JP4941613B1 - Seawater desalination system - Google Patents

Abstract

[PROBLEMS] To produce drinking water from seawater and increase industrial water, thereby reducing water production costs.
The seawater desalination system of the present invention removes activated sludge from sewage and purifies it, and removes salt from the permeate of the purifier 1 in the first concentrated water s6 to remove industrial water s1. The first RO membrane 2 that generates water, the UF membrane 3 that removes particles in seawater, and the salt content of the treated water s5b that has permeated through the UF membrane 3 are contained in the second concentrated water s7 and removed to produce drinking water s2. The second RO membrane 4 to be stirred, the second concentrated water s7 removed by the second RO membrane 4 and the first concentrated water s6 removed by the first RO membrane 2 are stirred. Then, the salt energy of the mixed liquid stirred by the stirring device 5 is contained in the third concentrated water s9 and removed, and the pressure energy of the third RO film 6 from which the industrial water s3 is generated and the pressure energy of the second concentrated water s7 is obtained. The second motion for recovering the pressure energy of the first power recovery device 34 and the third concentrated water s9 to be recovered. Comprising the at least any of the recovery device 36.
[Selection] Figure 3

Description

  The present invention relates to a seawater desalination system for desalinating seawater and sewage.

In recent years, demand for drinking water and industrial water production in desert areas has become apparent due to global population growth and development of wide-area industries including emerging countries.
Conventionally, there exists desalination system S100 shown in FIG. 5 as a system which desalinates seawater and sewage.

Production of production water s101 (industrial water) using sewage in the desalination system S100 is performed as follows. The salinity of sewage is about 0.1%.
The sewage is sent to MBR (Membrane Bioreactor) 101 by pump p101, the activated sludge of solids in the sewage is removed by MBR101, and the MBR permeated water that has permeated MBR101 is converted to low pressure RO membrane (Reverse Osmosis Membrane by pump p102. ) 102.

Since the MBR permeated water that has passed through MBR101 has a salt concentration of about 0.1% and is low, the RO membrane is a low pressure RO membrane (reverse osmosis membrane) of about 1-2 MPa (megapascal). 102 is used.
The MBR permeated water sent by the pump p102 passes through the low-pressure RO membrane 102, so that almost half of the concentrated water s104 containing impurities such as salt is removed and desalinated, and the other half of the industrial water s101 is produced. The

On the other hand, concentrated water s104 having a volume of about ½ of sewage concentrated to a salt concentration of about 0.2% containing impurities such as salt removed by the low-pressure RO membrane 102 is sent from the low-pressure RO membrane 102 to the stirring tank 104. Is done.
Production of industrial water as production water s102 from seawater in the desalination system S100 is performed as follows. In addition, the salt concentration of seawater is about 3 to 4%.

  Seawater is fed to the UF membrane 103 by the pump p103, and the particles are removed by the UF membrane 103 and fed to the agitation tank 104. In the agitation tank 104, the UF membrane-permeated seawater that has passed through the UF membrane 103 and the concentrated water s104 having a volume of about ½ of the sewage concentrated from the sewage by the low-pressure RO membrane 102 are stirred, and then pumped. Water is sent to the medium pressure RO membrane 105 by p104.

The UF membrane-permeated seawater that has passed through the UF membrane 103 has a salt concentration of 3 to 4%, but is diluted with concentrated water s104 having a salt concentration of 0.2%, so an RO membrane with a medium pressure of about 3 to 5 MPa ( A medium pressure RO membrane 105 is used.
The mixed water s103 sent from the agitation tank 104 to the intermediate pressure RO membrane 105 by the pump p104 passes through the intermediate pressure RO membrane 105, so that about 1/2 is removed as a brine s105 containing impurities such as salt and the rest. About 1/2 is produced as desalinated production water s102 (industrial water). That is, the industrial water of the production water s102 is produced with a capacity of about 1/2 of seawater plus about 1/4 of sewage.

