figure 4, the hardware configuration of the control unit 130 includes a CPU (Central Processing Unit) 151, which is an arithmetic processing unit that performs various calculations; a ROM (Read Only Memory) 152, which is a read-only memory that stores the substrate processing program; a RAM (Random Access Memory) 153, which is a read-write memory that stores various information; and a storage device 154 that stores control software and data. Figure 4 is a block diagram showing the hardware configuration of the control unit 130. The storage device 154 pre-stores substrate processing condition information (processing recipe) according to the substrate W, control condition information for controlling the substrate processing apparatus 100, and so on. The storage device 154 also pre-stores information on organic solvent recovery conditions for separating water from the liquid to be processed and concentrating and recovering the organic solvent, and information on a calibration curve that shows the relationship between the concentration of the organic solvent in the liquid to be processed and predetermined physical properties of the liquid to be processed. The CPU 151 reads information such as substrate processing conditions, control conditions, organic solvent recovery conditions, and calibration curves into the RAM 153 and controls each part of the substrate processing apparatus 100 according to its contents.

[0052] Furthermore, the control unit 130, in terms of functional concept, includes a storage unit 155, a calculation unit 156, a specific unit 157, and a concentration estimation unit 158, as shown in Figure 5. Figure 5 is a block diagram showing an example of the functional configuration of the control unit 130.

[0053] The memory unit 155 stores information on a nonlinear calibration curve that shows the relationship between the concentration of the organic solvent in the liquid to be treated and a predetermined physical property value of the liquid to be treated. As a nonlinear calibration curve, for example, one having a single maximum point Q where the physical property value of the liquid to be treated is at its maximum is used, as shown in Figure 6. Figure 6 is a graph that conceptually represents a calibration curve showing the relationship between the concentration of the organic solvent in the liquid to be treated and the physical property value of the liquid to be treated. In such a nonlinear calibration curve, there is a portion of the calibration curve, such as region X, where, for example, if the physical property value of the liquid to be treated is P, it can be easily estimated that the concentration of the organic solvent is C. On the other hand, there is a portion of the calibration curve, such as region Y, where the concentration of the organic solvent can be converted in both the calibration curve portion in the concentration range lower than the concentration of the organic solvent at the maximum point Q (the curve portion between two points A and Q) and the calibration curve portion in the concentration range higher than the concentration of the organic solvent at the maximum point Q (the curve portion between two points Q and B). For example, if the physical property of the liquid being treated is P', the concentration of the organic solvent can be converted to both C' and C'' in the calibration curve portion in region Y. Therefore, in a nonlinear calibration curve as shown in Figure 6, there is a single maximum point Q where the physical property of the liquid being treated is at its maximum, resulting in a portion of the calibration curve where it is difficult to accurately estimate the concentration of the organic solvent using conventional methods. Furthermore, if the physical property of the liquid being treated is temperature-dependent, the calibration curve information stored in the memory unit 155 may include information on the calibration curve showing the relationship between the concentration of the organic solvent and the physical property of the liquid being treated at each liquid temperature.

[0054] The calculation unit 156 calculates the difference between the physical properties measured at minute time intervals in the physical property measurement unit 25g. Specifically, the calculation unit 156 calculates the difference ΔP(P1-P2) between the first physical property P1 measured at the first time point and the second physical property P2 measured at the second time point, a minute time after the first time point (see Figure 6). The minute time interval is preferably 60 seconds or less, more preferably 10 seconds or less, and particularly preferably 1 second or less.

[0055] The identification unit 157 retrieves calibration curve information stored in the memory unit 155, which shows the relationship between the concentration of the organic solvent in the liquid to be treated and predetermined physical properties of the liquid to be treated. Based on the positive or negative sign of ΔP, it identifies the calibration curve portion to which the first physical property P1 or the second physical property P2 belongs. For example, if ΔP is a negative value, it identifies the calibration curve portion in the concentration region lower than the concentration of the organic solvent at the maximum point (in Figure 6, the curve portion between points A and Q). If ΔP is a positive value, it identifies the calibration curve portion in the concentration region higher than the concentration of the organic solvent at the maximum point (in Figure 6, the curve portion between points Q and B).

