CN212832954U

CN212832954U - Concentration system

Info

Publication number: CN212832954U
Application number: CN202020212163.7U
Authority: CN
Inventors: 三浦佑己; 合田昌平; 中尾崇人
Original assignee: Toyobo Co Ltd
Current assignee: Dongyang Textile Mc Co ltd
Priority date: 2019-12-17
Filing date: 2020-02-25
Publication date: 2021-03-30
Anticipated expiration: 2030-02-25
Also published as: WO2021125002A1; JP2021094519A

Abstract

The utility model relates to a concentrated system, it possesses: a reverse osmosis module which separates and recovers water from the stock solution pressurized to a predetermined pressure through a reverse osmosis membrane and discharges a first target solution as a concentrated stock solution; a semipermeable membrane module comprising a semipermeable membrane, a first chamber and a second chamber partitioned by the semipermeable membrane, wherein a first object liquid is caused to flow into the first chamber at a predetermined pressure, a second object liquid is caused to flow into the second chamber at a pressure lower than the predetermined pressure, water contained in the first object liquid in the first chamber is transferred to the second object liquid in the second chamber through the semipermeable membrane, a concentrated liquid is discharged from the first chamber, a diluted liquid is discharged from the second chamber, at least a part of the concentrated liquid discharged from the first chamber is caused to flow into the second chamber as the second object liquid, and the diluted liquid is reused as at least a part of a stock solution.

Description

Concentration system

Technical Field

The utility model relates to a concentrated system.

Background

For example, the following membrane separation method (brine concentration) has been studied for the purpose of reducing the energy required for desalination of sea water by Reverse Osmosis (RO): a high-pressure target liquid is flowed through a first chamber of a semipermeable membrane module, a low-pressure target liquid is flowed through a second chamber, water contained in the target liquid in the first chamber is transferred to the target liquid in the second chamber through a semipermeable membrane, thereby discharging the concentrated target liquid from the first chamber, and discharging the diluted target liquid from the second chamber (see, for example, japanese patent application laid-open No. 2018-1110).

In addition, the following concentration systems were also investigated: the concentrate discharged from the RO module is flowed to the first chamber of the semipermeable membrane module operable at a higher pressure, and the concentrate is further concentrated under an ultrahigh pressure condition higher than that in the RO process by the above-mentioned Brine Concentration (BC).

If a raw liquid such as seawater supplied to the RO module contains scale components (hard components such as bicarbonate), the scale components are concentrated and deposited as scale (carbonate or the like) on the surface of the semipermeable membrane during concentration in the RO module, causing problems such as clogging of the semipermeable membrane. Therefore, when the raw liquid contains a scale component, the raw liquid is subjected to a treatment for suppressing or reducing the deposition of the scale component by adding a scale inhibitor or the like to such an extent that no scale is deposited in the RO module.

Here, the level of inhibition or reduction of the deposition of the scale component (the amount of the scale inhibitor added, etc.) is not required to be a level at which the scale is not deposited by the concentration in the RO module, and it is not necessary to completely remove the scale component from the raw liquid. There are therefore the following situations: if the concentration of the concentrate discharged from the RO module is further increased, the concentrate has a solution composition at such a level that scale is likely to be generated.

Therefore, in a concentration system in which Brine Concentration (BC) is combined after the RO module and the concentrate is further concentrated, when the concentrate discharged from the RO module is further concentrated by the BC, scale may be generated in the semipermeable membrane module used for the BC. Further, at BC, if the water temperature and pH of the liquid fluctuate, scale (hard component) may be deposited.

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

In addition, suspended matter components (organic matter, microorganisms, and the like) may be contained in a raw liquid such as seawater supplied to the RO module. The suspended matter component is usually subjected to a treatment for reducing the suspended matter component in the raw liquid to such an extent that the membrane is not occluded by the suspended matter component in the RO module. However, when the concentrate discharged from the RO module is further concentrated by the BC, the suspended matter component may reach a high concentration in the semipermeable membrane module used for the BC, and the same problem as the scale component may occur.

Here, as shown in fig. 2, when the target fluid (the concentrated fluid concentrated by BC) discharged from the first chamber 11 of the semipermeable membrane module 1 is caused to flow to the second chamber 12 of the semipermeable membrane module 1 by reducing the pressure, and the target fluid (the diluted fluid diluted by BC) discharged from the second chamber 12 of the semipermeable membrane module 1 is reused as at least a part of the original fluid of the target fluid, such a problem continues to occur throughout the entire concentration system.

