WO2018173330A1 - Drawing agent for forward osmosis and pressure retarded osmosis and a system using the same - Google Patents
Drawing agent for forward osmosis and pressure retarded osmosis and a system using the same Download PDFInfo
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- WO2018173330A1 WO2018173330A1 PCT/JP2017/033661 JP2017033661W WO2018173330A1 WO 2018173330 A1 WO2018173330 A1 WO 2018173330A1 JP 2017033661 W JP2017033661 W JP 2017033661W WO 2018173330 A1 WO2018173330 A1 WO 2018173330A1
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- main chain
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- metal salt
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- 238000009292 forward osmosis Methods 0.000 title description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 209
- 150000003839 salts Chemical group 0.000 claims abstract description 167
- 239000012528 membrane Substances 0.000 claims abstract description 111
- 229910052751 metal Inorganic materials 0.000 claims abstract description 104
- 239000002184 metal Substances 0.000 claims abstract description 104
- 150000001875 compounds Chemical class 0.000 claims abstract description 85
- 230000003204 osmotic effect Effects 0.000 claims abstract description 76
- 125000002843 carboxylic acid group Chemical class 0.000 claims abstract description 70
- ABLZXFCXXLZCGV-UHFFFAOYSA-N phosphonic acid group Chemical class P(O)(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 claims abstract description 62
- 229910017053 inorganic salt Inorganic materials 0.000 claims abstract description 19
- 239000007864 aqueous solution Substances 0.000 claims abstract description 11
- 238000005192 partition Methods 0.000 claims abstract description 4
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 20
- QPCDCPDFJACHGM-UHFFFAOYSA-N N,N-bis{2-[bis(carboxymethyl)amino]ethyl}glycine Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(=O)O)CCN(CC(O)=O)CC(O)=O QPCDCPDFJACHGM-UHFFFAOYSA-N 0.000 claims description 11
- 230000005611 electricity Effects 0.000 claims description 11
- 125000000217 alkyl group Chemical group 0.000 claims description 10
- 229960003330 pentetic acid Drugs 0.000 claims description 10
- 150000001413 amino acids Chemical class 0.000 claims description 8
- 125000000524 functional group Chemical group 0.000 claims description 8
- 229910052739 hydrogen Inorganic materials 0.000 claims description 8
- DUYCTCQXNHFCSJ-UHFFFAOYSA-N dtpmp Chemical compound OP(=O)(O)CN(CP(O)(O)=O)CCN(CP(O)(=O)O)CCN(CP(O)(O)=O)CP(O)(O)=O DUYCTCQXNHFCSJ-UHFFFAOYSA-N 0.000 claims description 6
- SZHQPBJEOCHCKM-UHFFFAOYSA-N 2-phosphonobutane-1,2,4-tricarboxylic acid Chemical compound OC(=O)CCC(P(O)(O)=O)(C(O)=O)CC(O)=O SZHQPBJEOCHCKM-UHFFFAOYSA-N 0.000 claims description 5
- VKZRWSNIWNFCIQ-WDSKDSINSA-N (2s)-2-[2-[[(1s)-1,2-dicarboxyethyl]amino]ethylamino]butanedioic acid Chemical compound OC(=O)C[C@@H](C(O)=O)NCCN[C@H](C(O)=O)CC(O)=O VKZRWSNIWNFCIQ-WDSKDSINSA-N 0.000 claims description 4
- URDCARMUOSMFFI-UHFFFAOYSA-N 2-[2-[bis(carboxymethyl)amino]ethyl-(2-hydroxyethyl)amino]acetic acid Chemical compound OCCN(CC(O)=O)CCN(CC(O)=O)CC(O)=O URDCARMUOSMFFI-UHFFFAOYSA-N 0.000 claims description 4
- DMQQXDPCRUGSQB-UHFFFAOYSA-N 2-[3-[bis(carboxymethyl)amino]propyl-(carboxymethyl)amino]acetic acid Chemical compound OC(=O)CN(CC(O)=O)CCCN(CC(O)=O)CC(O)=O DMQQXDPCRUGSQB-UHFFFAOYSA-N 0.000 claims description 4
- WYMDDFRYORANCC-UHFFFAOYSA-N 2-[[3-[bis(carboxymethyl)amino]-2-hydroxypropyl]-(carboxymethyl)amino]acetic acid Chemical compound OC(=O)CN(CC(O)=O)CC(O)CN(CC(O)=O)CC(O)=O WYMDDFRYORANCC-UHFFFAOYSA-N 0.000 claims description 4
- 229940120146 EDTMP Drugs 0.000 claims description 4
- JYXGIOKAKDAARW-UHFFFAOYSA-N N-(2-hydroxyethyl)iminodiacetic acid Chemical compound OCCN(CC(O)=O)CC(O)=O JYXGIOKAKDAARW-UHFFFAOYSA-N 0.000 claims description 4
- YDONNITUKPKTIG-UHFFFAOYSA-N [Nitrilotris(methylene)]trisphosphonic acid Chemical compound OP(O)(=O)CN(CP(O)(O)=O)CP(O)(O)=O YDONNITUKPKTIG-UHFFFAOYSA-N 0.000 claims description 4
- NFDRPXJGHKJRLJ-UHFFFAOYSA-N edtmp Chemical compound OP(O)(=O)CN(CP(O)(O)=O)CCN(CP(O)(O)=O)CP(O)(O)=O NFDRPXJGHKJRLJ-UHFFFAOYSA-N 0.000 claims description 4
- DEFVIWRASFVYLL-UHFFFAOYSA-N ethylene glycol bis(2-aminoethyl)tetraacetic acid Chemical compound OC(=O)CN(CC(O)=O)CCOCCOCCN(CC(O)=O)CC(O)=O DEFVIWRASFVYLL-UHFFFAOYSA-N 0.000 claims description 4
- MGFYIUFZLHCRTH-UHFFFAOYSA-N nitrilotriacetic acid Chemical compound OC(=O)CN(CC(O)=O)CC(O)=O MGFYIUFZLHCRTH-UHFFFAOYSA-N 0.000 claims description 4
- 239000004475 Arginine Substances 0.000 claims description 2
- 229910052783 alkali metal Inorganic materials 0.000 claims description 2
- 150000001340 alkali metals Chemical class 0.000 claims description 2
- ODKSFYDXXFIFQN-UHFFFAOYSA-N arginine Natural products OC(=O)C(N)CCCNC(N)=N ODKSFYDXXFIFQN-UHFFFAOYSA-N 0.000 claims description 2
- 230000006698 induction Effects 0.000 claims description 2
- 235000002639 sodium chloride Nutrition 0.000 description 64
- 239000012466 permeate Substances 0.000 description 29
- 239000011550 stock solution Substances 0.000 description 25
- 208000005156 Dehydration Diseases 0.000 description 22
- 230000018044 dehydration Effects 0.000 description 22
- 238000006297 dehydration reaction Methods 0.000 description 22
- 238000004821 distillation Methods 0.000 description 21
- 238000000926 separation method Methods 0.000 description 21
- 239000000243 solution Substances 0.000 description 17
- 238000010612 desalination reaction Methods 0.000 description 16
- 238000010248 power generation Methods 0.000 description 16
- 230000004907 flux Effects 0.000 description 15
- 238000001223 reverse osmosis Methods 0.000 description 15
- 239000013535 sea water Substances 0.000 description 14
- 238000001816 cooling Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- 230000003247 decreasing effect Effects 0.000 description 6
- 230000001939 inductive effect Effects 0.000 description 6
- 239000004816 latex Substances 0.000 description 5
- 229920000126 latex Polymers 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000010842 industrial wastewater Substances 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 239000013522 chelant Substances 0.000 description 3
- 150000004697 chelate complex Chemical class 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 239000011777 magnesium Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 2