[0056] The concentration estimation unit 158 ​​estimates the concentration of the organic solvent at the first or second time point in the calibration curve portion identified by the identification unit 157. For example, if the identification unit 157 identifies a calibration curve portion in a concentration region lower than the concentration of the organic solvent at the maximum point (in Figure 6, the curve portion between points A and Q), the concentration of the organic solvent at the first or second time point is estimated in that calibration curve portion. Also, if the identification unit 157 identifies a calibration curve portion in a concentration region higher than the concentration of the organic solvent at the maximum point (in Figure 6, the curve portion between points Q and B), the concentration of the organic solvent at the first or second time point is estimated in that calibration curve portion. With this method of estimating the concentration of the organic solvent, the concentration of the organic solvent in the separated liquid can be accurately estimated even in the case of a nonlinear calibration curve that has a region (region Y) where concentration conversion is not possible, as shown in Figure 6. As a result, the concentration of the organic solvent by separating and removing water from the liquid to be treated can be efficiently performed.

[0057] (Substrate processing method) Next, a method for recovering organic solvents using the substrate processing apparatus 100 of this embodiment will be described below. The organic solvent recovery method according to this embodiment can recover a processing liquid containing an organic solvent used to remove a rinse solution consisting of water, such as DIW, remaining on the surface Wf of a substrate W, and concentrate the organic solvent by separating and removing water from the recovered processing liquid (processed liquid). This reduces the amount of organic solvent waste and reduces the environmental burden in this embodiment. As shown in Figure 7, the organic solvent recovery method of this embodiment includes a recovery step S1 for recovering the processing liquid as wastewater after substrate processing, a temperature adjustment step S2 for adjusting the temperature of the recovered processing liquid (processed liquid), a separation step S3 for separating and removing at least a portion of the water from the processed liquid, a calibration curve preparation step S4 for preparing a nonlinear calibration curve, a physical property measurement step S5 for measuring the physical properties of the separated liquid obtained in the separation step S3 at minute time intervals, a calculation step S6 for calculating the difference in physical properties measured at minute time intervals, a identification step S7 for identifying the calibration curve portion from the sign of the difference in physical properties, and a concentration estimation step S8 for measuring the concentration of the organic solvent in the separated liquid using the calibration curve based on the difference in physical properties. Figure 7 is a flowchart illustrating the organic solvent recovery method according to this embodiment.

[0058] The recovery process S1 is a process of discharging and recovering the processing liquid used for substrate processing on the surface Wf of the substrate W from the substrate processing unit 1. When the valve 21a is opened by an operation command from the control unit 130, the processing liquid collected in the splash-proof cup 14 is discharged as wastewater through the recovery pipe 21 connected to the splash-proof cup 14. The wastewater discharged through the recovery pipe 21 is stored in the treated liquid storage section 22 as the treated liquid.

[0059] The temperature adjustment step S2 is a process in which the temperature of the liquid to be treated circulating in the circulation path 25 is adjusted by a temperature adjustment unit 23 provided in the middle of the circulation path 25, based on an operation command from the control unit 130. When valves 25a, 25c, and 27a are opened by an operation command from the control unit 130, the liquid to be treated stored in the liquid to be treated storage unit 22 is released by the operation of the pump 25b and circulates in the circulation path 25. The liquid to be treated flowing in the circulation path 25 is heated to a predetermined temperature by the temperature adjustment unit 23 provided in the middle of the circulation path 25, based on an operation command from the control unit 130. For example, when a zeolite membrane is used as the separation membrane of the separation unit 24, the separation performance of the zeolite membrane can be improved by heating the liquid to be treated just before it is supplied to the separation unit 24. Furthermore, the three-way valve 25h, located at the point where the separated liquid discharge pipe 26 branches off from the circulation path 25, is controlled by the control unit 130 to prevent communication between the circulation path 25 and the separated liquid discharge pipe 26 when the liquid to be treated is circulated within the circulation path 25. In addition, it is preferable that the valve 21a, located along the path of the recovery pipe 21, is closed when the liquid to be treated is circulated within the circulation path 25.

