WO2008134825A1 - Desalination method and apparatus - Google Patents
Desalination method and apparatus Download PDFInfo
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- WO2008134825A1 WO2008134825A1 PCT/AU2008/000642 AU2008000642W WO2008134825A1 WO 2008134825 A1 WO2008134825 A1 WO 2008134825A1 AU 2008000642 W AU2008000642 W AU 2008000642W WO 2008134825 A1 WO2008134825 A1 WO 2008134825A1
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- WIPO (PCT)
- Prior art keywords
- membrane
- water
- molecular sieve
- porous inorganic
- desalination apparatus
- Prior art date
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- 238000010612 desalination reaction Methods 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 34
- 239000012528 membrane Substances 0.000 claims abstract description 159
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 88
- 239000012466 permeate Substances 0.000 claims abstract description 58
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000002808 molecular sieve Substances 0.000 claims abstract description 39
- 239000012465 retentate Substances 0.000 claims abstract description 22
- 150000003839 salts Chemical class 0.000 claims description 32
- 239000011148 porous material Substances 0.000 claims description 25
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 16
- CPUDPFPXCZDNGI-UHFFFAOYSA-N triethoxy(methyl)silane Chemical compound CCO[Si](C)(OCC)OCC CPUDPFPXCZDNGI-UHFFFAOYSA-N 0.000 claims description 10
- 239000000377 silicon dioxide Substances 0.000 claims description 8
- 239000010457 zeolite Substances 0.000 claims description 6
- 238000011010 flushing procedure Methods 0.000 claims description 3
- 230000004907 flux Effects 0.000 abstract description 20
- 230000008569 process Effects 0.000 description 12
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 11
- 238000005373 pervaporation Methods 0.000 description 10
- 239000007788 liquid Substances 0.000 description 8
- -1 salt ions Chemical class 0.000 description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 7
- 239000003651 drinking water Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000002454 metastable transfer emission spectrometry Methods 0.000 description 7
- 238000001223 reverse osmosis Methods 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 238000001914 filtration Methods 0.000 description 6
- 230000002829 reductive effect Effects 0.000 description 6
- 239000013535 sea water Substances 0.000 description 6
- 239000011734 sodium Substances 0.000 description 6
- 229910052708 sodium Inorganic materials 0.000 description 6
- 239000011780 sodium chloride Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 235000012206 bottled water Nutrition 0.000 description 5
- 238000004821 distillation Methods 0.000 description 5
- 239000013505 freshwater Substances 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- 230000008929 regeneration Effects 0.000 description 5
- 238000011069 regeneration method Methods 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 238000013459 approach Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 229910021536 Zeolite Inorganic materials 0.000 description 3
- 230000033228 biological regulation Effects 0.000 description 3
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000004094 surface-active agent Substances 0.000 description 3
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000001354 calcination Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 235000020188 drinking water Nutrition 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229920002614 Polyether block amide Polymers 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 150000003842 bromide salts Chemical class 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 238000000909 electrodialysis Methods 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000009285 membrane fouling Methods 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 description 1
- 229960000909 sulfur hexafluoride Drugs 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 230000002277 temperature effect Effects 0.000 description 1
- NAWZSHBMUXXTGV-UHFFFAOYSA-M triethyl(hexyl)azanium;bromide Chemical compound [Br-].CCCCCC[N+](CC)(CC)CC NAWZSHBMUXXTGV-UHFFFAOYSA-M 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/02—Inorganic material
- B01D71/028—Molecular sieves
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/02—Inorganic material
- B01D71/028—Molecular sieves
- B01D71/0281—Zeolites
-
- 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
- B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
- B01D61/362—Pervaporation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D65/00—Accessories or auxiliary operations, in general, for separation processes or apparatus using semi-permeable membranes
- B01D65/02—Membrane cleaning or sterilisation ; Membrane regeneration
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2311/00—Details relating to membrane separation process operations and control
- B01D2311/14—Pressure control
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2321/00—Details relating to membrane cleaning, regeneration, sterilization or to the prevention of fouling
- B01D2321/32—By heating or pyrolysis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/448—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by pervaporation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/08—Seawater, e.g. for desalination
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/06—Pressure conditions
- C02F2301/063—Underpressure, vacuum
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/06—Pressure conditions
- C02F2301/066—Overpressure, high pressure
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
Definitions
- This invention relates to a method and apparatus for desalination of water which advantageously may have lower energy requirements than current desalination processes.
- it relates to a method and apparatus for use in converting brackish water or sea water to potable water.
