U.S. patent application number 17/269645 was filed with the patent office on 2021-11-04 for feedstock solution flow concentration system.
This patent application is currently assigned to Asahi Kasei Kabushiki Kaisha. The applicant listed for this patent is Asahi Kasei Kabushiki Kaisha. Invention is credited to Mitsuru Fujita, Daisuke Hotta, Masato Mikawa.
Application Number | 20210339194 17/269645 |
Document ID | / |
Family ID | 1000005724604 |
Filed Date | 2021-11-04 |
United States Patent
Application |
20210339194 |
Kind Code |
A1 |
Hotta; Daisuke ; et
al. |
November 4, 2021 |
Feedstock Solution Flow Concentration System
Abstract
A feedstock solution flow concentration system, which has a
first step for counterflowing or parallel flowing a feedstock
solution flow a containing a solute and a solvent b, and a draw
solution flow d via a forward osmosis membrane o and transferring
the solvent b in the feedstock solution flow a to the draw solution
flow d to obtain a concentrated feedstock solution flow c, which is
the feedstock solution flow which has been concentrated, and a
diluted draw solution flow e, which is the draw solution flow which
has been diluted.
Inventors: |
Hotta; Daisuke; (Tokyo,
JP) ; Fujita; Mitsuru; (Tokyo, JP) ; Mikawa;
Masato; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Asahi Kasei Kabushiki Kaisha |
Tokyo |
|
JP |
|
|
Assignee: |
Asahi Kasei Kabushiki
Kaisha
Tokyo
JP
|
Family ID: |
1000005724604 |
Appl. No.: |
17/269645 |
Filed: |
September 3, 2019 |
PCT Filed: |
September 3, 2019 |
PCT NO: |
PCT/JP2019/034656 |
371 Date: |
February 19, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 61/364 20130101;
B01D 2317/025 20130101; B01D 63/02 20130101; B01D 71/56 20130101;
C12H 1/063 20130101; B01D 61/366 20130101; B01D 61/005 20130101;
B01D 2313/50 20130101; C12G 1/00 20130101; B01D 61/58 20130101 |
International
Class: |
B01D 61/00 20060101
B01D061/00; B01D 61/36 20060101 B01D061/36; B01D 61/58 20060101
B01D061/58; B01D 63/02 20060101 B01D063/02; B01D 71/56 20060101
B01D071/56; C12H 1/07 20060101 C12H001/07; C12G 1/00 20060101
C12G001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 3, 2018 |
JP |
2018-164444 |
Claims
1. A feedstock solution flow concentration system, which has a
first step for counterflowing or parallel flowing a feedstock
solution flow containing at least a solute and a solvent and a draw
solution flow via a forward osmosis membrane and transferring the
solvent in the feedstock solution flow to the draw solution flow to
obtain a concentrated feedstock solution flow, which is the
feedstock solution flow which has been concentrated, and a diluted
draw solution flow, which is the draw solution flow which has been
diluted, wherein the draw solution flow contains a draw substance,
a common solute, and a solvent, the solvents of the feedstock
solution flow and the draw solution flow both contain water, the
common solute is a solute which is common between the feedstock
solution flow and the draw solution flow and is the same solute as
at least one type of solute among the solutes contained in the
feedstock solution flow, and the concentration of the common solute
in the draw solution flow is 1% to less than 100% of the
concentration of the common solute in the feedstock solution
flow.
2. The system according to claim 1, wherein the number average
molecular weight of the common solute is 15,000 or less.
3. The system according to claim 1, wherein the common solute is
one or more selected from an ester, a terpene, a phenylpropanoid, a
nucleic acid, a protein, a protein preparation, a vaccine, a sugar,
a peptide, an amino acid, a natural product pharmaceutical, a small
molecule pharmaceutical, an antibiotic, an antibiotic, a vitamin,
an inorganic salt, a protonic polar organic compound, and an
aprotic polar organic compound.
4. The system according to claim 3, wherein the common solute
comprises: a cation having at least one element selected from the
group consisting of sodium, magnesium, phosphorus, potassium,
calcium, chromium, manganese, iron, cobalt, copper, zinc, selenium,
and molybdenum, and an anion having at least one element selected
from the group consisting of oxygen, sulfur, nitrogen, chlorine,
and iodine.
5. The system according to claim 1, wherein the concentration of
the common solute in the draw solution flow is 6% to 96% of the
concentration of the common solute in the feedstock solution
flow.
6. The system according to claim 1, wherein the concentration of
the common solute in the draw solution flow is 30% to 96% of the
concentration of the common solute in the feedstock solution
flow.
7. The system according to claim 1, further comprising a second
step in which a solvent is separated from the draw solution flow to
obtain a concentrated draw solution flow, which is the draw
solution flow which has been concentrated.
8. The system according to claim 7, further comprising means for
using, in the first step, a draw solution flow prepared by mixing
the diluted draw solution flow obtained in the first step and the
concentrated draw solution flow obtained in the second step.
9. The system according to claim 7, wherein the second flow is
carried out using a membrane distillation process using a
semipermeable membrane.
10. The system according to claim 1, wherein the forward osmosis
membrane is used in the form of a forward osmosis membrane module
constituted by fiber bundle of a plurality of hollow fibers.
11. The system according to claim 10, wherein the forward osmosis
membrane is composite hollow fiber having an active separation
layer composed of a thin polymer membrane on an inner surface of a
hollow fiber-like porous support membrane.
12. The system according to claim 1, wherein the feedstock solution
flow is a food, pharmaceutical, pharmaceutical ingredient,
pharmaceutical raw material, or pharmaceutical intermediate.
13. The system according to claim 11, wherein the porous support
membrane consists of polyethersulfone or polysulfone, or both of
them, and the active separation layer is composed of a thin polymer
membrane of polyamide.
14. The system according to claim 3, wherein the concentration of
the common solute in the draw solution flow is 6% to 96% of the
concentration of the common solute in the feedstock solution
flow.
15. The system according to claim 3, wherein the concentration of
the common solute in the draw solution flow is 30% to 96% of the
concentration of the common solute in the feedstock solution
flow.
16. The system according to claim 3, wherein the forward osmosis
membrane is used in the form of a forward osmosis membrane module
constituted by a fiber bundle of a plurality of hollow fibers.
17. The system according to claim 16, wherein the forward osmosis
membrane is a composite hollow fiber having an active separation
layer composed of a thin polymer membrane on an inner surface of a
hollow fiber-like porous support membrane.
18. The system according to claim 17, wherein the porous support
membrane consists of polyethersulfone or polysulfone, or both of
them, and the active separation layer is composed of a thin polymer
membrane of polyamide.
19. The system according to claim 3, wherein the concentration of
the common solute in the draw solution flow is 6% to 96% of the
concentration of the common solute in the feedstock solution flow,
the forward osmosis membrane is used in the form of a forward
osmosis membrane module constituted by a fiber bundle of a
plurality of hollow fibers, the forward osmosis membrane is a
composite hollow fiber having an active separation layer composed
of a thin polymer membrane on an inner surface of a hollow
fiber-like porous support membrane, the porous support membrane
consists of polyethersulfone or polysulfone, or both of them, and
the active separation layer is composed of a thin polymer membrane
of polyamide.
Description
FIELD
[0001] The present invention relates to a feedstock solution flow
concentration system.
BACKGROUND
[0002] In various fields, it is sometimes necessary to concentrate
a feedstock solution.
[0003] As traditional concentration methods, for example,
evaporation methods and reverse osmosis methods are known.
[0004] Since evaporation methods require heating of the feedstock
solution, there are concerns about problems such as quality changes
due to heating and shape collapse of solid components.
[0005] Since reverse osmosis requires pressurization, when used in
a high concentration feedstock solution, membrane clogging is
likely to occur, and there is a limit in that the concentration
efficiency is limited by the capacity of the pressurizing pump.
[0006] As a feedstock solution concentration method, the forward
osmosis method is also known. The forward osmosis method is a
method of transferring a solvent from a feedstock solution flow to
a draw solution by adjoining a feedstock solution flow and a draw
solution flow via a forward osmosis membrane. Since the forward
osmosis method does not require pressurization, it is expected that
highly efficient concentration can be continued for long periods of
time even when applied to a high-concentration feedstock
solution.
[0007] However, there is a concern that some of the solute
components in the feedstock solution flow may leak into the draw
solution flow, whereby the component composition of the obtained
concentrated solution may change.
[0008] In connection thereto, Patent Literature 1 proposes a
technology in which the feedstock solution flow itself after
concentration is used as the draw solution flow.
[0009] Patent Literature 2 proposes a technology in which
membrane-permeable solute components are prevented from leaking
from a feedstock solution to a draw solution flow by including the
membrane-permeable solute components in the feedstock solution in
the draw solution flow at concentrations higher than the
concentrations thereof in the feedstock solution.
CITATION LIST
Patent Literature
[0010] [PTL 1] Japanese Unexamined Patent Publication (Kokai) No.
2016-150308
[0011] [PTL 2] WO 2016/21337
SUMMARY
Technical Problem
[0012] Patent Literature 1 describes that, according to the
technology described therein, even if a solute component is mixed
from the draw solution flow to the feedstock solution flow, it is
possible to prevent adverse effects on the component composition of
the obtained concentrate solution.
[0013] However, according to this method, in addition to requiring
a step of preparing a concentrate of the feedstock solution flow as
draw solution flow, there is a concern that the presence of
feedstock solution flows on both sides of the forward osmosis
membrane may cause clogging of the membrane, whereby the desired
concentrate magnification cannot be obtained.
[0014] In order to carry out the method described in Patent
Literature 1, a step of preparing a concentrate of the feedstock
solution flow is required. Thus, there is a concern that loss or
alteration of components in the feedstock solution may occur. When
a concentrate solution in which loss or alteration of the
components thereof has occurred is used as the draw solution flow,
the component balance of the obtained concentrate may be disturbed,
or the altered components may leak and diffuse into the feedstock
solution flow, whereby the quality of the product may be
impaired.
[0015] According to the method of Patent Literature 2, the
membrane-permeable solute should be included in the draw solution
flow at a high concentration. Thus, it is necessary to prepare a
large amount of the membrane-permeable solute. When carrying out
the method of Patent Literature 2, the membrane-permeable solute
contained at a high concentration in the draw solution flow may
leak and diffuse in the feedstock solution flow, and there is a
concern that the component balance of the obtained concentrate may
be lost.
[0016] The present invention has been conceived in light of such
circumstances.
[0017] The object of the present invention is to provide a
concentration system using a forward osmosis membrane with which
the feedstock solution flow can be concentrated with high
efficiency by a simple method, and in which the diffusion of solute
components in the feedstock solution flow into draw solution flow
is controlled.
Solution to Problem
[0018] In other words, the present invention is as described
below.