[0060] The separation step S3 is a step in which at least a portion of the water is continuously or intermittently separated and removed from the liquid to be treated circulating in the circulation path 25 to produce a separated liquid. The liquid to be treated, which has been heated in the temperature control unit 23, has at least a portion of the water contained in it separated and removed in the separation unit 24, which is provided along the path of the circulation path 25. The liquid to be treated from which at least a portion of the water has been removed in the separation unit 24 is discharged as a separated liquid in which the organic solvent is concentrated and is stored again in the liquid to be treated storage unit 22. In addition, by issuing an operation command to the valve 27a to open it, the water separated from the liquid to be treated in the separation unit 24 can be discharged from the water discharge pipe 27.

[0061] The calibration curve preparation step S4 is a step in which information for a nonlinear calibration curve showing the relationship between the concentration of the organic solvent in the liquid to be treated and a predetermined physical property of the liquid to be treated is prepared. Specifically, this step is a step in which the control unit 130 stores the calibration curve information in the storage unit 155. The calibration curve used has one maximum point where the physical property of the liquid to be treated is at its maximum. Furthermore, if the physical property of the liquid to be treated is temperature-dependent, the calibration curve information includes information for a calibration curve showing the relationship between the concentration of the organic solvent and the physical property of the liquid to be treated for each liquid temperature of the liquid to be treated. As mentioned above, examples of physical properties of the liquid to be treated include ultrasonic propagation velocity, refractive index, or density. For example, if the liquid to be treated is a mixture of IPA as an organic solvent and water, and ultrasonic propagation velocity is used as the physical property of the liquid to be treated, the calibration curve showing the relationship between the ultrasonic propagation velocity and the concentration of IPA in the liquid to be treated is shown in Figures 8(a) to 8(c). Figures 8(a) to 8(c) are graphs showing calibration curves illustrating the relationship between the ultrasonic propagation velocity (m / s) and the concentration (wt%) of IPA at various liquid temperatures in a mixture of IPA and water. As shown in Figure 8(a), the calibration curve for IPA at each liquid temperature exhibits a single maximum point where the ultrasonic propagation velocity is at its highest.

[0062] The physical property measurement step S5 is a step in which the physical properties of the separated liquid in the circulation path 25 discharged from the separation unit 24 are measured using the physical property measurement unit 25g. The measurement of the physical properties of the liquid to be processed is performed continuously at minute intervals. For example, first, the first physical property P1 at the first time point of the separated liquid is measured, and then the second physical property P2 at the second time point, a minute time after the first time point, is measured, and so on, continuously by the physical property measurement unit 25g. The measured first physical property P1 and second physical property P2 are input to the control unit 130.

[0063] The calculation step S6 is a step in which the difference ΔP(P1-P2) is calculated based on the first physical property value P1 and the second physical property value P2 measured in the physical property value measurement step S5. That is, the calculation unit 156 of the control unit 130 calculates ΔP using the first physical property value P1 and the second physical property value P2 measured by the physical property value measurement unit 25g and input to the control unit 130. Since the measurement of physical properties in the physical property value measurement step S5 is performed continuously at minute intervals, the calculation of ΔP may also be performed continuously.

[0064] The identification step S7 is a step in which the calibration curve portion to which the first physical property value P1 or the second physical property value P2 belongs is identified using the first physical property value P1 and the second physical property value P2 measured in the physical property value measurement step S5, and the difference ΔP calculated in the calculation step S6. In this embodiment, the organic solvent recovery method concentrates the organic solvent by continuously or intermittently removing water while circulating the liquid to be treated, so the concentration of the organic solvent in the separated liquid increases irreversibly over time. Therefore, ΔP, which is the amount of change in the physical property value (derivative value) for every minute time interval calculated in the calculation step S6, shows a clear difference near the maximum point Q on the calibration curve.