- the scarcity of potable water can be addressed in a number of ways including water conservation (through storage and recycling) and reduced water usage. These approaches only preserve the available water, they do not increase the amount of freshwater available. The most promising approach for increasing the amount of available potable water is desalination of sea water.
- the available desalination technologies can be grouped under two main technologies: thermal processes and membrane processes.
- the main membrane processes are reverse osmosis and electrodialysis.
- a significant and growing proportion of desalination capacity comes from reverse osmosis.
- reverse osmosis has a high energy requirement (to generate the pressure differential required to drive the process) or, if lower pressures are used, the process can suffer from low flux (thus requiring large membrane surface areas and thus a large plant investment).
- Membrane fouling is also a common problem requiring frequent membrane replacement and/or one or more pre-treatment steps.
- Pervaporation can be considered as a combination of permeation and evaporation.
- a liquid feed flows over one side of a membrane.
- One component of the liquid feed permeates favourably through the membrane with the remainder of the feed passing as the retentate.
- a minor vacuum on the permeate side of the membrane may be used to vaporise the permeate that has passed through the membrane.
- the permeate vapour is subsequently condensed to recover the desired component.
- Pervaporation is considered more effective than distillation as the separation is not limited by free surface thermodynamics.
- a water purification apparatus based on pervaporation has been described in United States patent number 6887385.
- the patent is mainly directed to using pervaporation for agricultural purposes.
- the pervaporation relies upon a humidity difference between the retentate side and the permeate side of a membrane.
- the membranes used are highly selective but at the cost of a very low flux of permeate.
- the feed is typically supplied in the form of vapour on the retentate side of the membrane in order to pass through the highly selective membrane.
- a desalination process based upon pervaporation is described by Zwinjnenberg et. al. [H.J. Zwijnenberg, G. H. Koops, M. Wessling; J. Membrance Sci. 250 (2005) 235-246] that utilises solar energy to heat the feed liquid.
- the key feature of this process is the use of dense polymeric membranes similar to those commonly employed in reverse osmosis and so the resulting flux was low.
- the process specifically uses polyetheramide-based polymer films and is more akin to a solar distillation process than pervaporation.
- Another process, referred to as vacuum membrane distillation is described by Meindersma et. al. [G. W. Meindersma, CM. Guijt, A.B. de
- the process has mainly been used for separating volatile components (such as chloroform) from aqueous solutions.
- the invention resides in a desalination apparatus comprising: a porous inorganic molecular sieve membrane comprising a retentate side and a permeate side; and a salty water inlet to direct salty water to the retentate side of the membrane, wherein water passing through the membrane, from the retentate side to the permeate side, is removed as a vapour from the permeate side of the membrane to maintain the permeate side of the membrane at a low water vapour pressure.
- the porous inorganic molecular sieve membrane comprises pores having a diameter of from 0.2 nm to 1.0 nm.
- the pores have a diameter of about 0.30 nm.
- the porous inorganic molecular sieve membrane is selected from the group consisting of methyl triethoxy silane molecular sieve membranes, carbonised template molecular sieve silica membranes and zeolites.
- the porous inorganic molecular sieve membrane is a carbonised template molecular sieve silica membrane.
- the salty water is supplied at a pressure above atmospheric pressure.
- the desalination apparatus may further comprise a water flush on the permeate side of the porous inorganic molecular sieve membrane.
- the invention resides in a method of desalinating water including the steps of:
- the water vapour can be removed from the permeate side of the porous inorganic molecular sieve membrane by the application of a vacuum. If required, the water vapour may be removed from the permeate side of the porous inorganic molecular sieve membrane by a flow of gas.
- the salty water is supplied at a pressure above atmospheric pressure.
- the salty water is supplied at a pressure of about 0.4 MPa.
- the method may further include the step of flushing salt from the permeate side of the porous inorganic molecular sieve membrane using water.
- FIG 1 is a schematic of a water desalination plant
- FIG 2 is a graph of desalination efficiency
- FIG 3 is a graph showing the flux over time for various salt concentrations for the CTMSS membrane
- FIG 4 is a graph showing the behaviour of flux and salt rejection with temperature for the CTMSS membrane.
- FIG 5 is a graph showing the behaviour of flux and salt rejection at various applied feed pressures for the CTMSS membrane.
- the membranes employed in the present invention are porous inorganic molecular sieve membranes formed on a supporting ⁇ -alumina substrate such as the type described in our granted United States patent number 6943123 which may be formed via a two-step catalysed hydrolysis sol-gel process.