<<Aspect 1>>
[0019] A feedstock solution flow concentration system, which has a
first step for counterflowing or parallel flowing a feedstock
solution flow containing at least a solute and a solvent and a draw
solution flow via a forward osmosis membrane and transferring the
solvent in the feedstock solution flow to the draw solution flow to
obtain a concentrated feedstock solution flow, which is the
feedstock solution flow which has been concentrated, and a diluted
draw solution flow, which is the draw solution flow which has been
diluted, wherein [0020] the draw solution flow contains a draw
substance, a common solute, and a solvent, [0021] the solvents of
the feedstock solution flow and the draw solution flow both contain
water, [0022] the common solute is a solute which is common between
the feedstock solution flow and the draw solution flow and is the
same solute as at least one solute among the solutes contained in
the feedstock solution flow, and [0023] the concentration of the
common solute in the draw solution flow is 1% to less than 100% of
the concentration of the common solute in the feedstock solution
flow.
<<Aspect 2>>
[0024] The system according to aspect 1, wherein the number average
molecular weight of the common solute is 15,000 or less.
<<Aspect 3>>
[0025] The system according to aspect 1 or 2, wherein the common
solute is one or more selected from an ester, a terpene, a
phenylpropanoid, a nucleic acid, a protein, a protein preparation,
a vaccine, a sugar, a peptide, an amino acid, a natural product
pharmaceutical, a small molecule pharmaceutical, an antibiotic, an
antibiotic, a vitamin, an inorganic salt, a protonic polar organic
compound, and an aprotic polar organic compound.
<<Aspect 4>>
[0026] The system according to aspect 3, wherein the common solute
comprises: [0027] a cation having at least one element selected
from the group consisting of sodium, magnesium, phosphorus,
potassium, calcium, chromium, manganese, iron, cobalt, copper,
zinc, selenium, and molybdenum, and [0028] an anion having at least
one element selected from the group consisting of oxygen, sulfur,
nitrogen, chlorine, and iodine.
<<Aspect 5>>
[0029] The system according to any one of aspects 1 to 4, wherein
the concentration of the common solute in the draw solution flow is
6% to 96% of the concentration of the common solute in the
feedstock solution flow.
<<Aspect 6>>
[0030] The system according to any one of aspects 1 to 4, wherein
the concentration of the common solute in the draw solution flow is
30% to 96% of the concentration of the common solute in the
feedstock solution flow.
<<Aspect 7>>
[0031] The system according to any one of aspects 1 to 6, further
comprising a second step in which a solvent is separated from the
draw solution flow to obtain a concentrated draw solution flow,
which is the draw solution flow which has been concentrated.
<<Aspect 8>>
[0032] The system according to aspect 7, further comprising means
for using, in the first step, a draw solution flow prepared by
mixing the diluted draw solution flow obtained in the first step
and the concentrated draw solution flow obtained in the second
step.
<<Aspect 9>>
[0033] The system according to aspect 7 or 8, wherein the second
flow is carried out using a membrane distillation process using a
semipermeable membrane.
<<Aspect 10>>
[0034] The system according to any one of aspects 1 to 9, wherein
the forward osmosis membrane is used in the form of a forward
osmosis membrane module constituted by fiber bundle of a plurality
of hollow fibers.
<<Aspect 11>>
[0035] The system according to aspect 10, wherein the forward
osmosis membrane is composite hollow fibers each having an active
separation layer composed of a thin polymer membrane on an inner
surface of a hollow fiber-like porous support membrane.
<<Aspect 12>>
[0036] The system according to any one of aspects 1 to 11, wherein
the feedstock solution flow is a food, pharmaceutical,
pharmaceutical ingredient, pharmaceutical raw material, or
pharmaceutical intermediate.
Advantageous Effects of Invention
[0037] According to the present invention, there is provided a
system using a forward osmosis membrane with which the feedstock
solution flow can be concentrated with high efficiency by a simple
method, and in which the diffusion of solute components in the
feedstock solution flow into draw solution flow is controlled. The
present invention can be suitably applied to applications such as
concentration of foods and pharmaceuticals; treatment of precursor
solutions for chemical synthesis; and treatment of produced water
discharged from shale gas and oil fields.
BRIEF DESCRIPTION OF DRAWINGS
[0038] FIG. 1 is a conceptual diagram detailing an example of the
system of the present invention.
[0039] FIG. 2 is a conceptual diagram detailing another example of
the system of the present invention.
DESCRIPTION OF EMBODIMENTS
<<Feedstock Solution Flow Concentration System>>
[0040] The feedstock solution flow concentration system of the
present invention is: [0041] a feedstock solution flow
concentration system, which has a step (first step) for
counterflowing or parallel flowing a feedstock solution flow
containing at least a solute and a solvent and a draw solution flow
via a forward osmosis membrane and transferring the solvent in the
feedstock solution flow to the draw solution flow to concentrate
the feedstock solution flow, wherein [0042] the draw solution flow
contains a draw substance, a common solute, and a solvent, [0043]
the solvents of the feedstock solution flow and the draw solution
flow both contain water, [0044] the common solute is a solute which
is common between the feedstock solution flow and the draw solution
flow and is the same solute as at least one solute among the
solutes contained in the feedstock solution flow, and [0045] the
concentration of the common solute in the draw solution flow is 1%
to less than 100% of the concentration of the common solute in the
feedstock solution flow.
[0046] The feedstock solution flow concentration system of the
present invention may further have a step (second step) in which
the solvent is removed from the draw solution flow to obtain a
concentrated draw solution flow, which is the draw solution flow
which has been concentrated.
[0047] First, a summary of the feedstock solution flow
concentration system of the present invention will be described
with referring to FIGS. 1 and 2.
[0048] FIG. 1 is a conceptual diagram detailing the feedstock
solution flow concentration system of the present invention having
a first step.
[0049] In the first step, a feedstock solution flow and a draw
solution flow are counterflowed or parallel flowed via a forward
osmosis membrane and the solvent in the feedstock solution flow is
transferred to the draw solution flow, whereby the feedstock
solution flow is concentrated.
[0050] In the first step of the feedstock solution flow
concentration system of FIG. 1, a forward osmosis membrane o is
provided, and a unit A which carries out a forward osmosis process
is used. The interior space of the unit A is bifurcated by the
forward osmosis membrane o into a feedstock solution flow-side
space R and a draw solution flow-side space D. A feedstock solution
flow a, which is the concentration target, is introduced into the
feedstock solution flow-side space R of the unit A. A draw solution
flow d is introduced into the draw solution flow-side space D of
the unit A.
[0051] The feedstock solution flow a contains a solute Xn and a
solvent b. The draw solution flow d contains a draw substance Xm,
the solute (common solute) Xn, and the solvent b. The solute Xn in
the feedstock solution flow a and the solute Xn in the draw
solution flow d are the same type of solute, and are a common
solute which is common between both flows. When the feedstock
solution flow a contains a plurality of types of solutes, the
common solute may be a part of the plurality of types of solutes or
may be the entirety thereof.
[0052] When the feedstock solution flow a and the draw solution
flow d are counterflowed or parallel flowed via the forward osmosis
membrane o, using the osmotic pressure difference between the two
solutions as a driving force, the solvent b in the feedstock
solution flow a passes through the forward osmosis membrane o and
is transferred to the draw solution flow d side. As a result, a
concentrated feedstock solution flow c, which is the feedstock
solution flow which has been concentrated, and a diluted draw
solution flow e, which is the draw solution flow which has been
diluted, are obtained. Though the feedstock solution flow a and the
draw solution flow d are counterflowed in the first step of FIG. 1,
they may be parallel flowed.
[0053] The concentration of the common solute Xn in the draw
solution flow d is set so as to be less than the concentration of
the common solute Xn in the feedstock solution flow a. As a result,
the osmotic pressure difference which serves as a driving force for
transferring the solute Xn in the feedstock solution flow a to the
draw solution flow d side is mitigated. It is believed that since
the concentration of the common solute Xn of the draw solution flow
d is less than that of the feedstock solution flow a, the common
solute Xn is not transferred from the draw solution flow d to the
feedstock solution flow a. As a result, it is possible to
effectively concentrate the feedstock solution flow a without
changing the solute components.
[0054] FIG. 2 is a conceptual diagram detailing the feedstock
solution flow concentration system of the present invention having
the first step and a second step.
[0055] The first step of FIG. 2 is the same as the case of FIG.
1.
[0056] In the second step of FIG. 2, the solvent b is removed from
the draw solution flow d to obtain a concentrated draw solution
flow f, which is the draw solution flow which has been
concentrated.
[0057] In the second step of the feedstock solution flow
concentration system of FIG. 2, a unit B which has a semipermeable
membrane p and which carries out a membrane distillation process is
used. The interior space of the unit B is bifurcated by the
semipermeable membrane p into a liquid phase L and a gas phase G.
The draw solution flow d, which is the concentration target, is
introduced into the liquid phase L of the unit B. The pressure of
the gas phase G of the unit B is set to a vacuum.
[0058] The draw solution flow d contains the draw substance Xm, the
common solute Xn, and the solvent b.
[0059] The solvent b in the draw solution flow d introduced into
the unit B is transferred though the semipermeable membrane p into
the vacuum-side cavity. As a result, the concentrated draw solution
flow f and the solvent b are obtained.
[0060] In place of the membrane distillation process, a
distillation process or forward osmosis process may be used in the
second step.
[0061] In the feedstock solution flow concentration system of FIG.
2, the first step and the second step are connected via a buffer
tank.
[0062] The buffer tank shown in FIG. 2 has a function of mixing the
optimum mixing amounts of the diluted draw solution flow e obtained
in the first step and the concentrated draw solution flow f
obtained in the second step to prepare the draw solution flow d. As
a result, in the feedstock solution flow concentration system of
FIG. 2, the draw solution flow d can be continuously supplied to
the unit A of the first step and the unit B of the second step, and
thus, concentration of the feedstock solution flow using a forward
osmosis membrane can be continuously carried out for long periods
of time.
[0063] Reference signs r1 and r2 in FIG. 2 are feed pumps, q1 is a
heat exchanger, and q2 is a cooling device.
[0064] In the feedstock solution flow concentration system of FIG.
2, the first step and the second step are connected via the buffer
tank. However, in the present invention, this buffer tank is not an
indispensable requirement. For example, the diluted draw solution
flow e obtained in the first step may be directly fed to the unit B
of the second step, and the concentrated draw solution flow f
obtained in the second step may be used as the draw solution flow d
of the first step.
[0065] In the second step, the unit B, which carries out a membrane
distillation process, is used. However, in the present invention,
in the second step, another means which can concentrate the draw
solution flow d to obtain the concentrated draw solution flow f may
be used. For example, an evaporation means other than a membrane
distillation process may be used as the concentration means.
[0066] In the second step, the evaporation means other than
membrane distillation may be, for example, a distillation process,
a vacuum distillation process, or a natural drying process.
However, carrying out the second step by a membrane distillation
process is preferable from the viewpoint that the size of the
feedstock solution flow concentration system of the present
invention can be reduced.
[0067] When an evaporation means is used in the second step, since
the feedstock solution flow concentration system adiabatically
compresses the generated vapor of the solvent b into
high-temperature compressed vapor, a mechanical vapor recompression
(MVR) means may further be provided. The heat of the
high-temperature compressed vapor obtained by MVR can be reused for
the evaporation means in the second step.
<<Elements of Feedstock Solution Flow Concentration
System>>
[0068] A summary of the feedstock solution flow concentration
method by the feedstock solution flow concentration system of the
present invention was described above. Next, the elements
constituting the feedstock solution flow concentration system of
the present invention will be described in detail below.
