JP7637570B2 - Water treatment method and water treatment device - Google Patents

Description

The present invention relates to a water treatment method and water treatment device for recovering valuable materials from ammonia-containing water.

In recent years, methods for recovering valuable materials from wastewater from factories and other facilities include reverse osmosis, which uses a reverse osmosis membrane to recover the permeate and reduce the volume of water, and membrane distillation, which uses a gas-permeable membrane.

As disclosed in Patent Document 1, a method is known in which the water to be treated or its concentrate is passed through a first space and a second space separated by a semipermeable membrane of a semipermeable membrane module, and the first space is pressurized to concentrate the water. This type of concentration method using a semipermeable membrane reduces the difference in concentration (osmotic pressure difference) between the first space and the second space, and can concentrate wastewater to a high concentration with less energy consumption than the general reverse osmosis method.

As shown in Patent Document 2, a method is also known in which ammonia is recovered as a gas from ammonia-containing water using a distillation apparatus. When using a distillation method, a large amount of wastewater is generated after removing the ammonia, which is the recovered product. In addition, the concentration of dissolved solids (TDS), such as inorganic salts, in the wastewater becomes high, making this wastewater unsuitable for reuse. For this reason, the wastewater generated by distillation is discharged as is or after further treatment.

Therefore, there was a need for a method that could recover ammonia from ammonia-containing water, and also recover and reuse valuable materials and water from the wastewater after removing the recovered materials.

JP 2018-069198 A JP 2019-098205 A

The object of the present invention is to provide a water treatment method and water treatment device that can recover ammonia from ammonia-containing water and further recover valuable materials and water from the wastewater after removing the recovered material.

The present invention is a water treatment method for recovering at least one of ammonia and ammonium ions from ammonia-containing water, comprising: a first recovery step of recovering at least one of the ammonia and ammonium ions from the ammonia-containing water using a distillation apparatus as a first recovery product; and a second recovery step of passing distilled water containing dissolved solid components obtained in the distillation apparatus through the first space using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, pressurizing the first space to allow the water contained in the distilled water to permeate through the semipermeable membrane to obtain concentrated water containing the dissolved solid components as a second recovery product, and passing a part of the distilled water or at least a part of the concentrated water through the second space to obtain dilution water . The ammonia-containing water has a sulfate ion concentration of 6000 mg/L or more and an ammonium ion concentration of 2000 mg/L or more . This is a water treatment method.

The present invention is a water treatment method for recovering at least one of ammonia and ammonium ions from ammonia-containing water, comprising: a first recovery step of recovering at least one of the ammonia and ammonium ions from the ammonia-containing water using a distillation apparatus as a first recovery product; and a semipermeable membrane module connected in a plurality of stages, having a first space and a second space separated by a semipermeable membrane, passing distilled water containing dissolved solid components obtained in the distillation apparatus through the first space of the first-stage semipermeable membrane module, pressurizing the first space to allow the water contained in the distilled water to permeate through the semipermeable membrane to obtain concentrated water, and further using the semipermeable membrane module in the next stage or later to obtain concentrated water containing the dissolved solid components as a second recovery product. The water treatment method includes a second recovery step of passing a part of the distilled water or at least a part of the concentrated water or at least a part of the dilution water obtained from another semipermeable membrane module through the second space of the semipermeable membrane module in each stage to obtain diluted water , wherein the ammonia-containing water has a sulfate ion concentration of 6000 mg/L or more and an ammonium ion concentration of 2000 mg/L or more .

In the water treatment method, it is preferable that the method further includes, after the second recovery step, a water recovery step in which at least a portion of the dilution water discharged from the second recovery step is passed through a reverse osmosis membrane to obtain permeate water, and a return step in which concentrated water discharged from the reverse osmosis membrane is returned to the upstream stage of the semipermeable membrane module.

The present invention is a water treatment device that recovers at least one of ammonia and ammonium ions from ammonia-containing water, comprising: a first recovery means for recovering at least one of the ammonia and ammonium ions from the ammonia-containing water using a distillation device as a first recovery product; and a second recovery means for passing distilled water containing dissolved solid components obtained in the distillation device through the first space using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, pressurizing the first space to cause the water contained in the distilled water to permeate through the semipermeable membrane, thereby obtaining concentrated water containing the dissolved solid components as a second recovery product, and passing a part of the distilled water or at least a part of the concentrated water through the second space to obtain dilution water . The ammonia-containing water has a sulfate ion concentration of 6000 mg/L or more and an ammonium ion concentration of 2000 mg/L or more . This is a water treatment device.

The present invention is a water treatment device that recovers at least one of ammonia and ammonium ions from ammonia-containing water, comprising: a first recovery means for recovering at least one of the ammonia and ammonium ions from the ammonia-containing water using a distillation device; and a semipermeable membrane module connected in a plurality of stages, each having a first space and a second space separated by a semipermeable membrane, for passing distilled water containing dissolved solid components obtained in the distillation device through the first space of the first-stage semipermeable membrane module, pressurizing the first space to cause the water contained in the distilled water to permeate through the semipermeable membrane to obtain concentrated water, and further using the semipermeable membrane module in the next stage or later to obtain concentrated water containing the dissolved solid components as a second recovered product. The water treatment device is provided with a second recovery means for passing a portion of the distilled water or at least a portion of the concentrated water or at least a portion of dilution water obtained from another semipermeable membrane module through the second space of the semipermeable membrane module in each stage to obtain dilution water, wherein the ammonia-containing water has a sulfate ion concentration of 6000 mg/L or more and an ammonium ion concentration of 2000 mg/L or more .

It is preferable that the water treatment device further includes, after the second recovery means, a water recovery means for passing at least a portion of the dilution water discharged from the second recovery means through a reverse osmosis membrane to obtain permeated water, and a return means for returning concentrated water discharged from the reverse osmosis membrane to the upstream stage of the semipermeable membrane module.

The present invention provides a water treatment method and water treatment device that can recover ammonia from ammonia-containing water and further recover valuable materials and water from the wastewater after removing the recovered material.

1 is a schematic diagram illustrating an example of a water treatment device according to an embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing another example of a water treatment device according to an embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing another example of a water treatment device according to an embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing another example of a water treatment device according to an embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing another example of a water treatment device according to an embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing another example of a water treatment device according to an embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing another example of a water treatment device according to an embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing another example of a water treatment device according to an embodiment of the present invention.

The following describes an embodiment of the present invention. This embodiment is an example of implementing the present invention, and the present invention is not limited to this embodiment.

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.

The water treatment device 1 shown in FIG. 1 is a device for recovering valuable materials from ammonia-containing water. The water treatment device 1 uses a distillation device 11 and a semipermeable membrane module having a first space (concentration side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12 as a first recovery means for recovering at least one of ammonia and ammonium ions from ammonia-containing water as a first recovery product, and passes distilled water from the distillation device 11 through the first space 14, pressurizes the first space 14 to cause the water contained in the distilled water to permeate the semipermeable membrane 12, thereby obtaining a second recovery product as concentrated water, and passes a part of the distilled water through the second space 16 to obtain dilution water, for example, a membrane module 10 as a second recovery means. The water treatment device 1 may be provided with a distillation water tank for storing distilled water between the distillation device 11 and the membrane module 10.

In the water treatment device 1 of FIG. 1, a pipe 25 is connected to the inlet of the distillation device 11. A pipe 27 is connected to the first recovered product outlet of the distillation device 11. The distilled treated water outlet of the distillation device 11 and the first space inlet of the membrane module 10 are connected by a pipe 24 via a pump 18, and a pipe 26 branching off from the pipe 24 downstream of the pump 18 is connected to the second space inlet of the membrane module 10 via a valve 22. A pipe 28 is connected to the first space outlet of the membrane module 10 via a valve 23, and a pipe 30 is connected to the second space outlet of the membrane module 10.

The pump 18 is, for example, a pressure pump that is driven at a rotational speed according to an input drive frequency, sucks in distilled treated water, and pressurizes and discharges it to the membrane module 10. The pump 18 is equipped with, for example, an inverter 20 that outputs to the pump 18 a drive frequency that corresponds to an input command signal. The valves 22 and 23 are, for example, valves whose opening and closing degree can be adjusted manually or automatically.

The membrane module 10 has a first space 14 and a second space 16 separated by a semipermeable membrane 12, and is an apparatus in which distilled treated water is passed from the first space inlet of the membrane module 10 to the first space 14 and from the second space inlet to the second space 16, and the water is concentrated by pressurizing the first space 14, causing the water contained in the distilled treated water in the first space 14 to permeate through the semipermeable membrane 12 to the second space 16. That is, in the water treatment device 1, the distilled treated water is concentrated using the semipermeable membrane 12. The membrane module 10 is an apparatus in which distilled treated water is supplied to both the first space 14 and the second space 16 of the membrane module 10 to perform a concentration process.

In the water treatment device 1, ammonia-containing water containing ammonia is supplied to the distillation device 11 through the pipe 25. Distillation is performed in the distillation device 11, and at least one of ammonia and ammonium ions is recovered from the ammonia-containing water as a first recovered product (first recovery process). The first recovered product is discharged through the pipe 27.

The distilled water obtained in the distillation apparatus 11 is pressurized and sent from the first space inlet of the membrane module 10 to the first space 14 through the pipe 24 by the pump 18 with the valve 23 open. The distilled water is also sent from the second space inlet of the membrane module 10 to the second space 16 through the pipe 26 branched from the pipe 24 with the valve 22 open. A part of the water contained in the pressurized distilled water permeates from the first space 14 to the second space 16 through the semipermeable membrane 12. At this time, most of the ions contained in the distilled water cannot permeate the semipermeable membrane 12, so the water in the first space 14 that did not permeate the semipermeable membrane 12 is concentrated. On the other hand, in the second space 16, a part of the distilled water passed through the pipe 26 and the permeated water with a low ion concentration that permeated the semipermeable membrane 12 are merged, so a dilution effect is produced. The concentrated water obtained in the first space 14 is discharged as the second recovered product from the first space outlet through the pipe 28, and the diluted water obtained in the second space 16 is discharged from the second space outlet through the pipe 30. Here, in the membrane module 10, the first space 14 is pressurized and the water contained in the distilled treated water in the first space 14 is permeated through the semipermeable membrane 12 into the second space 16, and concentrated water (second recovered product) is obtained in the first space 14 (concentration process), and diluted water is obtained in the second space 16 (dilution process) (the above is the second recovery process).

