Wastewater treatment equipment

Abstract

It suppresses the growth of microorganisms in wastewater and also decomposes existing microorganisms. [Solution] A waste liquid treatment apparatus comprising: a storage tank for receiving waste liquid; a filter unit having an inlet for receiving the waste liquid; a filter for filtering the waste liquid flowing in from the inlet; and an outlet for discharging the waste liquid filtered by the filter; a waste liquid supply path for supplying the waste liquid from the storage tank to the inlet of the filter unit; a waste liquid discharge path for discharging the waste liquid from the outlet of the filter unit; an ultrasonic oscillator; an ultrasonic transducer connected to the ultrasonic oscillator; and a horn provided in the storage tank and connected to the ultrasonic transducer for transmitting the ultrasonic vibrations generated by the ultrasonic transducer.

Description

Technical Field

[0001] The present invention relates to a waste liquid treatment device for purifying waste liquid discharged from a processing device or the like for processing a wafer formed of a semiconductor material.

Background Art

[0002] In the manufacturing process of device chips mounted on electronic devices, first, a plurality of planned division lines (streets) intersecting each other are set on the surface of a wafer formed of a semiconductor material. Then, devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integrations) are formed in each region partitioned by the planned division lines. After that, when the wafer is divided along the planned division lines, a plurality of device chips can be obtained. For dividing the wafer, a cutting device or the like that cuts the wafer with an annular cutting blade is used.

[0003] In recent years, with the miniaturization and thinning of electronic devices, thinning of device chips has also been required. Therefore, before dividing the wafer, the back surface side of the wafer may be polished to thin the wafer. For the polishing process of the wafer, a polishing device or the like that polishes the wafer with a polishing wheel provided with a plurality of polishing abrasives is used.

[0004] When processing a wafer using processing devices such as the above cutting device and polishing device, a processing liquid is supplied to the wafer. By this processing liquid, the wafer and the processing tool (cutting blade, polishing wheel, etc.) are cooled, and the chips (processing chips) generated during processing are washed away. However, if the processing liquid contains impurities, problems such as the impurities adhering to the wafer and leaving marks, or the impurities causing malfunction of the device may occur, and the quality of the device chip may deteriorate. Therefore, pure water containing no impurities is used as the processing liquid.

[0005] The pure water used in processing equipment is discharged outside the equipment as wastewater and disposed of. However, the amount of pure water used in processing equipment is large, resulting in significant disposal costs. Therefore, methods have been proposed to purify the wastewater discharged from processing equipment and reuse the water. For example, wastewater treatment equipment that filters wastewater to produce clean water or pure water is known (see Patent Documents 1, 2, and 3).

[0006] The wastewater treatment system includes a storage tank that receives and stores wastewater discharged from the processing equipment. The wastewater stored in the storage tank is then filtered to remove processing debris and other contaminants. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2009-214193 [Patent Document 2] Japanese Patent Publication No. 2010-82791 [Patent Document 3] Japanese Patent Publication No. 2009-190128 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In wastewater treatment equipment storage tanks, microorganisms such as bacteria proliferate in the stored wastewater. Processing equipment uses processing fluid maintained at approximately 23°C to process multiple workpieces with uniform quality. Therefore, the temperature of the wastewater discharged from the processing equipment remains stable at a temperature higher than room temperature. This temperature particularly promotes the growth of microorganisms in the wastewater.

[0009] When microorganisms proliferate in wastewater stored in storage tanks, they can form clumps of a certain size or adhere to the inner walls of the tanks, making them difficult to discharge. Therefore, frequent maintenance, such as cleaning or replacing the storage tanks, was necessary.

[0010] Furthermore, the proliferation of microorganisms in the wastewater leads to its contamination. While wastewater treatment systems purify the wastewater supplied from the storage tank, if the wastewater contamination is severe, the purification intensity needs to be increased, placing a heavy burden on the various purification units. In other words, the proliferation of microorganisms sometimes necessitates frequent maintenance of the various purification units. Therefore, it is desirable to decompose microorganisms in the wastewater within the storage tank to suppress their proliferation.

[0011] This invention has been made in view of the above problems, and its objective is to provide a wastewater treatment device that can suppress the growth of microorganisms in a storage tank into which wastewater is supplied and stored, and can also decompose microorganisms. [Means for solving the problem]

[0012] According to one aspect of the present invention, a waste liquid treatment device is provided, comprising: a storage tank for receiving waste liquid; a filter unit having an inlet for receiving the waste liquid; a filter for filtering the waste liquid flowing in from the inlet; and an outlet for discharging the waste liquid filtered by the filter; a waste liquid supply path for supplying the waste liquid from the storage tank to the inlet of the filter unit; a waste liquid discharge path for discharging the waste liquid from the outlet of the filter unit; an ultrasonic oscillator; an ultrasonic transducer connected to the ultrasonic oscillator; and a horn provided in the storage tank and connected to the ultrasonic transducer for transmitting ultrasonic vibrations generated by the ultrasonic transducer.

