Water treatment device and water treatment method

Abstract

Provided are a water treatment device and a water treatment method that make it possible to recover ammonia contained in ammonia / hydrogen peroxide-containing water, which contains ammonia and hydrogen peroxide, while reducing the number of pH adjustment steps and the amount of chemicals used. A water treatment device (1) comprises: a hydrogen peroxide decomposition device (12) that decomposes hydrogen peroxide in ammonia / hydrogen peroxide-containing water, which contains ammonia and hydrogen peroxide; and a semipermeable membrane treatment device (5) that uses a semipermeable membrane module (16) having a first space (20) and a second space (22) partitioned by a semipermeable membrane (24) to obtain semipermeable membrane-concentrated water by passing the hydrogen peroxide decomposition-treated water through the first space (20) and causing water contained in the hydrogen peroxide decomposition-treated water to permeate through the semipermeable membrane (24) with the first space (20) pressurized, and obtain semipermeable membrane-diluted water by passing a portion of the hydrogen peroxide decomposition-treated water or at least a portion of the semipermeable membrane-concentrated water through the second space (22).

Description

Water treatment device and water treatment method

[0001] The present invention relates to a water treatment apparatus and a water treatment method for recovering ammonia from ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide.

[0002] Ammonia stripping is a known method for treating ammonia-containing water. The ammonia stripping method involves adjusting the pH of the water to be treated, which contains ammonia (ammonium ions), to, for example, 10 or higher, heating the water to, for example, 80°C or higher, and supplying air to aerate the solution, thereby converting the ammonia into gas and separating and removing it from the water.

[0003] In treating ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide, a method is known, as disclosed in Patent Document 1, in which hydrogen peroxide in the water to be treated is decomposed in an activated carbon tower, the pH is adjusted to about 7, and then concentrated water is obtained by reverse osmosis membrane treatment, and the pH is adjusted to a range of 10.5 to 12 before being subjected to ammonia stripping treatment.

[0004] Patent Document 2 describes a method in which ammonia-containing wastewater is subjected to an ammonia stripping treatment at a pH of 10 or higher, the treated water is subjected to a first-stage reverse osmosis membrane treatment at a pH of 10 or higher, the permeate is then subjected to a second-stage reverse osmosis membrane treatment at a pH of 8.5 or lower, and the resulting concentrated water is circulated to the stage preceding the ammonia stripping treatment.

[0005] However, as in the methods of Patent Documents 1 and 2, ammonia stripping treatment requires the pH of the water to be treated to be 10 or higher, and also requires heat treatment, which can increase the chemical costs for pH adjustment and the energy costs for heating. Furthermore, the methods of Patent Documents 1 and 2 also require pH adjustment during reverse osmosis membrane treatment.

[0006] JP 2001-314872 A JP 2017-051954 A

[0007] An object of the present invention is to provide a water treatment device and a water treatment method that can recover ammonia contained in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide while reducing the number of pH adjustment steps and the amount of chemicals used.

[0008] The present invention provides a water treatment device comprising: hydrogen peroxide decomposition means for decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and semipermeable membrane treatment means for using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, passing hydrogen peroxide decomposed water treated by the hydrogen peroxide decomposition means through the first space and pressurizing the first space to cause water contained in the hydrogen peroxide decomposition treated water to permeate through the semipermeable membrane, thereby obtaining semipermeable membrane concentrated water, and passing a portion of the hydrogen peroxide decomposition treated water or at least a portion of the semipermeable membrane concentrated water through the second space, thereby obtaining semipermeable membrane diluted water.

[0009] The present invention provides a water treatment device comprising: hydrogen peroxide decomposition means for decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and semipermeable membrane treatment means using semipermeable membrane modules connected in multiple stages, each having a first space and a second space separated by a semipermeable membrane, in which hydrogen peroxide decomposition-treated water treated in the hydrogen peroxide decomposition means is passed through the first space of the semipermeable membrane module of a first stage, and the first space is pressurized to cause the water contained in the hydrogen peroxide decomposition-treated water to permeate through the semipermeable membrane, thereby obtaining semipermeable membrane concentrated water, and this concentrated water is further obtained using semipermeable membrane modules of subsequent stages or later to obtain semipermeable membrane concentrated water, and semipermeable membrane diluted water is obtained by passing a portion of the hydrogen peroxide decomposition-treated water, at least a portion of the semipermeable membrane concentrated water, or at least a portion of semipermeable membrane diluted water obtained from another semipermeable membrane module, through the second space of the semipermeable membrane module of each stage.

[0010] In the water treatment device, the ammonium ion concentration in the semipermeable membrane concentrated water is preferably 50,000 mg / L or more.

[0011] It is preferable that the water treatment device does not include an ammonia stripping treatment means.

[0012] The water treatment device preferably further comprises a pH adjusting means for adjusting the pH of the ammonia / hydrogen peroxide-containing water to 5 to 8, upstream of the semipermeable membrane treatment means.

[0013] In the water treatment apparatus, the ammonia / hydrogen peroxide-containing water is preferably wastewater having a pH of 10 or more discharged from a semiconductor factory.

[0014] The present invention is a water treatment method comprising: a hydrogen peroxide decomposition step of decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and a semipermeable membrane treatment step of using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, passing hydrogen peroxide decomposed water treated by the hydrogen peroxide decomposition means through the first space, pressurizing the first space to cause water contained in the hydrogen peroxide decomposition treated water to permeate through the semipermeable membrane to obtain semipermeable membrane concentrated water, and passing a portion of the hydrogen peroxide decomposition treated water or at least a portion of the semipermeable membrane concentrated water through the second space to obtain semipermeable membrane diluted water.

[0015] The present invention is a water treatment method comprising: a hydrogen peroxide decomposition step of decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and a semipermeable membrane treatment step of using semipermeable membrane modules connected in multiple stages, each having a first space and a second space separated by a semipermeable membrane, passing hydrogen peroxide decomposition-treated water treated by the hydrogen peroxide decomposition means through the first space of the semipermeable membrane module of a first stage, pressurizing the first space to cause water contained in the hydrogen peroxide decomposition-treated water to permeate through the semipermeable membrane, thereby obtaining semipermeable membrane concentrated water, and further obtaining semipermeable membrane concentrated water using semipermeable membrane modules of subsequent stages, while passing a portion of the hydrogen peroxide decomposition-treated water, at least a portion of the semipermeable membrane concentrated water, or at least a portion of semipermeable membrane diluted water obtained from another semipermeable membrane module, through the second space of the semipermeable membrane module of each stage to obtain semipermeable membrane diluted water.

[0016] In the water treatment method, the ammonium ion concentration in the semipermeable membrane concentrated water is preferably 50,000 mg / L or more.

[0017] The water treatment method preferably does not include an ammonia stripping treatment step.

[0018] The water treatment method preferably further comprises a pH adjustment step of adjusting the pH of the ammonia / hydrogen peroxide-containing water to 5 to 8 prior to the semipermeable membrane treatment step.

[0019] In the water treatment method, the ammonia / hydrogen peroxide-containing water is preferably wastewater having a pH of 10 or more discharged from a semiconductor factory.

[0020] The present invention provides a water treatment device and a water treatment method that can recover ammonia contained in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide while reducing the number of pH adjustment steps and the amount of chemicals used.

[0021] Fig. 1 is a schematic configuration diagram showing an example of a water treatment device according to an embodiment of the present invention. Fig. 2 is a schematic configuration diagram showing another example of a water treatment device according to an embodiment of the present invention. Fig. 3 is a schematic configuration diagram showing another example of a semipermeable membrane treatment device in a water treatment device according to an embodiment of the present invention. Fig. 4 is a schematic configuration diagram showing another example of a semipermeable membrane treatment device in a water treatment device according to an embodiment of the present invention. Fig. 5 is a schematic configuration diagram showing another example of a semipermeable membrane treatment device in a water treatment device according to an embodiment of the present invention.

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes an embodiment of the present invention. The embodiment is an example of implementing the present invention, and the present invention is not limited to the embodiment.

[0023] An example of a water treatment device according to an embodiment of the present invention is outlined in Fig. 1, and its configuration will be described below. The water treatment device 1 shown in Fig. 1 is a device that decomposes hydrogen peroxide in ammonia / hydrogen peroxide-containing water and then treats the hydrogen peroxide-decomposed water using a semipermeable membrane.

[0024] The water treatment device 1 uses a hydrogen peroxide decomposition device 12 as hydrogen peroxide decomposition means for decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide, and a semipermeable membrane module 16 having a first space 20 and a second space 22 separated by a semipermeable membrane 24, and is equipped with a semipermeable membrane treatment device 5 as semipermeable membrane treatment means for passing hydrogen peroxide decomposition-treated water treated in the hydrogen peroxide decomposition device 12 through the first space 20 and pressurizing the first space 20 to cause the water contained in the hydrogen peroxide decomposition-treated water to permeate through the semipermeable membrane 24, thereby obtaining semipermeable membrane concentrated water, and for passing a portion of the hydrogen peroxide decomposition-treated water or at least a portion of the semipermeable membrane concentrated water through the second space 22, thereby obtaining semipermeable membrane diluted water.