<Feedstock Solution Flow a>
[0069] The feedstock solution flow a is a fluid containing a solute
as the target of concentration and the solvent b. The feedstock
solution flow a may be an emulsion as long as it is a fluid.
[0070] Examples of the feedstock solution flow a used in the
present invention include foods, pharmaceutical raw materials,
seawater, and produced water discharged from gas and oil fields.
However, in the feedstock solution flow concentration system of the
present invention, the draw solution flow d contains the solute
common with the feedstock solution flow a in a range of 1% to less
than 100% of the concentration of the common solute in the
feedstock solution flow a. By including the common solute in the
draw solution flow d in this concentration range, the transfer of
the solute from the feedstock solution flow a to the draw solution
flow d can be controlled, and a concentrate in which the
composition ratio of the feedstock solution flow a is maintained or
substantially maintained is obtained.
[0071] According to or in accordance with the technology of Patent
Literature 2, if the concentration of the common solute in the draw
solution flow d is equal to or greater than the concentration of
the common solute in the feedstock solution flow a, the common
solute in the draw solution flow d leaks and diffuses into the
feedstock solution flow a, whereby disruption of the composition
ratio of the components in the obtained concentrate often
occurs.
[0072] In connection thereto, in the feedstock solution flow
concentration system of the present invention, the concentration of
the common solute in the draw solution flow d is adjusted to a
range lower than the concentration of the common solute in the
feedstock solution flow a, specifically, a range of 1% to less than
100%. Thus, leakage and diffusion of the common solute in the draw
solution flow d into the feedstock solution flow a can be
suppressed, and as a result, the component composition ratio of the
feedstock solution flow a can be concentrated as-is or
substantially as-is.
[0073] Thus, when the feedstock solution flow concentration system
of the present invention is used for foods, concentration can be
carried out with less loss of aroma components and color
components. When the system of the present invention is used for
concentration of pharmaceuticals or the raw materials thereof, the
component balance before and after concentration is substantially
maintained, whereby concentration can be carried out in a state in
which pharmaceutical efficacy is maintained.
[0074] For the reasons described above, in the feedstock solution
flow concentration system of the present invention, it is
preferable that a solution containing a low molecular weight solute
which can pass through the forward osmosis membrane (semipermeable
membrane) depending on the conditions be used as the feedstock
solution flow and at least one of the low molecular weight solutes
be the solute common between the feedstock solution flow and the
draw solution flow.
[0075] The low molecular weight solute may be a material having a
number average molecular weight of, for example, 15,000 or less.
The number average molecular weight of the low molecular weight
solute may be, for example, 30 or more, 50 or more, 100 or more,
500 or more, 1,000 or more, 3,000 or more, or 6,000 or more. It may
be difficult for the solute having a number average molecular
weight of 6,000 or more to pass through the forward osmosis
membrane, depending on the conditions, but by appropriately setting
the implementation conditions, it can pass through the forward
osmosis membrane, and even in such a case, the desired effect of
the present application is advantageously exhibited.
[0076] The feedstock solution flow a used in the present invention
is preferably a food, pharmaceutical, pharmaceutical ingredient,
pharmaceutical raw material, or pharmaceutical intermediate.
[0077] Examples of foods to be concentrated by the feedstock
solution flow concentration system of the present invention include
coffee extract, juice (for example, orange juice and tomato juice),
alcoholic beverages (for example, wine and beer), dairy products
(for example, lactic acid bacteria beverages and raw milk), soup
stock (for example, kelp stock and bonito stock), tea extract,
aromatic emulsions (for example, emulsions such as vanilla essence
and strawberry essence), syrups (for example, maple syrup and
honey), and food oil emulsions (for example, emulsions of rapeseed
oil, olive oil, sunflower oil, safflower, and corn).
(Solute of Feedstock Solution Flow a)
[0078] The food, pharmaceutical, pharmaceutical ingredient,
pharmaceutical raw material, or pharmaceutical intermediate to be
concentrated by the feedstock solution flow concentration system of
the present invention includes, as a solute, a useful substance
selected from the group consisting of nucleic acids, proteins,
sugars, peptides, amino acids, antibiotics, natural product
pharmaceuticals, small molecule pharmaceuticals, and vitamins. The
number average molecular weights of these solutes are preferably
100 or more, from the viewpoint of ensuring the medicinal
properties thereof, and are preferably 6,000 or less, from the
viewpoint of suppression adhesion to the forward osmosis
membrane.
[0079] Specific examples of the solutes contained in the food,
pharmaceutical, pharmaceutical ingredient, pharmaceutical raw
material, or pharmaceutical intermediate are described below.
[0080] Examples of nucleic acids include oligonucleotides, RNA,
siRNA, miRNA, aptamers, decoys, CpG oligos, antisenses, mipomersen,
eteplirsen, nusinersen, and pegaptanib.
[0081] Examples of proteins include protein preparations and
vaccines. Examples of protein preparations include interferon
.alpha., interferon .beta., interleukins 1 to 12, growth hormone,
erythropoietin, insulin, granulocyte colony stimulating factor
(G-CSF), tissue plasminogen activator (TPA), natriuretic peptides,
blood coagulation factor VIII, somatomedin, glucagon, growth
hormone-releasing factors, serum albumin, and calcitonin, and
examples of vaccines include hepatitis A vaccines, hepatitis B
vaccines, and hepatitis C vaccines.
[0082] Examples of sugars include monosaccharides (for example,
glucose, fructose, galactose, mannose, ribose, and deoxyribose),
disaccharides (for example, maltose, sucrose, and lactose), and
sugar chains (for example, in addition to glucose, galactose,
mannose, fucose, xylose, glucuronic acid, and iduronic acid, sugar
derivatives such as N-acetylglucosamine, N-acetylgalactosamine, and
N-acetylneuraminic acid).
[0083] The term "peptide" means a compound in which two or more
arbitrary amino acids are bonded, and the term encompasses
dipeptides in which two amino acids are bonded, tripeptides in
which three amino acids are bonded, oligopeptides in which 4 to 10
amino acids are bonded, and polypeptides in which 11 or more amino
acids are bonded. The peptides may be chained or cyclic.
[0084] Examples of amino acids include essential amino acids,
non-essential amino acids, and non-natural amino acids. Examples of
essential amino acids include tryptophan, lysine, methionine,
phenylalanine, threonine, valine, leucine, and isoleucine. Examples
of non-essential amino acids include arginine, glycine, alanine,
serine, tyrosine, cysteine, asparagine, glutamine, proline,
aspartic acid, and glutamic acid.
[0085] The phrase "non-natural amino acids" means amino acids which
are not present in nature, and examples thereof include "labeled
amino acids" in which an arbitrary labeling compound is combined
with an amino acid skeleton. The labeling compound may be, for
example, a dye, a fluorescent substance, a chemical luminescent
substance, a bioluminescent substance, an enzyme substrate, a
coenzyme, an antigenic substance, or a protein-binding substance.
Specific examples of non-natural amino acids include
photoresponsive amino acids, optical switch amino acids,
fluorescent probe amino acids, and fluorescent labeled amino
acids.
[0086] Examples of antibiotics include streptomycin and
vancomycin.
[0087] Examples of natural product pharmaceuticals include
cyclosporine, eribulin, rapamycin, and tacrolimus.
[0088] Examples of small molecule pharmaceuticals include
ledipasvir, revlimid, fluticasone, sofosbuvir, rosuvastatin,
pregabalin, imatinib, tiotropium, sitagliptin, emtricitabine,
altovastatin, clopidogrel, amlodipine, esomeprazole, simvastatin,
olanzapine, valsartan, venlafaxine, sertraline, ranitidine,
omeprazole, enalapril, nifedipine, fluoxetine, pravastatin,
famotidine, captopril, and acetaminophen. Substances similar
thereto, progenitors, and intermediates thereof may be used. The
molecular weights of the small molecular pharmaceuticals are
preferably 2,000 or less.
[0089] Examples of vitamins include vitamin A, B-group vitamins,
and vitamin C, and encompasses derivatives and salts thereof.
Examples of B-group vitamins include vitamin B6 and vitamin
B12.
(Common Solute)
[0090] At least one solute included in the feedstock solution flow
a is also contained in the draw solution flow d. This solute, as
used herein, is referred to below as the common solute Xn, which is
common between the feedstock solution flow a and the draw solution
flow d.
[0091] Among the solutes contained in the feedstock solution flow
a, examples of the common solute include esters, terpenes
(terpenoids), phenylpropanoids, nucleic acids, proteins, protein
preparations, vaccines, sugars, peptides, amino acids, natural
product pharmaceuticals, small molecule pharmaceuticals,
antibiotics, antibiotics, vitamins, inorganic salts, protonic polar
organic compounds, and aprotic polar organic compounds. By using
one or more of these as the common solute, a concentrated food
having an excellent flavor in which the composition of the aromatic
components is maintained, or a concentrated pharmaceutical in which
the composition of the medicinal ingredients is maintained and the
medicinal effect is maintained is obtained, which is
preferable.
[0092] As specific examples thereof: [0093] examples of esters
include ethyl butyrate, ethyl isobutyrate, methyl 2-methylbutyrate,
and ethyl methylbutanoate; [0094] examples of terpenes include
.alpha.-pinene, .beta.-pinene, sabinene, myrcene, cymene, ocimene,
terpinene, linalool, borneol, thymol, .alpha.-ionone,
.beta.-ionone, .gamma.-ionone, and .beta.-citronellol; and [0095]
examples of phenylpropanoids include cinnamic acid,
3,4-dihydroxycinnamic acid (also referred to as caffeic acid),
eugenol, anethole, sesamin, lignans, lignin, and cinnamyl
acetate.
[0096] The inorganic salts may be a salt comprising a cation having
at least one element selected from the group consisting of sodium,
magnesium, phosphorus, potassium, calcium, chromium, manganese,
iron, cobalt, copper, zinc, selenium, and molybdenum, and [0097] an
anion having at least one element selected from the group
consisting of oxygen, sulfur, nitrogen, chlorine, and iodine, and
is preferably selected from alkali metal halides, alkali metal
carbonates, alkali metal nitrates, alkali metal sulfates, alkali
metal sulfites, alkali metal thiosulfates, alkaline earth metal
halides, alkaline earth metal carbonates, alkaline earth metal
nitrates, alkaline earth metal sulfates, alkaline earth metal
sulfites, and alkaline earth metal thiosulfates, as well as various
ammonium salts.
[0098] Specific examples of inorganic salts include sodium
chloride, potassium chloride, magnesium chloride, calcium chloride,
sodium sulfate, magnesium sulfate, sodium thiosulfate, sodium
sulfite, ammonium chloride, ammonium sulfate, and ammonium
carbonate.
[0099] Specific examples of the nucleic acids, proteins, protein
preparations, vaccines, sugars, peptides, amino acids, natural
product pharmaceuticals, small molecule pharmaceuticals,
antibiotics, antibiotics, and vitamins preferably used as the
common solute include those exemplified above as solutes included
in the feedstock solution flow.
