JP2021094519A - Concentration system - Google Patents

Abstract

To provide a concentration system that suppresses membrane blockage in semipermeable membrane modules and reverse osmosis membrane modules used for brine concentration (BC).SOLUTION: There is provided a concentration system including: a reverse osmosis module 2 that separates and recovers water from undiluted liquid through a reverse osmosis membrane 20 and discharges a first target liquid that is a concentrated solution; and a semipermeable membrane module 1 having a semipermeable membrane 10 and a first chamber 11 and a second chamber 12 separated by the semipermeable membrane 10, and configured such that water contained in the first target liquid in the first chamber 11 is transferred to the second target liquid in the second chamber 12 through the semipermeable membrane 10 by flowing the first target liquid into the first chamber 11 and the second target liquid into the second chamber 12, and the concentrated solution is discharged from the first chamber 11 and the diluted liquid is discharged from the second chamber 12. The system further includes a purification device 3 that removes at least one of a hard component and a turbid component from at least one of the first target liquid, the concentrated liquid, the second target liquid, and the diluted liquid.SELECTED DRAWING: Figure 1

Description

The present invention relates to a concentration system.

For example, for the purpose of reducing the energy required for desalination using the reverse osmosis (RO) method, a high-pressure target liquid is flowed through the first chamber of the semipermeable membrane module, and a low-pressure target is flowed into the second chamber. By flowing the liquid and transferring the water contained in the target liquid in the first chamber to the target liquid in the second chamber via the semipermeable membrane, the concentrated target liquid is discharged from the first chamber and the second chamber is discharged. A membrane separation method (semipermeable membrane) for discharging the target liquid diluted from the above has been studied (see, for example, Patent Document 1: Japanese Patent Application Laid-Open No. 2018-1110).

Further, the concentrated liquid discharged from the RO module is flowed to the first chamber of the semipermeable membrane module that can be operated at a higher pressure, and the concentrated liquid is further subjected to the above-mentioned brine concentration (BC) under ultra-high pressure conditions as compared with the RO method. Concentration systems for concentrating are also being considered.

Japanese Unexamined Patent Publication No. 2018-1110

When the undiluted solution such as seawater supplied to the RO module contains scale components (hard components such as bicarbonate), the scale components are concentrated on the surface of the semipermeable membrane when concentrated by the RO module. It precipitates as scale (carbonate, etc.), causing problems such as clogging of the semipermeable membrane. Therefore, when the stock solution contains a scale component, the stock solution is subjected to a treatment for suppressing or reducing the precipitation of the scale component by adding a scale inhibitor or the like to the extent that the scale does not precipitate in the RO module. ..

Here, the level of suppressing or reducing the precipitation of the scale component (such as the amount of the scale inhibitor added) may be a level at which the scale does not precipitate due to concentration in the RO module, and the scale component is completely removed from the stock solution. There is no need. Therefore, the concentrated liquid discharged from the RO module may have a solution composition at a level at which scale is easily generated when the concentration is further increased.

Therefore, in a concentration system in which a brine concentration (BC) is combined after the RO module to further concentrate, the semipermeable membrane used for BC when the concentrate discharged from the RO module is further concentrated by BC. Scale may occur in the membrane module. Further, in the case of BC, when the water temperature or pH of the liquid fluctuates, there is a possibility that scale (hard component) is precipitated.

In the semipermeable membrane module used for BC, if scale is deposited, problems such as membrane clogging (clogging) may occur.

In addition, the undiluted solution such as seawater supplied to the RO module may contain turbid components (organic substances, microorganisms, etc.). The turbid component is also usually subjected to a reduction treatment of the turbid component in the stock solution to the extent that the film is not blocked by the turbid component in the RO module. However, when the concentrated liquid discharged from the RO module is further concentrated by BC, the semipermeable membrane module used for BC may have the same problem as the scale component due to the high concentration of the turbid component. There is.

Here, as shown in FIG. 2, the pressure of the target liquid (concentrated liquid concentrated by BC) discharged from the first chamber 11 of the semipermeable membrane module 1 is reduced to reduce the pressure of the second semipermeable membrane module 1. When the target liquid (diluted liquid diluted by BC) that flows into the chamber 12 and is discharged from the second chamber 12 of the semipermeable membrane module 1 is reused as at least a part of the stock solution of the target liquid, this is used. Such problems will continue to occur throughout the enrichment system.

