TW202325662A - Water treatment device and water treatment method - Google Patents

Abstract

An object of the invention is to provide a water treatment device and a water treatment method that are capable of recovering valuable materials from wastewater in high concentrations. A water treatment device (1) for recovering valuable materials from wastewater comprises a nanofiltration device (11) which uses a nanofiltration membrane to obtain an NF permeate and an NF concentrate from a wastewater, and a semipermeable membrane processing unit which, by using a membrane module (10) having a first space (14) and a second space (16) separated by a semipermeable membrane (12), obtains a concentrate by flowing the NF concentrate into the first space (14) and pressurizing the first space (14) so that the water contained in the NF concentrate passes through the semipermeable membrane (12), and obtains a diluted water by passing at least a portion of the NF concentrate or at least a portion of the concentrate into the second space (16).

Description

Water treatment device and water treatment method

The present invention relates to a water treatment device and a water treatment method for recovering valuable substances from wastewater.

In recent years, methods of recovering valuable substances from waste water discharged from semiconductor factories and the like using evaporation methods such as evaporators or thin film distillation have been adopted. However, the evaporation method requires a large amount of energy, so a method of reducing the volume of wastewater by using a reverse osmosis membrane method in the preceding stage of the evaporation method as in Patent Document 1 is generally used.

On the other hand, as for the method of concentrating the ions contained in the wastewater at a high concentration, we have developed a method like Patent Document 2 in which the hard components or suspended matter components of the concentrated solution of the reverse osmosis membrane module are separated by a nanofiltration membrane or an ultrafiltration membrane. After the filter membrane is removed, the method of concentrating its permeated water with a semi-permeable membrane module. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 10-323664 [Patent Document 2] Japanese Patent Laid-Open No. 2021-045736

[Problem to be solved by the invention]

An object of the present invention is to provide a water treatment device and a water treatment method capable of recovering valuable substances from wastewater at a high concentration. [means to solve the problem]

The present invention is a water treatment device, which recovers valuable substances from drainage, and is characterized by comprising: a nanofiltration mechanism, which uses a nanofiltration membrane for the drainage to obtain NF (Nano Filtration, nanofiltration) permeated water and NF Concentrated water; and a semipermeable membrane treatment mechanism, which uses a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, so that the NF concentrated water flows into the first space, and the first space pressurizing, so that the moisture contained in the NF concentrated water permeates through the semi-permeable membrane to obtain concentrated water, and at the same time, let a part of the NF concentrated water or at least a part of the concentrated water flow into the second space to obtain dilution water .

The present invention is a water treatment device, which recovers valuable substances from drainage, and is characterized by comprising: a nanofiltration mechanism, which uses a nanofiltration membrane for the drainage to obtain NF permeated water and NF concentrated water; and semipermeable membrane treatment A mechanism that uses a semi-permeable membrane module that has a first space and a second space separated by a semi-permeable membrane and is connected into a plurality of stages, so that the NF concentrated water flows into the first space of the semi-permeable membrane module of the first stage , the first space is pressurized, so that the moisture contained in the NF concentrated water permeates through the semipermeable membrane to obtain concentrated water, and the concentrated water is obtained from the concentrated water by using the semipermeable membrane module after the next stage, and at the same time Let the NF concentrated water or at least a part of the concentrated water or at least a part of the dilution water obtained from other semi-permeable membrane modules circulate to the second space of the semi-permeable membrane modules of each section to obtain dilution water.

In this water treatment device, it is further provided with: a return mechanism, which returns at least a part of the dilution water obtained by the semi-permeable membrane treatment mechanism to the front stage of the nanofiltration mechanism, which is a preferred aspect.

In the water treatment device, the wastewater preferably contains 2000 mg/L or more of ammonium ions, 6000 mg/L or more of sulfate ions, and 5 mg/L or more of silica.

In the water treatment device, the nanofiltration membrane, under the conditions of effective pressure on the membrane surface of 1MPa, 25°C, and pH 7, has a silicon dioxide rejection rate in the range of 0 to 20%, ammonium ion rejection rate and sulfate ion rejection rate It is a preferable aspect in the range of 90% to 100%.

In this water treatment device, it is further provided with a pH adjustment mechanism that adjusts the pH of the wastewater to a range of 4 to 8 in the preceding stage of the nanofiltration mechanism, which is a preferable aspect.

In this water treatment device, it is further provided with a temperature adjustment mechanism that adjusts the temperature of the drainage to a range of 20° C. to 35° C. in the preceding stage of the nanofiltration mechanism, which is a preferable aspect.

The present invention is a water treatment method, which recovers valuable substances from drainage, and is characterized by comprising: a nanofiltration step, which uses a nanofiltration membrane for the drainage to obtain NF permeated water and NF concentrated water; and semipermeable membrane treatment A step of using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, allowing the NF concentrated water to flow into the first space, pressurizing the first space, and making the NF concentrated water The contained water permeates through the semi-permeable membrane to obtain concentrated water, and at the same time, a part of the NF concentrated water or at least a part of the concentrated water is circulated into the second space to obtain dilution water.

The present invention is a water treatment method, which recovers valuable substances from drainage, and is characterized by comprising: a nanofiltration step, which uses a nanofiltration membrane for the drainage to obtain NF permeated water and NF concentrated water; and semipermeable membrane treatment The step of using a semi-permeable membrane module having a first space and a second space separated by a semi-permeable membrane and connecting multiple sections, so that the NF concentrated water flows into the first space of the semi-permeable membrane module of the first section , the first space is pressurized, so that the moisture contained in the NF concentrated water permeates through the semipermeable membrane to obtain concentrated water, and the concentrated water is obtained from the concentrated water by using the semipermeable membrane module after the next stage, and at the same time Let the NF concentrated water or at least a part of the concentrated water or at least a part of the dilution water obtained from other semi-permeable membrane modules circulate to the second space of the semi-permeable membrane modules of each section to obtain dilution water.

In the water treatment method, it is a preferable aspect to return at least a part of the dilution water obtained in the semipermeable membrane treatment step to the front stage of the nanofiltration step.

In the water treatment method, it is preferable that the wastewater contains ammonium ions of 2000 mg/L or more, sulfate ions of 6000 mg/L or more, and silica of 5 mg/L or more.

In the water treatment method, the nanofiltration membrane, under the conditions of effective pressure on the membrane surface of 1MPa, 25°C, and pH7, has a silicon dioxide blocking rate in the range of 0-20%, ammonium ion blocking rate and sulfate ion blocking rate It is a preferable aspect in the range of 90% to 100%.

In the water treatment method, further comprising: a pH adjustment step, which is a preferable aspect of adjusting the pH of the wastewater to a range of 4-8 in the preceding stage of the nanofiltration step.

In the water treatment method, further comprising: a temperature adjustment step, which is a better aspect of adjusting the temperature of the drainage to a range of 20° C. to 35° C. in the preceding stage of the nanofiltration step.

In the water treatment method, further comprising: a pH adjustment step, which adjusts the pH of the drainage to a range of 7-9; in the nanofiltration step, uses the nanofiltration membrane for the pH-adjusted drainage to The NF permeated water and the NF concentrated water are obtained; the drainage contains more than 1000 mg/L of ammonium ions, more than 1000 mg/L of divalent anions, and more than 5 mg/L of silicon dioxide, which is a better aspect.

In the water treatment method, the pH of the wastewater will be adjusted to a range of 8-9 in the pH adjustment step; and further comprising: an ammonia treatment step, which is used to treat the ammonia gas discharged in the nanofiltration step , which is a better form.

In the water treatment method, further comprising: a semipermeable membrane treatment step, which is a preferred aspect of using a semipermeable membrane for the NF concentrated water to obtain concentrated water and dilution water in the latter stage of the nanofiltration step.

In the water treatment method, the nanofiltration membrane, under the conditions of effective pressure on the membrane surface of 1MPa, 25°C, and pH7, has a silicon dioxide blocking rate in the range of 0-20%, ammonium ion blocking rate and sulfate ion blocking rate It is a preferable aspect in the range of 90% to 100%.

In the water treatment device, it is further equipped with: a pH adjustment mechanism, which adjusts the pH of the drainage to a range of 7-9; the nanofiltration mechanism, which uses the nanofiltration membrane for the pH-adjusted drainage to obtain The mechanism of the NF permeated water and the NF concentrated water; the drainage, containing more than 1000 mg/L of ammonium ions, containing more than 1000 mg/L of divalent anions, and containing more than 5 mg/L of silicon dioxide, is a better aspect .

In the water treatment device, the pH of the wastewater is adjusted to a range of 8-9 in the pH adjustment mechanism; and it is further equipped with: an ammonia treatment mechanism, which is used to process the ammonia gas discharged by the nanofiltration mechanism, for the better form.

In the water treatment device, it is further equipped with a semipermeable membrane treatment mechanism, which is a preferred aspect of using a semipermeable membrane for the NF concentrated water to obtain concentrated water and dilution water in the rear stage of the nanofiltration mechanism.

In the water treatment device, the nanofiltration membrane, under the conditions of effective pressure on the membrane surface of 1MPa, 25°C, and pH 7, has a silicon dioxide rejection rate in the range of 0 to 20%, ammonium ion rejection rate and sulfate ion rejection rate It is a preferable aspect in the range of 90% to 100%. [Efficacy of the invention]

According to the present invention, it is possible to provide a water treatment device and a water treatment method capable of recovering valuable substances from waste water at a high concentration.

Embodiments of the present invention will be described below. This embodiment is an example of implementing the present invention, and the present invention is not limited to this embodiment.

The schematic structure of an example of the water treatment apparatus which concerns on embodiment of this invention is shown in FIG. 1, and it demonstrates about this structure.

The water treatment apparatus 1 shown in FIG. 1 is an apparatus for recovering valuable substances from waste water such as waste water containing ammonia. The water treatment device 1 is equipped with: a nanofiltration device 11, which is used as a nanofiltration mechanism, and uses a nanofiltration membrane for ammonia-containing wastewater to obtain NF (Nano Filtration, nanofiltration) permeated water and NF concentrated water; and such as a membrane Module 10, as a semipermeable membrane treatment mechanism, uses a semipermeable membrane module with a first space (concentration side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12, so that the nanofiltration device 11 The NF concentrated water flows into the first space 14, and the first space 14 is pressurized, so that the moisture contained in the NF concentrated water permeates through the semipermeable membrane 12 to obtain concentrated water, and at the same time, a part of the NF concentrated water is circulated into the second space 16 to obtain dilution water. The water treatment device 1 may also be equipped with a NF concentrated water tank for storing NF concentrated water between the nanofiltration 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 nanofiltration device 11 through a permeation pump 21 . The pipe 27 was connected to the NF permeated water outlet of the nanofiltration device 11 . The NF concentrated water outlet of the nanofiltration device 11 is connected to the first space inlet of the membrane module 10 through the pump 18 by the pipe 24, and the pipe 26 branched from the pipe 24 on the downstream side of the pump 18 is connected to the membrane through the valve 22. The entrance to the second space of the module 10. The outlet of the first space of the film module 10 is connected to the pipe 28 through the valve 23 , and the outlet of the second space of the film module 10 is connected to the upstream side of the pump 21 in the pipe 25 through the pipe 30 .

The pump 18 is, for example, a booster pump that "drives at a rotational speed corresponding to the input drive frequency, sucks in NF concentrated water, and discharges it to the membrane module 10 under pressure". The pump 18 is provided with, for example, an inverter 20 that outputs a driving frequency corresponding to an input command signal to the pump 18 . The pump 21 is, for example, a booster pump that "drives at a rotational speed corresponding to the input drive frequency, sucks ammonia-containing wastewater, and discharges it to the nanofiltration device 11 under pressure." The valve 22 and the valve 23 are, for example, valves that can manually or automatically adjust the degree of opening and closing.

Membrane module 10, "has a first space 14 and a second space 16 separated by a semi-permeable membrane 12, so that NF concentrated water flows from the entrance of the first space of the membrane module 10 to the first space 14, and from the second The entrance of the space flows into the second space 16, and by pressurizing the first space 14, the moisture contained in the NF concentrated water in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 to concentrate the water. installation. That is, in the water treatment device 1 , the NF concentrated water is concentrated by the semipermeable membrane 12 . The thin film module 10 is a device that "supplies NF concentrated water to both the first space 14 and the second space 16 of the thin film module 10 to perform concentration treatment".

In the water treatment device 1 , water to be treated, that is, ammonia-containing wastewater containing ammonia, is supplied to the nanofiltration device 11 by the pump 21 through the pipe 25 . In the nanofiltration device 11 , a nanofiltration membrane is used for ammonia-containing wastewater to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 . The NF permeated water can be discharged out of the system, or discharged into rivers, etc., and advanced water treatment methods can be further set up to recycle the water.

The NF concentrated water obtained in the nanofiltration device 11 is pressurized and delivered to the first space 14 by the pump 18 from the inlet of the first space of the membrane module 10 through the piping 24 when the valve 23 is opened. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. In addition, the NF concentrated water is sent from the inlet of the second space of the membrane module 10 to flow into the second space 16 through the pipe 26 branched from the pipe 24 with the valve 22 open. Part of the moisture contained in the pressurized NF concentrated water permeates from the first space 14 to the second space 16 through the semipermeable membrane 12 . At this time, since most of the ions contained in the NF concentrated water cannot permeate the semipermeable membrane 12, the water in the first space 14 that has not permeated the semipermeable membrane 12 is concentrated. On the other hand, in the second space 16, a part of the NF concentrated water flowing through the pipe 26 merges with the permeated water having a low ion concentration that has permeated the semipermeable membrane 12, thereby exhibiting a dilution effect. The concentrated water obtained in the first space 14 is discharged from the outlet of the first space through the pipe 28; the diluted water obtained in the second space 16 is discharged from the outlet of the second space through the pipe 30; at least a part of the diluted water can also be sent to Return to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the piping 25 (return step). Here, in the membrane module 10, the first space 14 is pressurized, and the moisture contained in the NF concentrated water in the first space 14 permeates into the second space 16 through the semi-permeable membrane 12, and then in the first space 14 to obtain concentrated water (concentration step), and at the same time obtain dilution water (dilution step) in the second space 16 (the above is the semi-permeable membrane treatment step).

Here, the pipes 24 , 26 , the pump 18 and the like function as “a supply mechanism for supplying NF concentrated water to both the first space 14 and the second space 16 of the membrane module 10 ”. The piping 30 and the like function as "a return mechanism for returning at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second space 16 can be discharged out of the system through the pipe 30, and can also be discharged out of the system after being transported to the dilution water tank for storage as needed, and can also be reused. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a part of the dilution water.

In the above-mentioned manner, concentrated water of at least one of ammonia and ammonium ions was recovered from the treatment object (that is, ammonia-containing wastewater containing ammonia), and volume reduction treatment of ammonia-containing wastewater was carried out. In addition, NF permeated water, concentrated water, and diluted water can be reused.

By making the NF concentrated water flow into 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 semi-permeable membrane 12 can be reduced, and further Concentrate high-concentration ions in NF concentrated water with less energy consumption. That is, NF concentrated water containing high-concentration ions can be concentrated at low cost, and the amount of waste liquid with high ion concentration can be reduced.

Occasionally, due to the scale component contained in the wastewater discharged from semiconductor factories, etc., the permeable membrane may be blocked and the concentration may be difficult when high concentration is performed by semi-permeable membrane treatment. For example, when the wastewater contains silicon dioxide (SiO ₂ ), it is advisable to remove the silicon dioxide by pre-treatment with a semi-permeable membrane. However, if the concentration of silicon dioxide is too high, sometimes it is difficult to use dispersants and other agents. correspond to these issues.

In the water treatment device and water treatment method of this embodiment, even if the wastewater contains silicon dioxide, the nanofiltration device 11 can still be used to selectively permeate the silicon dioxide in the wastewater through the nanofiltration membrane, and By making the NF concentrated water whose concentration of silicon dioxide has been reduced flow into the first space 14 or both sides of the first space 14 and the second space 16 of the thin film module 10, the target substance to be concentrated can be stably and highly concentrated.

At least a part of the dilution water obtained in the second space 16 is sent back to the front section of the nanofiltration device 11, which is a preferred form; A better way: 70-100% of the dilution water is sent back to the front section of the nanofiltration device 11, which is the best way. By making the dilution water discharged from the membrane module 10 above a predetermined amount circulate back to the front stage of the nanofiltration device 11, even if silicon dioxide is contained in the ammoniacal wastewater, the content of the ammonia-containing wastewater supplied to the nanofiltration device 11 can still be reduced. The ratio of silica concentration to ammonium ion concentration in ammonia wastewater can reduce the risk of silica scaling in the concentration step of semi-permeable membrane treatment.

Regarding the adjustment method for adjusting the supply flow rate of NF concentrated water to the membrane module 10, the flow rate of permeate water, and the flow rate of concentrated water, for example, the following method may be implemented.

An inverter 20 for controlling the driving frequency is installed on the pump 18 to adjust the supply flow rate of NF concentrated water to the membrane module 10 . It is preferable to install the frequency converter 20 on the pump 18, but it is not necessary to install it. As long as "the NF concentrated water is supplied to both the first space 14 side and the second space 16 side, a valve 22 is set before the entrance of the second space 16, and a valve 23 is set at the exit of the first space 14 to manually or automatically adjust the valve. 22 and the opening of the valve 23 to adjust the ratio of the water supply flow to the first space 14 side to the water supply flow to the second space 16 side.

When the permeate water flow rate and concentrated water flow rate are insufficient, it is sufficient to increase the frequency of the frequency converter 20 of the pump 18 to increase the supply of NF concentrated water.

The pipe 28 at the outlet of the first space 14 is provided with a valve 23 with adjustable opening and closing degree. By using the opening degree of the valve 23, the concentrated water flow rate or the pressure at the entrance of the first space 14 and the outlet of the first space 14 can be adjusted.

Through these operations, the pressure and various flow rates on the side of the first space 14 can be adjusted to a predetermined value.

In addition, the NF concentrated water may be supplied to the first space 14 side and the second space 16 side by separate pumps. When supplying NF concentrated water with separate pumps, it is also possible to install an inverter to control the drive frequency for each pump.

By passing the NF concentrated water with the same or similar concentration to both the first space 14 side and the second space 16 side, the osmotic pressure generated by the semi-permeable membrane 12 can be reduced, thereby reducing the required pressure. As a result, NF concentrated water can be concentrated to a concentration that cannot be concentrated by the conventional reverse osmosis membrane method.

If so, valuable substances can be recovered in high concentrations from ammonia-containing wastewater. In addition, even if silica is contained in ammoniated wastewater, by performing semi-permeable membrane treatment on NF concentrated water whose silica concentration has been reduced, the risk of silica scale precipitation in the concentration step of semi-permeable membrane treatment can be reduced.

The schematic structure of another example of the water treatment apparatus which concerns on embodiment of this invention is shown in FIG. 2, and it demonstrates about this structure.

The water treatment device 2 shown in Fig. 2 is equipped with: a nanofiltration device 11, which is used as a nanofiltration mechanism, and uses a nanofiltration membrane to obtain NF permeated water and NF concentrated water for drainage such as ammonia-containing drainage; and, for example, a membrane Module 10, as a semipermeable membrane treatment mechanism, uses a semipermeable membrane module with a first space (concentration side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12, so that the nanofiltration device 11 The NF concentrated water flows into the first space 14, the first space 14 is pressurized, and the moisture contained in the NF concentrated water permeates through the semipermeable membrane 12 to obtain concentrated water, and at the same time, at least a part of the concentrated water is circulated into the second space 16 to obtain dilution water. The water treatment device 2 may also be equipped with a NF concentrated water tank for storing NF concentrated water between the nanofiltration device 11 and the membrane module 10 .

In the water treatment device 2 shown in FIG. 2 , a pipe 25 is connected to the inlet of the nanofiltration device 11 through a permeation pump 21 . The pipe 27 was connected to the NF permeated water outlet of the nanofiltration device 11 . The NF concentrated water outlet of the nanofiltration device 11 is connected to the first space inlet of the membrane module 10 through a pump 18 through a pipe 24 . A pipe 28 is connected to the outlet of the first space of the film module 10 through a valve 23 . A pipe 34 branched from the pipe 28 on the upstream side of the valve 23 is connected to the second space inlet of the film module 10 through the valve 32 . The outlet of the second space of the thin film module 10 is connected to the upstream side of the pump 21 in the piping 25 through the piping 36 .

The pump 18 is, for example, a booster pump that "drives at a rotational speed corresponding to the input drive frequency, sucks in NF concentrated water, and discharges it to the membrane module 10 under pressure". The pump 18 is provided with, for example, an inverter 20 that outputs a driving frequency corresponding to an input command signal to the pump 18 . The pump 21 is, for example, a booster pump that "drives at a rotational speed corresponding to the input drive frequency, sucks ammonia-containing wastewater, and discharges it to the nanofiltration device 11 under pressure." The valve 23 and the valve 32 are, for example, valves that can manually or automatically adjust the degree of opening and closing.

The thin film module 10 is "having a first space 14 and a second space 16 separated by a semi-permeable membrane 12, so that NF concentrated water flows from the first space entrance of the thin film module 10 to the first space 14, and at the same time makes the thin film module At least a part of the concentrated water discharged from the first space outlet of the first space 14 of the group 10 flows from the second space inlet of the membrane module 10 to the second space 16, pressurizing the first space 14, thereby making the second space 16 The moisture contained in the NF concentrated water in the first space 14 permeates through the semi-permeable membrane 12 to the second space 16 to concentrate the water. That is, in the water treatment device 2 , the NF concentrated water is concentrated by the semipermeable membrane 12 . The thin film module 10 is "supply NF concentrated water to the first space 14 of the thin film module 10, supply at least a part of the concentrated water obtained from the outlet of the first space 14 to the second space 16 of the thin film module 10, To carry out concentration processing "device.

In the water treatment device 2 , water to be treated, that is, ammonia-containing wastewater containing ammonia, is supplied to the nanofiltration device 11 by the pump 21 through the pipe 25 . In the nanofiltration device 11 , a nanofiltration membrane is used for ammonia-containing wastewater to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

The NF concentrated water obtained in the nanofiltration device 11 is pressurized and delivered to the first space 14 by the pump 18 from the inlet of the first space of the membrane module 10 through the piping 24 when the valve 23 is opened. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. Part of the moisture contained in the pressurized NF concentrated water permeates from the first space 14 to the second space 16 through the semipermeable membrane 12 . At this time, since most of the ions and the like cannot permeate the semipermeable membrane 12, the water in the first space 14 that has not permeated the semipermeable membrane 12 is concentrated. On the other hand, in the second space 16, part of the concentrated water flowing through the pipe 34 merges with the permeated water with a lower ion concentration that has permeated the semipermeable membrane 12 to exert a dilution effect. The concentrated water obtained in the first space 14 is discharged from the outlet of the first space through the pipe 28, and at least a part of the concentrated water passes through the pipe 34 branched from the pipe 28 when the valve 32 is open, and is transferred from the thin film module 10 The second space inlet conveys and circulates to the second space 16 . The dilution water that can also be obtained in the second space 16 is discharged from the outlet of the second space through the piping 36, and at least a part of the dilution water is sent back to the front stage of the nanofiltration device 11, that is, to the pump 21 in the piping 25. Upstream side (return step). Here, in the membrane module 10, the first space 14 is pressurized, and the moisture contained in the NF concentrated water in the first space 14 permeates into the second space 16 through the semi-permeable membrane 12, and then in the first space 14 to obtain concentrated water (concentration step), and at the same time obtain dilution water (dilution step) in the second space 16 (the above is the semi-permeable membrane treatment step).

Here, the pipes 24, 28, 34, pump 18, etc. play a role of "supplying NF concentrated water to the first space 14 of the membrane module 10 and supplying at least a part of the concentrated water obtained from the outlet of the first space 14 to the The function of the "supply mechanism" of the second space 16 of the film module 10. The piping 36 and the like function as "a return mechanism for returning at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second space 16 can be discharged out of the system through the pipe 36, and can also be discharged out of the system after being transported to the dilution water tank for storage as needed, and can also be reused. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a part of the dilution water.

In the above-mentioned manner, concentrated water of at least one of ammonia and ammonium ions was recovered from the treatment object (that is, ammonia-containing wastewater containing ammonia), and volume reduction treatment of ammonia-containing wastewater was carried out. In addition, NF permeated water, concentrated water, and diluted water can be reused.