[0100] Examples of protonic polar organic compounds include
n-butanol, isopropanol, nitromethane, ethanol, methanol, and acetic
acid; and [0101] examples of aprotic polar organic compounds
include N-methylpyrrolidone, tetrahydrofuran, acetone,
dimethylformamide, acetonitrile, and dimethyl sulfoxide. These
protonic polar organic compounds and aprotic polar organic
compounds can be used as the common solute of the present invention
as long as the feedstock solution flow concentration system of the
present invention is not adversely affected thereby, such as
causing defects of the forward osmosis membrane.
(Solvent of Feedstock Solution Flow a)
[0102] The solvent b of the feedstock solution flow is a fluid
containing water and may be water or a mixed solvent of water and a
water-soluble organic solvent, and is preferably capable of
dissolving or dispersing the above solutes. The solvent b is
commonly water.
<Draw Solution Flow d>
[0103] The draw solution flow d contains the common solute Xn,
which is the same as at least one of the solutes contained in the
feedstock solution flow a, the draw substance Xm, and the solvent
b, and is a fluid which has a higher osmotic pressure than the
feedstock solution flow a and does not significantly denature the
forward osmosis membrane o. The common solute Xn is common with a
part or all of the solutes Xn contained in the feedstock solution
flow a. The concentration of the common solute Xn in the draw
solution flow d is set to 1% to less than 100% of the concentration
of the common solute Xn in the feedstock solution flow a. When the
common solute Xn includes a plurality of types of solutes, the
concentration is preferably set, for each type of common solutes
Xn, so that the concentration in the draw solution flow d is 1% to
less than 100% of the concentration in the feedstock solution flow
a.
[0104] When the feedstock solution flow a and the draw solution
flow d as described above come into contact via the forward osmosis
membrane o, which is a semipermeable membrane, the solvent b in the
feedstock solution flow a passes through the forward osmosis
membrane o and is transferred to the draw solution flow d, and at
this time, transfer of the common solute Xn in the feedstock
solution flow to the draw solution flow d side is suppressed.
[0105] In the present invention, by carrying out the forward
osmosis processing such a draw solution flow d, the feedstock
solution flow a can be concentrated while maintaining or
substantially maintaining the component composition of the
solute.
(Common Solute Xn)
[0106] As the common solute Xn in the draw solution flow d, one or
more may be suitable selected and used from among the solutes
contained in the feedstock solution flow in accordance with the
type and properties of the feedstock solution flow a, which is the
target of concentration, and the application of the concentrate.
Regarding this, refer to the foregoing.
[0107] The concentration of the common solute Xn in the draw
solution flow d is 1% to less than 100% of the concentration of the
common solute Xn in the feedstock solution flow a. From the
viewpoint that the elution suppression performance of the common
solute Xn becomes remarkable, the concentration of the common
solute Xn in the draw solution flow d is preferably 1% to 99% or 6%
to 96% with respect to the concentration (mass %) of the common
solute Xn in the feedstock solution flow a. The ratio is more
preferably 30% to 96%, and in this range, elution of the common
solute Xn from the feedstock solution flow a to the draw solution
flow d is suppressed to a practically negligible level.
[0108] If the concentration of the common solute Xn in the draw
solution flow d is 1% or more with respect to the concentration of
the common solute Xn in the feedstock solution flow a, leakage of
the common solute Xn from the draw solution flow d can be
suppressed. If the concentration of the common solute X is 6% or
more with respect to the concentration of the common solute Xn in
the feedstock solution flow a, the effect of suppressing elution of
the common solute Xn from the feedstock solution flow a to the draw
solution flow d is significantly higher, which is preferable. It is
preferable that this ratio be 96% or less, since clogging of the
forward osmosis membrane o and leakage of the common solute Xn from
the draw solution flow d are unlikely to occur, and the solubility
or dispersibility of the draw substance Xm in the draw solution d
is improved and a high osmotic pressure can be obtained.
[0109] When the draw solution flow d contains a plurality of types
of common solutes Xn, it is sufficient that one thereamong satisfy
the above concentration conditions. However, it is preferable that
all of the common solutes Xn contained in the draw solution flow d
be 1% to less than 100% of the concentration (mass %) of the
corresponding common solute Xn in the feedstock solution flow
a.
[0110] Even if the common solute Xn is present as ions ionized in
the solvent b, the concentration of the common solute Xn in the
present invention is determined based on the value of the formula
weight prior to ionization.
(Draw Substance Xm)
[0111] The draw substance Xm is a material which is contained in
the draw solution flow d, and imparts the draw solution flow d with
a higher osmotic pressure than the feedstock solution flow a.
[0112] Examples of the draw substance Xm which can be used in the
present invention include inorganic salts, sugars, alcohols, and
polymers.
[0113] Examples of inorganic salts include sodium chloride,
potassium chloride, magnesium chloride, calcium chloride, sodium
sulfate, magnesium sulfate, sodium thiosulfate, sodium sulfite,
ammonium chloride, ammonium sulfate, and ammonium carbonate; [0114]
examples of sugars include general sugars such as sucrose, fructose
and glucose, and special sugars such as oligosaccharides and rare
sugars; [0115] examples of alcohols include monoalcohols such as
methanol, ethanol, 1-propanol and 2-propanol, and glycols such as
ethylene glycol and propylene glycol; and [0116] examples of
polymers include polymers such as polyethylene oxide and propylene
oxide, as well as copolymers thereof.
[0117] The examples of the draw substance Xm above partially
overlap the examples of the common solutes Xn. The materials for
which the examples overlap can be used as the common solute Xn or
can be used as the draw substance Xm. However, a draw solution flow
d containing a certain material as the draw substance Xm cannot be
used to concentrate a feedstock solution flow a containing the
certain material as the common solute Xn. This is because, since
the concentration of the common solute Xn in the draw solution flow
d is limited to 1% to less than 100% of the concentration of the
common solute Xn in the feedstock solution flow a, it is unlikely
that the draw solution flow d will be imparted with a higher
osmotic pressure than the feedstock solution flow a at such low
concentrations.
[0118] The concentration of the draw substance Xm in the draw
solution flow d is set so that the osmotic pressure of the draw
solution flow d is higher than the osmotic pressure of the
feedstock solution flow a. As long as the osmotic pressure of the
draw solution flow d is higher than the osmotic pressure of the
feedstock solution flow a, it may fluctuate within that range.
[0119] To determine the osmotic pressure difference between two
liquids, one of the following methods can be used. [0120] (1) When
the two liquids separate into two phases after mixing: it is
determined that a liquid having an increased volume after the
separation into two phases has a higher osmotic pressure; or [0121]
(2) when the two liquids do not separate into two phases after
mixing: the two liquids are brought into contact with each other
via the forward osmosis membrane o, and it is determined that a
liquid having an increased volume after a certain period of time
has a higher osmotic pressure. At this time, the certain period of
time depends on the osmotic pressure difference, but is generally
in the range of several minutes to several hours.
[0122] The common solute Xn along with the draw substance Xm
contributes to the generation of the osmotic pressure of the draw
solution flow d. Thus, for setting of the concentration of the draw
substance Xm in the draw solution flow d, for example, the Van't
Hoff formula may be used after considering the concentration of the
common solute Xn in the draw solution flow d.
[0123] As a typical example, when water is used as the solvent b
and a water-soluble inorganic salt is used as the draw substance
Xm, the concentration of the draw substance Xm in the draw solution
flow d can be, for example, in the range of 15% by mass to 60% by
mass.
(Solvent of Draw Solution Flow d)
[0124] The solvent of the draw solution flow d is a fluid
containing water, is preferably capable of dissolving or dispersing
the common solute Xn and the draw substance Xm, and is preferably a
solvent of the same type as the solvent b to be separated from the
feedstock solution flow a. For example, if the solvent of the
feedstock solution flow a is water, the solvent of the draw
solution flow d is also preferably water.
(Draw Solution Flow d Preparation Method)
[0125] The draw solution flow d used in the present invention can
be prepared by dissolving or dispersing the common solute Xn and
the draw substance Xm in the solvent b.
[0126] As described above, in the feedstock solution flow
concentration system of the present invention, the concentration of
the common solute in the draw solution is 1% to less than 100% of
the concentration of the common solute in the feedstock solution
flow, and may be 1% to 99%, 6% to 96%, or 30% to 96%.
[0127] The common solute Xn may be introduced into the draw
solution flow d by the addition of the feedstock solution flow a
itself or may be introduced into the draw solution flow d by the
addition of components corresponding to the common solute Xn.
[0128] When the introduction of the common solute Xn into the draw
solution flow d is carried out by the addition of the feedstock
solution flow a itself, it is not necessary to prepare a large
amount of concentrate or common solute of the feedstock solution
flow in advance, whereby the draw solution flow d can be prepared
by a simple means.
[0129] The addition of the common solute Xn and the draw substance
Xm into the solvent b may be carried out at any time during which
the system is running. The addition is preferably carried out, for
example, before the draw solution flow d is introduced into the
unit A of the first step or before it is introduced into the unit B
of the second step, but is not limited thereto.
[0130] Depending on the type of the feedstock solution flow a and
the intended application of concentrated feedstock solution flow c,
prevention of the transfer of the common solute Xn from feedstock
solution flow a to draw solution flow d at arbitrary times during
system operation may be desired. In such a case, the present
invention includes an embodiment in which, for example, first,
operation is started with a draw solution flow d consisting of the
draw substance Xm and solvent b, and a common solute Xn of
predetermined concentration is added to the draw solution flow d
prior to the time at which the prevention of the transfer of common
solute Xn is desired.
<First Step>
[0131] In the first step of the feedstock flow concentration system
of the present invention, a forward osmosis process is carried out
using the unit A, the interior space of which is separated into two
including the feedstock solution flow-side space R and the draw
solution flow-side space D, by the forward osmosis membrane o.
<Forward Osmosis Membrane o of Forward Osmosis Unit)
[0132] The forward osmosis membrane o of the unit a is a membrane
which has a function of allowing the solvent b to permeate but
preventing or inhibiting permeation of the solute.
[0133] Examples of the form of the forward osmosis membrane o
include a hollow-fiber form, a flat membrane form, and a spiral
membrane form.
[0134] The forward osmosis membrane o is preferably a composite
membrane having an active separation layer on a support layer
(support membrane). The support membrane may be a flat membrane or
a hollow fiber membrane.
[0135] When a flat membrane is used as the support membrane, the
support membrane may have an active separation layer on one side or
both sides thereof.
[0136] When a hollow fiber membrane is used as a support membrane,
it may have an active separation layer on the outer surface or the
inner surface of the hollow fiber membrane, or on both
surfaces.
[0137] The support membrane of the present embodiment is a membrane
on which the active separation layer is supported, and it is
preferable that the support membrane itself not substantially
exhibit separation performance with respect to the object to be
separated. As the support membrane, any known microporous support
membrane or non-woven fabric can be used.
[0138] The preferred support membrane of the present embodiment is
a microporous hollow fiber support membrane. The microporous hollow
fiber support membrane has fine pores having a pore diameter of
preferably 0.001 .mu.m to 0.1 .mu.m, and more preferably 0.005
.mu.m to 0.05 .mu.m on the inner surface thereof. Regarding the
structure from the inner surface of the microporous hollow fiber
support membrane to the outer surface in the depth direction of the
membrane, in order to reduce the permeation resistance of the
permeating fluid, it is preferable that the structure be as sparse
as possible while maintaining strength. The sparse structure of
this portion is preferably, for example, a net-like structure,
finger-like voids, or a mixed structure thereof.