[0013] Preferably, the system further includes a contamination detector for detecting the degree of contamination of the waste liquid and a controller, the controller controlling the ultrasonic oscillator by referring to the degree of contamination of the waste liquid detected by the contamination detector to adjust the characteristics of the ultrasonic vibrations generated by the ultrasonic transducer. [Effects of the Invention]

[0014] A waste liquid treatment apparatus according to an aspect of the present invention includes an ultrasonic oscillator, an ultrasonic vibrator connected to the ultrasonic oscillator, and a horn provided in a storage tank, connected to the ultrasonic vibrator, and transmitting ultrasonic vibrations generated by the ultrasonic vibrator. Therefore, ultrasonic vibrations can be applied to the waste liquid stored in the storage tank. When ultrasonic vibrations are applied to the waste liquid, microorganisms in the waste liquid can be destroyed and their growth can be suppressed.

[0015] When microorganisms in the waste liquid can be destroyed, it becomes easier for the microorganisms to be discharged from the storage tank, and the progress of contamination of the waste liquid in the storage tank is suppressed. Therefore, not only can the maintenance frequency of the storage tank be reduced, but also the load on various purification units of the waste liquid treatment apparatus can be reduced and their maintenance frequencies can be reduced.

[0016] Therefore, according to the present invention, there is provided a waste liquid treatment apparatus that can suppress the growth of microorganisms and decompose microorganisms in a waste liquid storage tank where waste liquid is supplied and stored.

Brief Description of the Drawings

[0017] [Figure 1] It is a perspective view schematically showing a processing apparatus and a waste liquid treatment apparatus. [Figure 2] It is a perspective view schematically showing the internal configuration of the waste liquid treatment apparatus. [Figure 3] It is a cross-sectional view schematically showing a waste liquid storage tank (storage tank) according to an example. [Figure 4] It is a cross-sectional view schematically showing a waste liquid storage tank (storage tank) according to another example.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments according to an aspect of the present invention will be described with reference to the accompanying drawings. First, a configuration example of the waste liquid treatment apparatus according to the present embodiment will be described. FIG. 1 is a perspective view schematically showing a waste liquid treatment apparatus 22 and a processing apparatus 2 to which the waste liquid treatment apparatus 22 is connected and used.

[0019] In a processing apparatus, for example, a workpiece such as a wafer formed of a semiconductor material such as Si (silicon) or SiC (silicon carbide) is processed. A plurality of devices such as ICs and LSIs are formed on the surface of the wafer. When the wafer is divided for each device, individual device chips are formed. Further, if the back side of the wafer is ground in advance before dividing the wafer to thin the wafer, finally, a thin device chip can be obtained. The processing apparatus performs processing such as grinding and dividing on the workpiece.

[0020] FIG. 1 is a perspective view schematically showing, as an example of the processing apparatus 2, a cutting apparatus including an annular cutting blade mounted on a spindle. However, the processing apparatus 2 connected and used with the waste liquid treatment apparatus 22 according to the present embodiment is not limited to a cutting apparatus. For example, a grinding wheel mounted with grinding wheels arranged in an annular shape may be mounted on a spindle and rotated, and a grinding apparatus that performs grinding by bringing the grinding wheel moving on an annular orbit into contact with a workpiece may be used. Hereinafter, the case where the processing apparatus 2 is a cutting apparatus will be continued to be described as an example.

[0021] As shown in FIG. 1, a cassette table 6 on which a cassette 8 is placed is provided at a corner of a base 4 of the processing apparatus 2. The cassette table 6 can be moved up and down in the vertical direction by a lifting mechanism (not shown). In FIG. 2, the outline of the cassette 8 placed on the cassette table 6 is shown by a two-dot chain line.

[0022] An unloading unit 10 for unloading the workpiece accommodated in the cassette 8 placed on the cassette table 6 is provided at a position adjacent to the cassette table 6 on the upper surface of the base 4. The unloading unit 10 has a gripping portion capable of gripping the workpiece on the front surface. When unloading the workpiece accommodated in the cassette 8, the gripping portion is inserted into the cassette 8 to grip the workpiece with the gripping portion, and then the gripping portion is moved in a direction away from the cassette 8.

[0023] A chuck table 14 capable of suction-holding a workpiece is provided on the upper surface of the base 4, adjacent to the cassette table 6. The chuck table 14 is movable in both directions, away from and towards the cassette table 6. In addition, a first transport unit 12 is provided on the upper surface of the base 4, adjacent to the discharge unit 10 and the chuck table 14.

[0024] The first transport unit 12 has a vertically movable and rotatable shaft portion that protrudes upward from the upper surface of the base 4, an arm portion that extends horizontally from the upper end of the shaft portion, and a holding portion provided below the tip of the arm portion. The workpiece pulled out from the cassette 8 is transported to the chuck table 14 by the first transport unit 12.

[0025] At the destination of the chuck table 14, there is a processing unit (cutting unit) 16 for processing (cutting) the workpiece held by the chuck table 14. The processing unit 16 comprises a cutting blade having an annular grinding wheel portion on its outer circumference, and a spindle with the cutting blade attached to its tip, which is aligned with the Y-axis direction and serves as the rotation axis of the cutting blade.