Therefore, according to the present invention, in a concentration system in which the concentrated stock solution discharged from the back permeation (RO) module is further concentrated by brine concentration (BC), the concentrated solution discharged from the first chamber 11 of the semipermeable membrane module 1 is used. The diluted solution that reduces the pressure and flows into the second chamber 12 of the semipermeable membrane module 1 and is discharged from the second chamber 12 of the semipermeable membrane module 1 is reused as at least a part of the stock solution of the target solution. In some cases, the purpose is to suppress membrane blockage in the semipermeable membrane module and RO module used for BC.

(1) A reverse osmosis module that separates and recovers water from a stock solution that has been pressurized to a predetermined pressure via a reverse osmosis membrane, and discharges the concentrated first target solution, which is the stock solution.
It has a semipermeable membrane and a first chamber and a second chamber partitioned by the semipermeable membrane, the first target liquid is flowed into the first chamber at a predetermined pressure, and the second target liquid is flown into the predetermined chamber. By flowing the liquid into the second chamber at a pressure lower than the pressure of the above, the water contained in the first target liquid in the first chamber is transferred to the second target liquid in the second chamber via the semipermeable membrane. A semipermeable membrane module, which discharges the concentrated liquid from the first chamber and discharges the diluted liquid from the second chamber, is provided.
At least a part of the concentrated liquid discharged from the first chamber is flowed into the second chamber as the second target liquid.
The diluent is a concentration system that is reused as at least part of the stock solution.
A concentration system further comprising a purification device for removing at least one of a hard component and a turbid component from at least one of the first target liquid, the concentrated liquid, the second target liquid, and the diluted liquid.

(2) The concentration system according to (1), wherein the purification device removes at least one of a hard component and a turbid component from the concentrate.

(3) The purification device removes turbid components and hard components from at least one of the first target liquid, the concentrated liquid, the second target liquid, and the diluted liquid in this order, (1) or The concentration system according to (2).

According to the present invention, in a concentration system in which the concentrated stock solution discharged from the back permeation (RO) module is further concentrated by brine concentration (BC), the concentrated solution discharged from the first chamber 11 of the semipermeable membrane module 1 is used. The diluted solution that reduces the pressure and flows into the second chamber 12 of the semipermeable membrane module 1 and is discharged from the second chamber 12 of the semipermeable membrane module 1 is reused as at least a part of the stock solution of the target solution. In some cases, membrane occlusion and the like in the semipermeable membrane module and RO module used for BC can be suppressed.

It is a schematic diagram which shows the enrichment system of an embodiment. It is a schematic diagram which shows the conventional concentration system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals represent the same parts or equivalent parts. Further, the dimensional relationships such as length, width, thickness, and depth are appropriately changed for the purpose of clarifying and simplifying the drawings, and do not represent the actual dimensional relationships.

<Embodiment 1>
With reference to FIG. 1, the concentration system of the present embodiment mainly includes a reverse osmosis module 2, a semipermeable membrane module 1, and a purification device 3.

In the reverse osmosis module 2, water is separated and recovered from the undiluted solution pressurized to a predetermined pressure via the reverse osmosis membrane 20, and the first target solution (concentrated undiluted solution) which is the concentrated undiluted solution is discharged.
The semipermeable membrane module 1 has a semipermeable membrane 10 and a first chamber 11 and a second chamber 12 partitioned by the semipermeable membrane, and the first target liquid is allowed to flow into the first chamber 11 at a predetermined pressure. By flowing the second target liquid through the second chamber 12 at a pressure lower than a predetermined pressure (pressure of the first target liquid), the water contained in the first target liquid in the first chamber 11 is semipermeable membrane. The liquid is transferred to the second target liquid in the second chamber 12 through the chamber 12, the concentrated liquid is discharged from the first chamber 11, and the diluted liquid is discharged from the second chamber 12.
At least a part of the concentrated liquid discharged from the first chamber 11 is flowed to the second chamber 12 as the second target liquid, and the diluted liquid discharged from the second chamber 12 is re-used as at least a part of the stock solution. It will be used.
In the purification device 3, at least one of the hard component and the turbid component is removed from at least one of the first target liquid, the concentrated liquid, the second target liquid, and the diluted liquid.