[0025] The water treatment device 1 may include a water tank 10 for treatment that stores ammonia / hydrogen peroxide-containing water, and a membrane-supply water tank 14 for storing hydrogen peroxide decomposition-treated water.

[0026] In the water treatment device 1 of Figure 1, a water to be treated pipe 30 is connected to the inlet of the water tank 10 to be treated. The outlet of the water tank 10 to be treated and the inlet of the hydrogen peroxide decomposition device 12 are connected by a water to be treated supply pipe 32. The outlet of the hydrogen peroxide decomposition device 12 and the inlet of the membrane supply tank 14 are connected by a hydrogen peroxide decomposition treated water pipe 34. The outlet of the membrane supply tank 14 and the inlet of the first space 20 of the semipermeable membrane module 16 are connected by a semipermeable membrane treated water supply pipe 36. A semipermeable membrane concentrated water pipe 38 is connected to the outlet of the first space 20 of the semipermeable membrane module 16. A semipermeable membrane concentrated water pipe 40 branching from the semipermeable membrane concentrated water pipe 38 is connected to the inlet of the second space 22 of the semipermeable membrane module 16. A semipermeable membrane diluted water pipe 42 is connected to the outlet of the second space 22 of the semipermeable membrane module 16. A pH adjuster addition pipe 44 is connected to the pH adjuster inlet of the treated water tank 10 as a pH adjustment means for adjusting the pH of the ammonia / hydrogen peroxide-containing water by adding a pH adjuster to the ammonia / hydrogen peroxide-containing water.

[0027] The semipermeable membrane module 16 has a first space 20 (concentration side) and a second space 22 (permeation side) separated by a semipermeable membrane 24, and is an apparatus in which hydrogen peroxide decomposition-treated water is passed through the first space 20 from the first space inlet of the semipermeable membrane module 16, and at least a portion of the semipermeable membrane concentrate water discharged from the first space outlet of the first space 20 of the semipermeable membrane module 16 is passed through the second space inlet of the semipermeable membrane module 16 to the second space 22, thereby pressurizing the first space 20, causing the water contained in the hydrogen peroxide decomposition-treated water in the first space 20 to permeate into the second space 22 through the semipermeable membrane 24, thereby concentrating the water. That is, in the water treatment device 1, the hydrogen peroxide decomposition-treated water is concentrated using the semipermeable membrane 24. The semipermeable membrane module 16 is an apparatus in which hydrogen peroxide decomposition-treated water is supplied to the first space 20 of the semipermeable membrane module 16, and at least a portion of the semipermeable membrane concentrate water obtained from the outlet of the first space 20 is supplied to the second space 22 of the semipermeable membrane module 16, thereby performing a concentration treatment.

[0028] The water treatment method and the operation of the water treatment device 1 according to this embodiment will be described.

[0029] Ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide is stored in the water tank 10 as needed through the water to be treated piping 30, and is supplied to the hydrogen peroxide decomposition device 12 through the water to be treated supply piping 32. Here, in the water to be treated tank 10, a pH adjuster may be added to the ammonia / hydrogen peroxide-containing water through pH adjuster addition piping 44 to adjust the pH of the ammonia / hydrogen peroxide-containing water within a predetermined range (pH adjustment step). The pH adjuster may be added in the water to be treated piping 30, the water to be treated supply piping 32, or the hydrogen peroxide decomposition device 12.

[0030] In the hydrogen peroxide decomposition device 12, a hydrogen peroxide decomposition process is performed on the ammonia / hydrogen peroxide-containing water, and the hydrogen peroxide in the ammonia / hydrogen peroxide-containing water is decomposed (hydrogen peroxide decomposition step). The hydrogen peroxide decomposition-treated water obtained in the hydrogen peroxide decomposition step is stored in the membrane supply tank 14 as needed and is pressurized and fed through the semipermeable membrane treated water supply pipe 36 from the first space inlet of the semipermeable membrane module 16 to the first space 20. The semipermeable membrane treated water supply pipe 36 may be provided with a pressure pump that pressurizes and supplies the hydrogen peroxide decomposition-treated water in the membrane supply tank 14 from the first space inlet of the semipermeable membrane module 16 to the first space 20. A portion of the water contained in the pressurized hydrogen peroxide decomposition-treated water permeates through the semipermeable membrane 24 from the first space 20 to the second space 22. At this time, most of the ions and the like cannot permeate the semipermeable membrane 24, so the water in the first space 20 that did not permeate the semipermeable membrane 24 is concentrated. On the other hand, in the second space 22, a part of the semipermeable membrane concentrated water passed through the semipermeable membrane concentrated water pipes 38, 40 and the permeated water with a low ion concentration that has permeated the semipermeable membrane 24 join together, thereby producing a dilution effect. The semipermeable membrane concentrated water obtained in the first space 20 is discharged from the first space outlet through the semipermeable membrane concentrated water pipe 38, and at least a part of the semipermeable membrane concentrated water is sent through the semipermeable membrane concentrated water pipe 40 branched from the semipermeable membrane concentrated water pipe 38 to the second space inlet of the semipermeable membrane module 16 and passed through (semipermeable membrane treatment step).

[0031] The semipermeable membrane concentrated water discharged from the first space 20 is discharged outside the system and recovered or discarded.

[0032] The semipermeable membrane diluted water obtained in the second space 22 is discharged from the second space outlet through the semipermeable membrane diluted water piping 42 to the outside of the system and may be recovered, discarded, or reused, or may be stored in a semipermeable membrane diluted water tank as needed and further treated in accordance with the water quality, for example, by being sent to a reverse osmosis membrane treatment device or a nano (NF) filtration membrane treatment device for further reverse osmosis membrane treatment and nano (NF) filtration membrane treatment, or may be subjected to additional treatment such as water recovery, discharge, UV treatment, etc. The semipermeable membrane diluted water may be returned to the upstream stage of the semipermeable membrane treatment device 5, or, if a reverse osmosis membrane treatment device or a nano (NF) filtration membrane treatment device is provided upstream of the semipermeable membrane treatment device 5 as described below, may be returned to the upstream stage of the reverse osmosis membrane treatment device or nano (NF) filtration membrane treatment device.

[0033] In this way, by having a hydrogen peroxide decomposition means (step) that decomposes hydrogen peroxide in ammonia / hydrogen peroxide-containing water and a semipermeable membrane treatment means (step) that treats the hydrogen peroxide decomposition-treated water using a semipermeable membrane, the amount of hydrogen peroxide is reduced from the ammonia / hydrogen peroxide-containing water to be treated, and semipermeable membrane concentrated water in which ammonia has been concentrated to a high concentration and reduced in volume is recovered.

[0034] The water treatment method and water treatment device according to this embodiment do not necessarily include an ammonia stripping treatment means (step). Ammonia can be recovered as a valuable resource by concentrating ammonia to a high concentration using a semipermeable membrane treatment device, eliminating the need for ammonia stripping treatment. This reduces the number of pH adjustment locations and the chemical costs required for pH adjustment. Furthermore, the reduction in the amount of pH adjustment chemicals added also reduces impurities in the valuable resource.

[0035] The ammonia / hydrogen peroxide-containing water to be treated is water containing ammonia and hydrogen peroxide, and is not particularly limited, but examples thereof include wastewater discharged from semiconductor factories. Examples of wastewater discharged from semiconductor factories include wafer cleaning wastewater with a pH of 10 or higher. Because wastewater from semiconductor factories contains few impurities, the water treatment method and water treatment device according to this embodiment can be suitably applied.

[0036] The ammonium ion concentration in the ammonia / hydrogen peroxide-containing water to be treated is, for example, in the range of 500 to 3000 mg / L, and the hydrogen peroxide concentration is, for example, in the range of 500 to 2000 mg / L.

[0037] The pH adjustment of the ammonia / hydrogen peroxide-containing water may be performed by adding a pH adjuster in the stage preceding the semipermeable membrane treatment device 5 (semipermeable membrane treatment step), for example, in the water tank 10 to be treated as shown in Figure 1, or by adding a pH adjuster in the water pipe 30 to be treated, the water supply pipe 32 to be treated, the hydrogen peroxide decomposition treated water pipe 34, or the semipermeable membrane treated water supply pipe 36. Furthermore, the pH adjustment of the ammonia / hydrogen peroxide-containing water may be performed in the hydrogen peroxide decomposition device 12 (hydrogen peroxide decomposition step) or in the membrane supply water tank 14.