[0026] A rotational drive source (not shown), such as a motor, is connected to the base end of this spindle. When the rotating cutting blade is driven into the workpiece held by the chuck table 14, the workpiece can be cut. Afterwards, the chuck table 14 is returned to a position adjacent to the cassette table 6.

[0027] A cleaning unit 18 for cleaning the workpiece after processing is provided on the upper surface of the base 4, adjacent to the chuck table 14 and the first transport unit 12. The cleaning unit 18 is equipped with a spinner table for holding the workpiece. A rotational drive source (not shown) for rotating the spinner table at a predetermined speed is connected to the lower part of the spinner table. The processing apparatus 2 is equipped with a second transport unit 20 for transporting the workpiece from the chuck table 14 to the cleaning unit 18.

[0028] When cleaning a workpiece in the cleaning unit 18, a cleaning fluid (typically a mixed fluid of pure water and air) is sprayed onto the workpiece while the spinner table is rotated. When storing the workpiece cleaned in the cleaning unit 18 into the cassette 8, the first transport unit 12 is used to transport the workpiece from the cleaning unit 18 to the discharge unit 10. The discharge unit 10 is then moved toward the cassette 8 to push the workpiece into the cassette 8.

[0029] When a workpiece is cut with a cutting blade, frictional heat is generated, causing the temperature of both the cutting blade and the workpiece to rise. Additionally, machining chips are generated from the workpiece. Therefore, supplying machining fluid to the cutting blade and the workpiece while cutting allows for the rapid removal of machining chips and the cooling of both the cutting blade and the workpiece.

[0030] Furthermore, even if the processing device 2 is a grinding device that grinds a workpiece with a grinding wheel mounted on a grinding wheel, frictional heat and processing chips are generated when grinding the workpiece. By supplying processing fluid to the grinding wheel and the workpiece while grinding, processing chips can be quickly removed and the grinding wheel and the workpiece can be cooled.

[0031] However, if the processing fluid or cleaning fluid contains impurities, problems may arise such as the impurities adhering to the workpiece and leaving residue, or the impurities causing malfunctions in the devices formed on the workpiece, potentially degrading the quality of the device chip. Therefore, pure water or similar fluids free of impurities are used for the processing fluid and cleaning fluid.

[0032] The pure water used in processing apparatus 2 is discharged outside of processing apparatus 2 as wastewater and disposed of. However, the amount of pure water used in processing apparatus 2 is large, resulting in significant disposal costs. Therefore, a wastewater treatment device 22 is used to treat the wastewater discharged from processing apparatus 2 and regenerate pure water. The wastewater treatment device 22 generates pure water by, for example, filtering the wastewater to produce clean water, irradiating the clean water with ultraviolet light to destroy organic matter, and removing impurity ions from the clean water using ion exchange resin. The generated pure water is then supplied to processing apparatus 2.

[0033] Next, an example of the configuration of the waste liquid treatment device 22 according to this embodiment will be described. The waste liquid treatment device 22 is connected to a processing device 2 that uses pure water. The waste liquid treatment device 22 has a rectangular parallelepiped housing 24 that houses each component that constitutes the waste liquid treatment device 22. The upper front of the housing 24 is provided with a display unit 32, which is composed of a liquid crystal display or the like, that displays the status of the waste liquid treatment device 22, and an input unit 30, which is composed of a touch panel or buttons, which serves as an interface for an operator to input commands to the waste liquid treatment device 22.

[0034] The wastewater treatment device 22 is connected to the processing device 2 via a drainage channel 26 and a water supply channel 28, which are composed of pipes, tubes, etc. The pure water produced by the wastewater treatment device 22 is sent to the processing device 2 through the water supply channel 28, and the water (wastewater) generated in the processing device 2 is sent to the wastewater treatment device 22 via the drainage channel 26.

[0035] Figure 2 is a schematic perspective view showing the internal components of the housing 24 of the waste liquid treatment device 22. In Figure 2, the water channels through which water flows are partially omitted for ease of explanation. The waste liquid treatment device 22 includes a frame 34 that supports each component.

[0036] A waste liquid storage tank (storage tank) 36 is provided on the bottom surface of the frame 34 to store water (waste liquid) discharged from the processing device 2. The water discharged from the processing device 2 is supplied to the waste liquid storage tank 36 via the drainage channel 26 and stored there. Specifically, water containing foreign matter such as processing scraps and impurity ions is supplied from the processing device 2 to the waste liquid storage tank 36 as processing waste liquid.

[0037] A waste liquid supply pump 38 is connected to the waste liquid storage tank 36 to pump out the water stored in the waste liquid storage tank 36. The waste liquid supply pump 38 is a pump that supplies the water stored in the waste liquid storage tank 36 to the first filtration unit 44, which will be described later. The amount of water supplied from the waste liquid storage tank 36 to the first filtration unit 44 is controlled by this waste liquid supply pump 38.