In the purification device 3, "removing" at least one of the hard component and the turbid component does not necessarily mean that at least one of the hard component and the turbid component is completely removed, and the hard component and the turbid component do not necessarily have to be completely removed. At least a part of at least one of the components may be removed. That is, it suffices if the amount of at least one of the hard component and the turbid component can be reduced.

Hereinafter, the details of the enrichment system of the present embodiment will be described.

[Reverse osmosis module]
The enrichment system of this embodiment includes a high pressure pump 2a on the upstream side of the reverse osmosis (RO) module 2. The high-pressure pump 2a boosts the stock solution to a predetermined pressure and supplies it to the first chamber 21 of the RO module 2. The RO module 2 separates water (permeated water) from the undiluted solution pressurized to a predetermined pressure to the second chamber 22 side via the reverse osmosis (RO) membrane 20 to obtain a concentrated undiluted solution (concentrated undiluted solution). The first target solution) is discharged from the first chamber 21, and the water is discharged from the second chamber 22.

In the present specification, the "stock solution" is not particularly limited as long as it is a liquid containing water supplied to the RO module 2, and may be either a solution or a suspension. Examples of the undiluted solution include seawater, river water, brackish water, wastewater and the like. Examples of wastewater include industrial wastewater, domestic wastewater, oil field or gas field wastewater, and the like.

A pretreatment device (not shown) may be provided on the upstream side of the high-pressure pump 2a in order to remove turbid substances (fine particles, microorganisms, scale components, etc.) contained in the undiluted solution. Examples of the pretreatment device include a sand filtration device, a filtration device using a UF (Ultrafiltration) membrane, an MF (Microfiltration) membrane, etc., chlorine, sodium hypochlorite, a flocculant, and scale. Examples include an addition device such as an inhibitor and a pH adjustment device. The scale inhibitor is an additive having an action of preventing or suppressing the precipitation of scale components in the liquid as scale. Examples of the anti-scale agent include compounds such as polyphosphoric acid-based, phosphonic acid-based, phosphinic acid-based, and polycarboxylic acid-based compounds.

In the present embodiment, the semipermeable membrane module 1 is connected to the downstream side of the RO module 2 (first chamber 21). Since the concentrated stock solution discharged from the first chamber 21 of the RO module 2 has a high pressure, it is sent to the semipermeable membrane module 1 side by the pressure. That is, the concentrated stock solution discharged from the first chamber 21 of the RO module 2 is the first target liquid supplied to the first chamber 11 of the semipermeable membrane module 1.

[Semipermeable membrane module]
The semipermeable membrane module 1 has a semipermeable membrane 10 and a first chamber 11 and a second chamber 12 partitioned by the semipermeable membrane 10.

The first target liquid (concentrated stock solution) flows into the first chamber 11 at a predetermined pressure, and the second target liquid flows into the second chamber 12 at a pressure lower than the predetermined pressure. As a result, the water contained in the first target liquid in the first chamber 11 is transferred to the second target liquid in the second chamber 12 via the semipermeable membrane 10, and is concentrated (concentrated) from the first chamber 11. The first target liquid) is discharged, and the diluted liquid (diluted second target liquid) is discharged from the second chamber 12.

Here, in the present embodiment, at least a part of the concentrated liquid discharged from the first chamber is flowed to the second chamber as the second target liquid. In FIG. 1, at least a part of the concentrated liquid discharged from the first chamber is flowed to the second chamber as the second target liquid via the purification device 3 described later, but the position of the purification device 3 Is not limited to this position.

In the case of FIG. 1, since the target liquids flowing into the first chamber 11 and the second chamber 12 of the semipermeable membrane module 1 are the same liquid, they have basically the same osmotic pressure. Therefore, unlike the RO method, a high pressure for causing reverse osmosis against the high osmotic pressure difference between the target liquid (high osmotic liquid) and fresh water is not required, and pressure is applied at a relatively low pressure. Membrane separation of the target solution can be performed (some target solutions can be diluted and some other target solutions can be concentrated).

However, in the present embodiment, the second target liquid supplied to the second chamber 12 of the semipermeable membrane module 1 may include a liquid other than the first target liquid supplied to the first chamber 11.