- 150000001342 alkaline earth metals Chemical class 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 229910052736 halogen Inorganic materials 0.000 description 2
- 150000002367 halogens Chemical class 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 229930006000 Sucrose Natural products 0.000 description 1
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910001420 alkaline earth metal ion Inorganic materials 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 235000011132 calcium sulphate Nutrition 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 235000013681 dietary sucrose Nutrition 0.000 description 1
- 239000010840 domestic wastewater Substances 0.000 description 1
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- GPRLSGONYQIRFK-UHFFFAOYSA-N hydron Chemical compound [H+] GPRLSGONYQIRFK-UHFFFAOYSA-N 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 238000004255 ion exchange chromatography Methods 0.000 description 1
- 238000004811 liquid chromatography Methods 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- 235000011147 magnesium chloride Nutrition 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
- 229960004793 sucrose Drugs 0.000 description 1
- 239000008400 supply water Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 239000012224 working solution Substances 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/002—Forward osmosis or direct osmosis
- B01D61/005—Osmotic agents; Draw solutions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/002—Forward osmosis or direct osmosis
- B01D61/0022—Apparatus therefor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
- F03G7/00—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for
Definitions
- Embodiments described herein relate to a water treatment system and a working medium.
- kitchen salt is generally used.
- Organic salts are also used as the solute of the draw solution.
- a draw solution of an organic salt has an inferior permeate flux of water to a draw solution of kitchen salt.
- a draw solution in which two or more kinds of solutes are mixed has been proposed.
- a synergistic effect is observed in a mixture of plural inorganic salts, but the flux passing through the osmosis membrane may decrease due to an adverse effect in the case of a mixture of an inorganic salt with saccharose.
- Embodiments provide a water treatment system capable of separating water at low cost and a working medium.
- a water treatment system of an embodiment includes: a first treatment container having an osmosis membrane to partition a first chamber for accommodating water to be treated and a second chamber for accommodating a working medium to induce osmotic pressure.
- the working medium is an aqueous solution containing a compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain, a compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain, or a compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain and a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain and an inorganic salt as a solute.
- Fig. 1 is a schematic diagram of a water treatment system according to an embodiment
- Fig. 2 is chemical formulas of a solute according to an embodiment
- Fig. 3 is a schematic diagram of a water treatment system according to an embodiment
- Fig. 4 is a schematic diagram of a water treatment system according to an embodiment
- Fig. 5 is a schematic diagram of a water treatment system according to an embodiment.
- a water treatment system according to a first embodiment will be described with reference to the schematic diagram illustrated in Fig. 1.
- a working medium B induces osmotic pressure in an osmotic pressure generator 1 including a first treatment container 11 equipped with an osmosis membrane 12 to partition a first chamber 13 for accommodating water to be treated A and a second chamber 14 for accommodating the working medium B.
- water C in the water to be treated A in the first chamber 13 permeates through the osmosis membrane 12 and moves to the working medium B in the second chamber 14 by the osmotic pressure difference generated between the water to be treated A in the first chamber 13 and the working medium B in the second chamber 14.
- the water treatment system of the embodiment is preferable from the viewpoint of being able to permeate the water C in the water to be treated A in the first chamber 13 through the osmosis membrane and to move the water C to the working medium B in the second chamber 14 at a high permeate flux by using the working medium B of the embodiment.
- the working medium B of the embodiment is used in a water treatment system which can be operated at low cost and a water treatment system.
- the first treatment container 11 is partitioned into the first chamber 13 and the second chamber 14 by the osmosis membrane 12.
- the first treatment container 11 is a resin or metal container which accommodates the water to be treated A in the first chamber 13 and the working medium B in the second chamber 14.
- the osmosis membrane 12 may be, for example, a forward osmosis membrane (FO membrane) or a reverse osmosis membrane (RO membrane).
- a preferred osmosis membrane is a FO membrane.
- osmosis membrane 12 for example, a cellulose acetate membrane, a polyamide membrane, or the like can be used.
- the osmosis membrane preferably has a thickness of 45 micrometre or more and 250 micrometre or less.
- the first chamber 13 is a region in the first treatment container 11 for accommodating the water to be treated A, and it is partitioned by the osmosis membrane 12.
- the first chamber 13 may be provided with an introduction and discharge path (not illustrated) through which the water to be treated A is introduced and discharged.
- the water to be treated A is a liquid having a lower solute concentration than the working medium.
- Examples of the water to be treated A may include a salt water (seawater and the like), lake water, river water, marsh water, domestic wastewater, industrial wastewater, or a mixture thereof.
- the salt (sodium chloride) concentration of the salt water may be, for example, from 0.05% to 8%.
- the water to be treated A contains salts such as sodium chloride, magnesium chloride, magnesium sulfate, calcium sulfate, and potassium chloride and suspended substances, and substances other than water are concentrated.
- the second chamber 14 is a region in the first treatment container 11 for accommodating the working medium B, and it is partitioned by the osmosis membrane 12.