[0038] The pH of the ammonia / hydrogen peroxide-containing water may be adjusted to a range of 5 to 8, and preferably to a range of 5 to 7. If the pH of the ammonia / hydrogen peroxide-containing water is less than 5, the concentration performance of the semipermeable membrane in the subsequent stage may be reduced, and if it exceeds 8, the concentration performance of the ammonia to be concentrated in the semipermeable membrane treatment may be reduced.

[0039] Examples of pH adjusters used for adjusting the pH include acids such as hydrochloric acid and sulfuric acid, and alkalis such as aqueous sodium hydroxide solution.

[0040] For example, at least one of the treated water tank 10, the treated water piping 30, the treated water supply piping 32, and the hydrogen peroxide decomposition device 12 may be equipped with a pH measuring device as a pH measuring means for measuring the pH of the ammonia / hydrogen peroxide-containing water, and the pH of the ammonia / hydrogen peroxide-containing water may be measured (pH measurement process).

[0041] The temperature of the ammonia / hydrogen peroxide-containing water may be adjusted before the hydrogen peroxide decomposition device 12 (hydrogen peroxide decomposition step). The temperature of the ammonia / hydrogen peroxide-containing water may be, for example, in the range of 10 to 40°C, and preferably in the range of 15 to 30°C.

[0042] For example, at least one of the treated water tank 10, the treated water piping 30, the treated water supply piping 32, and the hydrogen peroxide decomposition device 12 may be provided with a heater or the like as a water temperature adjustment means for adjusting the temperature of the ammonia / hydrogen peroxide-containing water (water temperature adjustment step). There are no particular restrictions on the location of the water temperature adjustment means (step), as long as it is located upstream of the semipermeable membrane treatment device (step). Furthermore, if a pretreatment device (step), such as a reverse osmosis membrane treatment device (step), is located upstream of the semipermeable membrane treatment device (step), it is preferable to provide the water temperature adjustment means (step) upstream of the pretreatment device (step).

[0043] The ammonia / hydrogen peroxide-containing water may be pumped to the hydrogen peroxide decomposition device 12. For example, a pump may be provided in the untreated water supply pipe 32 to send the water.

[0044] The hydrogen peroxide decomposition device 12 is not particularly limited as long as it can decompose hydrogen peroxide, but examples include activated carbon treatment, reducing agent treatment using a reducing agent such as sodium bisulfite or sodium thiosulfate, metal oxide treatment using a metal oxide such as manganese oxide, cobalt oxide or copper oxide or a metal oxide supported on a carrier, and enzyme treatment using an enzyme such as catalase.

[0045] In the case of enzyme treatment, two or more hydrogen peroxide decomposition tanks may be used for the enzyme treatment in order to ensure reaction time.

[0046] A dispersant such as an acrylic acid-based chelating agent may be added to the hydrogen peroxide decomposition-treated water obtained in the hydrogen peroxide decomposition device 12 in the upstream stage of the semipermeable membrane treatment device 5 to suppress precipitation of scale components. Furthermore, a bactericide such as hypochlorous acid or a stabilized hypobromous acid composition containing a bromine-based oxidizing agent and a sulfamic acid compound may be added to the hydrogen peroxide decomposition-treated water in the upstream stage of the semipermeable membrane treatment device 5 to suppress the generation of slime. A flocculant may be added to the hydrogen peroxide decomposition-treated water, and the pH of the hydrogen peroxide decomposition-treated water may be adjusted.

[0047] The pH of the hydrogen peroxide decomposition treated water may be adjusted to a range of 5 to 8, preferably 5 to 7. If the pH of the hydrogen peroxide decomposition treated water is less than 5, the concentration performance of the semipermeable membrane in the subsequent stage may be reduced, and if it exceeds 8, the concentration performance of the ammonia to be concentrated in the semipermeable membrane treatment may be reduced.

[0048] The dispersant, bactericide, flocculant, or pH adjuster may be added to the hydrogen peroxide decomposition treated water flowing out of the hydrogen peroxide decomposition device 12, and the addition location may be the membrane supply water tank 14 or the semipermeable membrane treated water supply pipe 36.

[0049] The hydrogen peroxide concentration of the hydrogen peroxide decomposition-treated water obtained in the hydrogen peroxide decomposition device 12 and passed through the semipermeable membrane module 16 of the semipermeable membrane treatment device is, for example, 10 mg / L or less.

[0050] The first space 20 side of the semipermeable membrane module 16 is pressurized, for example, to 0.1 MPa or more, preferably in the range of 1 to 7 MPa, and the permeated water moves into the second space 22 .

[0051] A pressure pump may be used as a pressurizing means for passing water through the first space 20 of the semipermeable membrane module 16 and pressurizing the first space 20. The pressure pump is, for example, a pump that is driven at a rotational speed corresponding to an input drive frequency, and sucks in hydrogen peroxide decomposition treated water and discharges it under pressure to the semipermeable membrane module 16. The pressure pump may be equipped with, for example, an inverter that outputs a drive frequency corresponding to an input command signal to the pressure pump.

[0052] Examples of the semipermeable membrane 24 included in the semipermeable membrane module 16 include a reverse osmosis membrane (RO membrane), a forward osmosis membrane (FO membrane), a nanofiltration membrane (NF membrane), etc. The semipermeable membrane is preferably a reverse osmosis membrane.

[0053] The material for forming the semipermeable membrane 24 is not particularly limited, but examples thereof include cellulose-based resins such as cellulose acetate-based resins, polysulfone-based resins such as polyethersulfone-based resins, and polyamide-based resins.

[0054] The shape of the semipermeable membrane 24 may be a flat membrane, a hollow fiber membrane, a spiral membrane, etc. A hollow fiber membrane is preferred because it allows the surface area of ​​the semipermeable membrane to be increased.

[0055] The ammonium ion concentration of the semipermeable membrane concentrated water obtained in the semipermeable membrane module 16 is, for example, 50,000 mg / L or more, and preferably in the range of 60,000 mg / L or more and 120,000 mg / L or less. If the concentration is in this range, it is possible to reduce the energy required for concentrating the water to a high concentration suitable for recovering valuable materials.

[0056] Sulfuric acid may be added to the semipermeable membrane concentrated water obtained in the semipermeable membrane module 16 to recover ammonium ions as ammonium sulfate.

[0057] A membrane treatment device (membrane treatment process) having two or more different types of rejection performance, such as rejection rates, or different water permeabilities, such as water permeabilities, may be provided upstream of the semipermeable membrane treatment device 5, for example, downstream of the hydrogen peroxide decomposition device 12 and upstream of the semipermeable membrane treatment device 5. Examples of membrane treatment devices (processes) include reverse osmosis membrane treatment devices (reverse osmosis membrane treatment processes) and nanofiltration membrane treatment devices (nanofiltration membrane treatment processes), and combinations of these may also be used, with no particular restrictions on the order of combination. If the hydrogen peroxide decomposition-treated water contains a large amount of components that clog the reverse osmosis membrane, a nanofiltration membrane treatment device may be provided, or a nanofiltration membrane treatment device and a reverse osmosis membrane treatment device may be provided in this order.

[0058] When a reverse osmosis membrane treatment device (reverse osmosis membrane treatment process) is combined with a nanofiltration membrane treatment device (nanofiltration membrane treatment process), the water to be treated supplied to the semipermeable membrane treatment device 5 may be concentrated water from the reverse osmosis membrane treatment or concentrated water from the nanofiltration membrane treatment.

[0059] One or more treatments among a filtration treatment device, a coagulation sedimentation treatment device, a pressure flotation treatment device, a microfiltration membrane (MF membrane) treatment device, an ultrafiltration membrane (UF membrane) treatment device, a biological treatment device, and a softening treatment device may be further provided upstream of the semipermeable membrane treatment device 5, for example, downstream of the hydrogen peroxide decomposition device 12 and upstream of the semipermeable membrane treatment device 5.

[0060] FIG. 2 shows a schematic configuration of an example of a water treatment device in which a reverse osmosis membrane treatment device is provided in the upstream stage of the semipermeable membrane treatment device 5.

[0061] The water treatment device 3 shown in FIG. 2 decomposes hydrogen peroxide in ammonia / hydrogen peroxide-containing water, passes the hydrogen peroxide-decomposed water through a reverse osmosis membrane treatment device, and treats reverse osmosis membrane-concentrated water discharged from the reverse osmosis membrane treatment device with a semipermeable membrane.

[0062] The water treatment device 3 comprises: a hydrogen peroxide decomposition device 12 as hydrogen peroxide decomposition means for decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; a reverse osmosis membrane treatment device 18 as reverse osmosis membrane treatment means for performing reverse osmosis membrane treatment on the hydrogen peroxide decomposition-treated water treated in the hydrogen peroxide decomposition device 10 to obtain reverse osmosis membrane permeate and reverse osmosis membrane concentrate; and a semipermeable membrane treatment device 5 as semipermeable membrane treatment means for using a semipermeable membrane module 16 having a first space 20 and a second space 22 separated by a semipermeable membrane 24 to pass the reverse osmosis membrane concentrate obtained by the reverse osmosis membrane treatment of the hydrogen peroxide decomposition-treated water through the first space 20 and pressurize the first space 20 to cause the water contained in the reverse osmosis membrane concentrate obtained by the reverse osmosis membrane treatment of the hydrogen peroxide decomposition-treated water to permeate through the semipermeable membrane 24, thereby obtaining semipermeable membrane concentrate, and for passing a portion of the reverse osmosis membrane concentrate or at least a portion of the semipermeable membrane concentrate into the second space 22 to obtain semipermeable membrane diluted water.