In this case, even if the concentration is different between the first target liquid flowing in the first chamber 11 and the second target liquid flowing in the second chamber 12, the osmotic pressure difference (absolute value) is supplied to the first chamber 11. In theory, membrane separation by BC is feasible if the pressure is lower than the pressure of the first target liquid. The difference between the osmotic pressure of the first target liquid flowing into the first chamber 11 (high pressure side) and the osmotic pressure of the second target liquid supplied to the second chamber 12 (low pressure side) is supplied to the first chamber 11. It is preferably 30% or less of the predetermined pressure of the first target liquid.

In the present embodiment, the diluent discharged from the second chamber 12 of the semipermeable membrane module 1 is reused as at least a part of the stock solution. As a result, the liquid discharged to the outside from the concentration system is discharged from the first chamber 11 of the semipermeable membrane module 1 in the most concentrated state and the second chamber 22 of the RO module 2. Only water. In this case, the concentrate is further treated and is not discharged into the external environment such as the ocean or river as it is, but only water is discharged into the external environment. Therefore, the second chamber of the semipermeable membrane module 1 is discharged. Unlike the diluted solution discharged from No. 12, the solution in a state of being more concentrated than the undiluted solution is not discharged into the external environment, and adverse effects on the environment can be prevented.

The BC process may be a one-stage process using one semipermeable membrane module 1 as shown in FIG. 1, but is a multi-stage process using a plurality of semipermeable membrane modules. May be good.

In the brine concentration (BC), which is the membrane separation process in the semipermeable membrane module 1, in order to transfer water from the first chamber 11 to the second chamber 12 via the semipermeable membrane 10 of the semipermeable membrane module 1. , The pressure of the first target liquid supplied to the first chamber 11 needs to be larger than the osmotic pressure difference between the first target liquid and the second target liquid flowing on both sides of the semipermeable membrane 10. Therefore, in order to highly concentrate the first target liquid in one step (one semipermeable membrane module), it is necessary to supply it at a correspondingly high pressure, and the energy cost for operating the pump is high. There are disadvantages such as an increase in. Therefore, BC may be carried out by a multi-step process using a plurality of semipermeable membrane modules for the purpose of stepwise concentration step and reducing the pressure required for BC. BC by such a multi-step process is disclosed in, for example, Japanese Patent Application Laid-Open No. 2018-069198.

Examples of the semipermeable membrane include a semipermeable membrane called a reverse osmosis (RO) membrane, a forward osmosis (FO) membrane, and a nanofiltration (NF) membrane. When a reverse osmosis membrane, a forward osmosis membrane, or a nanofiltration membrane is used as the semipermeable membrane, the pressure of the first target liquid supplied to the first chamber 11 is preferably 6 to 10 MPa.

Usually, the pore diameters of the RO membrane and the FO membrane are about 2 nm or less, and the pore diameter of the UF membrane is about 2 to 100 nm. The NF membrane has a relatively low inhibition rate of ions and salts among the RO membranes, and the pore size of the NF membrane is usually about 1 to 2 nm. When an RO membrane, an FO membrane, or an NF membrane is used as the semipermeable membrane, the salt removal rate of the RO membrane, the FO membrane, or the NF membrane is preferably 90% or more.

The material constituting the semipermeable membrane is not particularly limited, and examples thereof include a cellulosic resin, a polysulfone resin, and a polyamide resin. The semipermeable membrane is preferably composed of a material containing at least one of a cellulosic resin and a polysulfone resin.

The cellulosic resin is preferably a cellulosic acetate resin. Cellulose acetate-based resins are resistant to chlorine, which is a bactericidal agent, and have the characteristic of being able to suppress the growth of microorganisms. The cellulose acetate-based resin is preferably cellulose acetate, and more preferably tricellulose triacetate from the viewpoint of durability.

The polysulfone-based resin is preferably a polyether sulfone-based resin. The polyether sulfone-based resin is preferably a sulfonated polyether sulfone.

The shape of the semipermeable membrane 10 (and the reverse osmosis membrane 20 described above) is not particularly limited, and examples thereof include a flat membrane and a hollow fiber membrane. In FIG. 1, the semipermeable membrane 10 is a simplified drawing of the flat membrane, but the shape is not particularly limited to such a shape. The hollow fiber membrane (hollow fiber type semipermeable membrane) is advantageous in that the membrane area per module can be increased and the permeation efficiency can be improved as compared with a spiral type semipermeable membrane or the like.