By making the NF concentrated water flow into the first space 14 of the membrane module 10, and making at least a part of the concentrated water obtained in the first space 14 flow into the second space 16, the first space of the semipermeable membrane 12 can be reduced. The osmotic pressure difference between the side of the space 14 and the side of the second space 16 further concentrates high-concentration ions in the NF concentrated water with less energy consumption. That is, NF concentrated water containing high-concentration ions can be concentrated at low cost, and the amount of waste liquid with high ion concentration can be reduced.

Regarding the adjustment method for adjusting the supply flow rate of NF concentrated water to the membrane module 10, the flow rate of permeate water, and the flow rate of concentrated water, for example, the following method may be implemented.

An inverter 20 for controlling the driving frequency is installed on the pump 18 to adjust the supply flow rate of NF concentrated water to the membrane module 10 . It is preferable to install the frequency converter 20 on the pump 18, but it is not necessary to install it. As long as "the supply of NF concentrated water is implemented on the side of the first space 14, a valve 23 is set at the outlet of the first space 14, and a valve 32 is set before the entrance of the second space 16, and the valve 23 and the valve 32 are adjusted manually or automatically. The degree of opening is to adjust the ratio of the flow rate of water supplied to the first space 14 side to the flow rate of water supplied to the second space 16 side.

When the permeate water flow rate and concentrated water flow rate are insufficient, it is sufficient to increase the frequency of the frequency converter 20 of the pump 18 to increase the supply of NF concentrated water.

The pipe 28 at the outlet of the first space 14 is provided with a valve 23 with adjustable opening and closing degree. By using the opening degree of the valve 23, the concentrated water flow rate or the pressure at the entrance of the first space 14 and the outlet of the first space 14 can be adjusted.

Through these operations, the pressure and various flow rates on the side of the first space 14 can be adjusted to a predetermined value.

In addition, a concentrated water tank for storing concentrated water may be provided in the middle of the piping 34, and the NF concentrated water may be supplied to the first space 14 side and the concentrated water may be supplied to the second space 16 side by separate pumps. When supplying NF concentrated water and concentrated water with separate pumps, an inverter for controlling the driving frequency may be provided for each pump.

By passing the NF concentrated water to the side of the first space 14 and passing the concentrated water of similar concentration to the side of the second space 16, the osmotic pressure generated by the semi-permeable membrane 12 can be reduced, thereby reducing the required pressure. As a result, NF concentrated water can be concentrated to a concentration that cannot be concentrated by the conventional reverse osmosis membrane method.

The inlet pressure of the first space 14 should be set at the range below 7MPa; The inlet pressure of the second space 16 should be set at a pressure smaller than the inlet pressure of the first space 14; The inlet pressure of the second space 16 should be set at the first 50% or less of the inlet pressure of a space 14. In this way, the risk of damage to the semi-permeable membrane due to pressure can be reduced.

It is desirable to make the flow rate on the side of the first space 14 larger than the flow rate on the side of the second space 16 . If the flow rate on the first space 14 side is lower than the flow rate on the second space 16 side, the permeate flux may be too high. For example, the pump 18, the inverter 20, the valve 22, the valve 23, and the valve 32, etc., function as "a flow rate adjustment mechanism that makes the flow rate in the first space larger than the flow rate in the second space".

If the permeate flux is too high, the concentration difference will become larger, the risk of fouling will increase, and problems such as pressure becoming too high may occur. In addition, if the permeate flux is too small, the concentration efficiency may be deteriorated. From these viewpoints, the permeation flux of the membrane module 10 is preferably set in the range of 0.005 m/d to 0.05 m/d, more preferably in the range of 0.015 m/d to 0.04 m/d. In addition, the permeate flux is defined as the permeate flow per unit time and unit membrane area. For example, the pump 18, the frequency converter 20, the valve 22, the valve 23, the valve 32, etc., function as "a permeation flux adjustment mechanism that controls the permeation flux within the above-mentioned range".

In addition, the installation position or number of installation of the valve is only an example, and the number shown in Fig. 1 and Fig. 2 may be greater, and may be installed in at least one of other piping. In addition, a flow measurement mechanism (that is, a flow meter) for measuring a flow rate or a pressure measurement mechanism (that is, a pressure gauge) for measuring a pressure may be provided in at least one of the piping.

In the water treatment method and water treatment device of this embodiment, a multi-stage semi-permeable membrane module can also be used. Examples of water treatment devices with these structures are shown in FIG. 3 , FIG. 4 , and FIG. 5 . The water treatment device shown in Fig. 3, Fig. 4 and Fig. 5 has a structure in which three sections of semi-permeable membrane modules are combined in series.

The water treatment device 3 shown in Fig. 3 is equipped with: a nanofiltration device 11, which is used as a nanofiltration mechanism, and uses a nanofiltration membrane to obtain NF permeated water and NF concentrated water for drainage such as ammonia-containing drainage; and for example, the first The 1st stage film module 10a, the 2nd stage film module 10b, and the 3rd stage film module 10c, as a semipermeable membrane processing mechanism, have a first space (concentrating side) 14 and a second space separated by a semipermeable membrane 12 The second space (permeation side) 16 is connected into a plurality of semi-permeable membrane modules, using these modules, the NF concentrated water of the nanofiltration device 11 flows to the first space 14 of the semi-permeable membrane module of the first stage , the first space 14 is pressurized, and the moisture contained in the NF concentrated water is permeated through the semipermeable membrane 12 to obtain concentrated water, and the concentrated water is obtained from the concentrated water by using the semipermeable membrane module after the next stage, and at the same time, A part of the NF concentrated water or a part of the concentrated water flows into the second space 16 of the semi-permeable membrane module of each stage to obtain dilution water. Each film module has a first space 14 and a second space 16 separated by a semipermeable membrane 12 . The water treatment device 3 may also have: a dilution water tank 60a storing dilution water from the first stage membrane module 10a, a dilution water tank 60b storing dilution water from the second stage membrane module 10b, and a dilution water tank 60b storing dilution water from the third stage film module 10a. The dilution water tank 60c for the dilution water of the module 10c. The membrane module 10 is "supply the NF concentrated water to the first space and the second space of the membrane module of the first stage, and supply the concentrated water to the first space and the second space of the membrane module of the next stage in sequence." Two space, to carry out concentration processing "device. The water treatment device 3 may also be equipped with a NF concentrated water tank for storing NF concentrated water between the nanofiltration device 11 and the membrane module 10 .

In the water treatment device 3 shown in FIG. 3 , a pipe 25 is connected to the inlet of the nanofiltration device 11 through a permeation pump 21 . The pipe 27 was connected to the NF permeated water outlet of the nanofiltration device 11 . The NF concentrated water outlet of the nanofiltration device 11 is connected to the first space inlet of the first-stage membrane module 10 a through a pump 18 through a pipe 40 . A pipe 42 branched from the pipe 40 on the downstream side of the pump 18 is connected to the second space inlet of the membrane module 10a through the valve 22a. The outlet of the second space of the first-stage film module 10 a and the inlet of the dilution water tank 60 a are connected by a pipe 46 . The outlet of the first space of the first-stage film module 10 a and the inlet of the first space of the second-stage film module 10 b are connected by a pipe 44 . The pipe 48 branched from the pipe 44 is connected to the second space inlet of the second-stage film module 10b through the valve 22b. The outlet of the second space of the second-stage film module 10b and the inlet of the dilution tank 60b are connected by a pipe 52 . The outlet of the first space of the second-stage film module 10b and the inlet of the first space of the third-stage film module 10c are connected by a pipe 50 . The pipe 54 branched from the pipe 50 is connected to the second space inlet of the third-stage film module 10c through the valve 22c. The outlet of the second space of the third-stage film module 10c and the inlet of the dilution water tank 60c are connected by a pipe 58 . A pipe 56 is connected to the outlet of the first space of the third-stage film module 10c through the valve 23 . The outlet of the dilution water tank 60 a is connected to the upstream side of the pump 21 in the piping 25 by a piping 59 . The outlet of the dilution tank 60 b is connected to the pipe 59 by a pipe 61 . The outlet of the dilution water tank 60c is connected to the pipe 59 by the pipe 63 .

The membrane module 10 is a multi-stage membrane module having a first space 14 and a second space 16 separated by a semi-permeable membrane 12, and supplies NF concentrated water to the first space of the membrane module of the first stage And the second space, and the concentrated water is supplied to the first space and the second space of the film module of the next section in sequence, and the first space 14 of each section is pressurized, so that the moisture contained in the first space 14 A device that penetrates into the second space 16 through the semi-permeable membrane 12 to concentrate the water. That is, in the membrane module 10 , the NF concentrated water is concentrated by the semipermeable membrane 12 , and the concentrated water is further concentrated by the semipermeable membrane 12 of the next stage.

In the water treatment device 3 , water to be treated, that is, ammonia-containing wastewater containing ammonia, is supplied to the nanofiltration device 11 by the pump 21 through the pipe 25 . In the nanofiltration device 11 , a nanofiltration membrane is used for ammonia-containing wastewater to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

The NF concentrated water obtained in the nanofiltration device 11 is transported to the first space 14a of the first-stage membrane module 10a by the pump 18 through the piping 40 when the valve 23 is opened, and the NF concentrated from the piping 40 The water is sent to the second space 16a of the first-stage film module 10a through the pipe 42 with the valve 22a opened. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. In the first stage of the membrane module 10a, the first space 14a is pressurized, and the moisture contained in the first space 14a permeates through the semi-permeable membrane 12a to the second space 16a [concentration step (first stage)], and at the same time The second space 16a receives dilution water [dilution step (paragraph 1)]. The dilution water obtained in the second space 16a of the first-stage film module 10a is stored in the dilution water tank 60a through the pipe 46 as needed. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipe 59 (return step).

The concentrated water obtained in the first space 14a of the first stage membrane module 10a is delivered to the first space 14b of the second stage membrane module 10b through the pipe 44, and the concentrated water diverted from the pipe 44 is passed through the valve 22b as In the open state, it is sent to the second space 16b of the second-stage film module 10b through the pipe 48 . In the second stage of the membrane module 10b, the first space 14b is pressurized, and the moisture contained in the first space 14b permeates through the semi-permeable membrane 12b to the second space 16b [concentration step (second stage)], and at the same time The second space 16b receives dilution water [dilution step (paragraph 2)]. The dilution water obtained in the second space 16b of the second-stage film module 10b is stored in the dilution water tank 60b through the piping 52 as needed. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipes 61 and 59 (return step).

The concentrated water obtained in the first space 14b of the second stage membrane module 10b is delivered to the first space 14c of the third stage membrane module 10c through the pipe 50, and the concentrated water diverted from the pipe 50 is passed through the valve 22c as In the open state, it is sent to the second space 16c of the third-stage film module 10c through the pipe 54 . In the third section of the membrane module 10c, the first space 14c is pressurized, and the moisture contained in the first space 14c permeates through the semi-permeable membrane 12c to the second space 16c [concentration step (third section)], and at the same time The second space 16c obtains dilution water [dilution step (paragraph 3)] (the above is the semipermeable membrane treatment step). The dilution water obtained in the second space 16c of the film module 10c in the third stage is stored in the dilution water tank 60c through the piping 58 as needed. The concentrated water obtained in the first space 14c of the third-stage membrane module 10c is discharged through the pipe 56 . At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipes 63 and 59 (return step).

Here, the pump 18, the pipes 40, 42, 44, 48, 50, 54, etc., function as the first spaces 14a, 14b of the membrane modules 10a, 10b, 10c that supply NF concentrated water or concentrated water to each stage. , 14c, the supply mechanism of the second space 16a, 16b, 16c" function. The pipes 59, 61, 63, etc. function as "a return mechanism that returns at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second spaces 16a, 16b, 16c of the film modules 10a, 10b, 10c of each section can be discharged out of the system, or can be transported to the dilution water tanks 60a, 60b, 60c for storage as needed, It can also be reused after being discharged out of the system. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a part of the dilution water.

Volume reduction of ammonia-containing wastewater is carried out by recovering concentrated water (concentrated water in the final stage) of at least one of ammonia and ammonium ions from the treatment target (that is, ammonia-containing wastewater containing ammonia) in the above-mentioned manner. deal with. In addition, NF permeated water, concentrated water, and diluted water can be reused.

The water treatment device 4 shown in Fig. 4 is equipped with: a nanofiltration device 11, which is used as a nanofiltration mechanism, and uses a nanofiltration membrane to obtain NF permeated water and NF concentrated water for drainage such as ammonia-containing drainage; and for example, the first The 1st stage film module 10a, the 2nd stage film module 10b, and the 3rd stage film module 10c, as a semipermeable membrane processing mechanism, have a first space (concentrating side) 14 and a second space separated by a semipermeable membrane 12 The second space (permeation side) 16 is connected into a plurality of semi-permeable membrane modules, using these modules, the NF concentrated water of the nanofiltration device 11 flows to the first space 14 of the semi-permeable membrane module of the first stage , the first space 14 is pressurized, and the moisture contained in the NF concentrated water is permeated through the semipermeable membrane 12 to obtain concentrated water, and the concentrated water is obtained from the concentrated water by using the semipermeable membrane module after the next stage, and at the same time, At least a part of the concentrated water flows into the second space 16 of the semi-permeable membrane modules of each stage to obtain dilution water. Each film module has a first space 14 and a second space 16 separated by a semipermeable membrane 12 . The water treatment device 4 may also be provided with: a dilution water tank 62a storing dilution water from the first stage membrane module 10a, a dilution water tank 62b storing dilution water from the second stage membrane module 10b, and a dilution water tank 62b storing the dilution water from the third stage film module 10a; The dilution water tank 62c for the dilution water of the module 10c. The membrane module 10 is "supply NF concentrated water to the first space of the membrane module of the first stage, and supply the concentrated water to the first space of the membrane module of the next stage and its own second space in sequence , to carry out concentration processing "device. The water treatment device 4 may also be equipped with a NF concentrated water tank for storing NF concentrated water between the nanofiltration device 11 and the membrane module 10 .

In the water treatment device 4 shown in FIG. 4 , a pipe 25 is connected to the inlet of the nanofiltration device 11 through a permeation pump 21 . The pipe 27 was connected to the NF permeated water outlet of the nanofiltration device 11 . The NF concentrated water outlet of the nanofiltration device 11 is connected to the first space inlet of the first-stage membrane module 10 a through a pump 18 through a pipe 40 . The outlet of the first space of the first-stage film module 10 a and the inlet of the first space of the second-stage film module 10 b are connected by a pipe 44 . A pipe 64 branched from the pipe 44 is connected to the second space inlet of the film module 10a through the valve 32a. The outlet of the second space of the first-stage film module 10 a and the inlet of the dilution tank 62 a are connected by a pipe 66 . The outlet of the first space of the second-stage film module 10b and the inlet of the first space of the third-stage film module 10c are connected by a pipe 50 . The pipe 68 branched from the pipe 50 is connected to the second space inlet of the film module 10b through the valve 32b. The outlet of the second space of the second-stage film module 10b and the inlet of the dilution water tank 62b are connected by a pipe 70 . A pipe 56 is connected to the outlet of the first space of the third-stage film module 10c through the valve 23 . The pipe 72 branched from the pipe 56 on the upstream side of the valve 23 is connected to the second space inlet of the film module 10c through the valve 32c. The outlet of the second space of the third-stage film module 10c and the inlet of the dilution water tank 62c are connected by a pipe 74 . The outlet of the dilution water tank 62 a is connected to the upstream side of the pump 21 in the piping 25 by a piping 59 . The outlet of the dilution water tank 62 b is connected to the pipe 59 by the pipe 61 . The outlet of the dilution water tank 62c is connected to the pipe 59 by the pipe 63 .

The membrane module 10 is a multi-stage membrane module having a first space 14 and a second space 16 separated by a semi-permeable membrane 12, and supplies NF concentrated water to the first space of the membrane module of the first stage , the concentrated water is sequentially supplied to the first space of the film module of the next stage and its own second space, and the first space 14 of each stage is pressurized, thereby allowing the moisture contained in the first space 14 to permeate The semi-permeable membrane 12 penetrates into the second space 16 to concentrate the water". That is, in the membrane module 10 , the NF concentrated water is concentrated by the semipermeable membrane 12 , and the concentrated water is further concentrated by the semipermeable membrane 12 of the next stage.

In the water treatment device 4 , water to be treated, that is, ammonia-containing wastewater containing ammonia, is supplied to the nanofiltration device 11 by the pump 21 through the pipe 25 . In the nanofiltration device 11 , a nanofiltration membrane is used for ammonia-containing wastewater to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

The NF concentrated water obtained in the nanofiltration device 11 is delivered to the first space 14a of the first-stage membrane module 10a by the pump 18 through the piping 40 when the valve 23 is opened. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. In the first stage of the membrane module 10a, the first space 14a is pressurized, and the moisture contained in the first space 14a permeates through the semi-permeable membrane 12a to the second space 16a [concentration step (first stage)], and at the same time The second space 16a receives dilution water [dilution step (paragraph 1)]. The concentrated water obtained in the first space 14a of the first stage membrane module 10a is delivered to the first space 14b of the second stage membrane module 10b through the pipe 44, and the concentrated water diverted from the pipe 44 is passed through the valve 32a as In the open state, it is sent to the second space 16a of the first-stage film module 10a through the pipe 64 . The dilution water obtained in the second space 16a of the first-stage film module 10a is stored in the dilution water tank 62a through the piping 66 as needed. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipe 59 (return step).

In the second stage of the membrane module 10b, the first space 14b is pressurized, and the moisture contained in the first space 14b permeates through the semi-permeable membrane 12b to the second space 16b [concentration step (second stage)], and at the same time The second space 16b receives dilution water [dilution step (paragraph 2)]. The concentrated water obtained in the first space 14b of the second stage membrane module 10b is delivered to the first space 14c of the third stage membrane module 10c through the piping 50, and the concentrated water diverted from the piping 50 is passed through the valve 32b as In the open state, it is sent to the second space 16b of the second-stage film module 10b through the pipe 68 . The dilution water obtained in the second space 16b of the second-stage film module 10b is stored in the dilution water tank 62b through the piping 70 as needed. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipes 61 and 59 (return step).

In the third section of the membrane module 10c, the first space 14c is pressurized, and the moisture contained in the first space 14c permeates through the semi-permeable membrane 12c to the second space 16c [concentration step (third section)], and at the same time The second space 16c obtains dilution water [dilution step (paragraph 3)] (the above is the semipermeable membrane treatment step). The concentrated water obtained in the first space 14c of the third-stage membrane module 10c is discharged 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 72 with the valve 32c in an open state. The dilution water obtained in the second space 16c of the film module 10c in the third stage is stored in the dilution water tank 62c through the piping 74 as needed. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipes 63 and 59 (return step).

Here, the pump 18, the piping 40, 44, 64, 50, 68, 56, 72, etc. function as the first space 14a of the membrane modules 10a, 10b, 10c that supply NF concentrated water or concentrated water to each stage. , 14b, 14c, the supply mechanism of the second space 16a, 16b, 16c" function. The pipes 59, 61, 63, etc. function as "a return mechanism that returns at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second spaces 16a, 16b, 16c of the film modules 10a, 10b, 10c of each section can be discharged out of the system, or can be transported to the dilution water tanks 62a, 62b, 62c for storage as needed, It can also be reused after being discharged out of the system. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

Volume reduction of ammonia-containing wastewater is carried out by recovering concentrated water (concentrated water in the final stage) of at least one of ammonia and ammonium ions from the treatment target (that is, ammonia-containing wastewater containing ammonia) in the above-mentioned manner. deal with. In addition, NF permeated water, concentrated water, and diluted water can be reused.

When using multi-segment film modules, the flow on the second space side can also be carried out in series. An example of a water treatment device having such a structure is shown in FIG. 5 .

The water treatment device 5 shown in Figure 5 is equipped with: a nanofiltration device 11, which, as a nanofiltration mechanism, uses a nanofiltration membrane for drainage such as ammonia-containing drainage to obtain NF permeated water and NF concentrated water; and for example, the first The 1st stage film module 10a, the 2nd stage film module 10b, and the 3rd stage film module 10c, as a semipermeable membrane processing mechanism, have a first space (concentrating side) 14 and a second space separated by a semipermeable membrane 12 The second space (permeation side) 16 is connected into a plurality of semi-permeable membrane modules, using these modules, the NF concentrated water of the nanofiltration device 11 flows to the first space 14 of the semi-permeable membrane module of the first stage , the first space 14 is pressurized, and the moisture contained in the NF concentrated water is permeated through the semipermeable membrane 12 to obtain concentrated water, and the concentrated water is obtained from the concentrated water by using the semipermeable membrane module after the next stage, and at the same time, At least a part of the concentrated water or at least a part of the dilution water obtained from other semi-permeable membrane modules flows into the second space 16 of the semi-permeable membrane modules of each stage to obtain the dilution water. Each film module has a first space 14 and a second space 16 separated by a semipermeable membrane 12 . The membrane module 10 is "supply NF concentrated water to the first space of the membrane module of the first stage, and sequentially supply the concentrated water to the first space of the membrane module of the next stage to perform concentration treatment" installation. The water treatment device 5 may also be equipped with a NF concentrated water tank for storing NF concentrated water between the nanofiltration device 11 and the membrane module 10 .

In the water treatment device 5 shown in FIG. 5 , a pipe 25 is connected to the inlet of the nanofiltration device 11 through a permeation pump 21 . The pipe 27 was connected to the NF permeated water outlet of the nanofiltration device 11 . The NF concentrated water outlet of the nanofiltration device 11 is connected to the first space inlet of the first-stage membrane module 10 a through a pump 18 through a pipe 40 . The outlet of the first space of the first-stage film module 10 a and the inlet of the first space of the second-stage film module 10 b are connected by a pipe 44 . The outlet of the first space of the second-stage film module 10b and the inlet of the first space of the third-stage film module 10c are connected by a pipe 50 . A pipe 56 is connected to the outlet of the first space of the third-stage film module 10c through the valve 23 . The pipe 76 branched from the pipe 56 on the upstream side of the valve 23 is connected to the second space inlet of the film module 10c through the valve 32 . The outlet of the second space of the third-stage film module 10c and the inlet of the second space of the second-stage film module 10b are connected by a pipe 78 . The outlet of the second space of the second-stage film module 10b and the inlet of the second space of the first-stage film module 10a are connected by a pipe 80 . The outlet of the second space of the first-stage film module 10 a is connected to the upstream side of the pump 21 in the piping 25 by a piping 82 .

The membrane module 10 is a multi-stage membrane module having a first space 14 and a second space 16 separated by a semi-permeable membrane 12, and supplies NF concentrated water to the first space of the membrane module of the first stage , so that the concentrated water is serially circulated to the first space of the membrane module of the next stage, at least a part of the concentrated water of the membrane module of the final stage is supplied to the second space of itself, and the obtained dilution water is connected in series To the second space of the film module in the front section, the first space 14 of each section is pressurized, so that the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12, so that device for concentrating water. That is, in the membrane module 10 , the NF concentrated water is concentrated by the semipermeable membrane 12 , and the concentrated water is further concentrated by the semipermeable membrane 12 of the next stage.