[0038] A pair of guide rails 40 are provided above the waste liquid storage tank 36. The pair of guide rails 40 are fixed to the frame 34 along the length of the waste liquid treatment device 22, at a predetermined distance apart in the width direction of the waste liquid treatment device 22. A rectangular receiving pan 42 is mounted on the pair of guide rails 40 in a manner that allows it to slide along the guide rails 40. This allows the receiving pan 42 to be pulled out of the frame 34 and to be retracted into the frame 34.

[0039] A first filter unit 44 is detachably mounted on the receiving tray 42 to filter water (waste liquid) supplied from the waste liquid storage tank 36. The inlet (inlet section) 46 at the upper end of the first filter unit 44 is connected to a waste liquid supply pump 38 by a waste liquid supply passage (hose) (not shown). The water stored in the waste liquid storage tank 36 is supplied to each first filter unit 44 through the waste liquid supply passage by the waste liquid supply pump 38. Although Figure 2 and other figures show an example in which two first filter units 44 are provided on the receiving tray 42, there is no limit to the number of first filter units 44.

[0040] The first filtration unit 44 includes a filter (not shown) made of, for example, activated carbon, zeolite, cloth, resin fiber, glass fiber, metal mesh, reverse osmosis membrane (RO membrane), etc. The first filtration unit 44 purifies the water by removing impurities such as processing waste contained in the water flowing in from the inlet (inflow section) 46 by adsorption or filtration. The water (clean water) filtered by the first filtration unit 44 accumulates in the receiving tray 42 and is discharged from the outlet (drainage channel) 48.

[0041] In the area adjacent to the waste liquid storage tank 36 below the first filtration unit 44 and the receiving tray 42, a fresh water storage tank (filtered water storage tank) 54 is provided for storing the water (fresh water) filtered by the first filtration unit 44. The fresh water storage tank 54 is provided on the upper side of the fresh water storage tank 54 and includes an inlet 56 into which water flows.

[0042] Each of the first filtration units 44 is connected to a fresh water storage tank 54 via a receiving tray 42. Specifically, the outlet (drainage channel) 48 of the receiving tray 42 and the inlet 56 of the fresh water storage tank 54 are connected by a waste liquid discharge channel 50 formed by a flexible hose. The waste liquid discharge channel 50 is supported, for example, by an inclined support plate 52. The water (fresh water) filtered and discharged in the first filtration unit 44 is temporarily stored in the receiving tray 42, and then supplied to and stored in the fresh water storage tank (storage tank) 54 via the waste liquid discharge channel 50.

[0043] In other words, the wastewater treatment device 22 according to this embodiment includes a filter unit 43 which comprises an inlet 46 for receiving wastewater, a filter for filtering the wastewater flowing in from the inlet 46, and an outlet (drainage channel) 48 for discharging the filtered wastewater (clean water). The wastewater treatment device 22 also includes a wastewater supply channel (hose) for supplying wastewater from the wastewater storage tank 36 to the inlet 46 of the filter unit 43, and a wastewater discharge channel (hose) 50 for discharging wastewater (clean water) from the (drainage channel) 48 of the filter unit 43.

[0044] A pair of guide rails 70 are provided adjacent to the fresh water storage tank 54 of the waste liquid treatment device 22. The guide rails 70 are fixed to the frame 34 in the same manner as the guide rails 40, except that their mounting positions are different. A rectangular receiving pan 72 is mounted on the pair of guide rails 70 in a manner that allows it to slide along the guide rails 70. This allows the receiving pan 72 to be pulled out of the frame 34 and to be moved back into the frame 34.

[0045] The fresh water storage tank (storage tank) 54 is equipped with an outlet (not shown) at its lower part. A fresh water supply pump (not shown) is connected to the downstream side of the fresh water storage tank 54 via a water channel. A UV irradiation unit 62, which includes an ultraviolet light source such as an ultraviolet lamp and irradiates the waste liquid (fresh water) supplied from the fresh water storage tank 54 with ultraviolet light, is connected to the downstream side of the fresh water supply pump via a water channel. The UV irradiation unit 62 is mounted on a receiving tray 72.

[0046] In the ultraviolet irradiation unit 62, ultraviolet light is irradiated onto the wastewater (clean water) for sterilization. Irradiating the wastewater with ultraviolet light also destroys other organic substances contained in the wastewater. An ion exchange resin unit 64 is connected downstream of the ultraviolet irradiation unit 62.

[0047] Figure 2 schematically shows a case in which two ion exchange resin sections 64 are detachably provided on a receiving tray 72, but the number of ion exchange resin sections 64 is not limited to this. Each ion exchange resin section 64 contains ion exchange resin and exchanges ions contained in water irradiated with ultraviolet light by the ultraviolet irradiation unit 62.

[0048] The ion exchange resin section 64 includes, for example, a cylindrical container and ion exchange resin filled in the container. A channel is formed inside the container through which water flows between the ion exchange resins, and water entering the ion exchange resin section 64 passes through the ion exchange resins within the container.