The form of the semipermeable membrane module 1 (and the reverse osmosis module 2 described above) is not particularly limited, but when a hollow fiber membrane is used, a module in which the hollow fiber membrane is arranged straight or a hollow fiber membrane is used as a core tube. A cross-wind type module wrapped around the membrane can be mentioned. When a flat film is used, examples thereof include a laminated module in which flat films are stacked, and a spiral module in which the flat film is wound around a core tube in an envelope shape.

As an example of a specific hollow fiber membrane, there is a single-layer structure membrane which is entirely composed of a cellulosic resin. However, the single-layer structure referred to here does not have to be a uniform film as a whole, and has, for example, a dense layer in the vicinity of the outer peripheral surface as disclosed in Japanese Patent Application Laid-Open No. 2012-115835. It is preferable that the dense layer is a separation active layer that substantially defines the pore size of the hollow fiber membrane.

As another specific example of the hollow fiber membrane, a two-layer structure having a dense layer made of a polyphenylene resin (for example, sulfonated polyether sulfone) on the outer peripheral surface of a support layer (for example, a layer made of polyphenylene oxide). Membrane is mentioned. Further, as another example, a film having a two-layer structure having a dense layer made of a polyamide resin on the outer peripheral surface of a support layer (for example, a layer made of polysulfone or polyethersulfone) can be mentioned.

In a semipermeable membrane module using a hollow fiber membrane, the outside of the hollow fiber membrane is usually the first chamber. This is because even if the fluid flowing inside the hollow fiber membrane (hollow portion) is pressurized, the pressure loss becomes large and it is difficult for the pressurization to work sufficiently.

[Purification device]
In the purification device 3, at least one of the hard component and the turbid component is removed from at least one of the first target liquid, the concentrated liquid, the second target liquid, and the diluted liquid.
As a result, in the concentration system in which the concentrated stock solution discharged from the RO module is further concentrated by BC, the pressure of the concentrated solution discharged from the first chamber 11 of the semipermeable membrane module 1 is reduced to reduce the pressure of the semipermeable membrane module 1 first. The semipermeable membrane module and the semipermeable membrane module used for BC when the diluted solution that flows into the two chambers 12 and is discharged from the second chamber 12 of the semipermeable membrane module 1 is reused as at least a part of the stock solution of the target solution. It is possible to suppress membrane blockage in the RO module.

The removal of the hard component is carried out by, for example, a water softening device described later.
The removal of the turbid component is carried out by, for example, a turbidity removing device described later.
That is, the purification device 3 includes, for example, these water softening devices, turbidity removing devices, and the like.

In the purification device 3, either the hard component or the turbid component may be removed, and both the hard component and the turbid component may be removed.
That is, the purification device 3 may include only the water softening device, may include only the turbidity removing device, or may include both the water softening device and the turbidity removing device.

When both the hard component and the turbid component are removed from the concentrated stock solution by the purification device 3, the turbid component and the hard component are removed from the concentrated stock solution in this order and discharged as the first target solution. Is preferable. That is, when the purification device 3 includes both a water softening device and a turbidity removing device, it is preferable that the turbidity removing device and the turbidity removing device are provided in this order from the upstream side of the flow of the concentrated stock solution.
For the removal of hard components, for example, a membrane having finer pores such as a nanofiltration membrane is used, and membrane blockage is likely to occur. Therefore, it is better to remove the turbid component first to block the membrane when removing the hard component. This is because problems such as the above are unlikely to occur.

As shown in FIG. 1, the purifying device 3 preferably removes at least one of a hard component and a turbid component from the concentrated liquid discharged from the first chamber 11 of the semipermeable membrane module 1. That is, it is preferable that the purification device 3 is provided on the downstream side of the first chamber 11 of the semipermeable membrane module 1 and on the upstream side of the second chamber 12 of the semipermeable membrane module 1.
In this case, the other first target solution (concentrated stock solution), diluted solution, etc. is discharged from the semipermeable membrane module 1 rather than being purified (removing at least one of the hard component and the turbid component). The amount of processing by the purification device is smaller when the purification treatment is performed on the concentrated liquid. This has the advantage that the space required for the equipment is small and the initial investment cost is low.