On the other hand, the brine s105 in which the salt concentration including impurities such as the salt removed by the medium pressure RO membrane 105 is concentrated to about twice that of the mixed water s103 is removed from the medium pressure RO membrane 105. That is, the brine s105 is drained with a capacity of about 1/2 of seawater plus about 1/4 of sewage.
The pressure energy of the brine s105 is recovered as rotational energy by the power recovery device 106 and used as a power source (energy source) for sending pressure to the intermediate pressure RO membrane 105 of a part of the mixed water s103 that bypasses the pump p104. It is done.

As another conventional desalination system, there is a desalination system S200 shown in FIG.
The desalination system S200 is configured such that the sewage concentrated water s104 in the desalination system S100 of FIG. 5 is not sent to the stirring tank 204, and sewage desalination and seawater desalination are independently configured.

In the desalination system S200, seawater having a high salinity concentration in the agitation tank 204 is not diluted with the water supplied from the sewage (the concentrated water s104 of the sewage in FIG. 5), so the salinity concentration is about 3 to 4% and the high pressure is about 6 A high-pressure RO membrane 205 of ˜8 MPa is used.
Since the other configuration is the same as that of the desalination system S100 of FIG. 5, the components of the desalination system S100 are denoted by reference numerals in the 200s and detailed description thereof is omitted.

In the desalination system S200, sewage passes through the low-pressure RO membrane 202 to be desalinated, and industrial water of the production water s201 that is about half of the sewage is obtained. On the other hand, seawater permeates through the high-pressure RO membrane 205 to be desalinated, and drinking water of the production water s202 that is half the amount of seawater is obtained.
The conventional desalination system S100 (see FIG. 5) has the following advantages over the desalination system S200 (see FIG. 6).

First, in the desalination system S100 of FIG. 5, since the waste water (concentrated water s104) removed in the process of producing the production water s101 from the sewage is used in the process of producing the production water s102 from the seawater, There is an advantage that the amount of production water from can be increased.
Specifically, when wastewater from the sewage (concentrated water s104) is not used, the production water from seawater has a capacity of about 1/2 that of seawater, but the volume of the sewage is increased to about 1/2. Therefore, a large amount of industrial water can be taken from the production water s102.

  Secondly, seawater (salt concentration of about 3 to 4%) is added with concentrated water s104 (salt concentration of about 0.2%) in the sewage low-pressure RO membrane 102, so that seawater is diluted and the salinity concentration decreases. . Therefore, when wastewater from the sewage (concentrated water s104) is not used, seawater has a high salinity, so a high-pressure RO membrane was necessary, but it was diluted with the concentrated water s104. 105, and the power of the pump p104 can be reduced as compared with the case of the high-pressure RO membrane.

The permeation pressure of the medium pressure RO membrane is about 3 to 5 MPa, whereas the permeation pressure of the high pressure RO membrane is about 6 to 8 MPa. Requires great power (energy).
In addition, there exists patent document 1 as a prior art document which concerns on this application.

Japanese Patent No. 4,481,345

Incidentally, the conventional desalination system S100 shown in FIG. 5 has the following problems.
First, although demand for drinking water is generally large, in order to mix a part of sewage (concentrated water s104) in the process of desalinating seawater, it is not possible to produce drinking water from seawater.
Secondly, the effect of adding sewage to the process of desalinating seawater is reduced when the supply amount of seawater is large even though the supply amount of seawater is usually large compared to the supply amount of sewage. To do.

  Specifically, when the supply amount of seawater is large, even if a part of the sewage is added to the process of desalinating seawater, the relative amount to seawater is small, so the salinity concentration does not decrease and the water is desalinated. The effect of reducing the permeation pressure to the RO membrane (corresponding to the medium-pressure RO membrane 105 in FIG. 5) decreases. As a result, the power (energy) reduction effect for obtaining the permeation pressure of the RO membrane is reduced. In addition, the water increase effect of the production water s102 is also reduced.