[0063] The water treatment device 3 may include a water tank 10 for treatment that stores ammonia / hydrogen peroxide-containing water, and a membrane-supply water tank 14 for storing hydrogen peroxide decomposition-treated water.

[0064] In the water treatment device 3 of Figure 2, a water to be treated pipe 30 is connected to the inlet of the water tank 10 to be treated. The outlet of the water tank 10 to be treated and the inlet of the hydrogen peroxide decomposition device 12 are connected by a water to be treated supply pipe 32. The outlet of the hydrogen peroxide decomposition device 12 and the inlet of the membrane supply tank 14 are connected by a hydrogen peroxide decomposition treated water pipe 34. The outlet of the membrane supply tank 14 and the inlet of the reverse osmosis membrane treatment device 18 are connected by a hydrogen peroxide decomposition treated water supply pipe 46. A reverse osmosis membrane permeate pipe 48 is connected to the reverse osmosis membrane permeate outlet of the reverse osmosis membrane treatment device 18. A reverse osmosis membrane concentrated water outlet of the reverse osmosis membrane treatment device 18 is connected to the inlet of the first space 20 of the semipermeable membrane module 16 by a semipermeable membrane treated water supply pipe 36. A semipermeable membrane concentrated water pipe 38 is connected to the outlet of the first space 20 of the semipermeable membrane module 16. A semipermeable membrane concentrated water pipe 40 branched from the semipermeable membrane concentrated water pipe 38 is connected to the inlet of the second space 22 of the semipermeable membrane module 16. A semipermeable membrane diluted water pipe 42 is connected to the outlet of the second space 22 of the semipermeable membrane module 16. A pH adjuster addition pipe 44 is connected to the pH adjuster inlet of the water tank 10 to serve as pH adjustment means for adding a pH adjuster to the ammonia / hydrogen peroxide-containing water to adjust the pH of the ammonia / hydrogen peroxide-containing water.

[0065] The semipermeable membrane module 16 has a first space 20 (concentration side) and a second space 22 (permeation side) separated by a semipermeable membrane 24, and is an apparatus in which reverse osmosis membrane concentrated water obtained by reverse osmosis membrane treatment of hydrogen peroxide decomposition treated water is passed through the first space inlet of the semipermeable membrane module 16 into the first space 20, and at least a portion of the semipermeable membrane concentrated water discharged from the first space outlet of the first space 20 of the semipermeable membrane module 16 is passed through the second space inlet of the semipermeable membrane module 16 into the second space 22, and by pressurizing the first space 20, water contained in the reverse osmosis membrane concentrated water in the first space 20 is permeated into the second space 22 through the semipermeable membrane 24, thereby concentrating the water. That is, in the water treatment device 1, the reverse osmosis membrane concentrated water obtained by reverse osmosis membrane treatment of the hydrogen peroxide decomposition treated water is concentrated using the semipermeable membrane 24. The semipermeable membrane module 16 is an apparatus for performing a concentration treatment by supplying reverse osmosis membrane concentrated water obtained by reverse osmosis membrane treatment of hydrogen peroxide decomposition treated water to a first space 20 of the semipermeable membrane module 16 and supplying at least a portion of the semipermeable membrane concentrated water obtained from the outlet of the first space 20 to a second space 22 of the semipermeable membrane module 16.

[0066] Ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide is stored in the water to be treated tank 10 as needed through the water to be treated piping 30, and is supplied to the hydrogen peroxide decomposition device 12 through the water to be treated supply piping 32. In the water to be treated tank 10, a pH adjuster may be added to the ammonia / hydrogen peroxide-containing water through pH adjuster addition piping 44 to adjust the pH of the ammonia / hydrogen peroxide-containing water within a predetermined range (pH adjustment step). The pH adjuster may be added in the water to be treated piping 30, the water to be treated supply piping 32, the hydrogen peroxide decomposition-treated water piping 34, the hydrogen peroxide decomposition-treated water supply piping 46, the semipermeable membrane-treated water supply piping 36, the hydrogen peroxide decomposition device 12, or the membrane supply water tank 14.

[0067] In the hydrogen peroxide decomposition device 12, a hydrogen peroxide decomposition process is performed on the ammonia / hydrogen peroxide-containing water, and the hydrogen peroxide in the ammonia / hydrogen peroxide-containing water is decomposed (hydrogen peroxide decomposition step). The hydrogen peroxide decomposition-treated water obtained in the hydrogen peroxide decomposition step is stored in the membrane supply tank 14 as needed and sent to the reverse osmosis membrane treatment device 18 through the hydrogen peroxide decomposition-treated water supply piping 46. In the reverse osmosis membrane treatment device 18, the hydrogen peroxide decomposition-treated water is subjected to reverse osmosis membrane treatment using a reverse osmosis membrane, and reverse osmosis membrane permeate and reverse osmosis membrane concentrate are obtained (reverse osmosis membrane treatment step). The reverse osmosis membrane permeate obtained by the reverse osmosis membrane treatment is discharged through the reverse osmosis membrane permeate piping 48.

[0068] The reverse osmosis membrane concentrated water obtained by the reverse osmosis membrane treatment is pressurized and fed from the first space inlet of the semipermeable membrane module 16 to the first space 20 through the semipermeable membrane treated water supply pipe 36. A pressure pump may be provided in the semipermeable membrane treated water supply pipe 36 to pressurize and feed the reverse osmosis membrane concentrated water from the first space inlet of the semipermeable membrane module 16 to the first space 20. A portion of the water contained in the pressurized reverse osmosis membrane concentrated water permeates from the first space 20 to the second space 22 through the semipermeable membrane 24. At this time, most ions and the like cannot permeate the semipermeable membrane 24, so the water in the first space 20 that did not permeate the semipermeable membrane 24 is concentrated. Meanwhile, in the second space 22, a portion of the semipermeable membrane concentrated water passed through the semipermeable membrane concentrated water pipes 38, 40 and the permeate with a low ion concentration that permeated the semipermeable membrane 24 join together, resulting in a dilution effect. The semipermeable membrane concentrated water obtained in the first space 20 is discharged from the first space outlet through a semipermeable membrane concentrated water pipe 38, and at least a part of the semipermeable membrane concentrated water is sent through a semipermeable membrane concentrated water pipe 40 branched from the semipermeable membrane concentrated water pipe 38 to the second space 22 from the second space inlet of the semipermeable membrane module 16, and is passed through (semipermeable membrane treatment process).

[0069] The semipermeable membrane concentrated water discharged from the first space 20 is discharged outside the system and recovered or discarded.

[0070] The semipermeable membrane diluted water obtained in the second space 22 is discharged from the second space outlet through the semipermeable membrane diluted water piping 42 to the outside of the system and may be recovered, discarded, or reused, or may be stored in a semipermeable membrane diluted water tank as needed and further treated in accordance with the water quality, for example, sent to a reverse osmosis membrane treatment device or a nano (NF) filtration membrane treatment device for further reverse osmosis membrane treatment and nano (NF) filtration membrane treatment, or may be subjected to additional treatment such as water recovery, discharge, UV treatment, etc. The semipermeable membrane diluted water may be returned to a stage upstream of the semipermeable membrane treatment device 5, or may be returned to a stage upstream of the reverse osmosis membrane treatment device 18.

[0071] In this way, by having a hydrogen peroxide decomposition means (step) that decomposes hydrogen peroxide in ammonia / hydrogen peroxide-containing water, a reverse osmosis membrane treatment means (step) that treats the hydrogen peroxide decomposition-treated water using a reverse osmosis membrane, and a semipermeable membrane treatment means (step) that treats the reverse osmosis membrane-concentrated water using a semipermeable membrane, the amount of hydrogen peroxide is reduced from the ammonia / hydrogen peroxide-containing water to be treated, and semipermeable membrane-concentrated water in which the ammonia has been further concentrated to a higher concentration and reduced in volume is recovered.

[0072] In the water treatment device 1 shown in Fig. 1 and the water treatment device 3 shown in Fig. 2, the semipermeable membrane treatment device may be configured so that a portion of the hydrogen peroxide decomposition-treated water or reverse osmosis membrane-concentrated water obtained by reverse osmosis membrane treatment of the hydrogen peroxide decomposition-treated water passes through the second space 22. An example of such a semipermeable membrane treatment device is shown in Fig. 3.