[0139] The material of the support membrane, particularly the
microporous support membrane, may be a material which can be molded
as a microporous support membrane and is not chemically damaged by
the monomer or solvent used to form the active separation layer,
but is not particularly limited. In the present embodiment, those
capable of forming into a hollow fiber-like microporous support
membrane are preferable.
[0140] As the material of the support membrane, for example, a
material composed of at least one selected from polyether sulfone,
polysulfone, polyketone, polyetheretherketone, polyphenylene ether,
polyvinylidene fluoride, polyacrylonitrile, polyimine, polyimide,
polybenzoxazole, polybenzimidazole, and polyamide as a main
component is preferable. A main component of at least one selected
from polysulfone and polyether sulfone is more preferable, and
using polyethersulfone is particularly preferable.
[0141] As an active separation layer in the flat or hollow
fiber-like forward osmosis membrane o, for example, a layer
composed of a thin polymer membrane containing at least one
selected from polysulfone, polyether sulfone, polyvinylidene
fluoride, polyacrylonitrile, polyethylene, polypropylene,
polyamide, and cellulose acetate as a main component is preferable
since the suppression rate of draw substance is high. A main
component of at least one selected from polysulfone, polyether
sulfone, polyvinylidene fluoride, polyacrylonitrile, and polyamide
is more preferable, and a polyamide layer is particularly
preferable.
[0142] The polyamide in the active separation layer can be formed
by interfacial polymerization of a polyfunctional acid halide and a
polyfunctional aromatic amine.
[0143] The polyfunctional aromatic acid halide is an aromatic acid
halide compound having two or more acid halide groups in one
molecule. Specific examples thereof include trimesic acid halide,
trimellitic acid halide, isophthalic acid halide, terephthalic acid
halide, pyromellitic acid halide, benzophenone tetracarboxylic acid
halide, biphenyldicarboxylic acid halide, naphthalenedicarboxylic
acid halide, pyridinedicarboxylic acid halide, and
benzenedisulfonic acid halide and these can be used alone or as a
mixture thereof. Examples of the halide ion in these aromatic acid
halide compounds include chloride ions, bromide ions, and iodide
ions. In the present invention, in particular, trimesic acid
chloride alone, a mixture of trimesic acid chloride and isophthalic
acid chloride, or a mixture of trimesic acid chloride and
terephthalic acid chloride is preferably used.
[0144] Polyfunctional aromatic amines are aromatic amino compounds
having two or more amino groups in one molecule. Specific examples
thereof include m-phenylenediamine, p-phenylenediamine,
3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylamine,
4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether,
3,3'-diaminodiphenylamine, 3,5-diaminobenzoic acid,
4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone,
3,4'-diaminodiphenyl sulfone, 1,3,5-triaminobenzene, and
1,5-diaminonaphthalene, and these may be used along or as a mixture
thereof. In the present invention, in particular, one or more
selected from m-phenylenediamine and p-phenylenediamine can
suitably be used.
[0145] Interfacial polymerization of the polyfunctional acid halide
and the polyfunctional aromatic amine can be carried out according
to a known method.
[0146] Nanoparticles, vesicles, and coating agents may be contained
on the surface or interior or both of the support membrane and the
molecular active layer constituting the forward osmosis membrane of
the present embodiment.
[0147] Examples of nanoparticles include open-ended carbon
nanotubes, closed-ended carbon nanotubes, carbon fibers,
nanofibers, nanowires, nanorods, nanotubes, and metal
nanoparticles; [0148] examples of vesicles include liposomes,
polymersomes, and self-assembled nanostructures (e.g.,
self-assemblies including certain transmembrane proteins and
detergents); and [0149] examples of coating agents include graphene
oxide, polyvinyl alcohol, silver-supported polymers, polydopamine,
polyvinylpyrrolidone, poly(2-hydroxyethyl methacrylate),
cyclodextrin, and silsesquioxane.
[0150] In the present embodiment, a hollow fiber-like forward
osmosis membrane is preferably used, and in particular, a composite
hollow fiber having an active separation layer composed of a thin
polymer membrane on an inner surface of a hollow fiber-like porous
support membrane is preferably used.
[0151] As the unit A, a unit in the form of a forward osmosis
membrane module in which a fiber bundle of a plurality of forward
osmosis membranes is preferably housed in a suitable housing is
preferably used.
[0152] The permeability flux for the solvent b of the forward
osmosis membrane o is preferably 1 to 100 kg/(m.sup.2.times. hr).
If the permeability flux is less than 1 kg/(m.sup.2.times. hr), the
solvent b separation efficiency may be impaired, and if it exceeds
100 kg/(m.sup.2.times. hr), the transfer amount of the draw
substance Xm from the draw solution flow d to the concentrated
feedstock solution flow c via the forward osmosis membrane o may
increase.
[0153] The permeability flux for the solvent b as used herein means
an amount obtained by assigning the amount of the solvent b passing
through the forward osmosis membrane o per unit area of the forward
osmosis membrane o and per unit time, and is defined by the
following formula (1):
F=L/(M.times.H) (1)
[0154] where F is the permeability flux (kg/(m.sup.2.times. hr))
for solvent b, L is the amount of solvent b permeated (kg), M is
the surface area (m.sup.2) of the forward osmosis membrane o, and H
is the time (hr).
[0155] The permeability flux when the solvent b is water is
generally referred to as "water permeability", and can be measured
using, for example, pure water as a treatment liquid and 3.5% by
mass saline as the draw solution flow.
(Introduction of Feedstock Solution Flow a and Draw Solution Flow d
into Unit A)
[0156] The feedstock solution flow a, which is the object to be
concentrated, is introduced into the feedstock solution flow-side
space R of the unit A, and the draw solution flow d is introduced
into the draw solution flow-side space D. The directions of these
flows may be counterflow or parallel flow.
[0157] Though the flow rate of the feedstock solution flow a
introduced into the feedstock solution flow-side space R of the
unit A is arbitrary, a typical example includes the range of 50
mL/(m.sup.2min) to 1500 mL/(m.sup.2min) per m.sup.2 surface area of
the forward osmosis membrane in the unit A per minute, and is
preferably set to 100 mL/(m.sup.2min) to 1000 mL/(m.sup.2min).
[0158] Though the flow rate of the draw solution flow d introduced
into the draw solution flow-side space D of unit A is arbitrary, an
example thereof includes the range of 100 mL/(m.sup.2min) to 5000
mL/(m.sup.2min), and is preferably set to 500 mL/(m.sup.2min) to
2000 mL/(m.sup.2min)
(Temperatures of Feedstock Solution Flow a and Draw Solution Flow
d)
[0159] In the first step, the temperature of the feedstock solution
flow a introduced into the feedstock solution flow-side space R of
the unit A is not particularly limited. It is not necessary to
specifically control the temperature. The temperature may be, for
example, room temperature.
[0160] The temperature of the draw solution flow d introduced into
the draw solution flow-side space D of the unit A is not
particularly limited, but is preferably 5.degree. C. to 60.degree.
C., and more preferably 15.degree. C. to 40.degree. C. Though the
reason is not clear, when the temperature of the draw solution flow
d is less than 15.degree. C. or higher than 60.degree. C., in some
cases, the amount of the draw substance Xm transferred from the
draw solution flow d to the feedstock solution flow a via the
forward osmosis membrane o is increased.
(Second Step)
[0161] The second step optionally used in the solvent separation
system of the present embodiment is: a step of separating the
solvent b from the draw solution flow d to obtain a concentrated
draw solution flow f, which is the draw solution flow which has
been concentrated, and the solvent b.
[0162] In the step of separating the draw solution flow d into the
concentrated draw solution flow f and the solvent b, for example, a
distillation process, a forward osmosis process, or a membrane
distillation process can be used.
[0163] The distillation process is a step of adjusting the draw
solution flow d to a predetermined temperature, and then passing it
through a distillation column to obtain the solvent b from the top
of the column as well as obtaining a concentrated draw solution
flow f, which is the draw solution flow from which the solvent b
has removed and which has been concentrated, from the bottom of the
column.
[0164] The forward osmosis process is a step in which the draw
solution flow d is flowed through the forward osmosis membrane so
that the solvent b contained in the draw solution flow d passes
through the forward osmosis membrane and thereby separated into the
solvent b and the concentrated draw solution flow f, from which the
solvent b is removed.
[0165] The membrane distillation process may be carried out, for
example, by the configuration shown as the second step in FIG. 2.
In this case, the membrane distillation process is configured such
that the separation chamber is divided into the liquid phase L and
the gas phase G using the semipermeable membrane p, and the solvent
b contained in the draw solution flow d passes from the liquid
phase L through the semipermeable membrane to the gas phase G at
reduced pressure, whereby the draw solution flow d can be separated
into the solvent b and the concentrated draw solution flow f.
[0166] As a process in the second step, a forward osmosis process
using a forward osmosis membrane or a membrane distillation process
using a semipermeable membrane p is preferable in terms of small
facility size, and a membrane distillation process using a
semipermeable membrane p is more preferable in terms of suppressing
the transfer of the draw substance Xm from the draw solution flow d
to the solvent b.
(Semi-Permeable Membrane p of Membrane Distillation Process)
[0167] Examples of the shape of the semipermeable membrane p used
in the membrane distillation process include any shape selected
from the shapes exemplified above regarding the shape of the
forward osmosis membrane o in the first step, and specific examples
thereof include a hollow fiber shape, a flat membrane shape, and a
spiral membrane shape.
[0168] The semipermeable membrane p in the form of a flat membrane
may be composed of, for example, a single layer, or may have a
support layer and an active separation layer on the support layer.
The hollow fiber-like semipermeable membrane p may be, for example,
a hollow fiber composed of a single layer, or may have a hollow
fiber-like support layer and an active separation layer on an outer
surface or an inner surface, or both, of the support layer.
[0169] The material of the support layer and the active separation
layer in the semipermeable membrane p may be any material selected
from the materials exemplified above for the forward osmosis
membrane o in the first step.
[0170] The permeability flux for the solvent b of the semipermeable
membrane p is preferably 1 kg/(m.sup.2.times.hr) to 200
kg/(m.sup.2.times. hr). If the permeability flux is less than 1
kg/(m.sup.2.times. hr), efficient separation of the solvent b may
be impaired, and if it exceeds 200 kg/(m.sup.2.times. hr), the
transfer amount of the draw substance from the draw solution flow d
to the solvent b via the semipermeable membrane p may be
increased.
[0171] This permeability flux is defined in the same manner as the
permeability flux for solvent b of the forward osmosis membrane o
in the first step.
(Temperature of Draw Solution Flow d Introduced in Membrane
Distillation Process)
[0172] It is preferable that the temperature of the draw solution
flow d be adjusted to a range of 20.degree. C. to 90.degree. C.
prior to introduction into the liquid phase L. If this temperature
is less than 20.degree. C., the efficiency of separation of the
solvent b by membrane distillation may be impaired, and if it
exceeds 90.degree. C., the amount of the draw substance Xm
contained in the draw solution flow d transferred to solvent b via
the semipermeable membrane p may increase.