Here, the pipes 24, 26, pump 18, etc. function as a supply means for supplying distilled treated water to both the first space 14 and the second space 16 of the membrane module 10.

The diluted water obtained in the second space 16 may be discharged to the outside of the system through the pipe 30, or may be sent to a dilution water tank and stored as necessary, and then discharged to the outside of the system or reused. At least a portion of the diluted water may be sent to a distillation treatment water tank and mixed with the distillation treatment water in the distillation treatment water tank. At least a portion of the diluted water may be further processed, for example, by reverse osmosis membrane processing as described below.

In this manner, at least one of ammonia and ammonium ions is recovered as a first recovered product from the ammonia-containing water that contains ammonia, which is the target of treatment, and further, concentrated water in which the ions are concentrated is recovered as a second recovered product, and dilution water is obtained, and the volume of the ammonia-containing water is reduced. In addition, the first recovered product, the second recovered product, and the dilution water can be reused.

By passing the distilled water through the first space 14 and the second space 16 of the membrane module 10, the osmotic pressure difference between the first space 14 side and the second space 16 side of the semipermeable membrane 12 is reduced, and the high concentration of ions in the distilled water can be concentrated with less energy consumption. In other words, the distilled water containing ions at high concentrations can be concentrated at low cost, and the amount of waste liquid with high ion concentrations can be reduced.

The following method, for example, can be used to adjust the supply flow rate of the distilled water, the permeate flow rate, and the concentrate flow rate to the membrane module 10.

The pump 18 is provided with an inverter 20 that controls the drive frequency, and the supply flow rate of the distilled treated water to the membrane module 10 is adjusted. Although it is preferable to provide the inverter 20 to the pump 18, it is not necessary to do so. The distilled treated water is supplied to both the first space 14 side and the second space 16 side, a valve 22 is provided before the inlet of the second space 16, and a valve 23 is provided at the outlet of the first space 14. The opening of the valves 22 and 23 is manually or automatically adjusted to adjust the ratio of the supply water flow rate to the first space 14 side and the supply water flow rate to the second space 16 side.

If the permeate flow rate or the concentrated water flow rate is insufficient, the frequency of the inverter 20 of the pump 18 can be increased to increase the supply of distilled water.

A valve 23 whose opening degree can be adjusted is provided at the outlet of the first space 14 of the pipe 28, and the concentrated water flow rate and the pressure at the inlet of the first space 14 and the outlet of the first space 14 can be adjusted by the opening degree of the valve 23.

These operations allow adjustments to the pressure and various flow rates on the first space 14 side.

The distilled water may be supplied to the first space 14 and the second space 16 by separate pumps. When the distilled water is supplied by separate pumps, each pump may be provided with an inverter that controls the drive frequency.

By passing distilled water of the same or similar concentration through both the first space 14 and the second space 16, the osmotic pressure generated by the semipermeable membrane 12 can be reduced, and the required pressure can be reduced. As a result, it is possible to concentrate distilled water to a concentration that could not be achieved using conventional reverse osmosis membrane methods.

In this way, ammonia can be recovered from the ammonia-containing water, and valuable materials and water can be further recovered from the distilled water after the recovered material has been removed. While recovering ammonia from the ammonia-containing water using a distillation method, the distilled water can be concentrated to a high concentration using a semipermeable membrane module, thereby increasing the amount of recovered material, reducing the amount of discharged water, and improving the water recovery rate.

An outline of another example of a water treatment device according to an embodiment of the present invention is shown in Figure 2, and its configuration will be described.

The water treatment device 2 shown in FIG. 2 uses a distillation device 11 and a semipermeable membrane module having a first space (concentration side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12 as a first recovery means for recovering at least one of ammonia and ammonium ions from ammonia-containing water as a first recovery product, and passes distilled water from the distillation device 11 through the first space 14, pressurizes the first space 14 to cause the water contained in the distilled water to permeate the semipermeable membrane 12, thereby obtaining a second recovery product as concentrated water, and passes at least a portion of the concentrated water through the second space 16 to obtain dilution water, for example, a membrane module 10 as a second recovery means. The water treatment device 2 may also include a distillation water tank for storing distilled water between the distillation device 11 and the membrane module 10.

In the water treatment device 2 of FIG. 2, a pipe 25 is connected to the inlet of the distillation device 11. A pipe 27 is connected to the first recovered product outlet of the distillation device 11. The distilled treated water outlet of the distillation device 11 and the first space inlet of the membrane module 10 are connected by a pipe 24 via a pump 18. A pipe 28 is connected to the first space outlet of the membrane module 10 via a valve 23. A pipe 34 branched off from the pipe 28 upstream of the valve 23 is connected to the second space inlet of the membrane module 10 via a valve 32. A pipe 36 is connected to the second space outlet of the membrane module 10.

The pump 18 is, for example, a pressure pump that is driven at a rotational speed according to an input drive frequency, sucks in distilled treated water, and pressurizes and discharges it to the membrane module 10. The pump 18 is equipped with, for example, an inverter 20 that outputs to the pump 18 a drive frequency that corresponds to an input command signal. The valves 23 and 32 are, for example, valves whose opening and closing degree can be adjusted manually or automatically.

The membrane module 10 has a first space 14 and a second space 16 separated by a semipermeable membrane 12, and passes distilled water through the first space inlet of the membrane module 10 into the first space 14, and passes at least a portion of the concentrated water discharged from the first space outlet of the first space 14 of the membrane module 10 into the second space 16 from the second space inlet of the membrane module 10, and pressurizes the first space 14, thereby concentrating the water by permeating the water contained in the distilled water in the first space 14 into the second space 16 through the semipermeable membrane 12. That is, in the water treatment device 2, the distilled water is concentrated using the semipermeable membrane 12. The membrane module 10 is a device that supplies distilled water to the first space 14 of the membrane module 10, and supplies at least a portion of the concentrated water obtained from the outlet of the first space 14 to the second space 16 of the membrane module 10 to perform a concentration process.

In the water treatment device 2, ammonia-containing water containing ammonia is supplied to the distillation device 11 through the pipe 25. Distillation is performed in the distillation device 11, and at least one of ammonia and ammonium ions is recovered from the ammonia-containing water as a first recovered product (first recovery process). The first recovered product is discharged through the pipe 27.

The distilled water obtained in the distillation apparatus 11 is pressurized and sent from the first space inlet of the membrane module 10 to the first space 14 through the pipe 24 by the pump 18 with the valve 23 open, and is passed through. A part of the water contained in the pressurized distilled water permeates from the first space 14 to the second space 16 through the semipermeable membrane 12. At this time, most of the ions cannot permeate the semipermeable membrane 12, so the water in the first space 14 that did not permeate the semipermeable membrane 12 is concentrated. On the other hand, in the second space 16, a part of the concentrated water passed through the pipe 34 and the permeated water with a low ion concentration that permeated the semipermeable membrane 12 are merged, so a dilution effect works. The concentrated water obtained in the first space 14 is discharged as a second recovery product through the pipe 28 from the first space outlet, and at least a part of the concentrated water is sent from the second space inlet of the membrane module 10 to the second space 16 through the pipe 34 branched from the pipe 28 with the valve 32 open, and is passed through. The diluted water obtained in the second space 16 is discharged from the second space outlet through the pipe 36. Here, in the membrane module 10, the first space 14 is pressurized, and the water contained in the distilled water in the first space 14 is permeated through the semipermeable membrane 12 into the second space 16, and concentrated water (second recovered product) is obtained in the first space 14 (concentration process), and diluted water is obtained in the second space 16 (dilution process) (the above is the second recovery process).

Here, the pipes 24, 28, 34, the pump 18, etc. function as a supply means for supplying the distilled treated water to the first space 14 of the membrane module 10 and supplying at least a portion of the concentrated water obtained from the outlet of the first space 14 to the second space 16 of the membrane module 10.

The diluted water obtained in the second space 16 may be discharged to the outside of the system through the pipe 36, or, if necessary, may be sent to a dilution water tank and stored there, and then discharged to the outside of the system or reused. At least a portion of the diluted water may be sent to a distillation treatment water tank and mixed with the distillation treatment water in the distillation treatment water tank. At least a portion of the diluted water may be further processed, for example, by reverse osmosis membrane processing as described below.

In this manner, at least one of ammonia and ammonium ions is recovered as a first recovered product from the ammonia-containing water that contains ammonia, which is the target of treatment, and further, concentrated water in which the ions are concentrated is recovered as a second recovered product, and dilution water is obtained, and the volume of the ammonia-containing water is reduced. In addition, the first recovered product, the second recovered product, and the dilution water can be reused.

By passing the distilled water through the first space 14 of the membrane module 10 and passing at least a portion of the concentrated water obtained in the first space 14 through the second space 16, the osmotic pressure difference between the first space 14 side and the second space 16 side of the semipermeable membrane 12 is reduced, and high concentrations of ions in the distilled water can be concentrated with less energy consumption. In other words, distilled water containing ions at high concentrations can be concentrated at low cost, and the amount of waste liquid with high ion concentrations can be reduced.

The following method, for example, can be used to adjust the supply flow rate of the distilled water, the permeate flow rate, and the concentrate flow rate to the membrane module 10.

The pump 18 is provided with an inverter 20 that controls the drive frequency, and the flow rate of the distilled treated water supplied to the membrane module 10 is adjusted. Although it is preferable to provide the inverter 20 to the pump 18, it is not necessary to do so. The distilled treated water is supplied to the first space 14 side, a valve 23 is provided at the outlet of the first space 14, and a valve 32 is provided before the inlet of the second space 16. The opening of the valves 23 and 32 is manually or automatically adjusted to adjust the ratio of the flow rate of the water supplied to the first space 14 side to the flow rate of the water supplied to the second space 16 side.