In the water treatment device 5 , water to be treated, that is, ammonia-containing wastewater containing ammonia, is supplied to the nanofiltration device 11 through a pipe 25 by a pump 21 . In the nanofiltration device 11 , a nanofiltration membrane is used for ammonia-containing wastewater to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

The NF concentrated water obtained in the nanofiltration device 11 is delivered to the first space 14a of the first-stage membrane module 10a by the pump 18 through the piping 40 when the valve 23 is opened. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. On the other hand, the dilution water sent through the second space 16c of the third-stage film module 10c and the second space 16b of the second-stage film module 10b described later is sent to the first-stage film module 10a through the pipe 80 The second space 16a. In the first stage of the membrane module 10a, the first space 14a is pressurized, and the moisture contained in the first space 14a permeates through the semi-permeable membrane 12a to the second space 16a [concentration step (first stage)], and at the same time The second space 16a receives dilution water [dilution step (paragraph 1)]. 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 film module 10a is discharged through the pipe 82 . At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 through the pipe 82 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

In the second-stage film module 10b, the dilution water sent through the second space 16c of the third-stage film module 10c described later is sent to the second space 16b of the second-stage film module 10b through the pipe 78 . The first space 14b is pressurized, and the moisture contained in the first space 14b permeates through the semi-permeable membrane 12b to the second space 16b [concentration step (second paragraph)], and at the same time obtains dilution water in the second space 16b [dilution step (paragraph 2)]. 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 film module 10b is sent to the second space 16a of the first-stage film 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 as described below is sent to the second space 16c through the pipes 56 and 76 . The first space 14c is pressurized, and the moisture contained in the first space 14c permeates through the semipermeable membrane 12c to the second space 16c [concentration step (paragraph 3)], and at the same time obtains dilution water in the second space 16c [dilution step (paragraph 3) ] (The above is the semi-permeable membrane treatment step). The concentrated water obtained in the first space 14c of the third-stage membrane module 10c is discharged 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 film module 10c is sent to the second space 16b of the second-stage film module 10b through the pipe 78 .

Here, the pump 18, the pipes 40, 44, 50, 56, 76, 78, 80, etc., function as the first part of the membrane modules 10a, 10b, 10c that supply NF concentrated water, concentrated water, or dilution water to each stage. The function of the supply mechanism of the first space 14a, 14b, 14c, and the second space 16a, 16b, 16c". The piping 82 and the like function as "a return mechanism for returning at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second space 16a of the film module 10a can be discharged out of the system, or can be discharged out of the system after being transported to the dilution water tank for storage as needed, and can also be reused. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

Volume reduction of ammonia-containing wastewater is carried out by recovering concentrated water (concentrated water in the final stage) of at least one of ammonia and ammonium ions from the treatment target (that is, ammonia-containing wastewater containing ammonia) in the above-mentioned manner. deal with. In addition, NF permeated water, concentrated water, and diluted 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. The concentrated water of the module is gradually concentrated, and the concentration is gradually increased. Since the concentration is finally concentrated to a high concentration, by means of this method that can reduce the osmotic pressure, it can be concentrated to a concentration that is difficult to concentrate due to the influence of osmotic pressure in the conventional reverse osmosis membrane method.

When the NF concentrated water is supplied to the first-stage membrane module 10a, for example, a pressure of 7 MPa or less is applied, and the supply of concentrated water to the subsequent membrane module can be carried out by using the pressure applied to the first-stage membrane module 10a. . The inlet pressure of the first space 14 in each film module should be set at the range below 7MPa; The inlet pressure of the second space 16 should be set at a pressure smaller than the inlet pressure of the first space 14; The inlet of the second space 16 The pressure is more preferably set at 50% or less of the inlet pressure of the first space 14 . In this way, the risk of damage to the semi-permeable membrane due to pressure can be reduced.

It is preferable to make the flow on the side of the first space 14 in each film module 10 larger than the flow on the side of the second space 16 . When the flow rate on the side of the first space 14 is lower than the flow rate on the side of the second space 16 , the flow rate on the side of the first space 14 of the subsequent film module may be insufficient. For example, the pump 18, the frequency converter 20, the valves 22a, 22b, 22c, the valve 23, the valves 32a, 32b, 32c, and the valve 32, etc., play a role of "flow regulation to make the flow rate of the first space larger than the flow rate of the second space." organization" function.

If the permeate flux is too large, the concentration polarization on the membrane surface will become larger, the risk of fouling will increase, and problems such as pressure becoming too high may occur. In addition, if the permeate flux is too small, the concentration efficiency may be deteriorated. From these viewpoints, the permeation flux of each membrane module 10 is preferably set in the range of 0.005 m/d to 0.05 m/d, more preferably in the range of 0.015 m/d to 0.04 m/d. For example, the pump 18, the inverter 20, the valves 22a, 22b, 22c, the valve 23, the valves 32a, 32b, 32c, the valve 32, etc., perform the function of "as a permeation flux adjustment mechanism that controls the permeation flux within the above range". .

In addition, the installation positions and number of valves are only examples, and the valves may be more than those shown in Fig. 3, Fig. 4, and Fig. 5, and may be installed in at least one of the other piping. In addition, a flow measurement mechanism (that is, a flow meter) for measuring a flow rate or a pressure measurement mechanism (that is, a pressure gauge) for measuring a pressure may be provided in at least one of the piping.

In addition, Fig. 3, Fig. 4 and Fig. 5 are only an example of the device structure, and the arrangement of the semi-permeable membrane modules and the method of supplying the water supply can also be appropriately changed.

The water treatment device of Fig. 5, because the first space and the second space of the membrane modules of each section are respectively connected in series, compared with the water treatment device of Fig. 3 and Fig. 4, the overall water volume can be suppressed, thereby reducing The power of the pump, so it is a better form.

In the water treatment method and water treatment device of this embodiment, a multi-stage membrane module is used, but as the membrane module of each stage, a membrane module with a plurality of membrane modules connected in parallel can also be used. unit. Examples of water treatment devices with these structures are shown in FIGS. 6 and 7 . The water treatment device shown in Fig. 6 and Fig. 7 has "combination of 4 rows of semi-permeable membrane modules in parallel in the first section, combination of 4 rows of semi-permeable membrane modules in parallel in the 2nd section, and combination of 4 rows of semi-permeable membrane modules in parallel in the 3rd section Combine 2 rows of semi-permeable membrane modules in parallel, combine 2 rows of semi-permeable membrane modules in parallel in the fourth stage, and connect them in series to form a 4-stage structure.

The water treatment device 6 shown in Figure 6 is equipped with: a nanofiltration device 11, which is used as a nanofiltration mechanism to obtain NF permeated water and NF concentrated water by using a nanofiltration membrane for drainage such as ammonia-containing drainage; and for example, the first The 1st section film module unit 100a, the 2nd section film module unit 100b, the 3rd section film module unit 100c, and the 4th section film module unit 100d, which, as a semipermeable membrane processing mechanism, have a semipermeable membrane 12 Separate the first space (concentration side) 14 and the second space (permeation side) 16 and connect them into a plurality of semi-permeable membrane modules. Using these modules, the NF concentrated water of the nanofiltration device 11 can be circulated to the first The first space 14 of the semi-permeable membrane module of the first stage, the first space 14 is pressurized, and the moisture contained in the NF concentrated water permeates through the semi-permeable membrane 12 to obtain concentrated water, from which the concentrated water is used in the next stage. The semi-permeable membrane module obtains concentrated water, and at the same time, a part of the NF concentrated water or a part of the concentrated water is circulated to the second space 16 of the semi-permeable membrane module of each section to obtain dilution water. The first film module unit 100a, for example, has four film modules connected in parallel; the second film module unit 100b, for example, has four film modules connected in parallel; the third film module unit 100c , for example, includes two film modules connected in parallel; the fourth-stage film module unit 100d includes, for example, two film modules connected in parallel. Each thin film module 10 has a first space 14 and a second space 16 separated by a semipermeable membrane 12 . The water treatment device 6 may also include: a NF concentrated water tank 84 for storing NF concentrated 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 "supply the NF concentrated water to the first space and the second space of each membrane module of the membrane module unit of the first stage, and supply the concentrated water to the membrane modules of the next stage sequentially." The first space and the second space of each thin film module of the group unit, so as to carry out the device of concentration treatment.

In the water treatment device 6 shown in FIG. 6 , a pipe 25 is connected to the inlet of the nanofiltration device 11 through a permeation pump 21 . The pipe 27 was connected to the NF permeated water outlet of the nanofiltration device 11 . The outlet of the NF concentrated water of the nanofiltration device 11 and the inlet of the NF concentrated water tank 84 are connected by a pipe 29 . The outlet of the NF concentrated water tank 84 is connected to the inlet of the first space and the inlet of the second space of each membrane module of the first-stage membrane module unit 100 a through the pump 18 through the pipe 88 . The first space outlet of each film module of the first-stage film module unit 100a is connected to the first space inlet and the second space inlet of each film module of the second-stage film module unit 100b by a pipe 90 . The first space outlet of each film module of the second-stage film module unit 100b is connected to the first space inlet and the second space inlet of each film module of the third-stage film module unit 100c by a pipe 94 . The first space outlet of each film module of the third-stage film module unit 100c is connected to the first space inlet and the second space inlet of each film module of the fourth-stage film module unit 100d by a pipe 98 . The outlet of the first space of each membrane module of the fourth-stage membrane module unit 100d and the inlet of the concentrated water tank 86 are connected by a pipe 104 . At the second space outlet of each film module of the first section of film module unit 100a, a piping 92 is connected; at the second space outlet of each film module of the second section of film module unit 100b, a piping 96 is connected; At the second space outlet of each film module of the 3rd section film module unit 100c, the piping 102 is connected; at the second space outlet of each film module of the 4th section film module unit 100d, the piping 106 is connected; The pipes 96 , 102 , 106 may also merge with the pipe 92 . The pipe 92 is connected to the upstream side of the pump 21 in the pipe 25 .

The membrane module unit 100 is "a multistage membrane module unit having a membrane module 10 having a first space 14 and a second space 16 separated by a semipermeable membrane 12, and supplies NF concentrated water to the first stage. The first space and the second space of each film module of the film module unit of the film module unit, the concentrated water is supplied to the first space and the second space of each film module of the film module unit of the next stage in sequence, and each The first space 14 of the film module of the section is pressurized, so that the moisture contained in the first space 14 penetrates through the semi-permeable membrane 12 to the second space 16, so as to concentrate the water". That is, in the membrane module unit 100 , the NF concentrated water is concentrated by the semipermeable membrane 12 , and the concentrated water is concentrated by the semipermeable membrane 12 of the next stage.

In the water treatment device 6 , water to be treated, that is, ammonia-containing wastewater containing ammonia, is supplied to the nanofiltration device 11 through a pipe 25 by a pump 21 . In the nanofiltration device 11 , a nanofiltration membrane is used for ammonia-containing wastewater to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

The NF concentrated water obtained by the nanofiltration device 11, after being stored in the NF concentrated water tank 84 as needed, is transported from the NF concentrated water tank 84 to each part of the first stage membrane module unit 100a through the piping 88 by using the pump 18. The first space 14 and the second space 16 of the film module. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. In each film module of the film module unit 100a of the first stage, the first space 14a is pressurized, and the moisture contained in the first space 14 permeates into the second space 16 through the semi-permeable membrane 12 [concentrating step (first paragraph)], while obtaining dilution water in the second space 16 [dilution step (paragraph 1)]. The dilution water obtained in the second space 16 of the film module 10 in the first stage is stored in the dilution water tank through the pipe 92 as needed and then discharged. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 through the pipe 92 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

The concentrated water obtained in the first space 14 of each film module of the first stage film module unit 100a is delivered to the first space 14 and Second space 16. In each membrane module of the second stage membrane module unit 100b, the first space 14 is pressurized, and the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 [concentrating step (second paragraph)], while obtaining dilution water in the second space 16 [dilution step (paragraph 2)]. The dilution water obtained in the second spaces 16 of the membrane modules of the second-stage membrane module unit 100b is stored in the dilution water tank through the piping 96 as needed and then discharged. At least a part of the dilution water may be returned to the front stage of the nanofiltration device 11 through the pipes 96 and 92 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

The concentrated water obtained in the first space 14 of each membrane module of the second stage membrane module unit 100b is delivered to the first space 14 and the second chamber of each membrane module of the third stage membrane module unit 100c through piping 94. Two spaces16. In each film module of the 3rd stage film module unit 100c, the first space 14 is pressurized, and the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 [concentrating step (3rd step paragraph)], while obtaining dilution water in the second space 16 [dilution step (paragraph 3)]. The dilution water obtained in the second spaces 16 of the membrane modules of the third-stage membrane module unit 100c is stored in the dilution water tank through the piping 102 as needed and then discharged. At least a part of the dilution water may be returned to the front stage of the nanofiltration device 11 through the pipes 102 , 96 , 92 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

The concentrated water obtained in the first space 14 of each film module of the 3rd stage film module unit 100c is delivered to the first space 14 and the first space 14 of each film module of the 4th stage film module unit 100d through piping 98. Two spaces16. In each film module of the 4th stage film module unit 100d, the first space 14 is pressurized, and the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 [concentrating step (4th step paragraph)], and at the same time obtain dilution water in the second space 16 [dilution step (paragraph 4)] (the above is the semipermeable membrane treatment step). 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 through the pipe 104 as needed, and then discharged. The dilution water obtained in the second spaces 16 of the membrane modules of the fourth membrane module unit 100d is stored in the dilution water tank through the piping 106 as needed and then discharged. At least a part of the dilution water may be returned to the front stage of the nanofiltration device 11 through the pipes 106 , 102 , 96 , 92 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

Here, the pump 18, the piping 88, 90, 94, 98, etc., function as "the first function of each membrane module unit 100a, 100b, 100c, 100d that supplies NF concentrated water or concentrated water to each stage." Space 14, the function of the supply mechanism of the second space 16". The pipes 92, 96, 102, 106, etc. function as "a return mechanism that returns at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second spaces 16 of the film modules of the film module units 100a, 100b, 100c, and 100d in each section can be discharged out of the system, or can be discharged after being transported to the dilution tank for storage as needed It can also be reused outside the system. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

Volume reduction of ammonia-containing wastewater is carried out by recovering concentrated water (concentrated water in the final stage) of at least one of ammonia and ammonium ions from the treatment target (that is, ammonia-containing wastewater containing ammonia) in the above-mentioned manner. deal with. In addition, NF permeated water, concentrated water, and diluted water can be reused.

The water treatment device 7 shown in Figure 7 is provided with: a nanofiltration device 11, which, as a nanofiltration mechanism, uses a nanofiltration membrane for drainage such as ammonia-containing drainage to obtain NF permeated water and NF concentrated water; and for example, the first The 1st section film module unit 100a, the 2nd section film module unit 100b, the 3rd section film module unit 100c, and the 4th section film module unit 100d, which, as a semipermeable membrane processing mechanism, have a semipermeable membrane 12 Separate the first space (concentration side) 14 and the second space (permeation side) 16 and connect them into a plurality of semi-permeable membrane modules. Using these modules, the NF concentrated water of the nanofiltration device 11 can be circulated to the first The first space 14 of the semi-permeable membrane module of the first stage, the first space 14 is pressurized, and the moisture contained in the NF concentrated water permeates through the semi-permeable membrane 12 to obtain concentrated water, from which the concentrated water is used in the next stage. The semi-permeable membrane module obtains concentrated water, and at least a part of the concentrated water or at least a part of the diluted water obtained from other semi-permeable membrane modules circulates to the second space 16 of the semi-permeable membrane modules of each section to obtain dilute with water. The first stage film module unit 100a, for example, has four film modules connected in parallel, the second stage film module unit 100b, for example, has four film modules connected in parallel, and the third stage film module unit 100c , for example, includes two film modules connected in parallel, and the fourth-stage film module unit 100d includes, for example, two film modules connected in parallel. Each thin film module 10 has a first space 14 and a second space 16 separated by a semipermeable membrane 12 . The water treatment device 7 may also include: a NF concentrated water tank 84 for storing NF concentrated 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 "supply NF concentrated water to the first space of the membrane module of the first stage, and supply the concentrated water to the first space of the membrane module of the next stage sequentially to perform concentration treatment "installation.

In the water treatment device 7 shown in FIG. 7 , a pipe 25 is connected to the inlet of the nanofiltration device 11 through a permeation pump 21 . The pipe 27 was connected to the NF permeated water outlet of the nanofiltration device 11 . The outlet of the NF concentrated water of the nanofiltration device 11 and the inlet of the NF concentrated water tank 84 are connected by a pipe 29 . The outlet of the NF concentrated water tank 84 is connected to the inlet of the first space of each membrane module of the first-stage membrane module unit 100 a through the pump 18 through the pipe 108 . The first space outlet of each film module of the first-stage film module unit 100 a and the first space inlet of each film module of the second-stage film module unit 100 b are connected by a pipe 110 . The first space outlet of each film module of the second-stage film module unit 100b and the first space inlet of each film module of the third-stage film module unit 100c are connected by a pipe 112 . The first space outlet of each film module of the third-stage film module unit 100c and the first space inlet of each film module of the fourth-stage film module unit 100d are connected by a pipe 114 . The outlet of the first space of each membrane module of the fourth-stage membrane module unit 100d and the inlet of the concentrated water tank 86 are connected by a pipe 116 . A pipe 118 branched from the pipe 116 is connected to the second space inlet of each film module of the fourth-stage film module unit 100d. The outlet of the second space of each film module of the fourth-stage film module unit 100d and the inlet of the second space of each film module of the third-stage film module unit 100c are connected by a pipe 120 . The outlet of the second space of each film module of the third-stage film module unit 100c and the inlet of the second space of each film module of the second-stage film module unit 100b are connected by a pipe 122 . The outlet of the second space of each film module of the second-stage film module unit 100 b and the inlet of the second space of each film module of the first-stage film module unit 100 a are connected by a pipe 124 . The outlet of the second space of each membrane module of the first-stage membrane module unit 100 a is connected to the upstream side of the pump 21 in the pipeline 25 by a pipeline 126 .

The membrane module unit 100 is "a multistage membrane module unit having a membrane module 10 having a first space 14 and a second space 16 separated by a semipermeable membrane 12, and supplies NF concentrated water to the first stage. The first space of each thin film module of the thin film module unit, make this concentrated water flow to the first space of each thin film module of the thin film module unit of the next stage sequentially in series, the thin film module unit of final stage At least a part of the concentrated water of each membrane module is supplied to the second space of itself, so that the obtained dilution water is circulated in series to the second space 16 of each membrane module of the membrane module unit of the previous section, and each section The first space 14 is pressurized, whereby the moisture contained in the first space 14 permeates through the semi-permeable membrane 12 to the second space 16, so as to concentrate the water". That is, in the membrane module unit 100 , the NF concentrated water is concentrated by the semipermeable membrane 12 , and the concentrated water is further concentrated by the semipermeable membrane 12 of the next stage.

In the water treatment device 7 , water to be treated, that is, ammonia-containing wastewater containing ammonia, is supplied to the nanofiltration device 11 through a pipe 25 by a pump 21 . In the nanofiltration device 11 , a nanofiltration membrane is used for ammonia-containing wastewater to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

The NF concentrated water obtained by the nanofiltration device 11, after being stored in the NF concentrated water tank 84 as needed, is transported from the NF concentrated water tank 84 to each part of the first-stage membrane module unit 100a through the piping 108 by using the pump 18. The first space 14 of the film module. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. On the other hand, through the second space 16 of each film module of the fourth stage film module unit 100d described later, the second space 16 of each film module of the third stage film module unit 100c, the second stage film module The dilution water sent from the second space 16 of each film module of the group unit 100b is sent to the second space 16 of each film module of the first-stage film module unit 100a through the pipe 124 . In each film module of the film module unit 100a of the first section, the first space 14 is pressurized, and the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 [concentrating step (first paragraph)], while obtaining dilution water in the second space 16 [dilution step (paragraph 1)]. 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 the pipe 110 . The dilution water obtained in the second space 16 of each membrane module of the first-stage membrane module unit 100 a is discharged through the pipe 126 . At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 through the pipe 126 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

In each film module of the 2nd stage film module unit 100b, through the second space 16 of each film module of the 4th stage film module unit 100d described later, each film mold of the 3rd stage film module unit 100c The dilution water sent from the second space 16 of the group is sent to the second space 16 of each film module of the second-stage film module unit 100 b through the pipe 122 . The first space 14 is pressurized, and the water contained in the first space 14 permeates through the semi-permeable membrane 12 to the second space 16 [concentration step (second paragraph)], and at the same time obtains dilution water in the second space 16 [dilution step (paragraph 2)]. 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 film module of the second-stage film module unit 100b is sent to the second space 16 of each film module of the first-stage film module unit 100a through the pipe 124 .

In each film module of the 3rd stage film module unit 100c, the dilution water conveyed through the second space 16 of each film module of the 4th stage film module unit 100d described later is sent to the 3rd stage through the pipe 120. The second space 16 of each film module of the section film module unit 100c. The first space 14 is pressurized, and the moisture contained in the first space 14 permeates through the semipermeable membrane 12 to the second space 16 [concentration step (3rd paragraph)], and at the same time obtains dilution water in the second space 16 [dilution step (paragraph 3)]. The concentrated water obtained in the first space 14 of each membrane module of the third-stage membrane module unit 100c is sent to the first space 14 of each membrane module of the fourth-stage membrane module unit 100d through a pipe 114 . The dilution water obtained in the second space 16 of each film module of the third-stage film module unit 100c is sent to the second space 16 of each film module of the second-stage film module unit 100b through the pipe 122 .

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 as described below passes through pipes 116, 118 Transported to the second space 16. The first space 14 is pressurized, and the moisture contained in the first space 14 permeates through the semi-permeable membrane 12 to the second space 16 [concentration step (paragraph 4)], and at the same time obtains dilution water in the second space 16 [dilution step (paragraph 4)] (the above is the semi-permeable membrane treatment step). 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 through the pipe 116 as needed and then discharged. The concentrated water branched 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 film module of the fourth-stage film module unit 100d is sent to the second space 16 of each film module of the third-stage film module unit 100c through the pipe 120 .

Here, the pump 18, piping 108, 110, 112, 114, 116, 118, 120, 122, 124, etc., function as "the membrane module unit 100a, which supplies NF concentrated water, concentrated water, or dilution water to each stage. 100b, 100c, 100d the function of the "supply mechanism" of the first space 14 and the second space 16 of each film module. The piping 126 and the like function as "a return mechanism for returning at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second space 16 of each film module of the film module unit 100a can be discharged out of the system, and can also be discharged out of the system after being transported to the dilution tank for storage according to needs, and can also be reused. . At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

Volume reduction of ammonia-containing wastewater is carried out by recovering concentrated water (concentrated water in the final stage) of at least one of ammonia and ammonium ions from the treatment target (that is, ammonia-containing wastewater containing ammonia) in the above-mentioned manner. deal with. In addition, NF permeated water, concentrated water, and diluted water can be reused.

When the NF concentrated water is supplied to each membrane module of the first-stage membrane module unit 100a, for example, a pressure of 7 MPa or less is applied, and the supply of concentrated water to the membrane module unit of the rear stage only needs to be performed by using the first-stage membrane module unit The pressure applied by each film module of 100a can be implemented. The inlet pressure of the first space 14 in each film module should be set at the range below 7MPa; The inlet pressure of the second space 16 should be set at a pressure smaller than the inlet pressure of the first space 14; The inlet of the second space 16 The pressure is more preferably set at 50% or less of the inlet pressure of the first space 14 . In this way, the risk of damage to the semi-permeable membrane due to pressure can be reduced.

It is preferable to make the flow on the side of the first space 14 in each film module 10 larger than the flow on the side of the second space 16 . When the flow rate on the side of the first space 14 is lower than the flow rate on the side of the second space 16 , the flow rate on the side of the first space 14 of the subsequent film module may be insufficient. For example, the pump 18 and the like function as "a flow rate adjustment mechanism that makes the flow rate in the first space larger than the flow rate in the second space".

If the permeate flux is too high, the concentration difference will become larger, the risk of fouling will increase, and problems such as pressure becoming too high may occur. In addition, if the permeate flux is too small, the concentration efficiency may be deteriorated. From these viewpoints, the permeation flux of each membrane module 10 is preferably set in the range of 0.005 m/d to 0.05 m/d, more preferably in the range of 0.015 m/d to 0.04 m/d. For example, the pump 18 and the like function as "a permeation flux adjustment mechanism that controls the permeation flux to the above-mentioned range".

In addition, a valve may be provided in at least one of each piping, and the installation position and number of valves are not particularly limited. In addition, a flow measurement mechanism (that is, a flow meter) for measuring a flow rate or a pressure measurement mechanism (that is, a pressure gauge) for measuring a pressure may be provided in at least one of the piping.

In addition, Fig. 6 and Fig. 7 are only an example of the device structure, and the number of stages, the number of parallel connections, the arrangement of the semi-permeable membrane modules, and the method of supplying water can also be appropriately changed.