[0073] In the semipermeable membrane treatment device 6 of Fig. 3, a semipermeable membrane treatment water supply pipe 36 from the membrane supply tank 14 as in Fig. 1 or a semipermeable membrane treatment water supply pipe 36 from the reverse osmosis membrane treatment device 18 as in Fig. 2 is connected to the first space inlet of the semipermeable membrane module 16, and a semipermeable membrane treatment water supply pipe 37 branched from the semipermeable membrane treatment water supply pipe 36 is connected to the second space inlet of the semipermeable membrane module 16. A semipermeable membrane concentrated water pipe 38 is connected to the first space outlet of the semipermeable membrane module 16, and a semipermeable membrane diluted water pipe 43 is connected to the second space outlet of the semipermeable membrane module 16.

[0074] The semipermeable membrane module 16 has a first space 20 (concentration side) and a second space 22 (permeation side) separated by a semipermeable membrane 24. Hydrogen peroxide decomposition-treated water or reverse osmosis membrane-concentrated water obtained by reverse osmosis membrane treatment of the hydrogen peroxide decomposition-treated water is passed through the first space 20 from the first space inlet of the semipermeable membrane module 16 and through the second space inlet of the second space 22. By pressurizing the first space 20, the water contained in the hydrogen peroxide decomposition-treated water or reverse osmosis membrane-concentrated water in the first space 20 is permeated into the second space 22 via the semipermeable membrane 24, thereby concentrating the water. That is, in the semipermeable membrane treatment device 6, the hydrogen peroxide decomposition-treated water or reverse osmosis membrane-concentrated water is concentrated using the semipermeable membrane 24. The semipermeable membrane treatment device 6 is a device that performs a concentration treatment by supplying the hydrogen peroxide decomposition-treated water or reverse osmosis membrane-concentrated water to both the first space 20 and the second space 22 of the semipermeable membrane module 16.

[0075] The hydrogen peroxide decomposition-treated water or the reverse osmosis membrane-concentrated water obtained by the reverse osmosis membrane treatment of the hydrogen peroxide decomposition-treated water is pressurized and fed from the first space inlet of the semipermeable membrane module 16 to the first space 20 through the semipermeable membrane treated water supply pipe 36. A portion of the water contained in the pressurized hydrogen peroxide decomposition-treated water or the reverse osmosis membrane-concentrated water permeates from the first space 20 to the second space 22 through the semipermeable membrane 24. At this time, most ions and the like cannot permeate the semipermeable membrane 24, so the water in the first space 20 that did not permeate the semipermeable membrane 24 is concentrated. Meanwhile, in the second space 22, a portion of the hydrogen peroxide decomposition-treated water or the reverse osmosis membrane-concentrated water fed through the semipermeable membrane treated water supply pipe 37 joins with the permeate with a low ion concentration that permeated the semipermeable membrane 24, resulting in a dilution effect. The semipermeable membrane-concentrated water obtained in the first space 20 is discharged from the first space outlet through the semipermeable membrane concentrated water pipe 38 (semipermeable membrane treatment process).

[0076] The semipermeable membrane diluted water obtained in the second space 22 may be discharged from the second space outlet through the semipermeable membrane diluted water piping 43, and may further be subjected to other treatments as described above depending on the water quality, etc.

[0077] In the water treatment method and water treatment device according to this embodiment, a semipermeable membrane treatment device having a multistage semipermeable membrane module may be used. An example of a semipermeable membrane treatment device having such a configuration is shown in Figure 4. The semipermeable membrane treatment device 7 shown in Figure 4 has a structure in which semipermeable membrane modules are combined in series in three stages, and is a device that passes water through the first space side and the second space side in series.

[0078] The semipermeable membrane treatment device 7 shown in FIG. 4 uses semipermeable membrane modules 16 connected in multiple stages, each having a first space 20 (concentration side) and a second space 22 (permeation side) separated by a semipermeable membrane 24, and in which hydrogen peroxide decomposition treated water or reverse osmosis membrane concentrated water obtained by reverse osmosis membrane treatment of the hydrogen peroxide decomposition treated water is passed through the first space 20 of the first-stage semipermeable membrane module 16, and the first space 20 is pressurized to cause the water contained in the hydrogen peroxide decomposition treated water or the reverse osmosis membrane concentrated water to permeate through the semipermeable membrane 24, thereby obtaining semipermeable membrane concentrated water. This semipermeable membrane concentrated water is further obtained using the semipermeable membrane modules 16 in the next stage or later, and at least a portion of the semipermeable membrane concentrated water is passed through the second space 22 of the semipermeable membrane module 16 in each stage to obtain semipermeable membrane diluted water. For example, the semipermeable membrane treatment means includes a first-stage semipermeable membrane module 16a, a second-stage semipermeable membrane module 16b, and a third-stage semipermeable membrane module 16c. Each semipermeable membrane module has a first space 20 and a second space 22 separated by a semipermeable membrane 24. The semipermeable membrane module 16 is an apparatus in which hydrogen peroxide decomposition treated water or reverse osmosis membrane concentrated water is supplied to the first space of the first-stage membrane module, and the semipermeable membrane concentrated water is sequentially supplied to the first space 20 of the next-stage membrane module for concentration treatment.

[0079] In the semipermeable membrane treatment device 7 of Figure 4, a semipermeable membrane treatment water supply pipe 36 from the membrane supply tank 14 as in Figure 1 or a semipermeable membrane treatment water supply pipe 36 from the reverse osmosis membrane treatment device 18 as in Figure 2 is connected to the first space inlet of the first-stage semipermeable membrane module 16a. The first space outlet of the first-stage semipermeable membrane module 16a and the first space inlet of the second-stage semipermeable membrane module 16b are connected by a semipermeable membrane concentrated water pipe 50. The first space outlet of the second-stage semipermeable membrane module 16b and the first space inlet of the third-stage semipermeable membrane module 16c are connected by a semipermeable membrane concentrated water pipe 52. A semipermeable membrane concentrated water pipe 54 is connected to the first space outlet of the third-stage semipermeable membrane module 16c. A semipermeable membrane concentrated water pipe 56 branched from the semipermeable membrane concentrated water pipe 54 is connected to the first space inlet of the third-stage semipermeable membrane module 16c. The second space outlet of the third-stage semipermeable membrane module 16c and the second space inlet of the second-stage semipermeable membrane module 16b are connected by a semipermeable membrane dilution water piping 58. The second space outlet of the second-stage semipermeable membrane module 16b and the second space inlet of the first-stage semipermeable membrane module 16a are connected by a semipermeable membrane dilution water piping 60. A semipermeable membrane dilution water piping 62 is connected to the second space outlet of the first-stage semipermeable membrane module 16a.

[0080] The semipermeable membrane module 16 is a device that uses a multistage membrane module having a first space 20 and a second space 22 separated by a semipermeable membrane 24, and supplies hydrogen peroxide decomposition treated water or reverse osmosis membrane concentrated water obtained by reverse osmosis membrane treatment of the hydrogen peroxide decomposition treated water to the first space 20a of the first-stage semipermeable membrane module 16a, and passes this semipermeable membrane concentrated water in series to the first space 20 of the semipermeable membrane module 16 of the next stage, and supplies at least a portion of the semipermeable membrane concentrated water of the final-stage semipermeable membrane module 16c to its own second space 22c, and passes the resulting semipermeable membrane diluted water in series to the second space 22 of the semipermeable membrane module 16 of the previous stage, and by pressurizing the first space 20 of each stage, the water contained in the first space 20 is permeated into the second space 22 via the semipermeable membrane 24, thereby concentrating the water. That is, in the semipermeable membrane module 16, the hydrogen peroxide decomposition treated water or the reverse osmosis membrane concentrated water is concentrated using the semipermeable membrane 24, and the semipermeable membrane concentrated water is further concentrated using the semipermeable membrane 24 in the next stage.

[0081] The hydrogen peroxide decomposition treated water or the reverse osmosis membrane concentrated water obtained by the reverse osmosis membrane treatment of the hydrogen peroxide decomposition treated water is sent to the first space 20a of the first-stage semipermeable membrane module 16a through the semipermeable membrane treated water supply pipe 36. Meanwhile, the semipermeable membrane dilution water sent through the second space 22c of the third-stage semipermeable membrane module 16c and the second space 22b of the second-stage semipermeable membrane module 16b (described later) is sent to the second space 22a of the first-stage semipermeable membrane module 16a through the semipermeable membrane dilution water pipe 60. In the first-stage semipermeable membrane module 16a, the first space 20a is pressurized, and the water contained in the first space 20a permeates into the second space 22a through the semipermeable membrane 24a (concentration step (first stage)), and the semipermeable membrane diluted water is obtained in the second space 22a (dilution step (first stage)). The semipermeable membrane concentrated water obtained in the first space 20a of the first-stage semipermeable membrane module 16a is sent to the first space 20b of the second-stage semipermeable membrane module 16b through the semipermeable membrane concentrated water piping 50. The semipermeable membrane diluted water obtained in the second space 22a of the first-stage semipermeable membrane module 10a is discharged from the second space outlet through the semipermeable membrane diluted water piping 62.