- the method of synthesis of these membranes is detailed therein and its disclosure is hereby incorporated by reference.
- inorganic molecular sieve membrane is a term of the art used to refer to membranes which contain an inorganic element component. Thus, the membranes need not, and indeed are often not, entirely composed of inorganic elements. Organic, i.e. carbon-containing, chains and the like are often present and may be essential to generate the molecular sieve structure.
- the porous inorganic molecular sieve membranes referred to herein include those which are made up entirely of inorganic elements, such as certain zeolites, as well as those that comprise a mix of inorganic and organic components. They may be made up of substantially inorganic elements with a lesser amount of organic elements or may be substantially organic with a lesser amount of inorganic elements or contain comparable amounts of inorganic and organic elements.
- MTES methyl tri-ethoxy silane sol coated membrane
- CTMSS carbonised template molecular sieve silica membrane
- the films were deposited by the dip-coat method using an automatic dip coater in a dust-free laminar fume cupboard. Calcination of the films was conducted at 1°C per minute to 600 0 C for alumina and 500 0 C for methyl templated. Molecular sieve silica layers were ramped at 0.5 0 C to 500°C. All layers were repeated to reduce the likelihood of defects which might effect filtration performance.
- the CTMSS membrane is synthesised in a similar manner but with the addition of a short chain surfactant (one non-limiting example of such a surfactant is the inclusion of 3 wt% triethyl hexyl ammonium bromide) to the silica sol after the final acid/water addition.
- a short chain surfactant one non-limiting example of such a surfactant is the inclusion of 3 wt% triethyl hexyl ammonium bromide
- the surfactant is then carbonised in situ by calcination of the membrane under vacuum.
- FIG 1 there is shown a schematic layout of a desalination plant 1 based on a pervaporation membrane cell 2.
- the membrane 3 is a porous inorganic molecular sieve membrane formed on an ⁇ -alumina substrate.
- a feed liquid 4 is held in a reservoir 5 and supplied to one side of the membrane 3 under a mild positive pressure.
- the pressure is provided by a 20MPa source of nitrogen 6 and regulated by a pressure control valve 7. As discussed below, the pressure regulation is optional and is displayed for the purpose of depicting one possible embodiment only.
- the feed liquid 4 is suitably sea water or other brackish water. For the purposes of demonstration a number of saline solutions were produced with salt content ranging between 3 ppt (ppt stands for parts per thousand and is equivalent to 0.1 wt%) and 35 ppt (seawater-like concentration).
- the feed liquid 4 flows across the retentate side 8 of the membrane 3 and, eventually, to a retentate reservoir 9. Retentate flow is regulated by retentate flow valve 10.
- a mild vacuum is maintained on the permeate side 11 of the membrane 3 by vacuum pump 12.
- Permeate 13 water leaves the permeate side 11 of the membrane 3 as vapour which is captured in one or more vapour traps 14. Remaining water vapour exits as permeate 13, but most of this water is condensed and caught in vapour trap 14.
- the system may be operated by passing an at least partially dehumidified gas, such as dehumidified air or nitrogen, across the permeate side of the membrane, instead of a vacuum.
- an at least partially dehumidified gas such as dehumidified air or nitrogen
- the gas flow removes the water vapour which emerges on the permeate side of the membrane and the reduced partial pressure of water in the air will draw further permeate through the membrane.
- any method of removing water vapour from the permeate side of the membrane may be suitable.
- the vapour could be condensed using a simple condenser or the like instead of a trap, using a liquid pump at the bottom. The vacuum pump will not be required in these embodiments.
- the membranes of the invention are not perfectly selective so some small proportion of salt ions may pass through the membrane 3. Salt ions are not volatile so the salt is left behind on the permeate side 11 of the membrane 3 as the permeate water vapour is removed. If left unchecked the build up of salts could eventually block the pores and the flux through the membrane cell 2 would reduce.
- cyclic flush 15 (controlled by valve 17) is provided to the membrane cell 2. The permeate side 11 of the membrane 3 is washed with de-ionised water to remove salt build up.
- the frequency of the cyclic flush will depend upon the particular membrane used and conditions such as the concentration of the salt solution but may be activated anywhere from every 30 minutes up to once every few days, depending on the performance of the membrane i.e. higher salt rejection membranes would lead to a lower flushing frequency. A typical flush frequency would be once a day.