  Third, although the power recovery device 106 is more efficient at higher pressures, the power recovery device 106 cannot be operated where the efficiency is higher because the intermediate pressure RO membrane 105 is used. Therefore, it is difficult to obtain a high energy recovery rate.

  Fourth, since different reverse osmosis membranes for the low pressure RO membrane 102 and the intermediate pressure RO membrane 105 are used, it is difficult to say that the maintainability is good.

  In view of the above situation, an object of the present invention is to provide a seawater desalination system that can produce drinking water from seawater, increase industrial water, and reduce water production costs.

  In order to achieve the above object, a seawater desalination system according to the present invention is a seawater desalination system for obtaining industrial water and drinking water from seawater and sewage, and removes activated sludge by permeating the sewage. A purification device that purifies the water, a permeated water that has permeated through the purification device, and a first RO membrane that generates industrial water while the salt content is contained and removed in the first concentrated water; The UF membrane that removes particles in the seawater and the treated water that has passed through the UF membrane are permeated, and the salt content of the treated water is contained in the second concentrated water and removed, and the drinking water is generated. A stirring device in which the second RO membrane removed by the second RO membrane, the second concentrated water removed by the second RO membrane, and the first concentrated water removed by the first RO membrane are sent and stirred; The mixed liquid stirred by the stirrer is permeated and the salt content is third. A third RO membrane that is contained in the concentrated water and removed and generates industrial water, a first power recovery device that recovers the pressure energy of the second concentrated water, and a pressure energy of the third concentrated water And at least one of the second power recovery devices to be recovered.

  According to the seawater desalination system of the present invention, it is possible to produce drinking water from seawater, increase industrial water, and realize a seawater desalination system with low water production costs.

It is a notional block diagram of the desalination system of Embodiment 1 which concerns on this invention. It is a notional block diagram which shows the desalination system of Embodiment 2. FIG. It is a notional block diagram which shows the desalination system of the modification 1. FIG. It is a notional block diagram which shows the desalination system of the modification 2. FIG. It is a notional block diagram which shows the conventional desalination system. It is a notional block diagram which shows the other conventional desalination system.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
<< Embodiment 1 >>
FIG. 1 is a conceptual configuration diagram of a desalination system according to Embodiment 1 of the present invention.
The desalination system S of the first embodiment includes an MBR (Membrane Bioreactor) 1 that removes activated sludge from sewage and purifies it in order to produce industrial water s1 from sewage, and salt and ions contained in the sewage. And a low pressure RO membrane (Reverse Osmosis Membrane) 2 for removing impurities and desalinating.

MBR1 performs solid-liquid separation and removes activated sludge (such as solids and bacteria) from sewage and purifies it.
The RO membrane (reverse osmosis membrane) is a semipermeable membrane that allows water to pass through but does not allow low-molecular substances such as salt or ions to pass through. The low-pressure RO membrane 2 is a low-pressure RO membrane that removes salt and the like at a relatively low permeation pressure of about 1 to 2 MPa (megapascal) because the sewage has a low salinity concentration of about 0.1%.

In addition, the desalination system S has a UF membrane (Ultrafiltration Membrane) 3 that removes particles contained in seawater and impurities such as salt and ions contained in seawater in order to produce drinking water s2 from seawater. And a high-pressure RO membrane 4 to be removed and desalinated.
The UF membrane (ultrafiltration membrane) 3 performs molecular level sieving according to the pore size of the membrane and the molecular size of the substance to be removed in seawater, and removes the particles to be removed.
The high-pressure RO membrane 4 is a high-pressure RO membrane that removes salt and the like with a relatively high permeation pressure and about 6 to 8 MPa (megapascals) because the salt concentration of seawater is about 3 to 4%.