SUMMERY OF THE UTILITY MODEL

Therefore, an object of the present invention is to suppress membrane clogging or the like in the semipermeable membrane module for BC and the RO module when the concentrated solution discharged from the Reverse Osmosis (RO) module is further concentrated by Brine Concentration (BC) in the concentration system, the concentrated solution discharged from the first chamber 11 of the semipermeable membrane module 1 is allowed to flow to the second chamber 12 of the semipermeable membrane module 1 by reducing the pressure, and the diluted solution discharged from the second chamber 12 of the semipermeable membrane module 1 is reused as at least a part of the raw solution of the target solution.

(1) A concentration system is provided with:

a reverse osmosis module which separates and recovers water from a raw liquid pressurized to a predetermined pressure by a reverse osmosis membrane and discharges a first target liquid which is the concentrated raw liquid;

a semipermeable membrane module having a semipermeable membrane and a first chamber and a second chamber partitioned by the semipermeable membrane, wherein the first target fluid is flowed into the first chamber at a predetermined pressure, and the second target fluid is flowed into the second chamber at a pressure lower than the predetermined pressure, whereby water contained in the first target fluid in the first chamber is transferred into the second target fluid in the second chamber through the semipermeable membrane, a concentrated fluid is discharged from the first chamber, and a diluted fluid is discharged from the second chamber,

flowing at least a portion of the concentrate discharged from the first chamber to a second chamber as the second object,

the diluent is reused as at least a portion of the stock solution,

the concentration system further includes a purification device that removes at least one of a hard component and a suspended matter 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 any one of a hard component and a suspended solids component from the concentrated liquid.

(3) The concentration system according to (1) or (2), wherein the purification apparatus removes a suspended matter component and a hard component in this order from at least any one of the first subject liquid, the concentrated liquid, the second subject liquid, and the diluted liquid.

According to the present invention, in a concentration system in which a concentrated raw solution discharged from a Reverse Osmosis (RO) module is further concentrated by Brine Concentration (BC), when the pressure is reduced and the concentrated solution discharged from the first chamber 11 of the semipermeable membrane module 1 is allowed to flow to the second chamber 12 of the semipermeable membrane module 1, and at least a part of the raw solution discharged from the second chamber 12 of the semipermeable membrane module 1 is reused as a target solution, it is possible to suppress membrane clogging and the like of the semipermeable membrane module and the RO module used for BC.

The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the present invention, which is to be read in connection with the accompanying drawings.

Drawings

Fig. 1 is a schematic diagram showing a concentration system according to an embodiment.

Fig. 2 is a schematic diagram showing a conventional concentration system.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals denote the same or corresponding parts. In addition, for the sake of clarity and simplification of the drawings, the dimensional relationships such as the length, width, thickness, and depth are changed as appropriate, and do not show the actual dimensional relationships.

< embodiment 1 >

Referring to fig. 1, the concentration system of the present embodiment mainly includes: a reverse osmosis component 2, a semi-permeable membrane component 1 and a purifying device 3.

In the reverse osmosis module 2, water is separated and recovered from the stock solution whose pressure has been raised to a predetermined pressure through the reverse osmosis membrane 20, and a first target solution (concentrated stock solution) which is the concentrated stock solution is discharged.

In the semipermeable membrane module 1, the semipermeable membrane 10 and the first chamber 11 and the second chamber 12 partitioned by the semipermeable membrane are provided, and the first object liquid is caused to flow into the first chamber 11 at a predetermined pressure, and the second object liquid is caused to flow into the second chamber 12 at a pressure lower than the predetermined pressure (the pressure of the first object liquid), whereby the water contained in the first object liquid in the first chamber 11 is transferred into the second object liquid in the second chamber 12 through the semipermeable membrane, 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 flows to the second chamber 12 as the second object liquid, and the diluted liquid discharged from the second chamber 12 is reused as at least a part of the stock liquid.

In the purification apparatus 3, at least one of a hard component and a suspended matter 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 apparatus 3, the "removal" of at least one of the hard component and the suspended solid component does not necessarily require the complete removal of at least one of the hard component and the suspended solid component, and at least a part of at least one of the hard component and the suspended solid component may be removed. That is, the amount of at least one of the hard component and the suspended solids component may be reduced.