[0065] In this process, first, the concentration estimation unit 158 ​​of the control unit 130 reads the calibration curve information stored in the memory unit 155. If the physical property value is temperature-dependent, the calibration curve information for the temperature corresponding to the liquid temperature measured by the temperature sensor 25f is read. Then, for example, if the ΔP calculated in calculation step S6 is a negative value, it is determined that the concentration of the organic solvent at the first physical property value P1 at the first time point or the second physical property value P2 at the second time point is lower than the concentration of the organic solvent at the maximum point Q where the physical property value is maximum (see Figure 6). The concentration of the organic solvent at the first physical property value P1 at the first time point or the second physical property value P2 at the second time point is identified as belonging to the calibration curve portion (the curve portion between points A and Q) in the concentration range lower than the concentration of the organic solvent at the maximum point Q. On the other hand, if ΔP is a positive value, it is determined that the concentration of the organic solvent at the first physical property value P1 at the first time point or the second physical property value P2 at the second time point is higher than the concentration of the organic solvent at the maximum point Q where the physical property value is maximum (see Figure 6). Then, it is determined that the concentration of the organic solvent at the first physical property value P1 at the first time point or the second physical property value P2 at the second time point belongs to the calibration curve portion (the curve portion between points Q and B) in the concentration range where the concentration of the organic solvent is higher than the concentration at the maximum point Q.

[0066] The concentration estimation step S8 is a step in which the concentration of the organic solvent in the separated liquid at the first or second time point is estimated using the calibration curve portion identified in the identification step S7. In this step, even if the physical property values ​​measured in the physical property measurement step S5 are measurements that belong to the region where concentration conversion is not possible in the nonlinear calibration curve (region Y shown in Figure 6), the concentration of the organic solvent in the separated liquid can be accurately estimated. In other words, it can be said that the concentration of the organic solvent is estimated based on the sign of ΔP.

[0067] The estimated concentration of the organic solvent obtained in the concentration estimation step S8 is input to the control unit 130. If the control unit 130 determines that the estimated concentration of the organic solvent has not reached a predetermined value, it continues to circulate the separated liquid stored in the liquid to be treated storage unit 22 as the liquid to be treated in the circulation path 25. Furthermore, the water is continuously or intermittently separated and removed to concentrate the organic solvent, while appropriately changing the separation conditions, until the estimated concentration of the organic solvent by the concentration estimation unit 158 ​​reaches a predetermined value. As a result, the liquid to be treated storage unit 22 stores separated liquid with an organic solvent concentration of the predetermined value. Separation conditions include the flow rate, pressure, and temperature of the separated liquid flowing through the circulation path 25, as well as the circulation time. These separation conditions can be changed by the control unit 130 controlling the degree of opening and closing of valves 25a and 25c, the pump 25b, and the temperature control unit 23 based on measurements taken by the flow rate sensor 25d, the pressure sensor 25e, and the temperature sensor 25f. As described above, the organic solvent recovery method of this embodiment allows for efficient concentration of the organic solvent because the separation process can be carried out while controlling the separation conditions based on the concentration of the organic solvent estimated in the concentration estimation step. The separated liquid, once the concentration of the organic solvent reaches a predetermined estimated value, is discharged from the separated liquid discharge pipe 26. The separated liquid discharged from the separated liquid discharge pipe 26 may be reused for substrate processing. In this case, the separated liquid discharge pipe 26 may be connected by pipeline to the organic solvent storage unit 133 so that the separated liquid can be supplied directly to the organic solvent storage unit 133. Alternatively, a filter or the like may be provided along the path of the separated liquid discharge pipe 26 to remove impurities such as particles.

[0068] (Other matters) In the above description, the most preferred embodiment of the present invention has been described. However, the present invention is not limited to this embodiment, and various modifications are possible within substantially the same scope as the technical idea described in the claims.

[0069] For example, in the above-described embodiment, the present invention was explained using the case where the temperature control unit is located in the middle of the circulation path. However, the present invention is not limited to this embodiment, and for example, the temperature control unit may be directly provided in the liquid to be treated storage unit. In this case, the temperature control unit is electrically connected to the control unit and adjusts the temperature of the liquid to be treated stored in the liquid to be treated storage unit in accordance with the operation command from the control unit. Even in such an embodiment, for example, if a zeolite membrane is used as the separation membrane in the separation unit, the separation performance can be improved.

[0070] Furthermore, in the above-described embodiment, the present invention was explained using the case where the separated liquid discharge pipe branches off from the circulation path as an example. However, the present invention is not limited to this embodiment, and for example, the pipe may be directly connected to the liquid to be treated storage section.