[0173] As the heat source for heating the draw solution flow d, for
example, a heat exchanger q1 can be used, or waste heat such as
from an industrial process can be used. When waste heat is utilized
as the heat source, the amount of energy newly consumed for
separation of the solvent b can be reduced, which is
preferable.
(Gas Phase G in Membrane Distillation Process)
[0174] It is preferable that the pressure of the gas phase G of the
unit B used in the membrane distillation process be reduced to a
predetermined pressure. The pressure of the gas phase G may be
appropriately set according to the scale of the device, the
concentration of the draw solution flow d, and the generation rate
of the desired solvent b, but is preferably set to, for example,
0.1 kPa to 80 kPa, and more preferably 1 kPa to 50 kPa.
[0175] Examples the vacuum device for reducing the pressure of the
gas phase G of the unit B include a diaphragm vacuum pump, a dry
pump, an oil rotary vacuum pump, an ejector, or an aspirator.
(Products of Second Step)
[0176] As a result of the second step, the solvent b is separated
from the draw solution flow d to produce the concentrated draw
solution flow f, which is the draw solution flow which has been
concentrated, and is discharged from the unit B.
[0177] The concentrated draw solution flow f can be mixed with the
diluted draw solution flow e to adjust to a predetermined
concentration and then reused as the draw solution flow d. Upon
reuse of the concentrated draw solution flow f, the temperature of
the concentrated draw solution flow f may be adjusted using a
cooling device q2. Examples of the cooling device q2 include a
chiller and a heat exchanger.
[0178] The solvent b separated from the draw solution flow d by the
second step may be reused if necessary.
<<Preparation and Use of Draw Solution Flow d>>
[0179] The feedstock solution flow concentration system of the
present invention may further include means for using, in the first
step and the second step, the draw solution flow d prepared by
mixing the diluted draw solution flow e obtained in the first step
and the concentrated draw solution flow f obtained in the second
step.
[0180] In the system of FIG. 2, the first step and the second step
are connected via a buffer tank. The buffer tank has a function of
mixing the diluted draw solution flow e obtained in the first step
and the concentrated draw solution flow f obtained in the second
step at an optimum mixing amount to prepare the draw solution flow
d.
[0181] The draw solution flow d prepared (regenerated) in the
buffer tank can be fed to the first step by a feed pump r1 and to
the second step by a feed pump r2 and used in the respective
steps.
[0182] As a result of such a configuration, the feedstock solution
flow concentration system of the present invention can continuously
supply the draw solution flow d to the unit A of the first step and
the unit B of the second step, and thus, concentration of the
feedstock solution flow using the forward osmosis membrane can be
continuously carried out for long periods of time.
EXAMPLES
[0183] Hereinafter, the present invention will be specifically
described based on the Examples, but the present invention is not
limited by the Examples.
[0184] The following Examples and Comparative Examples were carried
out using the feedstock solution flow concentration system having
the configuration shown in FIG. 2.
(Preparation of Feedstock Solution Flow Concentration System)
[0185] <Preparation of Unit a Having Forward Osmosis Membrane
o>
(Production of Hollow Fiber Support Membrane Module)
[0186] A polyether sulfone (product name: "Ultrason", manufactured
by BASF Co., Ltd.) was dissolved in a N-methyl-2-pyrrolidone
(manufactured by Wako Pure Chemical Industries, Ltd.) to prepare a
20% by mass hollow fiber spinning stock solution.
[0187] A wet hollow spinning machine equipped with a double
spinning port was filled with the above stock solution, and
extruded into a coagulation tank filled with water to form hollow
fibers by phase separation. The obtained hollow fibers were wound
on a winding machine. The obtained hollow fibers had an outer
diameter of 1.0 mm and an inner diameter of 0.7 mm, and the
diameter of micropores on the inner surface thereof was 0.05
.mu.m.
[0188] These hollow fibers were used as the microporous hollow
fiber support membrane.
[0189] A hollow fiber support membrane module having an effective
inner membrane surface area of 0.023 m.sup.2 was prepared by
filling 130 of the above hollow fiber support membranes into a
cylindrical plastic housing having a diameter of 2 cm and a length
of 10 cm and fixing both ends with an adhesive.
(Production of Unit A, Forward Osmosis Membrane Module)
[0190] 10 g of m-phenylenediamine and 0.08 g of sodium lauryl
sulfate were charged into a 0.5 L capacity vessel, and further
489.2 g of pure water was added for dissolution to prepare 0.5 kg
of a first solution used for interfacial polymerization.
[0191] 0.8 g of trimesic acid chloride was charged into a separate
1.0 L vessel, and 399.2 g of n-hexane was added for dissolution to
prepare 0.4 kg of a second solution used for interfacial
polymerization.
[0192] The core side (inside of the hollow fiber) of the hollow
fiber support membrane module manufactured in the "Production of
Hollow Fiber Support Membrane Module" above was filled with the
first solution, and after standing for 5 minutes, the liquid was
withdrawn, whereby the insides of the hollow fibers were wetted
with the first solution.
[0193] Thereafter, the core side pressure was set to normal
pressure by a core side pressure adjusting device, and the shell
side pressure was set to a reduced pressure of 90 kPa as an
absolute pressure by a shell side pressure adjusting device, and
left standing for 5 minutes in this state. Subsequently, on the
core side, an operation of passing nitrogen at a flow rate of 5
L/min for 5 minutes was carried out to remove the excess first
solution. While the pressure on the shell side was maintained at a
reduced pressure of 90 kPa as an absolute pressure, the second
solution was fed into the core side by a second solution feeding
pump at a flow rate of 50 mL/min for 2 minutes, and interfacial
polymerization was carried out. The polymerization temperature was
set at 25.degree. C.
[0194] Nitrogen was then flowed at 40.degree. C. through the core
side of the hollow fiber support membrane module for 1 min to
transpirate and remove n-hexane. Both the shell side and the core
side were washed with pure water to produce unit A, which is a
module of a hollow fiber-like forward osmosis membrane o having an
active separation layer composed of a polyamide on the inner
surface of the hollow fiber support membrane.
(Preparation of Unit B Having Semi-Permeable Membrane p for
Membrane Distillation Process)
[0195] 23 parts by mass of hydrophobic silica (product name
"AEROSIL-R972", manufactured by Nippon Aerosil Co., Ltd.) having an
average primary particle diameter of 0.016 .mu.m and a specific
surface area of 110 m.sup.2/g, 31 parts by mass of dioctyl
phthalate (DOP), and 6 parts by mass of dibutyl phthalate (DBP)
were mixed with a Henschel mixer, and thereafter 40 parts by mass
of polyvinylidene fluoride (product name "Solef 6010", manufactured
by SOLVAY Co., Ltd.) having a weight-average molecular weight of
310,000 was added thereto, and the mixture was mixed again with the
Henschel mixer to obtain a mixture. The mixture was pelletized with
a two-axis kneading extruder.
[0196] The obtained pellets were melt-kneaded with the two-axis
kneading extruder at 240.degree. C., and extruded into a hollow
fiber-like shape to obtain hollow fibers. At this time, a spinning
port for hollow fiber molding was mounted on the extrusion port in
the head of an extruder end, and kneading melt was extruded from an
annular hole for melt extrusion, and simultaneously, nitrogen gas
was ejected from a circular hole for discharging a hollow portion
forming fluid inside the annular hole for melt extrusion, thereby
extruding into a hollow fiber shape.
[0197] The hollow filament was introduced into a water bath
(40.degree. C.) at an empty running distance of 20 cm and wound at
a rate of 20 m/min.
[0198] The resulting hollow filaments were drawn continuously at a
rate of 20 m/min in a pair of first endless orbital belt drawers
and passed through a first heated bath (0.8 m length) controlled to
a space temperature of 40.degree. C., and then withdrawn at a rate
of 40 m/min in a second endless orbital belt withdrawer and
stretched 2.0 times in the length direction. After passing through
a second heating tank (0.8 m length) controlled to a space
temperature of 80.degree. C., the filaments were cooled while being
periodically folded at the water surface of a 20.degree. C. cooling
water tank. The drawn yarn was then withdrawn at a rate of 30 m/min
by a third endless orbital type belt drawer, and the drawn yarn was
shrunk (relaxed) to 1.5 times in the length direction, and then
wound with a skein (hank) having a circumferential length of
approximately 3 m. Periodic folding at the water surface of the
cooling water tank was carried out by continuously sandwiching the
hollow filaments at a rotation speed of 170 rpm using a pair of
convex/concave rollers having four protrusions and lengths of
approximately 0.20 m.
[0199] The hollow filaments after the above treatment were immersed
in methylene chloride to extract and remove DOP and DBP, and then
dried. The hollow filaments were then immersed in 50% by mass
aqueous ethyl alcohol solution, and then immersed in a 5% by mass
aqueous sodium hydroxide solution for 1 hour at 40.degree. C.,
thereby extracting and removing silica. Thereafter, the filaments
were washed with water and dried to obtain a hollow fiber membrane.
The obtained hollow fibers had an outer diameter of 1.25 mm and an
inner diameter of 0.68 mm, and the diameter of micropores on the
inner surface thereof was 0.1 .mu.m. These hollow fibers were used
as the semipermeable membrane.
[0200] By filling 70 semipermeable membranes composed of the above
hollow fibers into a cylindrical plastic housing having a diameter
of 2 cm and a length of 10 cm and fixing both ends with an
adhesive, unit B, which is a membrane distillation module having a
hollow fiber-like semipermeable membrane p having an effective
inner membrane surface area of 0.012 m.sup.2 was produced.
Comparative Example 1
[0201] In Comparative Example 1, the forward osmosis unit A
prepared above was used as unit A in the first step, and the
membrane distillation unit B produced above was used as unit B in
the second step.
[0202] Water was used as solvent b.
[0203] As the draw solution flow d, an aqueous solution containing
magnesium chloride as the draw substance Xm was used, and the
magnesium chloride concentration in the draw solution flow d was
set to 20% by mass.
[0204] As the feedstock solution flow a, an aqueous solution
containing sodium chloride was used, and the initial concentration
thereof was set to 5.0% by mass.
[0205] In the first step, the feedstock solution flow a was flowed
into unit A at a flow rate of 10 mL/min and the draw solution flow
d was flowed at a flow rate of 24 mL/min.
[0206] In the second step, the draw solution flow d was flowed into
unit B at a flow rate of 600 mL/min, and the pressure of the gas
phase G of unit B was adjusted with a vacuum pump to 10 kPa as an
absolute pressure.
[0207] The diluted draw solution flow e obtained in the first step
and the concentrated draw solution flow f obtained in the second
step were mixed in a buffer tank to prepare a draw solution and
reused in the first and second steps.
[0208] The temperature of the draw solution flow d in the unit A in
the first step was 25.degree. C., the temperature of the draw
solution flow d in the unit B in the second step was 65.degree. C.,
and by carrying out operation for 10 hours, concentration of the
feedstock solution flow a was carried out.