If the permeate flow rate or the concentrated water flow rate is insufficient, the frequency of the inverter 20 of the pump 18 can be increased to increase the supply of distilled water.

A valve 23 whose opening degree can be adjusted is provided at the outlet of the first space 14 of the pipe 28, and the concentrated water flow rate and the pressure at the inlet of the first space 14 and the outlet of the first space 14 can be adjusted by the opening degree of the valve 23.

These operations allow adjustments to the pressure and various flow rates on the first space 14 side.

A concentrated water tank for storing concentrated water may be provided midway along the piping 34, and the distilled water may be supplied to the first space 14 and the concentrated water may be supplied to the second space 16 by separate pumps. When the distilled water and concentrated water are supplied by separate pumps, each pump may be provided with an inverter that controls the drive frequency.

By passing distilled water through the first space 14 and concentrated water of a similar concentration through the second space 16, the osmotic pressure generated by the semipermeable membrane 12 can be reduced, reducing the required pressure. As a result, it is possible to concentrate distilled water to a concentration that could not be achieved using conventional reverse osmosis membrane methods.

In the water treatment method and water treatment device according to this embodiment, the ammonia-containing water before being sent to the distillation device 11 (after pretreatment and before being sent to the distillation device 11, if a pretreatment means is provided) has, for example, a sulfate ion concentration of 6000 mg/L or more and an ammonium ion concentration of 2000 mg/L or more. The sulfate ion concentration of the ammonia-containing water is preferably 20000 mg/L or more, and more preferably in the range of 20000 to 250000 mg/L. The ammonium ion concentration of the ammonia-containing water is preferably 2000 mg/L or more, and more preferably in the range of 2000 to 100000 mg/L.

The inlet pressure of the first space 14 is preferably in the range of 7 MPa or less, the inlet pressure of the second space 16 is preferably lower than the inlet pressure of the first space 14, and the inlet pressure of the second space 16 is more preferably 50% or less of the inlet pressure of the first space 14. This reduces the risk of damage to the semipermeable membrane due to pressure.

It is preferable to make the flow rate on the first space 14 side greater than the flow rate on the second space 16 side. If the flow rate on the first space 14 side is equal to or lower than the flow rate on the second space 16 side, the permeation flux may become too high. For example, the pump 18, inverter 20, valve 22, valve 23, valve 32, etc. function as flow rate adjustment means that make the flow rate in the first space greater than the flow rate in the second space.

If the permeation flux is too large, the concentration difference will be large, which may cause problems such as a high risk of fouling and excessive pressure. If the permeation flux is too small, the concentration efficiency may be poor. From these points of view, the permeation flux of the membrane module 10 is preferably in the range of 0.005 m/d to 0.05 m/d, and more preferably in the range of 0.015 m/d to 0.04 m/d. The permeation flux is defined as the permeation flow rate per unit time and unit membrane area. For example, the pump 18, inverter 20, valve 22, valve 23, valve 32, etc. function as a permeation flux adjustment means for controlling the permeation flux within the above range.

Note that the installation positions and number of valves are merely examples, and the number may be greater than those shown in Figures 1 and 2, and valves may be installed in at least one of the other pipes. In addition, a flowmeter as a flow measurement means for measuring the flow rate, or a pressure gauge as a pressure measurement means for measuring the pressure, may be installed in at least one of the pipes.

In the water treatment method and water treatment device according to this embodiment, a multi-stage semipermeable membrane module may be used. Examples of water treatment devices with such a configuration are shown in Figures 3, 4, and 5. The water treatment devices shown in Figures 3, 4, and 5 have a structure in which semipermeable membrane modules are combined in series in three stages.

The water treatment device 3 shown in FIG. 3 uses a distillation device 11 and a semipermeable membrane module connected in multiple stages having a first space (concentration side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12 as a first recovery means for recovering at least one of ammonia and ammonium ions from ammonia-containing water as a first recovery product, and passes the distilled water from the distillation device 11 through the first space 14 of the first-stage semipermeable membrane module, pressurizes the first space 14 to permeate the water contained in the distilled water through the semipermeable membrane 12 to obtain concentrated water, and further uses the concentrated water as a second recovery product using the semipermeable membrane module of the next stage or later, and passes a part of the distilled water or a part of the concentrated water through the second space 16 of the semipermeable membrane module of each stage to obtain dilution water, for example, a first-stage membrane module 10a, a second-stage membrane module 10b, and a third-stage membrane module 10c as a second recovery means. Each membrane module has a first space 14 and a second space 16 separated by a semipermeable membrane 12. The water treatment device 3 may include a dilution water tank 60a for storing dilution water from the first-stage membrane module 10a, a dilution water tank 60b for storing dilution water from the second-stage membrane module 10b, and a dilution water tank 60c for storing dilution water from the third-stage membrane module 10c. The membrane module 10 is a device that supplies distilled water to the first and second spaces of the first-stage membrane module, and sequentially supplies the concentrated water to the first and second spaces of the next-stage membrane module to perform concentration treatment. The water treatment device 3 may include a distillation water tank for storing distillation water between the distillation device 11 and the membrane module 10.

In the water treatment device 3 of FIG. 3, a pipe 25 is connected to the inlet of the distillation device 11. A pipe 27 is connected to the first recovered product outlet of the distillation device 11. The distilled treated water outlet of the distillation device 11 and the first space inlet of the first-stage membrane module 10a are connected by a pipe 40 via a pump 18. A pipe 42 branched from the downstream side of the pump 18 of the pipe 40 is connected to the second space inlet of the membrane module 10a via a valve 22a. The second space outlet of the first-stage membrane module 10a and the inlet of the dilution water tank 60a are connected by a pipe 46. The first space outlet of the first-stage membrane module 10a and the first space inlet of the second-stage membrane module 10b are connected by a pipe 44. A pipe 48 branched from the pipe 44 is connected to the second space inlet of the second-stage membrane module 10b via a valve 22b. The second space outlet of the second-stage membrane module 10b and the inlet of the dilution water tank 60b are connected by a pipe 52. The first space outlet of the second-stage membrane module 10b and the first space inlet of the third-stage membrane module 10c are connected by a pipe 50. A pipe 54 branching from the pipe 50 is connected to the second space inlet of the third-stage membrane module 10c via a valve 22c. The second space outlet of the third-stage membrane module 10c and the inlet of the dilution water tank 60c are connected by a pipe 58. A pipe 56 is connected to the first space outlet of the third-stage membrane module 10c via a valve 23.

The membrane module 10 is a device that uses a multi-stage membrane module having a first space 14 and a second space 16 separated by a semipermeable membrane 12, supplies distilled water to the first space and the second space of the first stage membrane module, sequentially supplies the concentrated water to the first space and the second space of the next stage membrane module, and concentrates the water by pressurizing the first space 14 of each stage to permeate the water contained in the first space 14 through the semipermeable membrane 12 into the second space 16. That is, in the membrane module 10, the distilled water is concentrated using the semipermeable membrane 12, and the concentrated water is further concentrated using the semipermeable membrane 12 of the next stage.

In the water treatment device 3, ammonia-containing water containing ammonia is supplied to the distillation device 11 through the pipe 25. Distillation is performed in the distillation device 11, and at least one of ammonia and ammonium ions is recovered from the ammonia-containing water as a first recovered product (first recovery process). The first recovered product is discharged through the pipe 27.

The distilled water obtained in the distillation apparatus 11 is pumped to the first space 14a of the first-stage membrane module 10a through the pipe 40 by the pump 18 with the valve 23 open, and the distilled water branched off from the pipe 40 is pumped to the second space 16a of the first-stage membrane module 10a through the pipe 42 with the valve 22a open. In the first-stage membrane module 10a, the first space 14a is pressurized and the water contained in the first space 14a is permeated through the semipermeable membrane 12a into the second space 16a (concentration process (first stage)), and dilution water is obtained in the second space 16a (dilution process (first stage)). The dilution water obtained in the second space 16a of the first-stage membrane module 10a is stored in the dilution water tank 60a as necessary through the pipe 46, and then discharged outside the system.

The concentrated water obtained in the first space 14a of the first-stage membrane module 10a is sent to the first space 14b of the second-stage membrane module 10b through the pipe 44, and the concentrated water branched off from the pipe 44 is sent to the second space 16b of the second-stage membrane module 10b through the pipe 48 with the valve 22b open. In the second-stage membrane module 10b, the first space 14b is pressurized and the water contained in the first space 14b is permeated through the semipermeable membrane 12b into the second space 16b (concentration process (second stage)), and dilution water is obtained in the second space 16b (dilution process (second stage)). The dilution water obtained in the second space 16b of the second-stage membrane module 10b is stored in the dilution water tank 60b as necessary through the pipe 52, and then discharged outside the system.

The concentrated water obtained in the first space 14b of the second-stage membrane module 10b is sent to the first space 14c of the third-stage membrane module 10c through the pipe 50, and the concentrated water branched off from the pipe 50 is sent to the second space 16c of the third-stage membrane module 10c through the pipe 54 with the valve 22c open. In the third-stage membrane module 10c, the first space 14c is pressurized and the water contained in the first space 14c is permeated through the semipermeable membrane 12c into the second space 16c (concentration process (third stage)), and dilution water is obtained in the second space 16c (dilution process (third stage)) (the above is the second recovery process). The dilution water obtained in the second space 16c of the third-stage membrane module 10c is stored in the dilution water tank 60c as necessary through the pipe 58, and then discharged outside the system. The concentrated water obtained in the first space 14c of the third-stage membrane module 10c is discharged as the second recovery product through the pipe 56.

Here, the pump 18, piping 40, 42, 44, 48, 50, 54, etc. function as a supply means for supplying distilled treated water or concentrated water to the first spaces 14a, 14b, 14c and second spaces 16a, 16b, 16c of the membrane modules 10a, 10b, 10c of each stage.