[0082] In the second-stage semipermeable membrane module 16b, the semipermeable membrane dilution water sent via the second space 22c of the third-stage semipermeable membrane module 16c (described later) is sent to the second space 22b of the second-stage semipermeable membrane module 16b through the semipermeable membrane dilution water piping 58. The first space 20b is pressurized, and the water contained in the first space 20b is permeated into the second space 22b through the semipermeable membrane 24b (concentration step (second stage)), and semipermeable membrane dilution water is obtained in the second space 22b (dilution step (second stage)). The semipermeable membrane concentrated water obtained in the first space 20b of the second-stage semipermeable membrane module 16b is sent to the first space 20c of the third-stage semipermeable membrane module 16c through the semipermeable membrane concentrated water piping 52. The semipermeable membrane dilution water obtained in the second space 22b of the second-stage semipermeable membrane module 16b is sent through the semipermeable membrane dilution water piping 60 to the second space 22a of the first-stage semipermeable membrane module 16a.

[0083] In the third-stage semipermeable membrane module 16c, the semipermeable membrane concentrated water obtained in the first space 20c of the third-stage semipermeable membrane module 16c is sent to the second space 22c through the semipermeable membrane concentrated water pipes 54, 56 as described below. The first space 20c is pressurized, and the water contained in the first space 20c is permeated into the second space 22c through the semipermeable membrane 24c (concentration process (third stage)), and semipermeable membrane diluted water is obtained in the second space 22c (dilution process (third stage)) (these are referred to as semipermeable membrane treatment processes). The semipermeable membrane concentrated water obtained in the first space 20c of the third-stage semipermeable membrane module 16c is discharged through the semipermeable membrane concentrated water pipe 54. The semipermeable membrane concentrated water branched off from the semipermeable membrane concentrated water pipe 54 is sent to the second space 22c of the third-stage semipermeable membrane module 16c through the semipermeable membrane concentrated water pipe 56. The semipermeable membrane dilution water obtained in the second space 22c of the third-stage semipermeable membrane module 16c is sent through the semipermeable membrane dilution water piping 58 to the second space 22b of the second-stage semipermeable membrane module 16b.

[0084] In the semipermeable membrane treatment device 7 of Figure 4, as in the semipermeable membrane treatment device 6 of Figure 3, hydrogen peroxide decomposition treated water or reverse osmosis membrane concentrated water obtained by reverse osmosis membrane treatment of the hydrogen peroxide decomposition treated water may be supplied to the first space 20a and the second space 22a of the first-stage semipermeable membrane module 16a, and the semipermeable membrane concentrated water may be sequentially supplied to the first space of the next-stage semipermeable membrane module, and semipermeable membrane diluted water may be sequentially supplied to the second space of the next-stage semipermeable membrane module, and the first space 20 of each stage may be pressurized to cause the water contained in the first space 20 to permeate into the second space 22 through the semipermeable membrane 24, thereby concentrating the water. That is, in the semipermeable membrane module 16, the hydrogen peroxide decomposition treated water or reverse osmosis membrane concentrated water is concentrated using the semipermeable membrane 24, and the semipermeable membrane concentrated water is further concentrated using the semipermeable membrane 24 of the next stage.

[0085] In such a semipermeable membrane treatment device or the semipermeable membrane treatment device 7 of FIG. 4, water may be passed through the second spaces in series, or a portion of the semipermeable membrane diluted water obtained in the second spaces 22a, 22b, 22c of the semipermeable membrane modules 16a, 16b, 16c of each stage may be discharged outside the system, or may be sent to a semipermeable membrane diluted water tank and stored therein as necessary, and then discharged outside the system.

[0086] The semipermeable membrane treatment devices in Figures 1, 2, 3, and 4 are examples of device configurations, and the arrangement of the semipermeable membrane modules, the method of supplying feed water, and the like may be changed as appropriate. For example, a multi-stage semipermeable membrane module may be used, and a semipermeable membrane module unit having a plurality of semipermeable membrane modules connected in parallel may be used as the semipermeable membrane module in each stage. An example of a semipermeable membrane treatment device having such a configuration is shown in Figure 5. Figure 5 is an example of device configuration, and the number of stages, number of parallel connections, and arrangement of the semipermeable membrane modules, the method of supplying feed water, and the like may be changed as appropriate.

[0087] The semipermeable membrane treatment device 8 shown in FIG. 5 uses semipermeable membrane modules connected in multiple stages, each having a first space 20 (concentration side) and a second space 22 (permeation side) separated by a semipermeable membrane 24, and in which hydrogen peroxide decomposition treated water or reverse osmosis membrane concentrated water obtained by reverse osmosis membrane treatment of the hydrogen peroxide decomposition treated water is passed through the first space 20 of the first-stage semipermeable membrane module, and the first space 20 is pressurized to cause the water contained in the hydrogen peroxide decomposition treated water or the reverse osmosis membrane concentrated water to permeate through the semipermeable membrane 24, thereby obtaining concentrated water. This concentrated water is further obtained using semipermeable membrane modules in subsequent stages and thereafter, and dilution water is obtained by passing at least a portion of the concentrated water or at least a portion of dilution water obtained from other semipermeable membrane modules through the second space 22 of the semipermeable membrane module of each stage. The semipermeable membrane treatment device 8 includes, for example, a first-stage semipermeable membrane module unit 70a, a second-stage semipermeable membrane module unit 70b, a third-stage semipermeable membrane module unit 70c, and a fourth-stage semipermeable membrane module unit 70d. The first-stage semipermeable membrane module unit 70a, for example, includes four semipermeable membrane modules connected in parallel, the second-stage semipermeable membrane module unit 70b, for example, includes four semipermeable membrane modules connected in parallel, the third-stage semipermeable membrane module unit 70c, for example, includes two semipermeable membrane modules connected in parallel, and the fourth-stage semipermeable membrane module unit 70d, for example, includes two semipermeable membrane modules connected in parallel. Each semipermeable membrane module 16 has a first space 20 and a second space 22 separated by a semipermeable membrane 24. The semipermeable membrane module unit 70 is an apparatus in which hydrogen peroxide decomposition-treated water or reverse osmosis membrane concentrated water is supplied to the first space of the first-stage membrane module, and the concentrated water is sequentially supplied to the first space of the next-stage membrane module to perform a concentration treatment.

[0088] In the semipermeable membrane treatment device 8 of Figure 5, the semipermeable membrane treatment water supply pipe 36 from the membrane supply tank 14 as in Figure 1 or the semipermeable membrane treatment water supply pipe 36 from the reverse osmosis membrane treatment device 18 as in Figure 2 is connected to the first space inlet of the first-stage semipermeable membrane module unit 70a. The first space outlet of each semipermeable membrane module of the first-stage semipermeable membrane module unit 70a is connected to the first space inlet of each semipermeable membrane module of the second-stage semipermeable membrane module unit 70b by a semipermeable membrane concentrated water pipe 72. The first space outlet of each semipermeable membrane module of the second-stage semipermeable membrane module unit 70b is connected to the first space inlet of each semipermeable membrane module of the third-stage semipermeable membrane module unit 70c by a semipermeable membrane concentrated water pipe 74. The first space outlet of each semipermeable membrane module of the third-stage semipermeable membrane module unit 70c is connected to the first space inlet of each semipermeable membrane module of the fourth-stage semipermeable membrane module unit 70d by a semipermeable membrane concentrated water pipe 76. A semipermeable membrane concentrated water pipe 78 is connected to the first space outlet of each semipermeable membrane module in the fourth-stage semipermeable membrane module unit 70d. A semipermeable membrane concentrated water pipe 80 branching from the semipermeable membrane concentrated water pipe 78 is connected to the second space inlet of each semipermeable membrane module in the fourth-stage semipermeable membrane module unit 70d. The second space outlet of each semipermeable membrane module in the fourth-stage semipermeable membrane module unit 70d and the second space inlet of each semipermeable membrane module in the third-stage semipermeable membrane module unit 70c are connected by a semipermeable membrane dilution water pipe 82. The second space outlet of each semipermeable membrane module in the third-stage semipermeable membrane module unit 70c and the second space inlet of each semipermeable membrane module in the second-stage semipermeable membrane module unit 70b are connected by a semipermeable membrane dilution water pipe 84. The second space outlet of each semipermeable membrane module in the second-stage semipermeable membrane module unit 70b and the second space inlet of each semipermeable membrane module in the first-stage semipermeable membrane module unit 70a are connected by a semipermeable membrane dilution water pipe 86. A semipermeable membrane dilution water pipe 88 is connected to the second space outlet of each semipermeable membrane module of the first-stage semipermeable membrane module unit 70a.