[0049] For example, the container contains an ion exchange resin that exchanges cations (cation exchange resin) and an ion exchange resin that exchanges anions (anion exchange resin) in a mixed state. Then, ions other than hydrogen ions and hydroxide ions in the water supplied to the ion exchange resin section 64 are exchanged for hydrogen ions or hydroxide ions. In other words, pure water is produced by the ion exchange resin section 64.

[0050] The waste liquid (pure water) from which ions have been exchanged by the ion exchange resin is sent to the second filtration section 68. The second filtration section 68 is detachably mounted on the receiving tray 72 and has the function of finally filtering the waste liquid (pure water) from which ions have been exchanged by the ion exchange resin section 64.

[0051] The second filtration section 68, like the first filtration section 44, includes a filter (not shown) made of, for example, activated carbon, zeolite, cloth, resin fiber, glass fiber, metal mesh, reverse osmosis membrane (RO membrane), etc.

[0052] The water discharged as waste liquid from the processing apparatus 2 undergoes the final stage of purification when it reaches the second filtration section 68. Since the turbidity (impurities) contained in the water are extremely small and present in minute quantities, the filter is required to have performance suitable for removing such turbidity. For example, the filter in the second filtration section 68 should have a finer mesh than the filter in the first filtration section 44, and a membrane of a level known as a precision filter should be used.

[0053] The second filtration unit 68 further purifies the water by adsorbing or filtering out trace amounts of turbidity contained in the incoming wastewater (pure water) using a filter. The pure water produced by filtering the wastewater in the second filtration unit 68 proceeds downstream and is sent to the pure water supply unit 74 fixed to the upper part of the frame 34.

[0054] The pure water supply unit 74 has the function of supplying the pure water produced by filtration in the second filtration unit 68 to the processing apparatus 2 via the water supply channel 28. The pure water supply unit 74 includes a pure water storage tank (not shown) for storing the produced pure water, and a temperature controller (not shown) for adjusting the temperature of the pure water supplied from the pure water storage tank to the processing apparatus 2. For example, the temperature controller is equipped with a temperature control mechanism (not shown) such as a heat source like an electric heating wire or a cooling source like a Peltier element, and has the function of adjusting the temperature of the pure water supplied to the processing apparatus 2.

[0055] The water supplied from the pure water supply unit 74 to the processing apparatus 2 has foreign matter and ions removed and is used as pure water in the processing apparatus 2. In this way, the waste liquid discharged from the processing apparatus 2 is purified by the waste liquid treatment device 22 and returned to the processing apparatus 2 for use as pure water.

[0056] A controller (control unit) 76 connected to each component of the waste liquid treatment device 22 is provided at the top of the frame 34. The components of the waste liquid treatment device 22, such as the pump, are controlled by the controller 76.

[0057] The controller 76 is composed of a computer that includes, for example, a processor represented by a CPU (Central Processing Unit) and memory. The memory includes main memory such as DRAM (Dynamic Random Access Memory) and auxiliary storage such as flash memory, HDD (Hard Disk Drive), and SSD (Solid State Drive).

[0058] The auxiliary storage device stores software, including a predetermined program. The controller 76's functions are realized by operating the processor and other components according to this program. Further details regarding the controller 76's configuration and functions will be described later.

[0059] The controller 76 is connected to an input unit 30 for inputting predetermined information to the waste liquid treatment device 22, and a display unit 32 for displaying predetermined information related to the waste liquid treatment device 22. For example, the input unit 30 is composed of multiple operation keys, and the display unit 32 is composed of a display. For example, conditions for water production (amount of pure water produced, temperature, etc.) are input to the controller 76 via the input unit 30. The display unit 32 also displays the operating status of the waste liquid treatment device 22 and the conditions for water production.

[0060] In the wastewater storage tank (storage tank) 36 of the wastewater treatment device 22 described above, microorganisms such as bacteria proliferate in the stored wastewater. In the processing device 2, processing fluid kept at a temperature of about 23°C is used in order to process multiple workpieces with uniform quality. Therefore, the temperature of the wastewater discharged from the processing device 2 is stable at a temperature higher than room temperature. And in wastewater at this temperature, the proliferation of microorganisms is particularly promoted.

[0061] When microorganisms proliferate in the waste liquid stored in the waste liquid storage tank (storage tank) 36, the microorganisms may form clumps of a certain size or larger, or adhere to the inner wall of the waste liquid storage tank 36, making it difficult to discharge the waste liquid from the tank. Therefore, it was necessary to perform maintenance such as cleaning or replacing the waste liquid storage tank 36 at a high frequency.

[0062] Furthermore, the proliferation of microorganisms in the wastewater leads to increased contamination. In the wastewater treatment device 22, the wastewater supplied from the wastewater storage tank 36 is purified, but if the wastewater contamination is severe, the purification intensity needs to be increased, placing a heavy burden on the various purification units (first filtration unit 44, ultraviolet irradiation unit 62, second filtration unit 68, etc.). In other words, due to the proliferation of microorganisms, maintenance of the various purification units sometimes had to be performed at a high frequency.