The dilution water obtained in the second spaces 16a, 16b, and 16c of the membrane modules 10a, 10b, and 10c of each stage may be discharged outside the system, or may be sent to and stored in the dilution water tanks 60a, 60b, and 60c as necessary, and then discharged outside the system or reused. At least a portion of the dilution water may be sent to the distillation treatment water tank and mixed with the distillation treatment water in the distillation treatment water tank. At least a portion of the dilution water may be further processed, for example, by reverse osmosis membrane processing as described below.

In this manner, at least one of ammonia and ammonium ions is recovered as a first recovered product from the ammonia-containing water to be treated, and further, concentrated water in which the ions are concentrated (final stage concentrated water) is recovered as a second recovered product, and dilution water (dilution water of each stage) is obtained, and the volume of the ammonia-containing water is reduced. In addition, the first recovered product, the second recovered product, and the dilution water can be reused.

The water treatment device 4 shown in FIG. 4 uses a distillation device 11 and a semipermeable membrane module connected in multiple stages having a first space (concentration side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12 as a first recovery means for recovering at least one of ammonia and ammonium ions from ammonia-containing water as a first recovery product, and passes the distilled water from the distillation device 11 through the first space 14 of the first-stage semipermeable membrane module, pressurizes the first space 14 to permeate the water contained in the distilled water through the semipermeable membrane 12 to obtain concentrated water, and further uses the concentrated water as concentrated water using the semipermeable membrane module of the next stage or later to obtain a second recovery product, and also has, for example, a first-stage membrane module 10a, a second-stage membrane module 10b, and a third-stage membrane module 10c as a second recovery means for passing at least a portion of the concentrated water through the second space 16 of the semipermeable membrane module of each stage to obtain dilution water. Each membrane module has a first space 14 and a second space 16 separated by a semipermeable membrane 12. The water treatment device 4 may include a dilution water tank 62a for storing dilution water from the first-stage membrane module 10a, a dilution water tank 62b for storing dilution water from the second-stage membrane module 10b, and a dilution water tank 62c for storing dilution water from the third-stage membrane module 10c. The membrane module 10 is a device that supplies distilled water to the first space of the first-stage membrane module, and sequentially supplies the concentrated water to the first space of the next-stage membrane module and its own second space to perform concentration treatment. The water treatment device 4 may include a distillation water tank for storing distillation water between the distillation device 11 and the membrane module 10.

In the water treatment device 4 of FIG. 4, a pipe 25 is connected to the inlet of the distillation device 11. A pipe 27 is connected to the first recovered product outlet of the distillation device 11. The distilled treated water outlet of the distillation device 11 and the first space inlet of the first-stage membrane module 10a are connected by a pipe 40 via a pump 18. The first space outlet of the first-stage membrane module 10a and the first space inlet of the second-stage membrane module 10b are connected by a pipe 44. A pipe 64 branched from the pipe 44 is connected to the second space inlet of the membrane module 10a via a valve 32a. The second space outlet of the first-stage membrane module 10a and the inlet of the dilution water tank 62a are connected by a pipe 66. The first space outlet of the second-stage membrane module 10b and the first space inlet of the third-stage membrane module 10c are connected by a pipe 50. A pipe 68 branched from the pipe 50 is connected to the second space inlet of the membrane module 10b via a valve 32b. The second space outlet of the second-stage membrane module 10b and the inlet of the dilution water tank 62b are connected by a pipe 70. The first space outlet of the third-stage membrane module 10c is connected to a pipe 56 via a valve 23. A pipe 72 branching off from the pipe 56 upstream of the valve 23 is connected to the second space inlet of the membrane module 10c via a valve 32c. The second space outlet of the third-stage membrane module 10c and the inlet of the dilution water tank 62c are connected by a pipe 74.

The membrane module 10 is a device that uses a multi-stage membrane module having a first space 14 and a second space 16 separated by a semipermeable membrane 12, supplies distilled water to the first space of the first stage membrane module, and sequentially supplies the concentrated water to the first space of the next stage membrane module and its own second space, and by pressurizing the first space 14 of each stage, the water contained in the first space 14 is permeated through the semipermeable membrane 12 into the second space 16, concentrating the water. That is, in the membrane module 10, the distilled water is concentrated using the semipermeable membrane 12, and the concentrated water is further concentrated using the semipermeable membrane 12 of the next stage.

In the water treatment device 4, ammonia-containing water containing ammonia is supplied to the distillation device 11 through the pipe 25. Distillation is performed in the distillation device 11, and at least one of ammonia and ammonium ions is recovered from the ammonia-containing water as a first recovered product (first recovery process). The first recovered product is discharged through the pipe 27.

The distilled water obtained in the distillation apparatus 11 is sent to the first space 14a of the first-stage membrane module 10a through the pipe 40 by the pump 18 with the valve 23 open. In the first-stage membrane module 10a, the first space 14a is pressurized and the water contained in the first space 14a is permeated through the semipermeable membrane 12a into the second space 16a (concentration process (first stage)), and dilution water is obtained in the second space 16a (dilution process (first stage)). The concentrated water obtained in the first space 14a of the first-stage membrane module 10a is sent to the first space 14b of the second-stage membrane module 10b through the pipe 44, and the concentrated water branched off from the pipe 44 is sent to the second space 16a of the first-stage membrane module 10a through the pipe 64 with the valve 32a open. The dilution water obtained in the second space 16a of the first-stage membrane module 10a is stored in the dilution water tank 62a as necessary through piping 66, and then discharged outside the system.

In the second-stage membrane module 10b, the first space 14b is pressurized, and the water contained in the first space 14b is permeated through the semipermeable membrane 12b into the second space 16b (concentration process (second stage)), and dilution water is obtained in the second space 16b (dilution process (second stage)). The concentrated water obtained in the first space 14b of the second-stage membrane module 10b is sent to the first space 14c of the third-stage membrane module 10c through the pipe 50, and the concentrated water branched off from the pipe 50 is sent to the second space 16b of the second-stage membrane module 10b through the pipe 68 with the valve 32b open. The dilution water obtained in the second space 16b of the second-stage membrane module 10b is stored in the dilution water tank 62b as necessary through the pipe 70, and then discharged outside the system.

In the third-stage membrane module 10c, the first space 14c is pressurized, and the water contained in the first space 14c is permeated through the semipermeable membrane 12c into the second space 16c (concentration process (third stage)), and dilution water is obtained in the second space 16c (dilution process (third stage)) (above, the second recovery process). The concentrated water obtained in the first space 14c of the third-stage membrane module 10c is discharged as the second recovery product through the pipe 56. The concentrated water branched off from the pipe 56 is sent to the second space 16c of the third-stage membrane module 10c through the pipe 72 with the valve 32c open. The dilution water obtained in the second space 16c of the third-stage membrane module 10c is stored in the dilution water tank 62c as necessary through the pipe 74, and then discharged outside the system.

Here, the pump 18, piping 40, 44, 64, 50, 68, 56, 72, etc. function as a supply means for supplying distilled treated water or concentrated water to the first spaces 14a, 14b, 14c and second spaces 16a, 16b, 16c of the membrane modules 10a, 10b, 10c of each stage.

The dilution water obtained in the second spaces 16a, 16b, and 16c of the membrane modules 10a, 10b, and 10c of each stage may be discharged outside the system, or may be sent to and stored in the dilution water tanks 62a, 62b, and 62c as necessary, and then discharged outside the system or reused. At least a portion of the dilution water may be sent to the distillation treatment water tank and mixed with the distillation treatment water in the distillation treatment water tank. At least a portion of the dilution water may be further processed, for example, by reverse osmosis membrane processing as described below.

In this manner, at least one of ammonia and ammonium ions is recovered as a first recovered product from the ammonia-containing water to be treated, and further, concentrated water in which the ions are concentrated (final stage concentrated water) is recovered as a second recovered product, and dilution water (dilution water of each stage) is obtained, and the volume of the ammonia-containing water is reduced. In addition, the first recovered product, the second recovered product, and the dilution water can be reused.

When using a multi-stage membrane module, water may be passed through the second space in series. An example of a water treatment device with such a configuration is shown in Figure 5.

The water treatment device 5 shown in FIG. 5 uses a distillation device 11 and a semipermeable membrane module connected in multiple stages having a first space (concentration side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12 as a first recovery means for recovering at least one of ammonia and ammonium ions from ammonia-containing water as a first recovery product, and passes the distilled water from the distillation device 11 through the first space 14 of the first-stage semipermeable membrane module, pressurizes the first space 14 to cause the water contained in the distilled water to permeate the semipermeable membrane 12 to obtain concentrated water, and further obtains concentrated water using the semipermeable membrane module of the next stage or later, and passes at least a portion of the concentrated water or at least a portion of the dilution water obtained from another semipermeable membrane module through the second space 16 of the semipermeable membrane module of each stage to obtain dilution water, for example, a first-stage membrane module 10a, a second-stage membrane module 10b, and a third-stage membrane module 10c as second recovery means. Each membrane module has a first space 14 and a second space 16 separated by a semipermeable membrane 12. The membrane module 10 is a device that supplies distilled water to the first space of the first membrane module, and then sequentially supplies the concentrated water to the first space of the next membrane module to perform concentration processing. The water treatment device 5 may include a distilled water tank between the distillation device 11 and the membrane module 10 to store the distilled water.

In the water treatment device 5 of FIG. 5, a pipe 25 is connected to the inlet of the distillation device 11. A pipe 27 is connected to the first recovered product outlet of the distillation device 11. The distilled treated water outlet of the distillation device 11 and the first space inlet of the first-stage membrane module 10a are connected by a pipe 40 via a pump 18. The first space outlet of the first-stage membrane module 10a and the first space inlet of the second-stage membrane module 10b are connected by a pipe 44. The first space outlet of the second-stage membrane module 10b and the first space inlet of the third-stage membrane module 10c are connected by a pipe 50. A pipe 56 is connected to the first space outlet of the third-stage membrane module 10c via a valve 23. A pipe 76 branched from the pipe 56 upstream of the valve 23 is connected to the second space inlet of the membrane module 10c via a valve 32. The second space outlet of the third-stage membrane module 10c and the second space inlet of the second-stage membrane module 10b are connected by a pipe 78. The second space outlet of the second stage membrane module 10b and the second space inlet of the first stage membrane module 10a are connected by piping 80. A piping 82 is connected to the second space outlet of the first stage membrane module 10a.