[0089] The semipermeable membrane module unit 70 is an apparatus that uses a multistage semipermeable membrane module unit equipped with semipermeable membrane modules 16 having a first space 20 and a second space 22 separated by a semipermeable membrane 24, and supplies hydrogen peroxide decomposition treated water or reverse osmosis membrane concentrated water obtained by reverse osmosis membrane treatment of the hydrogen peroxide decomposition treated water to the first space of each semipermeable membrane module in a first-stage semipermeable membrane module unit, and passes this concentrated water in series to the first spaces of each semipermeable membrane module in the semipermeable membrane module unit of the next stage, supplies at least a portion of the concentrated water from each semipermeable membrane module in the final-stage semipermeable membrane module unit to its own second space, and passes the resulting diluted water in series to the second spaces 22 of each semipermeable membrane module in the semipermeable membrane module unit of the previous stage, and concentrates the water by pressurizing the first spaces 20 of each stage, causing the water contained in the first spaces 20 to permeate into the second spaces 22 via the semipermeable membrane 24. That is, in the semipermeable membrane module unit 70, the hydrogen peroxide decomposition treated water or the reverse osmosis membrane concentrated water is concentrated using the semipermeable membrane 24, and the concentrated water is further concentrated using the semipermeable membrane 24 in the next stage.

[0090] The hydrogen peroxide decomposition treated water or the reverse osmosis membrane concentrated water obtained by reverse osmosis membrane treatment of the hydrogen peroxide decomposition treated water is sent to the first space 20 of each semipermeable membrane module of the first-stage semipermeable membrane module unit 70a through the semipermeable membrane treated water supply piping 36. Meanwhile, the semipermeable membrane dilution water sent via the second space 22 of each semipermeable membrane module of the fourth-stage semipermeable membrane module unit 70d (described later), the second space 22 of each semipermeable membrane module of the third-stage semipermeable membrane module unit 70c, and the second space 22 of each semipermeable membrane module of the second-stage semipermeable membrane module unit 70b is sent to the second space 22 of each semipermeable membrane module of the first-stage semipermeable membrane module unit 70a through the semipermeable membrane dilution water piping 86. In each semipermeable membrane module of the first-stage semipermeable membrane module unit 70a, the first space 20 is pressurized, and the water contained in the first space 20 is permeated into the second space 22 through the semipermeable membrane 24 (concentration process (first stage)), and semipermeable membrane diluted water is obtained in the second space 22 (dilution process (first stage)). The semipermeable membrane concentrated water obtained in the first space 20 of each semipermeable membrane module of the first-stage semipermeable membrane module unit 70a is sent through the semipermeable membrane concentrated water piping 72 to the first space 20 of each semipermeable membrane module of the second-stage semipermeable membrane module unit 70b. The semipermeable membrane diluted water obtained in the second space 22 of each semipermeable membrane module of the first-stage semipermeable membrane module unit 70a is discharged from the second space outlet through the semipermeable membrane diluted water piping 88.

[0091] In each semipermeable membrane module of the second-stage semipermeable membrane module unit 70b, the semipermeable membrane dilution water sent via the second space 22 of each semipermeable membrane module of the fourth-stage semipermeable membrane module unit 70d (described later) and the second space 22 of each semipermeable membrane module of the third-stage semipermeable membrane module unit 70c is sent to the second space 22 of each semipermeable membrane module of the second-stage semipermeable membrane module unit 70b through the semipermeable membrane dilution water piping 84. The first space 20 is pressurized, and the water contained in the first space 20 permeates into the second space 22 through the semipermeable membrane 24 (concentration process (second stage)), and semipermeable membrane dilution water is obtained in the second space 22 (dilution process (second stage)). The semipermeable membrane concentrated water obtained in the first space 20 of each semipermeable membrane module of the second-stage semipermeable membrane module unit 70b is sent through the semipermeable membrane concentrated water piping 74 to the first space 20 of each semipermeable membrane module of the third-stage semipermeable membrane module unit 70c. The semipermeable membrane diluted water obtained in the second space 22 of each semipermeable membrane module of the second-stage semipermeable membrane module unit 70b is sent through the semipermeable membrane diluted water piping 86 to the second space 22 of each semipermeable membrane module of the first-stage semipermeable membrane module unit 70a.

[0092] In each semipermeable membrane module of the third-stage semipermeable membrane module unit 70c, semipermeable membrane dilution water sent via the second space 22 of each semipermeable membrane module of the fourth-stage semipermeable membrane module unit 70d (described later) is sent to the second space 22 of each semipermeable membrane module of the third-stage semipermeable membrane module unit 70c through a semipermeable membrane dilution water piping 82. The first space 20 is pressurized, and the water contained in the first space 20 permeates into the second space 22 through the semipermeable membrane 24 (concentration step (third stage)), and semipermeable membrane dilution water is obtained in the second space 22 (dilution step (third stage)). The semipermeable membrane concentrated water obtained in the first space 20 of each semipermeable membrane module of the third-stage semipermeable membrane module unit 70c is sent through a semipermeable membrane concentrated water piping 76 to the first space 20 of each semipermeable membrane module of the fourth-stage semipermeable membrane module unit 70d. The semipermeable membrane diluted water obtained in the second space 22 of each semipermeable membrane module of the third-stage semipermeable membrane module unit 70c is sent through the semipermeable membrane diluted water piping 84 to the second space 22 of each semipermeable membrane module of the second-stage semipermeable membrane module unit 70b.

[0093] In each semipermeable membrane module of the fourth-stage semipermeable membrane module unit 70d, the semipermeable membrane concentrated water obtained in the first space 20 of each semipermeable membrane module of the fourth-stage semipermeable membrane module unit 70d is sent to the second space 22 through semipermeable membrane concentrated water pipes 78, 80 as described below. The first space 20 is pressurized, and the water contained in the first space 20 permeates into the second space 22 through the semipermeable membrane 24 (concentration step (fourth stage)), and semipermeable membrane diluted water is obtained in the second space 22 (dilution step (fourth stage)) (these are referred to as semipermeable membrane treatment steps). The semipermeable membrane concentrated water obtained in the first space 20 of each semipermeable membrane module of the fourth-stage semipermeable membrane module unit 70d is discharged through the semipermeable membrane concentrated water pipe 78. The semipermeable membrane concentrated water branched from the semipermeable membrane concentrated water pipe 78 is sent through the semipermeable membrane concentrated water pipe 80 to the second space 22 of each semipermeable membrane module of the fourth-stage semipermeable membrane module unit 70d. The semipermeable membrane diluted water obtained in the second space 22 of each semipermeable membrane module of the fourth-stage semipermeable membrane module unit 70d is sent through the semipermeable membrane diluted water piping 82 to the second space 22 of each semipermeable membrane module of the third-stage semipermeable membrane module unit 70c.

[0094] In order to concentrate hydrogen peroxide decomposition-treated water or reverse osmosis membrane concentrated water to a desired concentration in the semipermeable membrane module, it is preferable to arrange multiple semipermeable membrane modules in series. When using a multi-stage semipermeable membrane module, the number of stages of the semipermeable membrane module can be determined depending on the target concentration of the semipermeable membrane concentrated water, etc. For example, if it is desired to obtain semipermeable membrane concentrated water with a higher concentration from hydrogen peroxide decomposition-treated water or reverse osmosis membrane concentrated water with a lower concentration, the number of stages of the semipermeable membrane module unit can be increased.

[0095] When a semipermeable membrane module unit having a plurality of semipermeable membrane modules connected in parallel is used as the membrane module for each stage, the number of semipermeable membrane modules in each semipermeable membrane module unit can be determined based on the flow rate of the hydrogen peroxide decomposition treated water or the reverse osmosis membrane concentrated water, etc.

[0096] A semipermeable membrane concentration tank and a semipermeable membrane dilution tank may be provided in one or more stages of semipermeable membrane modules, or a semipermeable membrane concentration tank and a semipermeable membrane dilution tank may be provided in each stage of semipermeable membrane module.

[0097] This specification includes the following embodiments: (1) A water treatment device comprising: hydrogen peroxide decomposition means for decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and semipermeable membrane treatment means for using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, passing hydrogen peroxide decomposed water treated by the hydrogen peroxide decomposition means through the first space, pressurizing the first space to cause water contained in the hydrogen peroxide decomposition treated water to permeate through the semipermeable membrane, thereby obtaining semipermeable membrane concentrated water, and passing a portion of the hydrogen peroxide decomposition treated water or at least a portion of the semipermeable membrane concentrated water through the second space, thereby obtaining semipermeable membrane diluted water.