[0063] Therefore, it is desirable to suppress the growth of microorganisms or decompose them in the waste liquid storage tank (storage tank) 36. Accordingly, in the waste liquid treatment device 22 according to this embodiment, microorganisms are destroyed in the waste liquid storage tank (storage tank) 36 by ultrasonic vibration.

[0064] Figure 3 is a schematic cross-sectional view of the waste liquid storage tank (storage tank) 36. The waste liquid storage tank 36 comprises a main body 80 having an internal space 82 for storing waste liquid. An inlet 86 is formed at the top of the main body 80. The waste liquid 84 supplied from the processing device 2 to the waste liquid treatment device 22 flows into the internal space 82 through the inlet 86 and is stored inside the internal space 82.

[0065] The waste liquid 84 stored in the internal space 82 of the waste liquid storage tank 36 is sucked up by the waste liquid supply pump 38 and sent to the filter unit 43 (first filtration section 44). The waste liquid supply pump 38 is connected to a suction passage 88 that leads to the internal space 82 of the waste liquid storage tank 36. The waste liquid 84 stored in the internal space 82 is sucked up by the waste liquid supply pump 38 through the suction passage 88 and discharged.

[0066] The waste liquid treatment device 22 according to this embodiment includes an ultrasonic transducer 92 provided inside the waste liquid storage tank 36 and capable of generating ultrasonic vibrations, and an ultrasonic oscillator 90 connected to the ultrasonic transducer 92 and supplying high-frequency power to the ultrasonic transducer 92. Furthermore, it includes a horn 94 provided inside the waste liquid storage tank 36 and connected to the ultrasonic transducer 92 to transmit the ultrasonic vibrations generated by the ultrasonic transducer 92.

[0067] The ultrasonic transducer 92 preferably uses lead zirconate titanate (PZT), which generates ultrasonic vibrations by expanding and contracting in response to high-frequency power from the ultrasonic oscillator 90. The horn 94 is made of a metal material such as iron, titanium, or aluminum. The horn 94 is shaped to be suitable for amplifying ultrasonic vibrations.

[0068] Furthermore, in the example shown in Figure 3, the ultrasonic oscillator 90 is fixed in the internal space 82 of the waste liquid storage tank 36 at a height that does not submerge it in the waste liquid 84 stored in the waste liquid storage tank 36. The horn 94 connected to the ultrasonic transducer 92 extends to a height that contacts the waste liquid 84 stored in the waste liquid storage tank 36.

[0069] Furthermore, in the example shown in Figure 3, the ultrasonic oscillator 90 is located outside the waste liquid storage tank 36 and is connected by wires or the like to the ultrasonic transducer 92 located inside the waste liquid storage tank 36. The ultrasonic oscillator 90 is also connected to a controller 76 (see Figure 2), and the controller 76 controls the characteristics of the ultrasonic vibrations generated by the ultrasonic transducer 92 by controlling the characteristics of the high-frequency power that the ultrasonic oscillator 90 supplies to the ultrasonic transducer 92.

[0070] When the controller 76 activates the ultrasonic oscillator 90 and supplies high-frequency power to the ultrasonic transducer 92, ultrasonic vibrations are generated in the ultrasonic transducer 92, and these ultrasonic vibrations are amplified by the horn 94 and applied to the waste liquid 84 stored in the waste liquid storage tank 36.

[0071] When ultrasonic vibrations are applied to the waste liquid 84, microorganisms present in the waste liquid 84 and on the walls of the internal space 82 are destroyed and decomposed by the ultrasonic vibrations. As a result, the proliferation of microorganisms is suppressed. Furthermore, when ultrasonic vibrations are applied to the waste liquid 84, organic substances other than microorganisms in the waste liquid 84 are also destroyed and broken down into smaller pieces.

[0072] Furthermore, when organic matter such as microorganisms is destroyed and broken down into smaller pieces in the waste liquid 84 stored in the internal space 82 of the waste liquid storage tank (storage tank) 36, the organic matter separates from the walls of the internal space 82 and becomes more likely to float in the waste liquid 84. As a result, the organic matter, along with the waste liquid 84 stored in the internal space 82, is more easily sucked up by the waste liquid supply pump 38, and organic matter is less likely to accumulate in the waste liquid storage tank 36. Consequently, the frequency of maintenance and replacement of the waste liquid storage tank 36 is reduced.

[0073] In the wastewater storage tank 36, organic matter such as microorganisms that have been broken down into smaller pieces is filtered out and recovered by the filter of the filter unit 43 (first filtration section 44) described above. In other words, the wastewater 84 is purified in the filter unit 43, and clean water is produced.

[0074] In the waste liquid treatment device 22 according to this embodiment, contamination of the waste liquid 84 stored in the waste liquid storage tank 36 is less likely to progress, thus reducing the load on the filter unit 43 (first filtration section 44). Therefore, the frequency of maintenance such as cleaning and replacement of the filter unit 43 (first filtration section 44) can be reduced. Furthermore, the load on subsequent purification units (ultraviolet irradiation unit 62, second filtration section 68, etc.) can also be reduced, thus reducing the frequency of maintenance for these as well.