In order to concentrate the substances to be recovered in the NF concentrated water to a better concentration in the membrane module, the membrane module should be connected in series to form a plurality of sections. When a multi-stage membrane module is used as in the water treatment devices 3, 4, 5, 6, and 7, the number of stages of the membrane module may be determined according to the target treatment water concentration and the like. For example, when it is desired to obtain high-concentration treated water from low-concentration NF concentrated water, it is only necessary to increase the number of stages of the membrane module unit.

When like water treatment device 6,7, when using the film module unit that possesses the plurality of film modules connected in parallel as the film module of each stage, the number of the film modules in each film module unit, as long as according to The flow rate of NF concentrated water and the like may be determined.

Concentration water tanks or dilution water tanks can also be installed in more than one stage of the membrane module, and concentration water tanks or dilution water tanks can also be installed in the membrane modules of each stage.

The water to be treated, that is, drainage, is, for example, drainage from factories, etc., but is not particularly limited. Drainage is, for example, ammonium ion-containing drainage, sulfate ion and ammonium ion-containing drainage, sulfuric acid ion, ammonium ion, and silicon dioxide-containing ammonia-containing wastewater, such as wastewater discharged from a semiconductor factory, from Drainage from chemical factories, etc. In particular, in semiconductor factories, ammonia is used for cleaning of wafers, etc., and sulfuric acid is used for cleaning treatment of ammonia. Therefore, ammonium ions and sulfate ions will be contained in the wastewater. As for the method of recovering ammonia and sulfuric acid in the waste water, in general, an evaporation method such as an evaporator or thin film distillation is used, but by installing the water treatment device of this embodiment in the front stage of the evaporator or thin film distillation device, and By supplying the concentrated water from the semi-permeable membrane module to the evaporator or thin-film distillation device, the amount of treated water in the evaporator or thin-film distillation device can be reduced, so the load can be reduced, and ammonia or sulfuric acid can be recovered efficiently.

Before being transported to the nanofiltration device 11 (if equipped with a pretreatment mechanism, it is after the pretreatment and before being transported to the nanofiltration device 11), may also contain monovalent ions and divalent ions at a certain concentration Such ionic components, or contain non-charged species. The drainage, for example, is ammonia-containing drainage containing more than 2,000 mg/L of ammonium ions; ammonia-containing drainage contains 2,000 to 100,000 mg/L of ammonium ions, which is a preferable aspect. Ammonia-containing wastewater, moreover, for example, may also contain more than 6000 mg/L of sulfate ions, and contain more than 5 mg/L of silicon dioxide as a non-charged substance; contain 20000-250000 mg/L of sulfate ions, and contain 5-50 Silicon dioxide of L is a preferable form as a non-charged substance.

The nanofiltration device 11 is not particularly limited as long as it can use a nanofiltration membrane (NF membrane) for drainage to obtain NF permeated water and NF concentrated water.

Here, the nanofiltration membrane refers to a membrane that "filters an aqueous NaCl solution with a concentration of 2000 mg/L under the conditions of an operating pressure of 1.5 MPa and 25°C, with a NaCl rejection rate of 10% to 70%". The material of the film is not particularly limited, and examples thereof include cellulose resins such as cellulose acetate resins, polyether resins such as polyether resins, and polyamide resins. The shape of the film is not particularly limited, but examples thereof include a spiral shape, a hollow line shape, and the like. The primary side pressure during operation is preferably in the range of 0.5 MPa to 10 MPa.

The nanofiltration membrane should be "under the conditions of effective pressure on the membrane surface of 1Mpa, 25°C, and pH 7, the blocking rate of silicon dioxide is in the range of 0-20%, and the blocking rate of ammonium ion and sulfuric acid ion is 90%- The thin film in the range of 100% is more preferably a thin film in which the blocking ratio of silicon dioxide is in the range of 5-18%, and the blocking ratio of ammonium ion and sulfuric acid ion is in the range of 97%-100%. When the silica blocking rate of the nanofiltration membrane exceeds 20%, if the ammoniacal wastewater contains silica, the risk of silica scale precipitation in the membrane module 10 may increase. When the ammonium ion blocking rate and the sulfuric acid ion blocking rate of the nanofiltration membrane are less than 90%, the recovery rate of ammonia and sulfuric acid may be reduced.

Here, the blocking rate of each component of silicon dioxide, ammonium ion, and sulfate ion used to determine the characteristics of the nanofiltration membrane can be obtained by the following formula. Rejection rate (%)=100-100×{[A/((B+C)/2)]} A: Ion concentration of each component in permeate water (mg/L) B: Ion concentration of each component in supply water (mg /L) C: The ion concentration of each component in the concentrated water (mg/L) It is used to determine the water supply and nanofiltration membrane treatment conditions of the silicon dioxide, ammonium ion, and sulfate ion blocking rate of the above-mentioned nanofiltration membrane, such as described below. Water supply: an aqueous solution containing 16500mg/L of ammonium sulfate and 20mg/L of silicon dioxide. Nanofiltration membrane treatment conditions: water temperature 25°C, permeation flux 0.4m ³ /m ² /d, recovery rate 15%. Here, recovery rate (%)=100×[amount of permeated water in nanofiltration membrane treatment (m ³ /h)]/[amount of water supplied to nanofiltration membrane treatment (m ³ /h).

Regarding the semi-permeable membrane 12 of the membrane module, for example, reverse osmosis membrane (RO membrane, Reverse Osmosis Membrane), forward osmosis membrane (FO membrane, Forward Osmosis Membrane), nanofiltration membrane (NF membrane, Nano Filtration Membrane) and other semi-permeable membranes. 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 thereof include cellulose-based resins such as cellulose acetate-based resins, polyether-based resins such as polyether-based resins, and polyamide-based resins. .

As for the shape of the semipermeable membrane 12, a flat membrane, a hollow fiber membrane, a spiral membrane, etc. are mentioned. From the viewpoint of the advantage of increasing the surface area of the semipermeable membrane, the hollow fiber membrane is a preferable aspect.

The recovered product recovered from the concentrated water is at least one of the ammonia and ammonium ions contained in the NF concentrated water, and then it is a dissolved solid component (TDS, Total Dissolved Solid, total dissolved solid). Regarding the dissolved solid component, it can be listed For example: sodium sulfate, calcium sulfate, sodium chloride, calcium chloride and other inorganic salts.

The water treatment method and water treatment device of this embodiment can also include, for example, the use of precision filtration membranes (MF membranes, microfiltration membranes), ultrafiltration membranes (UF membranes) in the front stage of the nanofiltration step (nanofiltration mechanism). , ultrafiltration membrane) and other membrane treatment steps (thin film treatment mechanism), reverse osmosis membrane treatment step (reverse osmosis membrane treatment mechanism), coagulation precipitation treatment step (coagulation precipitation treatment mechanism), organic matter removal treatment step (organic matter removal treatment mechanism), At least one pretreatment step (pretreatment mechanism) among the pH adjustment step (pH adjustment mechanism) and the temperature adjustment step (temperature adjustment mechanism).

When suspended matter is contained, pretreatments such as coagulation and sedimentation, membrane separation, pressurized flotation, etc. can also be performed in the front stage of the nanofiltration step (nanofiltration device 11).

It is also possible to perform pH adjustment or temperature adjustment of wastewater in the preceding stage of the nanofiltration step (nanofiltration device 11 ). An example of a water treatment device having such a structure is shown in FIG. 8 .

The water treatment device 8 of Fig. 8, for example, in addition to the structure of the water treatment device 2 of Fig. 2, also can be equipped with: a pH adjustment device 13, which is used as a pH adjustment mechanism, in the nanofiltration step (nanofiltration device 11 ) to adjust the pH of the drainage; and the temperature adjustment device 15 as a temperature adjustment mechanism to adjust the temperature of the drainage.

In the water treatment device 8 shown in FIG. 8 , a pipe 31 is connected to the inlet of the pH adjustment device 13 . The outlet of the pH adjustment device 13 and the inlet of the temperature adjustment device 15 are connected by a pipe 33 . The outlet of the temperature adjustment device 15 and the inlet of the nanofiltration device 11 are connected by a pipe 25 through a pump 21 . The connection order of the pH adjustment device 13 and the temperature adjustment device 15 may also be reversed. The other structures are the same as those of the water treatment device 2 in FIG. 2 . In the water treatment apparatuses 1 and 3 to 7 shown in FIG. 1 and FIGS. 3 to 7 , a pH adjustment device 13 and a temperature adjustment device 15 may be provided.

In the water treatment device 8 , water to be treated, ie, ammonia-containing wastewater containing ammonia, is sent to the pH adjustment device 13 through the pipe 31 . In the pH adjustment device 13 , pH adjustment of ammonia-containing wastewater is performed (pH adjustment step). The ammonia-containing wastewater subjected to pH adjustment is sent to the temperature adjustment device 15 through the pipe 33 . In the temperature adjustment device 15 , temperature adjustment of ammonia-containing wastewater is performed (temperature adjustment step). The connection sequence of the pH adjustment device 13 and the temperature adjustment device 15 can also be reversed, and after the temperature adjustment of the ammonia-containing wastewater (temperature adjustment step), the pH adjustment of the ammonia-containing wastewater whose temperature has been adjusted (pH adjustment step) can also be implemented. ).

The ammonia-containing wastewater subjected to pH adjustment and temperature adjustment is supplied to the nanofiltration device 11 through the pipe 25 by the pump 21 . Afterwards, the nanofiltration step and the semipermeable membrane treatment step are performed similarly to the water treatment device 2 in FIG. 2 . For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used.

In the above manner, at least one of ammonia and ammonium ions is recovered from the treatment object (that is, ammonia-containing wastewater containing ammonia) as concentrated water, and volume reduction treatment of ammonia-containing wastewater is performed. In addition, NF permeated water, concentrated water, and diluted water can be reused.

The pH adjusting device 13 includes, for example, a pH adjusting agent adding mechanism such as a pH adjusting agent adding pipe, a pH measuring device, a pH adjusting tank, and the like. A pH regulator is added to the pH adjustment tank to adjust the pH of the drainage to a range of pH 4 to 8, more preferably to a range of pH 4 to 7, which is a better aspect. If the pH of the wastewater is less than 4, when the wastewater contains ammonia, the ammonium ion blocking rate of the nanofiltration membrane may decrease; if the pH exceeds 8, when the wastewater contains ammonia, the ammonia will start to gasify and permeate through the nanofiltration membrane, so the concentration efficiency of ammonia may be reduced. pH adjustment may be performed in components such as piping without providing a pH adjustment tank.

Examples of the pH adjuster include acids such as hydrochloric acid and sulfuric acid, and alkalis such as sodium hydroxide.

The temperature adjustment device 15 includes, for example, a temperature adjustment tank, a heating device such as a heater, a cooling device such as a cooler, a heat exchanger, a heat pump, and the like. It is advisable to adjust the temperature of the drainage to a range of 20°C to 35°C. In order to suppress the precipitation of silica scale when the drainage contains silica, it is more preferable to adjust it to a range of 25 to 35°C. If the temperature of the drainage is lower than 20°C, when the drainage contains silica, the precipitation concentration of silica may decrease. If it exceeds 35°C, the blocking efficiency of the nanofiltration membrane and semi-permeable membrane may decrease.

It is also possible to perform pH adjustment and temperature adjustment again at the rear stage of the nanofiltration device 11 and before passing through the semi-permeable membrane module. The pH and water temperature when flowing to the semi-permeable membrane module can be determined according to the quality of the drainage water and the material of the semi-permeable membrane module. For example, it is preferable to set the pH of the drainage in the range of 4 to 8, and to set the water temperature in the range of 20°C to 35°C.

For pH adjustment, for example, a pH adjustment tank is provided, and a pH adjuster is added to the pH adjustment tank to adjust pH.

For water temperature adjustment, for example, a water temperature adjustment tank may be provided, and a heating device such as a heater may be used for heating in the water temperature adjustment tank, or a heat exchanger may be provided for adjustment.

The schematic structure of another example of the water treatment apparatus which concerns on embodiment of this invention is shown in FIG. 9, and it demonstrates about this structure.

The water treatment device 9 shown in FIG. 9 is a device for concentrating the water to be treated (ammonia-containing wastewater) containing ammonia and silicon dioxide. The water treatment device 9 is equipped with: a pH adjustment device 13, which, as a pH adjustment mechanism, adjusts the pH of the water to be treated to a range of 7 to 9; and a nanofiltration device 11, which, as a nanofiltration mechanism, adjusts the The treated water uses nanofiltration membranes to obtain NF permeate water and NF concentrated water. The water treatment device 9 may also be equipped with: for example, a thin film module 10, which is used as a semipermeable membrane treatment mechanism and has a first space (concentrating side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12. The semi-permeable membrane module allows the NF concentrated water from the nanofiltration device 11 to flow into the first space 14, pressurizes the first space 14, and makes the moisture contained in the NF concentrated water permeate through the semi-permeable membrane 12 to obtain concentrated water. A part of the NF concentrated water is circulated to the second space 16 to obtain dilution water. The water treatment device 9 may also be equipped with a NF concentrated water tank for storing NF concentrated water between the nanofiltration device 11 and the membrane module 10 . The water treatment device 9 may also include: an ammonia treatment device 35 , which is used as an ammonia treatment mechanism for treating the ammonia gas discharged from the nanofiltration device 11 .

In the water treatment device 9 shown in FIG. 9 , a pipe 31 is connected to the inlet of the pH adjustment device 13 . The outlet of the pH adjusting device 13 and the inlet of the nanofiltration device 11 are connected by a pipe 25 through a pump 21 . The NF permeated water outlet of the nanofiltration device 11 and the inlet of the ammonia treatment device 35 are connected by a pipe 27 . A pipe 37 is connected to the outlet of the ammonia treatment device 35 . The NF concentrated water outlet of the nanofiltration device 11 is connected to the first space inlet of the membrane module 10 through the pump 18 by the pipe 24, and the pipe 26 branched from the pipe 24 on the downstream side of the pump 18 is connected to the membrane through the valve 22. The entrance to the second space of the module 10. The outlet of the first space of the film module 10 is connected to the pipe 28 through the valve 23 , and the outlet of the second space of the film module 10 is connected to the upstream side of the pump 21 in the pipe 25 through the pipe 30 .

The pump 18 is, for example, a booster pump that "drives at a rotational speed corresponding to the input drive frequency, sucks in NF concentrated water, and discharges it to the membrane module 10 under pressure". The pump 18 is provided with, for example, an inverter 20 that outputs a driving frequency corresponding to an input command signal to the pump 18 . The pump 21 is, for example, a booster pump that "drives at a rotational speed corresponding to the input drive frequency, sucks in the water to be treated, pressurizes it, and discharges it to the nanofiltration device 11". The valve 22 and the valve 23 are, for example, valves that can manually or automatically adjust the degree of opening and closing.

Membrane module 10, "has a first space 14 and a second space 16 separated by a semi-permeable membrane 12, so that NF concentrated water flows from the entrance of the first space of the membrane module 10 to the first space 14, and from the second The entrance of the space flows into the second space 16 to pressurize the first space 14, so that the moisture contained in the NF concentrated water in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 to concentrate the water. installation. That is, in the water treatment device 9 , the NF concentrated water is concentrated by the semipermeable membrane 12 . The thin film module 10 is a device that "supplies NF concentrated water to both the first space 14 and the second space 16 of the thin film module 10 to perform concentration treatment".

In the water treatment device 9 , the water to be treated (ammonia-containing wastewater) containing ammonia and silica is sent to the pH adjustment device 13 through the pipe 31 . In the pH adjustment device 13 , pH adjustment of the water to be treated is carried out (pH adjustment step). The water to be treated adjusted to a pH range of 7 to 9 by performing pH adjustment is supplied to the nanofiltration device 11 through a pipe 25 by a pump 21 . In the nanofiltration device 11 , a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 . The NF permeated water can be discharged out of the system, or discharged into rivers, etc., and advanced water treatment methods can be further set up to recycle the water.

In the pH adjustment step, the pH of the water to be treated is adjusted to a range of pH 7-9. By adjusting the pH of the water to be treated to a pH range of 7-9, ammonia and silicon dioxide will permeate through the nanofiltration membrane, and most of the ammonia and silicon dioxide will be contained in the NF permeated water. In addition, we believe that silicon dioxide is only an example, and if it is a non-charged component, even other components will permeate through the nanofiltration membrane. At this time, if the pH is lower than 7, the permeability of the nanofiltration membrane of ammonia and silicon dioxide may decrease. If the pH exceeds 9, the silicon dioxide will be ionized, and the permeability of silicon dioxide may decrease due to the influence of charge repulsion. .

When the pH of the water to be treated is adjusted to a range of 8 to 9 in the pH adjustment step, ammonia in the water to be treated is gasified. At this time, the water to be treated that has been adjusted to a pH range of 8 to 9 through pH adjustment is supplied to the nanofiltration device 11. In the nanofiltration device 11, a nanofiltration membrane is used for the water to be treated to obtain NF permeation. Water and NF concentrated water (nanofiltration step); NF permeated water is transported to ammonia treatment device 35 through piping 27, and in ammonia treatment device 35, the ammonia gas discharged in the nanofiltration step is processed to obtain treated water (ammonia processing steps). In the ammonia treatment step, the ammonia gas is recovered from the NF permeated water, or the ammonia gas is decomposed.

It is also possible to use a semi-permeable membrane for the NF concentrated water obtained in the nanofiltration device 11 to perform semi-permeable membrane treatment. The NF concentrated water obtained in the nanofiltration device 11 is pressurized and delivered to the first space 14 from the inlet of the first space of the membrane module 10 through the piping 24 by the pump 18 when the valve 23 is opened. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. In addition, the NF concentrated water is sent from the inlet of the second space of the membrane module 10 to flow into the second space 16 through the pipe 26 branched from the pipe 24 with the valve 22 open. Part of the moisture contained in the pressurized NF concentrated water permeates from the first space 14 to the second space 16 through the semipermeable membrane 12 . At this time, since most of the ions contained in the NF concentrated water cannot permeate the semipermeable membrane 12, the water in the first space 14 that has not permeated the semipermeable membrane 12 is concentrated. On the other hand, in the second space 16, a part of the NF concentrated water flowing through the pipe 26 merges with the permeated water having a low ion concentration that has permeated the semipermeable membrane 12, thereby exhibiting a dilution effect. The concentrated water obtained in the first space 14 is discharged from the outlet of the first space through the pipe 28; the diluted water obtained in the second space 16 is discharged from the outlet of the second space through the pipe 30; at least a part of the diluted water can also be sent to Return to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the piping 25 (return step). Here, in the membrane module 10, the first space 14 is pressurized and the moisture contained in the NF concentrated water in the first space 14 permeates through the semipermeable membrane 12 to the second space 16, and then in the first space 14 Concentrated water is obtained (concentration step), while dilution water is obtained in the second space 16 (dilution step) (the above is the semipermeable membrane treatment step).

Here, the pipes 24 , 26 , the pump 18 and the like function as “a supply mechanism for supplying NF concentrated water to both the first space 14 and the second space 16 of the membrane module 10 ”. The piping 30 and the like function as "a return mechanism for returning at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second space 16 can be discharged out of the system through the pipe 30, and can also be discharged out of the system after being transported to the dilution water tank for storage as needed, and can also be reused. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

In the above-mentioned manner, the concentrated water with reduced ammonia and silica content is recovered from the treated water containing the treatment target (namely, ammonia and silica), and the volume reduction treatment of the treated water is carried out. In addition, NF permeated water, concentrated water, and diluted water can be reused.

Alternatively, in the above-mentioned manner, the volume reduction treatment of the treated water is carried out by recovering the ammonia-concentrated water in which the silica is reduced from the treated water containing the treatment object (that is, ammonia and silica).

By making the NF concentrated water flow into 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 semi-permeable membrane 12 can be reduced, and further Concentrate high-concentration ions in NF concentrated water with less energy consumption. That is, NF concentrated water containing high-concentration ions can be concentrated at low cost, and the amount of waste liquid with high ion concentration can be reduced.

Sometimes, due to the scale components contained in the water to be treated, such as wastewater discharged from semiconductor factories, etc., when highly concentrated by semi-permeable membrane treatment, the permeable membrane will be blocked and the concentration will be difficult. In particular, when the water to be treated contains silicon dioxide (SiO ₂ ), it is advisable to remove the silicon dioxide by pre-treatment with a semi-permeable membrane. However, if the concentration of silicon dioxide is too high, sometimes it is difficult to use a dispersant, etc. Potions respond to these problems.

In the water treatment device and water treatment method of this embodiment, even if the water to be treated contains silicon dioxide, the nanofiltration device 11 can still be used to selectively permeate the silicon dioxide in the water to be treated through the nanofiltration membrane , and by making the NF concentrated water whose silicon dioxide concentration has been reduced flow to the first space 14 of the membrane module 10 or both sides of the first space 14 and the second space 16, the object to be concentrated can be highly concentrated stably substance.

At least a part of the dilution water obtained in the second space 16 is sent back to the front section of the nanofiltration device 11, which is a preferred form; A better way: 70-100% of the dilution water is sent back to the front section of the nanofiltration device 11, which is the best way. By circulating the dilution water discharged from the membrane module 10 above a predetermined amount back to the front stage of the nanofiltration device 11, even if silicon dioxide is contained in the treated water, the amount of treated water supplied to the nanofiltration device 11 can be reduced. The ratio of the concentration of silica to the concentration of ammonium ions in the water reduces the risk of silica scaling in the concentration step of semi-permeable membrane treatment.

Regarding the adjustment method for adjusting the supply flow rate of NF concentrated water to the membrane module 10, the flow rate of permeate water, and the flow rate of concentrated water, for example, the following method may be implemented.

An inverter 20 for controlling the driving frequency is installed on the pump 18 to adjust the supply flow rate of NF concentrated water to the membrane module 10 . It is preferable to install the frequency converter 20 on the pump 18, but it is not necessary to install it. As long as "the NF concentrated water is supplied to both the first space 14 side and the second space 16 side, a valve 22 is set before the entrance of the second space 16, and a valve 23 is set at the exit of the first space 14 to manually or automatically adjust the valve. 22 and the opening of the valve 23 to adjust the ratio of the water supply flow to the first space 14 side to the water supply flow to the second space 16 side.

When the permeate water flow rate and concentrated water flow rate are insufficient, it is sufficient to increase the frequency of the frequency converter 20 of the pump 18 to increase the supply of NF concentrated water.

An adjustable opening and closing valve 23 is provided at the outlet of the first space 14 of the piping 28 , and the flow of concentrated water or the pressure at the entrance of the first space 14 and the outlet of the first space 14 can be adjusted by using the opening of the valve 23 .

Through these operations, the pressure and various flow rates on the side of the first space 14 can be adjusted to a predetermined value.

In addition, the NF concentrated water may be supplied to the first space 14 side and the second space 16 side by separate pumps. When supplying NF concentrated water with separate pumps, it is also possible to install an inverter to control the drive frequency for each pump.

By passing the NF concentrated water with the same or similar concentration to both the side of the first space 14 and the side of the second space 16, the osmotic pressure generated by the semipermeable membrane 12 can be reduced, thereby reducing the necessary pressure. As a result, NF concentrated water can be concentrated to a concentration that cannot be concentrated by the conventional reverse osmosis membrane method.

In this way, the treated water containing ammonia and silica can reduce the concentration of silica and concentrate it. In addition, valuable substances can be recovered in high concentration from the water to be treated. Even if the water to be treated contains silica, by performing semi-permeable membrane treatment on NF concentrated water whose silica concentration has been reduced, the risk of silica scale precipitation in the concentration step of semi-permeable membrane treatment can be reduced.

The schematic structure of another example of the water treatment apparatus which concerns on embodiment of this invention is shown in FIG. 10, and it demonstrates about this structure.

The water treatment device 10 shown in Figure 10 is equipped with: a pH adjustment device 13, which is used as a pH adjustment mechanism to adjust the pH of the water to be treated to a range of 7 to 9; and a nanofiltration device 11, which is used as a nanofiltration mechanism. , use nanofiltration membrane for the treated water with adjusted pH to obtain NF permeate water and NF concentrated water. The water treatment device 10 may also be equipped with: for example, a thin film module 10, which is used as a semipermeable membrane treatment mechanism and has a first space (concentration side) 14 and a second space (permeation side) 16 separated by a semipermeable membrane 12. The semi-permeable membrane module allows the NF concentrated water from the nanofiltration device 11 to flow into the first space 14, pressurizes the first space 14, and makes the moisture contained in the NF concentrated water permeate through the semi-permeable membrane 12 to obtain concentrated water. At least a part of the concentrated water is circulated to the second space 16 to obtain dilution water. The water treatment device 10 may also be provided with a NF concentrated water tank for storing NF concentrated water between the nanofiltration device 11 and the membrane module 10 . The water treatment device 10 may also include: an ammonia treatment device 35 , which is used as an ammonia treatment mechanism for treating the ammonia gas discharged from the nanofiltration device 11 .