The membrane module 10 uses a multi-stage membrane module having a first space 14 and a second space 16 separated by a semipermeable membrane 12, supplies distilled water to the first space of the first membrane module, passes the concentrated water in series to the first space of the membrane module of the next stage, supplies at least a portion of the concentrated water of the membrane module of the final stage to its own second space, passes the resulting diluted water in series to the second space of the membrane module of the previous stage, and pressurizes the first space 14 of each stage to permeate the water contained in the first space 14 through the semipermeable membrane 12 to the second space 16, concentrating the water. That is, in the membrane module 10, the distilled water is concentrated using the semipermeable membrane 12, and the concentrated water is further concentrated using the semipermeable membrane 12 of the next stage.

In the water treatment device 5, ammonia-containing water containing ammonia is supplied to the distillation device 11 through the pipe 25. Distillation is performed in the distillation device 11, and at least one of ammonia and ammonium ions is recovered from the ammonia-containing water as a first recovered product (first recovery process). The first recovered product is discharged through the pipe 27.

The distilled water obtained in the distillation apparatus 11 is pumped to the first space 14a of the first-stage membrane module 10a through the pipe 40 by the pump 18 with the valve 23 open. Meanwhile, the dilution water sent through the second space 16c of the third-stage membrane module 10c and the second space 16b of the second-stage membrane module 10b described later is sent to the second space 16a of the first-stage membrane module 10a through the pipe 80. In the first-stage membrane module 10a, the first space 14a is pressurized and the water contained in the first space 14a is permeated through the semipermeable membrane 12a into the second space 16a (concentration process (first stage)), and dilution water is obtained in the second space 16a (dilution process (first stage)). The concentrated water obtained in the first space 14a of the first-stage membrane module 10a is sent to the first space 14b of the second-stage membrane module 10b through the pipe 44. The dilution water obtained in the second space 16a of the first-stage membrane module 10a is discharged outside the system through piping 82.

In the second-stage membrane module 10b, the dilution water sent via the second space 16c of the third-stage membrane module 10c described later is sent to the second space 16b of the second-stage membrane module 10b through the pipe 78. The first space 14b is pressurized, and the water contained in the first space 14b is permeated into the second space 16b through the semipermeable membrane 12b (concentration process (second stage)), and dilution water is obtained in the second space 16b (dilution process (second stage)). The concentrated water obtained in the first space 14b of the second-stage membrane module 10b is sent to the first space 14c of the third-stage membrane module 10c through the pipe 50. The dilution water obtained in the second space 16b of the second-stage membrane module 10b is sent to the second space 16a of the first-stage membrane module 10a through the pipe 80.

In the third-stage membrane module 10c, the concentrated water obtained in the first space 14c of the third-stage membrane module 10c is sent to the second space 16c through the pipes 56 and 76 as follows. The first space 14c is pressurized, and the water contained in the first space 14c is permeated into the second space 16c through the semipermeable membrane 12c (concentration process (third stage)), and dilution water is obtained in the second space 16c (dilution process (third stage)) (above, the second recovery process). The concentrated water obtained in the first space 14c of the third-stage membrane module 10c is discharged as the second recovery product through the pipe 56. The concentrated water branched from the pipe 56 is sent to the second space 16c of the third-stage membrane module 10c through the pipe 76 with the valve 32 open. The dilution water obtained in the second space 16c of the third-stage membrane module 10c is sent to the second space 16b of the second-stage membrane module 10b through the pipe 78.

Here, the pump 18, piping 40, 44, 50, 56, 76, 78, 80, etc. function as a supply means for supplying distilled treated water, concentrated water, or diluted water to the first spaces 14a, 14b, 14c and second spaces 16a, 16b, 16c of the membrane modules 10a, 10b, 10c of each stage.

The dilution water obtained in the second space 16a of the membrane module 10a may be discharged outside the system, or, if necessary, may be sent to a dilution water tank and stored there, and then discharged outside the system or reused. At least a portion of the dilution water may be sent to a distillation treatment water tank and mixed with the distillation treatment water in the distillation treatment water tank. At least a portion of the dilution water may be further processed, for example, by reverse osmosis membrane processing as described below.

In this manner, at least one of ammonia and ammonium ions is recovered as a first recovered product from the ammonia-containing water to be treated, and further, concentrated water (final stage concentrated water) in which the ions are concentrated is recovered as a second recovered product, and dilution water (first stage dilution water) is obtained, and the volume of the ammonia-containing water is reduced. In addition, the first recovered product, the second recovered product, and the dilution water can be reused.

In the water treatment device 3 shown in FIG. 3, the water treatment device 4 shown in FIG. 4, and the water treatment device 5 shown in FIG. 5, the concentrated water supplied to each membrane module becomes more concentrated as it moves from the first stage to the subsequent stages of the membrane module, and therefore becomes more concentrated. Since the water is ultimately concentrated to a high concentration, this method, which can reduce the osmotic pressure, makes it possible to concentrate the water to a level that was difficult to achieve with the conventional reverse osmosis membrane method due to the effects of osmotic pressure.

When distilled treated water is supplied to the first-stage membrane module 10a, a pressure of, for example, 7 MPa or less may be applied, and concentrated water may be supplied to the subsequent membrane module by the pressure applied to the first-stage membrane module 10a. The inlet pressure of the first space 14 in each membrane module is preferably in the range of 7 MPa or less, the inlet pressure of the second space 16 is preferably lower than the inlet pressure of the first space 14, and the inlet pressure of the second space 16 is more preferably 50% or less of the inlet pressure of the first space 14. This reduces the risk of damage to the semipermeable membrane due to pressure.

It is preferable to make the flow rate on the first space 14 side of each membrane module 10 greater than the flow rate on the second space 16 side. If the flow rate on the first space 14 side is equal to or less than the flow rate on the second space 16 side, the flow rate on the first space 14 side of the downstream membrane module may be insufficient. For example, the pump 18, inverter 20, valves 22a, 22b, 22c, valve 23, valves 32a, 32b, 32c, valve 32, etc. function as flow rate adjustment means that make the flow rate in the first space greater than the flow rate in the second space.

If the permeation flux is too large, the concentration polarization on the membrane surface will be large, which may lead to problems such as a high risk of fouling and excessive pressure. If the permeation flux is too small, the concentration efficiency may be poor. From these points of view, the permeation flux of each membrane module 10 is preferably in the range of 0.005 m/d to 0.05 m/d, and more preferably in the range of 0.015 m/d to 0.04 m/d. For example, the pump 18, inverter 20, valves 22a, 22b, and 22c, valve 23, valves 32a, 32b, and 32c, valve 32, etc. function as permeation flux adjustment means for controlling the permeation flux within the above range.

Note that the installation positions and number of valves are merely examples, and the number may be greater than those shown in Figures 3, 4, and 5, and may be installed in at least one of the other pipes. Also, a flowmeter as a flow measurement means for measuring the flow rate, or a pressure gauge as a pressure measurement means for measuring the pressure, may be installed in at least one of the pipes.

Figures 3, 4, and 5 are examples of device configurations, and the arrangement of the semipermeable membrane modules and the method of supplying the feed water, etc., may be changed as appropriate.

The water treatment device in Figure 5 is preferable because it passes water serially through the first space and the second space of each stage of the membrane module, and therefore can reduce the overall amount of water and the power required for the pump compared to the water treatment devices in Figures 3 and 4.

In the water treatment method and water treatment device according to this embodiment, a multi-stage membrane module may be used, and a membrane module unit having a plurality of membrane modules connected in parallel may be used as the membrane module of each stage. An example of a water treatment device with such a configuration is shown in Figures 6 and 7. The water treatment device shown in Figures 6 and 7 has a structure in which the first stage combines semipermeable membrane modules in four parallel rows, the second stage combines semipermeable membrane modules in four parallel rows, the third stage combines semipermeable membrane modules in two parallel rows, and the fourth stage combines semipermeable membrane modules in two parallel rows, connected in series in four stages.

The water treatment device 6 shown in FIG. 6 uses a distillation device 11 and a semipermeable membrane module connected in multiple stages having a first space (concentrated side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12 as a first recovery means for recovering at least one of ammonia and ammonium ions from ammonia-containing water as a first recovery product, and passes the distilled treated water from the distillation device 11 through the first space 14 of the first-stage semipermeable membrane module, pressurizes the first space 14 to cause the water contained in the distilled treated water to permeate the semipermeable membrane 12 to obtain concentrated water, and further obtains concentrated water using the semipermeable membrane module of the next stage or later, and passes a portion of the distilled treated water or a portion of the concentrated water through the second space 16 of the semipermeable membrane module of each stage to obtain dilution water. For example, the device includes a first-stage membrane module unit 100a, a second-stage membrane module unit 100b, a third-stage membrane module unit 100c, and a fourth-stage membrane module unit 100d as a second recovery means. The first-stage membrane module unit 100a, for example, includes four membrane modules connected in parallel, the second-stage membrane module unit 100b, for example, includes four membrane modules connected in parallel, the third-stage membrane module unit 100c, for example, includes two membrane modules connected in parallel, and the fourth-stage membrane module unit 100d, for example, includes two membrane modules connected in parallel. Each membrane module 10 has a first space 14 and a second space 16 separated by a semipermeable membrane 12. The water treatment device 6 may include a distilled water tank 84 for storing distilled water and a concentrated water tank 86 for storing concentrated water from the fourth-stage membrane module unit 100d. The membrane module unit 100 is a device that supplies distilled water to the first and second spaces of each membrane module of the first-stage membrane module unit, and sequentially supplies the concentrated water to the first and second spaces of each membrane module of the next-stage membrane module unit to perform concentration treatment.