[0098] (2) A water treatment device comprising: a hydrogen peroxide decomposition means for decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and semipermeable membrane treatment means using semipermeable membrane modules connected in multiple stages, each having a first space and a second space separated by a semipermeable membrane, for passing hydrogen peroxide decomposed water treated by the hydrogen peroxide decomposition means through the first space of the semipermeable membrane module of a first stage and pressurizing the first space to cause water contained in the hydrogen peroxide decomposition treated water to permeate through the semipermeable membrane, thereby obtaining semipermeable membrane concentrated water, and for further obtaining semipermeable membrane concentrated water using semipermeable membrane modules of subsequent stages and for passing a portion of the hydrogen peroxide decomposition treated water, at least a portion of the semipermeable membrane concentrated water, or at least a portion of semipermeable membrane diluted water obtained from another semipermeable membrane module, through the second space of the semipermeable membrane module of each stage to obtain semipermeable membrane diluted water.

[0099] (3) The water treatment device according to (1) or (2), wherein the ammonium ion concentration in the semipermeable membrane concentrated water is 50,000 mg / L or more.

[0100] (4) The water treatment device according to any one of (1) to (3), which does not include an ammonia stripping treatment means.

[0101] (5) The water treatment device according to any one of (1) to (4), further comprising a pH adjusting means, upstream of the semipermeable membrane treatment means, for adjusting the pH of the ammonia / hydrogen peroxide-containing water to 5 to 8.

[0102] (6) The water treatment device according to any one of (1) to (5), wherein the ammonia / hydrogen peroxide-containing water is wastewater discharged from a semiconductor factory and has a pH of 10 or more.

[0103] (7) A water treatment method comprising: a hydrogen peroxide decomposition step of decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and a semipermeable membrane treatment step of using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, passing hydrogen peroxide decomposed water treated by the hydrogen peroxide decomposition means through the first space, pressurizing the first space to cause water contained in the hydrogen peroxide decomposition treated water to permeate through the semipermeable membrane to obtain semipermeable membrane concentrated water, and passing a portion of the hydrogen peroxide decomposition treated water or at least a portion of the semipermeable membrane concentrated water through the second space to obtain semipermeable membrane diluted water.

[0104] (8) A water treatment method comprising: a hydrogen peroxide decomposition step of decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and a semipermeable membrane treatment step of using semipermeable membrane modules connected in multiple stages, each having a first space and a second space separated by a semipermeable membrane, passing hydrogen peroxide decomposed water treated by the hydrogen peroxide decomposition means through the first space of the semipermeable membrane module of a first stage, pressurizing the first space to cause water contained in the hydrogen peroxide decomposition treated water to permeate through the semipermeable membrane, thereby obtaining semipermeable membrane concentrated water, and further obtaining semipermeable membrane concentrated water using semipermeable membrane modules of subsequent stages, while passing a portion of the hydrogen peroxide decomposition treated water, at least a portion of the semipermeable membrane concentrated water, or at least a portion of semipermeable membrane diluted water obtained from another semipermeable membrane module, through the second space of the semipermeable membrane module of each stage, thereby obtaining semipermeable membrane diluted water.

[0105] (9) The water treatment method according to (7) or (8), wherein the ammonium ion concentration in the semipermeable membrane concentrated water is 50,000 mg / L or more.

[0106] (10) The water treatment method according to any one of (7) to (9), which does not include an ammonia stripping treatment step.

[0107] (11) The water treatment method according to any one of (7) to (10), further comprising a pH adjustment step of adjusting the pH of the ammonia / hydrogen peroxide-containing water to 5 to 8 prior to the semipermeable membrane treatment step.

[0108] (12) The water treatment method according to any one of (7) to (11), wherein the ammonia / hydrogen peroxide-containing water is wastewater discharged from a semiconductor factory and having a pH of 10 or more.

[0109] 1, 3 Water treatment device, 5, 6, 7, 8 Semipermeable membrane treatment device, 10 Water tank to be treated, 12 Hydrogen peroxide decomposition device, 14 Membrane supply water tank, 16 Semipermeable membrane module, 18 Reverse osmosis membrane treatment device, 20 First space, 22 Second space, 24 Semipermeable membrane, 30 Water to be treated piping, 32 Water to be treated supply piping, 34 Hydrogen peroxide decomposition treated water piping, 36, 37 Semipermeable membrane treated water supply piping, 38, 40, 50, 52, 54, 56, 72, 74, 76, 78, 80 Semipermeable membrane concentrated water piping, 42, 43, 58, 60, 62, 82, 84, 86, 88 Semipermeable membrane diluted water piping, 44 pH adjuster addition piping, 46 Hydrogen peroxide decomposition treated water supply piping, 48 Reverse osmosis membrane permeate water piping, 70, 70a, 70b, 70c, 70d Semipermeable membrane module unit.

Claims

1. A water treatment device comprising: hydrogen peroxide decomposition means for decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and semipermeable membrane treatment means for using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, passing hydrogen peroxide decomposed water treated by the hydrogen peroxide decomposition means through the first space, pressurizing the first space to cause water contained in the hydrogen peroxide decomposition treated water to permeate through the semipermeable membrane, thereby obtaining semipermeable membrane concentrated water, and passing a portion of the hydrogen peroxide decomposition treated water or at least a portion of the semipermeable membrane concentrated water through the second space, thereby obtaining semipermeable membrane diluted water.

2. A water treatment device comprising: hydrogen peroxide decomposition means for decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and semipermeable membrane treatment means for using semipermeable membrane modules connected in multiple stages, each having a first space and a second space separated by a semipermeable membrane, in which hydrogen peroxide decomposed water treated in the hydrogen peroxide decomposition means is passed through the first space of the semipermeable membrane module of the first stage, and the first space is pressurized to cause the water contained in the hydrogen peroxide decomposition treated water to pass through the semipermeable membrane, thereby obtaining semipermeable membrane concentrated water, and for further obtaining semipermeable membrane concentrated water from this concentrated water using semipermeable membrane modules of subsequent stages, and for obtaining semipermeable membrane diluted water by passing a portion of the hydrogen peroxide decomposition treated water, at least a portion of the semipermeable membrane concentrated water, or at least a portion of semipermeable membrane diluted water obtained from another semipermeable membrane module, through the second space of the semipermeable membrane module of each stage.

3. A water treatment device according to claim 1 or 2, wherein the ammonium ion concentration in the semipermeable membrane concentrated water is 50,000 mg / L or more.

4. A water treatment device according to any one of claims 1 to 3, characterized in that it does not include an ammonia stripping treatment means.

5. A water treatment device according to any one of claims 1 to 4, further comprising a pH adjusting means, upstream of the semipermeable membrane treatment means, for adjusting the pH of the ammonia / hydrogen peroxide-containing water to 5 to 8.

6. A water treatment device according to any one of claims 1 to 5, wherein the ammonia / hydrogen peroxide-containing water is wastewater discharged from a semiconductor factory and having a pH of 10 or more.

7. A water treatment method comprising: a hydrogen peroxide decomposition step of decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and a semipermeable membrane treatment step of using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, passing hydrogen peroxide decomposed water treated by the hydrogen peroxide decomposition means through the first space, pressurizing the first space to cause water contained in the hydrogen peroxide decomposition treated water to permeate through the semipermeable membrane to obtain semipermeable membrane concentrated water, and passing a portion of the hydrogen peroxide decomposition treated water or at least a portion of the semipermeable membrane concentrated water through the second space to obtain semipermeable membrane diluted water.

8. A water treatment method comprising: a hydrogen peroxide decomposition step of decomposing hydrogen peroxide in ammonia / hydrogen peroxide-containing water containing ammonia and hydrogen peroxide; and a semipermeable membrane treatment step of using semipermeable membrane modules connected in multiple stages, each having a first space and a second space separated by a semipermeable membrane, passing hydrogen peroxide decomposition-treated water treated by the hydrogen peroxide decomposition means through the first space of the semipermeable membrane module of the first stage, pressurizing the first space to cause the water contained in the hydrogen peroxide decomposition-treated water to permeate through the semipermeable membrane, thereby obtaining semipermeable membrane concentrated water, and further obtaining semipermeable membrane concentrated water using semipermeable membrane modules of subsequent stages, while passing a portion of the hydrogen peroxide decomposition-treated water, at least a portion of the semipermeable membrane concentrated water, or at least a portion of semipermeable membrane diluted water obtained from another semipermeable membrane module, through the second space of the semipermeable membrane module of each stage, thereby obtaining semipermeable membrane diluted water.

9. The water treatment method according to claim 7 or 8, wherein the ammonium ion concentration in the semipermeable membrane concentrated water is 50,000 mg / L or more.

10. The water treatment method according to any one of claims 7 to 9, characterized in that it does not include an ammonia stripping treatment step.

11. A water treatment method according to any one of claims 7 to 10, further comprising a pH adjustment step of adjusting the pH of the ammonia / hydrogen peroxide-containing water to 5 to 8 prior to the semipermeable membrane treatment step.

12. The water treatment method according to any one of claims 7 to 11, wherein the ammonia / hydrogen peroxide-containing water is wastewater discharged from a semiconductor factory and having a pH of 10 or higher.

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