The following describes the concentration system of the present embodiment in detail.

[ reverse osmosis Module ]

In the concentration system of the present embodiment, a high-pressure pump 2a is provided upstream of a Reverse Osmosis (RO) module 2. The high-pressure pump 2a increases the pressure of the raw liquid to a predetermined pressure and supplies the raw liquid to the first chamber 21 of the RO module 2. The RO module 2 separates water (permeate) from the raw liquid pressurized to a predetermined pressure through a Reverse Osmosis (RO) membrane 20 toward the second chamber 22, thereby discharging a concentrated raw liquid as a concentrated raw liquid from the first chamber 21 and discharging the water 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 to be supplied to the RO module 2, and any one of a solution and a suspension may be used. Examples of the stock solution include seawater, river water, brackish water, and drainage water. Examples of the drainage include industrial drainage, domestic drainage, drainage of oil fields and gas fields, and the like.

A pretreatment device (not shown) may be provided upstream of the high-pressure pump 2a to remove suspended solids (fine particles, microorganisms, scale components, and the like) contained in the raw liquid. Examples of the pretreatment apparatus include: a filtration apparatus using a sand filtration apparatus, an UF (Ultrafiltration) membrane, an MF (Microfiltration) membrane, or the like; chlorine, sodium hypochlorite, coagulant, scale inhibitor and the like; a pH value adjusting device and the like. The scale inhibitor is an additive having an action of preventing or suppressing precipitation of scale components in the liquid as scale. Examples of the scale inhibitor include 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). The concentrated raw liquid discharged from the first chamber 21 of the RO module 2 has a high pressure and is sent to the semipermeable membrane module 1 side by the pressure. That is, the concentrated raw liquid 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 Assembly ]

A 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 raw liquid) 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 fluid in the first chamber 11 passes through the semipermeable membrane 10 and passes into the second target fluid in the second chamber 12, and the concentrated fluid (the concentrated first target fluid) is discharged from the first chamber 11 and the diluted fluid (the diluted second target fluid) 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 flows 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 passes through the purification apparatus 3 described later and flows into the second chamber as the second target liquid, but the position of the purification apparatus 3 is not limited to this position.

In the case of fig. 1, since the subject fluid flowing into the first chamber 11 and the second chamber 12 of the semipermeable membrane module 1 is the same fluid, it has substantially equal osmotic pressures. Therefore, membrane separation of the target liquid (i.e., dilution of a part of the target liquid and concentration of another part of the target liquid) can be performed at a relatively low pressure without requiring a high pressure for reverse osmosis against a high osmotic pressure difference between the target liquid (i.e., high osmotic pressure liquid) and fresh water as in the RO method.

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

In this case, even if the concentration of the first target liquid flowing into the first chamber 11 is different from that of the second target liquid flowing into the second chamber 12, if the difference in osmotic pressure (absolute value) is smaller than the pressure of the first target liquid supplied into the first chamber 11, the membrane separation by BC can be theoretically performed. 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 preferably 30% or less of the predetermined pressure of the first target liquid supplied to the first chamber 11.

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 raw solution. Thus, the liquid discharged from the concentration system to the outside is only the concentrated liquid discharged from the first chamber 11 of the semi-permeable membrane module 1, which has reached the most concentrated state, and the water discharged from the second chamber 22 of the RO module 2. In this case, the concentrated solution is further treated, not directly discharged to the external environment such as the sea, the river, etc., and only water is discharged to the external environment, so that the liquid in a state concentrated via the raw solution is not discharged to the external environment like the diluted solution discharged from the second chamber 12 of the semipermeable membrane module 1, and adverse effects on the environment can be prevented.

The BC step may be a single-stage step using 1 semi-permeable membrane module 1 as shown in fig. 1, or may be a multistage step using a plurality of semi-permeable membrane modules.

In Brine Concentration (BC) as a membrane separation process in the semipermeable membrane module 1, in order to transfer water from the first chamber 11 to the second chamber 12 through 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 greater 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 a single-stage process (1 semi-permeable membrane module), it is necessary to supply the first target liquid under a high pressure corresponding to the high concentration, which has a disadvantage that energy consumption for operation of the pump increases. Therefore, the BC can be performed by a multistage process using a plurality of semipermeable membrane modules for the purpose of reducing the pressure required for the BC by staging the concentration process. BC performed by such a multistage process is disclosed in, for example, japanese patent application laid-open No. 2018-069198.