[0071] In the embodiments described above, an example was given in which the difference ΔP(P1-P2) was calculated based on the measured first physical property value P1 and second physical property value P2. However, the present invention is not limited to this embodiment, and for example, the difference ΔP(P2-P1) may be calculated. In this case, if ΔP is a positive value, it may be determined that the concentration of the organic solvent at the first physical property value P1 at the first time point or the second physical property value P2 at the second time point is lower than the concentration of the organic solvent at the maximum point Q where the physical property value is maximized. On the other hand, if ΔP is a negative value, it may be determined that the concentration of the organic solvent at the first physical property value P1 at the first time point or the second physical property value P2 at the second time point is higher than the concentration of the organic solvent at the maximum point Q where the physical property value is maximized. [Explanation of Symbols]

[0072] 1...Substrate processing unit, 2...Concentration and recovery unit (organic solvent recovery device), 11...Chamber, 12...Substrate holding section, 12a...Rotation drive section, 12b...Spin base, 12c...Chuck pin, 13...Supply section, 13a...Nozzle, 13b...Supply pipe, 13c...Organic solvent supply section, 13d...Water supply section, 14...Splash prevention cup, 21...Recovery pipe, 21a...Valve, 22...Processing liquid storage section, 23...Temperature control section, 24...Separation section, 25...Circulation path, 25a...Valve, 25b...Pump, 25c...Valve, 25d...Flow sensor, 25e...Pressure sensor, 25f...Temperature sensor, 25g...Physical property measurement section, 25h...Three-way valve, 26...Separated liquid discharge pipe, 27...Water discharge pipe, 27a...Valve, 100...Substrate processing device, 110...Substrate processing section, 111...Conveyor Section, 120... Indexer section, 121... Container holding section, 122... Conveying section, 122a... Base section, 122b... Multi-joint arm, 122c... Hand, 130... Control section, 131... Valve, 152... Organic solvent supply pipe, 133... Organic solvent storage section, 134... Pump, 135... Flow rate adjustment valve, 136... Valve, 137... Water supply pipe, 138... Water storage section, 139... Pump, 14 0...Flow rate adjustment valve, 141...Valve, 151...CPU, 152...ROM, 133...RAM, 154...Storage device, 155...Storage section, 156...Calculation section, 157...Specific section, 158... Concentration estimation section, S1... Recovery process, S2... Temperature adjustment process, S3... Separation process, S4... Calibration curve preparation process, S5... Physical property value measurement process, S6... Calculation process, S7... Specification process, S8... Concentration estimation process

Claims

1. A method for recovering an organic solvent, comprising separating the water from a liquid to be treated containing an organic solvent and water, and concentrating and recovering the organic solvent, A calibration curve preparation step involves preparing information for a nonlinear calibration curve that shows the relationship between the concentration of the organic solvent in the liquid to be treated and a predetermined physical property of the liquid to be treated, and that has one extreme point where the physical property is at its maximum or minimum. A physical property measurement step in which the physical properties of the liquid to be treated, from which the water has been continuously or continuously separated, are measured at minute intervals, The first physical property value P measured at the first time point in the aforementioned physical property value measurement process. １ The second physical property value P measured at the second time point, which is a small time interval after the first time point. ２ A calculation process to calculate the difference ΔP, From the sign of ΔP, the first physical property P １ or the second physical property value P ２ A process to identify the calibration curve portion to which it belongs, The process includes a concentration estimation step for estimating the concentration of the organic solvent at the first or second time point after the execution of the specified step, The calibration curve portion is either a portion of the calibration curve with a concentration lower than the concentration of the organic solvent at the extreme point, or a portion of the calibration curve with a concentration higher than the concentration of the organic solvent at the extreme point. Method for recovering organic solvents.

2. A method for recovering an organic solvent according to claim 1, The aforementioned extreme point is the point where the aforementioned physical property value reaches its maximum, The concentration estimation step is as follows: Said ΔP(P １ -P ２ If ) is a negative value, the concentration of the organic solvent at the first or second time point is estimated in the portion of the calibration curve where the concentration of the organic solvent is lower than the concentration of the organic solvent at the maximum point. Said ΔP(P １ -P ２ A method for recovering an organic solvent, wherein, if the value of ) is positive, the concentration of the organic solvent at the first or second time point is estimated in the portion of the calibration curve where the concentration is higher than the concentration of the organic solvent at the maximum point.