- the second chamber 14 may be provided with an introduction and discharge path (not illustrated) through which the working medium B is introduced and discharged.
- the working medium B of the first embodiment is an aqueous solution containing a compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain, a compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain, or a compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain and a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain and an inorganic salt as a solute.
- the working medium B is an aqueous solution, and it thus contains water as a solvent.
- the working medium B containing such a solute is preferable since it exhibits a high osmotic pressure inducing action and suppresses the loss of solute of an inorganic salt. Hence, it is possible to generate a high permeate flux (Jw L/m 2 h) when water in the water to be treated A in the first chamber 13 permeates through the osmosis membrane 12 and moves to the working medium B in the second chamber 14.
- the water treatment system of the embodiment is also preferably utilized as a water treatment system which further includes a body of rotation and generates electricity by generating a water flow by induction of osmotic pressure and rotating the body of rotation by the water flow.
- solute reverse permeate flux Js mmol/m 2 h
- a compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain a compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain
- a compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain and a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain and an inorganic salt are contained as the compound of solute contained in the working medium B.
- the working solution of the embodiment maintains both a high solute concentration and a high osmotic pressure.
- the compound (molecule) having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain and the compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain are expressed by C x H y P z O w N s M t .
- M is a metal.
- the metal expressed by M is a metal of a metal salt of a carboxylic acid group or a metal of a metal salt of a phosphonic acid group.
- the metal of the metal salt is preferably an alkali metal.
- the metal of the metal salt is preferably Na, K, or Na and K.
- the elements or structures contained in the solute of the embodiment can be determined by analyzing the solute by liquid chromatography, separating the compounds having the respective peaks, and analyzing the compounds by using a NMR or organic element analyzer.
- the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain is preferably a compound in which a carboxylic acid group, a phosphonic acid group, or a carboxylic acid group and a phosphonic acid group of a compound having a structure expressed by Formula (1), (2), (3), (4), or (5) in Fig.
- Fig. 2 have a metal salt structure. Some or all of the carboxylic acid groups of the compound having a structure expressed by Formula (1), (2), (3), (4), or (5) in Fig. 2 are a metal salt of a carboxylic acid group. Some or all of the phosphonic acid groups of the compound having a structure expressed by Formula (1), (2), (3), (4), or (5) in Fig. 2 are a metal salt of a phosphonic acid group. Some of the side chains contained in the compound of the solute may contain a phosphonic acid group or a carboxylic acid group which is not a salt.
- R 11 to R 13 in Formula (1) are an alkyl chain of C n1 H 2n1 (n1 is any integer from 0 to 2).
- X 11 to X 13 in Formula (1) are each any one selected from the group consisting of -COOH, -P(OH) 2 , and OH. At least two X in one molecule are -COOH or -P(OH) 2 .
- nitrilotriacetic acid, N-(2-hydroxyethyl)iminodiacetic acid, and nitrilotris(methylenephosphonic acid) are preferable.
- Examples of the compound in which a carboxylic acid group, a phosphonic acid group, or a carboxylic acid group and a phosphonic acid group of the compound having a structure expressed by Formula (1) in Fig. 2 have a metal salt structure may include nitrilotriacetic acid 2Na salt, N-(2-hydroxyethyl)iminodiacetic acid 2Na salt, and nitrilotris(methylenephosphonic acid) 5Na salt.
- R 21 to R 27 in Formula (2) are an alkyl chain of C n2 H 2n2 (n2 is any integer from 0 to 2).
- X 21 to X 27 in Formula (2) are each any one selected from the group consisting of H, -COOH, -P(OH) 2 , and OH. At least two X in one molecule are -COOH or -P(OH) 2 . At least three X in one molecule are a functional group other than H.
- diethylenetriaminepentaacetic acid and diethylenetriaminepenta(methylenephosphonic acid) are preferable.
- Examples of the compound in which a carboxylic acid group, a phosphonic acid group, or a carboxylic acid group and a phosphonic acid group of the compound having a structure expressed by Formula (2) in Fig. 2 have a metal salt structure may include diethylenetriaminepentaacetic acid 3Na salt, diethylenetriaminepentaacetic acid 5Na salt, and diethylenetriaminepenta(methylenephosphonic acid) 7Na salt.
- R 31 to R 35 in Formula (3) are an alkyl chain of C n3 H 2n3 (n3 is any integer from 0 to 3).
- R 31 may have a hydroxyl group and may be bonded via one or more ether bonds.
- R 32 to R 35 may optionally contain a carboxylic acid group.
- X 31 to X 34 in Formula (3) are each any one selected from the group consisting of H, -COOH, -P(OH) 2 , and OH. At least two X in one molecule are -COOH or -P(OH) 2 . At least three X in one molecule are a functional group other than H. As the compound having a structure expressed by Formula (3) in Fig.
- metal salt structure may include N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid 3Na salt, 1,3-propanediaminetetraacetic acid 4Na salt, 1,3-diamino-2-propanol-N,N,N',N'-tetraacetic acid 2Na salt, glycol ether diaminetetraacetic acid 4Na salt, ethylenediaminedisuccinic acid 3Na salt, and ethylenediaminetetramethylenephosphonic acid 5Na salt.
- R 41 to R 49 in Formula (4) are an alkyl chain of C n4 H 2n4 (n4 is any integer from 0 to 2).
- X 41 to X 46 in Formula (4) are each any one selected from the group consisting of H, -COOH, -P(OH) 2 , and OH. At least two X in one molecule are -COOH or -P(OH) 2 . At least three X in one molecule are a functional group other than H.
- R 51 to R 54 in Formula (5) are an alkyl chain of C n5 H 2n5 (n5 is any integer from 0 to 2).
- X 51 to X 54 in Formula (5) are each any one selected from the group consisting of H, -COOH, -P(OH) 2 , and OH. At least two X in one molecule are -COOH or -P(OH) 2 . At least three X in one molecule are a functional group other than H.
- 3-carboxy-3-phosphonohexanedioic acid is preferable.
- Examples of the compound in which a carboxylic acid group, a phosphonic acid group, or a carboxylic acid group and a phosphonic acid group of the compound having a structure expressed by Formula (5) in Fig. 2 have a metal salt structure may include 3-carboxy-3-phosphonohexanedioic acid 5Na salt.