In the water treatment device 10 of FIG. 10 , a pipe 31 is connected to the inlet of the pH adjustment device 13 . The outlet of the pH adjusting device 13 and the inlet of the nanofiltration device 11 are connected by a pipe 25 through a pump 21 . The NF permeated water outlet of the nanofiltration device 11 and the inlet of the ammonia treatment device 35 are connected by a pipe 27 . A pipe 37 is connected to the outlet of the ammonia treatment device 35 . The NF concentrated water outlet of the nanofiltration device 11 is connected to the first space inlet of the membrane module 10 through a pump 18 through a pipe 24 . A pipe 28 is connected to the outlet of the first space of the film module 10 through a valve 23 . A pipe 34 branched from the pipe 28 on the upstream side of the valve 23 is connected to the second space inlet of the film module 10 through the valve 32 . The outlet of the second space of the thin film module 10 is connected to the upstream side of the pump 21 in the piping 25 through the piping 36 .

The pump 18 is, for example, a booster pump that "drives at a rotational speed corresponding to the input drive frequency, sucks in NF concentrated water, pressurizes it, and discharges it to the membrane module 10". The pump 18 is provided with, for example, an inverter 20 that outputs a driving frequency corresponding to an input command signal to the pump 18 . The pump 21 is, for example, a booster pump that "drives at a rotational speed corresponding to the input drive frequency, sucks in the water to be treated, pressurizes it, and discharges it to the nanofiltration device 11". The valve 23 and the valve 32 are, for example, valves that can manually or automatically adjust the degree of opening and closing.

The thin film module 10 is "having a first space 14 and a second space 16 separated by a semi-permeable membrane 12, so that NF concentrated water flows from the first space entrance of the thin film module 10 to the first space 14, and at the same time makes the thin film module At least a part of the concentrated water discharged from the first space outlet of the first space 14 of the group 10 flows from the second space inlet of the membrane module 10 to the second space 16, pressurizing the first space 14, thereby making the second space 16 The moisture contained in the NF concentrated water in the first space 14 permeates through the semi-permeable membrane 12 to the second space 16 to concentrate the water. That is, in the water treatment device 10 , the NF concentrated water is concentrated by the semipermeable membrane 12 . The thin film module 10 is "supply NF concentrated water to the first space 14 of the thin film module 10, supply at least a part of the concentrated water obtained from the outlet of the first space 14 to the second space 16 of the thin film module 10, To carry out concentration processing "device.

In the water treatment device 10 , the water to be treated (ammonia-containing wastewater) containing ammonia and silica is sent to the pH adjustment device 13 through the pipe 31 . In the pH adjustment device 13 , pH adjustment of the water to be treated is carried out (pH adjustment step). The water to be treated adjusted to a pH range of 7 to 9 by performing pH adjustment is supplied to the nanofiltration device 11 through a pipe 25 by a pump 21 . In the nanofiltration device 11 , a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

In the pH adjustment step, the pH of the water to be treated is adjusted to a range of pH 7-9. By adjusting the pH of the water to be treated to a pH range of 7-9, ammonia and silicon dioxide will permeate through the nanofiltration membrane, and most of the ammonia and silicon dioxide will be contained in the NF permeated water. When the pH of the water to be treated is adjusted to a range of 8 to 9 in the pH adjustment step, the water to be treated that has been adjusted to a pH of 8 to 9 through pH adjustment is supplied to the nanofiltration device 11, and In the filter device 11, a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step); , process the ammonia gas discharged in the nanofiltration step to obtain treated water (ammonia treatment step). In the ammonia treatment step, the ammonia gas is recovered from the NF permeated water, or the ammonia gas is decomposed.

It is also possible to use a semi-permeable membrane for the NF concentrated water obtained in the nanofiltration device 11 to perform semi-permeable membrane treatment. The NF concentrated water obtained in the nanofiltration device 11 is pressurized and delivered to the first space 14 from the inlet of the first space of the membrane module 10 through the piping 24 by the pump 18 when the valve 23 is opened. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. Part of the moisture contained in the pressurized NF concentrated water passes through the semipermeable membrane 12 and permeates from the first space 14 to the second space 16 . At this time, since most of the ions and the like cannot permeate the semipermeable membrane 12, the water in the first space 14 that has not permeated the semipermeable membrane 12 is concentrated. On the other hand, in the second space 16, a part of the concentrated water flowing through the pipe 34 merges with the permeated water with a lower ion concentration permeated through the semi-permeable membrane 12 to exert a dilution effect. The concentrated water obtained in the first space 14 is discharged from the outlet of the first space through the pipe 28, and at least a part of the concentrated water passes through the pipe 34 branched from the pipe 28 when the valve 32 is open, and is transferred from the thin film module 10 The second space inlet conveys and circulates to the second space 16 . The dilution water that can also be obtained in the second space 16 is discharged from the outlet of the second space through the piping 36, and at least a part of the dilution water is sent back to the front stage of the nanofiltration device 11, that is, to the pump 21 in the piping 25. Upstream side (return step). Here, in the membrane module 10, the first space 14 is pressurized, and the moisture contained in the NF concentrated water in the first space 14 permeates into the second space 16 through the semi-permeable membrane 12, and then in the first space 14 to obtain concentrated water (concentration step), and at the same time obtain dilution water (dilution step) in the second space 16 (the above is the semipermeable membrane treatment step).

Here, the pipes 24, 28, 34, pump 18, etc. play a role of "supplying NF concentrated water to the first space 14 of the membrane module 10 and supplying at least a part of the concentrated water obtained from the outlet of the first space 14 to the The function of the "supply mechanism" of the second space 16 of the film module 10. The piping 36 and the like function as "a return mechanism for returning at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second space 16 can be discharged out of the system through the pipe 36, and can also be discharged out of the system after being transported to the dilution water tank for storage as needed, and can also be reused. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

In the above-mentioned manner, the concentrated water with reduced ammonia and silica content is recovered from the treated water containing the treatment target (namely, ammonia and silica), and the volume reduction treatment of the treated water is carried out. In addition, NF permeated water, concentrated water, and diluted water can be reused.

Alternatively, in the above-mentioned manner, the volume reduction treatment of the treated water is carried out by recovering the ammonia-concentrated water in which the silica is reduced from the treated water containing the treatment object (that is, ammonia and silica).

By making the NF concentrated water flow into the first space 14 of the membrane module 10, and making at least a part of the concentrated water obtained in the first space 14 flow into the second space 16, the first space of the semipermeable membrane 12 can be reduced. The osmotic pressure difference between the side of the space 14 and the side of the second space 16 further concentrates high-concentration ions in the NF concentrated water with less energy consumption. That is, NF concentrated water containing high-concentration ions can be concentrated at low cost, and the amount of waste liquid with high ion concentration can be reduced.

Regarding the adjustment method for adjusting the supply flow rate of NF concentrated water to the membrane module 10, the flow rate of permeate water, and the flow rate of concentrated water, for example, the following method may be implemented.

An inverter 20 for controlling the driving frequency is installed on the pump 18 to adjust the supply flow rate of NF concentrated water to the membrane module 10 . It is preferable to install the frequency converter 20 on the pump 18, but it is not necessary to install it. As long as "the supply of NF concentrated water is implemented on the side of the first space 14, a valve 23 is set at the outlet of the first space 14, and a valve 32 is set before the entrance of the second space 16, and the valve 23 and the valve 32 are adjusted manually or automatically. The degree of opening is to adjust the ratio of the flow rate of water supplied to the first space 14 side to the flow rate of water supplied to the second space 16 side.

When the permeate water flow rate and concentrated water flow rate are insufficient, it is sufficient to increase the frequency of the frequency converter 20 of the pump 18 to increase the supply of NF concentrated water.

An adjustable opening and closing valve 23 is provided at the outlet of the first space 14 of the piping 28 , and the flow of concentrated water or the pressure at the entrance of the first space 14 and the outlet of the first space 14 can be adjusted by using the opening of the valve 23 .

Through these operations, the pressure and various flow rates on the side of the first space 14 can be adjusted to a predetermined value.

In addition, a concentrated water tank for storing concentrated water may be provided in the middle of the piping 34, and the NF concentrated water may be supplied to the first space 14 side and the concentrated water may be supplied to the second space 16 side by separate pumps. When supplying NF concentrated water and concentrated water with separate pumps, an inverter for controlling the driving frequency may be provided for each pump.

By passing the NF concentrated water to the side of the first space 14 and passing the concentrated water of similar concentration to the side of the second space 16, the osmotic pressure generated by the semi-permeable membrane 12 can be reduced, thereby reducing the required pressure. As a result, NF concentrated water can be concentrated to a concentration that cannot be concentrated by the conventional reverse osmosis membrane method.

The inlet pressure of the first space 14 should be set at the range below 7MPa; The inlet pressure of the second space 16 should be set at a pressure smaller than the inlet pressure of the first space 14; The inlet pressure of the second space 16 should be set at the first 50% or less of the inlet pressure of a space 14. In this way, the risk of damage to the semi-permeable membrane due to pressure can be reduced.

It is desirable to make the flow rate on the side of the first space 14 larger than the flow rate on the side of the second space 16 . If the flow rate on the first space 14 side is lower than the flow rate on the second space 16 side, the permeate flux may be too high. For example, the pump 18, the inverter 20, the valve 22, the valve 23, and the valve 32, etc., function as "a flow rate adjustment mechanism that makes the flow rate in the first space larger than the flow rate in the second space".

If the permeate flux is too high, the concentration difference will become larger, the risk of fouling will increase, and problems such as pressure becoming too high may occur. In addition, if the permeate flux is too small, the concentration efficiency may be deteriorated. From these viewpoints, the permeation flux of the membrane module 10 is preferably set in the range of 0.005 m/d to 0.05 m/d, more preferably in the range of 0.015 m/d to 0.04 m/d. In addition, the permeate flux is defined as the permeate flow per unit time and unit membrane area. For example, the pump 18, the frequency converter 20, the valve 22, the valve 23, the valve 32, etc., function as "a permeation flux adjustment mechanism that controls the permeation flux within the above-mentioned range".

In addition, the installation position and number of valves are only examples, and the valves may be more than those shown in Fig. 9 and Fig. 10, and may be installed in at least one of other piping. In addition, a flow measurement mechanism (that is, a flow meter) for measuring a flow rate or a pressure measurement mechanism (that is, a pressure gauge) for measuring a pressure may be provided in at least one of the piping.

In the water treatment method and water treatment device of this embodiment, a multi-stage semi-permeable membrane module can also be used. Examples of water treatment devices with these structures are shown in FIG. 11 , FIG. 12 , and FIG. 13 . The water treatment device shown in Figure 11, Figure 12, and Figure 13 has a structure in which three sections of semi-permeable membrane modules are combined in series.

The water treatment device 11 shown in Figure 11 is equipped with: a pH adjustment device 13, which is used as a pH adjustment mechanism to adjust the pH of the water to be treated to a range of 7 to 9; and a nanofiltration device 11, which is used as a nanofiltration mechanism. , use nanofiltration membrane for the treated water with adjusted pH to obtain NF permeate water and NF concentrated water. The water treatment device 11 can also be provided with: for example, the 1st section membrane module 10a, the 2nd section membrane module 10b, and the 3rd section membrane module 10c, which, as a semipermeable membrane treatment mechanism, are separated by a semipermeable membrane 12. The first space (concentration side) 14 and the second space (permeation side) 16 are connected into multiple sections of semi-permeable membrane modules. Using these modules, the NF concentrated water of the nanofiltration device 11 can flow to the first section The first space 14 of the semi-permeable membrane module, the first space 14 is pressurized, so that the moisture contained in the NF concentrated water permeates through the semi-permeable membrane 12 to obtain concentrated water, from which the concentrated water is used in the next semi-permeable The permeable membrane module obtains concentrated water, and at the same time, a part of the NF concentrated water or a part of the concentrated water is circulated to the second space 16 of the semipermeable membrane module of each section to obtain dilution water. Each film module has a first space 14 and a second space 16 separated by a semipermeable membrane 12 . The water treatment device 11 may also be provided with: a dilution water tank 60a storing dilution water from the first stage membrane module 10a, a dilution water tank 60b storing dilution water from the second stage membrane module 10b, and a dilution water tank 60b storing dilution water from the third stage film module 10a. The dilution water tank 60c for the dilution water of the module 10c. The membrane module 10 is "supply the NF concentrated water to the first space and the second space of the membrane module of the first stage, and supply the concentrated water to the first space and the second space of the membrane module of the next stage in sequence." Two space, to carry out concentration processing "device. The water treatment device 11 may also be equipped with a NF concentrated water tank for storing NF concentrated water between the nanofiltration device 11 and the membrane module 10 . The water treatment device 11 may also include: an ammonia treatment device 35 , which is used as an ammonia treatment mechanism for treating the ammonia gas discharged from the nanofiltration device 11 .

In the water treatment device 11 of FIG. 11 , a pipe 31 is connected to the inlet of the pH adjustment device 13 . The outlet of the pH adjusting device 13 and the inlet of the nanofiltration device 11 are connected by a pipe 25 through a pump 21 . The NF permeated water outlet of the nanofiltration device 11 and the inlet of the ammonia treatment device 35 are connected by a pipe 27 . A pipe 37 is connected to the outlet of the ammonia treatment device 35 . The NF concentrated water outlet of the nanofiltration device 11 is connected to the first space inlet of the first-stage membrane module 10 a through a pump 18 through a pipe 40 . A pipe 42 branched from the pipe 40 on the downstream side of the pump 18 is connected to the second space inlet of the membrane module 10a through the valve 22a. The outlet of the second space of the first-stage film module 10 a and the inlet of the dilution water tank 60 a are connected by a pipe 46 . The outlet of the first space of the first-stage film module 10 a and the inlet of the first space of the second-stage film module 10 b are connected by a pipe 44 . The pipe 48 branched from the pipe 44 is connected to the second space inlet of the second-stage film module 10b through the valve 22b. The outlet of the second space of the second-stage film module 10b and the inlet of the dilution tank 60b are connected by a pipe 52 . The outlet of the first space of the second-stage film module 10b and the inlet of the first space of the third-stage film module 10c are connected by a pipe 50 . The pipe 54 branched from the pipe 50 is connected to the second space inlet of the third-stage film module 10c through the valve 22c. The outlet of the second space of the third-stage film module 10c and the inlet of the dilution water tank 60c are connected by a pipe 58 . A pipe 56 is connected to the outlet of the first space of the third-stage film module 10c through the valve 23 . The outlet of the dilution water tank 60 a is connected to the upstream side of the pump 21 in the piping 25 by a piping 59 . The outlet of the dilution tank 60 b is connected to the pipe 59 by a pipe 61 . The outlet of the dilution water tank 60c is connected to the pipe 59 by the pipe 63 .

The membrane module 10 is a multi-stage membrane module having a first space 14 and a second space 16 separated by a semi-permeable membrane 12, and supplies NF concentrated water to the first space of the membrane module of the first stage And the second space, and the concentrated water is supplied to the first space and the second space of the film module of the next section in sequence, and the first space 14 of each section is pressurized, so that the moisture contained in the first space 14 A device that penetrates into the second space 16 through the semi-permeable membrane 12 to concentrate the water. That is, in the membrane module 10 , the NF concentrated water is concentrated by the semipermeable membrane 12 , and the concentrated water is further concentrated by the semipermeable membrane 12 of the next stage.

In the water treatment device 11 , the water to be treated (ammonia-containing wastewater) containing ammonia and silica is sent to the pH adjustment device 13 through the pipe 31 . In the pH adjustment device 13 , pH adjustment of the water to be treated is carried out (pH adjustment step). The water to be treated adjusted to a pH range of 7 to 9 by performing pH adjustment is supplied to the nanofiltration device 11 through a pipe 25 by a pump 21 . In the nanofiltration device 11 , a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

In the pH adjustment step, the pH of the water to be treated is adjusted to a range of pH 7-9. By adjusting the pH of the water to be treated to a pH range of 7-9, ammonia and silicon dioxide will permeate through the nanofiltration membrane, and most of the ammonia and silicon dioxide will be contained in the NF permeated water. When the pH of the water to be treated is adjusted to a range of 8 to 9 in the pH adjustment step, the water to be treated that has been adjusted to a pH of 8 to 9 through pH adjustment is supplied to the nanofiltration device 11, and In the filter device 11, a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step); , process the ammonia gas discharged in the nanofiltration step to obtain treated water (ammonia treatment step). In the ammonia treatment step, the ammonia gas is recovered from the NF permeated water, or the ammonia gas is decomposed.

It is also possible to use a semi-permeable membrane for the NF concentrated water obtained in the nanofiltration device 11 to perform semi-permeable membrane treatment. The NF concentrated water obtained in the nanofiltration device 11 is delivered to the first space 14a of the first-stage membrane module 10a by the pump 18 through the piping 40 when the valve 23 is opened, and is diverted from the piping 40 The NF concentrated water is sent to the second space 16a of the first-stage membrane module 10a through the pipe 42 with the valve 22a opened. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. In the first stage of the membrane module 10a, the first space 14a is pressurized, and the moisture contained in the first space 14a permeates through the semi-permeable membrane 12a to the second space 16a [concentration step (first stage)], and at the same time The second space 16a receives dilution water [dilution step (paragraph 1)]. The dilution water obtained in the second space 16a of the first-stage film module 10a is stored in the dilution water tank 60a through the pipe 46 as needed. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipe 59 (return step).

The concentrated water obtained in the first space 14a of the first stage membrane module 10a is delivered to the first space 14b of the second stage membrane module 10b through the pipe 44, and the concentrated water diverted from the pipe 44 is passed through the valve 22b as In the open state, it is sent to the second space 16b of the second-stage film module 10b through the pipe 48 . In the second stage of the membrane module 10b, the first space 14b is pressurized, and the moisture contained in the first space 14b permeates through the semi-permeable membrane 12b to the second space 16b [concentration step (second stage)], and at the same time The second space 16b receives dilution water [dilution step (paragraph 2)]. The dilution water obtained in the second space 16b of the second-stage film module 10b is stored in the dilution water tank 60b through the piping 52 as needed. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipes 61 and 59 (return step).

The concentrated water obtained in the first space 14b of the second stage membrane module 10b is delivered to the first space 14c of the third stage membrane module 10c through the pipe 50, and the concentrated water diverted from the pipe 50 is passed through the valve 22c as In the open state, it is sent to the second space 16c of the third-stage film module 10c through the pipe 54 . In the third section of the membrane module 10c, the first space 14c is pressurized, and the moisture contained in the first space 14c permeates through the semi-permeable membrane 12c to the second space 16c [concentration step (third section)], and at the same time The second space 16c obtains dilution water [dilution step (paragraph 3)] (the above is the semipermeable membrane treatment step). The dilution water obtained in the second space 16c of the film module 10c in the third stage is stored in the dilution water tank 60c through the piping 58 as needed. The concentrated water obtained in the first space 14c of the third-stage membrane module 10c is discharged through the pipe 56 . At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipes 63 and 59 (return step).

Here, the pump 18, the pipes 40, 42, 44, 48, 50, 54, etc., function as the first spaces 14a, 14b of the membrane modules 10a, 10b, 10c that supply NF concentrated water or concentrated water to each stage. , 14c, the supply mechanism of the second space 16a, 16b, 16c" function. The pipes 59, 61, 63, etc. function as "a return mechanism that returns at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second spaces 16a, 16b, 16c of the film modules 10a, 10b, 10c of each section can be discharged out of the system, or can be transported to the dilution water tanks 60a, 60b, 60c for storage as needed, It can also be reused after being discharged out of the system. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

In the above-mentioned manner, from the treatment object (that is, the treated water containing ammonia and silicon dioxide), the concentrated water with reduced ammonia and silicon dioxide content (the concentrated water in the final stage) is recovered, and the treatment of the treated water is carried out. Volume reduction treatment. In addition, NF permeated water, concentrated water, and diluted water can be reused.

Alternatively, in the above-mentioned manner, the concentrated ammonia water (the concentrated water in the final stage) in which the silicon dioxide has been reduced is recovered, and the volume reduction treatment of the treated water is carried out.

The water treatment device 12 shown in Figure 12 is equipped with: a pH adjustment device 13, which is used as a pH adjustment mechanism to adjust the pH of the water to be treated to a range of 7 to 9; and a nanofiltration device 11, which is used as a nanofiltration mechanism. , use nanofiltration membrane for the treated water with adjusted pH to obtain NF permeate water and NF concentrated water. The water treatment device 12 can also be equipped with: for example, the first section of membrane module 10a, the second section of membrane module 10b, and the third section of membrane module 10c. The first space (concentration side) 14 and the second space (permeation side) 16 are connected into multiple sections of semi-permeable membrane modules. Using these modules, the NF concentrated water of the nanofiltration device 11 can flow to the first section The first space 14 of the semi-permeable membrane module, the first space 14 is pressurized, so that the moisture contained in the NF concentrated water permeates through the semi-permeable membrane 12 to obtain concentrated water, from which the concentrated water is used in the next semi-permeable The permeable membrane module obtains concentrated water, and at the same time, at least a part of the concentrated water flows into the second space 16 of the semipermeable membrane module of each section to obtain dilution water. Each film module has a first space 14 and a second space 16 separated by a semipermeable membrane 12 . The water treatment device 12 may also be equipped with: a dilution water tank 62a, which stores the dilution water from the first stage of the film module 10a; a dilution water tank 62b, which stores the dilution water from the second stage of the film module 10b; and a dilution water tank 62c, It stores the dilution water from the 3rd stage membrane module 10c. The membrane module 10 is "supply NF concentrated water to the first space of the membrane module of the first stage, and supply the concentrated water to the first space of the membrane module of the next stage and its own second space in sequence , to carry out concentration processing "device. The water treatment device 12 may also be equipped with a NF concentrated water tank for storing NF concentrated water between the nanofiltration device 11 and the membrane module 10 . The water treatment device 12 may also include: an ammonia treatment device 35 , which is used as an ammonia treatment mechanism for treating the ammonia gas discharged from the nanofiltration device 11 .

In the water treatment device 12 of FIG. 12 , a pipe 31 is connected to the inlet of the pH adjustment device 13 . The outlet of the pH adjusting device 13 and the inlet of the nanofiltration device 11 are connected by a pipe 25 through a pump 21 . The NF permeated water outlet of the nanofiltration device 11 and the inlet of the ammonia treatment device 35 are connected by a pipe 27 . A pipe 37 is connected to the outlet of the ammonia treatment device 35 . The NF concentrated water outlet of the nanofiltration device 11 is connected to the first space inlet of the first-stage membrane module 10 a through a pump 18 through a pipe 40 . The outlet of the first space of the first-stage film module 10 a and the inlet of the first space of the second-stage film module 10 b are connected by a pipe 44 . The pipe 64 branched from the pipe 44 is connected to the second space inlet of the film module 10a through the valve 32a. The outlet of the second space of the first-stage film module 10 a and the inlet of the dilution tank 62 a are connected by a pipe 66 . The outlet of the first space of the second-stage film module 10b and the inlet of the first space of the third-stage film module 10c are connected by a pipe 50 . The pipe 68 branched from the pipe 50 is connected to the second space inlet of the film module 10b through the valve 32b. The outlet of the second space of the second-stage film module 10b and the inlet of the dilution water tank 62b are connected by a pipe 70 . A pipe 56 is connected to the outlet of the first space of the third-stage film module 10c through the valve 23 . The pipe 72 branched from the pipe 56 on the upstream side of the valve 23 is connected to the second space inlet of the film module 10c through the valve 32c. The outlet of the second space of the third-stage film module 10c and the inlet of the dilution water tank 62c are connected by a pipe 74 . The outlet of the dilution water tank 62 a is connected to the upstream side of the pump 21 in the piping 25 by a piping 59 . The outlet of the dilution water tank 62 b is connected to the pipe 59 by the pipe 61 . The outlet of the dilution water tank 62c is connected to the pipe 59 by the pipe 63 .