  Further, the desalination system S includes impurities such as salts and ions removed from the high-pressure RO membrane 4 in addition to the UF membrane 3 and the high-pressure RO membrane 4 in order to produce industrial water s3 from seawater. Stirring tank 5 for stirring seawater concentrated water s7 and sewage concentrated water s6 containing impurities such as salt and ions removed from low-pressure RO membrane 2, and salt and ions contained in the liquid mixture from stirring tank 5 And a high-pressure RO membrane 6 that is desalinated by removing impurities.

  The high-pressure RO membrane 6 has a seawater concentration s7 that is approximately twice the salinity of seawater (about 6-8% salinity) and a sewage that is almost twice the salinity (about 0.2% salinity). In order to desalinate the mixed solution with the sewage concentrated water s6, it is a high pressure RO membrane that removes salt and the like with a relatively high permeation pressure and about 6-8 MPa (megapascal). The seawater concentrated water s7 having a salinity concentration of about 6 to 8%, which is almost twice that of seawater, is diluted by adding the sewage concentrated water s6 (about 0.2% salinity concentration) to lower the salinity concentration.

Next, the process of making industrial water s1 from sewage in the desalination system S will be described.
The sewage is sent to the MBR1 by the pump p1, passes through the MBR1, and the activated sludge flocs and bacteria are removed from the sewage. The sewage MBR permeated water s5a that has passed through the MBR1 is sent to the low-pressure RO membrane 2 by the pump p2, and passes through the low-pressure RO membrane 2, thereby removing the concentrated sewage water s6 containing impurities such as salt and ions, and fresh water. And industrial water s1 is produced.

The industrial water s1 is obtained about 1/2 of the sewage, while the remainder of the sewage, that is, about 1/2 of the sewage is removed as the sewage concentrated water s6 containing impurities such as salt and ions.
Sewage concentrated water s6 concentrated to a salt concentration of about 0.2% containing impurities such as salt and ions removed by the low-pressure RO membrane 2 is sent from the low-pressure RO membrane 2 to the agitation tank 5.

Next, in the desalination system S, the process of making the drinking water s2 and industrial water s3 which are production water from seawater is demonstrated.
Seawater is sent to the UF membrane 3 by the pump p3, and the particles in the seawater are removed through the UF membrane 3. And the UF membrane permeation | transmission seawater s5b of the seawater from which particle | grains were removed with the UF membrane 3 is sent to the high pressure RO membrane 4 with the pump p4. The UF membrane-permeated seawater s5b that has passed through the UF membrane 3 passes through the high-pressure RO membrane 4, so that almost half is removed as seawater concentrate s7 containing impurities such as salt and ions, and the other half is desalinated. Produced as drinking water s2.

  On the other hand, the seawater concentrated water s7 having a salinity of about 6 to 8% having a volume of about 1/2 of the seawater removed by the high-pressure RO membrane 4 is 1/2 of the sewage removed by the low-pressure RO membrane 2 in the stirring tank 5. By stirring and diluting with about 2 sewage concentrated water s6 (salt concentration of about 0.2%), the salt concentration of about 6 to 8% is lowered.

The mixed liquid in which the salinity concentration of the seawater concentrated water s7 and the sewage concentrated water s6 is lowered is sent to the high pressure RO membrane 6 by the pump p5.
The mixed liquid of the sewage concentrated water s6 and the seawater concentrated water s7 from the agitation tank 5 passes through the high-pressure RO membrane 6, so that almost half is removed as brine s9 containing impurities such as salt and ions, and the remaining half. Is produced as desalinated industrial water s3.

According to the desalination system S of Embodiment 1, there exist the following effects.
1. Since the sewage is not mixed in the path for desalinating the seawater, the drinking water s2 with high demand can be produced.

2. The brine sewage concentrated water s6 removed in the sewage desalination process is added to the brine seawater concentrated s7 removed in the seawater desalination process to produce industrial water s3. The amount of industrial water produced by the entire system S can be increased.