Since the purifying device 3 often does not have high pressure resistance, the concentrated liquid having a high pressure discharged from the first chamber 11 of the semipermeable membrane module 1 is in a state where the pressure is lowered by, for example, the pressure lowering device 4. Is supplied to the purification device 3. Therefore, a pump 1a for sending the first target liquid to the second chamber 12 of the semipermeable membrane module 1 is provided in the flow path from the purification device 3 to the second chamber 12 of the semipermeable membrane module 1. May be good.
Examples of the pressure lowering device 4 include a flow dividing valve, a decompressor, an energy recovery device, and the like.

Examples of the energy recovery device include an electric energy recovery device that recovers energy as electricity using a turbine or the like, or a mechanical energy recovery device that mechanically recovers energy from a concentrated liquid.
As a mechanical energy recovery device, a power transmission type energy recovery device that recovers the pressure energy of the concentrate as power by using a turbocharger or a water wheel coaxially coupled to the drive shaft of a high-pressure pump is known. Has been done. Further, as another example of the mechanical energy recovery device, a pressure transfer type energy recovery device that directly recovers the pressure of the concentrated liquid such as a pressure converter (PX) can also be used. Such an energy recovery device is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-81913, Japanese Patent Application Laid-Open No. 1-1123605, and the like.

(Water softening device)
The water softening device is a device for obtaining a liquid in which the amount of hard components is reduced by removing hard components (polyvalent ions such as calcium ions and magnesium ions) from the concentrated stock solution discharged from RO module 1.

Examples of the water softening device include a filtration device using an NF (Nanofiltration) membrane, a processing device using an ion exchange resin, and the like. Such a water softening device is disclosed in, for example, Nagahisa Sato et al., "Water softening using a modified RO membrane", Membrane (MEMBRANE), 38 (6), 304-309, 2013 and the like.

It is preferable to carry out maintenance of the water softening device during the operation stop period of the concentration system. Examples of maintenance include chemical cleaning in the case of a filtration device using an NF film, and regeneration treatment of an ion exchange resin in the case of a processing device using an ion exchange resin.

(Muddy substance removal device)
The turbidity removing device is a device that obtains a liquid in which the amount of turbidity components is reduced by removing turbidity components (insoluble objects such as organic substances and microorganisms) from the concentrated stock solution discharged from RO module 1. ..

Examples of the turbidity removing device include a filtration device using a UF (Ultrafiltration) membrane.

It is preferable to carry out maintenance of the turbidity removing device during the operation stop period of the concentration system. Examples of maintenance include back pressure cleaning and chemical cleaning in the case of a filtration device using a UF membrane.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Semipermeable membrane module, 1a pump, 10 Semipermeable membrane, 11 1st chamber, 12 2nd chamber, 2 Reverse osmosis (RO) module, 2a High pressure pump, 20 Reverse osmosis (RO) membrane, 21 1st chamber, 22 Room 2, 3 Purifier, 4 Pressure reducer.

Claims (3)

A reverse osmosis module that separates and recovers water from a stock solution that has been pressurized to a predetermined pressure via a reverse osmosis membrane, and discharges the concentrated first target liquid that is the stock solution.
It has a semipermeable membrane and a first chamber and a second chamber partitioned by the semipermeable membrane, the first target liquid is flowed into the first chamber at a predetermined pressure, and the second target liquid is flown into the predetermined chamber. By flowing the liquid into the second chamber at a pressure lower than the pressure of the above, the water contained in the first target liquid in the first chamber is transferred to the second target liquid in the second chamber via the semipermeable membrane. A semipermeable membrane module, which discharges the concentrated liquid from the first chamber and discharges the diluted liquid from the second chamber, is provided.
At least a part of the concentrated liquid discharged from the first chamber is flowed into the second chamber as the second target liquid.
The diluent is a concentration system that is reused as at least part of the stock solution.
A concentration system further comprising a purification device for removing at least one of a hard component and a turbid component from at least one of the first target liquid, the concentrated liquid, the second target liquid, and the diluted liquid. The concentration system according to claim 1, wherein the purification device removes at least one of a hard component and a turbid component from the concentrate. The purifying device according to claim 1 or 2, wherein the purifying device removes a turbid component and a hard component from at least one of the first target liquid, the concentrated liquid, the second target liquid, and the diluted liquid in this order. Concentration system.

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