In the water treatment device 6 of FIG. 6, a pipe 25 is connected to the inlet of the distillation device 11. A pipe 27 is connected to the first recovered product outlet of the distillation device 11. The distilled treated water outlet of the distillation device 11 and the inlet of the distilled treated water tank 84 are connected by a pipe 29. The outlet of the distilled treated water tank 84 and the first space inlet and the second space inlet of each membrane module of the first stage membrane module unit 100a are connected by a pipe 88 via a pump 18. The first space outlet of each membrane module of the first stage membrane module unit 100a and the first space inlet and the second space inlet of each membrane module of the second stage membrane module unit 100b are connected by a pipe 90. The first space outlet of each membrane module of the second stage membrane module unit 100b and the first space inlet and the second space inlet of each membrane module of the third stage membrane module unit 100c are connected by a pipe 94. The first space outlet of each membrane module of the third membrane module unit 100c and the first space inlet and second space inlet of each membrane module of the fourth membrane module unit 100d are connected by a pipe 98. The first space outlet of each membrane module of the fourth membrane module unit 100d and the inlet of the concentrated water tank 86 are connected by a pipe 104. A pipe 92 is connected to the second space outlet of each membrane module of the first membrane module unit 100a, a pipe 96 is connected to the second space outlet of each membrane module of the second membrane module unit 100b, a pipe 102 is connected to the second space outlet of each membrane module of the third membrane module unit 100c, and a pipe 106 is connected to the second space outlet of each membrane module of the fourth membrane module unit 100d, and the pipes 96, 102, and 106 may merge into the pipe 92.

The membrane module unit 100 is a device that uses a multi-stage membrane module unit equipped with a membrane module 10 having a first space 14 and a second space 16 separated by a semipermeable membrane 12, supplies distilled treated water to the first space and the second space of each membrane module of the first stage membrane module unit, sequentially supplies the concentrated water to the first space and the second space of each membrane module of the next stage membrane module unit, and pressurizes the first space 14 of the membrane module of each stage to permeate the water contained in the first space 14 through the semipermeable membrane 12 to the second space 16, concentrating the water. That is, in the membrane module unit 100, the distilled treated water is concentrated using the semipermeable membrane 12, and the concentrated water is further concentrated using the semipermeable membrane 12 of the next stage.

In the water treatment device 6, ammonia-containing water containing ammonia is supplied to the distillation device 11 through the pipe 25. Distillation is performed in the distillation device 11, and at least one of ammonia and ammonium ions is recovered from the ammonia-containing water as a first recovered product (first recovery process). The first recovered product is discharged through the pipe 27.

The distilled water obtained in the distillation apparatus 11 is stored in the distilled water tank 84 as necessary, and then pumped from the distilled water tank 84 through the piping 88 by the pump 18 to the first space 14 and the second space 16 of each membrane module of the first-stage membrane module unit 100a. In each membrane module of the first-stage membrane module unit 100a, the first space 14a is pressurized and the water contained in the first space 14 is permeated through the semipermeable membrane 12 into the second space 16 (concentration process (first stage)), and dilution water is obtained in the second space 16 (dilution process (first stage)). The dilution water obtained in the second space 16 of the first-stage membrane module 10 is stored in the dilution water tank as necessary through the piping 92, and then discharged outside the system.

The concentrated water obtained in the first space 14 of each membrane module of the first-stage membrane module unit 100a is sent through the pipe 90 to the first space 14 and the second space 16 of each membrane module of the second-stage membrane module unit 100b. In each membrane module of the second-stage membrane module unit 100b, the first space 14 is pressurized and the water contained in the first space 14 is permeated through the semipermeable membrane 12 into the second space 16 (concentration process (second stage)), and dilution water is obtained in the second space 16 (dilution process (second stage)). The dilution water obtained in the second space 16 of each membrane module of the second-stage membrane module unit 100b is stored in a dilution water tank as necessary through the pipe 96, and then discharged outside the system.

The concentrated water obtained in the first space 14 of each membrane module of the second-stage membrane module unit 100b is sent to the first space 14 and the second space 16 of each membrane module of the third-stage membrane module unit 100c through the pipe 94. In each membrane module of the third-stage membrane module unit 100c, the first space 14 is pressurized and the water contained in the first space 14 is permeated through the semipermeable membrane 12 into the second space 16 (concentration process (third stage)), and dilution water is obtained in the second space 16 (dilution process (third stage)). The dilution water obtained in the second space 16 of each membrane module of the third-stage membrane module unit 100c is stored in a dilution water tank as necessary through the pipe 102, and then discharged outside the system.

The concentrated water obtained in the first space 14 of each membrane module of the third-stage membrane module unit 100c is sent through the pipe 98 to the first space 14 and the second space 16 of each membrane module of the fourth-stage membrane module unit 100d. In each membrane module of the fourth-stage membrane module unit 100d, the first space 14 is pressurized and the water contained in the first space 14 is permeated through the semipermeable membrane 12 into the second space 16 (concentration process (fourth stage)), and dilution water is obtained in the second space 16 (dilution process (fourth stage)) (above, the second recovery process). The concentrated water obtained in the first space 14 of each membrane module of the fourth-stage membrane module unit 100d is stored in the concentrated water tank 86 as necessary through the pipe 104, and then discharged as the second recovery product. The dilution water obtained in the second space 16 of each membrane module of the fourth-stage membrane module unit 100d is stored in the dilution water tank as necessary through the pipe 106, and then discharged outside the system.

Here, the pump 18, pipes 88, 90, 94, 98, etc. function as a supply means for supplying distilled treated water or concentrated water to the first space 14 and the second space 16 of each membrane module of each stage of the membrane module units 100a, 100b, 100c, 100d.

The dilution water obtained in the second space 16 of each membrane module of the membrane module units 100a, 100b, 100c, and 100d of each stage may be discharged outside the system, or may be sent to a dilution water tank and stored as necessary, and then discharged outside the system or reused. At least a portion of the dilution water may be sent to the distillation treatment water tank 84 and mixed with the distillation treatment water in the distillation treatment water tank 84. At least a portion of the dilution water may be further processed, for example, by reverse osmosis membrane processing as described below.

In this manner, at least one of ammonia and ammonium ions is recovered as a first recovered product from the ammonia-containing water to be treated, and further, concentrated water in which the ions are concentrated (final stage concentrated water) is recovered as a second recovered product, and dilution water (dilution water of each stage) is obtained, and the volume of the ammonia-containing water is reduced. In addition, the first recovered product, the second recovered product, and the dilution water can be reused.

The water treatment device 7 shown in FIG. 7 uses a distillation device 11 and a semipermeable membrane module connected in multiple stages having a first space (concentrated side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12 as a first recovery means for recovering at least one of ammonia and ammonium ions from ammonia-containing water as a first recovery product, and passes the distilled treated water from the distillation device 11 through the first space 14 of the first-stage semipermeable membrane module, pressurizes the first space 14 to cause the water contained in the distilled treated water to permeate the semipermeable membrane 12 to obtain concentrated water, and further obtains concentrated water using the semipermeable membrane module of the next stage or later, and passes at least a portion of the concentrated water or at least a portion of the diluted water obtained from another semipermeable membrane module through the second space 16 of the semipermeable membrane module of each stage to obtain diluted water, for example, a first-stage membrane module unit 100a, a second-stage membrane module unit 100b, a third-stage membrane module unit 100c, and a fourth-stage membrane module unit 100d. The first stage membrane module unit 100a, for example, includes four membrane modules connected in parallel, the second stage membrane module unit 100b, for example, includes four membrane modules connected in parallel, the third stage membrane module unit 100c, for example, includes two membrane modules connected in parallel, and the fourth stage membrane module unit 100d, for example, includes two membrane modules connected in parallel. Each membrane module 10 has a first space 14 and a second space 16 separated by a semipermeable membrane 12. The water treatment device 7 may include a distilled water tank 84 for storing distilled water and a concentrated water tank 86 for storing concentrated water from the fourth stage membrane module unit 100d. The membrane module unit 100 is an apparatus that supplies distilled water to the first space of the first stage membrane module, and sequentially supplies the concentrated water to the first space of the next stage membrane module to perform concentration treatment.

In the water treatment device 7 of FIG. 7, a pipe 25 is connected to the inlet of the distillation device 11. A pipe 27 is connected to the first recovered product outlet of the distillation device 11. The distilled treated water outlet of the distillation device 11 and the inlet of the distilled treated water tank 84 are connected by a pipe 29. The outlet of the distilled treated water tank 84 and the first space inlet of each membrane module of the first stage membrane module unit 100a are connected by a pipe 108 via a pump 18. The first space outlet of each membrane module of the first stage membrane module unit 100a and the first space inlet of each membrane module of the second stage membrane module unit 100b are connected by a pipe 110. The first space outlet of each membrane module of the second stage membrane module unit 100b and the first space inlet of each membrane module of the third stage membrane module unit 100c are connected by a pipe 112. The first space outlet of each membrane module of the third stage membrane module unit 100c and the first space inlet of each membrane module of the fourth stage membrane module unit 100d are connected by a pipe 114. The first space outlet of each membrane module of the fourth-stage membrane module unit 100d is connected to the inlet of the concentrated water tank 86 by a pipe 116. A pipe 118 branched from the pipe 116 is connected to the second space inlet of each membrane module of the fourth-stage membrane module unit 100d. The second space outlet of each membrane module of the fourth-stage membrane module unit 100d is connected to the second space inlet of each membrane module of the third-stage membrane module unit 100c by a pipe 120. The second space outlet of each membrane module of the third-stage membrane module unit 100c is connected to the second space inlet of each membrane module of the second-stage membrane module unit 100b by a pipe 122. The second space outlet of each membrane module of the second-stage membrane module unit 100b is connected to the second space inlet of each membrane module of the first-stage membrane module unit 100a by a pipe 124. A pipe 126 is connected to the second space outlet of each membrane module of the first-stage membrane module unit 100a.