- the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain is preferably at least one kinds selected from the group consisting of nitrilotriacetic acid 2Na salt, N-(2-hydroxyethyl)iminodiacetic acid 2Na salt, diethylenetriaminepentaacetic acid 3Na salt, diethylenetriaminepentaacetic acid 5Na salt, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid 3Na salt, 1,3-propanediaminetetraacetic acid 4Na salt, 1,3-diamino-2-propanol-N,N,N',N'-tetraacetic acid 2Na salt, glycol ether diaminetetraacetic acid 4Na salt, ethylenediaminedisuccinic acid 3Na salt, and 3-carboxy-3-phosphonohexanedi
- the compound having plural metal salt structures of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain is preferably at least one kinds selected from the group consisting of nitrilotris(methylenephosphonic acid) 5Na salt, diethylenetriaminepenta(methylenephosphonic acid) 7Na salt, and ethylenediaminetetramethylenephosphonic acid 5Na salt.
- the compound having a metal salt structure of a carboxylic acid group and a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain is preferably at least one kinds selected from the group consisting of 3-carboxy-3-phosphonohexanedioic acid 5Na salt.
- the number of substitution of the metal salt changes depending on the pH.
- diethylenetriaminepentaacetic acid 3Na salt is weakly alkaline and diethylenetriaminepentaacetic acid 5Na salt is strongly alkaline.
- the pH of the working medium B in the embodiment is preferably 2 or more and 12 or less.
- the pH of the working medium B is measured by using the glass electrode type hydrogen ion densitometer manufactured by HORIBA, Ltd. and the method described in the manual.
- the total number of the carboxylic acid group and the phosphonic acid group contained in the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain, the compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain, or the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain and a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain is preferably 5 or more.
- the chelate is more stabilized and the effect of decreasing the loss of solute is more remarkable as the number of carboxylic acid groups and phosphonic acid groups contained is larger.
- the total number of the carboxylic acid group having a salt structure and the phosphonic acid group having a salt structure which are contained in the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain, the compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain, or the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain and a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain is preferably 5 or more.
- the chelate is more stabilized and the effect of decreasing the loss of solute is more remarkable as the total number of the carboxylic acid group and phosphonic acid group having a salt structure is larger.
- the concentration of the compound (solute) having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain, the compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain, or the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain and a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain in the working medium B is 0.05 mol/L or more and less than 1.0 mol/L and preferably 0.05 mol/L or more and 0.6 mol/L or less.
- concentration is too low since the osmotic pressure is weakly induced. In addition, it is not preferable that the concentration is too high since the loss of solute is great.
- concentration range is 0.2 mol/L or more and 0.6 mol/L or less.
- the inorganic salt (solute) in the working medium B is preferably a salt of an alkaline earth metal or an ammonium salt.
- the alkaline earth metal ion and the ammonium ion have an advantage of forming a stable chelate with the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain, the compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain, or the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain and a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain in the solution and thus decreasing the loss of solute.
- the inorganic salt (solute) is at least one kinds selected from the group consisting of a salt of carbonic acid, a salt of nitric acid, a salt of sulfonic acid, a slat of phosphoric acid, and a salt of a halogen element for the reason of low cost.
- a specific preferred alkaline earth metal is Mg, Ca, or Mg and Ca, and Mg is more preferable.
- a specific preferred halogen element is Cl.
- As the inorganic salt a salt of sulfonic acid or a salt of Cl is more preferable.
- the concentration of the inorganic salt (solute) in the working medium B is preferably 0.05 mol/L or more.
- concentration of the inorganic salt (solute) in the working medium B is preferably 0.4 mol/L or more and 10.0 mol/L or less and more preferably 0.4 mol/L or more and 5.0 mol/L or less.
- the concentration of the inorganic salt (solute) in the working medium B is preferably higher than the concentration of the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain, the compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain, or the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain and a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain from the viewpoint of forming a chelate complex.
- the second embodiment is common to the first embodiment except that an amino acid having a metal salt structure of a carboxylic acid group is used instead of the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain, the compound having a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain, or the compound having a metal salt structure of a carboxylic acid group in a main chain, a side chain, or a main chain and a side chain and a metal salt structure of a phosphonic acid group in a main chain, a side chain, or a main chain and a side chain of the first embodiment.
- an amino acid is a low molecule, thus the solute moves to the liquid to be treated A side and the loss of solute is likely to be caused, but a complex is formed as an inorganic salt is used concurrently. Accordingly, the embodiment has an advantage that an amino acid hardly permeates through the osmosis membrane 12 even when being used as the solute to induce osmotic pressure.
- a salt of an amino acid is inexpensive, and the water treatment system of the embodiment having minor loss of solute is thus effective for cutting down the running cost.
- Examples of the amino acid having a metal salt structure of a carboxylic acid group may include arginine.
- the concentration of the amino acid (solute) having a metal salt structure of a carboxylic acid group in the working medium B is less than 1.0 mol/L.
- the concentration of the amino acid (solute) having a metal salt structure of a carboxylic acid group in the working medium B is preferably 0.05 mol/L or more and 0.4 mol/L or less and more preferably 0.05 mol/L or more and 0.4 mol/L or less.
- the first chamber 13, the water to be treated A, the second chamber 14, the working medium B, and the osmosis membrane 12 are common to those in the first embodiment and the second embodiment.
- the water to be treated A is a salt water (aqueous solution of sodium chloride) such as seawater.
- the working medium B to be used in the second embodiment is the working medium B of the first embodiment or the second embodiment.
- the reference numerals of water to be treated, working medium, and water in the water treatment system are not illustrated, but the reference numerals thereof are common to those in the water treatment system in Fig. 1.
- a desalination system 200 is equipped with an osmotic pressure generator 1, a diluted working medium tank 2, a reverse osmosis membrane separator 3, and a concentrated working medium tank 4.
- the osmotic pressure generator 1, the diluted working medium tank 2, the reverse osmosis membrane separator 3, and the concentrated working medium tank 4 are connected in this order to form a loop.
- the working medium B (draw solution) which induces osmotic pressure circulates through this loop.
- the working medium B circulates through the osmotic pressure generator 1, the diluted working medium tank 2, the reverse osmosis membrane separator 3, and the concentrated working medium tank 4 in this order.
- the upper and the lower are the directions illustrated in the drawings, and for example, the concentrated working medium tank 4 is on the upper side of the diluted working medium tank 2, and the osmotic pressure generator 1 is on the left side of the reverse osmosis membrane separator 3.