- the flush may be allowed to mix with permeate caught in the trap 14 for simplicity of operation. This is a reasonable approach as it may be desirable to have some small amount of sodium and chloride ions in the permeate. However, if this flush was removed separately at the end of the flush cycle, no salt would be caught in the vapour trap 14 and even purer water would be recovered. This gives greater flexibility and reliability when operating the membranes to achieve the best performance. Reverse osmosis does not allow this option.
- the membrane cell 2 is also provided with thermal regulation 16 which was used to demonstrate temperature effects in the desalination plant 1. Temperature regulation 16 is not an essential part of the invention. The effectiveness of the desalination plant 1 is demonstrated in FIG.
- MTES & CTMSS two different membranes
- the data points represent the salt rejection from liquid feed with salt concentrations of 3ppt, 11 ppt, 19ppt, 27ppt and 35ppt.
- the larger pore (0.5 nm) MTES membrane's ability to reject NaCI decreased from 93% at 3ppt to 83% at seawater-like concentrations, which still represents effective salt removal.
- the CTMSS membrane shows approximately 99.9% salt rejection at 3ppt but, as is evident in FIG 2, still reduced the salt content to near potable standard for even seawater-like concentrations of 35ppt (when the flush is mixed with the permeated vapour).
- High temperature regeneration is a feature of inorganic membranes which can be utilised in desalination to remove fouling species from the membrane.
- high temperature regeneration of the membrane 3 was performed at 500 0 C. Further testing of the membrane after high temperature regeneration demonstrated improved efficiency and potable water was obtained in one pass through the membrane of even the seawater solution. Desalination performance was, therefore, not reduced by the regeneration step, and in fact, improved performance was observed. High temperature regeneration can be performed between 200°C and 500 0 C. The membranes of the invention can be exposed to this heating step before use and so a membrane is obtained which can desalinate water to potable standards in one pass.
- This ability to withstand high temperatures is a useful feature of inorganic membranes and may, as mentioned above, be used to remove fouling from the membrane to regenerate efficiency of operation. This useful operation is not possible for filtration operations using organic polymeric membranes which cannot withstand such temperatures.
- FIG 3 demonstrates that total flux is close to 2 kg.m "2 .hr ⁇ 1 for at least up to 300 minutes for the CTMSS membrane. This flux is higher than for other molecular sieve membrane desalination technologies operating at the same or similar conditions.
- the flux is relatively consistent for all salt concentrations.
- Most prior art membrane distillation systems demonstrate temperature dependence and generally operate at elevated temperatures. As seen in FIG 4, which represents the changing flux and ion rejection with changing temperature for the CTMSS membrane at 7 bar feed pressure for the 35 ppt sodium chloride solution, the flux increases only marginally with temperature over a range from ambient to 60 degrees.
- the salt rejection is reduced, for the embodiment shown, at temperatures around and above 60°C.
- FIG 4 shows that this embodiment is particularly suitable for ambient temperature operation, thus reducing energy requirements and making the process more economic than known desalination techniques.
- this drop off in salt rejection is not necessarily demonstrated for all porous inorganic molecular sieve membranes and the inventor has found that certain zeolite membranes demonstrate excellent results at 80 0 C and the permeate can then be condensed at ambient temperatures. A range of operating temperatures is therefore envisaged depending on the nature of the particular membrane used.
- FIG 5 portrays the effect of pressure change on the retentate side (feed inlet) of the membrane on flux and salt rejection for the CTMSS membrane at 25°C for the 35 ppt solution.
- the major driving force for desalination using the present invention is the removal of the water vapour permeate as it emerges from the permeate side of the membrane. This results in the permeate side of the membrane being maintained at a low water vapour pressure. This means that the water, which emerges from the permeate side of the membrane as a vapour, is constantly removed and so the relative humidity of this side of the membrane is not allowed to build up to the point where there is no gradient for the water to continue to pass through the membrane.
- the present invention is suitable for desalination of water with a range of salt concentrations ranging from brackish to seawater.
- Water containing even higher amounts of salt, such as brine, may also be effectively desalinated although it will be appreciated that the flux and/or frequency of flush cycles may differ.
- the invention has been described in terms of desalination which is understood to be the removal of sodium and chloride ions from water, the same membranes and apparatus could be applied to the removal of ions of other salts from water.
- the size of the hyd rated ions resulting from the salt should be larger than the pores of the inorganic membrane which should be similar to or larger than the size of a water molecule. In this manner the salt ions will be substantially retained and the water allowed to pass through the membrane and emerge as a vapour at the permeate side for collection. Water molecules are approximately 0.26 nm in size while a hydrated sodium ion is 0.72 nm and a hydrated chloride is 0.66 nm.