Examples of the semipermeable membrane include those called Reverse Osmosis (RO) membrane, Forward Osmosis (FO) membrane, and 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.

The pore diameters of the RO membrane and FO membrane are generally about 2nm or less, and the pore diameters of the UF membrane are about 2 to 100 nm. The NF membrane has a low rejection rate of ions and salts in the RO membrane, and generally, the pore diameter of the NF membrane is about 1 to 2 nm. When an RO membrane, an FO membrane or an NF membrane is used as the semipermeable membrane, the salt rejection 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 cellulose-based resins, polysulfone-based resins, and polyamide-based resins. The semipermeable membrane is preferably made of a material containing at least one of a cellulose resin and a polysulfone resin.

The cellulose resin is preferably an acetate resin. The cellulose acetate resin is resistant to chlorine as a bactericide and has a characteristic of inhibiting the growth of microorganisms. The cellulose acetate resin is preferably cellulose acetate, and more preferably cellulose triacetate in view of durability.

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

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

The form of the semipermeable membrane module 1 (and the reverse osmosis module 2) is not particularly limited, but when a hollow fiber membrane is used, examples thereof include a module in which a hollow fiber membrane is linearly arranged, a close-wound module in which a hollow fiber membrane is wound around a core tube, and the like. When a flat film is used, a laminate type module in which a flat film is laminated, a spiral type module in which a flat film is wound around a core tube in an envelope shape, and the like can be cited.

As an example of a specific hollow fiber membrane, a membrane having a single-layer structure entirely composed of a cellulose-based resin is cited. However, the single-layer structure described here does not require a membrane in which the entire layer is uniform, and it is preferable that a dense layer, which is a separation active layer substantially defining the pore diameter of the hollow fiber membrane, be provided in the vicinity of the outer peripheral surface, as disclosed in, for example, japanese patent laid-open No. 2012-115835.

As another example of a specific hollow fiber membrane, a membrane having a two-layer structure in which a dense layer made of a polyphenylene-based resin (e.g., sulfonated polyether sulfone) is provided on the outer peripheral surface of a support layer (e.g., a layer made of polyphenylene ether) can be cited. In addition, as another example, there is also a membrane having a two-layer structure in which a dense layer made of a polyamide resin is provided on the outer peripheral surface of a support layer (for example, a layer made of polysulfone or polyethersulfone).

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

[ purifying device ]

Thus, in the concentration system in which the concentrate raw solution discharged from the RO module is further concentrated by the BC, when the concentrate discharged from the first chamber 11 of the semipermeable membrane module 1 is caused to flow to the second chamber 12 of the semipermeable membrane module 1 by reducing the pressure and the diluent discharged from the second chamber 12 of the semipermeable membrane module 1 is reused as at least a part of the raw solution of the target solution, membrane clogging and the like of the semipermeable membrane module and the RO module used for the BC can be suppressed.

The removal of the hard component is performed, for example, by a softening and hydrating device described later.

The removal of the suspended matter component is performed, for example, by a suspended matter removal apparatus described later.

That is, the purification apparatus 3 includes, for example, the softening device, the suspended matter removing device, and the like.

In the purification apparatus 3, either the hard component or the suspended matter component may be removed, or both the hard component and the suspended matter component may be removed.

That is, the purification apparatus 3 may include only the demineralization apparatus, only the suspended matter removal apparatus, or both the demineralization apparatus and the suspended matter removal apparatus.

When both the hard component and the suspended substance component are removed from the concentrated raw liquid by the purification apparatus 3, it is preferable that the suspended substance component and the hard component are sequentially removed from the concentrated raw liquid and discharged as the first target liquid. That is, when the purification apparatus 3 includes both the demineralization apparatus and the suspension removal apparatus, it is preferable that the suspension removal apparatus and the demineralization apparatus are provided in this order from the upstream side of the flow of the concentrated raw liquid.

This is because, in removing the hard component, for example, a membrane having a finer porosity such as a nanofiltration membrane is used, and since membrane clogging tends to occur, a method of removing the suspended matter component first has a problem that membrane clogging or the like at the time of removing the hard component is difficult to occur.