- a tank of water to be treated 15 is connected to the upper part of a treatment container 10 in which the first chamber 13 is located through a pipeline 101a.
- a first pump 16 is provided to the pipeline 101a.
- a pipeline 101b for discharging the concentrated water to be treated A is connected to the lower part of the first treatment container 11 in which the first chamber 13 is located.
- the reverse osmosis membrane separator 3 is equipped with, for example, an airtight second treatment container 21.
- the second treatment container 21 is partitioned in, for example, the horizontal direction by a reverse osmosis membrane (RO membrane) 22, and a third chamber 23 is formed on the left side of the reverse osmosis membrane 22 and a fourth chamber 24 is formed on the right side thereof.
- RO membrane reverse osmosis membrane
- the diluted working medium tank 2 is connected to the lower part of the second treatment container 21 in which the third chamber 23 is located through a pipeline 101e.
- a third pump 25 is provided to the pipeline 101e.
- the upper part of the second treatment container 21 in which the third chamber 23 is located is connected to the concentrated working medium tank 4 through a pipeline 101f.
- the lower part of the second treatment container 21 in which the fourth chamber 24 is located is connected to a pure water tank 26 through a pipeline 101g.
- the pure water tank 26 the water (fresh water) which has moved to the fourth chamber through the reverse osmosis membrane 22 when concentrating the working medium B is accommodated.
- a pipeline 101h for delivering pure water in the pure water tank 26 to the outside and recovering the pure water is connected to the pure water tank 26.
- An on-off valve 27 is provided to the pipeline 101h. For example, the on-off valve 27 is opened when pure water in the pure water tank 26 exceeds a certain amount.
- the concentrated working medium tank 4 is connected to the upper part of the first treatment container 11 in which the second chamber 14 is located through a pipeline 101c.
- a second pump 17 is provided to the pipeline 101a.
- the lower part of the treatment container 10 in which the second chamber 14 is located is connected to the diluted working medium tank 2 through a pipeline 101d.
- the first pump 16 is driven to supply the water to be treated A (for example, seawater) from the tank of water to be treated 15 into the first chamber 13 of the osmotic pressure generator 1 through the pipeline 101a.
- the second pump 17 is driven to supply the concentrated working medium B from the concentrated working medium tank 4 into the second chamber 14 of the osmotic pressure generator 1 through the pipeline 101c.
- the solute concentration of the concentrated working medium B supplied to the second chamber 14 is higher than the salt concentration of the seawater supplied to the first chamber 13.
- an osmotic pressure difference is generated between the seawater in the first chamber 13 and the concentrated working medium B in the second chamber 14, and water in the seawater permeates through the osmosis membrane 12 and moves into the second chamber 14.
- the concentrated working medium B in the second chamber 14 is an aqueous solution containing the solute of the first embodiment or the second embodiment and exhibits a high osmotic pressure inducing action.
- a high permeate flux is generated when water in the seawater in the first chamber 13 permeates through the osmosis membrane 12 and moves to the concentrated working medium B in the second chamber 14.
- the seawater is discharged as condensed seawater from the first chamber 13 through the pipeline 101b and the concentrated working medium B is diluted with the water moved as the water in the seawater moves from the first chamber 13 to the concentrated working medium B in the second chamber 14.
- the diluted working medium B in the second chamber 14 is delivered to the diluted working medium tank 2 through the pipeline 101d and stored therein.
- the third pump 25 is driven to supply the diluted working medium B in the diluted working medium tank 2 to the third chamber 23 of the second treatment container 21 of the reverse osmosis membrane separator 3 through the pipeline 101e at a desired pressure.
- the water in the diluted working medium B supplied to the third chamber 23 at a desired pressure forcibly permeates through the reverse osmosis membrane (RO membrane) 22 and moves to the fourth chamber 24.
- the diluted working medium B in the third chamber 23 is concentrated as water moves to the fourth chamber 24.
- the concentrated working medium B is delivered from the third chamber 23 to the concentrated working medium tank 4.
- the concentrated working medium B in the concentrated working medium tank 4 is supplied into the second chamber 14 of the osmotic pressure generator 1 as the second pump 17 is driven, and it is utilized in the desalination treatment for extracting water (pure water) from a salt water as described above.
- the water (pure water) moved to the fourth chamber 24 is delivered to the pure water tank 26 through the pipeline 101g.
- the on-off valve 27 is opened and the water is delivered to the outside through the pipeline 101h and recovered.
- the first treatment container 11 of the osmotic pressure generator is partitioned in the horizontal direction by an osmosis membrane to form the first chamber 13 and the second chamber 14, but the first treatment container may be partitioned into upper and lower parts by an osmosis membrane to form the first chamber 13 and the second chamber 14.
- solute it is preferable to add the solute to the concentrated working medium tank 4 and the like when the solute concentration in the working medium B is decreased by the desalination treatment.
- the concentration of the diluted working medium B is not only performed by using a reverse osmosis membrane separator equipped with a reverse osmosis membrane (RO membrane) but also may be performed by using any device as long as it can remove water in the diluted working medium B.
- RO membrane reverse osmosis membrane
- the working medium B to be used in the fourth embodiment is the working medium B of the first embodiment or the second embodiment.
- a concentration system 300 is equipped with an osmotic pressure generator 31, a diluted working medium tank 32, a membrane distillation and separation device 33, and a concentrated working medium tank 34.
- the osmotic pressure generator 31, the diluted working medium tank 32, the membrane distillation and separation device 33, and the concentrated working medium tank 34 are connected in this order to form a loop.
- the working medium B (draw solution) circulates through this loop.
- the working medium B circulates through the osmotic pressure generator 31, the diluted working medium tank 32, the membrane distillation and separation device 33, and the concentrated working medium tank 34 in this order.
- the osmotic pressure generator 31 is equipped with, for example, an airtight first treatment container 41.
- the first treatment container 41 is partitioned in, for example, a horizontal direction by an osmosis membrane 42 (for example, a forward osmosis membrane: FO membrane), and a first chamber 43 is formed on the left side of the osmosis membrane 42 and a second chamber 44 is formed on the right side thereof.
- a tank of water to be treated 45 containing water to be treated A for example, a stock solution such as industrial wastewater, is connected to the upper part of the first treatment container 41 in which the first chamber 43 is located through a pipeline 201a.