For example, assume that the desalination system S of the first embodiment desalinates sewage with an amount of 2 (capacity 2) and seawater with an amount of 2 (capacity 2).
From the sewage of the amount 2, the industrial water s1 of the amount 1 is obtained by permeating the low-pressure RO membrane 2. On the other hand, a quantity 1 of drinking water s2 can be produced by passing a high pressure RO membrane 4 from the quantity 2 seawater. Further, the amount of seawater concentrated water s7 removed by the high-pressure RO membrane 4 and the amount of sewage concentrated water s6 removed by the low-pressure RO membrane 2 are stirred and permeated through the high-pressure RO membrane 6. One industrial water s3 is taken.
As a result, in the desalination system S of Embodiment 1, the drinking water s2 of quantity 1 and the industrial water s1, s3 of quantity 2 are obtained from the sewage of quantity 2 and the seawater of quantity 2.

When the sewage of the quantity 2 and the seawater of the quantity 2 of the same conditions are desalinated by the desalination system S100 of the conventional example 1 shown in FIG.
As shown in FIG. 5, the amount of sewage 2 is desalinated by the low-pressure RO membrane 102 to produce amount 1 of industrial water (product water s101). In addition, since the concentrated water s104 of the amount 1 of sewage is added to the seawater of the amount 2 in the agitation tank 104, the concentrated water s104 of the amount 2 of seawater and the amount 1 of sewage by passing through the intermediate pressure RO membrane 105. Industrial water (product water s102) in an amount of 1.5 of 1/2 of that is produced.
Therefore, in the desalination system S100 of Conventional Example 1, the amount of production water s101 and the amount of production water s102 of the amount 1 are totaled to obtain the amount of industrial water of amount 2.5.

  Therefore, when the desalination system S of Embodiment 1 is compared with the desalination system S100 of Conventional Example 1, the desalination system S of Embodiment 1 can obtain a large amount of 0.5 drinking water. In addition, in the desalination system S100 of FIG. 5, although only 2.5 amount of industrial water is obtained, the desalination system S of Embodiment 1 obtains the amount 1 drinking water in addition to the amount 2 industrial water. There is merit to be.

Further, when desalination is performed with the sewage of the amount 2 and the seawater of the amount 2 under the same conditions by the desalination system S200 shown in FIG.
As shown in FIG. 6, the amount 2 of sewage is desalinated by permeating through the low-pressure RO membrane 202 to obtain amount 1 of industrial water (product water s201). On the other hand, the amount 2 of seawater is desalinated by permeating the high-pressure RO membrane 205 to obtain amount 1 of drinking water (product water s202).

  Therefore, when using the amount 2 of sewage and the amount 2 of seawater, the desalination system S of the first embodiment is compared with the desalination system S of the first embodiment and the desalination system S200 of the conventional example 2. A lot of industrial water can be obtained.

3. In the desalination system S (see FIG. 1), for example, by stopping or adjusting the use of the sewage concentrated water s6, it is possible to flexibly cope with fluctuations in demand for industrial water. Therefore, if necessary, industrial water can be produced, and the demand for industrial water can be accommodated.

4). In the desalination system S, since the seawater concentrated water s7 having a salinity of about 6 to 8% is diluted with the sewage concentrated water s6 having a salinity of about 0.2% in the stirring tank 5, the salinity is lowered. Therefore, it is possible to use the high pressure RO membrane 6 of the same type as the high pressure RO membrane 4 on the downstream side of the seawater concentrated water s7.

  Since it is necessary to use a high-pressure RO membrane as the salinity concentration increases, a higher-pressure power source is required as the salinity concentration increases. Therefore, in the case of seawater concentrated water s7 having a salinity of about 6 to 8%, it is necessary to use an ultra-high pressure RO membrane, and a power source that outputs ultra-high pressure is required. Then, since the seawater concentrated water s7 having a salinity of about 6 to 8% is diluted with the sewage concentrated water s6 having a salinity of about 0.2%, a high-pressure RO membrane can be used, and power can be reduced.

5). Moreover, since the high-pressure RO membranes 4 and 6 are the same type, maintenance is easy and maintenance is good. Therefore, the merit in the maintenance management of the desalination system S is great.