Comparative Examples 2 to 10
[0209] Concentration of the feedstock solution flow a was carried
out according to the same procedure as in Comparative Example 1,
except that the type and concentration of the draw substance Xm in
the draw solution flow d and the solute Xn in the feedstock
solution flow a were changed as described in Table 1.
Example 1
[0210] Concentration of the feedstock solution flow a was carried
out according to the same procedure as in Comparative Example 1,
except that a mixture obtained by adding sodium chloride at a
concentration of 4.8% by mass as common solute Xn with the
feedstock solution flow a together with magnesium chloride as the
draw substance Xm was used as the draw solution flow d.
Examples 2 to 15
[0211] Concentration of the feedstock solution flow a was carried
out according to the same procedure as in Example 1, except that
the type of the draw substance Xm in the draw solution flow d, and
the type and the concentration of the common solute Xn in the
feedstock solution flow a and the draw solution flow d were changed
as described in Table 2.
<<Evaluation>>
[0212] (1) Evaluation of Elution Suppression Performance of Solute
Xn in Feedstock Solution Flow a
[0213] The amount of cations (cations derived from solute Xn)
ionized from the solute Xn present in the feedstock solution flow a
discharged from the unit A was continuously measured using a ICP-MS
(Inductively Coupled High Frequency Plasma-Mass Spectrometry)
device manufactured by Thermo Fishier Scientific, Ltd., product
name "iCAP Q".
[0214] The permeate flow rate of the solute Xn in the unit A from
the start of the operation to the end of the operation was
calculated by the following formula (2). Note that the permeate
flow rate of the solute Xn was set as an amount per unit time of
the solute Xn-derived cation that has migrated from the feedstock
solution flow a into the draw solution flow d via the forward
osmosis membrane o.
F'=L'/(M'.times.H') (2)
[0215] where F' is the permeation flow rate [g/(m.sup.2.times. hr)]
of the solute Xn-derived cation, L' is the total amount (g) of the
permeated solute Xn-derived cation, M' is the surface area
(m.sup.2) of the forward osmosis membrane o, and H' is the
operation time (hr).
[0216] From the values of the permeate flow rate F' of the obtained
solute Xn, the solute elution suppression performances evaluated on
the basis of the following criteria are shown in Table 1. [0217] A:
the permeate flow rate of solute Xn was below the detectable limit
(0 [g/(m.sup.2.times. hr)]) (extremely good) [0218] B: the permeate
flow rate of solute Xn exceeded 0 [g/(m.sup.2.times. hr)] and is
3.8 [g/(m.sup.2.times. hr)] or less (suitable) [0219] C: the
permeate flow rate of solute Xn exceeded 3.8 [g/(m.sup.2.times.
hr)] (poor) (2) Evaluation of Solute Leakage Suppression
Performance by Common Solute into Draw Solution Flow d
[0220] Comparative Example 1 is an Example in which the common
solute Xn was not contained in the draw solution flow d of Examples
1 to 5,
[0221] Comparative Example 2 is an Example in which the common
solute Xn was not contained in the draw solution flow d of Example
6,
[0222] Comparative Example 3 is an Example in which the draw
solution flow d did not contain the common solute Xn of Examples 7
and 8, and
[0223] Comparative Examples 4 to 10 are Examples in which no common
solute Xn was contained in the draw solution flow d of Examples 9
to 15, respectively.
[0224] Regarding the corresponding combinations of the Examples and
Comparative Examples, the case in which the common solute Xn was
contained in the draw solution flow d and the case in which it was
not contained were compared by the following indicators.
[0225] Using the value of the permeate flow rate F' of the solute
Xn calculated by the above formula (2), the value of F' in the
Examples was set as "F'1", and the value of F' in the Comparative
Examples corresponding to the Examples was set as "F'0", and the
solute leakage suppression performance value Z1 due to the common
solute inclusion was calculated by the following formula (3) and
evaluated on the basis of the following criteria.
Z1={F'1/F'0}.times.100(%) (3)
(Evaluation Criteria)
[0226] AA: the value of Z1 was 60% or less (extremely good) [0227]
A: the value of Z1 was greater than 60% and less than 80%
(suitable) [0228] B: the value of Z1 was greater than 80% and less
than 95% (acceptable) [0229] C: the value of Z1 exceeded 95%.
[0230] The evaluation results of the Comparative Examples are shown
in Table 1, and the evaluation results of the Examples are shown in
Table 2.
TABLE-US-00001 TABLE 1 Comp Comp Comp Comp Comp Comp Comp Comp Comp
Comp Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Ex 10 Draw Draw
Type MgCl.sub.2 KCl MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2
MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 Solution Substance
Concentration 20 20 20 20 20 20 20 20 20 20 Flow d Xm (mass %)
Feedstock Solute Xn Type NaCl NaCl NaCl, KCl CaCl.sub.2 KBr
NH.sub.4Cl KHCO.sub.3 K.sub.2SO.sub.4 NaNO.sub.3 Solution KCl Flow
a Initial 5.0 5.0 5.0, 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0
Concentration (mass %) Unit A Elution Suppression C C C, C C C C C
C C C Performance of Solute Xn
(the end of TABLE 1)
TABLE-US-00002 [0231] TABLE 2 Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex
8 Draw Draw Type MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2
MgCl.sub.2 KCl MgCl.sub.2 MgCl.sub.2 Solution Substance
Concentration 20 20 20 20 20 20 20 20 Flow d Xm (mass %) Common
Type NaCl NaCl NaCl NaCl NaCl NaCl NaCl, KCl NaCl, KCl Solute Xn
Concentration 4.8 2.3 1.2 0.3 0.05 2.3 2.3, 0.0 2.3, 2.9 (mass %)
Feedstock Common Type NaCl NaCl NaCl NaCl NaCl NaCl NaCl, KCl NaCl,
KCl Solution Solute Xn Initial 5.0 5.0 5.0 5.0 5.0 5.0 5.0, 5.0
5.0, 5.0 Flow a Concentration (mass %) Unit A Elution Suppression A
A B B B A A, C A, A Performance of Common Solute Xn Common Solute
Corresponding Comp Comp Comp Comp Comp Comp Comp Comp Comp Elution
Ex No. Ex 1 Ex 1 Ex 1 Ex 1 Ex 1 Ex 2 Ex 3 Ex 3 Suppression Eval
Results AA AA AA AA B AA AA, C AA, AA Performance Ex 9 Ex 10 Ex 11
Ex 12 Ex 13 Ex 14 Ex 15 Draw Draw Type MgCl.sub.2 MgCl.sub.2
MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 Solution
Substance Concentration 20 20 20 20 20 20 20 Flow d Xm (mass %)
Common Type KCl CaCl.sub.2 KBr NH.sub.4Cl KHCO.sub.3
K.sub.2SO.sub.4 NaNO.sub.3 Solute Xn Concentration 2.9 2.4 2.8 3.0
1.5 2.4 4.2 (mass %) Feedstock Common Type KCl CaCl.sub.2 KBr
NH.sub.4Cl KHCO.sub.3 K.sub.2SO.sub.4 NaNO.sub.3 Solution Solute Xn
Initial 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Flow a Concentration (mass %)
Unit A Elution Suppression A A A A A A A Performance of Common
Solute Xn Common Solute Corresponding Comp Comp Comp Comp Comp Comp
Comp Comp Elution Ex No. Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Ex 10
Suppression Eval Results AA AA AA AA AA AA AA Performance
(the end of TABLE 2)
Comparative Example 11
[0232] Comparative Example 11 was carried out using the feedstock
solution flow concentration system shown in FIG. 1. The forward
osmosis unit A prepared above was used as the unit A in the first
step.
[0233] Water was used as the solvent b.
[0234] As the draw solution flow d, an aqueous solution containing
magnesium chloride as the draw substance Xm was used, and the
magnesium chloride concentration in the initial draw solution flow
d was set to 25% by mass.
[0235] As the feedstock solution flow a, an aqueous solution
containing ethanol as the solute Xn was used, and the initial
concentration thereof was set to 5.0% by mass.
[0236] In the feedstock solution flow concentration system shown in
FIG. 1, the feedstock solution flow a was flowed at a flow rate of
120 mL/min and the draw solution flow d was flowed at a flow rate
of 236 mL/min into unit A in the first step.
[0237] The diluted draw solution flow e was circulated with a
circulation pump and supplied again as the draw solution flow
d.
[0238] The temperatures of the feedstock solution flow a in the
unit A in the first step and the draw solution flow d were
25.degree. C., and by carrying out operations for 5 hours,
concentration of the feedstock solution flow a was carried out.
Comparative Examples 12 to 20
[0239] Concentration of the feedstock solution flow a was carried
out according to the same procedure as in Comparative Example 11,
except that the types and concentrations of the draw substance Xm
in the draw solution flow d and the solute Xn in the feedstock
solution flow a were changed as described in Table 3.
Example 16
[0240] Concentration of the feedstock solution flow a was carried
out according to the same procedure as in Comparative Example 11,
except that ethanol was added at a concentration of 1.0% by mass as
the common solute Xn in the feedstock solution flow a together with
magnesium chloride as the draw substance Xm in the draw solution
flow d.
Examples 17 to 27 and Comparative Examples 21 to 23
[0241] Concentration of the feedstock solution flow a was carried
out according to the same procedure as in Example 16, except that
the type of the draw substance Xm in the draw solution flow d, and
the type and the concentration of the common solute Xn in the
feedstock solution flow a and the draw solution flow d were changed
as described in Table 4.
[0242] Note that, even when the common solute Xn is difficult to
dissolve in the draw solution flow d, the solution was well
stirred, and the concentration of the feedstock solution flow a was
evaluated by carrying out the concentration of the feedstock
solution flow a while keeping the concentration as uniform as
possible.
<<Evaluation>>
[0243] Regarding the concentration of the feedstock solution flow a
carried out in Comparative Examples 11 to 23 and Examples 16 to 27
described above, (1) evaluation of the elution suppressing
performance of the solute Xn in the feedstock solution flow a, and
(2) evaluation of the solute leakage suppressing performance due to
the common solute content in the draw solution flow d were carried
out in the same manner as in Comparative Example 1, except that the
measurement of the amount of the solute Xn was carried out as
follows.
[0244] The amount of solute Xn present in the diluted draw solution
flow e discharged from the unit A was measured as follows,
depending on whether the solute Xn was an organic substance or an
inorganic salt.
[0245] When the solute Xn was an organic substance: [0246] i) The
case of one type of organic substance [0247] The amount of solute
Xn was measured as the total organic carbon amount (TOC) using a
commercially available TOC measuring device ("TOC-5000"
manufactured by Shimadzu Corporation) [0248] ii) The case of a
plurality of types of organic substances [0249] In addition to the
TOC measurement, nuclear magnetic resonance (NMR; model number
"ECS-400", manufactured by Japan Electronics Co., Ltd.), and gas
chromatography mass analysis (GC/MS, model number "HP6890/5973"
manufactured by Agilent Co., Ltd.) were used for measurement, as
appropriate, to quantify each component.
[0250] When the solute Xn was an inorganic salt: measurement was
carried out by the same method as in Comparative Example 1.