- the membranes described herein effectively filter out the salt ions from the water molecules due to their greater size.
- the pores of the MTES membrane are 0.5 nm in diameter while those of the CTMSS are 0.3 nm. As both are smaller than the size of the hydrated sodium and chloride ions, truly molecular selective separation occurs.
- the MTES and CTMSS membranes are able to filter out the salt ions while allowing the smaller water molecules to pass.
- the pH of the salty solutions used in the apparatus of FIG 1 was kept around pH 7 and so any varying charge repulsion effects were minimised.
- the membrane pores cannot be entirely uniform in size.
- the CTMSS membrane is seen in FIG 2 to more effectively remove sodium chloride than the MTES membrane due to its smaller pore size.
- the pore size of the MTES membrane is considerably smaller than both the sodium and chloride ions there will naturally be a spread of pore sizes around the 0.5 nm average, the larger of which will allow some of these ions to pass.
- the CTMSS is the more effective membrane sieve as its average pore size is much closer to that of water and so even its larger pore sizes will generally be smaller than the hydrated sodium and chloride ions.
- the CTMSS membrane also provides advantages in stable performance which can be attributed to the carbonised templates which inhibit silica microstructure degradation.
- the pore diameters of the membranes of the present invention may, therefore, be between 0.1 to 1.0 nm.
- the pore diameters will be between 0.25 nm to 0.6 nm.
- the pore diameters will be about 0.30 nm.
- about 0.30 nm it is meant that the pore diameters may be 0.28 nm, 0.29 nm, 0.30 nm, 0.31 nm or 0.32 nm.
- the membranes and apparatus of the present invention may be suitable for the removal of other salts from water or another solvent so long as the diameter of the pores of the membrane are relatively similar to or slightly greater than the size of the solvent molecules to be allowed to pass through and collected as the permeate and smaller than the size of the hydrated ions which are to be substantially retained.
- other salts which may be removed using the method of the present invention include various of chlorides, bromides, sulphates and nitrates of magnesium, potassium, calcium and the like.
- any particular membrane for desalination or removal of various salts can be determined by reference to the membranes ability to selectively separate certain gases. This property is discussed in our granted US patent number 6943123. For example, the ability of a membrane to separate helium and sulphur hexafluoride or to separate hydrogen (0.29 nm in size) from nitrogen (0.36 nm) or carbon monoxide (0.38 nm) gives a good indication of the average pore size of the membrane and hence which salt ions it is capable of filtering out.
- Membranes of the zeolite family may have their pore size determined by other means such as X-ray diffraction.
- salt water should be understood to include any concentration of sodium chloride in water as well as aqueous solutions containing other dissolved salts in addition to or instead of, sodium chloride.
- the desalination results exhibited in FIG's 2-5 show that the present invention is capable of achieving desalination efficiency sufficient to generate potable water from sea water.
- the invention operates with a flux that is greater than known desalination processes including zeolite reverse osmosis and other membrane pervaporation technologies.
- the process is capable of operating efficiently at ambient temperature (around 25 0 C) 1 if desired, and with a low or ambient pressure feed.