- a first pump 46 is provided to the pipeline 201a.
- a pipeline 201b for discharging the concentrated stock solution in the first chamber 43 to the outside is connected to the lower part of the first treatment container 41 in which the first chamber 43 is located.
- the concentrated working medium tank 34 is connected to the upper part of the first treatment container 41 in which the second chamber 44 is located through a pipeline 201c.
- a second pump 47 is provided to the pipeline 201c.
- the diluted working medium tank 32 is connected to the lower part of the first treatment container 11 in which the second chamber 44 is located through a pipeline 201d.
- the membrane distillation and separation device 33 is equipped with, for example, an airtight second treatment container 51.
- the second treatment container 51 is partitioned in, for example, a horizontal direction by a dehydration membrane 52 formed of, for example, a porous latex membrane, and a third chamber 53 is formed on the left side of the dehydration membrane 52 and a fourth chamber 54 is formed on the right side thereof.
- the diluted working medium tank 32 is connected to the lower part of the second treatment container 51 in which the third chamber 53 is located through a pipeline 201e.
- a first on-off valve 61, a heat exchanger 62, and a third pump 63 are provided to the pipeline 201e along the flow direction of the working medium B in this order.
- the heat exchanger 62 intersects, for example, a pipeline 201f of exhaust heat gas, and the working medium B is heated by heat exchange between the working medium B flowing through the pipeline 201e and the exhaust heat gas.
- the upper part of the second treatment container 51 in which the third chamber 53 is located is connected to the upper part of a circulation tank 64 through a pipeline 201g.
- the circulation tank 64 is connected to the portion of the pipeline 201e located between the first on-off valve 61 and the heat exchanger 62 through a pipeline 201h.
- a second on-off valve 65 is provided to the pipeline 201h.
- a loop is formed by the third chamber 53 of the membrane distillation and separation device 33, the circulation tank 64, and the pipelines 201e, 201g, and 201h which connect these members to each other.
- a diluted working medium circulation system is formed that the diluted working medium B which has been subjected to the dehydration treatment in the third chamber 53 to be described later and stored in the circulation tank 64 is circulated through the pipeline 201h, the pipeline 201e, the third chamber 53, and the pipeline 201g by opening the second on-off valve 65 and driving the third pump 63.
- the diluted working medium circulation system is isolated from the diluted working medium tank 32 by closing the first on-off valve 61.
- the circulation tank 64 is connected to the concentrated working medium tank 34 through a pipeline 201i.
- a fourth pump 66 is provided to the pipeline 201i.
- a first pure water tank 71 is connected to the upper part of the second treatment container 51 in which the fourth chamber 54 is located through a pipeline 201j.
- the second pure water tank 72 is connected to the lower part of the second treatment container 51 in which the fourth chamber 54 is located through a pipeline 201k.
- a third on-off valve 73 is provided to the pipeline 201k and closed when pure water is not circulated to store the pure water in the fourth chamber 54.
- the second pure water tank 72 is connected to the first pure water tank 71 through a pipeline 201m.
- a fifth pump 74 is provided to the pipeline 201m.
- a loop is formed by the first pure water tank 71, the fourth chamber 54 of the membrane distillation and separation device 33, the second pure water tank 72, and the pipelines 201j, 201k, and 201m which connect these members to each other.
- a pure water circulation and cooling system is formed that the pure water in the second pure water tank 72 is circulated through the pipeline 201m, the first pure water tank 71, the pipeline 201j, the fourth chamber 54, and the pipeline 201k by opening the third on-off valve 73 and driving the fifth pump 74.
- the second pure water tank 72 is connected to a pipeline 201n for delivering pure water in the second pure water tank 72 to the outside and recovering the pure water.
- a fourth on-off valve 75 is provided to the pipeline 201n. The fourth on-off valve 75 is closed when pure water is circulated described above, and it is opened when the pure water in the second pure water tank 72 exceeds a certain amount.
- the first pump 46 is driven to supply the stock solution of the water to be treated A (for example, industrial wastewater) from the tank of water to be treated 45 into the first chamber 43 of the osmotic pressure generator 31 through the pipeline 201a.
- the second pump 47 is driven to supply the concentrated working medium B from the concentrated working medium tank 34 into the second chamber 44 of the osmotic pressure generator 31 through the pipeline 201c.
- the concentrated working medium B supplied to the second chamber 44 has a higher concentration than the stock solution supplied to the first chamber 43.
- an osmotic pressure difference is generated between the stock solution in the first chamber 43 and the concentrated working medium B in the second chamber 44, and water in the stock solution permeates through the osmosis membrane 42 and moves into the second chamber 44.
- the concentrated working medium B in the second chamber 44 is an aqueous solution containing the solute of the embodiment and exhibits a high osmotic pressure inducing action.
- a high permeate flux is generated when water in the stock solution in the first chamber 43 permeates through the osmosis membrane 42 and moves into the working medium B in the second chamber 44.
- the stock solution is discharged from the first chamber 43 through the pipeline 201b and recovered as a concentrated stock solution as the water in the stock solution moves from the first chamber 43 to the concentrated working medium B in the second chamber 44 in the osmotic pressure generator 31.
- the concentrated working medium B is diluted with the water moved.
- the diluted working medium B in the second chamber 44 is delivered to the diluted working medium tank 32 through the pipeline 201d and stored therein.
- the first on-off valve 61 provided to the pipeline 201e is opened, the second on-off valve 65 provided to the pipeline 201h is closed, and the third pump 63 is driven.
- the diluted working medium B in the diluted working medium tank 32 is supplied to the third chamber 53 of the second treatment container 51 of the membrane distillation and separation device 33 through the pipeline 201e.
- the diluted working medium B is supplied to the third chamber 53, the diluted working medium B flowing through the pipeline 201e is heated by heat exchange between the diluted working medium B and the exhaust heat gas flowing through the pipeline 201f in the heat exchanger 62 which intersects the pipeline 201f.
- the pure water in the second pure water tank 72 is circulated through the pipeline 201m, the first pure water tank 71, the pipeline 201j, the fourth chamber 54, and the pipeline 201k, and the dehydration membrane 52 formed of a porous latex membrane of the membrane distillation and separation device 33 is cooled with pure water on the fourth chamber 54 side.
- the dehydration membrane 52 on the fourth chamber 54 side is cooled by the pure water circulation and cooling system.