The membrane module unit 100 uses a multi-stage membrane module unit equipped with a membrane module 10 having a first space 14 and a second space 16 separated by a semipermeable membrane 12, supplies distilled water to the first space of each membrane module of the first stage membrane module unit, passes the concentrated water in series to the first space of each membrane module of the next stage membrane module unit, supplies at least a part of the concentrated water of each membrane module of the final stage membrane module unit to its own second space, passes the resulting diluted water in series to the second space 16 of each membrane module of the previous stage membrane module unit, and pressurizes the first space 14 of each stage to permeate the water contained in the first space 14 into the second space 16 through the semipermeable membrane 12, concentrating the water. That is, in the membrane module unit 100, the distilled water is concentrated using the semipermeable membrane 12, and the concentrated water is further concentrated using the semipermeable membrane 12 of the next stage.

In the water treatment device 7, ammonia-containing water containing ammonia is supplied to the distillation device 11 through the pipe 25. Distillation is performed in the distillation device 11, and at least one of ammonia and ammonium ions is recovered from the ammonia-containing water as a first recovered product (first recovery process). The first recovered product is discharged through the pipe 27.

The distilled water obtained in the distillation apparatus 11 is stored in the distilled water tank 84 as necessary, and then pumped from the distilled water tank 84 through the piping 108 to the first space 14 of each membrane module of the first-stage membrane module unit 100a. Meanwhile, the dilution water pumped through the second space 16 of each membrane module of the fourth-stage membrane module unit 100d, the second space 16 of each membrane module of the third-stage membrane module unit 100c, and the second space 16 of each membrane module of the second-stage membrane module unit 100b is pumped through the piping 124 to the second space 16 of each membrane module of the first-stage membrane module unit 100a. In each membrane module of the first-stage membrane module unit 100a, the first space 14 is pressurized and the water contained in the first space 14 is permeated into the second space 16 through the semipermeable membrane 12 (concentration process (first stage)), and dilution water is obtained in the second space 16 (dilution process (first stage)). The concentrated water obtained in the first space 14 of each membrane module of the first-stage membrane module unit 100a is sent to the first space 14 of each membrane module of the second-stage membrane module unit 100b through piping 110. The diluted water obtained in the second space 16 of each membrane module of the first-stage membrane module unit 100a is discharged outside the system through piping 126.

In each membrane module of the second-stage membrane module unit 100b, the dilution water sent via the second space 16 of each membrane module of the fourth-stage membrane module unit 100d described later and the second space 16 of each membrane module of the third-stage membrane module unit 100c is sent to the second space 16 of each membrane module of the second-stage membrane module unit 100b through the pipe 122. The first space 14 is pressurized and the water contained in the first space 14 is permeated into the second space 16 through the semipermeable membrane 12 (concentration process (second stage)), and dilution water is obtained in the second space 16 (dilution process (second stage)). The concentrated water obtained in the first space 14 of each membrane module of the second-stage membrane module unit 100b is sent to the first space 14 of each membrane module of the third-stage membrane module unit 100c through the pipe 112. The dilution water obtained in the second space 16 of each membrane module of the second-stage membrane module unit 100b is sent to the second space 16 of each membrane module of the first-stage membrane module unit 100a through piping 124.

In each membrane module of the third-stage membrane module unit 100c, the dilution water sent via the second space 16 of each membrane module of the fourth-stage membrane module unit 100d described later is sent through the pipe 120 to the second space 16 of each membrane module of the third-stage membrane module unit 100c. The first space 14 is pressurized and the water contained in the first space 14 is permeated through the semipermeable membrane 12 into the second space 16 (concentration process (third stage)), and dilution water is obtained in the second space 16 (dilution process (third stage)). The concentrated water obtained in the first space 14 of each membrane module of the third-stage membrane module unit 100c is sent through the pipe 114 to the first space 14 of each membrane module of the fourth-stage membrane module unit 100d. The dilution water obtained in the second space 16 of each membrane module of the third-stage membrane module unit 100c is sent through the pipe 122 to the second space 16 of each membrane module of the second-stage membrane module unit 100b.

In each membrane module of the fourth-stage membrane module unit 100d, the concentrated water obtained in the first space 14 of each membrane module of the fourth-stage membrane module unit 100d is sent to the second space 16 through the pipes 116 and 118 as follows. The first space 14 is pressurized and the water contained in the first space 14 is permeated through the semipermeable membrane 12 into the second space 16 (concentration process (fourth stage)), and dilution water is obtained in the second space 16 (dilution process (fourth stage)) (above, the second recovery process). The concentrated water obtained in the first space 14 of each membrane module of the fourth-stage membrane module unit 100d is stored in the concentrated water tank 86 as necessary through the pipe 116, and then discharged as the second recovery product. The concentrated water branched off from the pipe 116 is sent to the second space 16 of each membrane module of the fourth-stage membrane module unit 100d through the pipe 118. The dilution water obtained in the second space 16 of each membrane module of the fourth-stage membrane module unit 100d is sent through piping 120 to the second space 16 of each membrane module of the third-stage membrane module unit 100c.

Here, the pump 18, pipes 108, 110, 112, 114, 116, 118, 120, 122, 124, etc. function as supply means for supplying distilled treated water, concentrated water, or diluted water to the first space 14 and second space 16 of each membrane module of each stage of the membrane module units 100a, 100b, 100c, 100d.

The dilution water obtained in the second space 16 of each membrane module of the membrane module unit 100a may be discharged outside the system, or may be sent to a dilution water tank and stored as necessary, and then discharged outside the system or reused. At least a portion of the dilution water may be sent to the distillation treatment water tank 84 and mixed with the distillation treatment water in the distillation treatment water tank 84. At least a portion of the dilution water may be further processed, for example, by reverse osmosis membrane processing as described below.

In this manner, at least one of ammonia and ammonium ions is recovered as a first recovered product from the ammonia-containing water to be treated, and further, concentrated water in which the ions are concentrated (final stage concentrated water) is recovered as a second recovered product, and dilution water (dilution water of each stage) is obtained, and the volume of the ammonia-containing water is reduced. In addition, the first recovered product, the second recovered product, and the dilution water can be reused.

When distilled treated water is supplied to each membrane module of the first-stage membrane module unit 100a, a pressure of, for example, 7 MPa or less is applied, and concentrated water is supplied to the subsequent membrane module units by the pressure applied to each membrane module of the first-stage membrane module unit 100a. The inlet pressure of the first space 14 in each membrane module is preferably in the range of 7 MPa or less, the inlet pressure of the second space 16 is preferably lower than the inlet pressure of the first space 14, and the inlet pressure of the second space 16 is more preferably 50% or less of the inlet pressure of the first space 14. This reduces the risk of damage to the semipermeable membrane due to pressure.

It is preferable to set the flow rate on the first space 14 side of each membrane module 10 to be greater than the flow rate on the second space 16 side. If the flow rate on the first space 14 side is equal to or less than the flow rate on the second space 16 side, the flow rate on the first space 14 side of the downstream membrane module may be insufficient. For example, a pump 18 or the like functions as a flow rate adjustment means for making the flow rate on the first space greater than the flow rate on the second space.

If the permeation flux is too large, the concentration difference will be large, which may lead to problems such as a high risk of fouling and excessive pressure. If the permeation flux is too small, the concentration efficiency may be poor. From these points of view, the permeation flux of each membrane module 10 is preferably set in the range of 0.005 m/d to 0.05 m/d, and more preferably in the range of 0.015 m/d to 0.04 m/d. For example, the pump 18 or the like functions as a permeation flux adjustment means for controlling the permeation flux within the above range.

A valve may be installed in at least one of the pipes, and there are no particular restrictions on the location or number of valves. A flowmeter as a flow measurement means for measuring the flow rate and a pressure gauge as a pressure measurement means for measuring the pressure may be installed in at least one of the pipes.

Figures 6 and 7 are examples of device configurations, and the number of stages of semipermeable membrane modules, the number of parallel connections, the arrangement, the method of supplying the feed water, etc. may be changed as appropriate.

In order to concentrate the substance to be recovered in the distilled treated water as the second recovered product in the membrane module to a desired concentration, it is preferable to arrange the membrane modules in multiple stages in series. When using a multi-stage membrane module such as water treatment devices 3, 4, 5, 6, and 7, the number of stages of the membrane module can be determined based on the concentration of the target treated water, etc. For example, if it is desired to obtain treated water of a higher concentration from distilled treated water of a lower concentration, the number of stages of the membrane module unit can be increased.

When using a membrane module unit having multiple membrane modules connected in parallel as the membrane modules of each stage, as in water treatment devices 6 and 7, the number of membrane modules in each membrane module unit can be determined based on the flow rate of the distilled treated water, etc.

A concentrated water tank and a dilution water tank may be provided in one or more stages of the membrane module, or a concentrated water tank and a dilution water tank may be provided in each stage of the membrane module.

The ammonia-containing water to be treated is not particularly limited as long as it contains ammonium ions. Examples of ammonia-containing water include water that contains sulfate ions and ammonium ions, and examples of the water include wastewater discharged from semiconductor factories and chemical factories. In particular, in semiconductor factories, ammonia is used for cleaning wafers, and sulfuric acid is used for scrubbing to treat the ammonia. Therefore, the wastewater contains ammonium ions and sulfate ions. To effectively utilize the wastewater, the ammonia and sulfuric acid in the wastewater are recovered and reused.

The distillation apparatus 11 is not particularly limited as long as it can recover ammonia by distillation from ammonia-containing water that contains ammonia. Examples of the distillation apparatus 11 include a membrane distillation apparatus that recovers volatile ammonia through a gas permeable membrane, a reduced pressure distillation apparatus, and the like. For example, the ammonia recovered as a gas in the distillation apparatus 11 may be added to sulfuric acid and recovered as ammonium sulfate. This allows recovery of ammonium sulfate with high purity.

The semipermeable membrane 12 provided in the membrane module may be, for example, a reverse osmosis membrane (RO membrane), a forward osmosis membrane (FO membrane), a nanofiltration membrane (NF membrane), or the like. The semipermeable membrane is preferably a reverse osmosis membrane, a forward osmosis membrane, or a nanofiltration membrane.