<< Embodiment 2 >>
FIG. 2 is a conceptual configuration diagram illustrating a desalination system according to the second embodiment.
The desalination system 2S of the second embodiment is configured such that the low pressure RO membrane 2 of the desalination system S of the first embodiment is omitted (not installed). Since the other configuration is the same as that of the desalination system S of the first embodiment, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the desalination system 2S, the sewage is sent to the MBR1 by the pump p1, passes through the MBR1, and the activated sludge flocs and bacteria are removed from the sewage. Then, the MBR permeated water s22 that has passed through the MBR1 is sent to the agitation tank 5. In the agitation tank 5, the seawater concentrated water s7 and the MBR permeated water s22 that have permeated the UF membrane 3 and removed by the high-pressure RO membrane 4 are agitated, and then fed to the high-pressure RO membrane 6 by the pump p5.

Here, the seawater concentrated water s7 having a salinity of about 6 to 8% is diluted with the MBR permeated water s22 having a salinity of about 0.1% in the stirring tank 5, and the salinity is lowered.
The mixed liquid of the seawater concentrated water s7 and the MBR permeated water s22 is pressurized by the pump p5 and passes through the high-pressure RO membrane 6, so that half is removed as the brine s23 containing impurities such as salt and ions, and the other half. Is produced as desalinated industrial water s21.

According to the second embodiment, since the low-pressure RO membrane 2 of the first embodiment is not installed, the manufacturing and installation costs of the low-pressure RO membrane 2 are not required, and the cost can be reduced.
Further, since the RO membrane (reverse osmosis membrane) becomes the same type of high-pressure RO membranes 4 and 6, maintenance is easy and the maintainability is further improved. Therefore, the maintainability becomes better.
In addition, the effect of the desalination system S of Embodiment 1 is show | played similarly.

<< Modification 1 >>
FIG. 3 is a conceptual configuration diagram illustrating a desalination system according to the first modification.
The desalination system 3S according to the first modification is configured to recycle power by providing power recovery devices 34 and 36 downstream of the removal flow of the high-pressure RO membranes 4 and 6 of the desalination system S according to the first embodiment. It is.
Since the configuration other than this is the same as the configuration of the desalination system S of the first embodiment, the same components are denoted by the same reference numerals and detailed description thereof is omitted.

In the desalination system 3S, the seawater concentrated water s7 removed by the high-pressure RO membrane 4 is pressurized to a high pressure by the pump p4, and therefore has high pressure energy.
Therefore, in the desalination system 3S, a power recovery device 34 is provided in the flow path of the seawater concentrated water s7 from the high-pressure RO membrane 4.

  The power recovery device 34 recovers the pressure energy of the seawater concentrated water s7 removed by the high-pressure RO membrane 4 as rotational energy, and uses it as power for the UF membrane-permeated seawater s31 that passes through the UF membrane 3 and flows around the pump p4. And the UF membrane permeated seawater s31 is used as power for pumping to the high pressure RO membrane 4.

Similarly, since the brine (seawater concentrated water) s9 removed by the high-pressure RO membrane 6 is pressurized to a high pressure by the pump p5, it has high pressure energy.
Therefore, in the desalination system 3S, a power recovery device 36 is provided in the flow path of brine (seawater concentrated water) s9 from the high-pressure RO membrane 6.

  The power recovery device 36 recovers the pressure energy of the brine (seawater concentrated water) s9 as rotational energy, applies it as power to the stirring tank passing water s32 that flows around the pump p5 after being mixed in the stirring tank 5 and stirred. The tank passing water s32 is used as power for pumping to the high pressure RO membrane 6.