[0075] Furthermore, the ultrasonic oscillator 90 does not need to be running continuously while the waste liquid treatment device 22 is operating, nor does it need to operate at a constant output. In other words, the ultrasonic oscillator 90 should supply high-frequency power to the ultrasonic transducer 92 at the necessary timing, thereby generating ultrasonic vibrations in the ultrasonic transducer 92 at the required intensity.

[0076] Here, the required intensity of the ultrasonic vibration is determined by the amount of organic matter, such as microorganisms, contained in the waste liquid 84 stored in the waste liquid storage tank (storage tank) 36. That is, if the amount of organic matter in the waste liquid 84 is large, it is necessary to apply high-intensity ultrasonic vibration to the waste liquid 84. Conversely, if the amount of organic matter in the waste liquid 84 is small, it is possible to apply low-intensity ultrasonic vibration to the waste liquid 84 in order to reduce the power consumption of the ultrasonic oscillator 90. The controller 76 should determine the characteristics of the ultrasonic vibration based on the amount of organic matter contained in the waste liquid 84.

[0077] For example, the waste liquid treatment apparatus 22 according to this embodiment preferably includes a contamination detector (not shown) for detecting the degree of contamination of the waste liquid 84. In this case, the controller 76 controls the ultrasonic oscillator 90 by referring to the degree of contamination of the waste liquid 84 detected by the contamination detector and adjusts the characteristics of the ultrasonic vibrations generated by the ultrasonic transducer 92. The controller 76 determines the ultrasonic frequency, amplitude, and duration of application of ultrasonic vibrations as characteristics of the ultrasonic vibrations applied to the waste liquid.

[0078] Furthermore, a spectrophotometer, such as a UV-Vis-NIR spectrophotometer, can be used as the contamination detector. When using a spectrophotometer as the contamination detector, waste liquid 84 is passed through a cell of a predetermined width while light with predetermined characteristics is transmitted through the cell in the width direction. The transmitted light that has passed through the cell is received by a sensor, and the intensity of the transmitted light is measured for each wavelength. This allows the absorbance of the waste liquid 84 for each wavelength to be obtained. For the sensor that receives the transmitted light, a photomultiplier tube (photomultiplier), silicon photodiode, InGaAs photodiode, etc., can be used.

[0079] The type of organic substance contained in the waste liquid 84 is one of the factors that determine the absorbance of the waste liquid 84 at each wavelength. In other words, insights into the type of organic substance contained in the waste liquid 84 can be obtained from the wavelength of light at which a maximum value is observed in the absorbance distribution of light transmitted through the waste liquid 84. As the destruction of organic substances in the waste liquid 84 progresses by the ultrasonic oscillator 90, the content of each organic substance in the waste liquid 84 changes, and therefore the maximum absorption wavelength in the absorbance distribution of transmitted light at each wavelength changes.

[0080] Furthermore, the amount of organic matter contained in the waste liquid 84 is one of the factors that determine the magnitude of the absorbance of the waste liquid 84. In other words, insights into the amount of organic matter contained in the waste liquid 84 can be obtained from the magnitude of the absorbance of the light transmitted through the waste liquid 84. Then, as the destruction of organic matter in the waste liquid 84 progresses by the ultrasonic oscillator 90, the content of organic matter in the waste liquid 84 changes, and therefore the absorbance of the waste liquid 84 changes.

[0081] Therefore, by using a spectrophotometer as a contamination detector, information regarding the type and amount of organic matter can be obtained as information about the degree of contamination in the waste liquid 84. The controller 76 controls the ultrasonic oscillator 90 by referring to this information about the degree of contamination so that the organic matter contained in the waste liquid 84 can be destroyed as necessary and sufficiently, and adjusts the characteristics of the ultrasonic vibrations generated by the ultrasonic transducer 92. In addition to a spectrophotometer, commercially available turbidimeters and the like can be used as contamination detectors.

[0082] As described above, the waste liquid treatment device 22 according to this embodiment can apply ultrasonic vibrations to the waste liquid 84 stored in the waste liquid storage tank 36. Applying ultrasonic vibrations to the waste liquid 84 can suppress the growth of microorganisms in the waste liquid 84 and destroy microorganisms.

[0083] It should be noted that the present invention is not limited to the embodiments described above and can be implemented with various modifications. For example, in the waste liquid treatment apparatus 22 according to the above embodiment, the case in which ultrasonic vibrations are applied to the waste liquid 84 discharged from the processing apparatus and stored in the waste liquid storage tank 36 to destroy microorganisms etc. was described. However, one aspect of the present invention is not limited thereto.