3. A method for recovering an organic solvent according to claim 1, The aforementioned extreme point is the point where the aforementioned physical property value reaches its maximum, The concentration estimation step is as follows: The aforementioned ΔP (P ２ - P １ ) is a positive value, in the calibration curve, the concentration of the organic solvent at the first time point or the second time point is estimated in a partial concentration region lower than the concentration of the organic solvent at the maximum point, Said ΔP(P ２ -P １ A method for recovering an organic solvent, wherein, if the value of ) is negative, the concentration of the organic solvent at the first or second time point is estimated in the portion of the calibration curve where the concentration is higher than the concentration of the organic solvent at the maximum point.

4. A method for recovering an organic solvent according to claim 1, The separation step includes circulating the liquid to be treated and separating the water through a membrane, either continuously or intermittently. The separation step is a method for recovering an organic solvent, in which the separation step is performed while controlling the separation conditions based on the concentration of the organic solvent estimated in the concentration estimation step, and the membrane separation is performed.

5. A method for recovering an organic solvent according to claim 4, A method for recovering an organic solvent, comprising a temperature adjustment step for adjusting the temperature of the liquid to be treated immediately before it is separated by membrane in the separation step.

6. An organic solvent recovery apparatus for separating water from a liquid to be treated containing an organic solvent and water, and concentrating and recovering the organic solvent, A storage unit that stores information on a nonlinear calibration curve that shows the relationship between the concentration of the organic solvent in the liquid to be treated and a predetermined physical property value of the liquid to be treated, and that has one extreme point where the physical property value is maximum or minimum, A physical property measurement unit measures the physical property values ​​of the liquid to be treated, from which the water has been continuously or continuously separated, at minute intervals. The first physical property value P measured at the first time point in the aforementioned physical property value measurement unit. １ The second physical property value P measured at the second time point, which is a small time interval after the first time point. ２ A calculation unit that calculates the difference ΔP from, From the sign of ΔP, the first physical property P １ or the second physical property value P ２ A specific section that identifies the calibration curve portion to which it belongs, The system includes a concentration estimation unit that estimates the concentration of the organic solvent at the first or second time point after the calibration curve portion has been identified by the identification unit, An organic solvent recovery device wherein the calibration curve portion is either a portion of the concentration region where the concentration of the organic solvent is lower than the concentration of the organic solvent at the extreme point of the calibration curve, or a portion of the concentration region where the concentration of the organic solvent is higher than the concentration of the organic solvent at the extreme point of the calibration curve.

7. The organic solvent recovery apparatus according to claim 6, The aforementioned extreme point is the point where the aforementioned physical property value reaches its maximum, The concentration estimation unit, Said ΔP(P １ -P ２ If ) is a negative value, the concentration of the organic solvent at the first or second time point is estimated in the portion of the calibration curve where the concentration of the organic solvent is lower than the concentration of the organic solvent at the maximum point. Said ΔP(P １ -P ２ An organic solvent recovery device that, when ) is a positive value, estimates the concentration of the organic solvent at the first or second time point in the portion of the calibration curve where the concentration is higher than the concentration of the organic solvent at the maximum point.

8. The organic solvent recovery apparatus according to claim 6, The aforementioned extreme point is the point where the aforementioned physical property value reaches its maximum, The concentration estimation unit, Said ΔP(P ２ -P １ If ) is a positive value, the concentration of the organic solvent at the first or second time point is estimated in the portion of the calibration curve where the concentration of the organic solvent is lower than the concentration of the organic solvent at the maximum point. Said ΔP(P ２ -P １ If the value is negative, an organic solvent recovery device that estimates the concentration of the organic solvent at the first or second time point in the portion of the calibration curve where the concentration is higher than the concentration of the organic solvent at the maximum point.

9. The organic solvent recovery apparatus according to claim 6, The separation unit circulates the liquid to be treated and performs membrane separation of the water continuously or intermittently, The separation unit is an organic solvent recovery device that performs membrane separation while controlling the separation conditions based on the concentration of the organic solvent estimated by the concentration estimation unit.

10. The organic solvent recovery apparatus according to claim 9, An organic solvent recovery apparatus comprising a temperature control unit for adjusting the temperature of the liquid to be processed immediately before it is separated by membrane in the separation unit.

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