The membrane module 10 is a multi-stage membrane module having a first space 14 and a second space 16 separated by a semi-permeable membrane 12, and supplies NF concentrated water to the first space of the membrane module of the first stage , the concentrated water is sequentially supplied to the first space of the film module of the next stage and its own second space, and the first space 14 of each stage is pressurized, thereby allowing the moisture contained in the first space 14 to permeate The semi-permeable membrane 12 penetrates into the second space 16 to concentrate the water". That is, in the membrane module 10 , the NF concentrated water is concentrated by the semipermeable membrane 12 , and the concentrated water is further concentrated by the semipermeable membrane 12 of the next stage.

In the water treatment device 12 , the water to be treated (ammonia-containing wastewater) containing ammonia and silica is sent to the pH adjustment device 13 through the pipe 31 . In the pH adjustment device 13 , pH adjustment of the water to be treated is carried out (pH adjustment step). The water to be treated adjusted to a pH range of 7 to 9 by performing pH adjustment is supplied to the nanofiltration device 11 through a pipe 25 by a pump 21 . In the nanofiltration device 11 , a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

In the pH adjustment step, the pH of the water to be treated is adjusted to a range of pH 7-9. By adjusting the pH of the water to be treated to a pH range of 7-9, ammonia and silicon dioxide will permeate through the nanofiltration membrane, and most of the ammonia and silicon dioxide will be contained in the NF permeated water. When the pH of the water to be treated is adjusted to a range of 8 to 9 in the pH adjustment step, the water to be treated that has been adjusted to a pH of 8 to 9 through pH adjustment is supplied to the nanofiltration device 11, and In the filter device 11, a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step); , process the ammonia gas discharged in the nanofiltration step to obtain treated water (ammonia treatment step). In the ammonia treatment step, the ammonia gas is recovered from the NF permeated water, or the ammonia gas is decomposed.

It is also possible to use a semi-permeable membrane for the NF concentrated water obtained in the nanofiltration device 11 to perform semi-permeable membrane treatment. The NF concentrated water obtained in the nanofiltration device 11 is delivered to the first space 14a of the first-stage membrane module 10a by the pump 18 through the piping 40 when the valve 23 is opened. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. In the first stage of the membrane module 10a, the first space 14a is pressurized, and the moisture contained in the first space 14a permeates through the semi-permeable membrane 12a to the second space 16a [concentration step (first stage)], and at the same time The second space 16a receives dilution water [dilution step (paragraph 1)]. The concentrated water obtained in the first space 14a of the first stage membrane module 10a is delivered to the first space 14b of the second stage membrane module 10b through the pipe 44, and the concentrated water diverted from the pipe 44 is passed through the valve 32a as In the open state, it is sent to the second space 16a of the first-stage film module 10a through the pipe 64 . The dilution water obtained in the second space 16a of the first-stage film module 10a is stored in the dilution water tank 62a through the piping 66 as needed. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipe 59 (return step).

In the second stage of the membrane module 10b, the first space 14b is pressurized, and the moisture contained in the first space 14b permeates through the semi-permeable membrane 12b to the second space 16b [concentration step (second stage)], and at the same time The second space 16b receives dilution water [dilution step (paragraph 2)]. The concentrated water obtained in the first space 14b of the second stage membrane module 10b is delivered to the first space 14c of the third stage membrane module 10c through the piping 50, and the concentrated water diverted from the piping 50 is passed through the valve 32b as In the open state, it is sent to the second space 16b of the second-stage film module 10b through the pipe 68 . The dilution water obtained in the second space 16b of the second-stage film module 10b is stored in the dilution water tank 62b through the piping 70 as needed. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipes 61 and 59 (return step).

In the third section of the membrane module 10c, the first space 14c is pressurized, and the moisture contained in the first space 14c permeates through the semi-permeable membrane 12c to the second space 16c [concentration step (third section)], and at the same time The second space 16c obtains dilution water [dilution step (paragraph 3)] (the above is the semipermeable membrane treatment step). The concentrated water obtained in the first space 14c of the third-stage membrane module 10c is discharged 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 72 with the valve 32c in an open state. The dilution water obtained in the second space 16c of the film module 10c in the third stage is stored in the dilution water tank 62c through the piping 74 as needed. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 , that is, the upstream side of the pump 21 in the pipe 25 through the pipes 63 and 59 (return step).

Here, the pump 18, the piping 40, 44, 64, 50, 68, 56, 72, etc. function as the first space 14a of the membrane modules 10a, 10b, 10c that supply NF concentrated water or concentrated water to each stage. , 14b, 14c, the supply mechanism of the second space 16a, 16b, 16c" function. The pipes 59, 61, 63, etc. function as "a return mechanism that returns at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second spaces 16a, 16b, 16c of the film modules 10a, 10b, 10c of each section can be discharged out of the system, or can be transported to the dilution water tanks 62a, 62b, 62c for storage as needed, It can also be reused after being discharged out of the system. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

In the above-mentioned manner, from the treatment object (that is, the treated water containing ammonia and silicon dioxide), the concentrated water with reduced ammonia and silicon dioxide content (the concentrated water in the final stage) is recovered, and the treatment of the treated water is carried out. Volume reduction treatment. In addition, NF permeated water, concentrated water, and diluted water can be reused.

Or, in the above-mentioned way, from the treatment object (that is, the treated water containing ammonia and silicon dioxide), recover the ammonia concentrated water with reduced silicon dioxide (the concentrated water in the final stage), and implement the reduction of the treated water. Compatibility.

When using multi-segment film modules, the flow on the second space side can also be carried out in series. An example of a water treatment device having such a structure is shown in FIG. 13 .

The water treatment device 13 shown in Figure 13 is equipped with: a pH adjustment device 13, which is used as a pH adjustment mechanism to adjust the pH of the treated water to a range of 7 to 9; and a nanofiltration device 11, which is used as a nanofiltration mechanism. , use nanofiltration membrane for the treated water with adjusted pH to obtain NF permeate water and NF concentrated water. The water treatment device 13 can also be equipped with: for example, the first section of membrane module 10a, the second section of membrane module 10b, and the third section of membrane module 10c. The first space (concentration side) 14 and the second space (permeation side) 16 are connected into multiple sections of semi-permeable membrane modules. Using these modules, the NF concentrated water of the nanofiltration device 11 can flow to the first section The first space 14 of the semi-permeable membrane module, the first space 14 is pressurized, so that the moisture contained in the NF concentrated water permeates through the semi-permeable membrane 12 to obtain concentrated water, from which the concentrated water is used in the next semi-permeable The permeable membrane module obtains concentrated water, and at the same time at least a part of the concentrated water or at least a part of the dilution water obtained from other semipermeable membrane modules circulates to the second space 16 of the semipermeable membrane modules of each section to obtain dilution water. Each film module has a first space 14 and a second space 16 separated by a semipermeable membrane 12 . The membrane module 10 is "supply NF concentrated water to the first space of the membrane module of the first stage, and sequentially supply the concentrated water to the first space of the membrane module of the next stage to perform concentration treatment" installation. The water treatment device 13 may also be equipped with a NF concentrated water tank for storing NF concentrated water between the nanofiltration device 11 and the membrane module 10 . The water treatment device 13 may also include: an ammonia treatment device 35 , which is used as an ammonia treatment mechanism for treating the ammonia gas discharged from the nanofiltration device 11 .

In the water treatment device 13 of FIG. 13 , a pipe 31 is connected to the inlet of the pH adjustment device 13 . The outlet of the pH adjusting device 13 and the inlet of the nanofiltration device 11 are connected by a pipe 25 through a pump 21 . The NF permeated water outlet of the nanofiltration device 11 and the inlet of the ammonia treatment device 35 are connected by a pipe 27 . A pipe 37 is connected to the outlet of the ammonia treatment device 35 . The NF concentrated water outlet of the nanofiltration device 11 is connected to the first space inlet of the first-stage membrane module 10 a through a pump 18 through a pipe 40 . The outlet of the first space of the first-stage film module 10 a and the inlet of the first space of the second-stage film module 10 b are connected by a pipe 44 . The outlet of the first space of the second-stage film module 10b and the inlet of the first space of the third-stage film module 10c are connected by a pipe 50 . A pipe 56 is connected to the outlet of the first space of the third-stage film module 10c through the valve 23 . The pipe 76 branched from the pipe 56 on the upstream side of the valve 23 is connected to the second space inlet of the film module 10c through the valve 32 . The outlet of the second space of the third-stage film module 10c and the inlet of the second space of the second-stage film module 10b are connected by a pipe 78 . The outlet of the second space of the second-stage film module 10b and the inlet of the second space of the first-stage film module 10a are connected by a pipe 80 . The outlet of the second space of the first-stage film module 10 a is connected to the upstream side of the pump 21 in the piping 25 by a piping 82 .

The membrane module 10 is a multi-stage membrane module having a first space 14 and a second space 16 separated by a semi-permeable membrane 12, and supplies NF concentrated water to the first space of the membrane module of the first stage , so that the concentrated water is serially circulated to the first space of the membrane module of the next stage, at least a part of the concentrated water of the membrane module of the final stage is supplied to the second space of itself, and the obtained dilution water is connected in series To the second space of the film module in the front section, the first space 14 of each section is pressurized, so that the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12, so that device for concentrating water. That is, in the membrane module 10 , the NF concentrated water is concentrated by the semipermeable membrane 12 , and the concentrated water is further concentrated by the semipermeable membrane 12 of the next stage.

In the water treatment device 13 , the water to be treated (ammonia-containing wastewater) containing ammonia and silica is sent to the pH adjustment device 13 through the pipe 31 . In the pH adjustment device 13 , pH adjustment of the water to be treated is carried out (pH adjustment step). The water to be treated adjusted to a pH range of 7 to 9 by performing pH adjustment is supplied to the nanofiltration device 11 through a pipe 25 by a pump 21 . In the nanofiltration device 11 , a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

In the pH adjustment step, the pH of the water to be treated is adjusted to a range of pH 7-9. By adjusting the pH of the water to be treated to a pH range of 7-9, ammonia and silicon dioxide will permeate through the nanofiltration membrane, and most of the ammonia and silicon dioxide will be contained in the NF permeated water. When the pH of the water to be treated is adjusted to a range of 8 to 9 in the pH adjustment step, the water to be treated that has been adjusted to a pH of 8 to 9 through pH adjustment is supplied to the nanofiltration device 11, and In the filter device 11, a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step); , process the ammonia gas discharged in the nanofiltration step to obtain treated water (ammonia treatment step). In the ammonia treatment step, the ammonia gas is recovered from the NF permeated water, or the ammonia gas is decomposed.

It is also possible to use a semi-permeable membrane for the NF concentrated water obtained in the nanofiltration device 11 to perform semi-permeable membrane treatment. The NF concentrated water obtained in the nanofiltration device 11 is delivered to the first space 14a of the first-stage membrane module 10a by the pump 18 through the piping 40 when the valve 23 is opened. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. On the other hand, the dilution water sent through the second space 16c of the third-stage film module 10c and the second space 16b of the second-stage film module 10b described later is sent to the first-stage film module through the pipe 80 10a of the second space 16a. In the first stage of the membrane module 10a, the first space 14a is pressurized, and the moisture contained in the first space 14a permeates through the semi-permeable membrane 12a to the second space 16a [concentration step (first stage)], and at the same time The second space 16a receives dilution water [dilution step (paragraph 1)]. 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 film module 10a is discharged through the pipe 82 . At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 through the pipe 82 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

In the second-stage film module 10b, the dilution water sent through the second space 16c of the third-stage film module 10c described later is sent to the second space 16b of the second-stage film module 10b through the pipe 78 . The first space 14b is pressurized, and the moisture contained in the first space 14b permeates through the semi-permeable membrane 12b to the second space 16b [concentration step (second paragraph)], and at the same time obtains dilution water in the second space 16b [dilution step (paragraph 2)]. 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 film module 10b is sent to the second space 16a of the first-stage film 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 as described below is sent to the second space 16c through the pipes 56 and 76 . The first space 14c is pressurized, and the moisture contained in the first space 14c permeates through the semipermeable membrane 12c to the second space 16c [concentration step (paragraph 3)], and at the same time obtains dilution water in the second space 16c [dilution step (paragraph 3) ] (The above is the semi-permeable membrane treatment step). The concentrated water obtained in the first space 14c of the third-stage membrane module 10c is discharged through the pipe 56 . The concentrated water diverted 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 film module 10c is sent to the second space 16b of the second-stage film module 10b through the pipe 78 .

Here, the pump 18, the pipes 40, 44, 50, 56, 76, 78, 80, etc., function as the first part of the membrane modules 10a, 10b, 10c that supply NF concentrated water, concentrated water, or dilution water to each stage. The function of the supply mechanism of the first space 14a, 14b, 14c, and the second space 16a, 16b, 16c". The piping 82 and the like function as "a return mechanism for returning at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second space 16a of the film module 10a can be discharged out of the system, or can be discharged out of the system after being transported to the dilution water tank for storage as needed, and can also be reused. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

In the above-mentioned manner, from the treatment object (that is, the treated water containing ammonia and silicon dioxide), the concentrated water with reduced ammonia and silicon dioxide content (the concentrated water in the final stage) is recovered, and the treatment of the treated water is carried out. Volume reduction treatment. In addition, NF permeated water, concentrated water, and diluted water can be reused.

Or, in the above-mentioned way, from the treatment object (that is, the treated water containing ammonia and silicon dioxide), recover the ammonia concentrated water with reduced silicon dioxide (the concentrated water in the final stage), and implement the reduction of the treated water. Compatibility.

In the water treatment device 11 shown in FIG. 11, the water treatment device 12 shown in FIG. 12, and the water treatment device 13 shown in FIG. The concentrated water of the module is gradually concentrated, and the concentration gradually becomes higher. Since the concentration is finally concentrated to a high concentration, by means of this method that can reduce the osmotic pressure, it can be concentrated to a concentration that is difficult to concentrate due to the influence of osmotic pressure in the conventional reverse osmosis membrane method.

When the NF concentrated water is supplied to the first-stage membrane module 10a, for example, a pressure of 7 MPa or less is applied, and the supply of concentrated water to the latter-stage membrane module can be carried out by using the pressure applied to the first-stage membrane module 10a. . The inlet pressure of the first space 14 in each film module should be set at the range below 7MPa; The inlet pressure of the second space 16 should be set at a pressure smaller than the inlet pressure of the first space 14; The inlet of the second space 16 The pressure is more preferably set at 50% or less of the inlet pressure of the first space 14 . In this way, the risk of damage to the semi-permeable membrane due to pressure can be reduced.

It is preferable to make the flow on the side of the first space 14 in each film module 10 larger than the flow on the side of the second space 16 . When the flow rate on the side of the first space 14 is lower than the flow rate on the side of the second space 16 , the flow rate on the side of the first space 14 of the subsequent film module may be insufficient. For example, the pump 18, the frequency converter 20, the valves 22a, 22b, 22c, the valve 23, the valves 32a, 32b, 32c, and the valve 32, etc., play a role of "flow regulation to make the flow rate of the first space larger than the flow rate of the second space." organization" function.

If the permeate flux is too large, the concentration polarization on the membrane surface will become larger, the risk of fouling will increase, and problems such as pressure becoming too high may occur. In addition, if the permeate flux is too small, the concentration efficiency may be deteriorated. From these viewpoints, the permeation flux of each membrane module 10 is preferably set in the range of 0.005 m/d to 0.05 m/d, more preferably in the range of 0.015 m/d to 0.04 m/d. For example, the pump 18, the inverter 20, the valves 22a, 22b, 22c, the valve 23, the valves 32a, 32b, 32c, the valve 32, etc., perform the function of "as a permeation flux adjustment mechanism that controls the permeation flux within the above range". .

In addition, the installation position and number of valves are just examples, and the valves may be more than those shown in Fig. 11, Fig. 12, and Fig. 13, and may be installed in at least one of other piping. In addition, a flow measurement mechanism (that is, a flow meter) for measuring a flow rate or a pressure measurement mechanism (that is, a pressure gauge) for measuring a pressure may be provided in at least one of the piping.

In addition, Fig. 11, Fig. 12 and Fig. 13 are only an example of the device structure, and the arrangement of the semi-permeable membrane modules and the supply method of the supply water can also be appropriately changed.

In the water treatment device of Fig. 13, since the first space and the second space of the membrane modules of each section are respectively connected in series, so compared with the water treatment device in Fig. 11 and Fig. 12, the overall water volume can be suppressed, and further can be achieved. It is better to reduce the power of the pump.

In the water treatment method and water treatment device of this embodiment, a multi-stage membrane module is used, but as the membrane module of each stage, a membrane module with a plurality of membrane modules connected in parallel can also be used. unit. Examples of water treatment devices with these structures are shown in FIGS. 14 and 15 . The water treatment device shown in Fig. 14 and Fig. 15 has "combination of 4 rows of semi-permeable membrane modules in parallel in the first section, combination of 4 rows of semi-permeable membrane modules in parallel in the 2nd section, and combination of 4 rows of semi-permeable membrane modules in parallel in the 3rd section Combine 2 rows of semi-permeable membrane modules in parallel, combine 2 rows of semi-permeable membrane modules in parallel in the fourth stage, and connect them in series to form a 4-stage structure.

The water treatment device 14 shown in Figure 14 is equipped with: a pH adjustment device 13, which is used as a pH adjustment mechanism to adjust the pH of the treated water to a range of 7 to 9; and a nanofiltration device 11, which is used as a nanofiltration mechanism. , use nanofiltration membrane for the treated water with adjusted pH to obtain NF permeate water and NF concentrated water. The water treatment device 14 can also be equipped with: for example, the first section of membrane module unit 100a, the second section of membrane module unit 100b, the third section of membrane module unit 100c, and the fourth section of membrane module unit 100d, which are used as semi-permeable The membrane treatment mechanism is a semi-permeable membrane module with a first space (concentration side) 14 and a second space (permeation side) 16 separated by a semi-permeable membrane 12 and connected into multiple sections. Using these modules, the nano The NF concentrated water from the filter device 11 flows into the first space 14 of the semi-permeable membrane module in the first stage, pressurizes the first space 14, and makes the moisture contained in the NF concentrated water permeate through the semi-permeable membrane 12 to obtain concentrated water , obtain concentrated water from the semipermeable membrane module after the next section from the concentrated water, and make a part of the NF concentrated water or a part of the concentrated water circulate to the second space 16 of the semipermeable membrane module of each section at the same time, to obtain dilute with water. The first film module unit 100a, for example, has four film modules connected in parallel; the second film module unit 100b, for example, has four film modules connected in parallel; the third film module unit 100c , for example, includes two film modules connected in parallel; the fourth-stage film module unit 100d includes, for example, two film modules connected in parallel. Each thin film module 10 has a first space 14 and a second space 16 separated by a semipermeable membrane 12 . The water treatment device 14 may also include: a NF concentrated water tank 84 for storing NF concentrated 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 "supply the NF concentrated water to the first space and the second space of each membrane module of the membrane module unit of the first stage, and supply the concentrated water to the membrane modules of the next stage sequentially." The first space and the second space of each thin film module of the group unit, so as to carry out the device of concentration treatment. The water treatment device 14 may also include: an ammonia treatment device 35 , which is used as an ammonia treatment mechanism for treating the ammonia gas discharged from the nanofiltration device 11 .

In the water treatment device 14 of FIG. 14 , a pipe 31 is connected to the inlet of the pH adjustment device 13 . The outlet of the pH adjusting device 13 and the inlet of the nanofiltration device 11 are connected by a pipe 25 through a pump 21 . The NF permeated water outlet of the nanofiltration device 11 and the inlet of the ammonia treatment device 35 are connected by a pipe 27 . A pipe 37 is connected to the outlet of the ammonia treatment device 35 . The outlet of the NF concentrated water of the nanofiltration device 11 and the inlet of the NF concentrated water tank 84 are connected by a pipe 29 . The outlet of the NF concentrated water tank 84 is connected to the inlet of the first space and the inlet of the second space of each membrane module of the first-stage membrane module unit 100 a through the pump 18 through the pipe 88 . The first space outlet of each film module of the first-stage film module unit 100a is connected to the first space inlet and the second space inlet of each film module of the second-stage film module unit 100b by a pipe 90 . The first space outlet of each film module of the second-stage film module unit 100b is connected to the first space inlet and the second space inlet of each film module of the third-stage film module unit 100c by a pipe 94 . The first space outlet of each film module of the third-stage film module unit 100c is connected to the first space inlet and the second space inlet of each film module of the fourth-stage film module unit 100d by a pipe 98 . The outlet of the first space of each membrane module of the fourth-stage membrane module unit 100d and the inlet of the concentrated water tank 86 are connected by a pipe 104 . At the second space outlet of each film module of the first section of film module unit 100a, a piping 92 is connected; at the second space outlet of each film module of the second section of film module unit 100b, a piping 96 is connected; At the second space outlet of each film module of the 3rd section film module unit 100c, the piping 102 is connected; at the second space outlet of each film module of the 4th section film module unit 100d, the piping 106 is connected; The pipes 96 , 102 , 106 may also merge with the pipe 92 . The pipe 92 is connected to the upstream side of the pump 21 in the pipe 25 .

The membrane module unit 100 is "a multistage membrane module unit having a membrane module 10 having a first space 14 and a second space 16 separated by a semipermeable membrane 12, and supplies NF concentrated water to the first stage. The first space and the second space of each film module of the film module unit of the film module unit, the concentrated water is supplied to the first space and the second space of each film module of the film module unit of the next stage in sequence, and each The first space 14 of the film module of the section is pressurized, so that the moisture contained in the first space 14 penetrates through the semi-permeable membrane 12 to the second space 16, so as to concentrate the water". That is, in the membrane module unit 100 , the NF concentrated water is concentrated by the semipermeable membrane 12 , and the concentrated water is further concentrated by the semipermeable membrane 12 of the next stage.

In the water treatment device 14 , the water to be treated (ammonia-containing wastewater) containing ammonia and silica is sent to the pH adjustment device 13 through the pipe 31 . In the pH adjustment device 13 , pH adjustment of the water to be treated is carried out (pH adjustment step). The water to be treated adjusted to a pH range of 7 to 9 by performing pH adjustment is supplied to the nanofiltration device 11 through a pipe 25 by a pump 21 . In the nanofiltration device 11 , a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

In the pH adjustment step, the pH of the water to be treated is adjusted to a range of pH 7-9. By adjusting the pH of the water to be treated to a pH range of 7-9, ammonia and silicon dioxide will permeate through the nanofiltration membrane, and most of the ammonia and silicon dioxide will be contained in the NF permeated water. When the pH of the water to be treated is adjusted to a range of 8 to 9 in the pH adjustment step, the water to be treated that has been adjusted to a pH of 8 to 9 through pH adjustment is supplied to the nanofiltration device 11, and In the filter device 11, a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step); , process the ammonia gas discharged in the nanofiltration step to obtain treated water (ammonia treatment step). In the ammonia treatment step, the ammonia gas is recovered from the NF permeated water, or the ammonia gas is decomposed.