- the dehydration membrane 52 of the membrane distillation and separation device 33 By cooling the dehydration membrane 52 of the membrane distillation and separation device 33 with circulating pure water in the fourth chamber 54 while supplying the diluted working medium B thus heated to the third chamber 53 of the membrane distillation and separation device 33 through the pipeline 201e, the water in the diluted working medium B evaporates in the third chamber 53 and the vapor permeates through the dehydration membrane 52 formed of a porous latex membrane, moves to the fourth chamber 54, and is cooled and condensed with circulating pure water to be incorporated into the pure water.
- the diluted working medium B is subjected to the dehydration treatment in the third chamber 53.
- the diluted working medium B subjected to the dehydration treatment in the third chamber 53 is delivered to the circulation tank 64 through the pipeline 201g and stored therein.
- the diluted working medium B stored in the circulation tank 64 is concentrated to a certain concentration by the dehydration treatment.
- the working medium B has a low concentration by the concentration to such an extent, and the working medium B is not suitable for use as the concentrated working medium B described above.
- the second on-off valve 65 is opened and the diluted working medium B subjected to the dehydration treatment in the tank 64 is allowed to flow out to the pipeline 201h.
- the first on-off valve 61 is closed to isolate the diluted working medium circulation system including the circulation tank 64, the pipeline 201h, the pipeline 201e, the third chamber 53, and the pipeline 201g from the diluted working medium tank 32.
- the diluted working medium B is concentrated so as to be used as the concentrated working medium B by repeatedly performing the dehydration treatment including the evaporation of water in the diluted working medium B in the third chamber 53, the permeation of the vapor through the dehydration membrane 52, the movement of the vapor to the fourth chamber 54, and the cooling and condensation of the vapor with the circulating pure water on the fourth chamber 54 side plural times.
- the second on-off valve 65 is closed to store the concentrated working medium B in the circulation tank 64.
- the water (pure water) moved to the fourth chamber 54 is delivered to the second pure water tank 72 together with the circulating pure water through the pipeline 201k.
- the concentrated working medium B at a concentration capable of being used as the concentrated working medium B is stored in the circulation tank 64, driving of the fifth pump 74 is stopped, circulation of pure water to the fourth chamber 54 is stopped, and the third on-off valve 73 is then closed.
- the first on-off valve 61 is opened, and the pure water is delivered to the outside through the pipeline 201n and recovered.
- the fourth pump 66 is driven to deliver the concentrated working medium B in the circulation tank 64 to the concentrated working medium tank 34 through the pipeline 201i.
- the concentrated working medium B in the concentrated working medium tank 34 is supplied into the second chamber 44 of the osmotic pressure generator 31 by driving the second pump 47, and it is utilized in the concentration treatment of the stock solution as described above.
- the stock solution is supplied to the first chamber 43, the concentrated working medium B is supplied to the second chamber 44, the water in the stock solution is moved from the first chamber 43 to the concentrated working medium B in the second chamber 44 to concentrate the stock solution, and the stock solution is discharged from the first chamber 43 through the pipeline 201b and recovered.
- the concentrated working medium B is diluted with the water moved, and the diluted working medium B is delivered to the diluted working medium tank 32 and stored therein.
- the diluted working medium B stored in the diluted working medium tank 32 is subjected to the operation of concentration by the diluted working medium circulation system including the third chamber 53 of the membrane distillation and separation device 33 and the pure water circulation and cooling system including the fourth chamber 54 of the membrane distillation and separation device 33 and delivered to the concentrated working medium tank 34 and the water (pure water) moved to the fourth chamber 54 is delivered from the second pure water tank 72 and recovered.
- the diluted working medium circulation system including the third chamber 53 of the membrane distillation and separation device 33 and the pure water circulation and cooling system including the fourth chamber 54 of the membrane distillation and separation device 33 and delivered to the concentrated working medium tank 34 and the water (pure water) moved to the fourth chamber 54 is delivered from the second pure water tank 72 and recovered.
- the concentration system 300 which can be operated at low cost and can efficiently perform the concentration treatment of a stock solution (water to be treated A) such as industrial wastewater and the recovery of water.
- the first treatment container 41 of the osmotic pressure generator is partitioned in the horizontal direction by an osmosis membrane to form the first chamber 43 and the second chamber 44, but the first treatment container may be partitioned into upper and lower parts by an osmosis membrane to form the first chamber 43 and the second chamber 44.
- the concentrated water to be treated A (for example, stock solution) in the first chamber 43 of the osmotic pressure generator 31 is delivered to the outside through the pipeline 201b, but the pipeline 201b may be connected to the tank of water to be treated 45 to form a loop by the tank of water to be treated 45, the pipeline 201a, the first chamber 43 of the osmotic pressure generator 31, and the pipeline 201b in the case of obtaining a stock solution concentrated to a higher concentration.
- it is desirable to determine the concentration degree of the stock solution in consideration of the osmotic pressure difference generated between the concentrated stock solution and the concentrated working medium B in the osmotic pressure generator 31.
- the dehydration membrane 52 of the membrane distillation and separation device 33 is not limited to a porous latex membrane, and any membrane may be used as long as it has the function of permeating vapor.
- the concentration of the diluted working medium B is not only performed by the membrane distillation and separation device 33 equipped with the dehydration membrane 52 but also may be performed by using any device as long as it can remove water from the diluted working medium B.
- a circulating osmotic power generation system 400 which is one example of a water treatment system according to the fourth embodiment will be described with reference to the schematic diagram illustrated in Fig. 5.
- Fig. 5 the same members as those in Fig. 4 are denoted by the same reference numerals, and the description thereon is omitted.
- the working medium to be used in the fourth embodiment is the working medium B of the first embodiment or the second embodiment.
- the water treatment system according to the fifth embodiment is a circulating osmotic power generation system.
- the circulating osmotic power generation system 400 is equipped with an osmotic pressure generator 31 for generating a water flow and a body of rotation 82 for generating electricity by the water flow generated by the osmotic pressure generator 31.
- the circulating osmotic power generation system 400 is equipped with the first chamber 43 for accommodating water, the second chamber 44 for accommodating the working medium B (draw solution) which induces osmotic pressure, the osmosis membrane 42 for partitioning the first chamber and the second chamber, a pressure exchanger 81 connected to the second chamber 44, and the body of rotation 82 connected to the pressure exchanger 81.
- the water in the first chamber 43 permeates through the osmosis membrane 42 and moves to the working medium B in the second chamber 44.