As shown in fig. 1, the purification device 3 preferably removes at least one of a hard component and a suspended substance component from the concentrated solution discharged from the first chamber 11 of the semipermeable membrane module 1. That is, the purification apparatus 3 is preferably 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 amount of the purification apparatus can be reduced compared to a method of performing a purification treatment (removing at least one of the hard component and the suspended matter component) on the other first target liquid (concentrate) or the diluent, or the like, with respect to the concentrate discharged from the semipermeable membrane module 1. Therefore, the space required by the equipment is small, and the method has the advantage that the initial investment cost is low.

Since the pressure resistance of the purification apparatus 3 is not high in many cases, the concentrated solution having a high pressure discharged from the first chamber 11 of the semipermeable membrane module 1 is supplied to the purification apparatus 3 in a state where the pressure is reduced by the pressure reduction apparatus 4, for example. Therefore, a pump 1a for feeding the first target liquid to the second chamber 12 of the semipermeable membrane module 1 may be provided in the flow path from the purification apparatus 3 to the second chamber 12 of the semipermeable membrane module 1.

The pressure reducing device 4 may be, for example, a flow divider, a pressure reducer, or an energy recovery device.

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 solution is used.

As a mechanical energy recovery device, a power transmission type energy recovery device is known which recovers pressure energy of a concentrated solution as power by using a water turbine coupled coaxially with a drive shaft of a turbocharger or a high-pressure pump. 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 inverter (PX), may be used. Such an energy recovery device is disclosed in, for example, japanese patent application laid-open nos. 2004-81913 and 1-123605.

(Water softening apparatus)

The demineralizer is an apparatus for removing hard components (polyvalent ions such as calcium ions and magnesium ions) from a concentrated raw solution discharged from the RO module 1 to obtain a liquid having a reduced amount of hard components.

Examples of the demineralization apparatus include a membrane filtration apparatus using NF (Nanofiltration) and a treatment apparatus using an ion exchange resin. Such a demineralizer is disclosed in, for example, "demineralization using a modified RO MEMBRANE", MEMBRANEs (MEMBRANE), 38(6), 304 (TM), 309 (TM), 2013 (TM), and the like.

In addition, during the period when the operation of the concentration system is stopped, etc., it is preferable to perform maintenance of the demineralization apparatus. As the maintenance, for example, there are: in the case of a filtration apparatus using an NF membrane, chemical cleaning is performed, and in the case of a treatment apparatus using an ion exchange resin, a regeneration treatment of the ion exchange resin is performed.

(suspended substance removing device)

The suspended matter removing device is a device for removing suspended matter components (organic matter, insoluble matter such as microorganisms) from a concentrated raw solution discharged from the RO module 1 to obtain a liquid in which the amount of suspended matter components is reduced.

Examples of the suspended matter removing device include a filter device using a UF (Ultrafiltration) membrane.

In addition, during a period of time when the concentration system is stopped, maintenance of the suspended matter removing device is preferably performed. For maintenance, for example, if the filtration apparatus uses a UF membrane, back pressure cleaning, chemical cleaning, and the like can be further performed.

While the embodiments of the present invention have been described, it should be understood that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is defined by the scope of the claims, and is intended to include any modifications within the scope and meaning equivalent to the scope of the claims.

Claims

1. A concentration system is characterized by comprising:

a semipermeable membrane module having a semipermeable membrane and a first chamber and a second chamber partitioned by the semipermeable membrane, wherein the first target fluid is flowed into the first chamber at a predetermined pressure, the second target fluid is flowed into the second chamber at a pressure lower than the predetermined pressure, and water contained in the first target fluid in the first chamber is transferred into the second target fluid in the second chamber through the semipermeable membrane, a concentrated fluid is discharged from the first chamber, and a diluted fluid is discharged from the second chamber,

the diluent is reused as at least a portion of the stock solution,

2. The concentration system of claim 1, wherein the purification device removes at least any one of a hard component and a suspended solids component from the concentrate.

3. The concentration system according to claim 1 or 2, wherein the purification device removes a suspended matter component and a hard component in order from at least any one of the first subject liquid, the concentrated liquid, the second subject liquid, and the diluted liquid.