It is also possible to use a semi-permeable membrane for the NF concentrated water obtained in the nanofiltration device 11 to perform semi-permeable membrane treatment. The NF concentrated water obtained by the nanofiltration device 11, after being stored in the NF concentrated water tank 84 as needed, is transported from the NF concentrated water tank 84 to each part of the first stage membrane module unit 100a through the piping 88 by using the pump 18. The first space 14 and the second space 16 of the film module. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. In each film module of the film module unit 100a of the first section, the first space 14 is pressurized, and the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 [concentrating step (first paragraph)], while obtaining dilution water in the second space 16 [dilution step (paragraph 1)]. The dilution water obtained in the second space 16 of the film module 10 in the first stage is stored in the dilution water tank through the pipe 92 as needed and then discharged. At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 through the pipe 92 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

The concentrated water obtained in the first space 14 of each film module of the first stage film module unit 100a is delivered to the first space 14 and Second space 16. In each membrane module of the second stage membrane module unit 100b, the first space 14 is pressurized, and the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 [concentrating step (second paragraph)], while obtaining dilution water in the second space 16 [dilution step (paragraph 2)]. The dilution water obtained in the second spaces 16 of the membrane modules of the second-stage membrane module unit 100b is stored in the dilution water tank through the piping 96 as needed and then discharged. At least a part of the dilution water may be returned to the front stage of the nanofiltration device 11 through the pipes 96 and 92 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

The concentrated water obtained in the first space 14 of each membrane module of the second stage membrane module unit 100b is delivered to the first space 14 and Second space 16. In each film module of the 3rd stage film module unit 100c, the first space 14 is pressurized, and the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 [concentrating step (3rd step paragraph)], while obtaining dilution water in the second space 16 [dilution step (paragraph 3)]. The dilution water obtained in the second spaces 16 of the membrane modules of the third-stage membrane module unit 100c is stored in the dilution water tank through the piping 102 as needed and then discharged. At least a part of the dilution water may be returned to the front stage of the nanofiltration device 11 through the pipes 102 , 96 , 92 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

The concentrated water obtained in the first space 14 of each membrane module of the 3rd stage membrane module unit 100c is delivered to the first space 14 and Second space 16. In each film module of the 4th stage film module unit 100d, the first space 14 is pressurized, and the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 [concentrating step (4th step paragraph)], and at the same time obtain dilution water in the second space 16 [dilution step (paragraph 4)] (the above is the semipermeable membrane treatment step). 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 through the pipe 104 as needed and then discharged. The dilution water obtained in the second spaces 16 of the membrane modules of the fourth membrane module unit 100d is stored in the dilution water tank through the piping 106 as needed and then discharged. At least a part of the dilution water may be returned to the front stage of the nanofiltration device 11 through the pipes 106 , 102 , 96 , 92 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

Here, the pump 18, the piping 88, 90, 94, 98, etc., function as "the first function of each membrane module unit 100a, 100b, 100c, 100d that supplies NF concentrated water or concentrated water to each stage." Space 14, the function of the supply mechanism of the second space 16". The pipes 92, 96, 102, 106, etc. function as "a return mechanism that returns at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second spaces 16 of the film modules of the film module units 100a, 100b, 100c, and 100d in each section can be discharged out of the system, or can be discharged after being transported to the dilution tank for storage as needed It can also be reused outside the system. At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

In the above-mentioned manner, from the treatment object (that is, the treated water containing ammonia and silicon dioxide), the concentrated water with reduced ammonia and silicon dioxide content (the concentrated water in the final stage) is recovered, and the treatment of the treated water is carried out. Volume reduction treatment. In addition, NF permeated water, concentrated water, and diluted water can be reused.

Or, in the above-mentioned way, from the treatment object (that is, the treated water containing ammonia and silicon dioxide), recover the ammonia concentrated water with reduced silicon dioxide (the concentrated water in the final stage), and implement the reduction of the treated water. Compatibility.

The water treatment device 15 shown in Figure 15 is equipped with: a pH adjustment device 13, which is used as a pH adjustment mechanism to adjust the pH of the water to be treated to a range of 7 to 9; and a nanofiltration device 11, which is used as a nanofiltration mechanism. , use nanofiltration membrane for the treated water with adjusted pH to obtain NF permeate water and NF concentrated water. The water treatment device 15 can also be equipped with: for example, the first section of membrane module unit 100a, the second section of membrane module unit 100b, the third section of membrane module unit 100c, and the fourth section of membrane module unit 100d, which serve as semi-permeable The membrane treatment mechanism is a semi-permeable membrane module with a first space (concentration side) 14 and a second space (permeation side) 16 separated by a semi-permeable membrane 12 and connected into multiple sections. Using these modules, the nano The NF concentrated water from the filter device 11 flows into the first space 14 of the semi-permeable membrane module of the first stage, and the first space 14 is pressurized so that the moisture contained in the NF concentrated water permeates through the semi-permeable membrane 12 to obtain concentrated water. The concentrated water is obtained from the semi-permeable membrane module of the next stage and later, and at least a part of the concentrated water or at least part of the dilution water obtained from other semi-permeable membrane modules is circulated to the semi-permeable membrane of each stage The second space 16 of the module to obtain dilution water. The first film module unit 100a, for example, has four film modules connected in parallel; the second film module unit 100b, for example, has four film modules connected in parallel; the third film module unit 100c , for example, includes two film modules connected in parallel; the fourth-stage film module unit 100d includes, for example, two film modules connected in parallel. Each thin film module 10 has a first space 14 and a second space 16 separated by a semipermeable membrane 12 . The water treatment device 15 may also include: a NF concentrated water tank 84 for storing NF concentrated 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 "supply NF concentrated water to the first space of the membrane module of the first stage, and supply the concentrated water to the first space of the membrane module of the next stage in order to carry out concentration treatment "installation. The water treatment device 15 may also include: an ammonia treatment device 35 , which is used as an ammonia treatment mechanism for treating the ammonia gas discharged from the nanofiltration device 11 .

In the water treatment device 15 of FIG. 15 , a pipe 31 is connected to the inlet of the pH adjustment device 13 . The outlet of the pH adjusting device 13 and the inlet of the nanofiltration device 11 are connected by a pipe 25 through a pump 21 . The NF permeated water outlet of the nanofiltration device 11 and the inlet of the ammonia treatment device 35 are connected by a pipe 27 . A pipe 37 is connected to the outlet of the ammonia treatment device 35 . The outlet of the NF concentrated water of the nanofiltration device 11 and the inlet of the NF concentrated water tank 84 are connected by a pipe 29 . The outlet of the NF concentrated water tank 84 is connected to the inlet of the first space of each membrane module of the first-stage membrane module unit 100 a through the pump 18 through the pipe 108 . The first space outlet of each film module of the first-stage film module unit 100 a and the first space inlet of each film module of the second-stage film module unit 100 b are connected by a pipe 110 . The first space outlet of each film module of the second-stage film module unit 100b and the first space inlet of each film module of the third-stage film module unit 100c are connected by a pipe 112 . The first space outlet of each film module of the third-stage film module unit 100c and the first space inlet of each film module of the fourth-stage film module unit 100d are connected by a pipe 114 . The outlet of the first space of each membrane module of the fourth-stage membrane module unit 100d and the inlet of the concentrated water tank 86 are connected by a pipe 116 . A pipe 118 branched from the pipe 116 is connected to the second space inlet of each film module of the fourth-stage film module unit 100d. The outlet of the second space of each film module of the fourth-stage film module unit 100d and the inlet of the second space of each film module of the third-stage film module unit 100c are connected by a pipe 120 . The outlet of the second space of each film module of the third-stage film module unit 100c and the inlet of the second space of each film module of the second-stage film module unit 100b are connected by a pipe 122 . The outlet of the second space of each film module of the second-stage film module unit 100 b and the inlet of the second space of each film module of the first-stage film module unit 100 a are connected by a pipe 124 . The outlet of the second space of each membrane module of the first-stage membrane module unit 100 a is connected to the upstream side of the pump 21 in the pipeline 25 by a pipeline 126 .

The membrane module unit 100 is "a multistage membrane module unit having a membrane module 10 having a first space 14 and a second space 16 separated by a semipermeable membrane 12, and supplies NF concentrated water to the first stage. The first space of each thin film module of the thin film module unit, make this concentrated water flow to the first space of each thin film module of the thin film module unit of the next stage sequentially in series, the thin film module unit of final stage At least a part of the concentrated water of each membrane module is supplied to the second space of itself, so that the obtained dilution water is circulated in series to the second space 16 of each membrane module of the membrane module unit of the previous section, and each section The first space 14 is pressurized, whereby the moisture contained in the first space 14 permeates through the semi-permeable membrane 12 to the second space 16, so as to concentrate the water". That is, in the membrane module unit 100 , the NF concentrated water is concentrated by the semipermeable membrane 12 , and the concentrated water is further concentrated by the semipermeable membrane 12 of the next stage.

In the water treatment device 15 , the water to be treated (ammonia-containing wastewater) containing ammonia and silica is sent to the pH adjustment device 13 through the pipe 31 . In the pH adjustment device 13 , pH adjustment of the water to be treated is carried out (pH adjustment step). The water to be treated adjusted to a pH range of 7 to 9 by performing pH adjustment is supplied to the nanofiltration device 11 through a pipe 25 by a pump 21 . In the nanofiltration device 11 , a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step). The NF permeated water is discharged through the pipe 27 .

In the pH adjustment step, the pH of the water to be treated is adjusted to a range of pH 7-9. By adjusting the pH of the water to be treated to a pH range of 7-9, ammonia and silicon dioxide will permeate through the nanofiltration membrane, and most of the ammonia and silicon dioxide will be contained in the NF permeated water. When the pH of the water to be treated is adjusted to a range of 8 to 9 in the pH adjustment step, the water to be treated that has been adjusted to a pH of 8 to 9 through pH adjustment is supplied to the nanofiltration device 11, and In the filter device 11, a nanofiltration membrane is used for the water to be treated to obtain NF permeated water and NF concentrated water (nanofiltration step); Treat the ammonia gas discharged in the nanofiltration step to obtain treated water (ammonia treatment step). In the ammonia treatment step, the ammonia gas is recovered from the NF permeated water, or the ammonia gas is decomposed.

It is also possible to use a semi-permeable membrane for the NF concentrated water obtained in the nanofiltration device 11 to perform semi-permeable membrane treatment. The NF concentrated water obtained by the nanofiltration device 11 is stored in the NF concentrated water tank 84 according to the needs, and then is transported from the NF concentrated water tank 84 to each membrane module of the first stage membrane module unit 100a through the piping 108 by using the pump 18 The first space14. For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. On the other hand, through the second space 16 of each film module of the fourth stage film module unit 100d described later, the second space 16 of each film module of the third stage film module unit 100c, the second stage film module The dilution water sent from the second space 16 of each film module of the group unit 100b is sent to the second space 16 of each film module of the first-stage film module unit 100a through the pipe 124 . In each film module of the film module unit 100a of the first section, the first space 14 is pressurized, and the moisture contained in the first space 14 penetrates into the second space 16 through the semi-permeable membrane 12 [concentrating step (first paragraph)], while obtaining dilution water in the second space 16 [dilution step (paragraph 1)]. 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 the pipe 110 . The dilution water obtained in the second space 16 of each membrane module of the first-stage membrane module unit 100 a is discharged through the pipe 126 . At least a part of the dilution water may be sent back to the front stage of the nanofiltration device 11 through the pipe 126 , that is, to the upstream side of the pump 21 in the pipe 25 (return step).

In each film module of the 2nd stage film module unit 100b, through the second space 16 of each film module of the 4th stage film module unit 100d described later, each film module of the 3rd stage film module unit 100c The dilution water sent from the second space 16 of the group is sent to the second space 16 of each film module of the second-stage film module unit 100b through the pipe 122 . The first space 14 is pressurized, and the water contained in the first space 14 permeates through the semi-permeable membrane 12 to the second space 16 [concentration step (second paragraph)], and at the same time obtains dilution water in the second space 16 [dilution step (paragraph 2)]. 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 film module of the second-stage film module unit 100b is sent to the second space 16 of each film module of the first-stage film module unit 100a through the pipe 124 .

In each of the film modules of the third stage of the film module unit 100c, the dilution water delivered through the second space 16 of each of the film modules of the fourth stage of the film module unit 100d described later passes through the piping 120 and is sent to the first stage. The second space 16 of each film module of the three-stage film module unit 100c. The first space 14 is pressurized, and the moisture contained in the first space 14 permeates through the semipermeable membrane 12 to the second space 16 [concentration step (3rd paragraph)], and at the same time obtains dilution water in the second space 16 [dilution step (paragraph 3)]. The concentrated water obtained in the first space 14 of each membrane module of the third-stage membrane module unit 100c is sent to the first space 14 of each membrane module of the fourth-stage membrane module unit 100d through the piping 114 . The dilution water obtained in the second space 16 of each film module of the third-stage film module unit 100c is sent to the second space 16 of each film module of the second-stage film module unit 100b through the pipe 122 .

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 as described below passes through pipes 116, 118 Transported to the second space 16. The first space 14 is pressurized, and the moisture contained in the first space 14 permeates through the semi-permeable membrane 12 to the second space 16 [concentration step (paragraph 4)], and at the same time obtains dilution water in the second space 16 [dilution step (paragraph 4)] (the above is the semi-permeable membrane treatment step). 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 through the pipe 116 as needed and then discharged. The concentrated water branched from the pipe 116 is sent through the pipe 118 to the second space 16 of each membrane module of the fourth-stage membrane module unit 100d. The dilution water obtained in the second space 16 of each film module of the fourth-stage film module unit 100d is sent to the second space 16 of each film module of the third-stage film module unit 100c through the pipe 120 .

Here, the pump 18, piping 108, 110, 112, 114, 116, 118, 120, 122, 124, etc., function as "the membrane module unit 100a, which supplies NF concentrated water, concentrated water, or dilution water to each stage. 100b, 100c, 100d the function of the "supply mechanism" of the first space 14 and the second space 16 of each film module. The piping 126 and the like function as "a return mechanism for returning at least a part of the dilution water obtained in the membrane module 10 to the front stage of the nanofiltration device 11".

The dilution water obtained in the second space 16 of each film module of the film module unit 100a can be discharged out of the system, and can also be discharged out of the system after being transported to the dilution tank for storage according to needs, and can also be reused. . At least a part of the dilution water may be sent back to the upstream side of the pump 21 in the piping 25 to be mixed with the NF concentrated water, for example. Other treatments, such as reverse osmosis membrane treatment, can also be further performed on at least a portion of the dilution water.

In the above-mentioned manner, from the treatment object (that is, the treated water containing ammonia and silicon dioxide), the concentrated water with reduced ammonia and silicon dioxide content (the concentrated water in the final stage) is recovered, and the treatment of the treated water is carried out. Volume reduction treatment. In addition, NF permeated water, concentrated water, and diluted water can be reused.

Or, in the above-mentioned way, from the treatment object (that is, the treated water containing ammonia and silicon dioxide), recover the ammonia concentrated water with reduced silicon dioxide (the concentrated water in the final stage), and implement the reduction of the treated water. Compatibility.

When the NF concentrated water is supplied to each membrane module of the first-stage membrane module unit 100a, for example, a pressure of 7 MPa or less is applied, and the supply of concentrated water to the membrane module unit of the rear stage only needs to be performed by using the first-stage membrane module unit The pressure applied by each film module of 100a can be implemented. The inlet pressure of the first space 14 in each film module should be set at the range below 7MPa; The inlet pressure of the second space 16 should be set at a pressure smaller than the inlet pressure of the first space 14; The inlet of the second space 16 The pressure is more preferably set at 50% or less of the inlet pressure of the first space 14 . In this way, the risk of damage to the semi-permeable membrane due to pressure can be reduced.

It is preferable to make the flow on the side of the first space 14 in each film module 10 larger than the flow on the side of the second space 16 . When the flow rate on the side of the first space 14 is lower than the flow rate on the side of the second space 16 , the flow rate on the side of the first space 14 of the subsequent film module may be insufficient. For example, the pump 18 and the like function as "a flow rate adjustment mechanism that makes the flow rate in the first space larger than the flow rate in the second space".

If the permeate flux is too high, the concentration difference will become larger, the risk of fouling will increase, and problems such as pressure becoming too high may occur. In addition, if the permeate flux is too small, the concentration efficiency may be deteriorated. From these viewpoints, the permeation flux of each membrane module 10 is preferably set in the range of 0.005 m/d to 0.05 m/d, more preferably in the range of 0.015 m/d to 0.04 m/d. For example, the pump 18 and the like function as "a permeate flux adjustment mechanism that controls the permeate flux within the above-mentioned range".

In addition, a valve may be provided in at least one of each piping, and the installation position and number of valves are not particularly limited. In addition, a flow measurement mechanism (that is, a flow meter) for measuring a flow rate or a pressure measurement mechanism (that is, a pressure gauge) for measuring a pressure may be provided in at least one of the piping.

In addition, Fig. 14 and Fig. 15 are only an example of the device structure, and the number of stages, the number of parallel connections, the arrangement of the semi-permeable membrane modules, and the method of supplying water can also be changed appropriately.

In order to concentrate the substances to be recovered in the NF concentrated water to a better concentration in the membrane module, the membrane module should be connected in series to form a plurality of sections. When a multi-stage membrane module is used as in the water treatment apparatuses 11, 12, 13, 14, 15, the number of stages of the membrane module may be determined according to the target treatment water concentration or the like. For example, when it is desired to obtain high-concentration treated water from low-concentration NF concentrated water, it is only necessary to increase the number of stages of the membrane module unit.

When like water treatment apparatus 14,15, when using the film module unit that possesses the plurality of film modules connected in parallel as the film module of each stage, the number of the film modules in each film module unit, as long as according to The flow rate of NF concentrated water and the like may be determined.

Concentration water tanks or dilution water tanks can also be installed in more than one stage of the membrane module, and concentration water tanks or dilution water tanks can also be installed in the membrane modules of each stage.

The water to be treated in the water treatment devices and water treatment methods shown in FIGS. 9 to 16 , that is, wastewater, is, for example, water containing ammonia and silicon dioxide, but is not particularly limited. The water to be treated is, for example, water containing divalent anions such as sulfate ions, ammonium ions, and silica, and examples thereof include wastewater discharged from semiconductor factories, wastewater discharged from chemical factories, and the like. In particular, in semiconductor factories, ammonia is used for cleaning of wafers, etc., and sulfuric acid is used for cleaning treatment of ammonia. Therefore, divalent anions such as ammonium ions and sulfate ions are contained in the wastewater. Regarding the effective utilization of wastewater, ammonia and sulfuric acid in the wastewater are recovered and reused.

The water to be treated before being sent to the nanofiltration device 11 (when equipped with a pretreatment mechanism, after the pretreatment and before being sent to the nanofiltration device 11), for example, contains more than 1000 mg/L of ammonium ions, and contains 2000 ~100000mg/L is a better aspect. The water to be treated further, for example, contains more than 1000 mg/L of divalent anions such as sulfate ions, contains more than 5 mg/L of silicon dioxide, contains 6000-250000 mg/L of divalent anions such as sulfate ions, contains 5 ~50mg/L silicon dioxide is a better form.

As for the nanofiltration device 11 , the nanofiltration membrane (NF membrane), and the semipermeable membrane 12 , the same ones as above can be used.

The recovered material recovered from the concentrated water is the dissolved solid content (TDS) contained in the NF concentrated water, and the dissolved solid content includes, for example, inorganic salts such as sodium sulfate, calcium sulfate, sodium chloride, and calcium chloride. wait.

The water treatment method and water treatment device of this embodiment may also include, for example, the use of precision filtration membranes (MF membranes), ultrafiltration membranes (UF membranes), etc. Membrane treatment step (membrane treatment mechanism), reverse osmosis membrane treatment step (reverse osmosis membrane treatment mechanism), coagulation precipitation treatment step (coagulation precipitation treatment mechanism), organic matter removal treatment step (organic matter removal treatment mechanism), pH adjustment step (pH adjustment Mechanism), temperature adjustment step (temperature adjustment mechanism), at least one pretreatment step (pretreatment mechanism).

When suspended matter is contained, pretreatments such as coagulation sedimentation, membrane separation, pressurized flotation, etc. may be performed in the preceding stage of the nanofiltration step (nanofiltration device 11 ).

It is also possible to adjust the temperature of the water to be treated in the preceding stage of the nanofiltration step (nanofiltration device 11 ). An example of a water treatment device having such a structure is shown in FIG. 16 .

The water treatment device 16 of Fig. 16, for example, in addition to the structure of the water treatment device 10 of Fig. 10, may also be equipped with a temperature adjustment device 15 at the front stage of the nanofiltration step (nanofiltration device 11), as an implementation The temperature adjustment mechanism of the temperature adjustment of the treatment water.

In the water treatment device 16 of FIG. 16 , a pipe 31 is connected to the inlet of the pH adjustment device 13 . The outlet of the pH adjustment device 13 and the inlet of the temperature adjustment device 15 are connected by a pipe 33 . The outlet of the temperature adjustment device 15 and the inlet of the nanofiltration device 11 are connected by a pipe 25 through a pump 21 . The connection order of the pH adjustment device 13 and the temperature adjustment device 15 may also be reversed. The other structures are the same as those of the water treatment device 10 in FIG. 10 . In the water treatment apparatus 9, 11-15 of FIG. 9, FIG. 11-FIG. 15, the temperature adjustment apparatus 15 can also be provided.

In the water treatment device 16 , the water to be treated, that is, the water to be treated containing ammonia (ammonia-containing wastewater) is sent to the pH adjustment device 13 through the pipe 31 . In the pH adjustment device 13 , pH adjustment of the water to be treated is carried out (pH adjustment step). The to-be-processed water adjusted to a pH range of 7 to 9 by performing pH adjustment is sent to the temperature adjustment device 15 through the pipe 33 . In the temperature adjustment device 15 , temperature adjustment of the water to be treated is carried out (temperature adjustment step). The connection sequence of the pH adjustment device 13 and the temperature adjustment device 15 can also be reversed, and after the temperature adjustment of the treated water (temperature adjustment step), the pH adjustment of the treated water whose temperature has been adjusted (pH adjustment step) can be implemented. ).

The treated water subjected to pH adjustment and temperature adjustment is supplied to the nanofiltration device 11 through the pipe 25 by the pump 21 . Thereafter, a nanofiltration step is carried out similarly to the water treatment device 10 of FIG. 10 . For the communication between the nanofiltration device 11 and the membrane module 10, only the pump 21 can be used. The ammonia gas discharged from the nanofiltration step can also be treated in the ammonia treatment device 35 . It is also possible to use a semipermeable membrane for the NF concentrated water obtained in the nanofiltration device 11 to perform semipermeable membrane treatment.

In the above-mentioned manner, the concentrated water with reduced ammonia and silica content is recovered from the treated water containing the treatment target (namely, ammonia and silica), and the volume reduction treatment of the treated water is carried out. In addition, NF permeated water, concentrated water, and diluted water can be reused.

Alternatively, in the above-mentioned manner, the volume reduction treatment of the treated water is carried out by recovering the ammonia-concentrated water in which the silica is reduced from the treated water containing the treatment object (that is, ammonia and silica).

The pH adjusting device 13 in the water treatment apparatus and water treatment method of FIGS. 9 to 16 includes, for example, a pH adjusting agent adding mechanism such as a pH adjusting agent adding pipe, a pH measuring device, a pH adjusting tank, and the like. Adding a pH adjuster to the pH adjustment tank adjusts the pH of the water to be treated to a range of pH 7-9, more preferably to a range of pH 8-9, which is a better aspect. pH adjustment may be performed in piping or the like without installing a pH adjustment tank.

Examples of the pH adjuster include acids such as hydrochloric acid and sulfuric acid, alkalis such as sodium hydroxide, and the like.

As the temperature adjustment device 15, the same one as above can be used.

It is also possible to perform pH adjustment and temperature adjustment again at the rear stage of the nanofiltration device 11 and before passing through the semi-permeable membrane module. The pH and water temperature when passing through the semi-permeable membrane module can be determined according to the water quality of the treated water and the material of the semi-permeable membrane module. For example, the pH of the water to be treated is in the range of 7 to 9, and the water temperature is in the range of 20°C to 35°C, which is a preferable aspect.

pH adjustment or water temperature adjustment may be performed in the same manner as above.

The ammonia treatment device 35 is not particularly limited as long as it recovers and treats ammonia gas from NF permeated water, or decomposes and treats ammonia gas. As the ammonia treatment device 35 , for example, an ammonia stripping treatment device and the like are mentioned.

Ammonia stripping treatment device, for example, is a device with perforated plates or fillers installed inside the distillation tower. The treated water (that is, ammonia-containing water) flows in from the upper part of the distillation tower, and the steam is blown from the lower part. The treated water and Vapor contact whereby free ammonia in the ammoniacal water is swept out to the vapor side. The ammonia gas that is swept out is sent to the ammonia gas decomposition treatment device through the ammonia gas pipeline for decomposition treatment. Regarding this ammonia gas decomposition treatment, for example, there are: a method of passing through a catalyst reaction tower filled with a catalyst and decomposing it into harmless nitrogen, a method of reacting with sulfuric acid to become ammonium sulfate, etc., and it is also possible to form ammonia water and recover it for recycling. use.