[0251] The evaluation results of Comparative Examples 11 to 20 are
shown in Table 3, and the evaluation results of Examples 16 to 27
and Comparative Examples 21 to 23 are shown in Table 4.
[0252] In Table 3 and Table 4, abbreviations in the solute or
common solute column have the following meanings. [0253] EtOH:
Ethanol [0254] IPA: Isopropanol [0255] EtOAc: Ethyl acetate [0256]
.beta.-Cit: .beta.-citronellol [0257] AcCin: Cinnamyl acetate
[0258] AN: Acetonitrile [0259] Ser: L-serine
[0260] "Backflow" in the table means that the total amount of the
common solute Xn in the feedstock solution flow a after
concentration exceeded the total amount of the common solute Xn in
the feedstock solution flow a before concentration.
TABLE-US-00003 TABLE 3 Comp Comp Comp Comp Comp Comp Comp Comp Comp
Comp Ex 11 Ex 12 Ex 13 Ex 14 Ex 15 Ex 16 Ex 17 Ex 18 Ex 19 Ex 20
Draw Draw Type MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2
MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2
Solution Substance Concentration 25 25 25 25 25 25 25 25 25 25 Flow
d Xm (mass %) Feedstock Common Type EtOH IPA EtOAc .beta.-Cit AcCin
AN Ser IPA, AN, IPA, NaCl IPA, KCl Solution Solute Xn Ser Flow a
Initial 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0, 5.0, 5.0, 5.0 5.0, 5.0
Concentration 5.0 (mass %) Unit A Elution Suppression C C C C C C C
C, C, C C, C C, C Performance of Common Solute Xn
(the end of TABLE 3)
TABLE-US-00004 [0261] TABLE 4 Comp Ex 16 Ex 17 Ex 21 Ex 18 Ex 19 Ex
20 Ex 21 Ex 22 Draw Draw Type MgCl.sub.2 MgCl.sub.2 MgCl.sub.2
MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 Solution
Substance Concentration 25 25 25 25 25 25 25 25 Flow d Xm (mass %)
Common Type EtOH EtOH IPA IPA IPA IPA IPA EtOAc Solute Xn
Concentration 1.0 4.5 0.001 0.05 0.15 0.3 4.5 4.0 (mass %)
Feedstock Common Type EtOH EtOH IPA IPA IPA IPA IPA EtOAc Solution
Solute Xn Initial 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Flow a
Concentration (mass %) Unit A Elution Suppression B A C B B B A A
Performance of Common Solute Xn Common Solute Corresponding Comp
Comp Comp Comp Comp Comp Comp Comp Comp Elution Ex No. Ex 11 Ex 11
Ex 12 Ex 12 Ex 12 Ex 12 Ex 12 Ex 13 Suppression Eval Results A AA C
B B A AA AA Performance Comp Comp Ex 23 Ex 24 Ex 25 Ex 26 Ex 27 Ex
22 Ex 23 Draw Draw Type MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 MgCl.sub.2
MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 Solution Substance Concentration
25 25 25 25 25 25 25 Flow d Xm (mass %) Common Type .beta.-Cit
AcCin AN Ser IPA, AN, IPA, NaCl IPA, KCl Solute Xn Ser
Concentration 4.95 1.5 4.0 4.0 1.5, 5.0, 4.6 5.5, 2.9 (mass %) 4.0,
4.0 Feedstock Common Type .beta.-Cit AcCin AN Ser IPA, AN, IPA,
NaCl IPA, KCl Solution Solute Xn Ser Flow a Initial 5.0 5.0 5.0 5.0
5.0, 5.0, 5.0 5.0, 5.0 Concentration 5.0, 5.0 (mass %) Unit A
Elution Suppression A A A A A, A, A Backflow, Backflow, Performance
of A A Common Solute Xn Common Solute Corresponding Comp Comp Comp
Comp Comp Comp Comp Comp Elution Ex No. Ex 14 Ex 15 Ex 16 Ex 17 Ex
18 Ex 19 Ex 20 Suppression Eval Results AA AA AA AA AA, AA,
Backflow, Backflow, Performance AA AA AA
(the end of TABLE 4)
Comparative Example 24
[0262] In Comparative Example 24, enrichment of red wine was
carried out using the feedstock solution flow concentration system
shown in FIG. 1.
[0263] The forward osmosis unit A produced above was used as unit A
of the first step.
[0264] As the feedstock solution flow a, commercially available red
wine (ethanol (EtOH) content=12.0% by volume) was used as-is. Thus,
the solvent b of the feedstock solution flow a was water. Water was
used as the solvent b of the induction liquid stream d.
[0265] As the draw solution flow d, an aqueous solution containing
magnesium chloride was used as the draw substance Xm, and the
magnesium chloride concentration in the initial draw solution flow
d was set to 32% by mass.
[0266] In the feedstock solution flow concentration system shown in
FIG. 1, in the first step, the feedstock solution flow a was flowed
at a flow rate of 120 mL/min and the draw solution flow d was
flowed at a flow rate of 236 mL/min into unit A.
[0267] The diluted draw solution flow e was then circulated with a
circulation pump and re-supplied as the draw solution flow d
as-is.
[0268] The temperatures of the feedstock solution flow a in the
unit A in the first step and the draw solution flow d were
10.degree. C., and operation was carried out for 1 hour.
Comparative Example 25
[0269] Concentration of the feedstock solution flow a was carried
out according to the same procedure as in Comparative Example 24,
except that ethanol was added at a concentration of 20% by volume
as the common solute Xn in the feedstock solution flow a together
with magnesium chloride as the draw substance Xm in the draw
solution flow d.
Example 28
[0270] As the draw solution flow d, an aqueous solution obtained by
adding magnesium chloride having a concentration of 32 mass % as
the draw substance Xm and the same red wine as the feedstock
solution flow a was used, and all of the types of solute in the red
wine were defined as the common solute Xn. The amount of red wine
added to the draw solution flow d was set to be 2.0% by volume in
terms of ethanol.
<<Evaluation>>
[0271] (1) Evaluation of Solute Leakage Suppression Performance by
Common Solute into Draw Solution Flow d
[0272] Comparative Example 25 and Example 28 correspond to the case
where the common solute Xn was contained in the draw solution flow
d of Comparative Example 24. Therefore, for Comparative Example 25
and Example 28, with reference to Comparative Example 24,
evaluation of the solute leakage suppressing performance due to the
common solute content into the draw solution flow d was carried out
by the following method.
[0273] Each value of F' was obtained by carrying out "(1)
Evaluation of Elution Suppression Performance of Solute Xn in
Feedstock Solution Flow a" in the same manner as in Example 16,
except that with respect to the concentration of the feedstock
solution flow a (red wine), ethanol was selected as the solute Xn,
measurement of the amount was carried out by a method described
later, and the evaluation criteria were changed as follows. Using
the value of Z1 calculated by formula (2) in "(2) Evaluation of
Solute Leakage Suppression Performance due to Common Solute
Inclusion into Draw Solution Flow d" in Example 16, evaluation was
carried out by the following criteria. [0274] A: the value of Z1
was 80% or less (suitable) [0275] C: the value of Z1 was greater
than 80% and less than or equal to 100% (poor) [0276] Backflow: the
value of Z1 exceeded 100% (extremely poor)
(2) Evaluation of Solute Component Balance Maintenance
[0277] Seven solute components, ethanol, and six organic acids
(tartaric, citric, malic, lactic, succinic, and acetic acids), were
selected as solutes in red wine.
[0278] Before and after concentration of red wine, the
concentrations of these seven components were measured by a method
described later to determine the composition ratio. This
composition ratio was based on mass, and was determined as a value
normalized so that the sum of the seven components was 100. Thus,
for the red wine before concentration and after concentration, the
mass ratio of each component was calculated in units of percentage
(%).
[0279] For each component, a difference (% pt) between the mass
ratio (%) before concentration and the mass ratio (%) after
concentration was determined and evaluated by the following
criteria. [0280] A: for all seven components, the difference in the
mass ratio (%) before and after concentration was 5 (% pt) or less
(suitable) [0281] C: there is one or more components with a
difference in mass ratio (%) of more than 5 (% pt) before and after
concentration (poor)
[0282] Analysis of the amount of ethanol in "(1) Evaluation of
Solute Leakage Suppression Performance by Common Solute into Draw
Solution Flow d" and "(2) Evaluation of Solute Component Balance
Maintenance" described above was carried out using a rapid alcohol
measurement kit manufactured by Kyoto Electronics Industry Co.,
Ltd., and a product name "SD-700", respectively.
[0283] Analysis of the amount of organic acid in "(2) Evaluation of
Solute Component Balance Maintenance" described above was carried
out with a calibration curve method using an HPLC.
(3) Sensory Evaluation
[0284] Pure water was added to each of the concentrated red wines
(concentrated feedstock solution flow c) obtained in Comparative
Examples 24 and 25 and Example 28 for dilution so that the ethanol
concentration became a numerical value (12.0% by volume) before
concentration to obtain a concentrated reduced red wine.
[0285] Six evaluators were allowed to taste these concentrated
reduced red wines and pre-concentrated red wines to assess
astringency, sweetness, and maintenance of alcohol balance, and the
wines were evaluated on the following criteria: [0286] 3 points:
the balance between astringency, sweetness, and alcohol was
maintained [0287] 1 point: the balance between astringency and
sweetness was maintained, but the balance of alcohol was lost
[0288] 0 points: the balance between astringency, sweetness, and
alcohol was lost
[0289] For each of the Comparative Examples and the Examples, the
total score obtained by adding the scores of the six evaluators was
evaluated on the basis of the following criteria. [0290] A: A total
score of 15 points or more (good) [0291] B: A total score of 10
points to 14 points (poor) [0292] C: A total score of 9 points or
less (extremely poor)
[0293] The above results are shown in Table 5.
TABLE-US-00005 TABLE 5 Comp Ex 24 Comp Ex 25 Ex 28 Draw Draw Type
MgCl.sub.2 MgCl.sub.2 MgCl.sub.2 Solution Substance Concentration
32 32 32 Flow d Xm (mass %) Common Type -- EtOH Total Common Solute
Xn Solute in Red Wine Concentration -- 20.0 EtOH Conversion (vol %)
2.0 Feedstock Feedstock Solution Type Red Wine Red Wine Red Wine
Solution Typical Type EtOH EtOH EtOH Flow a Common Initial 12.0
12.0 12.0 Solute Xn Concentration (vol %) Common Solute
Corresponding Comp Ex No. -- Comp Comp Elution Ex 24 Ex 24
Suppression Eval Results -- C A Performance Component Balance
Maintenance C C A Sensory Evaluation C B A
(the end of TABLE 5)
REFERENCE SIGN LISTS
[0294] a feedstock solution flow [0295] b solvent [0296] c
concentrated feedstock solution flow [0297] d draw solution flow
[0298] e diluted draw solution flow [0299] f concentrated draw
solution flow [0300] Xn common solute [0301] Xm draw substance
[0302] forward osmosis membrane [0303] p semipermeable membrane
[0304] q1 heat exchanger [0305] q2 cooling device [0306] r1, r2
feed pump [0307] D draw solution flow-side space [0308] G gas phase
[0309] L liquid phase [0310] R feedstock solution flow-side
space
* * * * *