Abstract
Description
Claims
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/599,121 US20110309016A1 (en) | 2005-08-24 | 2008-05-08 | Desalination method and apparatus |
AU2008247333A AU2008247333B2 (en) | 2007-05-08 | 2008-05-08 | Desalination method and apparatus |
EP08733460A EP2144853B1 (en) | 2007-05-08 | 2008-05-08 | Desalination method |
CN2008800166527A CN101730663B (en) | 2007-05-08 | 2008-05-08 | Desalination method and apparatus |
CA002687105A CA2687105A1 (en) | 2007-05-08 | 2008-05-08 | Desalination method and apparatus |
ZA2009/07941A ZA200907941B (en) | 2007-05-08 | 2009-11-11 | Desalination method and apparatus |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2007902436A AU2007902436A0 (en) | 2007-05-08 | Desalination | |
AU2007902436 | 2007-05-08 | ||
AU2007903758A AU2007903758A0 (en) | 2007-07-11 | Desalination method and apparatus | |
AU2007903758 | 2007-07-11 |
Publications (1)
Publication Number | Publication Date |
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WO2008134825A1 true WO2008134825A1 (en) | 2008-11-13 |
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PCT/AU2008/000642 WO2008134825A1 (en) | 2005-08-24 | 2008-05-08 | Desalination method and apparatus |
Country Status (6)
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EP (1) | EP2144853B1 (en) |
CN (1) | CN101730663B (en) |
AU (1) | AU2008247333B2 (en) |
CA (1) | CA2687105A1 (en) |
WO (1) | WO2008134825A1 (en) |
ZA (1) | ZA200907941B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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WO2016201498A1 (en) * | 2015-06-15 | 2016-12-22 | Dmac Ip Pty Ltd | Water treatment system and method |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
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CN106830195B (en) * | 2017-02-23 | 2021-03-26 | 大连理工大学 | Method for pervaporation desalination by NaA zeolite membrane |
US10596521B2 (en) | 2018-03-27 | 2020-03-24 | King Fahd University Of Petroleum And Minerals | Water gap membrane distillation module with a circulating line |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3405058A (en) * | 1964-02-17 | 1968-10-08 | Wendell S. Miller | Purification of water |
US6943123B2 (en) | 2000-06-09 | 2005-09-13 | The University Of Queensland | Silica membranes and process of production thereof |
US20060144788A1 (en) * | 2004-12-03 | 2006-07-06 | Cath Tzahi Y | Vacuum enhanced direct contact membrane distillation |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3340186A (en) * | 1964-05-14 | 1967-09-05 | Research Corp | Recovery of demineralized water from saline waters |
US5013447A (en) * | 1989-07-19 | 1991-05-07 | Sepracor | Process of treating alcoholic beverages by vapor-arbitrated pervaporation |
GB9723253D0 (en) * | 1997-11-04 | 1998-01-07 | Bratton Graham J | Water treatment process |
JP3686262B2 (en) * | 1998-07-27 | 2005-08-24 | 三井造船株式会社 | Mixture separation membrane |
US6440309B1 (en) * | 2000-05-17 | 2002-08-27 | Yoram Cohen | Ceramic-supported polymer (CSP) pervaporation membrane |
US6340433B1 (en) * | 2000-09-15 | 2002-01-22 | Engelhard Corporation | Water purification using titanium silicate membranes |
FR2839656B1 (en) * | 2002-05-15 | 2005-03-25 | Cirad | PROCESS FOR EXTRACTING AT LEAST ONE COMPOUND CONTAINED IN A DIFFUSION FLUID THROUGH A POROUS MEMBRANE |
US8038887B2 (en) * | 2005-08-24 | 2011-10-18 | Lawrence Livermore National Security, Llc | Membranes for nanometer-scale mass fast transport |
-
2008
- 2008-05-08 CA CA002687105A patent/CA2687105A1/en not_active Abandoned
- 2008-05-08 AU AU2008247333A patent/AU2008247333B2/en not_active Ceased
- 2008-05-08 EP EP08733460A patent/EP2144853B1/en not_active Not-in-force
- 2008-05-08 CN CN2008800166527A patent/CN101730663B/en not_active Expired - Fee Related
- 2008-05-08 WO PCT/AU2008/000642 patent/WO2008134825A1/en active Application Filing
-
2009
- 2009-11-11 ZA ZA2009/07941A patent/ZA200907941B/en unknown
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3405058A (en) * | 1964-02-17 | 1968-10-08 | Wendell S. Miller | Purification of water |
US6943123B2 (en) | 2000-06-09 | 2005-09-13 | The University Of Queensland | Silica membranes and process of production thereof |
US20060144788A1 (en) * | 2004-12-03 | 2006-07-06 | Cath Tzahi Y | Vacuum enhanced direct contact membrane distillation |
Non-Patent Citations (1)
Title |
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See also references of EP2144853A4 |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016201498A1 (en) * | 2015-06-15 | 2016-12-22 | Dmac Ip Pty Ltd | Water treatment system and method |
AU2016278355B2 (en) * | 2015-06-15 | 2021-12-02 | Dmac Ip Pty Ltd | Water treatment system and method |
Also Published As
Publication number | Publication date |
---|---|
CA2687105A1 (en) | 2008-11-13 |
CN101730663B (en) | 2013-07-03 |
CN101730663A (en) | 2010-06-09 |
EP2144853A1 (en) | 2010-01-20 |
EP2144853A4 (en) | 2010-04-14 |
EP2144853B1 (en) | 2012-09-05 |
AU2008247333A1 (en) | 2008-11-13 |
AU2008247333B2 (en) | 2012-04-26 |
ZA200907941B (en) | 2010-11-24 |
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