The material constituting the semipermeable membrane 12 is not particularly limited, but examples include cellulose-based resins such as cellulose acetate-based resins, polysulfone-based resins such as polyethersulfone-based resins, polyamide-based resins, etc.

The shape of the semipermeable membrane 12 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.

The second recovered product is the dissolved solids (TDS) contained in the distilled water, such as inorganic salts such as sodium sulfate, calcium sulfate, sodium chloride, and calcium chloride.

The water treatment method and water treatment device according to this embodiment may include at least one pretreatment step (pretreatment means) prior to the first recovery step (first recovery means), such as a membrane treatment step (membrane treatment means) using a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), or the like, a reverse osmosis membrane treatment step (reverse osmosis membrane treatment means), a coagulation precipitation treatment step (coagulation precipitation treatment means), an organic matter removal treatment step (organic matter removal treatment means), a pH adjustment step (pH adjustment means), or a water temperature adjustment step (water temperature adjustment means).

For example, in the upstream stage of the distillation apparatus 11, pH adjustment and water temperature adjustment may be performed in order to efficiently recover the substance to be recovered by distillation. Although it depends on the water quality of the ammonia-containing water and the concentration conditions of the first recovery product, it is preferable that the pH of the ammonia-containing water is in the range of 10 to 12 and the water temperature is in the range of 30 to 40°C.

Before passing the water through the semipermeable membrane module downstream of the distillation apparatus 11, pH adjustment and water temperature adjustment may be performed again. The pH and water temperature when passing the water through the semipermeable membrane module may be determined based on the water quality of the ammonia-containing water, the material of the semipermeable membrane module, etc. For example, it is preferable that the pH of the ammonia-containing water is in the range of 3 to 8, and the water temperature is in the range of 15 to 40°C.

For example, the pH can be adjusted by adding a pH adjuster in a pH adjustment tank. Examples of pH adjusters include acids such as hydrochloric acid and sulfuric acid, and alkalis such as sodium hydroxide.

The water temperature can be adjusted, for example, by providing a water temperature adjustment tank and heating the tank with a heating device such as a heater, or by providing a heat exchanger.

The water treatment method and water treatment device according to this embodiment may further include, after the second recovery step (second recovery means), a water recovery step (water recovery means) in which at least a portion of the dilution water discharged from the second recovery step (second recovery means) is passed through a reverse osmosis membrane to obtain permeated water, and a return step (return means) in which concentrated water discharged from the reverse osmosis membrane is returned to the upstream stage of the semipermeable membrane module.
An example of a water treatment device having such a configuration is shown in FIG.

The water treatment device 8 in FIG. 8 includes the configuration of the water treatment device 1 in FIG. 1, and also includes a reverse osmosis membrane treatment device 200 as a water recovery means for passing at least a portion of the dilution water discharged from the membrane module 10 through a reverse osmosis membrane to obtain permeate water.

In the water treatment device 8 of FIG. 8, the second space outlet of the membrane module 10 and the inlet of the reverse osmosis membrane treatment device 200 are connected by piping 30. A piping 202 is connected to the RO permeate outlet of the reverse osmosis membrane treatment device 200. The RO concentrated water outlet of the reverse osmosis membrane treatment device 200 and the upstream side of the pump 18 in the piping 24 are connected by piping 204, which is a return means. The rest of the configuration is the same as that of the water treatment device 1 of FIG. 1. In the water treatment devices 2 to 7 of FIGS. 2 to 7, the reverse osmosis membrane treatment device 200 and the piping 204, which is a return means, may be provided.

In the water treatment device 8, the first recovery process and the second recovery process are performed in the same manner as in the water treatment device 1 of FIG. 1. The diluted water obtained in the second space 16 of the membrane module 10 is sent to the reverse osmosis membrane treatment device 200 through the pipe 30. In the reverse osmosis membrane treatment device 200, reverse osmosis membrane treatment is performed using a reverse osmosis membrane, and RO concentrated water and RO permeate water are obtained (water recovery process). The obtained RO permeate water is discharged outside the system through the pipe 202 and can be reused. The RO concentrated water is returned through the pipe 204 to the upstream stage of the membrane module 10, for example, the pipe 24, and mixed with the distilled water (return process). The RO concentrated water may be returned to the upstream stage of the distillation device 11 and mixed with ammonia-containing water.

In this manner, at least one of ammonia and ammonium ions is recovered as a first recovered product from the ammonia-containing water to be treated, and further, concentrated water in which the ions are concentrated is recovered as a second recovered product, thereby reducing the volume of the ammonia-containing water. The first recovered product and the second recovered product can be reused. In addition, by further subjecting the dilution water to reverse osmosis membrane treatment, the water quality can be made more suitable for reuse. By returning the RO concentrated water to the front stage of the semipermeable membrane module, the amount of wastewater can be reduced.

1, 2, 3, 4, 5, 6, 7, 8 Water treatment device, 10, 10a, 10b, 10c Membrane module, 11 Distillation device, 12, 12a, 12b, 12c Semipermeable membrane, 14, 14a, 14b, 14c First space, 16, 16a, 16b, 16c Second space, 18 Pump, 20 Inverter, 22, 22a, 22b, 22c, 23, 32, 32a, 32b, 32c Valve, 24, 25, 26, 27, 28, 29, 30, 34, 36, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 88, 90, 92, 94, 96, 98, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 202, 204 Piping, 60a, 60b, 60c, 62a, 62b, 62c Dilution water tank, 84 Distillation treatment water tank, 86 Concentration water tank, 100, 100a, 100b, 100c, 100d Membrane module unit, 200 Reverse osmosis membrane treatment equipment.

Claims (6)

A water treatment method for recovering at least one of ammonia and ammonium ions from ammonia-containing water, comprising the steps of:
a first recovery step of recovering at least one of the ammonia and the ammonium ion from the ammonia-containing water as a first recovery product using a distillation apparatus;
a second recovery step in which a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane is used to pass the distilled water containing dissolved solid components obtained in the distillation apparatus through the first space, and the first space is pressurized to cause the water contained in the distilled water to permeate through the semipermeable membrane, thereby obtaining a concentrated water containing the dissolved solid components as a second recovered product, and a part of the distilled water or at least a part of the concentrated water is passed through the second space to obtain dilution water;
Including,
The water treatment method according to the present invention, wherein the ammonia-containing water has a sulfate ion concentration of 6000 mg/L or more and an ammonium ion concentration of 2000 mg/L or more . A water treatment method for recovering at least one of ammonia and ammonium ions from ammonia-containing water, comprising the steps of:
a first recovery step of recovering at least one of the ammonia and the ammonium ion from the ammonia-containing water as a first recovery product using a distillation apparatus;
a second recovery step in which distilled water containing dissolved solid components obtained in the distillation apparatus is passed through a first space of a semipermeable membrane module of a first stage using semipermeable membrane modules connected in a plurality of stages, each having a first space and a second space separated by a semipermeable membrane, and concentrated water is obtained by pressurizing the first space to cause the water contained in the distilled water to permeate through the semipermeable membrane, and the concentrated water is further obtained as a second recovered product using a semipermeable membrane module of a subsequent stage or later to obtain concentrated water containing dissolved solid components , and dilution water is obtained by passing a portion of the distilled water or at least a portion of the concentrated water or at least a portion of dilution water obtained from another semipermeable membrane module through the second space of the semipermeable membrane module of each stage;
Including,
The water treatment method according to the present invention, wherein the ammonia-containing water has a sulfate ion concentration of 6000 mg/L or more and an ammonium ion concentration of 2000 mg/L or more . The water treatment method according to claim 1 or 2,
After the second recovery step, a water recovery step of passing at least a portion of the dilution water discharged from the second recovery step through a reverse osmosis membrane to obtain a permeate;
A returning step of returning the concentrated water discharged from the reverse osmosis membrane to a stage upstream of the semipermeable membrane module;
The water treatment method further comprises: A water treatment device for recovering at least one of ammonia and ammonium ions from ammonia-containing water, comprising:
a first recovery means for recovering at least one of the ammonia and the ammonium ions from the ammonia - containing water as a first recovery product using a distillation apparatus;
a second recovery means for passing the distilled water containing dissolved solid components obtained in the distillation apparatus through the first space using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, pressurizing the first space to cause the water contained in the distilled water to permeate through the semipermeable membrane, thereby obtaining a concentrated water containing the dissolved solid components as a second recovered product, and passing a part of the distilled water or at least a part of the concentrated water through the second space to obtain dilution water;
Equipped with
2. The water treatment device according to claim 1, wherein the ammonia-containing water has a sulfate ion concentration of 6000 mg/L or more and an ammonium ion concentration of 2000 mg/L or more . A water treatment device for recovering at least one of ammonia and ammonium ions from ammonia-containing water, comprising:
a first recovery means for recovering at least one of the ammonia and the ammonium ions from the ammonia - containing water as a first recovery product using a distillation apparatus;
a second recovery means for using semipermeable membrane modules connected in a plurality of stages, each having a first space and a second space separated by a semipermeable membrane, passing distilled water containing dissolved solid components obtained in the distillation apparatus through a first space of a first stage semipermeable membrane module, pressurizing the first space to cause the water contained in the distilled water to permeate through the semipermeable membrane, thereby obtaining concentrated water, which is further recovered using a semipermeable membrane module in a subsequent stage or later to obtain concentrated water containing the dissolved solid components as a second recovered product, and passing a portion of the distilled water or at least a portion of the concentrated water, or at least a portion of dilution water obtained from another semipermeable membrane module, through the second space of the semipermeable membrane module in each stage to obtain dilution water;
Equipped with
2. The water treatment device according to claim 1, wherein the ammonia-containing water has a sulfate ion concentration of 6000 mg/L or more and an ammonium ion concentration of 2000 mg/L or more . The water treatment device according to claim 4 or 5 ,
a water recovery means for passing at least a portion of the dilution water discharged from the second recovery means through a reverse osmosis membrane to obtain a permeate, the water recovery means being disposed downstream of the second recovery means;
A return means for returning concentrated water discharged from the reverse osmosis membrane to a stage upstream of the semipermeable membrane module;
The water treatment device further comprises:

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