According to the desalination system 3S of the first modification, the power recovery device 34 is provided in the flow path downstream of the high-pressure seawater concentrated water s7 of the removal flow from the high-pressure RO membrane 4, and the removal flow from the high-pressure RO membrane 6 is also provided. A power recovery device 36 is provided in the flow path downstream of the high-pressure brine (seawater concentrated water) s9.
Since the power recovery devices 34 and 36 can recover the pressure energy of the high-pressure seawater concentrated water s7 and brine s9, respectively, as rotational energy, they can be used with high efficiency. Therefore, the power (energy) of the desalination system S of Embodiment 1 can be reduced, and energy saving can be achieved.

<< Modification 2 >>
FIG. 4 is a conceptual configuration diagram illustrating a desalination system according to the second modification.
The desalination system 4S according to the second modification is similar to the desalination system 2S according to the second embodiment, in the same manner as the first modification, in the downstream of the removal flow (s41, s42) of the high-pressure RO membranes 4 and 6; Is provided.
Since other configurations are the same as the desalination system 2S of the second embodiment, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the desalination system 4S of variant 2, the power recovery devices 44 and 46 recover the pressure energy of the seawater concentrated water s7 and brine s23 as rotational energy, respectively, and the pumping force of the UF membrane permeated seawater s41 and the stirring tank passing water s42, respectively. Can be obtained.

  According to the desalination system 3S of the modification 2, the power (energy) of the desalination system 2S of the embodiment 2 can be reduced, and energy saving can be achieved.

<< Other Embodiments >>
In the first modification, the case where both of the power recovery devices 34 and 36 are provided is illustrated, but any one of the power recovery devices 34 and 36 may be provided. Similarly, in the second modification, the case where both the power recovery devices 44 and 46 are provided is illustrated, but any one of the power recovery devices 44 and 46 may be provided.

Moreover, in the modification 1, although the power collect | recovered with the power recovery apparatuses 34 and 36 was illustrated as the pumping force of UF membrane permeation | transmission seawater s31 and stirring tank passage water s32, respectively, it utilized as power other than this. Also good. Similarly, in the modified example 2, the power recovered by the power recovery devices 44 and 46 is exemplified as the pumping force of the UF membrane permeated seawater s41 and the stirring tank passing water s42, but the power different from that illustrated It may be used as
In the above-described embodiments and modifications, MBR is exemplified as a purification device that removes and purifies activated sludge from sewage, but purification devices other than MBR1, such as natural precipitation, sand filtration, and disinfection, may be applied. Absent.
In addition, the numerical values used in the description of the above-described embodiments and modifications are examples, and are not limited to these numerical values.

1 MBR (Purification device)
2 Low pressure RO membrane (first RO membrane)
3 UF membrane 4 High-pressure RO membrane (second RO membrane)
5 Stirring tank (stirring device)
6 High-pressure RO membrane (third RO membrane)
34 Power recovery device (first power recovery device)
36 Power recovery device (second power recovery device)
3S desalination system (seawater desalination system)
s1, s3 Industrial water s2 Drinking water s5b UF membrane permeated seawater (treated water)
s6 Sewage concentrated water (first concentrated water)
s7 Seawater concentrated water (second concentrated water)
s9 brine (third concentrated water)

Claims (1)

A seawater desalination system for obtaining industrial water and drinking water from seawater and sewage,
A purification device for removing activated sludge by permeating the sewage and purifying,
A first RO membrane that permeates the permeated water that has passed through the purification device, the salt content of which is contained and removed in the first concentrated water, and generates industrial water;
A UF membrane that permeates the seawater to remove particles in the seawater;
A second RO membrane that allows the treated water that has permeated through the UF membrane to pass through, the salt content of the treated water is contained and removed in the second concentrated water, and generates drinking water;
A stirrer in which the second concentrated water removed by the second RO membrane and the first concentrated water removed by the first RO membrane are sent and stirred;
A third RO membrane that permeates the mixed solution stirred by the stirring device and removes the salt contained in the third concentrated water and generates industrial water;
And at least one of a first power recovery device that recovers pressure energy of the second concentrated water and a second power recovery device that recovers pressure energy of the third concentrated water. Seawater desalination system.

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