- the body of rotation 82 is rotated by the water flow accompanying the movement of water to the working medium B to generate electricity.
- the working medium B is an aqueous solution containing the solute of the embodiment and exhibits a high osmotic pressure inducing action.
- the working medium B containing water thus moved forms a water flow having a high pressure, and it is thus possible to rotate the body of rotation 82 at a higher speed to generate electricity. Consequently, it is possible to provide a water treatment system which can be operated at low cost and can efficiently rotate the body of rotation 82 to generate electricity.
- a turbine or a water wheel can be used as the body of rotation 82.
- the pressure exchanger 81 and the body of rotation 82 are provided to the pipeline 201b connected to the lower part (the exit side of the working medium B) of the first treatment container 41 in which the second chamber 44 of the osmotic pressure generator 31 is located along the flow direction of the working medium B in this order.
- the portion of the pipeline 201c on the downstream side in the flowing direction of the working medium B of the second pump 47 is connected to the upper part of the first treatment container 41 in which the second chamber 44 is located via the pressure exchanger 81.
- the diluted working medium B having a flux generated when water has moved from the first chamber 43 to the second chamber 44 through the osmosis membrane 42 is allowed to flow out from the lower part of the first treatment container 41 in which the second chamber 44 is located through the pipeline 201b provided with the pressure exchanger 81.
- the pipeline 201c through which the concentrated working medium B flowed out from the concentrated working medium tank 34 flows passes through the pressure exchanger 81.
- the pressure of the diluted working medium B is lowered and the pressure of the concentrated working medium B is raised by pressure exchange between the concentrated working medium B and the diluted working medium B flowed out from the second chamber 44 in the pressure exchanger 81.
- water is accommodated in the tank of water to be treated 45.
- the first pump 46 is driven to supply water from the tank of water to be treated 45 into the first chamber 43 of the osmotic pressure generator 31 through the pipeline 201a.
- the second pump 47 is driven to supply the concentrated working medium B from the concentrated working medium tank 34 into the second chamber 44 of the osmotic pressure generator 31 through the pipeline 201c.
- the concentrated working medium B supplied to the second chamber 44 has a sufficiently higher concentration compared to the water only of the solvent supplied to the first chamber 43.
- the osmotic pressure difference is generated between the water in the first chamber 43 and the concentrated working medium B in the second chamber 44, and the water permeates through the osmosis membrane 42 and moves into the second chamber 44.
- the working medium B in the second chamber 44 is an aqueous solution containing the solute of the embodiment and exhibits a high osmotic pressure inducing action.
- a high permeate flux is generated when water in the first chamber 43 permeates through the osmosis membrane 42 and moves to the working medium B in the second chamber 44.
- the water in the first chamber 43 is discharged through the pipeline 201b.
- the diluted working medium B having a high pressure in the second chamber 44 is delivered to the diluted working medium tank 32 through the pipeline 201d and stored therein.
- the pressure exchanger 81 and the body of rotation 82 are provided to the pipeline 201d along the flow direction of the working medium B in this order.
- the pressure of the diluted working medium B is lowered and the pressure of the concentrated working medium B is raised by pressure exchange between the concentrated working medium B which flows from the concentrated working medium tank 34 through the pipeline 201c and the diluted working medium B which has a high pressure and flows from the second chamber 44 (through the body of rotation 82) through the pipeline 201d in the pressure exchanger 81 as described above.
- the diluted working medium B having an appropriate pressure by pressure exchange flows to the body of rotation 82 and efficiently rotates it to generate electricity.
- the concentrated working medium B having an appropriate pressure by pressure exchange is supplied to the second chamber 44.
- the diluted working medium B stored in the diluted working medium tank 32 is concentrated by the diluted working medium circulation system including the third chamber 53 of the membrane distillation and separation device 33 and the pure water circulation and cooling system including the fourth chamber 54 of the membrane distillation and separation device 33 in the same manner as the concentration system 300 illustrated in Fig. 4 described above.
- the diluted working medium B is stored in the circulation tank 64 as a working medium B (concentrated working medium B) at a concentration capable of being used as the concentrated working medium B by repeatedly performing the dehydration treatment including the evaporation of water in the diluted working medium B in the third chamber 53, the permeation of the vapor through the dehydration membrane 52, the movement of the vapor to the fourth chamber 54, and the cooling and condensation of the vapor with the circulating pure water on the fourth chamber 54 side plural times, and the concentrated working medium B is returned to the concentrated working medium tank 34.
- the concentrated working medium B in the concentrated working medium tank 34 is supplied into the second chamber 44 of the osmotic pressure generator 31 by driving the second pump 47 in order to rotate the body of rotation 82 and thus to generate electricity as described above.
- the first treatment container of the osmotic pressure generator is partitioned in the horizontal direction by an osmosis membrane to form the first chamber 43 and the second chamber 44, but the first treatment container may be partitioned into upper and lower parts by an osmosis membrane to form the first chamber 43 and the second chamber 44.
- the water in the first chamber 43 of the osmotic pressure generator 31 is delivered to the outside through the pipeline 201b, but the pipeline 201b may be connected to the tank of water to be treated 45 to form a loop by the tank of water to be treated 45, the pipeline 201a, the first chamber 43 of the osmotic pressure generator 31, and the pipeline 201b.
- the dehydration membrane 52 of the membrane distillation and separation device 33 is not limited to a porous latex membrane, and any membrane may be used as long as it has the function of permeating vapor.
- the concentration of the diluted working medium B is not only performed by using the membrane distillation and separation device 33 equipped with the dehydration membrane 52 but also may be performed by using any device as long as it can remove water from the diluted working medium B.
- a forward osmosis test was performed as follows.
- the CTA-ES membrane manufactured by HTI Corporation was set in a FO cell, pure water was placed on the active face side of the membrane as water to be treated, and the working medium was then placed on the support layer side. The time when the working medium was completely placed was counted as 0 minute, and this state was left to stand for 20 minutes. After the test, the weight of the liquid on the active face side was measured, and the permeate flux (Jw) was calculated from the difference before and after the test by taking the specific gravity of the liquid as 1.
- DTPA diethylenetriaminepentaacetic acid 5Na salt
- DTPMP diethylenetriaminepenta(methylenephosphonic acid) 7Na salt
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- Water Supply & Treatment (AREA)
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- Separation Using Semi-Permeable Membranes (AREA)
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