This specification includes the embodiments shown below. (1) A water treatment device that recovers valuable substances from drainage, characterized by comprising: a nanofiltration mechanism that uses a nanofiltration membrane for the drainage to obtain NF permeated water and NF concentrated water; and semipermeable membrane treatment A mechanism that uses a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, allows the NF concentrated water to flow into the first space, pressurizes the first space, and makes the NF concentrated water The contained water permeates through the semi-permeable membrane to obtain concentrated water, and at the same time, a part of the NF concentrated water or at least a part of the concentrated water is circulated into the second space to obtain dilution water.

(2) A water treatment device that recovers valuable substances from drainage, characterized by comprising: a nanofiltration mechanism that uses a nanofiltration membrane for the drainage to obtain NF permeated water and NF concentrated water; and semipermeable membrane treatment A mechanism that uses a semi-permeable membrane module that has a first space and a second space separated by a semi-permeable membrane and is connected into a plurality of stages, so that the NF concentrated water flows into the first space of the semi-permeable membrane module of the first stage , the first space is pressurized, so that the moisture contained in the NF concentrated water permeates through the semipermeable membrane to obtain concentrated water, and the concentrated water is obtained from the concentrated water by using the semipermeable membrane module after the next stage, and at the same time Let the NF concentrated water or at least a part of the concentrated water or at least a part of the dilution water obtained from other semi-permeable membrane modules circulate to the second space of the semi-permeable membrane modules of each section to obtain dilution water.

(3) The water treatment device as described in (1) or (2), which further includes: a return mechanism that returns at least a part of the dilution water obtained in the semi-permeable membrane treatment mechanism to the nanometer The front section of the filter mechanism.

(4) The water treatment device described in any one of (1) to (3), wherein the nanofiltration membrane has a silica barrier rate of In the range of 0-20%, the ammonium ion blocking rate and the sulfuric acid ion blocking rate are in the range of 90%-100%.

(5) The water treatment device described in any one of (1) to (4), further comprising: a pH adjustment mechanism that adjusts the pH of the wastewater to 4 to 4 before the nanofiltration mechanism. 8 range.

(6) The water treatment device described in any one of (1) to (5), further comprising: a temperature adjustment mechanism, which adjusts the temperature of the discharged water to 20°C at the front stage of the nanofiltration mechanism ~35°C range.

(7) A water treatment method for recovering valuable substances from drainage, characterized by comprising: a nanofiltration step of using a nanofiltration membrane for the drainage to obtain NF permeated water and NF concentrated water; and semipermeable membrane treatment A step of using a semipermeable membrane module having a first space and a second space separated by a semipermeable membrane, allowing the NF concentrated water to flow into the first space, pressurizing the first space, and making the NF concentrated water The contained water permeates through the semi-permeable membrane to obtain concentrated water, and at the same time, a part of the NF concentrated water or at least a part of the concentrated water is circulated into the second space to obtain dilution water.

(8) A water treatment method for recovering valuable substances from drainage, characterized by comprising: a nanofiltration step of using a nanofiltration membrane for the drainage to obtain NF permeated water and NF concentrated water; and semipermeable membrane treatment The step of using a semi-permeable membrane module having a first space and a second space separated by a semi-permeable membrane and connecting multiple sections, so that the NF concentrated water flows into the first space of the semi-permeable membrane module of the first section , the first space is pressurized, so that the moisture contained in the NF concentrated water permeates through the semipermeable membrane to obtain concentrated water, and the concentrated water is obtained from the concentrated water by using the semipermeable membrane module after the next stage, and at the same time Let the NF concentrated water or at least a part of the concentrated water or at least a part of the dilution water obtained from other semi-permeable membrane modules circulate to the second space of the semi-permeable membrane modules of each section to obtain dilution water.

(9) The water treatment method described in (7) or (8), wherein at least a part of the dilution water obtained in the semipermeable membrane treatment step is returned to the previous stage of the nanofiltration step.

(10) The water treatment method described in any one of (7) to (9), wherein the wastewater contains 2000 mg/L or more of ammonium ions, contains 6000 mg/L or more of sulfate ions, and contains 5 mg/L or more of of silica.

(11) The water treatment method as described in (7) or (8), which further includes: a pH adjustment step, which adjusts the pH of the wastewater to a range of 7 to 9; in the nanofiltration step, for The pH-adjusted drainage uses the nanofiltration membrane to obtain the NF permeated water and the NF concentrated water; the drainage contains more than 1000 mg/L of ammonium ions, contains more than 1000 mg/L of divalent anions, and contains 5 mg/L above silicon dioxide.

(12) The water treatment method as described in (11), wherein in the pH adjustment step, the pH of the wastewater is adjusted to a range of 8-9; further comprising: an ammonia treatment step for treating the nano Ammonia gas discharged from the filtration step.

(13) The water treatment method as described in (11) or (12), which further includes: a semipermeable membrane treatment step, which uses a semipermeable membrane for the NF concentrated water in the latter stage of the nanofiltration step to obtain Concentrated water and diluted water.

(14) The water treatment method described in any one of (11) to (13), wherein the nanofiltration membrane has a silica rejection rate of In the range of 0-20%, the ammonium ion blocking rate and the sulfuric acid ion blocking rate are in the range of 90%-100%.

(15) The water treatment device as described in (1) or (2), further comprising: a pH adjustment mechanism, which adjusts the pH of the wastewater to a range of 7 to 9; The drainage through the pH uses the nanofiltration membrane to obtain the mechanism of the NF permeated water and the NF concentrated water; the drainage contains more than 1000 mg/L of ammonium ions, contains more than 1000 mg/L of divalent anions, and contains 5 mg/L Silicon dioxide above L.

(16) The water treatment device as described in (15), wherein the pH adjustment mechanism adjusts the pH of the wastewater to a range of 8 to 9; it further includes: an ammonia treatment mechanism for treating the nanofiltration Ammonia gas emitted by the institution.

(17) The water treatment device as described in (15) or (16), wherein it further includes: a semipermeable membrane treatment mechanism, which uses a semipermeable membrane for the NF concentrated water in the rear stage of the nanofiltration mechanism to obtain Concentrated water and diluted water.

(18) The water treatment device as described in any one of (15) to (17), wherein the nanofiltration membrane has a silica rejection rate of In the range of 0-20%, the ammonium ion blocking rate and the sulfuric acid ion blocking rate are in the range of 90%-100%.

(19) A water treatment method, which concentrates treated water containing ammonia and silicon dioxide, characterized by comprising: a pH adjustment step, which adjusts the pH of the treated water to a range of 7 to 9; Filtration step, which uses a nanofiltration membrane to obtain NF permeated water and NF concentrated water for the treated water whose pH has been adjusted; the treated water contains more than 1000 mg/L of ammonium ions, and contains more than 1000 mg/L of divalent Anion, containing more than 5mg/L of silicon dioxide.

(20) The water treatment method as described in (19), wherein, in the pH adjustment step, the pH of the water to be treated is adjusted to a range of 8 to 9; further comprising: an ammonia treatment step for treating the pH of the treated water Ammonia gas from the nanofiltration step.

(21) The water treatment method as described in (19) or (20), which further includes: a semipermeable membrane treatment step, which uses a semipermeable membrane for the NF concentrated water in the latter stage of the nanofiltration step to obtain Concentrated water and diluted water.

(22) The water treatment method described in any one of (19) to (21), wherein the nanofiltration membrane has a silica barrier rate of In the range of 0-20%, the ammonium ion blocking rate and the sulfuric acid ion blocking rate are in the range of 90%-100%.

(23) A water treatment device that concentrates treated water containing ammonia and silicon dioxide, characterized by comprising: a pH adjustment mechanism that adjusts the pH of the treated water to a range of 7 to 9; Filtration mechanism, which uses a nanofiltration membrane for the treated water with adjusted pH to obtain NF permeated water and NF concentrated water; the treated water contains more than 1000 mg/L of ammonium ions, and contains more than 1000 mg/L of divalent Anion, containing more than 5mg/L of silicon dioxide.

(24) The water treatment device as described in (23), wherein the pH adjustment mechanism adjusts the pH of the water to be treated to a range of 8 to 9; further comprising: an ammonia treatment mechanism for treating the sodium Ammonia gas discharged from the filter mechanism.

(25) The water treatment device as described in (23) or (24), wherein it further includes: a semipermeable membrane treatment mechanism, which uses a semipermeable membrane for the NF concentrated water in the rear stage of the nanofiltration mechanism to obtain Concentrated water and diluted water.

(26) The water treatment device described in any one of (23) to (25), wherein the nanofiltration membrane has a silica barrier rate of In the range of 0-20%, the ammonium ion blocking rate and the sulfuric acid ion blocking rate are in the range of 90%-100%. [Example]

Hereinafter, examples and comparative examples are given to illustrate the present invention in more detail, but the present invention is not limited to the following examples.

+-<Example 1> The treated water (drainage containing ammonia) with an ammonium ion concentration of 4500mg/L, a sulfate ion concentration of 12000mg/L, and a silicon dioxide concentration of 30mg/L is treated with a spiral NF membrane (effective pressure on the membrane surface 1MPa, 25°C , pH7 conditions, silicon dioxide barrier rate of 15%, ammonium ion barrier rate and sulfuric acid ion barrier rate of 99% film) concentrated. At this time, the pH of the water to be treated was varied in the range of 4-9. Use the molybdenum yellow light absorption method to measure the concentration of silicon dioxide in the treated water, concentrated water, and permeated water after passing through the NF membrane. The silica blocking rate was calculated from each silica concentration. The blocking rate is calculated by blocking rate% = [1-(NF permeated water silica concentration/NF supply water silica concentration)]×100. The operating conditions of the NF membrane are 840L/h of supplied water, 720L/h of NF concentrated water, and 120L/h of NF permeated water. The results of the blocking ratio of silicon dioxide are shown in FIG. 17 .

In addition, when the water treatment device 2 of Fig. 2 is used, the recovery rate of the NF membrane is concentrated at 60%, and the precipitation concentration of the semi-permeable membrane module silicon dioxide in the latter stage is concentrated to 120mg/L, each pH condition (water The ratio of the ammonium ion concentration of the concentrated water of the semipermeable membrane module to the ammonium ion concentration of the treated water is disclosed in Table 1. The return rate of the dilution water of the semi-permeable membrane module to the front section of the NF membrane module is 100%.

[Table 1] Treated water pH[-] 4 5 6 7 8 9 Concentration ratio of final concentrated water [times] 11.9 13 13.9 14.9 22.8 >25

As shown in Figure 17, the higher the pH of the treated water is, the lower the barrier rate of SiO2 in the NF membrane is, and SiO2 will penetrate to the permeate side of the NF membrane. That is, the silica concentration on the NF concentrated water side is not concentrated, but other coexisting concentration target substances can be concentrated. As shown in Table 1, as the pH of the water to be treated increases, the rejection rate of silicon dioxide decreases, thereby gradually increasing the concentration of the final concentrated water. When the pH is 9, it can be concentrated to a concentration exceeding the solubility of ammonium sulfate under the present concentration conditions.

<Example 2> Use NF membrane to treat water with ammonium ion concentration of 4500mg/L, sulfate ion concentration of 12000mg/L, and silicon dioxide concentration of 30mg/L. Concentrated by 60%, the precipitation concentration of silicon dioxide in the semi-permeable membrane module in the latter stage is concentrated to 120mg/L. The ammonium ion concentration of the concentrated water of the semi-permeable membrane module is changed when the return rate of the dilution water sent back to the semi-permeable membrane module at the front stage of the NF membrane is changed to 0%, 50%, and 100%. Table 2 reveals the multiplier with respect to the concentration of ammonium ions in the water to be treated.

[Table 2] Dilution water return rate[%] 0 50 100 Concentration ratio of final concentrated water [times] 9.5 12.2 14.9

As shown in Table 2, when the dilution water return rate of the semi-permeable membrane module is 0%, the concentration ratio of the final concentrated water of the semi-permeable membrane module is 9.5 times, but if the return rate is set to 50% , 100%, respectively 12.2 times, 14.9 times, the ammonium ion concentration in the final concentrated water increases.

Like this, with the device and method of the embodiment, it is possible to recover valuable substances from ammonia-containing wastewater at a high concentration.

<Example 3> The treated water (water containing ammonia) with an ammonium ion concentration of 16500mg/L and a silicon dioxide concentration of 30mg/L is treated with a spiral NF membrane (under the conditions of an effective pressure of 1MPa on the membrane surface, 25°C, and pH7, the carbon dioxide Thin film with 15% rejection of silicon, 99% rejection of ammonium ion and 99% rejection of sulfate ion) concentration. At this time, the pH of the water to be treated was varied in the range of 4-9. Use the molybdenum yellow light absorption method to measure the concentration of silicon dioxide in the treated water, concentrated water, and permeated water after passing through the NF membrane. The silica blocking rate was calculated from each silica concentration. The blocking rate is calculated by blocking rate% = [1-(NF permeated water silica concentration/NF supply water silica concentration)]×100. The operating conditions of the NF membrane are 840L/h of supplied water, 720L/h of NF concentrated water, and 120L/h of NF permeated water. The results of the blocking ratio of silicon dioxide are shown in FIG. 18 .

In addition, when using the water treatment device 10 of Fig. 10, the recovery rate of the NF membrane is concentrated at 60%, and the precipitation concentration of the semi-permeable membrane module silicon dioxide in the rear stage is concentrated to 120mg/L, each pH condition (water The ratio of the ammonium ion concentration of the concentrated water of the semipermeable membrane module to the ammonium ion concentration of the treated water is disclosed in Table 3. The return rate of the dilution water of the semi-permeable membrane module to the front section of the NF membrane module is 100%.

[table 3] Treated water pH[-] 4 5 6 7 8 9 Concentration ratio of final concentrated water [times] 11.9 13 13.9 14.9 22.8 >25

As shown in Figure 18, the higher the pH of the treated water is, the lower the barrier rate of SiO2 in the NF membrane is, and the SiO2 will penetrate to the permeate side of the NF membrane. That is, the silica concentration on the NF concentrated water side is not concentrated, but other coexisting concentration target substances can be concentrated. As shown in Table 3, as the pH of the water to be treated increases, the rejection rate of silicon dioxide decreases, thereby gradually increasing the concentration of the final concentrated water. When the pH is 9, it can be concentrated to a concentration exceeding the solubility of ammonium sulfate under the present concentration conditions.

Like this, with the device and method of the embodiment, the treated water containing ammonia and silicon dioxide (ammonia-containing wastewater) can reduce the concentration of silicon dioxide and gradually concentrate it.

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16: water treatment device 10,10a,10b,10c: film module 11: Nanofiltration device 12, 12a, 12b, 12c: semi-permeable membrane 13: pH adjustment device 14,14a,14b,14c: the first space 15: Temperature adjustment device 16, 16a, 16b, 16c: the second space P,18,21: pump INV,20: Inverter 22,22a,22b,22c,23,32,32a,32b,32c: valve 24,25,26,27,28,29,30,31,33,34,36,37,40,42,44,46,48,50,52,54,56,58,59,61,63, 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: Piping 35: Ammonia treatment device 60a, 60b, 60c, 62a, 62b, 62c: dilution tank 84: NF concentration tank 86: concentrated sink 100, 100a, 100b, 100c, 100d: film module unit

[FIG. 1] It is a schematic structural diagram which shows an example of the water treatment apparatus which concerns on embodiment of this invention. [FIG. 2] It is a schematic structural diagram which shows another example of the water treatment apparatus which concerns on embodiment of this invention. [FIG. 3] It is a schematic structural diagram which shows another example of the water treatment apparatus which concerns on embodiment of this invention. [FIG. 4] It is a schematic structural diagram which shows another example of the water treatment apparatus which concerns on embodiment of this invention. [FIG. 5] It is a schematic structural diagram which shows another example of the water treatment apparatus which concerns on embodiment of this invention. [FIG. 6] It is a schematic structural diagram which shows another example of the water treatment apparatus which concerns on embodiment of this invention. [FIG. 7] It is a schematic structural diagram which shows another example of the water treatment apparatus which concerns on embodiment of this invention. [FIG. 8] It is a schematic structural diagram which shows another example of the water treatment apparatus which concerns on embodiment of this invention. [ Fig. 9 ] is a schematic structural diagram showing an example of a water treatment device according to an embodiment of the present invention. [ Fig. 10 ] is a schematic structural diagram showing another example of the water treatment device according to the embodiment of the present invention. [ Fig. 11 ] is a schematic structural diagram showing another example of the water treatment device according to the embodiment of the present invention. [ Fig. 12 ] is a schematic structural diagram showing another example of the water treatment device according to the embodiment of the present invention. [ Fig. 13 ] is a schematic structural diagram showing another example of the water treatment device according to the embodiment of the present invention. [FIG. 14] It is a schematic structural diagram which shows another example of the water treatment apparatus which concerns on embodiment of this invention. [FIG. 15] It is a schematic structural diagram which shows another example of the water treatment apparatus which concerns on embodiment of this invention. [ Fig. 16 ] is a schematic structural view showing another example of the water treatment device according to the embodiment of the present invention. [ Fig. 17 ] is a graph showing the result of the blocking ratio of silicon dioxide in Example 1. [ Fig. 18 ] is a graph showing the result of blocking ratio of silicon dioxide in Example 3.

1,10,11,12,14,16: water treatment device

P,18,21: pump

INV,20: Inverter

22,23: valve

24,25,26,27,28,30: Piping

Claims (18)

A water treatment device that recovers valuable substances from wastewater, characterized by comprising: a nanofiltration mechanism using a nanofiltration membrane for the drainage to obtain nanofiltration permeate and nanofiltration concentrate; and A semi-permeable membrane treatment mechanism, which uses a semi-permeable membrane module having a first space and a second space separated by a semi-permeable membrane, so that the nanofiltration concentrated water flows into the first space, and pressurizes the first space , allowing the moisture contained in the nanofiltration concentrated water to permeate through the semipermeable membrane to obtain concentrated water, and at the same time allowing a part of the nanofiltration concentrated water or at least a part of the concentrated water to flow into the second space to obtain dilute with water. A water treatment device that recovers valuable substances from wastewater, characterized by comprising: a nanofiltration mechanism using a nanofiltration membrane for the drainage to obtain nanofiltration permeate and nanofiltration concentrate; and Semi-permeable membrane treatment mechanism, which uses a semi-permeable membrane module that has a first space and a second space separated by a semi-permeable membrane and is connected into multiple sections, so that the nanofiltration concentrated water flows to the semi-permeable membrane of the first section The first space of the module, the first space is pressurized, so that the water contained in the nano-filtered concentrated water permeates through the semi-permeable membrane to obtain concentrated water, from which the concentrated water is used for the next stage of semi-permeable The membrane module obtains concentrated water, and at the same time, the nano-filtered concentrated water or at least a part of the concentrated water or at least a part of the dilution water obtained from other semi-permeable membrane modules circulates to the first semi-permeable membrane module of each section Two spaces to obtain dilution water. Such as the water treatment device of claim 1 or 2, wherein, It further includes: a return mechanism, which returns at least a part of the dilution water obtained in the semi-permeable membrane treatment mechanism to the front stage of the nano-filtration mechanism. Such as the water treatment device of claim 1 or 2, wherein, The nanofiltration membrane, under the conditions of effective pressure on the membrane surface of 1 MPa, 25°C, and pH 7, the blocking rate of silicon dioxide is in the range of 0-20%, and the blocking rate of ammonium ion and sulfuric acid ion is in the range of 90%-100%. scope. Such as the water treatment device of claim 1 or 2, wherein, It further includes: a pH adjustment mechanism, which adjusts the pH of the wastewater to the range of 4-8 at the front stage of the nanofiltration mechanism. Such as the water treatment device of claim 1 or 2, wherein, It further includes: a temperature adjustment mechanism, which adjusts the temperature of the drainage to the range of 20°C to 35°C at the front stage of the nanofiltration mechanism. A water treatment method for recovering valuable substances from drainage, characterized by comprising: a nanofiltration step using a nanofiltration membrane for the drainage to obtain nanofiltration permeate and nanofiltration concentrate; and The semi-permeable membrane treatment step, which uses a semi-permeable membrane module having a first space and a second space separated by a semi-permeable membrane, makes the nanofiltration concentrated water flow into the first space, and pressurizes the first space , allowing the moisture contained in the nanofiltration concentrated water to permeate through the semipermeable membrane to obtain concentrated water, and at the same time allowing a part of the nanofiltration concentrated water or at least a part of the concentrated water to flow into the second space to obtain dilute with water. A water treatment method for recovering valuable substances from drainage, characterized by comprising: a nanofiltration step using a nanofiltration membrane for the drainage to obtain nanofiltration permeate and nanofiltration concentrate; and Semi-permeable membrane treatment step, which uses a semi-permeable membrane module that has a first space and a second space separated by a semi-permeable membrane and is connected into a plurality of sections, so that the nanofiltration concentrated water flows to the semi-permeable membrane of the first section The first space of the module, the first space is pressurized, so that the water contained in the nano-filtered concentrated water permeates through the semi-permeable membrane to obtain concentrated water, from which the concentrated water is used for the next stage of semi-permeable The membrane module obtains concentrated water, and at the same time, the nano-filtered concentrated water or at least a part of the concentrated water or at least a part of the dilution water obtained from other semi-permeable membrane modules circulates to the first semi-permeable membrane module of each section Two spaces to obtain dilution water. Such as the water treatment method of claim item 7 or 8, wherein, At least a part of the dilution water obtained in the semipermeable membrane treatment step is sent back to the previous stage of the nanofiltration step. Such as the water treatment method of claim item 7 or 8, wherein, This wastewater contains ammonium ions of 2000 mg/L or more, sulfate ions of 6000 mg/L or more, and silica of 5 mg/L or more. Such as the water treatment method of claim item 7 or 8, wherein, It further includes: a pH adjustment step, which adjusts the pH of the drainage to the range of 7-9; In the nanofiltration step, using the nanofiltration membrane for the pH-adjusted wastewater to obtain the nanofiltration permeate water and the nanofiltration concentrated water; This wastewater contains ammonium ions at 1000 mg/L or more, divalent anions at 1000 mg/L or more, and silicon dioxide at 5 mg/L or more. Such as the water treatment method of claim 11, wherein, In the pH adjustment step, the pH of the drainage is adjusted to a range of 8-9; It further includes: an ammonia treatment step, which is used to treat the ammonia gas discharged from the nanofiltration step. Such as the water treatment method of claim 11, wherein, It further includes: a semipermeable membrane treatment step, which uses a semipermeable membrane for the nanofiltration concentrated water to obtain concentrated water and dilution water in the latter stage of the nanofiltration step. Such as the water treatment method of claim 11, wherein, The nanofiltration membrane, under the conditions of effective pressure on the membrane surface of 1 MPa, 25°C, and pH 7, the blocking rate of silicon dioxide is in the range of 0-20%, and the blocking rate of ammonium ion and sulfuric acid ion is in the range of 90%-100%. scope. Such as the water treatment device of claim 1 or 2, wherein, It further includes: a pH adjustment mechanism, which adjusts the pH of the drainage to a range of 7-9; The nanofiltration mechanism is a mechanism for using the nanofiltration membrane to obtain the nanofiltration permeate water and the nanofiltration concentrated water for the pH-adjusted wastewater; This wastewater contains ammonium ions at 1000 mg/L or more, divalent anions at 1000 mg/L or more, and silicon dioxide at 5 mg/L or more. Such as the water treatment device of claim 15, wherein, adjusting the pH of the drainage to a range of 8-9 in the pH adjusting mechanism; It further includes: an ammonia treatment mechanism, which is used to process the ammonia gas discharged from the nanometer filter mechanism. Such as the water treatment device of claim 15, wherein, It further includes: a semi-permeable membrane treatment mechanism, which uses a semi-permeable membrane for the nano-filtration concentrated water to obtain concentrated water and dilution water at the rear stage of the nano-filtration mechanism. Such as the water treatment device of claim 15, wherein, The nanofiltration membrane, under the conditions of effective pressure on the membrane surface of 1 MPa, 25°C, and pH 7, the blocking rate of silicon dioxide is in the range of 0-20%, and the blocking rate of ammonium ion and sulfuric acid ion is in the range of 90%-100%. scope.