[0084] In other words, in the wastewater treatment apparatus 22 according to one aspect of the present invention, ultrasonic vibrations may be applied to the wastewater at a location different from the wastewater storage tank 36. For example, ultrasonic vibrations may be applied to the wastewater (clean water) stored in the clean water storage tank (storage tank) 54, so that microorganisms and other organic substances contained in the wastewater are destroyed by the ultrasonic vibrations. In this case, the fragmented organic substances such as microorganisms proceed downstream along the flow path with the wastewater (clean water) and are filtered out by the second filtration unit 68. In other words, in this case, the second filtration unit 68 and the like function as a filter unit.

[0085] Furthermore, although the above embodiment described a case in which the ultrasonic transducer 92 is not submerged in the waste liquid 84 within the internal space 82 of the waste liquid storage tank 36, one aspect of the present invention is not limited to this. That is, the ultrasonic transducer that generates ultrasonic vibrations to be applied to the waste liquid 84 may be submerged in the waste liquid 84. In other words, the waste liquid treatment apparatus 22 according to one aspect of the present invention may include an ultrasonic transducer that is submerged in the waste liquid 84.

[0086] Figure 4 is a schematic cross-sectional view of a waste liquid storage tank 36 in which an ultrasonic transducer 92 that does not sink in the waste liquid 84 and an ultrasonic transducer 96 that is submerged in the waste liquid 84 are provided in the internal space 82. The ultrasonic transducer 92 that does not sink in the waste liquid 84 is as described in Figure 3. The ultrasonic transducer 96 is a submersible ultrasonic transducer that is thrown into the waste liquid 84, and like the ultrasonic transducer 92, it is connected to an ultrasonic oscillator 90 and can generate ultrasonic vibrations by receiving high-frequency power from the ultrasonic oscillator 90.

[0087] The ultrasonic transducer 96, which is submerged in the waste liquid 84, is preferably equipped with a waterproof function to prevent damage from the waste liquid 84. For example, the ultrasonic transducer 96 and the horn may be housed in a cylindrical container made of metal such as stainless steel or plastic to protect the ultrasonic transducer 96 from the waste liquid 84. When the waste liquid treatment device 22 is equipped with an ultrasonic transducer 96 that is submerged in the waste liquid 84, ultrasonic vibrations can be applied to the waste liquid 84 regardless of the amount of waste liquid 84 stored in the waste liquid storage tank 36.

[0088] Furthermore, the waste liquid treatment device 22 according to one aspect of the present invention may be equipped with two ultrasonic transducers 92 and 96, or with only one of them. That is, the waste liquid treatment device 22 may be equipped with only an ultrasonic transducer 96 that is submerged in the waste liquid 84. Also, when the waste liquid treatment device 22 is equipped with two ultrasonic transducers 92 and 96, it is not necessary for both ultrasonic transducers 92 and 96 to operate simultaneously; one may be operating while the other remains dormant.

[0089] When the two ultrasonic transducers 92 and 96 are operated individually, ultrasonic vibrations can be applied to the waste liquid 84 stored in the waste liquid storage tank 36 in a way that precisely corresponds to the amount and degree of contamination of the waste liquid 84.

[0090] Furthermore, the structures, methods, etc., according to the above embodiments can be modified as appropriate without departing from the scope of the objectives of the present invention. [Explanation of symbols]

[0091] 2 Processing equipment 4 bases 6 Cassette Table 8 cassettes 10 unloading units 12. First transport unit 14 Chuck Table 16 Processing Units 18 Washing Unit 20 Second transport unit 22 Waste liquid treatment equipment 24 cabinets 26 Drainage Channel 28 Water supply channel 30 Input section 32 Display section 34 Frame 36 Waste liquid storage tank 38 Waste liquid supply pump 40,70 Guide rails 42,72 Drip tray 43 Filter Unit 44 First filtration section 46 Inlet 50 Wastewater discharge channel 52 Support plate 54 Clean water storage tank 56 Inlet 62 UV irradiation unit 64 Ion exchange resin section 68 Second filtration section 74 Pure water supply section 76 Controllers 80 Main Unit 82 Interior space 84 Waste liquid 86 Inlet 88 Intake 90 Ultrasonic Oscillator 92,96 Ultrasonic transducer 94 Horn

Claims

1. A storage tank for receiving waste liquid, A filter unit comprising an inlet for receiving the waste liquid, a filter for filtering the waste liquid that flows in from the inlet, and an outlet for discharging the waste liquid filtered by the filter, A waste liquid supply path that supplies the waste liquid from the storage tank to the inlet of the filter unit, A wastewater discharge channel for discharging the wastewater from the outlet of the filter unit, Ultrasonic oscillator and, An ultrasonic transducer connected to the ultrasonic oscillator, A waste liquid treatment apparatus comprising a horn provided in the storage tank and connected to the ultrasonic transducer, which transmits the ultrasonic vibrations generated by the ultrasonic transducer.

2. A contamination detector for detecting the degree of contamination of the waste liquid, It also includes a controller, The waste liquid treatment apparatus according to claim 1, characterized in that the controller controls the ultrasonic oscillator by referring to the degree of contamination of the waste liquid detected by the contamination detector, and adjusts the characteristics of the ultrasonic vibrations generated by the ultrasonic transducer.

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